What is a PCB antenna? How does it work?

5 11 月, 2024

PCB antennas are crucial in today’s compact wireless devices. These antennas are directly integrated into the PCB board, providing an efficient way to transmit and receive signals. They have become more and more important in IoT devices, smartphones, and many other electronic products.

What is a PCB Antenna?

A PCB antenna is an antenna built directly onto the printed circuit board, often as a conductive trace or embedded component. By integrating it directly onto the PCB, the antenna becomes a seamless part of the overall design, eliminating the need for separate antennas. The design principle of PCB antenna is based on electromagnetic field theory. By arranging a specific metal conductor pattern on the PCB board, an effective electromagnetic radiation and receiving structure can be formed, so as to achieve the transmission and reception of wireless signals.

This antenna uses PCB as the medium, through the PCB process to achieve, no need to assemble the antenna separately, testing and use are very convenient. PCB antenna can be directly integrated on the circuit board, easy to touch and damage, and easy to assemble.

PCB Antenna Types

PCB antennas come in different types, each suited to specific applications and requirements. The most common types include:

Monopole Antennas

These antennas are simple, consisting of a single conductor. They’re straightforward to design and offer decent performance for applications with limited space. Monopole antennas are ideal for Bluetooth and Wi-Fi applications, where simplicity is needed without compromising basic functionality.

Dipole Antennas

Known for their balanced design, dipole antennas use two conductors, often resulting in improved radiation patterns. They are commonly used in environments where the antenna needs to work effectively in multiple directions. Dipole antennas are popular in high-frequency applications.

Inverted-F Antennas (IFA)

This type features a ground plane and a radiating element shaped like an “F.” IFAs are compact and provide a stable, omnidirectional pattern, making them suitable for Wi-Fi and cellular applications. The structure of IFA antennas helps achieve good efficiency even in confined spaces.

Patch Antennas

These antennas are flat and rectangular, making them excellent for devices with strict space limitations. Often used in GPS and RFID applications, patch antennas offer directional radiation patterns, allowing them to focus energy toward specific areas, enhancing range and strength.

Slot Antennas

Slot antennas consist of a slot cut out of a conductive surface, with electromagnetic fields radiating from the slot. They are typically more directional, so they are suitable for specific point-to-point applications or where the signal needs to be targeted.

What is the Frequency Range of a PCB Antenna?

The frequency range of a PCB antenna depends on the design and intended application. Most PCB antennas operate within common wireless communication bands, such as 2.4 GHz for Wi-Fi, Bluetooth, and other short-range communications. However, they can be designed for various ranges, including sub-1 GHz bands (for long-range IoT applications) and frequencies as high as 5 GHz for Wi-Fi 6 and other high-speed networks.

Higher frequencies typically require smaller antennas, which aligns well with compact devices but may also affect range. Low-frequency antennas, on the other hand, are larger but provide greater coverage and are less affected by obstacles.

PCB antenna’s Basic Formulas

1. Wavelength Calculation

The wavelength (λ) of the signal is an essential parameter in designing antennas, especially for determining the length of a PCB trace antenna.

Where:

c = Speed of light (approximately 3×10^8m/s)

f = Frequency in Hz

For example, at 2.4 GHz (a common frequency for Wi-Fi and Bluetooth), the wavelength is around 12.5 cm.

2. Length of a Monopole Antenna

For a monopole antenna on a PCB, the length (L) of the antenna is typically set to one-quarter of the wavelength. This is known as a quarter-wave monopole antenna, which is commonly used in PCB designs.

This length provides a good balance of efficiency and compact size.

3. Length of a Dipole Antenna

A dipole antenna is usually designed to have a length of half the wavelength. The total length L for a dipole is:

Each “arm” of the dipole would then be a quarter-wavelength. This structure is well-suited for many applications due to its balanced design.

4. Inverted-F Antenna (IFA) Length Calculation

For an Inverted-F Antenna, the length of the main resonant arm is usually close to a quarter of the wavelength. This helps the IFA to maintain a compact form while still achieving effective performance:

Since IFAs often include a grounding element, they may be slightly shorter than traditional quarter-wave monopoles.

5. Impedance Matching

The impedance (Z) of the antenna needs to match the transmission line (typically 50 ohms) to maximize power transfer. For a basic dipole or monopole antenna, the impedance can be approximated with empirical formulas. For instance, a free-space dipole impedance is around 73 ohms, but this value changes on a PCB.

To achieve matching, adjustments can be made by changing the length or width of the antenna trace or by using matching networks with inductors or capacitors.

6. Resonant Frequency Calculation

The resonant frequency (f) of a PCB trace antenna depends on its physical length. Rearranging the wavelength formula allows you to solve for f if you know the length:

Where L would typically be one-quarter of the wavelength for a monopole or half for a dipole.

7. Effective Dielectric Constant Adjustments

PCB antennas are affected by the PCB material’s dielectric constant (ϵr). This changes the effective wavelength (λ):

Using this adjusted wavelength improves accuracy in trace length calculations for PCB antennas, especially when working with substrates with a high dielectric constant.

8. Bandwidth Calculation

The bandwidth of a PCB antenna can be approximated using the Quality Factor (Q) of the antenna:

Where Q is influenced by factors such as antenna length, material, and layout. Lower Q values usually provide broader bandwidth, which can be achieved through specific design choices like wider traces or shorter antennas.

9. Gain Estimation

The gain of a PCB antenna depends on its radiation pattern and efficiency. Although gain is typically measured rather than calculated, some estimates can be made based on the type of antenna and its efficiency. For simple PCB antennas, a rough gain value might range from 0 dBi (isotropic) for omnidirectional designs to 3–5 dBi for directional designs.

Are PCB Antennas Directional?

PCB antennas can be directional or omnidirectional, depending on their type and design. Directional antennas focus the energy in a specific direction, which increases range in that direction while reducing it in others. Omnidirectional antennas, in contrast, distribute the signal evenly in all directions, which is beneficial for applications where the device orientation may vary.

Patch antennas and slot antennas are generally more directional, suitable for point-to-point communication or when a targeted signal path is needed. Monopole and dipole antennas, however, are typically omnidirectional, making them ideal for devices like smartphones and IoT gadgets, where a consistent signal is required from various angles.

The choice between directional and omnidirectional antennas should align with the specific needs of the application. For example, in a warehouse, an omnidirectional antenna might be preferred for broad coverage, while a directional antenna could be beneficial for a remote control application.

What Are the Applications of PCB Antenna?

PCB antennas are used in a wide range of applications, including:

Consumer Electronics: PCB antennas are essential in smartphones, tablets, and laptops for Wi-Fi, Bluetooth, and cellular connectivity.
IoT Devices: Many IoT devices use PCB antennas for wireless data transmission, making them integral in smart homes, agriculture, and industrial monitoring.
Automotive: In vehicles, PCB antennas enable GPS, remote keyless entry, and other connectivity features, enhancing both functionality and user experience.
Medical Devices: PCB antennas are used in medical equipment for wireless communication, which enables real-time monitoring and diagnostics.
Wearables: PCB antennas are commonly found in wearable tech like fitness trackers and smartwatches, where compactness is a priority.
Industrial Equipment: Many industrial machines rely on PCB antennas for remote monitoring and control, helping to streamline operations and improve efficiency.

When choosing a PCB antenna, consider the application requirements, including size constraints, frequency range, and directional needs. PCB antennas bring numerous advantages to electronics, from consumer gadgets to industrial equipment. With the right antenna, you can achieve reliable wireless communication, keeping your designs efficient and effective in today’s connected world.

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What is Silkscreen on PCB?

4 11 月, 2024

If you’ve ever taken a close look at a printed circuit board (PCB), you might have noticed small text, symbols, and lines on the surface. These aren’t just for decoration — they make up the PCB’s silkscreen layer, which plays a key role in making the board readable and easy to assemble. Think of silkscreen as a guiding map that helps technicians identify components and connections quickly. From component labels to polarity indicators, this layer is a simple yet invaluable part of any well-designed PCB. Let’s dive into what silkscreening is, why it’s so useful, and what you need to know about its colors, materials, and application methods.

What is a Silkscreen on a PCB?

Silkscreen is a layer of ink applied to the PCB’s surface. Typically, you’ll find it on the top side, although it can also be placed on the bottom. Screen silkscreen is usually used to indicate useful information on the PCB board, which can help the user in the assembly process, and is used to mark the component value, part number, polarity and other information, but also contains the version, manufacturer and other information. You’ll often see labels, symbols, and small icons that guide people assembling or repairing the board. In a busy PCB layout, the silkscreen is a roadmap for where everything goes, helping avoid mix-ups and reducing assembly time.

What is the Purpose of Silkscreen?

The silkscreen layer’s primary purpose is to add clarity. By showing clear labels for components, it reduces the chance of error during assembly. When it’s time to troubleshoot, silkscreen also makes life easier by letting technicians locate parts quickly. Silkscreen may include warnings, brand logos, or model names, all helping to make the board more informative. Essentially, it saves time, improves accuracy, and simplifies the process from start to finish.

Silkscreen Information Include on PCB

Silkscreen can be letters, numbers, text. PCB screen printing is done during the PCB manufacturing process, but is used for the PCB assembly process step. Here are some common information that can be silkscreened.

1. Polarity reference sign

2. Determine the test point

3. Component bit number reference mark

4. Component boundary

5, component pin mark

6. Unique identification number for each board

7. Company logo

8. Version number

9. Date code

10, Manufacturer’s logo, serial number, lot number

11. Warning symbols

12. Regulatory marks

Regulatory marks are used to indicate that a design has passed inspection or complies with specific regulations. RoHS, FCC, CE and e-waste disposal marks are commonly found on consumer and commercial products that have passed relevant inspections.

If another mark is seen on a design that has been inspected for safety: the UL mark, this mark indicates that the design was manufactured and assembled by a UL-certified manufacturer according to the UL796 and UL94 standards.

What are the Colors of PCB Silkscreen?

The color of silkscreen is chosen based on readability. White is the most common choice, especially on boards with a green soldermask, because it has a very good readability. And it is a public color and is more friendly to manufacture.

In addition, other colors such as yellow, red, black are also commonly used in the initial stage of PCB board design, pink screen printing is a favorite color of some PCB Layout, but it is usually not recommended to use this color, because it has special characteristics and is not friendly to the manufacturing process.

PCB Silkscreen Symbol

Silkscreen symbols represent various components on the board, making it easier to find specific parts and identify their functions. For instance, “R” stands for resistors, “C” for capacitors, and “U” for integrated circuits. Symbols also show component orientation and polarity, which is crucial for accuracy in assembly. Well-organized symbols on the silkscreen save time and effort, especially during maintenance, as they allow technicians to pinpoint components instantly.

What is the Difference Between Silkscreen and Solder Mask?

Solder mask is a green or other color layer coated on the circuit board, which can play a role in protecting the board. Because there are usually many wires and components on the surface of the circuit board, it is easy to have problems such as short circuit or virtual welding during the welding process, which will lead to damage to the circuit board. Solder resistance layer can effectively avoid the occurrence of this problem. At the same time, the solder resistance layer can also improve the corrosion resistance and mechanical strength of the circuit board.

Solder mask and silkscreen are both coated on the circuit board, but their roles are different. The solder resistance layer is mainly used to protect the circuit board from welding problems, and the screen printing is used to identify the components and related information on the circuit board. In addition, the solder mask is usually green or other bright colors, and the screen printing is usually white or other light colors for easy identification.

What is the Screen Printing Method of PCB?

There are totally three ways to print silkscreen on a PCB surface, manual screen printing, LPI, and DLP. Let me introduce them for you:

1. Manual screen printing

Do this on the PCB when the registration tolerance is 0.005 inches or the line width is greater than 0.007 inches. Perform manual screen printing using a mold containing text and traces. Traces are made of nylon. The ink is directed to the layer or laminate by stenciling. Next, the ink is cured in a baking oven. This is one of the easy ways to create a silk-screen layer, and it also supports large fonts. Perfecting the art can take years.

2. Liquid Photo Imaging (LPI):

This method is used to screen print threads larger than 4 million. The process of LPI is almost the same as the application of solder mask. In this method, however, the laminate is coated with epoxy resin and then placed under ultraviolet light. The plate is cured and then developed. This method ensures greater accuracy than manual screen printing.

LPI uses white, which requires more ink than the other two types of screen printing. Such prints take a long time to set up.

3. Direct Legend Printing (DLP):

This is one of the other three processes that is expensive. In this process, an inkjet projector and acrylic ink will be used. The ink is applied to the PCB using CAD software. The ink is then exposed to ultraviolet light. Acrylic links are not suitable for PCBS that may have a silver surface.

How Thick is the Silkscreen on a PCB?

Silkscreen thickness is usually about 0.02 mm. This thin layer is enough to make the markings visible without interfering with the board’s layout or operation. The thinness is key because it keeps the board easy to handle without any obstruction or interference, but it’s thick enough that it won’t wear off easily during normal use.

Best Technology highly specialized not only in quick-turn PCB prototype and PCB assembly, but also medium and small volume PCB fabrication. We can provide silkscreen on your PCBs for you with various colors, and we will try our best to meet the demands of silkscreen. If you have any questions, please feel free to contact us, we will be happy to help you.

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What is an AOI in PCB?

1 11 月, 2024

AOI, or Automated Optical Inspection, is a process in PCB manufacturing that utilizes advanced imaging technology to inspect PCBs for potential defects. During the inspection, cameras capture detailed images of the PCB at different stages, comparing them against predefined standards to ensure every component is correctly placed and connected. AOI serves as a crucial step, helping detect manufacturing flaws that could lead to functional issues.

What is an AOI Machine in PCB?

AOI machine is a kind of inspection equipment based on optical principle, mainly used to detect various defects on a PCB board. The AOI device automatically scans the PCB through a high-definition CCD camera, acquires images, and compares the tested solder joints with qualified parameters in the database. After image processing, the defects on the PCB are checked, and the defects are displayed through the display or automatic signs for repair personnel to correct.

AOI detection is mainly composed of light source and its control subsystem, digital imaging and its control subsystem (including CCD/CMOS camera, image acquisition), image scanning motion mechanism and its control subsystem, image processing and optimization subsystem, image feature recognition and defect recognition subsystem, HMI and main control subsystem. These subsystems work together to scan the PCB and obtain the PCB image by controlling the light source, digital imaging, scanning and other subsystems, and then register the processed PCB image with the PCB standard image, extract features and compare and analyze the processed PCB image to determine whether the PCB has defects and the type of defects, and identify the location of defects.

What is the Basic Principle of AOI?

The principle behind AOI is quite straightforward: it illuminates the PCB through the light source, uses the optical lens to collect the reflected light of the PCB into the computer, and analyzes the color difference or gray ratio of the PCB information through the computer software, so as to judge the solder paste printing on the PCB, component placement, solder joint welding quality and so on. The AOI system can also analyze and count the defects to provide a basis for adjusting the process parameters of the manufacturing process.

In another word, it relies on optical imaging and pattern recognition to detect defects. AOI machines are programmed with reference images of a perfect PCB layout. They then scan each PCB, capturing images and comparing them pixel-by-pixel to the reference model. Variations between the scanned image and the reference indicate potential defects, prompting the machine to flag these areas for further review.

What are the Benefits of an AOI Machine?

1. Accuracy in Detection

AOI machines can identify defects that might be overlooked by manual inspection. The precision with which they analyze each PCB ensures high-quality output, reducing errors in the final product.

2. Speed and Efficiency

Automated inspection greatly speeds up the inspection process, especially valuable in large-scale manufacturing. With AOI, hundreds of PCBs can be checked in a fraction of the time required for manual inspection.

3. Cost Reduction

Early detection of defects prevents costly rework or scrap, saving both time and resources. By addressing issues during the early stages, AOI contributes to a smoother production process.

4. Consistency and Reliability

Unlike human inspection, which can vary, AOI provides consistent results every time. It applies the same criteria to every PCB, ensuring uniformity and quality across all batches.

5. Enhanced Quality Control

In a competitive market, high-quality products build trust with clients. AOI enables manufacturers to deliver high-standard PCBs, maintaining quality and reducing potential returns.

What Kinds of Defects Can Be Checked During AOI?

1. Soldering Issues

AOI machines are highly effective in identifying soldering defects, such as insufficient solder, excess solder, or bridging, which can interfere with connectivity.

2. Misalignment of Components

AOI can detect misaligned components or misplaced parts, which might cause issues in functionality or even physical interference on the PCB.

3. Component Presence and Orientation

The machine checks if all components are present and correctly oriented. Missing or rotated parts can lead to non-functioning circuits.

4. Short Circuits and Opens

AOI identifies unwanted connections (shorts) and incomplete circuits (opens), ensuring each connection is accurate and functional.

5. Surface Defects

Surface issues, including scratches, contamination, or other irregularities, are also detectable through AOI, contributing to the visual quality of the board.

6. Polarity and Value Verification

Some AOI systems can check component polarity and values, confirming that each component matches the required specifications for the PCB design.

AOI Applications

1. Consumer Electronics Manufacturing

Given the high volume of consumer electronics, AOI’s speed and accuracy are essential for maintaining efficiency without sacrificing quality. It is used for inspecting products like smartphones, laptops, and household appliances.

2. Automotive Industry

In automotive electronics, reliability is critical. AOI helps ensure that safety and performance-related components are defect-free, such as sensors, control units, and in-car entertainment systems.

3. Medical Devices

Medical equipment relies on precision and reliability. AOI in PCB inspection for medical devices ensures that these life-saving tools meet strict standards, minimizing risks in critical applications.

4. Aerospace and Defense

For aerospace and defense, where reliability and durability are paramount, AOI supports quality assurance in sensitive equipment, such as navigation systems and communication devices.

5. Telecommunications

In telecommunications, AOI assists in inspecting high-frequency PCBs, ensuring that communication devices remain operational and effective over long periods.

To ensure high quality of PCBA, Best Technology equipped with 3D online AOI to detect PCB defectives from all aspects. Contact us if you have any questions.

Tags: AOI, what is a aoi
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How to Reworking a PCB? PCB Rework and Repair Guide

31 10 月, 2024

PCB rework is a delicate yet vital process for restoring functionality to circuit boards with flaws or damages. It involves methodically removing, replacing, or modifying components to correct issues. Whether it’s due to design alterations, assembly errors, or minor repairs, PCB rework can save costs and prevent discarding entire units

What is the Process of PCB Rework?

The process of PCB rework generally follows a series of careful steps. Technicians start by inspecting the board to identify the defective areas. For rework, precise tools like soldering irons, hot air rework stations, or BGA rework machines are typically used.

Once heated, damaged or defective components are removed. A flux application ensures that the solder flows cleanly, which reduces the risk of bridging or insufficient connections. The next step is carefully placing a new component in place, using a microscope to ensure accuracy, particularly for small parts like surface-mount components. Finally, the connections are resoldered, and the board undergoes cleaning and testing.

What is the Difference Between Repair and Rework in PCB?

PCB repair and rework, though closely related, serve unique purposes within electronics manufacturing and servicing. Rework refers specifically to correcting issues in a PCB due to assembly errors or modifications required before the board is shipped to the customer. This process should be operated very carefully, including during removing, adjusting, or replacing components. For instance, rework might be needed if components were placed incorrectly, solder joints are weak, or the board has minor assembly defects.

Repair, however, addresses boards that have become faulty or non-functional after use. Repair focuses on bringing a board back to working condition, whether due to physical damage, such as broken traces or burnt components, or due to environmental factors like corrosion. While rework ensures the board meets its initial design intent, repair aims to recover a board’s functionality after it has failed. Both repair and rework require precise techniques and skilled technicians, but repair can be more complex due to the nature of post-production or operational damages.

In summary:

Rework: Fixing pre-delivery assembly issues to align the board with its intended design.
Repair: Restoring functionality to a damaged or non-functional board, often due to wear, damage, or environmental exposure.

How Many Times Can You Rework a PCB?

The number of rework attempts a PCB can safely endure depends on factors like the materials used in the board, the board’s structure (e.g., number of layers), and the rework methods applied. Typically, each rework cycle subjects the board to a heating process, which can wear down solder joints and laminate strength over time. For most PCBs, rework should be limited to two or three cycles to avoid degradation, as repeated heating can lead to pad lifting, warping, or delamination of the substrate, especially with multi-layer boards.

Multilayer PCBs with multiple embedded connections are particularly sensitive, as excessive heating can damage internal layers. High-temperature cycles weaken solder joints, increasing the risk of electrical faults. Some high-quality boards, particularly those designed for critical applications like aerospace or medical devices, may tolerate additional rework if built with durable materials, but general guidance suggests minimal rework attempts. Careful planning and accurate diagnostics are essential for minimizing rework cycles, ensuring the board’s lifespan is preserved.

Can a Damaged PCB Be Repaired?

Yes, in many cases, a damaged PCB can be repaired.

It depends on the type and extent of the damage. For example, broken traces, lifted pads, and minor component failures are often fixable. Using epoxy, technicians can repair lifted pads, while trace repair kits can restore broken connections. However, severe burns or extensive damage to multiple layers can make repairs impractical or costly. The best approach is to assess each situation individually and determine if repair is viable.

What Wire is Best for PCB Rework?

Using the right wire during PCB rework is crucial for achieving reliable connections. For rework, thin, lead-free solder wire with a flux core is often recommended. A wire diameter of 0.5mm to 0.8mm provides better control and precision, making it suitable for both small and large components. Lead-free solder is preferred in many industries due to environmental regulations, but it requires higher temperatures than traditional lead-based solders, so it’s essential to have proper temperature control.

Flux-core solder wire is essential as it allows for smoother, more reliable connections by promoting better solder flow and reducing oxidation at solder joints. Rosin-core flux is commonly used because it provides a strong bond and requires minimal cleaning. Additionally, if jumper wires are needed to bridge broken traces, insulated 30 AWG wire is ideal due to its fine gauge.

What is the IPC Standard for PCB Rework?

The IPC standards for PCB rework and repair are widely recognized and adhered to within the electronics industry to ensure quality and reliability. IPC-7711 and IPC-7721 specifically address rework, modification, and repair of printed circuit boards.

IPC-7711 provides guidelines for reworking and modifying electronic assemblies. This includes instructions on tools, temperature control, and safety practices necessary for removing and replacing components while preserving the board’s structure. It offers details on soldering and desoldering techniques that ensure high-quality connections after rework.
IPC-7721 focuses on the repair aspect, covering methods for handling damaged components and structural faults like broken traces, lifted pads, and substrate repair. This standard is critical for technicians performing repairs, as it outlines best practices for restoring physical and electrical integrity without compromising board function.

What is the Main Cause of PCB Failure?

PCB failures may cause from a variety of factors, with design flaws, manufacturing errors, and environmental stresses among the primary culprits. Here’s a closer look at some of the main causes:

Design Flaws: Poorly optimized PCB layouts can lead to issues like excessive heat buildup, inadequate trace width for current capacity, or improper component spacing.
Manufacturing Errors: Mistakes during the assembly process, such as improper soldering temperatures or placement inaccuracies, can lead to weak solder joints or misaligned components. These issues may not be apparent initially but can result in premature board failure.
Environmental Stress: PCBs exposed to extreme temperatures, humidity, or corrosive environments are at risk of damage. Moisture can cause short circuits or corrosion on solder joints and traces, while high temperatures may warp the board or degrade the substrate. Boards used in outdoor or industrial settings are especially vulnerable.
Electrostatic Discharge (ESD): Sensitive components can fail if exposed to static electricity.
Aging and Wear: Over time, boards and components naturally wear out. Solder joints may crack, components degrade, and thermal cycles lead to material fatigue.

If your PCB or PCBA can’t work, and don’t know where is the problem. You can contact Best Team to ask for help, we are professional in this industry.

Tags: pcb reworking, reworking a pcb
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What is Laser Direct Imaging in PCB Manufacturing?

30 10 月, 2024

‌What is Laser Direct Imaging?

Laser Direct Imaging (LDI) is a technology that uses a laser beam emitted by an ultraviolet laser to image directly on a PCB (printed circuit board). Compared to traditional exposure techniques, LDI has higher image quality, precision traces and real-time adjustment.

The LDI technology achieves pattern transfer by projecting the line image directly onto the PCB coated with photoresist through the laser beam emitted by the laser diode. This method eliminates the use of negatives in the traditional exposure process, reduces the time and cost of loading and unloading negatives, and avoids deviations caused by negative growing. The image resolution of LDI technology is high, and the fine wire can reach about 20um, which is suitable for the production of fine wire and improves the yield of PCB production.

What is Laser Direct Imaging in PCB Manufacturing?

Working Principle of LDI Technology

The principle of laser imaging is to acquire and present images based on the characteristics of laser beam. As we know, a laser is a highly focused, high-brightness, monochromatic beam that can therefore produce high-quality images. The laser imaging system mainly consists of laser, lens, scanning device and receiver. The laser is used to generate the laser beam, the lens is used to focus the beam, the scanning device is used to change the path of the beam on the object, and the receiver is used to receive the light signal and convert it into an image.

In the imaging process, the laser beam is focused from the laser through the lens, and then the path of the beam on the object is controlled by the scanning device. When the laser beam hits the surface of an object, it interacts with the surface. This interaction causes light to scatter and reflect, with scattered light diffusing in different directions and reflected light remaining in its original direction of propagation. The receiver receives the light scattered and reflected by the object and converts it into an electrical signal. The receiver converts the signal into a digital image signal, which is then processed and displayed on the screen to form an image. In the processing process, the received signal can be filtered, amplified and other operations to improve the quality and clarity of the image.

As PCB manufacturing processes continue to advance, LDI technology is also evolving. At present, the mainstream light source in the industry is the 405nm laser diode produced by Nichiya, Panasonic, and it is expected that the optical power requirements for exposure will be further improved in the future, and the optical power of a single device may develop to 100W. Nowadays, LDI technology is not only used in PCB manufacturing process, but also in high-end applications like medical imaging, industrial detection, remote sensing.

Advantages of Laser Direct Imaging Over Photo Exposure

The advantages of laser direct imaging (LDI) compared with traditional exposure machines mainly include the following aspects:

1. Eliminating the negative process in the exposure process

The LDI technology eliminates the step of making the negative in the traditional exposure process, thereby saving the time and cost of loading and unloading the negative, and reducing the deviation caused by the negative growth and contraction.

2. High resolution

The image resolution of LDI technology is very high, which is suitable for some very fine line production, especially for multi-layer PCB, which greatly improves the yield of PCB production.

3. High quality and precision

LDI is contactless operation, reducing the chance of miscontact, the closed operating environment reduces the influence of temperature and humidity, the image quality is high and fine, eliminating many defects in the traditional process.

4. Reduce errors and improve alignment

LDI technology improves alignment by eliminating alignment problems that often exist in photographic plates, especially the anisotropic movement of photographic plates caused by changes in temperature and humidity. High-precision alignment is achieved by using a charge-coupled device (CCD) camera system and a reference target to line up printed images and panels.

5. Shorten the production process and reduce costs

Because there is no need to have a negative production process, LDI technology shortens the production process, reduces the call of personnel, and reduces the production cost. In addition, the LDI system can lay more devices in the same environment, enabling two-way scanning and further savings.

6. Adapt to a variety of production needs

LDI technology has a flexible manufacturing route, which can meet various production needs without affecting the output. Once the data is delivered to the engineering department, production can begin, reducing product delivery time.

The image quality of LDI technology is clearer than that of traditional exposure technology, and it has obvious advantages in mid-to-high-end PCB manufacturing. With the transfer of global PCB production capacity to China and the high-end development of the electronics industry, the demand for LDI equipment continues to grow, and it is expected that the future will gradually replace traditional exposure equipment in the field of low-end PCB.

What is the Process of Direct Imaging?

Direct imaging with LDI involves several steps that ensure precise layer creation:

Design Preparation: The digital circuit design is prepped for imaging, with adjustments made to accommodate laser processing specifics.

Photoresist Coating: The PCB is coated with a light-sensitive photoresist material, which reacts chemically when exposed to the laser.

Laser Imaging: The laser projects the circuit pattern directly onto the photoresist. Adjustments can be made mid-process, allowing for precise alignment.

Developing: After exposure, the board is treated with a developer to reveal the circuit paths. Unexposed areas are removed, leaving only the intended design.

Etching or Plating: Depending on the PCB type, the board undergoes etching or plating to define the copper traces, completing the imaging process.

Difference Between Positive and Negative Images in PCB

In PCB photo exposure, the terms “positive” and “negative” refer to how the photoresist reacts to the laser exposure:

Positive Image: Here, the laser exposes areas intended to be removed. During development, the exposed regions dissolve, leaving behind the unexposed areas as the design.

Negative Image: In a negative image process, the laser exposes the regions meant to remain on the board. These exposed parts resist the developer, protecting the underlying material, while unexposed regions dissolve away.

The choice between positive and negative imaging depends on the photoresist type and the specific design requirements. Both methods offer high accuracy, but each has unique benefits based on the intended application.

Why LDI Process Less Cost-effective than Phototool?

While LDI offers many advantages, it often requires a higher initial investment than phototools:

1. Equipment Costs: LDI machines are sophisticated and costly, requiring a significant investment in laser technology and imaging systems.

2. Maintenance: High-precision lasers and optics demand regular maintenance and calibration to ensure consistent performance, which adds to operational costs.

3. Speed on Larger Runs: For high-volume production, phototools may still be more cost-effective. Phototools offer rapid replication without the need for repeated laser exposure, lowering costs for large-scale production.

These cost factors make LDI more suitable for specialized, lower-volume, or high-precision applications rather than large-batch productions.

How is Layer Registration in LDI?

Layer registration is crucial in PCB manufacturing, especially for multilayer boards where each layer must align precisely. LDI excels in this aspect:

1. Automated Alignment: LDI systems come with advanced alignment software that adjusts each laser exposure to match the existing layer positions.

2. Reduced Human Error: Since the process is largely automated, human handling is minimal, reducing the risk of alignment issues.

3. Dynamic Adjustment: With real-time feedback systems, LDI machines adjust alignment during the process, maintaining tight registration tolerances.

If you’re seeking high-quality PCB manufacturing, consider choosing a provider skilled in LDI processes like Best Technology. Our company combines expertise with cutting-edge technology to ensure your boards are produced to exact specifications, delivering the durability and performance you need in today’s advanced electronics.

Tags: laser direct imaging, LDI
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PCB Surface Treatments: A Comprehensive Guide

29 10 月, 2024

Printed Circuit Boards (PCBs) are the backbone of modern electronics. To ensure optimal performance and durability, PCBs undergo various surface treatments. These treatments protect the copper traces from corrosion, enhance solderability, and improve the overall reliability of the circuit board. In this article, we’ll explore the most common PCB surface treatments and their applications.

1. HASL (Hot Air Solder Leveling)

Principle

HASL is a traditional surface treatment that involves immersing the PCB in a bath of molten solder. After the solder solidifies, hot air is used to level the surface and remove excess solder.

Features

•Material: Lead-tin alloy (for traditional HASL) or lead-free solder (for LF HASL).

•Process: Immersion in molten solder followed by hot air leveling.

Advantages

•Excellent solderability.

•Cost-effective for large volumes.

•Good mechanical strength.

Picture

PCB Surface Treatments: A Comprehensive Guide

2. OSP (Organic Solderability Preservatives)

Principle

OSP involves applying a thin layer of organic material (usually a rosin-based compound) to the copper surface, which protects it from oxidation.

Features

•Material: Organic preservatives.

•Process: Application of organic film.

Advantages

•Environmentally friendly.

•Good solderability.

•Suitable for rework.

Picture

3. ENIG (Electroless Nickel Immersion Gold)

Principle

ENIG involves depositing a layer of nickel followed by a thin layer of gold on the copper surface. This provides a robust barrier against corrosion and ensures good solderability.

Features

•Material: Nickel and gold.

•Process: Electroless nickel deposition followed by immersion gold plating.

Advantages

•High reliability.

•Excellent solderability.

•Long shelf life.

Picture

4. ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold)

Principle

ENEPIG is similar to ENIG but adds a palladium layer between the nickel and gold. This improves the resistance to wear and tear.

Features

•Material: Nickel, palladium, and gold.

•Process: Electroless nickel deposition, electroless palladium, and immersion gold plating.

Advantages

•Superior wear resistance.

•Excellent solderability.

•Long-term reliability.

Applications

•High-reliability military and aerospace applications.

•High-frequency applications.

•Wire bonding

Picture

5. Gold Immersion (Direct Gold Plating)

Principle

Gold immersion directly deposits a layer of gold onto the copper surface without a nickel underlayer.

Features

•Material: Gold.

•Process: Direct gold plating.

Advantages

•High conductivity.

•Excellent solderability.

Silver Immersion

Principle

Silver immersion involves depositing a layer of silver onto the copper surface.

Features

•Material: Silver.

•Process: Immersion silver plating.

Advantages

•High conductivity.

•Low cost compared to gold.

Picture

6. Hard Gold (Selective Gold Plating)

Principle

Hard gold is a thicker and harder layer of gold, typically applied selectively to contact areas.

Features

•Material: Gold.

•Process: Selective gold plating.

Advantages

•High wear resistance.

•Good electrical contact properties.

Picture

7. Tin Immersion

Principle

Tin immersion deposits a layer of tin onto the copper surface.

Features

•Material: Tin.

•Process: Immersion tin plating.

Advantages

•Good solderability.

•Low cost.

Applications

•Cost-sensitive applications.

•General-purpose electronics.

Picture

Choosing the right surface treatment for your PCB depends on several factors, including the application environment, cost considerations, and performance requirements. Each treatment has its own set of advantages and limitations. Understanding these treatments will help you make informed decisions that enhance the performance and longevity of your electronic devices.

I hope this guide helps you understand the different surface treatments used in PCB manufacturing and their applications. If you have any questions or need further clarification, feel free to reach out!

Tags: pcb surface treatment, surface finishing
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What is ICT Full Form in PCB?

26 10 月, 2024

ICT Test Full Form

The full form of ICT is In-Circuit Testing. It is a method that always used to test assembled circuit board during manufacturing.

What is ICT in PCB?

In-circuit testing (ICT) is a method used to test assembled circuit boards during production. It ensures that every component on the PCB functions as expected. By applying electrical signals to the board, it checks for faults like open circuits, shorts, and wrong component values.

In PCB assembly, ICT is used for final testing after surface-mount components and through-hole components have been soldered onto the board. This test is highly effective in identifying assembly defects that might compromise the functionality of the final product.

ICT vs. FCT

Although ICT and FCT look similar, their purposes and focus are different.

In-Circuit Testing (ICT) is like a thorough quality check for individual components. It tests each resistor, capacitor, inductor, and IC on the board to make sure they’re installed and working as expected. ICT does this without focusing on the PCB’s complete function as a whole; instead, it looks for manufacturing faults or placement errors on each part of the circuit. This is perfect for catching problems before the PCB reaches final assembly.

Functional Circuit Testing (FCT), on the other hand, looks at the bigger picture. FCT checks if the assembled board works as intended in a simulated working environment. It mimics the real-world conditions the PCB will face once in use, testing the board as a whole rather than individual components. FCT aims to ensure that all parts are correctly interacting and that the board behaves as it should under operating conditions.

Together, ICT and FCT form a powerful duo: ICT focuses on each component’s accuracy, while FCT ensures that all the elements work smoothly as a cohesive unit. Using both tests provides a comprehensive check, enhancing the PCB’s overall quality and reliability before it reaches the end-user.

What Items Does ICT Test for on a PCBA?

When ICT tests a PCBA, it’s really looking for any faults or failures in the components and connections that could cause problems later on. Here’s what ICT commonly checks:

Resistors – It verifies that each resistor has the right resistance value and is correctly placed. If a resistor value is wrong, it can disrupt the whole circuit.
Capacitors – ICT checks capacitance levels and polarity (in specific cases) to make sure each capacitor is installed properly. Incorrect capacitors can lead to unstable performance.
Inductors – The test examines if inductors have the correct inductance values. Faulty inductors can cause power issues or signal problems.
Integrated Circuits (ICs) – ICT verifies that ICs are in the right orientation and connected properly to avoid shorts or opens, both of which can make the board malfunction.
Transistors – By checking transistor functionality, ICT ensures they won’t cause signal or power issues within the PCB.
Diodes – ICT makes sure diodes have correct polarity and work properly. Misplaced or faulty diodes can impact the flow of current, leading to circuit failure.
Solder Joints – ICT evaluates each solder joint, checking for breaks or poor connections. Bad solder joints lead to unstable electrical contact, which could cause intermittent issues or complete failure.

What is an ICT Machine?

An ICT machine is a specialized piece of equipment designed to perform in-circuit tests on PCBs. You can see it from below picture. The ICT machine uses a test fixture, also called a “bed of nails,” containing numerous tiny probes or pins. Each probe aligns with a specific point on the PCB, making contact with various circuit points to evaluate the electrical connections.

Once a PCB is placed in the test fixture, the machine applies signals through the probes to test individual components. It checks electrical properties such as resistance, capacitance, and voltage at each node. If a component is misplaced, missing, or faulty, the machine flags it immediately.

With its speed and precision, an ICT machine is an invaluable tool in high-volume production lines. While setting up an ICT machine requires creating a test fixture for each PCB, they save much time and human during the manufacturing process, make sure a fast delivery.

What Are the 7 Types of PCB Testing Methods?

In addition to ICT testing, there are other 6 types of PCB testing methods that widely used. Let’s talk about them one by one.

1. Flying Probe Testing

A testing method mainly used for prototypes or small/low volume orders. In Flying Probe Testing, multiple movable probes make contact with test points on the board. Unlike ICT, it doesn’t require a fixture, making it highly flexible and cost-effective for small production runs. However, compared with ICT testing, it’s relatively slower than ICT because it tests points sequentially.

2. Functional Circuit Testing (FCT)

FCT is a method that check whether PCBA works correctly. It is typically come after ICT, and in almost factory, it is the last process to confirm that every component works together correctly.

3. Burn-In Testing

Burn-in Testing (also called aging test) pushes the board to its limits by applying high temperatures, loads, or voltages for extended periods. It can spot failures in components that might not withstand the stress of real-world conditions. Burn-in testing is often used for products that need high reliability, such as aerospace and medical devices.

4. X-Ray Inspection

For multilayer or densely packed PCBs, X-ray inspection is must to do. It helps visualize hidden solder joints and component placements that inspectors can’t found by naked eyes. X-ray inspection is invaluable for boards with fine-pitch components such as BGAs, QFNs, or those where hidden joints can’t be inspected visually.

5. Automated Optical Inspection (AOI)

AOI uses cameras to visually inspect the board for common issues like misalignment, missing components, or faulty solder joints. This is a quick and effective way to catch visible defects. AOI is widely used in automated production lines, as it quickly flags any boards that require closer examination. To get highest quality and no-defect products, Best Technology equipped with online dual track AOI to inspect PCBA.

6. Boundary Scan Testing

Boundary Scan Testing is particularly useful for complex boards where physical probing is challenging. It involves using ICs that support scan testing, so that engineers to check connectivity between ICs and other critical points. Boundary scan is common in high-density boards like those found in telecommunications.

Each method brings a unique advantage to PCB testing. In-Circuit Testing (ICT) is highly effective for large-scale quality control, while Flying Probe Testing is better suited for prototypes and smaller batches. Together, these tests form a complete strategy for delivering reliable, high-quality PCBs across various production needs.

How does ICT Testing?

ICT works by using a bed-of-nails (BON) tester or test probes to connect to specific test points on a PCB. Electrical signals are then sent through the board, and the responses are analyzed. Here’s how it works in simple steps:

Connection: The PCB is placed on the ICT machine, where test pins contact the board at designated points.
Signal Application: The ICT machine applies electrical signals to test the components individually or in groups.
Data Collection: The responses from each component are recorded to determine if it matches the expected output.
Fault Identification: Any deviations from expected responses are flagged, identifying potential defects like soldering errors, component failures, or incorrect placements.

FAQs about ICT

Q: What is ICT?

A: ICT (In-Circuit Test System), commonly known as online tester In Chinese, is mainly used for the test of assembled Circuit boards (PCBA).

Q: Which components can ICT basic functions measure?

A: On, short circuit, resistance, capacitance, inductance, diode, IC protection diode test, etc.

Q: Why use ICT?

A: According to the statistical data of the circuit board assembly industry, assembly defects are mainly reflected in the welding open circuit, short circuit, offset, missing parts and other aspects, accounting for more than 90%, so the principle of online testing technology application is to quickly detect faulty components or assembly defects, and can accurately locate defects and defect classification.

Q: Can ICT be regarded as a universal meter?

A: ICT can be regarded as an automated high-level multipurpose meter, and because it has the function of circuit isolation, it can accurately measure the actual value of each component in the circuit.

Q: What is the relationship between ICT and AOI?

A: ICT is mainly carried out by electrical measurement methods, while AOI is carried out by optical image processing technology. Both have their own strengths and complement each other. In the process arrangement, AOI is generally the first, then ICT.

Tags: ICT test
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How to do EMI/EMC Testing in PCBs?

25 10 月, 2024

In the PCB design and testing, there is a common term be mentioned frequently, that is EMI and EMC. Some people may ask that “what is EMI/EMC, why is it be mentioned every time?” Today, BEST team will take you to understand what are they and how to test them. Let’s keep reading.

What are EMI and EMC in PCB?

Before diving into, we should know both EMI and EMC are important elements during the PCB design. Some new PCB projects are failed during testing, because EMI and EMC design is not reasonable.

EMC is short for electromagnetic compatibility. EMC in a PCB is the ability of the PCB to operate in its electromagnetic environment without creating unbearable electromagnetic interference to other devices around it. In general, to achieve an EMC compliant design, engineers need to consider three basic aspects:

Generating unwanted electromagnetic radiation and its propagation.
The vulnerability of designs or components to electromagnetic interference (EMI).
PCB design should not cause intolerable electromagnetic interference on its own.

EMI is short for electromagnetic interference. EMI is unwanted noise or signals generated by electronic devices, which can disrupt other nearby equipment. PCBs, being central to electronics, are often both sources and victims of EMI. Every engineer should follow EMC configuration standards to minimize the total amount of EMI and its impact.

In a word, EMI refers to the generation of electromagnetic interference, while EMC refers to electromagnetic compatibility, that is, how well a device blocks EMI. EMI originates from electromagnetic equipment, and EMC involves equipment that is both anti-interference and non-interference with other equipment.

What Is the Difference Between EMI and EMC Testing?

EMI testing focuses on measuring the interference a device generates. It aims to ensure that the PCB doesn’t emit electromagnetic waves that can interfere with other devices. EMC testing, on the other hand, checks the device’s ability to withstand electromagnetic interference from its environment without losing functionality. Both tests are essential to make sure that your PCB not only works well but also doesn’t cause problems for other systems.

The main difference between EMC tests and EMI is their purpose and method of testing. ‌

Test purpose

‌EMC testing focus on the equipment or system will function properly in an electromagnetic environment and will not cause intolerable electromagnetic disturbance to other equipment. EMC testing includes two aspects: electromagnetic immunity (the ability to resist interference) and electromagnetic emission (not to interfere with other equipment).
‌However, EMI testing focuses on unwanted electromagnetic energy emitted by a device or system that may interfere with the normal operation of other nearby equipment. The purpose of EMI testing is to identify and reduce these sources of interference to prevent interference with other equipment ‌

Testing method

‌EMC test usually includes shielding, grounding, and filtering methods. Shielding is surrounding devices or systems by using conductive materials to reduce leakage of electromagnetic radiation. Grounding is connecting the metal housing and ground to provide a safe electrical circuit loop. Filtering is to reduce unnecessary electromagnetic signal transmission through PCB circuit design.
‌EMI test mainly measuring by the conducted interference and radiation interference of the devices. Conducted interference is interference that travels through a conductive medium (such as a wire), while radiative interference refers to the interference that travels through space.

What Are the Testing Standards for EMI/EMC?

Several global standards guide the EMI/EMC testing process. These include:

IEC 61000 series: This is the most common EMC test standard, covering EMI and EMS (Electromagnetic sensitivity) test methods, limits and units of measure.

EN 55014 series: This is the EU EMC test standard, including:

EN 55014-1: Radiation from household appliances

‌EN 55014-2‌: Radiation immunity of household appliances

‌EN 55032‌ : Interference emission test for multimedia electronic products

‌EN 55035‌ : Immune immunity test for multimedia electronic products

‌GB/T17625 series ‌ : This is China’s EMC test standard, including:

GB/T17625.1-2012‌ : EMC limits Harmonic current emission limits (Input current per phase ≤16A)

‌GB/T17625.2-2007‌ : Limits on voltage variation, voltage fluctuation, and flicker (rated current of equipment per phase ≤16A)

‌GB/T17625.7-2013‌ : Harmonic current limit for conditionally connected devices with rated current ≤75A in a common low-voltage power supply system

‌GB/T17625.8-2015‌ : Harmonic current limit for devices connected to a common low-voltage system with input current greater than 16A but less than 75A per phase

‌GB/T17625.9-2016‌ : Signal transmission emission levels, frequency bands and electromagnetic disturbance levels on low-voltage electrical installations

‌GBZ17625.3-2000‌ : Limits on voltage fluctuations and flickers in low-voltage supply systems for devices with rated current >16A

‌GBZ17625.6-2003‌ : Limits on harmonic currents produced by devices with rated current >16A in low-voltage power supply systems

‌GBZ17625.13-2020‌ : Evaluation of emission limits for unbalanced installations connected to medium voltage, high voltage, and ultra-high voltage power systems

‌GBZ17625.14-2017‌ : Evaluation of emission limits for harmonics, interharmonics, voltage fluctuations and unbalance of nuisance devices connected to low voltage power systems

‌GBZ17625.15-2017‌ : Evaluation of low frequency electromagnetic immunity and emission requirements for distributed generation systems in low voltage power grids

These standards cover a wide range from household appliances to industrial equipment, you can follow one of them according to your specific applications and countries.

How to Conduct an EMI Test?

Before conduct a test, let’s know the testing method. EMI test methods mainly include the following ‌ :

1. Pre-test: EMI testing performed during the design phase to detect and resolve EMI problems early in product design and development. Pre-test can be conducted using computer simulation, or by using actual test equipment.

2. Emission test: It is a test to measure whether electromagnetic waves emitted by equipment meet EMI standards. The emission test can be carried out by field test, half-time test, full-field test and other methods. Commonly used test equipment includes spectrum analyzer, scanning receiver, antenna, etc.

3. Sensitivity test: Common sensitivity testing methods include radiation sensitivity testing and conduction sensitivity testing. radiation sensitivity testing uses a signal generator to generate an electromagnetic field of a specific frequency and intensity. And conduction sensitivity testing involves injecting simulated electromagnetic interference signals on the power or signal lines of the equipment under test.

4‌. Spectrum analysis: By measuring the spectrum of electromagnetic wave to analyze the characteristics of electromagnetic interference.

‌Above are the testing methods of EMI, and here is the steps that how to test it.

Select the right test method

First of all, select a right test method according to the specific test purpose and object. For example, if the emission characteristics of the equipment need to be evaluated, an emission test can be selected; If you need to evaluate the anti-interference capability of the equipment, you can choose sensitivity test.

Use professional equipment

Use professional test equipment, such as spectrum analyzer, signal generator, digital storage oscilloscope, etc., to ensure the accuracy of the test results.

Environment control

When performing sensitivity test, control the test environment to avoid the influence of other electromagnetic interference sources. Tests can be conducted in a shielded room to reduce outside interference.

Data analysis

Detailed analysis of the test data, identify potential sources of electromagnetic interference, and propose improvement measures. Methods such as difference method and potential zeroing method can be used to reduce the influence of interfering magnetic field on measurement results.

EMI/EMC PCB Design Guidelines

1. Ground plane

Because all circuits need to be grounded, the ground plane is the first line of defense against EMI. The following measures can be taken to reduce EMI:

Increase the ground area
Set up the ground plane
Each component should be connected to the ground plane
Each component should be connected to the ground plane or a ground point.
Decoupling capacitor
The ground plane is placed directly below the plane with the signal trace
Digital ground and analog ground should be separated
The ground wire should be as thick as possible
The length of the ground system should be kept to a minimum

2. Power supply design

Improper power supply design will result in greater noise and ultimately reduce product performance. Two main factors that lead to power supply instability:

1) Excessive transient AC current under high-speed switching

2) Inductance exists in the current loop Therefore, the integrity of the power supply should be fully considered in PCB design.

3. PCB layout

a) PCB size

PCB size must be considered. When it comes to oversized boards, the traces must go a long way as the impedance increases, the noise immunity decreases, and the manufacturing cost increases. When the board size is particularly small, it will cause heat dissipation problems and crosstalk is prone to occur between adjacent traces. The recommended PCB size is a rectangle with an aspect ratio of 3:2 or 4:3. In addition, when the board size exceeds 200mm*150mm, the mechanical strength of the board retraction should be considered.

b) Avoid right angles

This has been said many times. Avoid 45° to 90° for vias, traces, etc. When the trace reaches more than 45°, the capacitance will increase.

c) Keep signals separated

Digital circuits, analog circuits, and noise sources should be placed independently on the board, and high-frequency circuits should be isolated from low-frequency circuits. In addition, attention should be paid to the component distribution of strong and weak signals and the direction of signal transmission.

d) Increase the trace width as much as possible

e) Wider trace sizes can effectively reduce radiated emissions.

f) Make the return current path as short as possible and route along the path with the least resistance. The length of the return path should be roughly the same as or shorter than the length of the transmission trace.

4. Component placement

In general, it is best to completely separate analog and digital signals. Being too close can easily lead to problems such as crosstalk. In addition, compatible components should be placed independently to ensure that components do not interfere with each other in space.

5. PCB layer design

In terms of the number of layers, choose the appropriate number of layers. Single-layer PCBs and double-layer PCBs are suitable for medium and low-density wiring or low-integrity circuits. Based on manufacturing cost considerations, most consumer electronic products rely on single-layer PCBs or double-layer PCBs. However, due to their structural defects, they both generate a lot of EMI, and they are also sensitive to external interference. Multi-layer PCBs tend to be more used in high-density wiring and high-integrity chip circuits. Therefore, when the signal frequency is high and the electronic components are densely distributed, a PCB with at least 4 layers should be selected. In multi-layer PCB design, the power layer and the ground layer should be specially arranged, and the distance between the signal line and the ground line should be reduced.

6. EMI shielding

Shielding and filtering can minimize the impact of EMI. Some shielding and filtering options include:

Component and PCB shielding
Low-pass filtering
Cable shielding

7. Trace routing

Put the current signals with the same output but opposite directions in parallel to eliminate magnetic interference. Discontinuities in printed leads should be minimized. For example, the lead width should not change abruptly and the lead angle should not exceed 90°.

8. Routing design

The power line, ground line, and traces on the circuit board should maintain low impedance to high-frequency signals. When the frequency remains so high, the power line, ground line, and circuit board traces all become small antennas responsible for receiving and transmitting interference. To overcome this interference, it is more important to reduce the high-frequency impedance of the power line, ground line, and circuit board traces than to increase the filter capacitor. Therefore, the traces on the circuit board should be short, thick, and evenly arranged.

9. Decoupling and grounding

The proper placement of decoupling capacitors and the application of the inductor capacitor energy storage function make it possible to provide current to the device at the moment of switching. In a DC loop, load changes can cause power supply noise. The decoupling capacitor configuration can block the noise generated by load changes. For electronic equipment, grounding is a key method to control interference. If grounding is properly combined with shielding measures, most interference problems will be solved.

Above all are the key points when design pcb, hope you can take them in mind and use in your actual design phase.

Tags: EMC, emc test, EMI test
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What is cem1 PCB?

24 10 月, 2024

CEM1 PCB is a composite epoxy metal-based copper-clad laminate. It is made of flame-retardant epoxy resin impregnated paper or glass fiber cloth as the substrate, covered with copper foil on one side, and hot-pressed. CEM1 PCB has good mechanical strength, electrical properties and heat resistance, and is suitable for the manufacture of various electronic devices.

What is a CEM composite epoxy material?

CEM composite epoxy material is a material used for printed circuit boards (PCBs), mainly composed of epoxy resin, glass fiber cloth, wood pulp paper and copper foil. Its main features are excellent mechanical processing performance, lower cost than glass fiber cloth copper-clad laminate, and better performance than paper-based copper-clad laminate.

Types and applications of CEM composite epoxy materials:

CEM composite epoxy materials mainly include types such as CEM1 and CEM-3. CEM1 composite materials are made of glass fiber fabric surface and paper core combined with epoxy resin, and are mainly used in the printed circuit board industry.

CEM-3 is a composite copper-clad laminate that uses glass cloth and glass felt as a composite substrate. Unlike FR-4, its production process is similar to FR-4, but it uses a different substrate.

What type of PCB is FR4?

FR4 is a copper-clad laminate that is mainly used in printed circuit board (PCB) manufacturing.

FR4, which stands for Flame-Retardant 4, is a composite material made of glass fiber and flame-retardant epoxy resin. It has excellent flame retardant properties and stable electrical properties, so it is widely used in the electronics industry.

FR4 board is mainly made of quadrifunctional epoxy resin plus filler and glass fiber cloth. Epoxy resin has good adhesion and electrical insulation, while glass fiber cloth provides mechanical strength and dimensional stability.

The specification standard of FR4 board is formulated by NEMA (National Electrical Manufacturers Association), where FR represents the flame retardant grade.

FR4 copper clad laminate is divided into different grades according to performance and quality, mainly including:

FR-4 A1 grade copper clad laminate: mainly used in high-end electronic products such as military industry, communications, computers, digital circuits, industrial instruments and meters, and automotive circuits.

FR-4 A2 grade copper clad laminate: suitable for ordinary computers, instruments and meters, high-end home appliances and general electronic products, and its performance indicators meet the needs of general industrial electronic products.

FR-4 A3 grade copper clad laminate: mainly used in the home appliance industry, computer peripheral products and general electronic products. On the premise that the performance meets the requirements, the price has a competitive advantage.

FR-4 A4 grade copper clad laminate: It is a low-end material, but it can still meet the needs of ordinary home appliances, computers and general electronic products, and its price is the most competitive.

FR-4 B grade copper clad laminate: The quality stability is poor, suitable for smaller circuit board products, and the price is the lowest.

In summary, FR4 is a high-performance copper clad laminate material, which is widely used in various electronic products and is favored for its excellent flame retardant properties and stable electrical properties.

What is the difference between CEM1 and FR4?

The main differences between CEM1 and FR4 are in terms of material composition, mechanical properties, electrical properties, heat resistance and cost.

Material composition and manufacturing process:

FR4: It is composed of glass fiber and epoxy resin. Its manufacturing process is mature and the cost is relatively low, so it is widely used.

CEM1: It is a composite epoxy resin material with wood pulp fiber paper or cotton pulp fiber paper as the core material, covered with glass fiber cloth on the surface, and impregnated with flame-retardant epoxy resin. Compared with FR4, CEM1 has slightly inferior mechanical properties and heat resistance, but lower cost.

Mechanical properties and heat resistance:

FR4: It has high mechanical strength and rigidity, suitable for complex electronic equipment and structures. It has good heat resistance and can remain stable at higher temperatures.

CEM1: It has slightly lower mechanical strength and is suitable for electronic products with low performance requirements. Its heat resistance is also relatively poor.

Electrical properties:

FR4: has excellent electrical properties, including high insulation resistance and low dielectric constant, suitable for electronic devices with high frequency and high-speed transmission.

CEM1: The electrical properties are slightly inferior to FR4, and it is not suitable for high-frequency applications.

In summary, FR4 performs better in mechanical properties, electrical properties and heat resistance, and is suitable for electronic devices with high performance requirements; while CEM1 has more advantages in cost and is suitable for electronic products with low performance requirements.

What are the advantages of CEM1 PCB?

The main advantages of CEM1 PCB include the following aspects:

Excellent mechanical properties: CEM1 PCB has excellent mechanical properties, and its impact force can reach 0.093 inches. Compared with paper grades, CEM1 is easy to stamp and has higher bending strength.

High cost-effectiveness: The cost of CEM1 PCB is lower than that of glass fiber cloth copper clad laminate, so it has significant advantages in cost control.

Good electrical performance: The electrical performance of CEM1 PCB is also excellent, suitable for various electronic devices, especially in the LED lighting market, CEM1 is able to achieve the best balance between heat dissipation performance and PCB cost.

Wide range of applications: CEM1 PCB is widely used in the printed circuit board industry, especially in some low-end and mid-range products.

What are the disadvantages of CEM1 PCB?

Mechanical durability: CEM1 printed circuit board lacks good mechanical durability.

Production applicable type: CEM1 can be used to produce single-sided PCBs because its laminate is not compatible with through-holes.

Fragility: PCBs produced by CEM1 are very fragile and can easily break if not handled properly.

Substitutability and limitations: FR-4 can be used to replace CEM1. But in case FR-4 needs to be replaced, CEM1 can only replace single-layer FR-4 PCBs with limited functions.

Why is CEM1 PCB single-layer?

The main reason why CEM1 PCB is single-layer is due to its material properties and cost-effectiveness.

CEM1 PCB is a single-layer printed circuit board. Its material properties determine that it can only be made into a single-layer structure. CEM1 material is mainly composed of glass cloth and epoxy resin. This material structure makes the PCB board have only one conductive layer.

Although technological advances have made multi-layer PCBs possible, PCBs made of CEM1 materials still maintain a single-layer structure, mainly because of its cost-effectiveness and design complexity.

The design and manufacturing of single-sided PCBs are relatively simple and low-cost, suitable for low-density design requirements. Since there is only one conductive layer, more winding is required during wiring design, but this is acceptable in low-density designs.

In addition, the manufacturing process of single-sided PCBs is relatively fast and low-cost, which is one of the reasons why it is widely used.

What are the applications of CEM1 PCB?

Simple applications and LED lighting: It can be used to make simple applications such as toys, remote controls, calculators, and home appliances. At the same time, headlights, indicator lights, and brake lights in LED lighting can also be made of CEM1 PCBs.

Computer Components: Computers are sensitive to heat, and LED CEM1 PCBs can conduct heat effectively, so computer components such as CPUs, floppy disk drives, and power supply units are made of them.

Industrial and Electronic Equipment: Used in the production of industrial controls, converters, instrumentation, UPS systems, hard disks, and telephone systems.

Medical Field: Tools used to perform surgeries are made of CEM1 LED PCBs, and even medical scanning technology uses such PCBs to manufacture scanning equipment.

As a special type of PCB, CEM1 PCB is widely used in the electronics industry for its good mechanical strength, electrical properties, heat resistance, and low cost. As electronic equipment continues to develop, CEM1 PCBs will also continue to innovate and develop to meet the needs of electronic equipment.

Tags: CEM1 PCB, fr4, PCB
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Aerospace PCB Assembly Guide | PCBA & Box Building

24 10 月, 2024

What is Aerospace PCB Assembly?

Aerospace PCB assembly refers to the intricate process of manufacturing printed circuit boards (PCBs) specifically for aerospace systems, including aircraft, spacecraft, satellites, and other related avionics systems. These boards are vital for controlling critical systems in extreme environments, where traditional electronic components would fail. Aerospace PCBs are engineered with precise attention to durability, signal integrity, and longevity to ensure reliable operation over long periods, even in the most hostile conditions like extreme temperatures, vibrations, and radiation.

The assembly process includes component placement, soldering, testing, and verification to ensure the PCBs meet strict aerospace industry standards. Due to the high-stakes nature of aerospace applications, each PCB must be built with the highest degree of precision and undergo rigorous testing to ensure it can withstand the operational conditions of the specific aerospace application.

Aerospace PCB Assembly Guide | PCBA & Box Building

Why does Aerospace PCB Assembly Need High Reliability?

Aerospace PCB assembly requires exceptionally high reliability due to the mission-critical nature of the systems they support. Unlike consumer electronics, where failures might lead to inconvenience, failures in aerospace systems can be catastrophic, leading to loss of life, property, or the failure of multimillion-dollar space missions. Once a satellite, spacecraft, or aircraft is deployed, accessibility to repair faulty components is extremely limited. So that aerospace PCBs function flawlessly for years, or even decades, without failure.

In addition to inaccessibility, aerospace electronics face harsh environmental conditions such as extreme temperatures, radiation, shock, and vibration. These conditions demand that PCBs operate continuously under stress without compromising their performance. High-reliability standards ensure the PCBs’ long-term stability and functionality in these demanding environments. Aerospace components must be high quality, fail-safe, and undergo extensive testing for performance, durability, and resilience.

What Grade of IPC Standard Should Aerospace PCB Assembly Follow?

IPC standards are a widely used term in the electronics industry that covers all aspects of electronic product design, including the acceptability of printed circuit boards, material requirements, and more. IPC standards establish standards from all aspects, as long as manufacturers strictly implement the standards, product quality and reliability are naturally guaranteed.

Aerospace PCB assembly needs to meet the requirements of high reliability, high quality and high performance, so during the production process, it should comply with IPC-6012 Level 3 standards. IPC-6012 is a performance specification document that defines the default requirements and specifications for each class of PCB. Among them, Class 3 PCBs have tighter tolerances and are commonly used in military applications, medical devices, and the aerospace industry. The IPC-6012 Level 3 standard ensures that the PCB can also ensure the reliable start-up and operation of the equipment in harsh environments, such as high temperature, low temperature, vibration and other extreme conditions can still work.

In addition to IPC-6012, IPC-610 Class 3 is critical for ensuring the highest quality workmanship in aerospace electronics as well. In the IPC-610 standard, class 3 defines the acceptance criteria for high-reliability electronics, including tight tolerances, high-quality soldering, and thorough inspections.

Industry Standards for Aerospace PCB Manufacturing

Aerospace PCB manufacturing must adhere to several industry-specific standards to ensure reliability and safety.

ISO9001

It is an internationally recognized quality management system standards designed to help organizations continue to provide products or services that meet customer and applicable legal and regulatory requirements through a systematic approach. It is the code of conduct that governs our production process.

AS9100

Another essential standard is AS9100, which is a widely recognized quality management system tailored specifically for the aerospace industry. It covers every aspect of the aerospace PCB production process, from material selection to assembly, testing, and delivery.

MIL-PRF-31032

It is one of the most significant standards is MIL-PRF-31032, which governs the qualification of printed wiring boards used in military and aerospace applications.

RoHS

PCBs for aerospace applications must also comply with RoHS (Restriction of Hazardous Substances) regulations, particularly in Europe, to ensure the environmental safety of electronic components. Additionally, aerospace PCBs undergo specific testing procedures, such as thermal cycling, vibration testing, and humidity resistance, to ensure they meet operational standards.

Best Technology certificated by ISO9001, ISO13485, IATF16949, AS9001, RoHS and some other certifications about manufacture. We are dedicated to provide customers with “High mixed, low volume, fast delivery and high quality” PCB and PCBA products. At Best Technology, you get a sense of value for money!

Common PCBA Modules or Systems for Aerospace Electronics

Aerospace electronics rely on various specialized PCBA modules and systems to ensure efficient and reliable operation in mission-critical environments. These systems are essential in everything from flight control to communication, navigation, and power management in aircraft, satellites, and spacecraft. Below are some of the most common PCBA modules or systems used in aerospace electronics:

1. Avionics Control Systems

Avionics control systems are the backbone of modern aerospace technology, responsible for managing and controlling various systems in aircraft and spacecraft. They handle critical functions such as navigation, communication, and onboard sensors, providing real-time data to pilots and flight computers.

2. Power Management Systems

Power management systems in aerospace electronics regulate the distribution and control of electrical power across the aircraft or spacecraft. These PCBA modules are designed to manage the onboard electrical grid. In some subsystems, they provide a stable power supply, such as for communication equipment, control systems, and sensors.

3. Flight Control Systems

Flight control systems are responsible for managing an aircraft’s or spacecraft’s attitude, direction, and speed. The PCBA modules within these systems process data from various sensors (like gyroscopes and accelerometers) and use it to adjust control surfaces or thrusters.

4. Radio Communication Systems

It enables the communication between the aircraft and ground control. RF (Radio Frequency) modules, transceivers, and antenna control units are common PCBAs in communication systems. Aerospace communication systems are engineered to handle long-distance transmission and are resistant to environmental interference, such as radiation or electromagnetic noise.

5. Navigation Systems

Navigation systems in aerospace electronics guide aircraft and spacecraft to their destinations using data from GPS satellites, inertial navigation systems (INS), and other sources. The PCBAs in navigation systems are responsible for processing this data and providing accurate location, speed, and altitude information.

6. Radar and Sensor Systems

They are the most important parts in the aerospace applications, like collision avoidance, terrain mapping, and weather monitoring. They can process large amounts of data quickly and reliably, often using digital signal processors and field-programmable gate arrays (FPGAs) to handle real-time processing.

7. Environmental Control Systems (ECS)

Environmental control systems are responsible for maintaining optimal cabin and equipment conditions within an aircraft or spacecraft. These systems monitor and regulate air pressure, temperature, and humidity. The PCBAs used in ECS modules often featuring sensors that track environmental parameters and control systems that adjust them accordingly.

8. Data Acquisition Systems

Data acquisition systems collect and process data from various subsystems and sensors in aerospace applications. These PCBA modules are integral in spacecraft, aircraft, and satellites, enabling real-time data monitoring, analysis, and recording. Data acquisition PCBAs are designed to interface with different sensors, process data quickly, and transmit it to central control systems for further analysis. These systems must be reliable and capable of operating in high-altitude or space environments where temperatures and radiation levels can be extreme.

9. Power Distribution Units (PDUs)

Power Distribution Units (PDUs) manage the flow of electrical power to various subsystems within an aircraft or spacecraft. The PCBAs in PDUs ensure that power is efficiently distributed to essential systems, and they often include built-in protections against power surges, overloads, and short circuits.

Best materials for Aerospace PCB Assembly

Aerospace PCB mainly used high reliability and high temperature materials. Common material types are the following:

High temperature substrate

Because aerospace electronic equipment is often in a high temperature environment, it is necessary to use high temperature substrate, such as polyimide (PI) and polytetrafluoroethylene (PTFE).

Refractory materials

The aerospace field has strict fire safety requirements, so it is necessary to use good flame

retardant materials, such as polystyrene (PS) and Australian flame retardant epoxy resin.

Corrosion resistant materials

There are some corrosive substances in the aerospace environment, so it is necessary to use materials with good corrosion resistance, such as special polyamides and special coatings.

High electrical performance materials

In aerospace applications, circuit boards are required to have good electrical properties, including high impedance, low dielectric constant and low dissipation characteristics, so materials such as high frequency glass fiber cloth (FR4), polyimide (PI) and polytetraoxyethylene (PTFE) are often used.

Aerospace PCB Assembly design standards

Designing PCBs for aerospace applications requires adherence to strict design standards that ensure optimal performance under harsh conditions. These design standards focus on several critical factors:

Signal Integrity

Aerospace PCBs must be designed to minimize signal degradation, ensuring accurate data transmission. High-speed signal transmission lines must be optimized for impedance control and reduced electromagnetic interference (EMI).

Thermal Management

Effective heat dissipation is crucial to prevent overheating in aerospace PCBs. The design must incorporate features such as metal cores or heat sinks to manage thermal loads efficiently.

Vibration and Shock Resistance

Aerospace PCBs are subject to extreme vibration and shock during flight or launch. The design must include mechanical reinforcements and vibration-dampening measures to protect the integrity of components and solder joints.

EMI Shielding

Aerospace environments are susceptible to electromagnetic interference, which can disrupt signal integrity. Proper shielding techniques, such as ground planes and shielded traces, are essential to reduce EMI and ensure reliable signal performance.

Component Placement

Components must be strategically placed to ensure signal integrity, reduce noise, and improve overall PCB performance.

Best Technology is a professional PCB & PCBA manufacturers in military, aerospace and medical, over 70% of our engineers have worked in PCB industry for more than 10 years. We have mature technology and advanced testing equipment to ensure the highest quality while maintain fast delivery. Trust us, we can be your most reliable PCB supplier in China and Vietnam.

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