Can a Diode Be Used as a SWR Power Meter?

November 16th, 2024

Standing Wave Ratio (SWR) power meters are essential for ensuring your radio equipment operates efficiently. These devices help users monitor power and maintain good transmission quality. Some wonder if diodes, common in various electronic circuits, can play a role in these meters. This article explores SWR power meters, their usage, and whether diodes can be used for this purpose.

Can a Diode Be Used as a SWR Power Meter?

What is an SWR Power Meter?

An SWR power meter measures the ratio of forward power to reflected power in a transmission line. This ratio helps determine how efficiently the transmitter’s power is delivered to the antenna. A good SWR ensures that most of the energy reaches the antenna, minimizing losses and protecting equipment.

An SWR value close to 1:1 indicates almost all power is transmitted with minimal reflection. Higher values show more power is bouncing back, which can lead to damage or poor performance.

How Does an SWR Power Meter Work?

SWR power meters are installed between the transmitter and the antenna. They measure forward power and reflected power. The forward power travels from the transmitter to the antenna, while reflected power is what returns due to impedance mismatches.

The meter calculates the SWR by comparing these two readings. Meters use directional couplers, sensitive enough to differentiate the power flows. The main goal is to ensure most energy travels forward with minimal loss.

How to Read an SWR Power Meter?

Reading an SWR meter is straightforward. Here’s how:

Power On: Turn on the transmitter at low power.
Set to Forward: Set the meter to the forward position and take note of the power.
Switch to Reflect: Change the meter to read the reflected power.
Check Ratio: Compare both readings to get the SWR.

A good reading is typically below 2:1. If it’s higher, adjustments to the antenna or transmission line may be needed.

How to Use an SWR Power Meter?

Using an SWR meter helps ensure you’re not wasting energy. Follow these steps:

Connect Properly: Place the meter between the transmitter and the antenna.

Select the Band: Choose the frequency you plan to transmit.

Adjust Power Levels: Start with lower power and increase as needed.

Read and Interpret: Note both forward and reflected power.

Adjustments can include changing the length of the transmission line or repositioning the antenna. These small tweaks help maintain a safe SWR level, ensuring longer equipment life.

Where Do You Put an SWR Meter?

Placement is critical for accurate SWR readings and maintaining optimal performance in your transmission setup. An SWR meter must be positioned directly between the transmitter and the antenna to accurately measure both the forward and reflected power.

Close to the Transmitter

Ideally, the SWR meter should be placed as close to the transmitter as possible. This ensures that any potential loss or reflection occurring within the cable before the meter is accounted for in the measurement. Keeping it close to the transmitter also reduces the risk of incorrect readings due to cable impedance variations.

Inline Connection

The SWR meter needs to be connected inline with the coaxial cable running from the transmitter to the antenna. Make sure to insert the meter so that the “Transmitter” or “TX” side of the meter is connected to the radio, and the “Antenna” or “ANT” side is connected to the feed line that goes to the antenna.

Ensure Firm Connections

A secure connection is essential to avoid power leaks or signal degradation. Loose or improperly connected cables can distort readings and give false impressions of your SWR levels.

Temporary vs. Permanent Placement

If you are conducting a one-time SWR check, a temporary connection may be enough. For continuous monitoring, you can install the meter as a permanent fixture in your transmission line. Permanent placement is particularly useful for setups where you frequently switch bands or adjust power levels and need constant feedback.

Minimize Cable Lengths

Extra cable between the transmitter and the SWR meter can introduce unwanted losses and impedance mismatches. Keeping the cable length minimal between the devices helps maintain the true characteristics of the transmission line, ensuring your SWR reading is as accurate as possible.

Environment Considerations

Place the SWR meter in a location that is easy to read and free from extreme temperature or humidity. Environmental factors can affect the meter’s internal components over time, leading to inaccuracies. Additionally, avoid areas with strong electromagnetic interference, as it can distort the meter’s readings.

Can a Diode Be Used as an SWR Power Meter?

A diode can indeed play a part in an SWR power meter but not as the main measuring tool. Diodes are vital for rectifying alternating current (AC) into direct current (DC). In SWR meters, they detect voltage changes by converting RF signals into readable DC levels.

In simpler meters, diodes are part of the directional coupler circuit. This circuit separates forward and reflected signals. The diode’s role is to sense these signals and help display power levels. However, while they’re essential in detecting changes, diodes alone cannot fully replace an SWR power meter. They must work alongside other components for accurate results.

Do I Need a Diode on a Relay?

Relays switch circuits by opening and closing contacts. Sometimes, adding a diode across a relay’s coil is necessary. This type of diode, known as a flyback or snubber diode, protects against voltage spikes. When the relay is de-energized, the collapsing magnetic field can create high-voltage spikes. A diode helps by providing a path for the current, preventing damage to other parts.

In SWR meters, if relays are used to switch bands or paths, diodes could prevent potential damage. This adds safety to circuits, extending the life of the components.

How Do I Know if My SWR Meter Is Bad?

An SWR meter can fail over time. Here are signs that may indicate a problem:

Inconsistent Readings: If your meter shows fluctuating or unrealistic results, it could be faulty.

Zero Reflection: If the meter never shows any reflected power, even with known mismatches, it’s likely not functioning.

Physical Damage: Broken components or burnt circuits can lead to inaccurate readings.

Calibration Issues: A poorly calibrated meter may not reflect true power levels.

If you suspect a problem, testing the meter with known setups or professional recalibration might be necessary.

SWR power meters play a critical role in ensuring efficient power transmission. While diodes can be part of their design, they aren’t standalone SWR meters. Diodes help in detecting voltage changes, contributing to the overall accuracy of readings. Proper use and placement of an SWR meter ensure good transmission quality and equipment longevity. If you’re considering adding diodes to other components, such as relays, they can offer valuable protection.

Choose reliable SWR meters to safeguard your transmission setup and maintain optimal performance. If accuracy and durability matter, it’s worth investing in well-calibrated tools that use components like diodes effectively.

Tags: swr power meter
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A Comprehensive Analysis of Soldering Defects

November 15th, 2024

PCB assembly involves mounting electronic components onto bare PCB boards to create semi-finished devices. In this process, soldering is the initial and essential step. Today, we’ll discuss the common soldering issues that arise during PCB assembly and how to prevent them.

Soldering Defects

Soldering defects are issues that arise when joints do not meet the expected quality standards. These defects can impact the functionality, reliability, and longevity of a product.

Some typical issues include software design flaws, overheating, incorrect component placement, and power supply issues. Every manufacturer should be aware of these potential pitfalls to ensure reliable and efficient PCB assembly.

A Comprehensive Analysis of Soldering Defects

Why Soldering Defects Occur?

Soldering defects can occur during the assembly process, potentially leading to wasted resources, damaged reputation, product malfunctions, and most critically, loss of time—frustrating both manufacturers and clients. However, by understanding common PCB failure causes, you can address them quickly and effectively.

‌‌Poor Solderability of Holes Vias

Poor solderability of holes can lead to soldering defects, affecting the parameters of components in the circuit and causing unstable connections between components and inner layers in multilayer boards. This can result in the failure of the entire circuit.

Soldering Temperature

The soldering temperature, whether too high or too low, and inadequate surface cleanliness can affect the soldering quality. When the temperature is too high, the solder spreads quickly and is prone to oxidation, leading to defects. When the temperature is too low, the solder may not fully melt, resulting in weak joints.

Flux Issues

The quality and application of flux also impact soldering quality. Insufficient or poor-quality flux can cause poor wetting, resulting in weak and dull solder joints. Excessive flux may lead to overheating, causing rough joint surfaces.

Solder Issues

The quality and fluidity of the solder directly affect the soldering outcome. Poor-quality solder or solder with low fluidity can lead to weak and dull joints, or defects where the solder covers less than 80% of the pad.

PCB Design Issues

Poor PCB design can also result in soldering defects. For example, excessively long traces can increase impedance and noise, affecting soldering quality. Components generating heat without proper heat dissipation can also lead to soldering issues.

Operational Issues During Soldering

Problems such as insufficient soldering time, improper temperature control, or loose component leads during soldering can all result in defects.

How many types of soldering defects are there?

There are several types of soldering defects that can occur during the PCB assembly process. Here is a list of common soldering defects:

Cold Joints
Bridging
Insufficient Solder
Solder Balls
Voids
Cracked Joints
Non-wetting
Tombstoning
Pin Holes or Blow Holes
Oxidation Defects
De-wetting
Component Misalignment
Solder Splashes
Excessive Solder

How Do You Troubleshoot Soldering? -One by One

Cold Joints

Cold joints occur when the solder doesn’t heat properly, resulting in weak, dull, and rough connections. To prevent this, use a soldering iron with adequate power and maintain the correct soldering temperature (typically between 350°C to 400°C for leaded solder). Ensure that both the pad and component lead are evenly heated before applying solder. The solder should flow smoothly around the joint. Using a clean, well-tinned soldering iron tip ensures efficient heat transfer. Additionally, avoid moving the joint before the solder has fully solidified.

Bridging

Bridging happens when excess solder connects adjacent leads, creating shorts. To avoid this, apply an appropriate amount of solder paste using a stencil with the right thickness. Use a fine-tipped soldering iron or a hot air rework tool to apply heat precisely. If bridging occurs, use a desoldering braid or a vacuum desoldering tool to remove excess solder. Practice steady hand movements when applying solder manually and avoid dragging the soldering tip across pads.

Insufficient Solder

Insufficient solder leads to weak joints that can easily break. To fix this, ensure that enough solder paste is applied during the assembly process. Check that the soldering tip transfers enough heat to allow solder to flow adequately across the pad and component lead. If needed, reflow the joint by reheating and adding a small amount of solder to improve coverage and strength.

Solder Balls

Solder balls are tiny spherical particles that can detach and create shorts. To prevent this, maintain a proper reflow profile that allows gradual heating and cooling. Ensure that the solder paste is of high quality and free from contamination. Clean the PCB surface thoroughly to remove dust and oil. Control the application of solder paste to prevent excessive paste that could splatter during heating.

Voids

Voids are gaps in the solder joint caused by trapped gas or flux residue. To minimize voids, pre-bake PCBs to remove moisture that can turn into steam during soldering. Use high-quality, low-residue flux and ensure even application. Adjust the reflow profile to give enough time for gases to escape before the solder solidifies. This reduces the chances of void formation.

Cracked Joints

Cracked joints can form due to rapid cooling or mechanical stress. Allow the solder joint to cool naturally without sudden air exposure. Ensure the PCB is not moved or subjected to vibrations while the solder is cooling. Choose solder materials with good thermal expansion properties to withstand temperature changes. For wave soldering, ensure that components are secure on the PCB before the process starts.

Non-wetting

Non-wetting occurs when the solder does not adhere properly to the pad or lead. This issue is often due to surface contamination or oxidation. Clean the board thoroughly with isopropyl alcohol or a PCB cleaner to remove oils, oxidation, or other contaminants. Use high-quality flux that promotes wetting and re-tin oxidized component leads before soldering. Ensure that the soldering temperature is within the recommended range for proper flow and adhesion.

Tombstoning

Tombstoning happens when one side of a component lifts off the PCB due to uneven heating. This can be addressed by ensuring an even reflow profile where both sides of the component are heated simultaneously. Verify that the solder paste deposit is balanced on each pad to prevent uneven solder melting. Additionally, using smaller components with balanced thermal mass can help prevent tombstoning.

Pin Holes or Blow Holes

Solution: Pin holes or blow holes result from gas escaping during soldering. To reduce this, pre-bake PCBs at a low temperature (e.g., 100°C for one hour) to remove moisture. Use flux that contains fewer volatile components. Optimize the reflow profile to allow flux and trapped gases to escape before the solder solidifies. Ensure that the soldering environment has low humidity to further minimize gas formation.

Oxidation Defects

Oxidation occurs when solder joints are exposed to air for too long before the soldering process. To prevent oxidation, apply flux shortly before soldering to create a barrier against air. Use a nitrogen atmosphere in reflow ovens to reduce oxidation. Regularly clean the soldering tip and apply fresh solder to prevent oxidation on the tip itself.

De-wetting

De-wetting occurs when the solder initially wets the pad but retracts, leaving an uneven surface. This can be caused by contamination or poor-quality solder. Ensure the soldering surface is free from contaminants and oxides by cleaning it with an appropriate cleaner. Use high-quality solder and maintain an optimal soldering temperature to allow proper wetting without over-stressing the solder.

Component Misalignment

Misaligned components can lead to poor connections and defects. Use automated pick-and-place machines for accurate component positioning. Check component alignment manually before reflow if placing by hand. During reflow, use alignment aids or fixtures to ensure components stay in place. Verify that the solder paste stencil and reflow settings are precise for even solder distribution.

Solder Splashes

Solder splashes are small splatters of solder that can lead to shorts or contamination. To prevent this, maintain a consistent reflow profile and avoid sudden movements during the soldering process. Check that solder paste is applied evenly, without excess. Ensure that the soldering environment is stable and free of vibrations.

Excessive Solder

Excessive solder can create thick joints or bridges between pads. Apply solder paste using a stencil with an appropriate aperture size for precise control. Train operators to apply the right amount of solder during manual soldering. Use a fine-tipped soldering iron for better control and to prevent large, excessive solder deposits.

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Tags: SMT, solder defects
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When to Use Clean or No Clean Flux?

November 14th, 2024

Definition of Solder Paste Flux

Solder paste flux ‌ is a material used in the field of electronic welding, usually consisting of tin, silver, copper, nickel and other metal powders as well as flux and solvent components. It divided into clean flux and no clean flux. It can form a thin layer of solder paste on the surface of the circuit board, which has strong adhesion and electrical conductivity, and can make electronic components and circuit boards quickly welded together. The ingredients of solder paste flux include:

Solvent: Used to dissolve solid or liquid components and regulate uniformity.
Resin: Increase the adhesion of solder paste, prevent PCB reoxidation after welding.
Activator: Remove oxidized substances from the through hole surface layer of PCB copper film and parts SMT patch, reduce the liquid surface tension of tin and lead.
Thixotropic agent: Adjust the viscosity of solder paste to prevent tailing and adhesion.

There are two common solder paste flux types used in the PCB assembly:

Water-soluble flux: large solubility, strong activity, residue after welding can be cleaned with water. It also called cleaned flux.
No-cleaning flux: little residue after welding, non-toxic and tasteless, does not pollute the environment.

No Clean Flux vs. Clean Flux

When working with PCBs, the choice between no clean flux and clean flux can greatly impact the quality, reliability, and cost of the final product. Understanding their properties, benefits, and appropriate use cases helps in making informed decisions for different soldering scenarios.

Composition and Characteristics

Clean Flux: This type of flux contains active ingredients designed to ensure thorough cleaning during the soldering process. Its composition includes stronger activators that effectively remove oxides and contaminants from the metal surfaces being soldered. However, the resulting residue left behind is often corrosive or conductive. Thus, it must be cleaned after soldering to prevent damage to the circuit or degradation of electrical performance.

No Clean Flux: As its name implies, no clean flux is formulated to leave minimal, non-corrosive, and non-conductive residue. The formulation uses milder activators that still assist in the soldering process but are designed to burn off or remain as safe deposits. These residues do not interfere with the circuit’s electrical properties, allowing the assembly to be used without further cleaning. The residue left is typically clear and dry, posing minimal risk under normal conditions.

Performance and Suitability

Clean Flux is ideal for applications that demand high reliability and minimal contamination. Examples include:

High-frequency circuits: Residue from clean flux can interfere with signal integrity. Removing these residues ensures optimal performance.
Sensitive electronic devices: Medical devices or aerospace electronics that operate in critical conditions benefit from using clean flux due to the necessity of pristine circuit conditions.

No Clean Flux, on the other hand, is suited for:

Consumer electronics: Phones, computers, and household gadgets that do not operate under extreme conditions.
Cost-sensitive production: Mass production benefits from the time and expense saved by eliminating the cleaning step.
Environmentally conscious manufacturing: With no post-soldering cleaning required, the use of chemical solvents is minimized.

Clean Flux Advantages:

Superior Cleanliness: Ensures there is no residue to attract moisture or create pathways for current leakage.

Reliability in Critical Applications: Guarantees circuits remain in top condition, preventing issues in high-risk environments.

Certification Compliance: Many stringent industry standards and certifications require flux to be cleaned for safety and performance assurance.

Disadvantages of Clean Flux:

Additional Steps: Post-soldering cleaning adds time, labor, and costs.

Environmental Impact: Cleaning often involves chemical solvents that must be disposed of properly.

Equipment Needs: Special machinery like ultrasonic cleaners may be required to remove flux residues effectively.

No Clean Flux Advantages:

Time and Cost Savings: Speeds up the production process by eliminating the need for cleaning.

Reduced Chemical Use: Contributes to a cleaner manufacturing process by avoiding harsh cleaning agents.

Simplified Workflow: Reduces the complexity of production lines by removing an extra step.

Disadvantages of No Clean Flux:

Limited High-Reliability Use: In high-frequency or high-voltage circuits, even minimal residue could pose potential risks.

Residue Visibility: While safe, residues can still be visible, which might not be acceptable for circuits requiring visual inspection.

Selective Suitability: Not ideal for all applications, especially those where long-term exposure to various environmental factors could react with even benign residues.

Application Considerations

Clean Flux is the better choice when:

The circuit board is part of a medical device, aerospace system, or any application where safety and precision are crucial.

The project involves sensitive circuits that cannot tolerate any contaminants, no matter how minimal.

Certification bodies require absolute cleanliness for approval.

No Clean Flux is more suitable when:

Production efficiency is a priority, as in consumer electronics manufacturing.

The board does not require visual perfection or meets the tolerance for low-level residues.

Environmental policies favor reduced chemical use and waste.

Why is it Called No Clean Flux?

The term no clean flux reflects its primary feature: no mandatory post-soldering cleaning. This type of flux is made with a formulation that leaves behind minimal, safe residues. The composition typically includes a mix of weak organic acids and solvents that burn off or leave a thin, inert layer during the soldering process. This layer is non-conductive and won’t affect the circuit’s performance, eliminating the need for additional cleaning steps.

This type of flux gained popularity as manufacturing practices evolved to become faster and more cost-efficient. The avoidance of cleaning also means fewer chemicals are used, supporting environmentally friendly production lines. The convenience of no clean flux does not compromise soldering quality in most cases, making it a go-to choice for many electronics manufacturers.

What Happens if You Don’t Clean Flux on a PCBA?

Not cleaning the flux on the PCBA can cause a range of problems including reduced electrical performance, corrosion, leakage, short circuit, etc. ‌

First of all, incomplete flux cleaning can significantly reduce the electrical performance of the circuit. Residual flux may cause resistance to increase, capacitance to decrease, and in severe cases, complete circuit failure. In addition, residual flux may cause metal corrosion and leakage, increasing the risk of circuit damage and short circuit. Improper cleaning will also affect the insulation performance of the circuit, resulting in reduced insulation impedance, which may cause leakage or more serious circuit failure.

When the temperature changes, the flux residue may also cause the thermal expansion mismatch between the solder joint and the circuit board, causing the solder joint to crack or fall off, and eventually lead to circuit failure. In addition, the residual flux may form electron movement during electrification, resulting in short circuit and product failure ‌. Especially in modern electronic products, the pad spacing is getting smaller and smaller, and the presence of residue increases the possibility of short circuit.

When to Use No Clean Flux?

No clean flux fits well with everyday consumer electronics, where quick production and cost savings are key. It is useful for circuits where non-conductive residue won’t impact performance, like in standard home appliances or low-sensitivity equipment. Some typical situations are suitable to use no-clean flux, like:

Environment with very low requirements for residue after soldering: no-clean flux has very little residue after welding, and can reach the standard of ionic cleanliness without cleaning. It is suitable for environments with very high requirements for residue after welding.
Occasions with high environmental requirements ‌ : no-cleaning flux does not contain halide active agent, no need to clean, reduce the discharge of waste gas and wastewater, in line with the requirements of environmental protection.
Project requires high economic benefit: the use of no-cleaning flux can reduce the input of cleaning equipment and cleaning solvent, reduce the production cost.
Low odor requirements situation: the traditional loose-scented flux has a larger odor, while the no-clean flux has a smaller odor. It is suitable for the environment with low odor requirements.

How to Use No Clean Flux Paste?

‌The basic steps for using no-clean flux are as follows‌:

‌1. Clean the welding part‌: Before using the flux, clean the welding part to ensure that there is no oil, degreaser or moisture on the surface to avoid affecting the welding effect and welding strength‌

‌2. Apply flux‌: After stirring the no-clean flux evenly, apply the flux on the welding part by brushing or dripping, and ensure that the coverage area is sufficient‌

‌3. Welding‌: After waiting for a while, you can perform normal welding. The function of the flux is to improve the welding quality and make the contact surface of the electronic components easy to melt during the welding process.

‌Precautions during use‌:

‌1. Environmental requirements‌: No-clean flux is a flammable chemical material. It should be operated in a well-ventilated environment, away from fire and avoid direct sunlight‌

‌2. Storage and replacement‌: The opened flux should be sealed before storage. Do not pour the used flux back into the original packaging to ensure the cleanliness of the original liquid. The flux should be replaced with new liquid after 50 hours of use to prevent contamination, aging and degradation that affect the work effect and quality.

3. Safe handling: The scrapped flux must be handled by a dedicated person and must not be dumped at will to pollute the environment. If it is accidentally contaminated on your hands and feet, rinse it immediately with soap and water; if it is contaminated on your face, rinse it immediately with soap and water. If the situation is serious, seek medical treatment.

Best Technology engaging in PCB and PCBA assembly industry for more than 18 years. We have professional engineering team to offer one-to-one technical support. And all of our core members have over 10 years experience in PCB industry, we are so confident that we can serve you perfect! Contact us for more!

Tags: no clean flux
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What is Fiducial Marks PCB?

November 13th, 2024

Fiducial marks may seem small, but their impact on PCB manufacturing is substantial. They act as reference points during the assembly process, ensuring precision in placing components. Without them, the accuracy of automated machines would drop, leading to potential misalignment. This guide covers everything you need to know about fiducial marks and their significance in PCB design.

What is the Fiducial Mark?

Fiducial marks are small, round copper pads on a PCB. They serve as reference points to guide automated assembly machines. Usually circular and made of copper, it serves as a visual cue that tells machines where the board is located on the assembly line. In the PCB manufacturing industry, fiducial marks play an important role in improving production efficiency and quality and reducing manual errors.

What is the Purpose of Fiducial Marks?

The fiducial marks on PCB plays a vital role in the manufacturing industry, mainly used to assist equipment or systems in the production process of PCB automatic positioning, alignment error detection, size measurement, lead inspection and other operations. Specifically, the role of fiducial marks includes the following:

Accurate positioning

Fiducial marks can provide high-precision positioning information, so that the PCB components can be accurately aligned and installed.

Automated assembly

Through the use of machine vision system, fiducial marks can be automatically identified and positioned to achieve automated PCB assembly process, improve production efficiency and reduce manual errors.

Quality control

Fiducial marks can be used to detect the position and condition of PCB components for quality control and defect detection to ensure product compliance with specifications.

Accurate calibration

Fiducial marks can be used to calibrate measuring equipment or machine vision systems to ensure their accuracy and stability.

Design update and repair

Fiducial marks can be used as markers or reference points for positioning and adjusting the PCB during design iteration, troubleshooting, and repair.

What are the Different Types of Fiducial Marks in PCB?

Fiducial marks are not one-size-fits-all. Depending on the PCB design and complexity, different types of fiducials come into play:

Global Fiducials: These marks are used to align the entire board. They’re usually placed on the corners or designated locations on the PCB to help machines recognize the board’s overall position.
Local Fiducials: When certain areas of the PCB require high precision—especially spots with tight component layouts—local fiducials come into play. They’re placed near these critical sections to ensure parts like chips and connectors are placed with pinpoint accuracy.
Panel Fiducials: If multiple PCBs are organized into a single panel for manufacturing, panel fiducials are added to align the entire panel. This ensures that each section of the panel stays in place during assembly.

Each type of fiducial has its job, guiding machines from broad alignment down to component-specific positioning.

What is the Size of the Fiducial Marks on a PCB?

The dimensions of the optical points on the PCB are usually circular pads of 1mm to 3mm diameter, plus a solder shield of twice or more the pad size‌. Specifically, the size of the optical points can be adjusted according to different needs, and common sizes include:

1mm diameter round pad ‌ with a 0.6mm radius solder mask.
‌2mm diameter round pad ‌ with a 1mm radius solder mask.

These sizes are chosen to ensure that the optical points can be accurately identified and positioned by the mounter during the SMT production process, especially when dealing with dense pin components, improving the mounting accuracy.

In addition, the shape of the optical point is generally round, because the circular object is easier to be positioned by the machine, and the machine vision system can find the center of the reference point ‌2 more accurately.

What are Fiducial Marks Used For?

Fiducial marks have a straightforward yet essential purpose. They act as guideposts for automated assembly, ensuring the board is positioned and oriented correctly. Their main uses include:

Aligning the Board: Fiducials tell the machines where the board starts and ends, helping them align it for each production step.
Orientation Control: They guide machines to understand how the board is placed on the assembly line, preventing flipped or rotated placement.
Component Precision: Especially with advanced and densely packed PCBs, fiducials ensure that each component is placed where it belongs.

Fiducial Marks vs. Positioning Holes

Fiducial marks and positioning holes are both used for alignment, but they serve different roles. Fiducial marks are visual reference points that automated machines read optically. They tell the machine where the board is and ensure accurate component placement. On the other hand, positioning holes are physical features. They’re used to mount the board securely onto a frame or machine bed, ensuring that it stays put during the assembly or manual handling.

Think of fiducial marks as the eyes of the process and positioning holes as the hands. Fiducial marks guide precision and accuracy, while positioning holes provide stability and physical anchoring.

Tags: fiducial marks pcb
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What are the stack-ups in HDI PCB?

November 11th, 2024

In the field of modern electronic manufacturing, high-density interconnect (HDI) technology has become a key factor driving the development of electronic products towards miniaturization and higher performance. The core of HDI technology lies in its unique stacked design, which not only greatly improves the space utilization of circuit boards, but also significantly enhances electrical performance and signal integrity.

The stacked-up design of HDI PCB allows multiple circuit layers to be connected through precisely controlled blind and buried holes, which have much smaller diameters than traditional PCB through holes. This connect method not only reduces the volume of the circuit board, but also increases the trace density, so that more and more electronic components can be integrated into a limited space.

In addition, the stacked design of HDI also optimizes the path of signal transmission. Due to the shorter signal transmission distance and the avoidance of unnecessary bends and corners, signal delay and loss have been effectively controlled. This is crucial for high-speed electronic devices as they require fast and accurate processing of large amounts of data.

In the manufacturing process, the stacked design of HDI also brings many challenges. In order to achieve high-precision buried/blind hole machining and interlayer registration, manufacturers must adopt advanced laser drilling technology and precision etching equipment. At the same time, in order to ensure the reliability and stability of the circuit board, strictly testing and verification of materials and processes are also required.

So what are the HDI stacking structures? This article will take you into an incredibly wonderful world…

1+N+1 Stack Up

1. Here, “1” (including the following “1”) refers to the layer number of blind holes (Blind via/ micro-via). And one layer blind hole always called a first step.

N refers to the number of non-blind hole layers in the inner layer (not necessarily just the Core), such as 4 layers, combined with 1, which is a 1-4-1 stacked structure. At the same time, if the N-layer is laminated, then this 1-4-1 laminated structure is called first-step-second-lamination (1 times N-layer lamination + 1 times outer layer lamination = 2 times, so it is called second lamination).

Does it make sense? If you have any questions, feel freely to leave a message or contact us at sales@bestpcbs.com.

2. Typical 1+N+1 stack-up

This kind of stack up shown as following is made by laminate a CCL sheet into 4 layers firstly and then laminate into 6 layers. It is also a common product on the market at present.

2+N+2 Stack Up

1. Here, 2 and N have the same meaning as 1-N-1, it will not be repeated again.

2. Typical 2+N+2 stack-up:

There are two types of second-step stack-up: stacked via and staggered via, which have different levels in difficulty, cost, and process.

2.1 Staggered via

Here is a stack-up of a staggered vias, this kind of structure has relatively lower cost and good reliability.

2.2 Stacked via

From the stack-up, it is not difficult to see the difference with staggered vias. This stacking structure requires drilling another blind hole on top of the blind hole, and the previous blind hole needs to be filled with copper or a material that can conduct electricity and resist laser drilling. This gives a rise to another technology, we will introduce in the later HDI electroplating process.

N+N Stack Up

1. Here, the “N” and the “N” in 1-N-1 or 2-N-2 have the same meaning.

2. Typical N+N stack-up

Although N+N stacking may not have blind holes, due to the special process and strict registration requirements, the actual production difficulty is no less than HDI technology.

Anylayer for Any Interconnection

1. The Any-layer means it can conduct at any layer, so how to achieve it?

2. Typical stack-up of Any-layer

From the section of the PCB as following, it can also be seen that how to stack each layer together to form a straight line is also a challenge, so the Anylayer process good or not depends on the registration ability of the manufacturer. Of course, the circuit uses this technology will definitely be very dense and fine, which gives rise to an advanced PCB process called MSAP.

So in summary, despite facing many challenges, HDI’s stacked design has become a key part of high-end electronic products. From smartphones to wearable devices, from high-performance computers to advanced communication systems, HDI technology is playing a crucial role. With the continuous advancement of technology and the increasing demand from consumers, we have reason to believe that HDI’s stacking will continue to lead the innovation trend in the field of electronic manufacturing.

Tags: HDI PCB
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What is 1st Article Inspection?

November 8th, 2024

What is 1st Article Inspection For?

First Article Inspection (FAI) refers to the inspection of the first or several products produced at the beginning of production (such as every day, every shift or the beginning of each production batch) to confirm whether the production conditions (such as equipment, process, materials, environment, etc.) meet the technical and quality requirements. This is a preventive quality control measure designed to prevent batch defects by early detection of possible problems in the production process.

The first inspection usually includes the following steps:

1. Preparation stage: clear inspection standards, inspection methods, inspection tools and equipment, and prepare relevant inspection records and forms.

2. Production preparation: Check whether the production equipment is in good condition, whether the process parameters are set correctly, and whether the raw materials or parts meet the requirements.

3. Production of the first piece: Start production according to the production plan, and make the first piece or the first few products as the first piece.

4. First inspection: Detailed inspection of the first product, including inspection of appearance, size, performance, function, etc., to ensure that the product meets the design requirements and quality standards.

5. Result judgment: According to the inspection results, determine whether the first piece is qualified. If qualified, mass production can continue; If it is not qualified, it is necessary to analyze the cause, adjust the production conditions, and re-make the first part for inspection until it is qualified.

6. Record and feedback: Record the results of the first inspection, and feedback the results to relevant departments and personnel in order to take timely measures to solve the problem.

Why Need to Perform a FAI?

◆ The first inspection in the production process is mainly to prevent the product from a batch of out-of-quality, repair, scrap. It is a means to control the product production process in advance, is an important method of product process quality control. It is an effective and essential method for enterprises to ensure product quality and improve economic efficiency.

◆ The first inspection is to find the factors affecting product quality in the production process as early as possible to prevent bad batch or scrap.

◆ The first piece can be entered into formal production after passing the inspection, mainly to prevent the occurrence of batch unqualified products.

◆ Long-term practical experience has proved that the first inspection system is an effective measure to detect problems as early as possible and prevent products from being scrapped in batches. Through the first piece inspection, it can be found that systematic causes such as severe wear of the fixture or installation positioning errors, poor accuracy of the measuring instrument, incorrect reading of the drawing, feeding or formulation errors exist, so that corrective or improvement measures can be taken to prevent the occurrence of batch nonconforming products.

What Happens if a Component Passes or Fails the FAI?

If a component passes the FAI, full-scale production can proceed to next stage. Because knowing that the process yields parts that match design criteria. Meanwhile, it builds confidence and reduces the likelihood of future issues.

If a component fails, corrective action is necessary. This means process, parameters, or used tools, materials are not suitable or with poor quality. After modifications, a new FAI may be needed to verify the adjustments work as expected.

When Should a First Article Inspection Occur?

Knowing the right time for a 1st article inspection is crucial to avoid production issues and ensure highest quality. But when exactly should this process take place? Let me tell you:

Initial Production Run

Picture this – you’re ready to kick off a new product line or start manufacturing a brand-new part. This is the perfect time for an FAI. Performing it at this stage helps catch any potential problems right from the start. It’s like giving your process a test drive before you commit to full-scale production.

Process Changes

Changes are inevitable in manufacturing. Maybe there’s an upgrade to your equipment or you’re switching up the method used to produce parts. Any significant change to the process means it’s time for a new FAI. Why? Because even small adjustments can lead to unexpected differences in the final product.

Supplier Changes

If you decide to switch to a different supplier for critical components, you shouldn’t skip an FAI. Even if the new supplier promises the same specifications, differences in materials or production methods can impact the final product. An FAI here ensures that what you’re getting from the new supplier matches your quality expectations.

Design Modifications

Tweaking a design might seem minor, but it can change everything from part fit to performance. Any time there’s an update or redesign, running an FAI confirms that the modified product still aligns with the original quality standards.

What is the Difference Between PPAP and First Article Inspection?

You might hear the terms PPAP (Production Part Approval Process) and FAI thrown around in manufacturing discussions. While they share a goal of ensuring quality, they are different in their approach, scope, and where they are commonly used.

1. Industries and Common Use

FAI is used across various industries, and it especially popular in fields like aerospace and defense. It’s typically a requirement when introducing a new part or process. PPAP, on the other hand, is most commonly linked to the automotive industry. It’s a standard method required by major automotive manufacturers to ensure that their suppliers can consistently meet production quality standards.

2. Range and Detail

FAI is about confirming that one specific piece meets all the design and specification requirements. The process involves checking the dimensions, materials, and other key aspects to ensure everything matches up before moving forward with full-scale production.

PPAP, however, takes a broader approach. Instead of just focusing on one component, PPAP is like an in-depth audit of the entire production process. It includes elements like process flow diagrams, control plans, and even failure mode and effects analysis (FMEA). PPAP doesn’t just ask, “Does this part meet the specs?” but goes further to check if the entire production line can consistently produce parts that meet quality requirements over time. A PPAP file like as below:

3. Level of Documentation

FAI has its documentation, but it’s more straightforward. You get a detailed report of the inspected part, including dimensions and results from any tests performed. With PPAP, the documentation is more comprehensive and multi-layered. It often involves around 18 sheets, including a sample production run, process validation reports, and customer-specific requirements.

First Article Inspection in Best Technology

At Best Technology, we believe that FAI is more than a formality—it’s a guarantee of reliability and quality. So, we pay more attention to the first article inspection, from every step, every operator, every report. We have a 1st article inspection tester in our factory, for each prototype, we can finish the FAI inspection quickly and effectively.

As an advanced PCB and PCBA manufacturer, we have more than 18 years experiences in this industry. We have served over 5000 customers with 98% satisfied comments. All of them are amazed with our one-stop service and quick delivery.

Tags: 1st Article Inspection, FAI
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What is hot bar soldering?

November 7th, 2024

Hot bar soldering is a soldering method that uses heat and pressure to connect two or more materials together. The basic principle is to heat the surface of the material to a certain temperature to soften or melt it, and then apply a certain pressure to form a strong bond between the materials.

What is the hot bar process?

Hot bar soldering is a soldering method that applies pressure at a specific temperature. The process involves applying a pressure of 0.5 to 1.5N at a temperature above 200°C, so that the splitter brings the lead into contact with the soldering area and reaches the atomic distance, thereby generating an interatomic force to achieve the purpose of bonding.

Specifically, during hot bar soldering, the temperature is usually above 200°C and the bonding strength is between 0.05 and 0.09N.

Hot bar soldering is widely used in the field of microelectronic surface assembly technology, especially in connecting flexible circuit boards and rigid circuit boards. The stability and efficiency of this process are essential to ensure the good quality of the product.

What temperature is hot bar soldering?

The temperature range of hot bar soldering is usually between 200-400°C below the melting point of the material. Because within this temperature range, the metal surface can melt and fuse together with the help of pressure, forming a high-quality weld.

Hot bar soldering is a method of joining two or more metal materials together by applying heat and pressure at the material joint, causing the material surface to melt and fuse together with the help of pressure.

Temperature is a critical parameter in the hot bar soldering process because it directly affects the quality of the weld and the structure of the metal. If the temperature is too low, the molten pool may not form, resulting in an incomplete connection; while too high a temperature may cause the material to melt excessively and damage the metal structure.

The temperature range of hot bar soldering is affected by many factors, including the properties of the metal, pressure, and welding time. The melting point of the metal is one of the most important parameters affecting the temperature selection, and welding is usually performed below the melting point of the material. Pressure and time also have a direct impact on the welding process because they have a direct impact on the contact and melting of the metal.

In practical applications, choosing the right temperature requires a comprehensive consideration of multiple factors. In the production of multilayer boards, the hot pressing temperature is generally between 150℃ and 180℃, and the specific temperature can be adjusted according to the type of glue used and the characteristics of the board.

In addition, the operating temperature range of high-frequency heat welding machines is generally between 100℃ and 300℃, and some special materials may require higher temperatures, up to 600℃.

What is a hot bar?

Hot pressing welding is a welding method that uses heat energy and pressure to melt and fuse two or more materials together at the contact surface. It is usually carried out at a temperature above 200°C and a certain pressure is applied to make the chopper bring the lead to contact the welding area and reach the atomic distance, thereby generating interatomic forces to achieve the purpose of bonding.

Why use hot air soldering?

The main reasons for using hot air soldering include its high efficiency, energy saving, environmental protection, high strength and wide application range.

High efficiency: hot air welding has a fast speed and can greatly improve production efficiency.

Energy saving: Compared with traditional welding methods, hot air welding consumes less energy and can reduce energy consumption.

Environmental protection: Hot air soldering does not require the use of additional substances such as chemical agents, does not produce harmful substances, has little pollution to the environment, and meets environmental protection requirements.

High strength: The weld of hot air soldering is uniform and strong, and the material after welding is not easy to deform.

Wide range of applications: Hot air soldering is suitable for various metal materials, as well as a variety of plastic materials.

Is hot air soldering better than iron?

Hot air soldering and soldering iron each have their own advantages and disadvantages. The choice of which soldering method depends on the specific application requirements.

Advantages of hot air soldering

High efficiency: The efficiency of hot air soldering is usually higher than that of soldering iron, which is suitable for the removal and welding of large amounts of solder.

Temperature control: Hot air soldering can accurately control the welding process by adjusting the wind force and temperature, and is suitable for handling large-area welding tasks.

High safety: Hot air soldering guns generally use safe voltages and have anti-static functions, reducing the risk of electric shock and static damage to components.

Advantages of soldering irons:

Accurate temperature control: The temperature control of soldering irons is more accurate, which is suitable for occasions that require precise welding, such as the welding of microelectronic components.

Flexible operation: The soldering iron is more flexible to operate and is suitable for delicate soldering work.

Low cost: The initial investment and operating cost of the soldering iron are usually low, which is suitable for users with limited budgets.

Applicable scenarios:

Hot air soldering: Suitable for removing and soldering a large amount of solder, such as circuit board repair and large-area soldering during manufacturing.

Soldering iron: Suitable for occasions that require precise soldering, such as soldering of microelectronic components and delicate circuit board repair.

In summary, hot air soldering and soldering iron have their own advantages and disadvantages, and which method to choose depends on the specific welding needs and application scenarios.

How to use bar solder?

The basic steps for using solder bar are as follows:

Preparation stage: First, put an appropriate amount of solder bar into the tin pot, connect the power supply and turn on the power switch, and adjust the temperature to about 250℃. Use the solder bar to tin the red heating tube until the tin surface covers the heating tube.

Melting process: When the tin bar begins to melt, new solder bar should be added in time until the molten tin surface reaches a suitable height. When there is no solder in the tin melting furnace, do not use the tin melting furnace to heat it.

Temperature control: The set temperature should not be too high to avoid accelerated oxidation of the tin surface. It is generally more appropriate to set it at around 300℃, and the specific temperature can be adjusted according to the use requirements.

Wave soldering process: During the wave soldering process, the content of the solder bar will continue to decrease. When the content is low to a certain extent, new solder bars should be added in time to maintain the height of the solder liquid and reduce the oxidation of the solder bar due to excessive tin wave drop.

Lead solder bar: If lead solder bar is used, it is necessary to remove impure copper and regularly check the solder composition in the soldering furnace.

How does laser soldering work?

Laser welding is an advanced welding method that uses a high-energy-density laser beam as a heat source to locally heat two or more metal or non-metal materials to a molten or partially molten state, and then quickly cools and solidifies to achieve connection.

The working principle of laser welding can be divided into the following steps:

The laser generates a high-power laser beam: The high-power laser beam generated by the laser is focused on the surface of the material to be welded through a lens or other optical elements to form a small spot.

The spot has a strong thermal effect on the surface of the material: The spot has a strong thermal effect on the surface of the material, causing it to quickly heat up to the melting point or boiling point, forming a liquid or gaseous molten pool or vaporization hole.

The laser beam moves along a predetermined trajectory: The laser beam moves along a predetermined trajectory, causing the molten pool or vaporization hole to extend along the direction of the weld. At the same time, due to surface tension and capillary action, adjacent materials flow into the molten pool or vaporization hole to fill the gap.

The molten pool or vaporization hole cools and solidifies rapidly: After the laser beam is removed, the molten pool or vaporization hole cools and solidifies rapidly to form a uniform, dense, and high-strength weld.

In short, hot pressing welding, as an efficient and reliable connection technology, plays an important role in modern industrial production. With the continuous advancement of science and technology, hot pressing welding technology will continue to develop and innovate to provide better connection solutions for the development of various industries.

Tags: hot bar soldering, soldering
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Gold Plated PCB Board: Why Use it?

November 6th, 2024

During the PCB board manufacturing, there is an important process called surface treatment. This is mainly used to protect the board surface from oxidation, corrosion, and good electricity. Gold plating, also is a popular surface finishing method, which commonly used in the industry. As a professional PCB fabricator, here Best Team would like to introduce some key points about gold plating that customers always pay more attention to. Let’s keep reading!

What is Gold Plating in PCB?

Firstly, let’s know what is a gold plating. Gold plating on PCBs refers to a layer of gold applied over specific areas of a circuit board. This gold coating is typically applied on the connectors, pads, and edge contacts of a PCB to improve electrical conductivity and provide better resistance against wear and oxidation. Gold plating protects these sensitive areas, which are critical for the performance and reliability of the PCB.

The principle of gold plating is to dissolve nickel and gold (commonly known as gold salt) in the chemical solution. And then the circuit board is immersed in the electroplating cylinder and the current is passed on the copper foil surface of the circuit board to generate nickel gold coating. Due to the electric nickel gold has good hardness, wear resistance, and not easy to oxidization, it is widely used in the electronics.

Does Gold Plating Process Use Real Gold?

‌The gold plating in PCB is not really pure gold, but a gold alloy (has gold and some other metals in it). ‌

In PCB manufacturing, gold-plating is usually not done using pure gold, but by compression and treatment of gold alloys. Such alloys often contain small amounts of metals such as silver, nickel, and copper to reduce costs and meet specific performance requirements.

The role of gold plating in PCB is mainly to enhance electrical conductivity and chemical stability. Gold has good electrical conductivity and oxidation resistance, which can provide stable signal transmission and reliable connections in electronic devices. In addition, gold does not discolor or corrode, making it an ideal material for electronic applications.

In general, there are two main gold-plating processes: electrolytic gold-plating and brush gold-plating. Electrolytic gold plating is the deposition of metal on the circuit board through chemical bath and electrolytic process, which has higher cost but better quality. Brush gold plating, by depositing metal particles onto a conductive substrate via electronic devices, is cheaper but of poorer quality.

Why Use Gold in PCB?

May somebody curious about why use gold in PCB? To make the PCB surface more beautiful? Let me tell you why.

1. Improve electrical conductivity

Metals such as gold have good electrical conductivity. Through gold plating, a metal conductive layer can be formed at the circuit connection of the PCB board, thus significantly improving the electrical conductivity of the circuit. This helps to reduce the resistance at the circuit connection, reduce signal loss.

2. Prevent oxidation and corrosion

The gold coating has excellent chemical stability and can resist oxidation and corrosion. This can protect the PCB board from the erosion of harmful substances in the external environment, such as humidity, salt spray, chemical gases, etc., thereby extending its service life.

3. Improve welding performance

Oxidized layer may be formed on the metal surface during welding, affecting welding quality. The gold coating can reduce the thickness of the surface oxide layer, thereby improving the reliability and robustness of the welding. In addition, gold plating can also provide better welding contact, reduce thermal stress during welding, and reduce the occurrence of welding defects.

4. Enhance the appearance

Gold plating can give the PCB surface metallic luster, improve the appearance texture and product grade, and increase the market competitiveness of the product. To be honest, gold appearance indeed gives a better appearance.

5. Meet specific needs

In some high-end electronic products, there are higher requirements for the electrical conductivity, corrosion resistance, welding performance and appearance texture of PCB boards. Gold plating, as an effective surface treatment technology, can meet these specific needs.

6. Meet welding quality challenges

With the improvement of integration of electronic products, IC feet are becoming more and more dense, and traditional vertical tin injection technology is difficult to meet the welding challenges of thin pads. Gold plating technology can provide better welding performance and reliability, and reduce the occurrence of welding quality problems such as virtual welding.

How Thick is Gold Plating on Circuit Boards?

The thickness of gold plating on PCBs depends on the type and application. Generally, PCB gold plating thickness ranges from 0.1-1.27um. For standard PCBs, a gold layer thickness of 0.03 to 0.05 microns is common, especially for immersion gold. However, thicker plating is applied for connectors or contacts exposed to frequent wear and tear, as these areas need more protection.

Hard gold, used for high-wear applications like edge connectors, typically has a greater thickness than immersion gold. The thickness is carefully controlled because too thin a layer might fail to provide effective protection, while an excessively thick layer could lead to wasted materials and unnecessary expense. The goal is to strike a balance that delivers durability without incurring excessive costs.

What is the Difference Between Immersion Gold and Hard Gold PCB?

Hard gold plating ‌is by electroplating, so that the gold particles are attached to the ‌PCB board, so it is also called electric gold. Because of its strong adhesion, hard gold plating is also called hard gold, which is often used for ‌ memory bar ‌ gold finger and other parts that need wear-resistant.

‌Immersion gold ‌ is through the ‌ chemical reaction, the gold particles crystallization and attached to the PCB ‌ pad, so it is also known as ‌ soft gold. Due to the weak adhesion, the sinking gold is mainly used for the surface treatment of the pad, and the weldability is good. The difference between hard gold plating and immersion gold are including:

Color: Immersion gold is more yellow, while gold plating is more white.
Crystal structure: Immersion gold has a denser crystal structure.
Thickness: Immersion gold has a thicker layer of gold.
Wear resistance: Gold plating is harder and more resistant to wear and tear.
Solderability: Immersion gold is easier to solder.
Short circuits: Gold plating is more likely to cause short circuits.
Oxidation resistance: Immersion gold is less prone to oxidation.
Cost: Immersion gold is more expensive.
Deposition process: Gold plating uses an external electric current, while immersion gold is a chemical process.
Suitability: Gold plating is better for environments with high mechanical stress, while immersion gold is better for movable contacts.

PCB Applications of Gold Plating

Gold-plated PCBs are popular in industries where reliability and durability are essential. Some typical applications include:

Aerospace and Defense
Medical Devices
Telecommunications
Consumer Electronics
High power electronics
High current electronics
Low voltage digital logic electronics

As a PCB and PCBA manufacturer, we provide various surface treatment options for customers, including: ENIG, ENEPIG, OSP, HASL-LF, Immersion gold, hard gold (up to 50u’’). We offer customized PCB service tailored to customer’s requirements, we will try our best to meet the demands of surface treatment. Welcome to contact us if you have any questions.

Tags: gold plated pcb board
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What is a PCB antenna? How does it work?

November 5th, 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?

November 4th, 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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