Archive for the ‘FR4 PCB’ Category

What You Know About Counterbores in PCB Design and Manufacturing

Friday, August 18th, 2023

In the world of design and manufacturing, precision is paramount. Every detail, down to the placement of a single component, can impact the performance and appearance of a product. This is where the concept of counterbores comes into play, a technique employed in various industries to create recessed areas for components or fasteners.

But firstly, what is counterbore? Today we will show you the definition and applications of the countersink in a PCB design.

Definition and Applications:

A counterbore is a cylindrical, flat-bottomed hole that is strategically cut into a material to accommodate specific components or fasteners. It is commonly used in various industries, including woodworking, metalworking, and mechanical engineering. The purpose of a counterbore is to create a recessed area where a component, such as a bolt head, nut, or other hardware, can sit flush with or below the surface of the material. This technique ensures a smooth appearance, prevents interference with other components, and provides mechanical stability.

Counterbores in PCB Design and Manufacturing

In the realm of printed circuit boards (PCBs), counterbores play a crucial role in achieving efficient and functional designs. PCBs are essential components in electronic devices, and their design requires careful consideration of component placement, connectivity, and mechanical stability. Counterbores in PCBs serve several important functions:

Component Alignment and Clearance: Certain components on a PCB, such as connectors, switches, or specialized modules, require precise alignment and clearance for optimal functionality. A counterbore can be introduced to create a recessed area that accommodates these components, ensuring proper alignment with neighboring components and minimizing the risk of interference.

Flush Mounting: To maintain a sleek and compact design, some components need to be mounted flush with the surface of the PCB. A counterbore creates a flat-bottomed recess that allows the component to sit at the same level as the PCB surface, contributing to an aesthetically pleasing and functional layout.

Mechanical Support: Components that are susceptible to mechanical stress or impact may benefit from additional support. By incorporating a counterbore, the PCB design can provide a more secure location for these components, reducing the risk of damage.

Heat Dissipation Enhancement: In applications where certain components generate significant heat, such as power amplifiers or processors, heat sinks are often employed to dissipate the heat. A counterbore can facilitate proper alignment and contact between the heat sink and the component, optimizing heat transfer and overall thermal performance.

The production of counterbores in PCBs involves specialized manufacturing techniques. BEST Technology as a professional PCB manufacturer, we will use precision drilling and routing equipment to create accurately sized and positioned counterbores.

If you want to know more about the counterbores, welcome to follow our post or contact us.

Common Types of Holes in PCB

Upon examining a circuit board, one will discover an array of holes serving specific purposes. These include Via holes, PTH, NPTH, Blind holes, Buried holes, Counterbore holes, Countersunk holes, Location holes, and Fiducial holes. Each hole type fulfills a distinct role and function within the PCB, making it crucial to familiarize oneself with their characteristics to facilitate optimal PCB design.

1. Via holes

Via holes are small openings that connect different layers of a printed circuit board (PCB). They facilitate the seamless flow of signals and power between the layers, enabling efficient circuit design and transmission. Vias can be classified into two types: Plated Through-Holes (PTH) and Non-Plated Through-Holes (NPTH), each serving different functions.

2. PTH (Plated Through-Hole)

Plated Through-Holes (PTH) are vias with conductive material coating the inner walls. PTHs establish electrical connections between different layers of a PCB, allowing the passage of signals and power. They play a crucial role in interconnecting components, facilitating the flow of electrical current, and ensuring the functionality of the circuit.

3. NPTH (Non-Plated Through-Hole)

Non-Plated Through-Holes (NPTH) lack the conductive coating on their inner walls, making them suitable for mechanical purposes only. These holes are used for mechanical support, alignment, or as positioning guides, without establishing any electrical connections. NPTHs provide stability and precision, ensuring proper alignment of components within the circuit board. The mainly different between PTH and NPTH is the copper foil will be plated in the hole wall while NPTH no need to do plate.

4. Blind Holes

Blind holes are partially drilled holes that penetrate only one side of a circuit board. They are primarily employed to connect the outer layer of the board with the inner layer, enabling component mounting on one side while remaining hidden from the other. Blind holes offer versatility and help maximize space in complex circuit board designs.

5. Buried Holes

Buried holes are entirely enclosed within a circuit board, connecting inner layers without extending to the outer layers. These holes are hidden from both sides of the board and serve to establish connections and routes between inner layers. Buried holes allow for denser circuit board designs, reducing the complexity of routing traces and enhancing the overall functionality of the board. They provide a seamless and compact solution without any surface exposure.

6. Counterbore Holes

Counterbore holes are cylindrical recesses created to accommodate the heads of bolts, nuts, or screws. They provide a flat-bottomed cavity that allows the fasteners to sit flush or slightly below the surface of the material. The primary function of counterbore holes is to enhance the aesthetics and functionality of a design by providing a smooth and even appearance. These holes are commonly found in woodworking, metalworking, and engineering applications where a concealed or larger bearing surface is desired.

7. Countersunk Holes

Countersunk holes are conical recesses designed to house the angled heads of screws or fasteners. They are employed to ensure that the screw heads lie flush or slightly below the material surface. Countersunk holes serve both aesthetic and practical purposes, providing a sleek and flawless finish while reducing the risk of snags or protrusions. Their versatility makes them suitable for various applications, from furniture manufacturing to aerospace engineering.

8. Location Holes

Location Holes, also known as Reference Holes or Tooling Holes, serve as key reference points for aligning and positioning components, parts, or fixtures during manufacturing or assembly processes. These holes are strategically placed in a design to ensure precise and consistent alignment, enabling efficient assembly and reducing errors.

9. Fiducial Holes

Fiducial Holes, also referred to as Fiducial Marks or Alignment Marks, are small precision holes or markings placed on a surface or PCB (Printed Circuit Board). These holes serve as visual reference points for vision systems, automated processes, or machine vision cameras.

As we conclude our journey through the fascinating world of holes in engineering, we have gained a deeper understanding of the functions and positions of counterbore holes, countersunk holes, via holes, PTH, NPTH, blind holes, and buried holes. These holes are essential elements in various industries, contributing to the aesthetics, functionality, and efficiency of designs.

After introducing each of them, you should have gained a deeper understanding of their functions, hope this is helpful for you the design holes on your PCB project!!

What is BGA Soldering?

BGA soldering is a technique that involves the attachment of integrated circuit packages to a PCB using an array of solder balls. These solder balls are typically made of lead-based or lead-free alloys, depending on environmental regulations and specific requirements. The BGA package consists of a substrate, which acts as a carrier for the integrated circuit, and the solder balls that form the electrical and mechanical connections between the package and the PCB.

The Importance of BGA Soldering in Electronics Manufacturing

BGA soldering plays a critical role in the manufacturing of various electronic devices such as computers, smartphones, and gaming consoles. The increased demand for smaller and more powerful electronics has driven the adoption of BGA packages. Their compact size and high pin density make them suitable for advanced applications where space is limited.

Challenges Faced in BGA Soldering

Component Alignment and Placement

One of the primary challenges in BGA soldering is ensuring accurate component alignment and placement on the PCB. The small size of the solder balls and the dense layout of the BGA package make it difficult to achieve precise positioning. Misalignment during the assembly process can result in solder bridges, open connections, or mechanical stress on the package.

To address this challenge, manufacturers employ advanced technologies such as Automated Optical Inspection (AOI) and X-ray Inspection. AOI systems use cameras and image processing algorithms to verify the correct alignment and placement of BGA components. X-ray inspection, on the other hand, allows manufacturers to see beneath the surface of the PCB and detect any misalignment or defects that may not be visible to the naked eye.

Solder Paste Application

Another significant challenge in BGA soldering is achieving precise and consistent solder paste application. Solder paste, a mixture of solder alloy and flux, is applied to the PCB pads before placing the BGA package. Inadequate or excessive solder paste can lead to solder defects such as insufficient solder joints, solder voids, or solder bridging.

To overcome this challenge, careful attention must be given to stencil design and aperture selection. Stencils with appropriate thickness and properly sized apertures ensure accurate solder paste deposition. Additionally, manufacturers can employ Solder Paste Inspection (SPI) systems to verify the quality and consistency of the solder paste applied. The solder paste that Best Technology uses is SAC305 solder paste, which has good printability and excellent stability.

Temperature Profiling

Temperature profiling, or we can say the thermal management, it is crucial in BGA soldering to ensure proper reflow of the solder paste. The reflow process involves subjecting the PCB to a carefully controlled temperature profile, allowing the solder paste to melt, form a reliable joint, and solidify. Inadequate temperature profiling can lead to insufficient solder wetting, incomplete reflow, or thermal damage to components.

Manufacturers must optimize the reflow oven setup and calibration to achieve the correct temperature profile. Thermal profiling techniques, such as the use of thermocouples and data loggers, help monitor and control the temperature during the reflow process.

Reflow Process

The reflow process itself presents challenges in BGA soldering. The soak zone, ramp rates, and peak temperature must be carefully controlled to prevent thermal stress on the components and ensure proper solder reflow. Inadequate temperature control or improper ramp rates can result in solder defects such as tombstoning, component warpage, or voids in the solder joints.

Manufacturers need to consider the specific requirements of the BGA package and follow recommended reflow profiles provided by component suppliers. Proper cooling after reflow is also essential to prevent thermal shock and ensure the stability of the solder joints.

Inspection and Quality Control

Inspection and quality control are critical aspects of BGA soldering to ensure the reliability and performance of the solder joints. Automated Optical Inspection (AOI) systems and X-ray inspection are commonly used to detect defects such as misalignment, insufficient solder wetting, solder bridging, or voids in the solder joints.

In addition to visual inspection techniques, some manufacturers may perform cross-section analysis, where a sample solder joint is cut and examined under a microscope. This analysis provides valuable information about the quality of the solder joint, such as solder wetting, void formation, or the presence of intermetallic compounds.

In a word, BGA soldering presents unique challenges in electronics manufacturing, primarily related to various factors. By addressing these challenges effectively, manufacturers can ensure the reliability and performance of BGA solder joints, contributing to the production of high-quality electronic devices. Best Technology has rich experience in PCBA assembly and we mounted thousands PCBs for our customers, whatever it is simple design or complex design, all the products are assemble perfect and work well in customer side. Please feel free to contact us for any questions about PCBA.

What is metal core PCB?

A Metal Core PCB (MCPCB), also known as a thermal PCB or metal backed PCB, is a type of PCB that a metal material as its base for the heating dissipation part of the board. The thick metal is covering one side or double side of the PCB. The purpose of the core of a MCPCB is to redirect heat away from critical board components (such as LED or IC chips), and to less crucial areas such as the metal heatsink backing or metallic core. Base metals in the MCPCB are used as an alternative material to FR4 boards.

Same as FR4 PCB, the metal core PCB can be divided into Single layer MCPCB, Double layers MCPCB and Multi-layer MCPCB.

Single layer MCPCB

A single layer MCPCB is consist of a metal base (usually aluminum or copper alloy), thermal conductivity/dielectric layer and a copper trace layer, you can check below stack up for more details. Due to it only has one layer copper trace, sometimes we called it as one-layer MCPCB or single sided MCPCB.

The single sided MCPCB can be used with surface mount and chip & wire components, and provides much lower thermal resistance than FR4 PCB. What’s more, the metal core provides lower cost than ceramic substrates, and allows much larger areas than ceramic substrates.

Meanwhile, superior heat dissipation and good durability of Aluminum of metal core PCB can greatly eliminate heat sinks or other some voluminous hardware for engineers or designers.

Double layer MCPCB

Double layers MCPCB (2L MCPCB) has two copper layers on one side of PCB, and metal core as a base core on the bottom side of whole MCPCB, so the components only can be populated on the top side, below is a structure of double layer MCPCB.

(Stack_up_of_double_layers_metal_core_PCB)

From the stack up of double layers MCPCB, we can see it consists of a single layer MCPCB and a double sided FR4 PCB, so it needs an additional pressing process to laminate the thermal conductivity and FR4 PCB. Compared with normal FR4, this structure needs more technology and experience on laminating of two layers together with metal core.

There are two layers copper trace on the surface of MCPCB, can we call it as double sided MCPCB like single layer MCPCB?

The answer is NO, because they have different structure and perform different properties. In our next post, we will show you the differences between double sided MCPCB and 2 layers MCPCB.

Multi-layer MCPCB

Same as FR4 PCB, for those copper traces more than 2 layers, we named them Multi-layer MCPCB. Its structure is same as FR4 PCB, but more complex to fabricate. Below is a typical stack up of a 4 layers MCPCB:

Contrast with single layer or double layers MCPCB, multi-layer MCPCB can populate more components and achieve better performance in electronical performance.

Why Choose Metal core PCB?

Metal core PCB offers a great list of advantages when apply in a high-power application, below we listing some benefits of it:

Excellent heat dissipation
Lower thermal expansion than FR4 PCB
Dimensional stability than polyimide FPC
Great durability
Long lifetime
High utilization rate of space due to the heating can be transferred quickly
High strength and lightweight than FR4 PCB
Cost-effective

Where can we use Metal core PCB?

Metal core PCB can be used in high-power filed where requires fast cooling, good heat dissipation characteristics, the following popular applications may give you a guideline:

LED lighting
Power suppliers
Power conversion system
Automotive electronics
Telecom industrial
Photovoltaics
Semiconductors

With more than 16 years manufacturing experience, Best Technology is one of MCPCB supply leaders in Asia with good metal core PCB capability, we are so confident that we can provide you high quality, fast delivery and excellent one-stop service. Warm welcome to contact us if you have inquiries.

HASL Surface Finish

HASL (Hot Air Solder Level) can be known as tin-lead HASL and lead-free HASL, it was the mainstream surface treatment technology in the 1980s, but with the increased of “small and high density” demands in PCB, there are less and less circuit boards use the HASL technology because it will cause the defective products due to the solder point are easy to leave on the board surface during SMT process. In view of this situation, some PCB board manufacturers or designers prefer use OSP or immersion gold to ensure the good quality products as well as smooth production process.

Tin-lead HASL

Advantages:

1） Economical and widely available.

2） Excellent solderability.

3）Better mechanical strength & lustrousness than lead-free HSAL.

Disadvantages: it is harmful to environment and violates RoHS compliance.

Lead-free HASL

Advantages: low cost, good solder performance and environmental.

Disadvantages: mechanical strength & lustrousness are not good than lead HASL.

In additional, due to the poor surface flatness of HASL circuit boards, neither leaded nor lead-free HASL is not suitable for soldering fine-pitch components or plated through-holes, because it will cause the short circuits and poor welding during the assembly process.

OSP

OSP (Organic Solderability Preservatives) also named as pre flux, the working principle is to generate a layer of organic film chemically on the copper surface to protect the surface from oxidation or vulcanization in the room environment. Meanwhile, OSP also can increase the oxidation resistance, heat shock resistance and moisture resistance of a PCB.

OSP is equivalent to an anti-oxidation treatment, the protective thin film can be easily removed by the flux quickly under the high soldering temperature, then it makes the exposed copper surface immediately combined with the molten solder in a very short time to become a solid solder spot.

At present, the usage of OSP surface finishing process has increased significantly because it is appropriated for both low and high-end products. If your application has no surface connection functional requirements or storage life limitations, the OSP process is the most desirable surface treatment process.

Advantage:

1）With all the advantages of bare copper soldering, expired (more than 3 months) boards can also be resurfaced, but one time is better.

2）Good for fine-pitch, BGA and smaller components.

3）Low cost and easy to rework.

4）Simple process and easy to ensure quality.

Disadvantage:

1）OSP is easily affected by acid and humidity, so must be packed with vacuum.

2）Need to do surface treatment again if storage time more than 3 months.

3）It should be used within 24 hours after unpacking.

4）OSP is an insulating layer, so the test point must be printed with solder paste to remove the original OSP layer for electrical testing.

ENIG

ENIG (Electroless Nickel/Immersion Gold) is one of a chemical nickel gold deposition method, the working principle is to generate a layer of coating by chemical REDOX reaction to get a thicker gold layer. Currently, ENIG is mainly used in the surface of the circuit board with connection functional requirements and long storage life.

Advantage:

1）Can be stored long time as well as no oxidation.

2）Good flatness surface and suitable for small solder point components.

3）Good solderability.

4）Can be used as the base material for COB wire bonding.

Disadvantage:

1）High cost than other two surface treatments.

2）Easy to exist black-pad issue during production process.

As we can know from above information, each PCB surface treatment has its own merit and demerit, you can choose the one according to the effect you want to reach, as well as your cost.

If you don’t know which is best for you, you can send inquiry to us, our professional engineering team and PCB sales will choose the suitable one for you. Welcome to contact us if you have any other questions.