4 Tips of PCB Board Inspection

PCB board inspection is a process that involves various tests to find defects. This process involves checking the board for roughness, warpage, and dimensioning. It also involves inspecting the board’s surface quality for defects such as pits, scratches, and voids. In addition, it requires thorough inspection of electrical connectors, vias, and pad plating for defects.

Automated optical inspection (AOI)

AOI is an excellent tool for evaluating the quality of a PCB board. This process can help detect defects in a PCB before they lead to other problems. AOI uses an image processing system to recognize defects. It can also gauge the package’s dimensions. It consists of several parts, including an actuating system, an illumination system, and a CCD image system.

AOI can be used at any stage in the fabrication process, including during reflow soldering, a critical stage of the production process. It is ideal for high volume production because it is capable of detecting multiple defects. However, it is not recommended for low-volume production or development runs. Moreover, it requires considerable investment and time to set up. AOI can help you reduce costs while increasing efficiency by modifying manufacturing parameters.

AOI is very useful for detecting solder bridges. It also detects excess solder on pads. This is a problem that can be missed by human inspectors, especially if they have to examine dozens of boards of similar design. AOI can detect these defects and send the board for rework if necessary.

Electrical tests

Electrical tests for pcb board inspection involve testing a circuit board’s traces. These tests can help determine if there are any faults or design issues. They can also help determine if a circuit board has sufficient isolation between components. There are various types of tests available, each focusing on a different area of the board.

Electrical tests are often used to confirm that a circuit board is free from shorts and other problems. This is usually done by pushing a board against a bed of probes. The testing process is time-consuming and requires expensive tooling. There are several different types of circuit board inspection machines, and each has its own pros and cons.

A second type of test involves analyzing the board’s structure. This is also called cross-section analysis. This is a destructive procedure, but it reveals critical design defects. This type of test is often required for complex and high-volume PCB production.

X-rays

PCB board inspection with X-rays can be a highly accurate process. The high-penetration power of x-rays results in high-quality images that reveal differences in density and thickness of PCBs. This data can be used to determine the quality of a joint or to diagnose a fault in a design. This technology is used in many industrial processes, from the initial manufacturing stage to final testing.

By looking through a PCB board with X-rays, inspectors can detect problems that are hidden in the board’s surface. In addition to identifying voids, bridges, and other ‘hidden’ connections, X-rays can detect buried or blind vias, as well as excessive or insufficient solder paste. X-rays are also useful for inspecting ‘Ball grid array’ surface-mount packaging, a common type of PCB board. In this type of PCB, there are more connections on the board than on standard PCBs, and it’s harder to examine them with visual inspection alone.

PCB X-ray inspection can provide high-quality measurements and help manufacturers ensure the quality of their PCBs. X-rays are ideal for two or multi-layer boards because they can test the inside of the sample. They can also detect defects that other methods can’t detect, and a high test range allows for more accurate results. X-rays can also provide measurement information, which can be used to evaluate the production process.

Tomography

PCBs can be inspected using X-ray technology. This advanced technique uses a special fixture to hold the PCB in place as it is exposed to x-rays. The fixture helps engineers view the subject from different angles. The detector measures the amount of attenuation at each projection, which is then used to reconstruct the object. PCBs are made of a variety of materials, and some materials absorb more X-rays than others.

Using tomography to examine PCB boards has several advantages. It can accurately identify any missing or incorrectly positioned pins or connectors. It is also able to detect any internal defects in IC chips. Furthermore, it can measure the soldering quality of ball grid arrays.

PCBs can also contain invisible defects. X-ray images can identify missing or cracked solder joints. The images collected by these machines are highly detailed and allow inspectors to analyze various aspects of the defect. A void in a board’s solder joints will reduce the heat conductivity of a solder joint and decrease reliability.

The Most Common PCB Defects and Its Solutions

There are many problems with PCBs, but some of them are less obvious than others. These problems are called implementation failures and require specialized knowledge to diagnose. For example, Electrostatic discharge, Chemical leakage, Lifted pads, and component shifting are all possible causes of failure. To identify the failure modes, a PCB must be stress tested until it fails.

Electrostatic discharge

Electrostatic discharge (ESD) is a common problem in electronic circuits. It results from the wrong handling of electronic components or an excessive voltage level. In many cases, the resulting damage is latent or catastrophic. This problem can cause a PCB to malfunction partially or completely.

There are several ways to detect and repair electrostatic discharge. While some of these are visible and will affect the performance of the product, others will not. The first method is to inspect the device to determine if any component is affected. In some cases, a minuscule hole will appear on the circuit board.

Chemical leakage

Chemical leakage in PCBs can be a problem for many industries. Although the United States banned the production of PCBs in 1977, they are still found in the environment at very low levels. Environmental cycling is the primary source of ambient PCBs, and they are transported throughout ecosystems. Although these contaminants have low levels, they can have serious effects on humans and the environment.

In addition to their use in electronics, PCBs were also used in the construction of school buildings during the 1950s to 1970s. Many schools had PCB-containing caulk and fluorescent light fixtures. The problem with these products was that they leaked, causing contamination in other building materials and the soil. This caused widespread contamination, which is why they were banned.

Lifted pads

Lifted pads are caused by a number of causes, including excess heat and force during soldering. The result can be an unsatisfactory solder joint. These defects require re-soldering, and can lead to short circuit hazards. Other causes of lifted pads include pollutant contamination, poor cleaning, or insufficient flux. Lifted pads can affect the functioning of circuits and the appearance of the board.

Lifted pads occur most frequently on thin copper layers and boards that lack through-plating. Identifying the root cause of a lift is crucial for preventing further damage. In the case of single-sided circuit boards, the problem is often the result of improper wave soldering. The lift can be prevented by using extreme caution while handling PCBs and avoiding excessive force when handling components.

Component shifting

Component shifting is one of the most common defects encountered in PCB assembly. It can be caused by a number of factors, including the placement of components incorrectly. For example, a component placed in a way that is not oriented correctly may float, resulting in a realignment of the component.

In some cases, the cause of component shifting is due to mismatching of the parts to the pad geometry. This causes the component to move towards the thermal mass closest to it. Other causes include bent leads, improperly placed components, or oxidation. Fortunately, there are a number of solutions to component shifting. For instance, adhering to the correct reflow profile, reducing movement during the unreflowed assembly process, and using an aggressive flux can all help minimize component movement.

Soldering ball defects

Soldering ball defects are common in the SMT assembly process. They are essentially balls of solder that separate from the main body of the solder. To prevent them, you should adjust the mounting pressure on the chip mounter to a precise setting. This will prevent the solder paste from being squeezed out of the pad and increase the chance that the solder paste will be generated properly.

A good solder joint will be clean, symmetrical, and have a concave shape. On the other hand, a bad solder joint may be large and have a long stem. Another common defect is disturbed joints, which will have a flaky, distorted, or uneven appearance.

Thermal imaging

Thermal imaging is a powerful tool for quality control, speeding up PCB and component repairs. By identifying hot spots, thermal images can point out faulty components or areas that are using too much power. This information can help designers reduce power consumption and prolong battery life. Thermal imaging can also detect areas that have poor thermal management, requiring more cooling, larger heat sinks, or even redesign.

Thermal imaging for PCB defects can also help designers and engineers determine the cause of defects. When a test board fails to pass quality control tests, a thermal imager can reveal the problems. It can also show the differences in temperature between two different areas of a board, revealing how the two differ.

How High Thermal Conductivity PCB Material Will Solve the Heat Dissipation Problem

PCBs, also known as printed circuit boards, are layered structures made of copper foils sandwiched between glass-epoxy layers. These layers serve as a mechanical and electrical support for components. The high-conductivity copper foils serve as the conductive circuit in the PCB, while the glass-epoxy layer serves as the non-conductive substrate.

High thermal conductivity pcb material

Thermal conductivity is the ability of a material to transfer heat away from a device. The lower the thermal conductivity, the less efficient the device is. High thermal conductivity materials can eliminate the need for vias and produce a more uniform temperature distribution. This also reduces the risk of localized volumetric expansion, which can lead to hotspots near high-current components.

A typical PCB for a personal computer might consist of two copper planes and two outer trace layers. Its thickness is about 70 um and its thermal conductivity is 17.4 W/mK. The result is that the typical PCB is not an efficient heat conductor.

Copper coins

Copper coins are small pieces of copper embedded into the PCB. They are placed under the component that produces the most heat. Their high thermal conductivity allows them to transfer heat away from the hot component to a heat sink. They can be made in different shapes and sizes to fit the desired areas and can be metalized to ensure a tight connection.

Glass-epoxy

The problem of heat dissipation is becoming more important in electronics. Excess heat can lead to underperformance and early failure. Currently, heat dissipation options are limited, particularly in the extreme environments. One of the solutions to this problem is the use of high-temperature glass epoxy PCB material, or HDI-PCB. This material is able to solve this problem by having a thermal conductivity over two hundred times better than FR4 composite.

The glass epoxy resin has excellent heat and flame resistance. It has a high glass transition temperature and high thermal conductivity. It can serve as an insulating layer and a heat dissipation layer. It can be made by impregnation or coating. The thermal conductivity of glass epoxy PCB will improve the performance and stability of electronic components.

Metal core PCBs

Metal core PCB manufacturers have introduced new board substrates that can withstand high temperatures. This allows them to selectively apply thicker copper layers that have higher thermal conductivity. This type of PCB enables better heat dissipation and can be used for fine circuit patterns and high-density chip packaging.

In addition to offering higher thermal conductivity, metal PCBs are also dimensionally stable. Aluminum metal core PCBs have a 2.5-3% size change when heated, making them ideal for high-power applications. Their low thermal expansion properties also make them suitable for high switching power. The most commonly used metal used for a metal core PCB is aluminum, which is cheap and recyclable. Its high thermal conductivity allows for a fast cooling process.

Another problem associated with heat dissipation is the risk of excessive heat. The heat generated by heat-generating components must be removed from the board, otherwise the PCB will not perform at its best. Fortunately, there are now new options to solve this problem. High thermal conductivity metal core PCBs are a new kind of thermal solution that can overcome these problems.

FR4 substrates

PCBs are layered structures made of copper foils and glass-reinforced polymers. They support and connect electronic components. The copper creates a conductive circuit within the PCB, while the glass-epoxy layer acts as a nonconductive substrate.

High-power components are best placed near the center of the PCB, rather than on the edges. This is because heat accumulates near the edges and scatters out. Also, heat from high-power components should be placed far away from sensitive devices, and the heat must be channeled away through the PCB.

High thermal conductivity PCB material is the best solution for heat dissipation, allowing for rapid transfer of heat and preventing heat accumulation. High-tech PCBs use copper base, aluminum, or ceramic as the substrate material. This will solve the heat dissipation issues and make the PCBs more durable.

Things to Know Before Ordering a PCB Project

If you are going to order a PCB project, there are a few things that you should be aware of. For instance, you must double check your traces before ordering. In addition, you need to make sure that your BOM and drill file match. Moreover, you must choose the right material.

Double checking traces

When ordering PCBs from a PCB manufacturer, it is crucial to double-check the traces and spacing on your board. The thickness and width of the traces on your project will determine the amount of current that can flow through the circuit. You can use an online trace width calculator to find the ideal trace width. This will reduce the chances of connections breaking.

Checking your BOM

The first step in ordering PCB components is checking your BOM. It will help you avoid missing or incorrect component numbers. Using the BOM is also beneficial when it comes to sourcing parts. The description of the component will help the buyer and assembly house find a suitable replacement part. This will also help them confirm that the parts have the right MPN.

It is important to check your BOM before sending the PCB project to a manufacturer. This is because even a small mistake can cause problems during the PCB assembly process. You should also keep track of any changes made to the BOM and label them clearly. The most up-to-date version of the BOM is the one that you should use.

Once you have your BOM, you need to find out the cost of the component you’re ordering. It is important to know exactly what you’re going to be paying. The price of your components should match the BOM of your PCB project. If not, you may have to replace the components or even change the design.

Checking your drill file

You can easily check your drill file before ordering your PCB project from a PCB manufacturing company. However, there are some important things you must remember before placing an order. The first step is to make sure that the file is in the correct format. You can use a gerber file viewer to double check your file.

A drill file is a secondary file that explains where holes should be drilled on the PCB. This file must be sent along with the Gerber files. If your Drill file does not specify the locations or sizes of holes, your PCB order will fail the audit.

The drill file should also contain a tool list. It lists which tools are needed for each component hole. The tool list should be either embedded in the drill file or be sent as a separate text file. Failure to provide this tool list on the fabrication drawing will eliminate automated verifications and result in more errors when it comes to data entry.

Choosing the right materials

Choosing the right materials for your PCB project is essential. The physical properties of PCB materials can significantly affect the performance of the board. For example, a lower dielectric constant will mean thinner dielectrics and lower board thickness, while a higher dielectric constant will lead to higher losses. This information will help you narrow down your selection of PCB materials and find those that deliver the required performance.

Next, you should determine the number of routing layers on your PCB. For a simple PCB design, there may be only one or two layers, while a moderately complex design may need four to six layers. More complicated designs may require eight layers or more. The number of layers will directly affect the cost of your PCB project.

How to Know the Surface Finish From PCB Color

If you’re wondering how to know the surface finish of a PCB, you’re not alone. The color of a PCB can reveal its surface finish. You may also see a color designation called ENIG or Hard gold, Silver, or Light red. Regardless of what you see, you’ll want to make sure the PCB is plated to protect the surface.

ENIG

ENIG surface finish is one of the most popular finishes for PCBs. It is made by combining gold and nickel. The gold helps protect the nickel layer from oxidation, and nickel acts as a diffusion barrier. The gold layer has a low contact resistance and is usually a thin layer. The thickness of the gold layer should be consistent with the requirements of the circuit board. This surface finish helps extend the life of the circuit board. It also has excellent electrical performance and enhances electrical conduction between the PCB’s components.

ENIG surface finish has a higher cost but a high success rate. It is resistant to multiple thermal cycles and displays good solderability and wire bonding. It is composed of two metallic layers: a layer of nickel protects the base copper layer from corrosion, and a layer of gold acts as an anti-corrosion layer for the nickel. ENIG is suitable for devices that require high levels of solderability and tight tolerances. ENIG is also lead-free.

Hard gold

Hard gold is a costly PCB surface finish. It is a high-quality, durable finish that is often reserved for components that see a high level of wear and tear. Hard gold is usually applied to edge connectors. Its main use is to provide a durable surface for components that undergo frequent actuation, such as battery contacts or keyboard contacts.

Hard electrolytic gold is a gold plated layer over a nickel barrier coat. It is the most durable of the two and is typically applied to areas that are susceptible to wear and tear. However, this surface finish is very expensive and has a low solderability factor.

Silver

Depending on the PCB’s composition, it can be produced with different colors and finishes. The three most common colors for PCB surfaces are silver, gold, and light red. PCBs with a gold surface finish are usually the most expensive, while those with a silver finish are cheaper. The circuit on the PCB is primarily made of pure copper. Because copper oxidizes easily when exposed to air, it is very important to protect the outer layer of the PCB with a protective coating.

Silver surface finishes can be applied using two different techniques. The first technique is immersion, in which the board is immersed in a solution containing gold ions. The gold ions on the board react with the nickel and form a film that covers the surface. The thickness of the gold layer must be controlled so that the copper and nickel can remain solderable, and the copper is protected from oxygen molecules.

Light red

The surface finish of a PCB can be glossy, non-glossy, or light red. A non-glossy finish tends to have a more porous look, and a glossy finish tends to be reflective and hard shell-like. Green is the most popular PCB color, and it’s also one of the least expensive. It’s important to clean PCBs before using them to avoid oxidation.

Although solder mask color isn’t a direct reflection of PCB performance, some manufacturers use it as a design tool. The color is ideal for PCBs that require brilliant visibility and sharp contrasts. Red PCBs are also attractive when combined with silkscreens.

Electroless palladium

Using the electroless palladium surface finish on your PCBs prevents the formation of black pads on the board, and has many benefits, including excellent solderability and aluminum and silver wire bonding. This type of finish also has an extremely long shelf life. However, it is also more expensive than other finishes and requires a longer lead time.

The ENEPIG PCB surface finish process involves several steps, each of which requires careful monitoring. In the first step, copper is activated, followed by the deposition of electroless nickel and palladium. After that, the circuit board goes through a cleaning procedure, to remove oxidation residues and dust from the surface.

Lead-free HASL

If you’re looking for a new PCB, you may wonder how to tell lead-free HASL surface finishes from lead-based PCBs. While HASL has an attractive look, it’s not ideal for surface-mount components. This kind of finish is not flat, and larger components, like resistors, can’t align properly. Lead-free HASL, on the other hand, is flat, and does not use lead-based solder. Instead, it uses a copper-based solder that is RoHS compliant.

HASL offers high-quality solderability, and it can withstand multiple thermal cycles. It was once the industry standard, but the introduction of RoHS standards pushed it out of compliance. Nowadays, lead-free HASL is more acceptable in terms of environmental impact, as well as safety, and is a more efficient choice for electronic components. It also aligns more closely with the RoHS directive.