PCB Manufacturing

Common PCB Defects and How to Identify Them

PCB defect

While manufacturing any product, there is always a chance of getting some defective pieces in the production. This is an unavoidable phenomenon even if we follow strict regulations at the time of manufacture. The same happens with the case of PCB designs and manufacturing. There are always some common printed circuit board defects and these PCB defects can also occur later on in PCB production.

In this article, we are going to have a clear idea of common PCB defects and how we can identify them. So, let’s embark together and find out about it effectively.

What Are Common PCB Defects?

A PCB defect is any irregularity or imperfections in the board design or any malfunctioning of the PCB that may affect its overall performance. They will highly influence the reliability and durability of the PCB and its overall performance resulting in poor working and inefficient output.

Some common printed circuit board defects are listed below in detail:

  1. Solder Bridges: This PCB defect can occur because of the unintentional connection or joining of traces or maybe pads while soldering. This can lead to short circuits and failure of the circuit.
PCB defect:Solder bridges

PCB defect:Solder bridges

 

Common PCB defect:Solder bridges

Common PCB defect:Solder bridges

  1. Insufficient solders: Sometimes, more solder in the required area can prevent poor connections. This may also lead to the open circuit which happens when the connection between two points is disrupted or broken. This will lose the ability to conduct electricity properly in the circuitry
  2. Lifted pads or traces: When there is mechanical stress and shocks or due to improper handling of the PCBs, the pads and traces in the PCB might get lifted from the PCB surface.
Common PCB defect:Solder bridges

Common PCB defect:Solder bridges

  1. Misaligned components: The components might need to be aligned with the pads properly sometimes and this may lead to poor connections and conductivity problems. This PCB defect can be identified by looking for components that seem misaligned or crooked. You can also check the component data sheet and refer to its blueprint which shows its orientation might also help.
  2. Cold solder Joints:  When the solder hasn’t bonded with the component lead, this PCB defect occurs. This defect usually appears dull or grainy instead of shiny and smooth surfaces like proper solder joints. By visual inspection, this PCB defect can be easily identified.
PCB defect:Cold solder Joints

PCB defect:Cold solder Joints

  1. Cracked or broken PCB: The PCB with a cracked or broken area will have a high contribution to PCB malfunctioning. This will lead to breaks in the copper traces and component connections eventually causing malfunction.
  2. Common copper trace damage: Some of the common copper trace damages are due to factors like an overload of current, mechanical stress or shocks and some environmental factors. The bare PCB defects are so common yet relevant. Because of the importance of copper traces in PCBs, this must be identified quickly.
  3. Flaws in Design: The errors while designing the PCB layout are a common thing in the occurrence of printed circuit board defects. Sometimes, designers while designing, will overcrowd the components or make insufficient clearance between traces and this can cause severe performance problems.
  4. Error while manufacturing: During the PCB manufacturing process, there might be lots of manufacturing errors occurring like incorrect etching, drilling inaccuracy and plating problems. This will affect the efficiency of the end product as a PCB.
  5. Corrosion and contamination:  Due to some chemical reactions and some environmental factors, corrosion can occur to PCB boards leading to problems in electrical conductivity and overall performance.

Also, in the case of contaminations like dirt, dust, etc. the PCB will react very badly, which will lead to poor electrical contact, short circuits and other malfunctions.

PCB defect:Corrosion and contamination

PCB defect:Corrosion and contamination

How to Identify Common PCB Defects?

The identification process of PCB can be boundless for many of the printed circuit board defects. We can find out the problem in lots of methods to find out what is exactly happening with the devices. These PCB defect detection can be sometimes very simple like a visual inspection and could go up to a much more complex process.

Some general identification procedures are mentioned below:

Visual Inspection

This is the common and primary PCB defect detection. Here, the examination is done visually with careful inspection to check for any abnormalities or misplacements. Inspection including:

  • Component Inspection: Checking components for proper placement, orientation and quality.
  • Solder Joint Inspection: Checking solder joints for printed circuit board defects like cold solder joints, excessive solder, solder bridge, solder balls or insufficient solder.
  • Trace and Pad Inspection: Checking for damage, breaks or shorts in copper traces and pads.
  • Overall Board Inspection: Checking for any cracks, scratches, delamination or any physical damage on the PCB surface.

Functional Testing

This verifies that the PCB is operating in the desired manner according to its intended design and features. Some of the functional tests are listed below:

  • Power-On Test: This test involves applying power to the PCB and checking for things like smoke, overheating, etc. from the PCB.
  • Signal Testing: With the help of oscilloscope, multimeters and other logical analyzers, the signals are measured at various points on the PCB. These values can be compared with expected values to find abnormalities.
  • Boundary Scan testing: This can verify the integrity of connections between the components for complex interconnected PCBs.

Automated Optical Inspection (AOI)

PCB defect detection:AOI

They use high-definition cameras and image processing algorithms which can be helpful in inspecting PCBs accurately. This inspection will help in detecting solder joint defects, placement errors of components and formation of Solder Bridges, etc.

X-ray Inspection

This is very helpful in examining the internal structure of PCBs and identifying whether there are any solder joints, internal defects or component connections, especially in BGA soldering quality inspection.

In-circuit Testing (ICT)

This identification process involves the testing of the electrical characteristics of individual components as well as the interconnections in the PCB. This testing can find printed circuit board defects like open circuits, short circuits, etc.

Thermal Imaging

The cameras which support thermal imaging can detect the abnormal temperature distribution on PCB. This is shown in the camera due to potential printed circuit board defects like short circuits, overflow of current or may be of component overheating.

 

Conclusion

To conclude, we can say that the identification of PCB defects is necessary for ensuring proper functionality, reliability and overall quality of the PCBs. We should always follow a systematic approach to finding printed circuit board defects, such as visual inspection, functional testing, using a multimeter for continuity checks, X-ray inspection or following in-circuit testing (ICT). The primary method to find out is always visual inspection and we can find many of the PCB defects by this method.

By always implementing inspection and checking throughout PCB manufacturing, we can minimize PCB defects and optimize production efficiency. Regular checking and quality control can reduce defects and will help in improving the production quality and satisfaction of customers.

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