Why Is The Surface of Circuit Board Blistering

Understanding Circuit Board Blistering

Circuit board blistering is a common problem faced by electronics manufacturers and hobbyists alike. It occurs when the surface of a printed circuit board (PCB) develops raised bubbles or blisters, which can lead to various issues, including electrical shorts, component detachment, and reduced board reliability. In this article, we will explore the causes of circuit board blistering, its impact on PCB Performance, and preventive measures to minimize its occurrence.

What is Circuit Board Blistering?

Circuit board blistering is a defect characterized by the formation of raised, bubble-like protrusions on the surface of a PCB. These blisters can vary in size, ranging from small, localized bumps to large, widespread areas of delamination. Blistering typically occurs between the copper layer and the substrate material, such as FR-4 or polyimide.

Causes of Circuit Board Blistering

Several factors can contribute to the development of blisters on a circuit board’s surface:

1. Moisture Absorption: PCB Substrates, especially those made from hygroscopic materials like FR-4, can absorb moisture from the environment. During the soldering process, this trapped moisture vaporizes and expands, creating pressure between the layers and causing blistering.

2. Thermal Stress: Excessive heat during soldering or other manufacturing processes can lead to thermal stress within the PCB. If the temperature exceeds the Glass Transition Temperature (Tg) of the substrate material, it can cause delamination and blistering.

3. Improper Curing: Incomplete or improper curing of the PCB substrate during manufacturing can result in weak bonding between layers. This weakened bond is more susceptible to blistering when exposed to heat or moisture.

4. Contamination: The presence of contaminants, such as dirt, grease, or chemical residues, on the PCB surface can interfere with proper adhesion between layers. This can lead to localized blistering, particularly during soldering.

5. Material Incompatibility: Using incompatible materials or incorrectly matched coefficients of thermal expansion (CTE) between the copper layer and substrate can create stress during temperature changes, potentially causing blistering.

Impact of Circuit Board Blistering on PCB Performance

Circuit board blistering can have significant negative effects on the performance and reliability of a PCB:

1. Electrical Shorts: Blisters can cause the copper layer to separate from the substrate, creating air gaps that can lead to electrical shorts between adjacent traces or components.

2. Component Detachment: As blisters form and expand, they can cause components to lift or detach from the PCB surface, resulting in poor or lost electrical connections.

3. Reduced Reliability: Blistered PCBs are more prone to failure, especially when subjected to vibration, shock, or thermal cycling. The weakened bonding between layers can lead to premature failure of the board.

4. Aesthetic Issues: While not directly impacting performance, blistering can affect the visual appearance of a PCB, which may be a concern for some applications or customers.

Preventing Circuit Board Blistering

To minimize the occurrence of circuit board blistering, several preventive measures can be implemented:

1. Moisture Control: Proper storage and handling of PCBs in a moisture-controlled environment can help reduce the absorption of moisture by the substrate material. Using desiccant packs or baking the boards before soldering can also help remove any trapped moisture.

2. Temperature Control: Adhering to recommended soldering temperatures and profiles can minimize thermal stress on the PCB. Gradual heating and cooling cycles can also help reduce the risk of blistering.

3. Proper Curing: Ensuring that the PCB substrate is fully cured during manufacturing can improve the bonding strength between layers, making the board more resistant to blistering.

4. Surface Cleaning: Thoroughly cleaning the PCB surface before soldering can remove contaminants that may interfere with proper adhesion.

5. Material Selection: Choosing compatible materials with closely matched CTEs can help reduce stress between layers during temperature changes, minimizing the risk of blistering.

Detecting and Addressing Circuit Board Blistering

Visual Inspection

The most straightforward method for detecting circuit board blistering is through visual inspection. Blisters can often be seen with the naked eye, appearing as raised, bubble-like protrusions on the PCB surface. However, smaller blisters may require the use of magnification tools, such as a microscope or loupe, for better visibility.

X-Ray Inspection

For more thorough analysis, X-ray inspection can be used to detect blistering that may not be visible on the surface. X-ray images can reveal delamination between layers, as well as any voids or air gaps that have formed within the PCB.

Acoustic Microscopy

Acoustic microscopy is another non-destructive testing method that can be used to detect blistering. This technique uses high-frequency sound waves to create images of the internal structure of the PCB, allowing for the identification of delamination and other defects.

Repair and Rework

Once blistering has been detected, the affected PCBs may need to be repaired or reworked, depending on the severity of the issue. Small, localized blisters may be repaired by carefully removing the affected area and filling it with a suitable epoxy or other repair material. However, larger or more widespread blistering may require the complete removal and replacement of the affected components or board areas.

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” 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Industry Standards and Guidelines

Several industry standards and guidelines address the issue of circuit board blistering and provide recommendations for its prevention and management:

1. IPC-A-600: Acceptability of Printed Boards – This standard provides visual acceptance criteria for PCBs, including guidelines for evaluating blistering and delamination.

2. IPC-A-610: Acceptability of Electronic Assemblies – This standard offers acceptance criteria for electronic assemblies, including requirements for the inspection and evaluation of blistering on assembLED PCBs.

3. IPC-TM-650: Test Methods Manual – This manual contains various test methods for evaluating the quality and reliability of PCBs, including tests for moisture resistance, thermal stress, and delamination.

4. J-STD-001: Requirements for Soldered Electrical and Electronic Assemblies – This standard provides guidelines for the manufacture of soldered electronic assemblies, including recommendations for soldering processes and materials that can help minimize the risk of blistering.

By adhering to these industry standards and guidelines, manufacturers can improve the quality and reliability of their PCBs and reduce the occurrence of circuit board blistering.

Frequently Asked Questions (FAQ)

1. Q: Can circuit board blistering be prevented entirely?
   A: While it may not be possible to completely eliminate the risk of blistering, following proper manufacturing processes, material selection, and handling guidelines can significantly reduce its occurrence.

2. Q: Is it safe to use a PCB with minor blistering?
   A: Minor blistering may not immediately affect the performance of a PCB, but it can lead to further degradation over time. It is generally recommended to repair or replace blistered PCBs to ensure long-term reliability.

3. Q: Can blistering occur on both sides of a PCB?
   A: Yes, blistering can occur on either side of a PCB, depending on the location of the affected layers and the cause of the blistering.

4. Q: How does moisture absorption contribute to circuit board blistering?
   A: Moisture absorbed by the PCB substrate can vaporize and expand during soldering, creating pressure between layers and causing blistering.

5. Q: What are some common signs of circuit board blistering?
   A: Common signs of blistering include raised, bubble-like protrusions on the PCB surface, component detachment, and electrical shorts between traces or components.

Conclusion

Circuit board blistering is a serious issue that can significantly impact the performance and reliability of PCBs. By understanding the causes of blistering, such as moisture absorption, thermal stress, and material incompatibility, manufacturers can take steps to prevent its occurrence. Implementing proper manufacturing processes, material selection, and handling guidelines, as well as adhering to industry standards, can help minimize the risk of blistering and ensure the production of high-quality, reliable PCBs.

Regular inspection and testing, using methods such as visual inspection, X-ray imaging, and acoustic microscopy, can help detect blistering early and allow for timely repair or rework. By addressing blistering issues promptly and appropriately, manufacturers can maintain the integrity of their PCBs and provide customers with products that meet the highest standards of quality and reliability.

As the electronics industry continues to evolve and PCBs become increasingly complex, it is crucial for manufacturers to stay informed about the latest techniques and best practices for preventing and managing circuit board blistering. By doing so, they can remain competitive in a demanding market and deliver products that exceed customer expectations.