Top 5 PCB Manufacturing Issues and Their Impact on Your Boards
Manufacturing high-quality PCBs is critical for reliable electronics. However, several issues can arise during the process, affecting the board’s performance and lifespan. Below are the top five common PCB manufacturing problems, their causes, impacts, and preventive measures. This information is important for any rigid printed circuit board manufacturer or printed circuit board manufacturer striving for excellence.
1. Inner Layer Separations/Inclusions
Overview
Plated through-holes connect a PCB’s inner layers, enabling electrical conductivity. Any flaw in manufacturing can cause defects, leading to open circuits or intermittent electrical failures, particularly after thermal processes like soldering or rework.
Causes
- Inclusions/Debris: Contaminants such as drill debris, desmear residues, or filler powder disrupt the interconnect bond.
- Separation: Factors like improper lamination, moisture, defective prepreg, or residues from cleaning processes can cause copper layers to separate.
Prevention
- Use a consistent and effective drilling process.
- Optimize the desmear process to remove debris.
- Reduce resin content in the stack-up.
- Use materials resistant to chemical interactions and inorganic fillers.
2. Separation Between Plating Layers
Overview
This occurs when the bond between plating layers (e.g., electroless copper and electrolytic copper) weakens under thermal or mechanical stress, leading to intermittent or complete electrical failure.
Causes
- Incomplete wrap plating.
- Aggressive or insufficient cleaning processes.
Prevention
- Adjust plating parameters to ensure strong adhesion.
- Optimize cleaning steps to avoid weak bonding.
3. Copper Wicking Above 2.0 mil
Overview
Copper wicking happens when copper extends along the glass fiber fabric within the PCB, potentially causing electrical shorts between conductors.
Causes
- Dull or broken drill bits.
- Incompatible laminate material.
- Poor adhesion between glass fibers and resin.
Prevention
- Enhance drilling operations with better feed and speed control.
- Optimize desmear processes for thorough cleaning.
- Improve resin wet-out of glass fibers using siloxane treatments.
4. Internal Annular Ring Less Than 2.0 mil
Overview
An annular ring refers to the copper pad’s width around a drilled hole. When this ring is less than 2 mils, it increases the risk of layer breakouts during thermal processes, leading to electrical failure.
Causes
- Misaligned drilling patterns with inner layer lands.
- Improper lamination or pre-lamination treatments.
- Operator error or outdated design notes.
Prevention
- Choose higher-quality laminate materials.
- Ensure cleanliness during pre-lamination treatments.
- Update design notes to meet modern industry standards.
5. ENIG Thickness Below Minimum Requirements
Overview
Electroless nickel/immersion gold (ENIG) coatings must meet minimum thickness standards (118 micro-inches for Ni and 2 micro-inches for Au) to ensure proper solderability. Insufficient coating can cause uneven soldering, especially for tiny components like BGAs.
Causes
- Inadequate cleaning or rinsing processes.
- Non-compliance with chemical and pH requirements.
- Low bath temperatures or contaminants like oil on copper surfaces.
Prevention
- Use chemical cleaners or micro-etching to clean copper surfaces thoroughly.
- Improve rinsing processes, including water quality and flow.
- Adjust bath temperatures and operational parameters as per supplier specifications.
Conclusion
By addressing these top PCB manufacturing issues, rigid printed circuit board manufacturers and printed circuit board manufacturers can improve product quality and reliability. Preventive measures, such as optimizing drilling, cleaning, and lamination processes, are essential for minimizing defects. Investing in high-quality materials and adhering to industry standards ensures better performance and customer satisfaction.
