The following outlines major issues encountered with substrates in PCB design, including their symptoms, possible causes, inspection methods, and solutions.

1. Soldering Problems

Phenomenon:

• Cold solder joints or solder joints with blowout holes.

Inspection Method:

• Analyze holes before and after dip soldering to identify copper stress points.
• Perform rigorous incoming material inspections on raw substrates.

Possible Causes:

• Poor copper plating leads to expansion during soldering, causing cavities or blowout holes.
• Absorbed volatiles during wet processing are sealed by plating and released during soldering, forming blowout holes.

Solutions:

1. Eliminate copper stress by addressing material expansion in the z-axis (thickness direction). Work with laminate manufacturers to select materials with lower z-axis expansion.
2. Enhance material quality control during the wet processing stage.

2. Bonding Strength Issues

Phenomenon:

• Pads or wires detach during dip soldering or other operations.

Inspection Method:

• Conduct sufficient incoming material testing and closely monitor wet processing steps.

Possible Causes:

1. Solvent or electroplating erosion weakens bonds.
2. Drilling or punching damages pad integrity, worsening during hole metallization.
3. Improper soldering techniques or excessive soldering temperatures.
4. PCB design flaws, such as sharp corners or long traces with poor thermal expansion compatibility.
5. Heat retention during soldering causes delamination.

Solutions:

1. Provide laminate manufacturers with detailed process specifications, including solutions, time, and temperature.
2. Adhere strictly to recommended mechanical processing methods and frequently analyze metallized holes.
3. Train operators on soldering best practices to prevent damage from excessive heat or improper tools.
4. Redesign problematic PCB layouts to reduce stress concentrations, particularly for thick copper foil or sharp angles.
5. Shift heavy component installation to post-dip soldering stages or use low-wattage soldering irons for manual operations.

3. Excessive Size Change

Phenomenon:

• Substrate dimensions are out of tolerance or fail to align after processing.

Inspection Method:

• Implement comprehensive quality control at each processing stage.

Possible Causes:

1. Structural texture direction of paper-based materials affects expansion, with longitudinal expansion being half of lateral expansion.
2. Irregular dimensional changes due to unreleased local stress in the laminate.

Solutions:

1. Train personnel to consistently cut boards following the structural texture direction. If size variation persists, consider alternative substrate materials.
2. Work with laminate manufacturers to determine proper stress-relief processes before production.

As a leading PCB manufacturer, members of our printed circuit board (PCB) design service team are practical partners working with you on every project and can help you achieve your goals at any time. They can complement your engineering expertise, which helps speed up time to market, reduce the time from concept to production, and ensure that quality is integrated into the manufacturing process to maximize your profits.