Printed Board Product Troubleshooting Tips

When dealing with issues related to printed board products, it’s crucial to address potential problems that may arise with the PCB product itself. These issues can present themselves in the form of warpage, solder mask problems, and irregular characters.

Common Problems and Solutions:

• Warpage: Sometimes, the hot air leveling process is skipped during production, leading to potential warpage issues. To prevent this, ensure that the product is properly heated before testing to avoid warpage beyond acceptable limits. Adding a warpage measurement step before testing is recommended.
• Solder Mask: Products with open circuits may be due to via holes blocked by the solder mask layer. When testing, be mindful of not testing transfer holes or ensure accurate hole guide passage to avoid this issue.
• Characters: PCB manufacturers often print characters before electrical measurements. However, offset characters or inaccuracies in the character film can lead to partial coverage of surface stickers and small holes, causing open circuits. It’s advisable to measure PCBs with thin surface mounts, small holes (Φ<0.5), and high-density thin lines electrically before printing characters.

Difference Between Flying Probe Test and Fixture Test:

• A flying probe tester utilizes the capacitance method and swiftly moves point by point on the circuit board for testing.
• Conduct standard board learning initially and read the standard capacitance value of each network.
• Start with the capacitance method and use the resistance method for precise confirmation if the measured capacitance falls outside the acceptable range.
• Four-wire measurement is an option for testing.
• It’s best suited for testing samples with small batches due to its slower speed.

Advantages and Disadvantages of Flying Probe Testing:

• Advantages:
• High test density, with a minimum pitch as small as 0.05mm or even smaller.
• No fixture costs involved.
• Disadvantages:
• Test pins are prone to damage.
• Testing speed is slower.
• Unable to test withstand voltage, posing a higher risk for high-level high-density board tests.