Do you know what defects of flexible circuit board might be? Today Vility share some common defects and solutions for you.
1. Bubble is formed after the side of the flexible circuit board line or single line is unfolded.
The main reason: bubbles are generated between two or more lines, mainly because the line spacing is narrow and the lines are too high, making it impossible to print solder resist on the substrate during screen printing, resulting in the gap between the solder and the substrate. Generate air or moisture. During the curing and exposure process, the thermal expansion of the gas caused by the gas is mainly caused by the high wire.
When the blade is in contact with the wire, the angle between the squeegee and the wire increases, making the solder resist unable to print to the root of the wire the root of the weld, so that there is gas between the root of the weld and the resist layer of the weld, and bubbles are generated after heating.
Solution: When screen printing, it is necessary to check whether the screen material is completely printed on the side wall of the substrate and the line, and strictly control the current during electroplating.
2. Flexible circuit board holes with resistance soldering and patterned pinholes
The main reason: the flexible circuit board does not print the paper in time during the screen printing process, resulting in excessive accumulation of residual ink in the screen, and the residual ink is sent into the hole under the pressure of the scraper, and the number of screens is too small. Causes welding resistance in the hole. Dirt on the photographic base plate, preventing the flexible circuit board from seeing light during exposure, causing pinholes in the pattern.
Solution: Use high-mesh printing paper and screen plate in time, and check the cleanliness of the photo plate frequently during exposure
3. The copper foil wire under the resistance welding layer of the flexible circuit board shows signs of blackening.
The main reason: the flexible circuit board is not dry after wiping, and the surface of the printed circuit board is splashed by liquid or manual molding before printing resistance welding.
Solution: Oxidation of copper foil on both sides of the printed board by screen printing.
The above three defects are common, hope our suggestions can help you solve the problems.