1. PCB short circuit caused by tin running

1. Tin run caused by improper operation in the receding film medicine tank;

2. The plate that has retreated the film is superimposed together to cause tin running.

Second, PCB short circuit caused by unclean etching

1. The quality of etching potion parameter control directly affects the etching quality.

3. Visible PCB microshort circuit

1. Micro-short circuit caused by Myra film scratch on the exposure machine;

2, exposure plate on the glass scratches caused by the line micro short circuit.

Four, clip film PCB short circuit

1. The anti-coating layer is too thin. When plating, the coating exceeds the thickness of the film, forming the clip film, especially the smaller the line spacing, the easier it is to cause the short circuit of the clip film.

2. Uneven distribution of plate graphics. In the process of graphic electroplating, the coating of isolated lines exceeds the thickness of the film due to high potential, resulting in short circuit caused by clamping film.

Five, invisible PCB microshort circuit

Invisible micro-short circuit is the most troubling problem for our company for a long time and has been the most difficult problem to solve. About 50% of the finished boards with problems in the test are such micro-short circuit problems. The main reason is that there are metal wires or metal particles invisible to the naked eye in the line spacing.

Six, fixed PCB short circuit

The main reason is that the film line is scratched or there is garbage blocking on the coated screen plate, and the coated anti-coating fixed position exposed copper leads to short circuit.

Seven, scratch PCB short circuit

1, wet film coating after scratch, improper operation caused by film surface scratch.

2. The developing machine outlet plate is too busy to cause the collision and scratch between the plate and the plate.

3. Scratches are caused by improper plate taking during electroplating, improper operation during splint putting, improper operation during plate handling before manual line.