1. PCB short circuit caused by unclean etching
1. The quality of etching potion parameter control directly affects the etching quality.
二. visible PCB micro-short circuit
1. The micro-short circuit of the line caused by the scratch of the Mylar film on the exposure machine;
2. The circuit is slightly short-circuited due to scratches on the glass on the exposure disk.
三. PCB short circuit caused by running tin
1. The sheets that have been removed from the film are superimposed together to cause tin running;
2. Improper operation in the stripping potion tank will cause tin running.
四. the fixed position PCB short circuit
The main reason is that the film line is scratched or there is garbage on the coated screen, and the coated anti-plating layer is fixed with exposed copper, resulting in a short circuit.
五. Invisible PCB micro-short circuit
For our company, invisible micro-short circuit is the most troublesome and once the most difficult problem to solve. Among the finished boards with problems in the test, about 50% belong to this kind of micro-short circuit problem. The main reason is the line spacing. There are wires or metal particles that are invisible to the naked eye.
六. sandwich PCB short circuit
1. The anti-coating layer is too thin. When the coating exceeds the film thickness during electroplating, an interlayer is formed. Especially, the smaller the line spacing, the easier it is to cause interlayer short circuit;
2. The pattern distribution of the board is uneven. During the pattern plating process of several isolated lines, due to the high potential, the plating layer exceeds the film thickness, resulting in a short circuit due to the formation of a sandwich film.
七. scratched PCB short circuit
1. The connection board at the outlet of the developing machine is too busy to cause collision and scratches between the board and the board;
2. Scratches after coating the wet film, and the film surface is scratched due to improper operation during alignment;
3. Improper taking of the plate during electroplating, improper operation when placing the splint, improper operation when the plate is handled before the manual line, etc., resulting in scratches.