How to deal with the circular watermark on the hole edge of PCB plating

- Oct 17, 2018-

Phenomenon: single board, whole board, each hole has, hole edge, water grain shape, like the condition after natural air drying of washing dirty residual liquid.

Possible causes and solutions:

The phenomenon was called fisheye phenomenon, PCB design is the phenomenon and electroplating luster agent and solution of chlorine content in the relationship, if the residual of grain is pure water, the more likely reason is washed before drying is not complete, the residual liquid in the drying of a hole out of dry water line phenomenon due to the plate, this kind of phenomenon is especially with the more likely to happen, or deep hole water lines should be tear-drop shaped instead of concentric circles, and a cup of hole edge there will be part of the drying of the region caused by bleaching powder water marks, such phenomenon in principle will help improve water washing.