In the process of producing double-sided or multi-layer PCB, it is generally used the following steps.
Punching – chemical immersion copper – full board thickening copper plating – pattern transfer – circuit copper plating – alkaline etching – production process
The purpose of thickening electroplating copper on the whole board is to increase the strength of the electroless copper layer.
Due to the uneven distribution of the current density during the copper electroplating process, the thickness of the copper surface of the entire board will be uneven.
In the part with high current density, the thickness of copper is large.
In the part where the current density is low, the thickness of copper is small.
In this way, during the alkaline time, if the complete etching is achieved, overetching will occur in the part with a small copper thickness.
One-step copper electroplating to produce PCB process:
Punching – chemical immersion copper – pattern transfer – circuit copper plating – alkaline etching
This process avoids the local over-etching phenomenon mentioned above because there is no full-board thickening electroplating copper process.
At the same time, since the thickness of the corroded copper layer is smaller than that of the secondary copper plating process, the over-etching phenomenon of the whole board can also be better controlled.
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