Analysis on the Causes of Copper Plating on PCB Circuit Board

Analysis on the Causes of Copper Plating on PCB Circuit Board

PCB circuit board in the local collision, the copper wire by the external mechanical force and the base from. This phenomenon is bad positioning, off the copper wire will be significantly distorted, or to the direction of the scratches, impact marks. Poke the bad copper wire to see the copper surface, visible copper foil matte color normal, there will be no bad side erosion, copper foil peel strength is normal.

PCB circuit board design is unreasonable, with thick copper foil designed too fine lines will also cause excessive etching and copper rejection.

Copper foil etching over the market, the use of electrolytic copper foil is generally single-sided galvanized (commonly known as gray foil) and single-sided copper (commonly known as red foil), the common copper is generally more than 70um galvanized copper foil, Red foil and 18um below the ashes have not appeared in the bulk of the rejection of copper. If the customer's circuit is designed to pass through the etching line, if the copper foil specification is changed and the etching parameters are not changed, the residence time of the copper foil in the etching solution is too long. Because the zinc is inherently active metal, when the copper on the PCB for a long time in the etching solution soak, will lead to excessive side of the line erosion, resulting in some fine lines back layer of zinc is completely react off with the substrate, That is, copper off.

There is also a situation that PCB etching parameters are no problem, but the etching after washing, and poor drying, resulting in copper is also in the PCB surface of the residual surface of the etching solution surrounded by a long time untreated, will produce copper side And throw copper. This situation is generally reflected in the focus on the fine line, or the damp weather period, the whole PCB will appear similar to the bad, stripped of copper to see its contact with the grass-roots level (the so-called rough surface) color has changed, And the normal copper foil color is not the same, see the bottom of the original copper color, thick line copper foil peel strength is normal.