PCB copper plant rejection common three main reasons

- Jul 28, 2016-

PCB plant process factors

1, excessive copper foil etching, electrolytic copper foil used on the market generally sided galvanized steel (commonly known as ash foil) and single-sided copper (commonly known as the red of the foil), a common rejection of copper is generally more than 70um galvanized copper foil, reddening 18um foil and foil the following basic ashing none appeared the bulk of the rejection of copper. Customer etched circuit design is better than the line, after a specification change and if the copper foil etching parameters unchanged, resulting in a copper etching solution in the long residence time. Because zinc metal has always been active, when copper PCB on a long soak in the etching solution, will lead the line-side excessive erosion, causing some of the fine lines of the backing layer of zinc is completely reacted with the substrate detachment, That copper wire off. Another case is PCB etch parameters there is no problem, but after etching poor washing and drying, resulting also in a copper etching liquid surface will be surrounded by PCB residues in untreated for a long time, it will produce excessive side etching copper rejection copper. This case focused on the general performance of thin road or weather wet period, the entire PCB will appear similar to the poor, stripped copper wire to see with the primary contact surface (the so-called roughened surface) has changed color, normal copper color is not the same, see the bottom of the original copper color, copper foil peeling strength at the crude line also normal.

2, PCB collision processes occur locally, copper wire by external mechanical forces from the substrate. This poor performance is poor positioning or fixed directional, copper loss will be significantly distorted, or to scratch the same direction / impact marks. Look at the copper foil peel bad hair surface, you can see the color of the matte side of the copper foil normal, there will be no adverse side etching copper foil peeling strength properly.

3, PCB circuit design is unreasonable, meticulous design with thick copper lines, can also cause excessive rejection of copper etching lines.


Laminate process 

Under normal circumstances, as long as the hot high temperature laminates segment more than 30min after the copper foil and prepreg basically complete the combination, so nip generally will not affect the binding force of the copper foil laminate to the substrate. But with laminate stack, stacking process, if PP contamination or damage copper matte, can lead to insufficient binding force after the copper foil laminated to the substrate, resulting in positioning (only for large plate words) or sporadic copper loss, but near the copper foil peeling strength measured off-line will not be an exception.


Laminate material

1, the above mentioned ordinary electrolytic copper foil, zinc or copper wool are treated product, if abnormal hair foil production will peak, or zinc / copper, the coating dendrites bad, causing the foil itself peel strength is not enough, the poor after pressing the foil sheet made of PCB factory will fall off in the electronic plug-in, the copper wire by external shocks. Such rejection copper foil look bad ripping copper matte (ie contact with the substrate surface) is not obvious after side etching, but the entire surface of the copper foil peeling strength will be poor. 

2, poor adaptability copper foil and resin: special properties of the laminate is now used as HTg sheet, because the resin system is not the same, the curing agent is generally PN resin, the resin molecular chain structure is simple, when cured low crosslinking degree, is bound to use a special peak foil match. Use when producing laminate foil and the resin system does not match, resulting in sheet metal-clad peel strength is not enough, there will be bad plugin copper off.

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