I. PCB process factors:
1, excessive copper etching, electrolytic copper foil on the market for the general use of single zinc (commonly known as ashing and single copper foil) (commonly known as red foil), common copper is copper zinc dumped more than 70UM, red foil and 18um foil have not seen the ashing batch rejection of copper. When the customer line design is better than the etching line, if the etching parameter of the copper foil specification is changed, the copper foil stays too long in the etching solution. Because of zinc is the active metal, when PCB copper etching solution in long time immersion, will lead to excessive erosion caused by the line side, some fine line backing zinc layer is completely lost and the reaction with the substrate detachment, namely copper loss. There is also a case of PCB etching parameters is no problem, but after etching and washing, drying, resulting in copper etching liquid surrounded by surface residual PCB in untreated long time, will produce excessive lateral erosion and rejection of copper wire. This is generally concentrated in the fine way, or the weather is wet period, there will be a similar adverse PCB on the contact surface and the peel copper base (so-called rough surface) color has changed, unlike normal copper color, see the bottom of the original copper color, thick lines where the peel strength is also normal.
2, the PCB process of local collision, copper wire under external mechanical and material detachment. The bad performance is bad positioning or directional, the copper wire will be obvious distortion, or to the same direction of scratch / impact mark. Peeling bad copper wire to see copper foil surface, you can see the copper foil hair surface color is normal, there will be no side corrosion, copper foil peeling strength normal.
3, PCB line design is not reasonable, with a thick copper foil design fine lines, can also cause excessive etching and rejection of copper.

Two, laminate process reasons:
Under normal circumstances, as long as the hot pressing section of the laminate exceeds 30min, the copper foil and the semi cured sheet are basically combined, so the bonding force of the copper foil and the base material are not influenced by the press bonding in general. But in the process of laminate stacking, stacked, or if the PP pollution, copper hair surface damage, can also cause after lamination combined with the copper foil and substrate power is insufficient, resulting in positioning (only for large terms) or sporadic copper loss, but measured near the peel strength off-line will not have abnormal.

Three, laminate raw material reasons:
1, above mentioned ordinary electrolytic copper foil is galvanized or copper foil treated hair products, hair foil production peak if abnormal, or galvanized / plating, plating dendrites bad, causing peel strength copper foil itself is not enough, the bad press foil plate into PCB in electronic factory plugin, the copper wire by the external shock will occur off. This kind of poor copper stripping, copper wire to see copper foil surface (that is, contact with the substrate) will not be obvious side corrosion, but the entire surface of copper foil peel strength will be poor.
2, copper foil with resin adaptability: some special properties now use the laminate sheet, such as HTg, because the resin system is not the same, the curing agent is PN resin, the resin molecular chain has the advantages of simple structure, curing with low crosslinking degree, is bound to the use of special copper peak matching. When the laminate is used, the copper foil does not match the resin system, resulting in the insufficient peeling strength of the sheet metal coating, and the copper sheet falling off during the plug-in.