When PCB copper wires fall off (also known as copper dumping), PCB brands will argue that laminate is the problem and require their production plants to bear bad losses. According to years of customer complaint handling experience, the common reasons for PCB copper rejection are as follows:

I. PCB factory manufacturing process factors:

1, excessive copper foil etching. Electrolytic copper foil used in the market is generally single-sided galvanized (commonly known as ashing foil) and single-sided copper plating (commonly known as red foil), common copper dumping is generally galvanized copper foil above 70um, red foil and ashing foil below 18um have not appeared in bulk copper dumping. When the circuit design is better than the etching line, if the copper foil specifications change but the etching parameters remain unchanged, the copper foil will stay in the etching solution for too long.

Because zinc is an active metal, when the copper wire on PCB is immersed in etching solution for a long time, it will lead to excessive side erosion of the line, resulting in some fine line backing zinc layer is completely reacted off and separated from the base material, that is, the copper wire falls off. Another situation is that there is no problem with the ETCHING parameters of PCB, but the washing and drying after etching are poor, resulting in the copper wire is also surrounded by the etching liquid remaining on the SURFACE of PCB. If it is not treated for a long time, excessive side erosion of copper wire will also occur and copper will be thrown. This kind of situation usually focuses on the fine lines, or period of wet weather, the PCB will appear similar adverse, remove the copper wire to see its and grassroots interface (so-called coarsening surface) color have change, unlike normal copper foil color, is to see the underlying original copper color, thick lines of copper foil peel strength also normal.

2. In the process of PCB production, there is a local collision, and the copper wire is separated from the base material by external mechanical force. This bad performance of positioning problems, peeling copper wire will have significant distortion, or to the same direction of the scratch or impact mark. Peeling the copper wire at the bad place to see the copper foil hair surface, you can see that the color of the copper foil hair surface is normal, there will be no bad side erosion, and the copper foil peel strength is normal.

3. PCB circuit design is unreasonable. Using thick copper foil to design too thin line will also cause excessive etching of the line and throw copper.

Two, laminate process reasons:

Under normal circumstances, as long as the laminate is pressed at high temperature for more than 30 minutes, the copper foil and the semi-cured sheet are basically combined completely, so the pressing generally does not affect the binding force of the copper foil and the base material in the laminate. However, in the process of laminate stacking and stacking, if PP pollution or copper foil hair surface damage, it will also lead to insufficient binding force between copper foil and the base material after lamination, resulting in positioning deviation (only for the large plate) or sporadic copper wire falling off, but there will be no abnormal copper foil peeling strength near the measured off line.

Three, laminate raw materials:

1, the above mentioned general electrolytic copper foil MAO foil galvanized or copper plating the processed products, when MAO foil production peak is abnormal, or zinc/copper plating, coating the dendrite, the peel strength of the copper foil itself is not enough, caused by the bad foil after pressing sheet made PCB electronics factory plug-in, copper wire fall off by external shocks will occur. This kind of bad copper stripping copper wire to see the copper foil hair surface (that is, the contact surface with the base material) will not have obvious side erosion, but the whole surface of the copper foil peeling strength will be very poor.

2, the adaptability of copper foil and resin is poor: some special performance laminate used now, such as HTG sheet, because the resin system is not the same, the curing agent is generally PN resin, resin molecular chain structure is simple, the crosslinking degree is low when curing, is bound to use special peak copper foil and match. When the copper foil used in the production of laminate does not match the resin system, the stripping strength of sheet metal foil is not enough, and the copper wire will fall off badly when the plug-in is used.

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