PCB News - Does the PCB circuit board always have bad copper wires falling off?

Does the PCB circuit board always have bad copper wires falling off?

Usually, in the process of making PCB circuit board, we often encounter some process defects, such as the poor copper wire of the PCB circuit board, which means that copper is thrown off, which reduces the quality of the product. There are two reasons that cause the PCB circuit board to dump copper.

A, PCB circuit board process factors are explained as follows

1. Copper foil is over-etched. The electrolytic copper foil used on the market is usually single-sided galvanized (commonly known as ashing foil) and single-sided copper plating (commonly known as red foil). The more common copper foil is usually more than 70um galvanized. Copper foil, red foil and ash foil below 18um have almost no batch copper rejection.

2. Local bumps occur in the PCB process, and the copper wire is subjected to external mechanical force and the substrate is separated. This defect is manifested in poor positioning or orientation, and the copper wire that is dropped off will show obvious twisting, or scratches/impact marks in the same direction. Peel off the copper wire at the defective part and check the rough surface of the copper foil, you can see that the color of the rough surface of the copper foil is normal, there will be no side erosion, and the peeling strength of the copper foil is normal.

3. The PCB circuit is not properly designed, and the thick copper foil is used to design the circuit that is too thin, which will also cause the circuit to be over-etched and the phenomenon of copper rejection.

B. The reasons for the laminate manufacturing process are explained as follows

Under normal circumstances, the laminate only needs to be hot pressed for more than 30 minutes after the high temperature section, the copper foil and the prepreg are basically completely combined, so the pressing usually does not affect the bonding force of the copper foil and the substrate in the laminate. However, in the process of stacking and stacking laminates, if the PP is contaminated or the matte surface of the copper foil is damaged, it will also cause insufficient bonding between the copper foil and the substrate after lamination, resulting in positioning or sporadic copper The wire falls off, but the peeling strength of the copper foil near the off wire will not be abnormal.

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