During the manufacturing process of PCB circuit board, the copper wire of the circuit board often falls off badly, which is also often referred to as copper throwing, thus affecting the product quality. Then, what are the common reasons for copper throwing of PCB?
1、 PCB process factors:
1. The copper foil is excessively etched. The 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 Redding foil). The common copper rejection is generally ashing foil above 70UM. The Redding foil and ashing foil below 18um basically do not have batch copper rejection.
2. Local collision occurs in PCB process, and the copper wire is separated from the substrate by external mechanical force. This defect is manifested as poor positioning or directionality, and the dropped copper wire will have obvious distortion or scratches / impact marks in the same direction.
3. The PCB circuit design is unreasonable. If the circuit is too thin with thick copper foil, the circuit will be etched excessively and copper will be thrown away.

2、 Laminate process reason:
Under normal circumstances, as long as the laminate is hot pressed for more than 30min, the copper foil and the prepreg are basically completely bonded. Therefore, the bonding force between the copper foil and the substrate in the laminate is generally not affected by the compression. However, in the process of laminating and stacking of laminates, if PP is polluted or the rough surface of copper foil is damaged, the bonding force between copper foil and substrate after lamination will be insufficient, resulting in positioning (only for large plates) or sporadic copper wire falling off.
3、 Reason for raw material of laminate:
1. Ordinary electrolytic copper foils are products that have been galvanized or copper plated with wool foils. If the peak value of wool foils is abnormal during production, or if the plating crystal branches are poor during galvanizing / copper plating, the peeling strength of the copper foil itself is insufficient. When the poor foil pressed plate is made into PCB and inserted into the electronic factory, the copper wire will fall off under the impact of external force.
2. Poor adaptability of copper foil and resin: when the copper foil is used in the production of laminate, it does not match the resin system, resulting in insufficient peeling strength of the metal foil covered by the plate, and poor copper wire peeling will also occur during the plug-in.