During the production process of PCB circuit boards, it is common to encounter poor copper wire detachment, also known as copper throwing, which affects product quality. So, what are the common reasons for PCB circuit board copper throwing?

1、 PCB process factors:

1. Copper foil is excessively etched, and the electrolytic copper foil used in the market is generally single-sided galvanized (commonly known as ashed foil) and single-sided copper plating (commonly known as reddened foil). The common copper throwing is generally ashed foil above 70um, while reddened foil and ashed foil below 18um have not undergone bulk copper throwing.

2. Local collisions occurred during the PCB process, causing the copper wire to detach from the substrate due to external mechanical forces. This defect manifests as poor positioning or directionality, where the detached copper wire will have obvious twisting or scratches/impact marks in the same direction.

3. Unreasonable PCB circuit design, using thick copper foil to design overly fine circuits, can also cause excessive etching of the circuit and copper throwing.

2、 Reason for Laminate Manufacturing Process:

Under normal circumstances, as long as the hot pressing temperature range of the laminate exceeds 30 minutes, the copper foil and the semi cured sheet are basically fully bonded, so pressing generally does not affect the bonding force between the copper foil and the substrate in the laminate. However, during the process of lamination and stacking, if PP is contaminated or the rough surface of the copper foil is damaged, it can also lead to insufficient adhesion between the laminated copper foil and the substrate, resulting in positioning (only for large boards) or sporadic detachment of copper wires.