During the production process of PCB circuit boards, it is often encountered that the copper wires of the circuit boards fall off poorly, which is also often referred to as copper throwing, which affects product quality. So, what are the common reasons for PCB circuit board throwing copper?
一. PCB circuit board process factors:
1. Copper foil is over-etched. The electrolytic copper foil used in the market is generally single-sided galvanized (commonly known as ashing foil) and single-sided copper-plated (commonly known as red foil). , The reddish foil and the ashed foil below 18um have basically no batch copper throwing.
2. Partial collision occurs during the PCB process, and the copper wire is separated from the substrate by external mechanical force. This defect is manifested as poor positioning or , obvious distortion of the peeled copper wire, or scratches/impact marks in the same direction.
3. The PCB circuit design is unreasonable. If the circuit is too thin to be designed with thick copper foil, it will also cause excessive etching of the circuit and throw away copper.
二. Reasons for the laminate process:
Under normal circumstances, as long as the laminate is hot-pressed at a high temperature for more than 30 minutes, the copper foil and the prepreg are basically fully bonded, so the pressing will generally not affect the bonding force between the copper foil and the substrate in the laminate. However, in the process of stacking and stacking laminates, if PP is polluted or the rough surface of the copper foil is damaged, the bonding force between the copper foil and the substrate after lamination will also be insufficient, resulting in positioning (only for large boards) words) or sporadic copper wires fall off.
三. Reasons for laminate raw materials:
1. Ordinary electrolytic copper foil is a product that has been galvanized or copper-plated. If the peak value of the raw foil is abnormal during production, or the crystal dendrites of the plating layer are poor during galvanizing/copper plating, the peel strength of the copper foil itself is not enough. , When the bad foil pressing sheet is made into PCB and plugged in in the electronics factory, the copper wire will fall off under the impact of external force.
2. Poor adaptability between copper foil and resin: When producing laminates, the copper foil used does not match the resin system, resulting in insufficient peeling strength of the metal foil on the sheet, and poor copper wire shedding when plugging in.
