In the manufacturing of printed circuit boards (PCBs), various problems can easily arise, one of which is the falling off of copper foils. If the problem cannot be identified, it will directly affect the quality and reliability of the product. Therefore, this article will analyze the reasons for the falling off of copper foils, hoping to help everyone.
1. Excessive Etching of Copper Foil
When the copper foil stays too long during the etching process, especially when using galvanized copper foil, the reactivity of zinc can easily lead to the complete reaction of the zinc layer on the fine line backing, causing the copper foil to separate from the substrate. Additionally, poor washing and drying after etching can lead to residual etching solution continuously eroding the copper foil, resulting in copper shedding.
2. Mechanical Collision
During the PCB production process, localized collisions may cause the copper wire to detach from the substrate due to external forces. The fallen copper wires in such cases usually show obvious twists or scratches.
3. Unreasonable Circuit Design
Using too thick copper foil to design excessively fine lines makes it difficult to control the etching accurately, which can easily cause over-etching of the lines, leading to copper shedding.
4. Laminate Stacking Issues
During laminate stacking, if the prepreg (PP) is contaminated or the surface of the copper foil is damaged, it will lead to insufficient bonding strength between the copper foil and the substrate, causing the copper wires to fall off.
5. Defects in Copper Foil Quality
Abnormal peaks during copper foil production or poor plating dendrites will directly affect the peel strength of the copper foil, making it prone to falling off due to external impact in subsequent processes such as insertion.
6. Poor Compatibility Between Copper Foil and Resin
Specific performance laminates (such as HTg materials) require copper foils with specific peak values for matching. If not matched, it will lead to insufficient bonding strength between the copper foil and the resin, resulting in the falling off of copper wires.
This article is an original piece by Fan Yi Education; please indicate the source if reprinted!