Common pressure resistance problems of aluminum substrates Printed Circuit Board

Common pressure resistance problems of aluminum substrates printed circuit board

Frequently asked by netizens, the pressure resistance of aluminum substrates is OK when testing plates, but why do aluminum substrates fail when tested after molding?

So what is the main reason for the poor pressure resistance of aluminum substrates?

First of all, let's consider that the safety distance for aluminum substrates during design is too small. According to industry rules, the safety distance for conducting electricity (the distance from copper to aluminum) must be greater than 1mm at 1000V, greater than 2mm at 2000V, and greater than 3mm at 3000V. The safety distance mentioned here refers to the front edge of aluminum substrate molding, the front edge of the hole ring, and the offset of the hole position during molding. These three points are common problems in the production of aluminum substrate PCB factories.

Secondly, consider the forming hole deviation of the aluminum substrate: if there is a hole ring at the edge of the hole, this deviation will cause the hole ring to be too close to the aluminum substrate. In high voltage tests, due to the high voltage on the aluminum surface, a discharge phenomenon can form at the hole ring position, leading to upward ignition. It is possible to visually inspect the hole location for poor blackening points.

Consider the wear surface of the hole ring again: The main performance of the wear surface of the hole ring is poor treatment of the hole wall after molding, and there are debris in the hole. In high voltage testing, the power generated by the tip is caused by debris, and aluminum is unevenly discharged into the dielectric layer, leading to upward ignition, which can lead to visual inspection of defective points.

Final molding front: This is mainly because when there are burrs and sharp edges on the molding edge, during high-voltage testing, due to insufficient safety distance from the copper surface, the aluminum front end forms a tip discharge, with the ignition point located at the edge of the plate, and defect points can be seen near the copper surface of the plate edge.