Circuit board drilling quality defects are divided into drilling defects and hole defects; drilling defects include leaks, holes, holes, wrong hole diameters, offset holes, broken drill bits, and non-penetration; hole defects are divided into copper foil and base Material defects. These defects directly affect the reliability of the hole metallization quality.

The defects of copper foil include delamination (the copper foil is separated from the substrate), nail head (inner layer burr), drilling dirt (thermal and mechanical adhesion layer), brush (protrusion left on the surface after drilling) , Debris (mechanical adhesion), rough (mechanical adhesion).

Substrate defects include delamination (delamination between substrate layers), voids (cavities left by the reinforcement fibers being torn apart). Debris piles (debris accumulated in the cavity), drilling dirt (thermal and mechanical adhesion layer), loose fibers (unbonded fibers), grooves (stripes on the resin). Rifle (spiral groove line) etc.

Factors affecting the quality of PCB circuit board drilling

1. The printed board is composed of resin, fiberglass cloth, copper foil and other materials, with complex materials. Therefore, impact drilling

There are many processing factors, and a little carelessness in the processing process may directly affect the quality of the hole, and in severe cases, it will cause scrap. Therefore, if an abnormality is found in the drilling over product, the problem must be analyzed in time, and the corresponding process countermeasures must be put forward and corrected in time to produce low-cost, high-quality printed boards.

2. The drilling quality of the circuit board is related to the structure and characteristics of the base material, the performance of the equipment, the working environment, the application of the backing plate cover, the quality of the drill bit and the cutting process conditions and other factors (see the figure below for details). Analyze the specific causes of the quality problems of the boreholes, and analyze the specific conditions of these influencing factors to find out the exact influencing factors, so as to take targeted improvement measures.

3. Some factors that affect the quality of circuit board drilling are mutually restrictive, and sometimes several factors work at the same time to affect the quality. For example, a substrate with a higher glass transition temperature (Tg) and a substrate with a lower glass transition temperature, due to the different brittleness of the substrate, the selection of drilling conditions should be different, for the substrate with a higher glass transition temperature The feed rate of drilling is lower. Therefore, it is necessary to formulate the correct drilling procedure and select the appropriate drilling process before drilling, and have a good understanding of the structural characteristics and physical and chemical properties of the substrate.