The number of multi-layer boards is increasing, and the alignment requirements of the inner layers are getting higher and higher. The film will expand and contract under the influence of the temperature and humidity of the workshop environment, and the core board will have the same expansion and contraction when produced, which makes it more difficult to control the alignment accuracy between the inner layers.

　　 This point can be handed over to the rest assured factory, Huaqiu Circuit.

Difficulties in the pressing process

　　 The superposition of multiple core plates and PP (cured plate) is prone to problems such as delamination, sliding plate and steam drum residue during pressing. In the structural design process of the inner layer, factors such as the dielectric thickness between the layers, the glue flow, and the heat resistance of the sheet should be considered, and the corresponding laminated structure should be reasonably designed.

　　 Suggestion: Keep the inner layer of copper evenly spread, and spread the copper in a large area without the same area with the same balance as PAD.

Difficulties in drilling production

　　 Multilayer board is made of high Tg or other special plates, and the roughness of drilling holes of different materials is different, which increases the difficulty of removing the slag in the hole. High-density multi-layer boards have high hole density and low production efficiency, which is easy to break. Between the via holes of different networks, the edge of the hole is too close to cause the CAF effect problem.

　　Recommendation: The hole edge spacing of different networks is ≥0.3mm