Laminar structure of flexible and rigid PCBs less than four in layer number

Abstract

The invention discloses a laminar structure of flexible and rigid PCBs less than four in layer number. The laminar structure comprises flexible inner layer core boards, single-side FR4 copper-clad plates, pure gum and covering films. According to the laminar structure, the flexible inner layer core boards serve as centers, the upper side and the lower side of each flexible inner layer core board are each sequentially provided with the corresponding single-side FR4 copper-clad plate and the corresponding pure gum from outside to inside, and the covering films are only arranged on the upper side and the lower side of the outer edge part of each flexible inner layer core board and extend inwards by a certain distance. The laminar structure has the advantages that after the covering films, at flexible PCBs, of rigid PCBs are removed, the fretting rates of liquid medicine are basically identical during gum residue removal, and the problem of hole copper faultage is solved; in the lamination process, the pure gum is injected to the spaces between lines, the thicknesses of pure gum layers between inner layer copper sides and FR4 decrease, the drilling pollution probability is reduced during drilling, and the problem of plating nodules is solved. The defects are solved, so that the yield of products is greatly increased, raw materials are saved, production cost is lowered, and production efficacy is improved.

Description

technical field [0001] The invention relates to the field of circuit board production, in particular to a laminated structure of a soft-hard board with less than four layers. Background technique [0002] In the production of the existing four-layer or less (including four-layer) soft-rigid board, the specific lamination structure of the product is as follows: figure 1 As shown, the flexible boards are all covered with a cover film, and the soft and hard boards are connected with pure glue as a connecting agent. In actual production, because the thickness of the pure rubber cannot be controlled, such a structure has the following defects: 1. If the thickness of the pure rubber is too thin, the product is prone to voids; 2. If the thickness of the pure rubber is too thick, the subsequent drilling There will be more drill dirt in the cavity, and copper nodules will be formed in the cavity. In addition, in the subsequent desmearing process, due to the different corrosion rate...

AI Technical Summary

Problems solved by technology

In actual production, because the thickness of the pure rubber cannot be controlled, such a structure has the following defects: 1. If the thickness of the pure rubber is too thin, the product is prone to voids; 2. If the thickness of the pure rubber is too thick, the subsequent drilling There will be more drill dirt in the cavity, and copper nodules will be formed in the cavity

[0003] The above problems occur from time to time in production, resulting in unqualified products and affecting the yield of products

Unqualified products can only be discarded, wasting raw materials and reducing production efficiency

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