Flexible multi-layer circuit board and its producing method

Abstract

The invention discloses a multi-layer flexible wiring board and manufacturing method therefor. The multi-layer flexible wiring board has at least three layers, which is characterized in that the wiring board comprises blind holes which only penetrate part of layer wiring boards and through holes penetrate all layer wiring boards. The invention adopts blind holes and through holes to connect layer by layer of the wiring board, the blind holes only need to drill through part of wiring boards, thereby wiring boards which are not be drilled through increase usable area, not all holes adopt perforated method, aligned deviation ratio between each layer is reduced, the number of joints is reduced, thereby reducing derivtion probability of short curcuits and open curcuits.

Description

technical field [0001] The invention relates to a flexible printed circuit board, more specifically to a flexible multilayer circuit board and a manufacturing method thereof. Background technique [0002] Flexible printed circuit boards are developing toward high density, and the structure of multilayer circuit boards is the most commonly used type. As shown in FIG. 9 , it is composed of a plurality of insulating layers 700-710 stacked up and down in sequence and inner layer copper foils 900-905 located therebetween. Each layer of material is combined with semi-cured glue as an adhesive and pressed together, and the layers of copper foil are not connected. Therefore, in order to connect some or specific parts of the lines of each layer, it is necessary to form the through hole H2 by drilling, and then go through the step of electroplating the through hole to make the inner wall surface of the through hole H2 and the surface of the flexible multilayer circuit board An elect...

AI Technical Summary

Problems solved by technology

[0003] It can be seen from the above-mentioned connection mode between the lines of each layer of the existing flexible multilayer circuit board, that is, the connection lines between the layers must be connected in the shape of "匚" as mentioned above, not only the circuit layout is complicated, but also the connection between the layers It needs to be completed by through holes that take up a lot of space, but not every through hole on each layer of circuit board plays a role in connecting lines. For example, a certain through hole may only play the role of connecting three layers of circuit boards, while the fourth The corresponding holes of the circuit board after the layer have no effect, and these holes occupy the surface area of ​​the circuit board, causing most of the surface area of ​​the flexible multilayer circuit board to be occupied by through holes, so that the flexible multilayer circuit board The usable area is greatly reduced and cannot meet the requirements of higher line density

In addition, the materials of each layer adopt a superimposed design. If there is a deviation in the alignment accuracy between the layers, the through holes will not be aligned, resulting in short circuits or open circuits. Since all the holes between the connecting layers are If it penetrates, it will increase the deviation rate of alignment between layers, increase the number of contacts, and thus increase the probability of derivative short circuit or open circuit, which has a decisive impact on the stability of flexible multilayer circuit boards.

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