Printed circuit board manufacturing method

Abstract

The invention proposes a manufacturing method of a printed circuit board in which primarily, flexibility and flexuosity are excellent, secondarily, lightweightness and ultrathinning can be realized and densification and microfabrication can be also realized, thirdly, processes are more simplified to reduce a cost, and fourthly, accuracy or the like is improved. In the method, a plurality of through holes 5 are first provided, and conductive treatment is performed on internal sides of the holes 5 in a substrate 3 in which a copper foil 2 is each attached to both sides of an insulating material 1. Next, after one side of the substrate 3 is covered with a photosensitive dry film 16 provided with a masking outer layer 17, a developer is impregnated in the holes 5 from an opposite side, thereby developing the film 16 as a plating resist. Thereafter, the film 16 is cured by exposure, the layer 17 is next removed, and electrolytic copper plating 6 is performed on internal sides of the holes 5 or the like. A circuit pattern 7 is formed after the film 16 is removed.

Description

technical field [0001] The present invention relates to a method of manufacturing a printed wiring board. That is, it relates to a method of manufacturing a printed wiring board in which circuit patterns are formed on both surfaces of an insulating material. Background technique [0002] Printed circuit boards, such as flexible printed circuit boards with flexibility and flexibility, have made remarkable progress in high precision, high performance, ultra-thinning, and lightweight, and the high-density and fine-grained circuit patterns formed Significantly. [0003] Furthermore, the printed wiring board is formed with a plurality of through holes which are fine through holes for connecting circuit patterns on both sides and for mounting semiconductor components and the like. In addition, in the manufacturing process of the printed wiring board, the whole board plating method and the button plating method (button plating) are typically used to manufacture such through-holes...

AI Technical Summary

Problems solved by technology

[0017] Therefore, when the printed wiring board A manufactured by this type of whole board plating method is used, for example, Figure 5 The bent wiring part 10 shown in the schematic plan view of

Moreover, this problem is particularly pronounced for flexible printed wiring boards

[0018] Second, in the manufacturing method of the printed wiring board A performed by the whole board plating method, there are also problems pointed out in terms of the weight and thickness of the printed wiring board A produced, and the high density of the circuit pattern 7 Minaturization and miniaturization have also been pointed out to be problematic

In this way, it has been pointed out that there is a problem that the weight increases and the thickness also increases, which is contrary to the progress of light weight and ultra-thin substrates.

[0020] In addition, it was pointed out that when the circuit pattern 7 leading to both sides is formed in the final process, the electroplated copper 6 formed on the outer surface of the copper foil 2 of the base material 3 becomes an obstacle such as etching, and it is difficult to form a high-density miniaturization. problem with circuit diagram 7

[0021] Third, in the manufacturing method of the printed wiring board B by the button plating method, the manufacturing process is long and complicated and the yield is low, and it is pointed out that there is a problem in terms of cost

However, this button plating method is complicated and cumbersome, and the yield is low, and it is also pointed out that there is a big problem in terms of cost

[0025] Fourth, in the manufacturing method of the printed wiring board B performed by the button plating method, it is also pointed out that there are problems in the positional accuracy of the copper plating 6 of the through hole 4 in the manufactured printed wiring board.

[0026] That is, in the button plating method, as described in the above-mentioned third point, the positions of the through-holes 5 of the base material 3 and the photomask 9 are aligned, but a positional deviation easily occurs between the two.

That is, the position alignment is mostly carried out by visual operation, and at the same time, due to the expansion and contraction of the base material 3 and the photolithography mask plate 9, it is not easy to accurately align the positions.

[0027] Here, it has been pointed out that the printed wiring board B manufactured by the button plating method has difficulty in the positional accuracy of the copper plating 6 leading to the vicinity of the through hole 5, so it is not suitable for a substrate whose high-precision improvement is remarkable.

[0028] Again, the origin of such positional accuracy problems is, for example, image 3 As shown in the plan explanatory diagram of (2), it is difficult to miniaturize the button part C, which is the electroplated copper 6 formed in the shape of a button on the periphery of the opening part of the through hole 4, and the button part C must have a thickness of 0.2 mm anyway. larger diameter

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