JPH0613752A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To realize wiring circuits to connect arbitrary layers to each other through holes to increase the mounting density of a printed wiring board. CONSTITUTION:A wiring circuit 4a and a wiring circuit 4b, for electrically connecting the layers of a printed wiring board to each other are selectively formed partially or entirely on the whole surfaces of the interiors of a through holes 1a to 1c. In the case where the wiring circuit is formed on the whole surface of the interiors of the through holes, the whole surfaces of the interiors of the through holes are shielded from light at the time of an exposure and the wiring circuit 4a is left intact on the whole surfaces of the interior of the holes 1a. In the case where the wiring circuits are respectively formed partially on the whole surfaces of the interiors of the through holes, the interiors of the holes 1b and 1c are locally exposed and the necessary wiring circuits 4b only are left when etched. Thereby, only the inner layers of the board or only the inner and outer layers only of the board can be electrically connected to each other by the local circuits 4b on the whole surfaces of the interiors of the holes 1b and 1c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a through-hole printed wiring board having a high-density wiring circuit.

[0002]

2. Description of the Related Art Generally, a tenting method as shown in FIGS. 7 to 12 is often used for manufacturing a through-hole printed wiring board. According to this method, a conductor layer 2e including a copper plating layer and a through hole 1a are formed on an insulating substrate 7 as shown in FIG. 7, and a photosensitive dry film (hereinafter, referred to as a photosensitive dry film) is formed on the substrate 7 as shown in FIG. A dry film) 8 is applied, and a desired wiring circuit pattern is printed with ultraviolet rays 6a through the mask film 5 as shown in FIG.

Next, the dry film 8 in the unexposed portion is removed with a developing solution, and the etching resist 3a, shown in FIG.
You get 3b.

Further, the exposed conductor layer 2e is removed by etching to obtain the state shown in FIG. 11, and then the etching resists 3a and 3b are removed by stripping as shown in FIG.
A through-hole printed wiring board having a surface wiring 4 made of e and a through-hole 1a is obtained.

In the hole filling method shown in FIGS. 13 to 19, the conductor layer 2 including the copper plating layer is formed on the insulating substrate 7 shown in FIG.
e and the through hole 1a are formed, the through hole 1a of the substrate 7 is filled with the hole-filling resin 9 as shown in FIG. 14 and hardened, and the dry film 8 is attached to the substrate surface. A desired wiring circuit pattern is printed with ultraviolet rays 6a through the film 5.

Next, the dry film in the unexposed portion is removed with a developing solution to obtain etching resists 3a and 3b shown in FIG.

Further, the exposed conductor layer 2e is removed by etching to obtain the state shown in FIG.
To obtain a printed wiring board having through holes. In this method, an image formed by screen printing may be used as an etching resist instead of the etching resists 3a and 3b formed of a dry film.

[0008]

However, in the case of the tenting method, it is necessary to protect the inside of the through hole from the etching liquid by setting the etching resist in a tenting state like the etching resist 3b of FIG. 1a must be completely covered with a dry film, the conductor layer 2e is left as it is on the entire inner circumference of the through hole 1a, and lands are provided on both outer layers, so that both outer layers or inner and outer layers are electrically connected in the through hole 1a. There was a problem that only the wiring circuit that was made possible could be formed.

Further, the hole filling method has the same problem as the tenting method because the through hole is formed after the inside of the through hole 1a is filled with the hole filling resin 9 as shown in FIG.

An object of the present invention is to provide a method for manufacturing a printed wiring board, which can easily obtain a wiring circuit in which only the inner layer or only the inner layer and the outer layer are partially conducted in a through hole. is there.

[0011]

In order to achieve the above object, a method for manufacturing a printed wiring board according to the present invention is a printed wiring board having a conductor layer forming step, an electrodeposition coating step, and a wiring circuit forming step. And a conductor layer forming step is a step of forming a conductor layer on the entire inner circumference of a through hole provided in a printed wiring board, and an electrodeposition coating step is a positive type photosensitive layer covering the entire surface of the conductor layer. Is a step of electrodeposition coating a conductive resin coating film, and the wiring circuit forming step is a step of forming a wiring circuit by a conductor layer on the inner surface of the through hole by using a photoetching process. The process of forming a wiring circuit on the entire inner circumference of the through hole is performed by selectively forming the entire circumference or a part thereof on the inner circumference of the through hole. The process of forming a wiring circuit on a part of the inner circumference of the through hole is to locally expose the inside of the through hole and leave a conductor layer necessary for the wiring circuit by etching, and remove unnecessary conductor layers. To remove.

[0012]

According to the present invention, a wiring circuit is selectively formed on the entire surface or a part of the through hole by using a photoetching process.

When a wiring circuit is formed on the entire surface of the through hole, the entire surface of the through hole is shielded from light during exposure.
A process of leaving the conductive layer as it is on the entire inner circumference of the through hole is performed.

When a wiring circuit is formed in a part of the through hole, the through hole is locally exposed to leave a conductor layer necessary for the wiring circuit by etching, and an unnecessary conductor layer is removed. To do.

Therefore, the wiring circuit provided in a part of the through hole partially connects only the inner layer of the printed wiring board or only the inner layer and the outer layer.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are cross-sectional views showing a method of manufacturing a printed wiring board according to an embodiment of the present invention in the order of steps.

In FIG. 1, a through hole 1a is punched in a multilayer copper clad laminate 2 having a first conductor layer 2a, a second conductor layer 2b, a third conductor layer 2c and a fourth conductor layer 2d, and then,
Copper plating is applied to the through holes 1a, 1b, 1c to form the conductor layer 2e.

Next, the conductor layers 2a and 2d on the plate surface of the laminated plate 2
A positive type photosensitive resin coating film 3 is formed on the entire surface of the conductor layer 2e of the through holes 1a, 1b and 1c by electrodeposition coating as shown in FIG. 2, and then dried.

Further, as shown in FIG. 3, the conductor layer 2a to be the surface wiring circuit 4 (see FIG. 6) on the laminated plate 2 and the through hole 1a in which the wiring circuit 4a (see FIG. 6) is provided on the entire inner circumference. A through-hole in which the blocking portion 5a of the mask film 5 completely shields the scattered ultraviolet light 6 from the upper positive photosensitive resin coating film 3 and a wiring circuit 4b (see FIG. 6) is provided in a part of the inner circumference. The coating film 3 on 1b and 1c is locally exposed by transmitting the scattered light ultraviolet rays 6 with a predetermined mask diameter through the transmitting portion 5b of the mask film 5. The optimum mask diameters for the through holes 1b and 1c of the transparent portion 5b are shown in Table 1 below.

[0020]

Next, the mask film 5 is removed, and FIG.
The exposed positive photosensitive resin coating film 3 to pH 1
It is removed with a developing solution such as an alkaline aqueous solution of 0 to 13 to obtain etching resists 3a and 3b. As the alkaline aqueous solution, Na ₂ CO ₃ , Na ₂ SiO ₃ or the like can be used.

Thereafter, as shown in FIG. 5, the resists 3a, 3
Using b as a mask, the conductor layers 2a, 2d, and 2e protruding from the resists 3a and 3b are removed by an acidic etching solution. As a result, the conductor layer 2e remains as it is on the entire inner circumference of the through hole 1a. Also, another through hole 1
Unnecessary conductor layers are removed in parts of b and 1c, and only parts necessary for the wiring circuit remain.

Next remaining etching resists 3a, 3
Strip b with 1-4% alkaline solution such as NaOH or KOH. As a result, the wiring circuit 4a is formed on the entire inner surface of the through hole 1a as shown in FIG. Further, a minimum necessary wiring circuit 4b is formed on a part of the inner circumference of the other through holes 1b and 1c. The surface wiring circuit 4 is formed on the board surface of the printed wiring board.

Incidentally, in FIG. 3, the surface wiring circuit and the mask film 5 for through holes may be divided and separately exposed by scattered light ultraviolet rays. It is also possible to expose with ultraviolet light instead of scattered ultraviolet light.

[0025]

As is apparent from the above, according to the present invention, it is difficult to form wiring by the conventional tenting method and hole filling method, or only the inner layer or the inner layer and the outer layer are partially electrically connected. Through holes having a circuit can be easily obtained, and the printed wiring board can be highly densified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 3 is a cross-sectional view showing a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 4 is a cross-sectional view showing the method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 5 is a cross-sectional view showing a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 6 is a cross-sectional view showing a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 7 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional tenting method in the order of steps.

FIG. 8 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional tenting method in the order of steps.

FIG. 9 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional tenting method in the order of steps.

FIG. 10 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional tenting method in the order of steps.

FIG. 11 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional tenting method in the order of steps.

FIG. 12 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional tenting method in the order of steps.

FIG. 13 is a cross-sectional view showing the method of manufacturing a printed wiring board by the hole filling method in the order of steps.

FIG. 14 is a cross-sectional view showing the method of manufacturing a printed wiring board by the hole filling method in the order of steps.

FIG. 15 is a cross-sectional view showing the method of manufacturing a printed wiring board by the hole filling method in the order of steps.

FIG. 16 is a cross-sectional view showing the method of manufacturing a printed wiring board by the hole filling method in the order of steps.

FIG. 17 is a cross-sectional view showing the method of manufacturing the printed wiring board by the hole filling method in the order of steps.

FIG. 18 is a cross-sectional view showing the method of manufacturing the printed wiring board by the hole filling method in the order of steps.

FIG. 19 is a cross-sectional view showing the method of manufacturing a printed wiring board by the hole filling method in the order of steps.

[Explanation of symbols]

 1a, 1b, 1c through hole 2 multilayer copper clad laminate 2a first conductor layer 2b second conductor layer 2c third conductor layer 2d fourth conductor layer 2e, 2f conductor layer 3 positive photosensitive resin coating film 3a etching resist ( Surface wiring circuit forming part) 3b Etching resist (through hole forming part) 4, 4a, 4b Surface wiring circuit 5 Mask film 5a Mask film blocking part 5b Mask film transmitting part 6 Scattered light UV

Claims (1)

[Claims] 1. A method of manufacturing a printed wiring board, comprising: a conductor layer forming step, an electrodeposition coating step, and a wiring circuit forming step, wherein the conductor layer forming step comprises forming a through hole provided in the printed wiring board. It is a step of forming a conductor layer on the entire inner circumference, the electrodeposition coating step is a step of electrodepositing a positive photosensitive resin coating film on the entire surface of the conductor layer, and the wiring circuit forming step is a photoetching process. It is a process of forming a wiring circuit by a conductor layer on the inner surface of the through hole by using the wiring circuit, which is selectively formed on the entire inner circumference of the through hole or a part thereof. The process of forming the wiring circuit is
During the exposure, the entire inside of the through hole is shielded from light, and the conductor layer is left as it is in the through hole. The process of forming a wiring circuit in a part of the inner periphery of the through hole is
A method for manufacturing a printed wiring board, which comprises locally exposing the inside of a through hole to leave a conductor layer necessary for a wiring circuit by etching and removing an unnecessary conductor layer.