JPH06283858A - Manufacture of printed circuit board - Google Patents

Abstract

PURPOSE:To obtain a high density printed circuit board by providing a conductor circuit for partly conducting in a through hole. CONSTITUTION:A high density printed circuit is formed with a through hole 1, a through hole 1b for partly conducting a surface wiring circuit 4, a first conductor layer 2a, a second conductor layer 2b, a third conductor layer 3c and a fourth conductor layer 2d, and a through hole 1c for partly conducting only the layer 2a and the layer 2b.

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, manufacturing of a through-hole printed wiring board (hereinafter referred to as "T / H PWB") is performed with reference to FIG.
As shown in FIG. 4 (b), a tenting method is often used. According to this method, first, as shown in FIG. 3 (a), an insulating layer including a conductor layer 2e including a copper plating layer and a through hole 1a is formed. As shown in FIG. 3B, a photosensitive dry film (hereinafter referred to as a dry film) 8 is attached on the substrate 7, and a desired wiring circuit is formed on the substrate 7 through the mask film 5 as shown in FIG. 3C. Pattern is baked with ultraviolet rays 6a.

Next, as shown in FIG. 3D, the dry film in the unexposed portion is removed with a developing solution to remove the etching resist 3.
a and 3b are obtained.

Further, as shown in FIG. 4 (a), after the exposed conductor layer 2e is removed by etching, finally, as shown in FIG. 4 (b), the etching resists 3a, 3b are peeled off to remove the through hole printed wiring board. Is what you get.

Further, in the hole filling method as shown in FIGS. 5 (a) to 6 (c), as shown in FIG. 5 (a), the insulating substrate 7 having the conductor layer 2e including the copper plating layer and the through hole 1a is formed. As shown in FIG. 5B, the filling ink 9 is filled and cured in the through hole 1a, and the dry film 8 is attached to the surface of the insulating substrate 7 as shown in FIG. 5C.
As described above, a desired wiring pattern is printed with ultraviolet rays 6a through the mask film 5.

Next, as shown in FIG. 6A, the dry film 8 in the unexposed portion is removed with a developing solution to remove the etching resist 3.
a and 3b are obtained.

Further, as shown in FIG. 6B, the exposed conductor layer 2e is removed by etching, and finally, as shown in FIG. 6C, the etching resists 3a and 3b and the hole filling resin 9 are removed.
Is removed to obtain a through-hole printed wiring board.

In this method, instead of the dry film etching resists 3a and 3b, an image formed by screen printing can be used as the etching resist.

[0009]

However, in the case of the tenting method, it is necessary to protect the inside of the through hole 1a from the etching solution by setting the etching resist to a tenting state like the etching resist 3b of FIG. 3 (d). Therefore, it is necessary to completely cover the through hole 1a with the dry film.
However, there is a problem that only one circuit in which both outer layers or inner and outer layers are electrically connected can be formed.

Further, in the hole filling method, after filling the inside of the through hole 1a with the hole filling resin 9 as shown in FIG.
Since the through hole 1a is formed, there is a problem that only one circuit can be formed in one through hole 1a as in the tenting method.

An object of the present invention is to provide a method of manufacturing a printed wiring board having a high-density wiring circuit, which solves the problems of the conventional method.

[0012]

The present invention is a method for manufacturing a printed wiring board having through holes, wherein the through holes and the surface are copper-plated, and then a negative photosensitive resin coating film is electrodeposited on the copper. And a pattern for transmitting light to the through hole portion and the surface wiring portion, and for a predetermined through hole that partially conducts the inside of the hole, light is transmitted onto the through hole with a predetermined mask diameter. A step of contacting a mask film having a pattern for blocking and irradiating scattered light ultraviolet rays, a step of selectively removing the negative photosensitive resin coating film on the unexposed portion by development, and a copper portion exposed by development Is removed with an acidic etching solution, and the remaining negative photosensitive resin coating film is removed, whereby a conductor circuit in which the through holes are partially conducted is obtained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 (a) to 1 (d), 2 (a) and 2 (b)
4A to 4C are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

First, as shown in FIG. 1A, the first conductor layer 2
a, second conductor layer 2b, third conductor layer 2c, fourth conductor layer 2d
After drilling holes in the multi-layer copper-clad laminate 2 having, copper plating treatment is performed.

Next, as shown in FIG. 1B, a negative photosensitive resin coating film 3 is formed on the entire surface of the multilayer copper-clad laminate 2 by electrodeposition coating and then dried.

Next, as shown in FIG. 1 (c), the through holes 1a on the negative photosensitive resin coating film 3 and the surface wiring circuit 4 allow the light to pass therethrough, and the through holes are made to partially conduct electricity in a predetermined manner. For holes 1b and 1c, through holes 1b and 1c
A mask film 5 having a pattern that blocks light with a predetermined mask diameter is brought into contact therewith and exposed to scattered light ultraviolet rays 6.

As for the mask diameter with respect to the hole diameter, the dimensions shown in Table 1 are optimal.

[0019]

[Table 1]

Next, as shown in FIG. 1D, the mask film 5 is removed, and the unexposed portion of the negative photosensitive resin film is adjusted to pH 1
Etching resists 3a and 3b are obtained by removing with a developing solution such as an alkaline aqueous solution of 0 to 13. As the alkaline aqueous solution, Na ₂ CO ₃ , Na ₂ SiO ₃ or the like can be used.

Next, as shown in FIG. 2A, the exposed copper surface is removed with an acidic etching solution. As a result, only the copper inside the through-hole 1a, the surface wiring circuit 4, and the through-holes 1b and 1c that are partially conducted remains.

Next, as shown in FIG. 2 (b), the remaining etching resists 3a and 3b are replaced with 1 to 4% of NaOH or K.
After peeling and removing with an alkaline solution such as OH, a through-hole printing plate in which the through-hole 1a, the surface wiring circuit 4, and the through-holes 1b and 1c for partial conduction are mixed is obtained.

Incidentally, in FIG. 1C, the surface wiring circuit and the mask film 5 for through holes may be divided and separately exposed by scattered light ultraviolet rays. Further, instead of the scattered light UV, it is possible to expose with UV.

[0024]

As is apparent from the above, according to the present invention, it is possible to easily obtain a through hole that is partially conductive, which was difficult to form by the conventional tenting method and hole filling method. This has the effect of increasing the density of the printed wiring board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a process sequence for explaining an embodiment of the present invention.

2A to 2D are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

3A to 3C are cross-sectional views showing an example of a method of manufacturing a printed wiring board by a conventional tenting method in order of steps.

4A to 4D are cross-sectional views showing an example of a method for manufacturing a printed wiring board by a conventional tenting method, in the order of steps.

5A to 5C are cross-sectional views showing an example of a method of manufacturing a printed wiring board by a conventional hole filling method in the order of steps.

FIG. 6 is a cross-sectional view showing the order of steps for explaining an example of a method for manufacturing a printed wiring board by a conventional hole filling method.

[Explanation of symbols]

 1a through hole 1b, 1c through hole for partial conduction 2 multilayer copper clad laminate 2a first conductor layer 2b second conductor layer 2c third conductor layer 2d fourth conductor layer 2e conductor layer 3 negative photosensitive resin coating film 3a, 3b Etching resist 4 Surface wiring circuit 5 Mask film 6 Scattered light UV light 6a UV light 7 Insulating substrate 8 Dry film 9 Hole filling ink

Claims (1)

[Claims] 1. A method of manufacturing a printed wiring board having a through hole, wherein the through hole and the surface are plated with copper, and a negative photosensitive resin coating film is electrodeposited on the copper, and the through hole portion is formed. And a mask having a pattern for transmitting light to the surface wiring portion and a pattern for blocking light with a predetermined mask diameter on the through hole for a predetermined through hole that partially conducts the inside of the hole. A step of contacting the film and irradiating scattered light ultraviolet rays, a step of selectively removing the negative photosensitive resin coating film in the unexposed portion by development, and a step of removing the copper portion exposed by development with an acidic etching solution And a step of removing the remaining negative-type photosensitive resin coating film, to obtain a conductor circuit in which a through hole is partially conducted. Build method.