JPH05267848A - Manufacture of printed circuit board - Google Patents

Abstract

PURPOSE:To enhance density by irradiating a predetermined through hole with a laser light to remove a predetermined part of either a cured part or an undecomposed part, retaining either the cured part or the undecomposed part, removing photosensitive resin, and forming an etching resist film. CONSTITUTION:A predetermined part of a cured part 15 of a photosensitive resin film 4 in a through hole 5b is removed with a laser light 9 such as an excimer laser. That is, the light 9 having a beam diameter smaller than that of the hole 5b for partial conduction is incident from above a perpendicular direction of the hole 5b. It is reflected by a reflecting plate 10 attached to an end of a reflecting plate support base 11 inserted from under the hole 5b for its part conduction at 90 deg. to an incident angle from an entire circumferential direction to remove a cured part 15 of a wall. The base 11 is vertically moved up and down to selectively remove an unnecessary part of the cured part 15 on the wall of the hole 5b for its partial conduction, an uncured part 4a is removed, and an etching resist film 12 is obtained.

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 is often used for manufacturing a through-hole printed wiring board. According to this method, first, an insulating base material 2 is plated with copper as shown in FIG. The conductor layer 1 including layers and the through holes 5a are formed.

Next, as shown in FIG. 5A, a photosensitive dry film 14 is attached to the surface of the insulating substrate 2.

Next, as shown in FIG. 5 (c), the mask film 7 is brought into contact and a predetermined wiring circuit pattern is irradiated with ultraviolet rays 8a to be baked.

Next, as shown in FIG. 6A, the photosensitive dry film 14 in the unexposed portion is removed with a developing solution to obtain an etching resist film 12.

Next, as shown in FIG. 6B, the exposed conductor layer 1 is removed by etching.

Finally, as shown in FIG. 6C, the etching resist film 12 is peeled and removed to obtain a printed wiring board having the surface wiring circuit 6 and the through holes 5a.

[0008]

However, in the case of this conventional tenting method, an etching resist is used as shown in FIG.
Since it is necessary to protect the inside of the through hole 5a from the etching solution in a tenting state such as the etching resist film 12 shown in (a), the through hole 5a must be completely covered and one through hole 5a has a problem that only one circuit in which both outer layers or inner and outer layers are electrically connected can be formed, and high density cannot be achieved.

An object of the present invention is to provide a method of manufacturing a through hole wiring board having a high density wiring circuit.

[0010]

A method for manufacturing a printed wiring board according to the present invention comprises a step of forming a conductor layer by copper plating on the through holes and the surface of a multilayer copper clad laminate, and electrodeposition on the entire surface of the conductor layer. A step of electrodepositing a photosensitive resin film by a coating method, and exposing a mask film to the surface of the multilayer copper clad laminate to expose the surface wiring portion of the photosensitive resin film and the through hole portion. A step of forming one of the cured portion and the undecomposed portion, and irradiating a laser beam to a predetermined through hole that partially conducts the inside of the hole to form the cured portion and the undecomposed portion. A step of removing a predetermined portion of any one of them, a step of removing the photosensitive resin film leaving any one of the cured portion and the undecomposed portion to form an etching resist film, and exposing The conductive layer is removed by etching Forming a through hole to be electrically connected to the surface wiring circuit said part configured to include a step of removing the etching resist film.

[0011]

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

1 (a) to 2 (c) are sectional views showing the first embodiment of the present invention in the order of steps, and FIG. 3 is a sectional view of a hardened portion of a through hole which is partially conductive in FIG. It is a partial expanded sectional view explaining a removal method.

In the first embodiment, first, as shown in FIG. 1A, a hole is drilled in a multilayer copper-clad laminate 3 composed of a copper foil and an insulating base material 2, and then a predetermined copper plating treatment is performed. Through hole 5a, through hole 5b for partial conduction
And the conductor layer 1 is formed.

Next, as shown in FIG. 1 (b), a negative type photosensitive resin film 4, for example, Sonne EDUV376-510 manufactured by Kansai Paint Co., Ltd., is used on the entire surface of the conductor layer 1 for about 20 minutes.
μm is electrodeposited and dried.

Next, as shown in FIG. 1 (c), light is transmitted through the negative photosensitive resin film 4 to the through holes 5a, the through holes 5b for partial conduction, and the portions corresponding to the surface wiring circuits. A mask film 7 having a pattern is attached and exposed to scattered light ultraviolet rays 8. At this time, the negative photosensitive resin film 4 becomes a cured portion 15 and an uncured portion 4a which are photo-cured by the scattered ultraviolet rays 8.

Next, as shown in FIG. 1 (d), the mask film 7 is removed, and a predetermined portion of the hardened portion 15 of the negative photosensitive resin film 4 in the through hole 5b for partially conducting the laser light 9 is applied to the predetermined portion. For example, excimer laser (wavelength 248n
m, oscillation frequency 10 Hz, irradiation energy 130 mJ)
To remove. As shown in FIG. 3, the method of removing the hardened portion 15 with the laser beam 9 is such that the laser beam 9 having a beam diameter smaller than that of the through hole 5b is made incident from above in the vertical direction of the through hole 5b which is partially conducted. The reflection plate 10 attached to the front end of the reflection plate support 11 inserted from below the through hole 5b for electrical continuity is reflected from the entire circumferential direction by 90 ° with respect to the incident angle, and the hardened portion 15 of the wall surface is formed.
To remove. By moving the reflector support 11 up and down, it is possible to selectively remove the unnecessary portion of the hardened portion 15 on the wall surface of the through hole 5b that is partially conductive.

Next, as shown in FIG. 2A, the uncured portion 4 of the negative photosensitive resin film 4 is coated with a developing solution containing sodium carbonate as a main component.
By removing a, an etching resist film 12 composed of the hardened portion 15 of the negative photosensitive resin film 4 is obtained.

Next, as shown in FIG. 2B, the exposed conductor layer 1
Are etched away with a cupric chloride based etchant. As a result, the through hole 5a, the surface wiring circuit 6,
Only the conductor layer of the through hole 5b that partially conducts remains.

Finally, as shown in FIG. 2 (c), the etching resist film 12 is peeled and removed with a peeling solution containing caustic soda as a main component to form a through hole 5a, a surface wiring circuit 6, and a through hole 5b for partial conduction. The printed wiring board according to the first embodiment thus formed is obtained.

FIGS. 4A to 4D are sectional views showing the second embodiment of the present invention in the order of steps.

In the second embodiment, as shown in FIG. 4 (a), first, as in the first embodiment, after punching holes in the multilayer copper clad laminate 3 composed of the copper foil and the insulating substrate 2. Then, a predetermined copper plating process is performed to form a through hole 5a, a through hole 5b for partial conduction, and a conductor layer 1.

Next, as shown in FIG. 4 (b), a positive type photosensitive resin film 13, for example, P-2000 manufactured by Nippon Paint Co., Ltd., is applied to the entire surface of the conductor layer 1 by electrodeposition to a thickness of about 8 μm. And dry.

Next, as shown in FIG. 4C, a pattern for blocking light to the through hole 5a on the positive type photosensitive resin film 13, a through hole 5b for partial conduction, and a portion corresponding to the surface wiring circuit. A mask film 7a having the above is attached and exposed by scattered light ultraviolet rays 8. At this time, the positive photosensitive resin film 13 becomes a decomposed portion 16 and a non-decomposed portion 16 which are photodecomposed by the scattered light ultraviolet rays 8.

Next, as shown in FIG. 4 (d), the mask film 7a is removed, and the through hole 5b is made partially conductive.
A predetermined portion of the undecomposed portion 13a of the positive photosensitive resin 13 therein is removed by the laser beam 9.

Next, as in the first embodiment, FIG.
The printed wiring board according to the second embodiment having the through hole 5a, the surface wiring circuit 6, and the through hole 5b for partial conduction formed by the treatment of (c) is obtained.

[0026]

As described above, according to the present invention, it is possible to form a through hole having a partially conductive circuit, which was difficult to form by the conventional tenting method, so that the printed wiring board can be densified. Have.

Further, even if a positive photosensitive resin is used, there is an effect that a general hole having a high aspect ratio of 4 or more can be formed.

[Brief description of drawings]

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

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

FIG. 3 is a partial enlarged cross-sectional view illustrating a method of removing a hardened portion of a through hole that is partially conductive in FIG.

4A to 4D are cross-sectional views showing a second embodiment of the present invention in the order of steps.

FIG. 5 is a cross-sectional view showing an example of a tenting method of a conventional printed wiring board manufacturing method, in the order of steps.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor layer 2 Insulating base material 3 Multilayer copper clad laminate 4 Negative photosensitive resin film 4a Unhardened part 5a Through hole 5b Partially conductive through hole 6 Surface wiring circuit 7 Mask film 7a Mask film 8 Scattered light UV light 8a Ultraviolet 9 Laser light 10 Reflector 11 Reflector support 12 Etching resist film 13 Positive photosensitive resin film 13a Undecomposed part 14 Dry film 15 Hardened part 16 Decomposed part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keisuke Okada 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation

Claims (1)

[Claims] 1. A step of forming a conductor layer by copper plating on the through holes and the surface of a multilayer copper clad laminate, a step of electrodepositing a photosensitive resin film on the entire surface of the conductor layer by an electrodeposition coating method, and A mask film is brought into contact with the surface of the multilayer copper-clad laminate to expose it to form either a cured portion or an undecomposed portion at a position corresponding to the surface wiring portion and the through hole portion of the photosensitive resin film. And a step of irradiating a predetermined through hole that partially conducts the inside of the hole with laser light to remove a predetermined portion of one of the cured portion and the undecomposed portion, A step of removing the photosensitive resin film to form an etching resist film leaving either one of the cured portion and the undecomposed portion, and removing the exposed conductor layer by etching to remove the surface wiring circuit and the partial Through hole to connect to And a step of removing the etching resist film, a method of manufacturing a printed wiring board.