JPH06252529A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To cope with high density of an electronic equipment by forming in thin-line the copper circuit pattern of a printed wiring board in a square shape without side etching. CONSTITUTION:A first conductive covering 1 is formed on an insulation substrate with double-sided copper foil and then a first sensitized layer 3 is applied to it. Active rays are applied to the first sensitized layer 3 and then exposure and development are made for forming a resist pattern in reverse printing according to the first sensitized layer 3, a second conductive film 4 is formed on a first conductive film 2 at a part which is not covered with the resist pattern, and then the resist pattern according to the first sensitized layer 3 is peeled off. Then, a second sensitized layer 5 is coated on the first and second conductive films 2 and 4 and the resist pattern is formed in normal printing by exposure and development so that only the second conductive film 4 can be covered, and then the second sensitized layer 5 is peeled off by etching, thus forming a copper circuit pattern 6.

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 printed wiring board having an improved etching resist shape.

[0002]

2. Description of the Related Art In recent years, as the density of electronic devices has increased, printed circuit boards are required to have finer circuit patterns. Conventionally, as a method of manufacturing a printed wiring board,
A tenting method or a pattern plating method is known as a representative example. The tenting method is as shown in FIG.
As shown in FIG. 3A, after forming the first conductive coating film 2 on the insulating substrate 1 with a copper foil having a thickness of 9 to 12 μm on both surfaces, as shown in FIG. A second conductive coating 4 is further formed on the coating 2. Then, FIG. 3 (c)
As shown in FIG. 5, a photosensitive film having a film thickness of 50 μm or a film thickness of 10 to 2 is formed as the photosensitive layer 7 on the second conductive film 4.
A 0 μm electrodeposition resist is formed on the entire surface. Then, FIG.
As shown in (d), the resist pattern of the photosensitive layer 7 is formed by irradiating with actinic rays for exposure and development. Then
As shown in FIG. 3E, the copper circuit pattern 6 is obtained by etching a portion not covered by the resist pattern with a cupric chloride etching solution or a ferric chloride etching solution. Finally, as shown in FIGS. 3 (f) and (g),
The resist pattern of the photosensitive layer 7 is peeled off to obtain a printed wiring board having a copper circuit pattern 6 composed of the first conductive coating 2 and the second conductive coating 4.

In the pattern plating method, first, as shown in FIG.
As shown in (a), after forming the first conductive coating film 2 on the insulating substrate 1 with a copper foil having a thickness of 9 to 12 μm on both sides, as shown in FIG. Film thickness 5 on coating 2
After forming a pattern of the photosensitive layer 7 by coating a photosensitive film of 0 μm, it is exposed to actinic rays and exposed and developed to form a resist pattern of the photosensitive layer 7 of the reverse plate. Next, FIG.
As shown in FIG. 4C, after forming the second conductive film 4 on the first conductive film 2 which is not covered with the resist pattern of the photosensitive layer 7, as shown in FIG. Further, a protective metal film 8 made of solder is formed as an etching resist on the second conductive film 4. Next, as shown in FIG. 4 (e), after the photosensitive layer 7 is peeled off, as shown in FIG. 4 (f), the first exposed layer is exposed with a cupric chloride etching solution or the like.
The conductive coating 2 is removed by etching. Finally, as shown in FIGS. 4G and 4H, the protective metal film 8 is peeled off to have a copper circuit pattern 6 composed of the first conductive film 2 and the second conductive film 4. Get the printed wiring board.

In the conventional tenting method and pattern plating method described above, as shown in FIGS. 3 (g) and 4 (h), the side etching amount on one side reaches about 15 μm, and the circuit pattern is thinned. Had been an obstacle.

[0005]

According to the conventional method for manufacturing a printed wiring board by the tenting method or the pattern plating method, the side etching amount of the circuit pattern is large, so that it is difficult to make the circuit pattern thin and the electronic device is expensive. There is a problem that it cannot cope with the densification.

It is an object of the present invention to provide a method for manufacturing a printed wiring board which has a small amount of side etching of a circuit pattern, enables the circuit pattern to be thinned, and can cope with high density of electronic equipment.

[0007]

A method for manufacturing a printed wiring board according to a first aspect of the present invention comprises a step of forming a first conductive coating by perforating a predetermined position of an insulating substrate with a double-sided copper foil, and the first conductive film. Forming a resist pattern by the first photosensitive layer by reverse printing by coating the first photosensitive layer on the conductive film, irradiating with actinic rays, exposing and developing, and a portion not covered by the resist pattern. Forming a second conductive film on the first conductive film, and then removing the resist pattern; and a second photosensitive film on the first conductive film and the second conductive film. A step of coating a layer, a step of exposing and developing to form a resist pattern of the second photosensitive layer so as to cover only the second conductive film, and a step of exposing the exposed first conductive film. The etching step and the second photosensitive layer Stripping the resist pattern and forming a copper circuit pattern.

A method of manufacturing a printed wiring board according to a second aspect of the present invention comprises a step of forming a first conductive coating on a double-sided copper foil-insulated insulating substrate at a predetermined position and forming a first conductive coating on the first conductive coating. A step of forming a resist pattern on the first photosensitive layer by reverse printing by exposing the first photosensitive layer to actinic rays, exposing and developing, and a portion of the first conductive film not covered by the resist pattern. Of forming a second conductive film on the conductive film and then coating the second photosensitive layer on the second conductive film, and exposing to slightly thicker than the width of the pattern of the second photosensitive layer. A step of developing to form a resist pattern by the first photosensitive layer and the second photosensitive layer in an original form; a step of etching the first conductive film; the first photosensitive layer and the second Remove the resist pattern from the photosensitive layer of the copper circuit pattern And forming.

[0009]

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

1 (a) to 1 (h) are sectional views showing the first embodiment of the present invention in the order of steps, and FIG. 1 (i) is shown in FIG.
(H) It is an expanded sectional view of A part. In the first embodiment, first, as shown in FIG. 1A, the thickness is 9-12 μm on both surfaces.
After making a hole with a diameter of 0.4 mm by drilling on the insulating substrate 1 with m copper foil, electroless copper plating is applied to about 2
A first conductive film 2 having a thickness of μm is formed. Then
As shown in FIG. 1B, a first photosensitive layer 3 of a dry film having a film thickness of 50 μm is laminated as a plating resist on the first conductive film 2 and exposed and developed to form pads and circuit patterns. The pattern of the first photosensitive layer 3 is reverse-printed on a portion other than the region to be formed.

Then, as shown in FIG. 1C, electrolytic copper plating solution (CuSO ₄ : 85 g / l, H ₂ SO ₄ : 19)
Current density of 1.5 A / dm in 0 g / l, brightener: small amount)
Immerse in ^{2 for} about 1 hour, or electroless copper plating solution (Cu
_{SO 4: 10g / l, 37} % HCOH: 3~4ml /
1), EDTA, NaOH) for about 10 hours, so that the first unexposed portion of the first photosensitive layer 3
A pattern of the second conductive coating film 4 is formed on the conductive coating film 2 in a thickness of about 20 μm. Next, as shown in FIG. 1 (d), after the pattern of the first photosensitive layer 3 is peeled off with methylene chloride, as shown in FIG. 1 (e), the first conductive film 2 and the second conductive film 2 are removed. A photosensitive dry film having a film thickness of 50 μm or a film thickness of 1 as the second photosensitive layer 5 on the conductive film 4.
An electrodeposition resist of 0 to 20 μm is formed by vacuum lamination or electrodeposition.

Next, as shown in FIG. 1F, the second photosensitive layer 5 is exposed and developed so as to be slightly thicker than the width of the pattern of the second conductive film 4 to form the second photosensitive layer 5. A resist pattern is formed in the relief printing. Then, as shown in FIG. 1 (g), an etching solution of cupric chloride (Cu ²⁺ : 80 to 14
0 g / l, Cu ⁺ : 5 to 20 g / l, Na ⁺ : 0 to 20
g / l, HCl: 50-100 g / l), after etching the first conductive film 2 not covered by the second photosensitive layer 5, as shown in FIG. The photosensitive layer 5 was peeled off to obtain a printed wiring board according to the first embodiment having a copper circuit pattern 6 with a small amount of side etching.

In the copper circuit pattern 6 of the printed wiring board thus obtained, since the second conductive film 4 is covered with the second photosensitive layer 5, as shown in FIG. 1 (i). ,
There was no side etching of the second conductive coating 4, and the shape was a rectangle that could be thinned.

2 (a) to 2 (g) are sectional views showing a second embodiment of the present invention in the order of steps, and FIG. 2 (h) is shown in FIG.
(G) It is an expanded sectional view of a B part. In the second embodiment, first, as shown in FIG. 2A, the thickness is 9-12 μm on both sides.
After making a hole with a diameter of 0.4 mm by drilling on the insulating substrate 1 with m copper foil, electroless copper plating is applied to about 2
A first conductive film 2 having a thickness of μm is formed. Then
As shown in FIG. 2B, a first photosensitive layer (positive type) 3 having a film thickness of 50 μm is laminated as a plating resist on the first conductive film 2 and exposed and developed to perform pad and circuit patterns. The pattern of the first photosensitive layer 3 is reverse-printed on a portion other than the region for forming.

Then, as shown in FIG. 2 (c), an electrolytic copper plating solution (CuSO ₄ : 85 g / l, H ₂ SO ₄ : 19)
Electric density of 1.5 A / dm in 0 g / l, brightener: small amount)
Immerse in ^{2 for} about 1 hour, or electroless copper plating solution (Cu
_{SO 4: 10g / l, 37} % HCHO: 3~4ml /
1), EDTA, NaOH) for about 10 hours, so that the first unexposed portion of the first photosensitive layer 3
A pattern of the second conductive coating film 4 is formed on the conductive coating film 2 in a thickness of about 20 μm. Next, as shown in FIG. 2D, a film thickness of 6 to 8 is formed as a second photosensitive layer (positive type) 5 on the second conductive film 4 without removing the first photosensitive layer 3.
A μm electrodeposition resist is formed. Then, as shown in FIG. 2E, exposure and development are performed to be slightly thicker than the width of the pattern of the second photosensitive layer 5 to form a resist pattern of the first photosensitive layer and the second photosensitive layer in the relief printing. .

Then, as shown in FIG. 2 (f), a cupric chloride etching solution (Cu ²⁺ : 80 to 140 g / l, Cu
⁺ : 5 to 20 g / l, Na ⁺ : 0 to 20 g / l, HC
1: 50 to 100 g / l), the first conductive film 2 which is not covered with the first photosensitive layer (positive type) 3 and the second photosensitive layer (positive type) 5 is etched, and then FIG. As shown in (g), the printed wiring board according to the second embodiment having the side and the copper circuit pattern 6 with a small etching amount by peeling off the resist pattern formed by the first photosensitive layer 3 and the second photosensitive layer 5 is formed. Obtained.

In the copper circuit pattern 6 of the printed wiring board thus obtained, the second conductive film 4 was covered with the first photosensitive layer 3 and the second photosensitive layer 5, so that FIG.
As shown in (h), there was no side etching of the second conductive film 4 like the same circuit pattern of the first embodiment, and it was a rectangular shape capable of thinning.

[0018]

As described above, the present invention eliminates the side etching amount of the copper circuit pattern by coating the etching resist for forming the copper circuit pattern also on the side of the conductive film which becomes the copper circuit pattern. Since it can be formed in a shape close to, it has an effect that it can be made finer and can cope with higher density of electronic devices.

[Brief description of drawings]

1A to 1H are cross-sectional views showing the first embodiment of the present invention in the order of steps for explaining the first embodiment of the present invention, and FIG.
It is an expanded sectional view of a part.

2 (a) to 2 (g) are sectional views showing the second embodiment of the present invention in the order of steps, and FIG. 2 (h) is FIG. 2 (g) B.
It is an expanded sectional view of a part.

3 (a) to 3 (f) are cross-sectional views showing the order of steps for explaining an example of a conventional method for manufacturing a printed wiring board;
FIG. 3G is an enlarged cross-sectional view of the C portion in FIG.

4A to 4G are cross-sectional views showing another example of the conventional method for manufacturing a printed wiring board in the order of steps,
FIG. 4H is an enlarged cross-sectional view of the D part in FIG.

[Explanation of symbols]

 1 Insulating Substrate 2 First Conductive Film 3 First Photosensitive Layer 4 Second Conductive Film 5 Second Photosensitive Layer 6 Copper Circuit Pattern 7 Photosensitive Layer 8 Protective Metal Film

Claims (4)

[Claims] 1. A step of forming a first conductive coating by perforating the insulating substrate with double-sided copper foil at a predetermined position, and coating the first photosensitive layer on the first conductive coating with an actinic ray. A step of irradiating, exposing and developing to form a resist pattern by the first photosensitive layer in a reverse plate; and forming a second conductive film on the first conductive film in a portion not covered by the resist pattern. After forming, the step of peeling off the resist pattern, the step of coating a second photosensitive layer on the first conductive coating and the second conductive coating, and the second conductive coating by exposing and developing. Forming a resist pattern of the second photosensitive layer so as to cover only the conductive coating, etching the exposed first conductive coating, and
And removing the resist pattern formed by the photosensitive layer to form a copper circuit pattern. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the step of coating the second photosensitive layer on the second conductive film includes a step of laminating in a vacuum. 3. A step of forming a first conductive coating by perforating the insulating substrate with double-sided copper foil at a predetermined position, and coating the first photosensitive layer on the first conductive coating with an actinic ray. A step of irradiating, exposing and developing to form a resist pattern by the first photosensitive layer in a reverse plate, and forming a second conductive film on the first conductive film in a portion not covered by the resist pattern. After the formation, a step of coating the second photosensitive layer with a second photosensitive layer, and a step of exposing and developing a layer slightly thicker than the width of the pattern of the second photosensitive layer to form the first photosensitive layer. A step of forming a resist pattern by the second photosensitive layer in an original form; a step of etching the first conductive film;
A method of manufacturing a printed wiring board, comprising the steps of peeling a resist pattern formed by the first photosensitive layer and the second photosensitive layer to form a copper circuit pattern. 4. The method for manufacturing a printed wiring board according to claim 3, wherein the first and second photosensitive layers are photodegradable photosensitive layers.