JPH05110226A - Manufacture of printed board - Google Patents

Abstract

PURPOSE:To form as fine pattern at low cost on a conductive layer of a printed board by using an ordinary etching resist. CONSTITUTION:In a manufacturing method of a printed board including an etching process where a pattern of an etching resist 3 is provided on a conductive layer in a thick shape than the pattern of a conductive layer to be formed in order to form a conductive layer of a printed board in a prescribed pattern, the corner part A of the pattern 3a is thicker than the other parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a printed circuit board, which enables formation of a fine pattern on a conductive layer of the printed circuit board.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a pattern on a conductive layer of a printed circuit board, a conductive layer such as copper foil is formed on the entire surface of the board, and an etching resist is formed in a predetermined pattern on the conductive layer. Then, a method of forming a conductive pattern in a predetermined pattern by removing the conductive layer in a portion not masked by the etching resist by etching with an etching solution is used.

In this case, since the etching of the conductive layer by the etching solution is isotropic etching, it progresses not only in the depth direction of the conductive layer but also in the width direction of the pattern, so-called side etching occurs. Therefore, the pattern of the etching resist formed on the conductive layer is formed to be thicker than the pattern of the conductive layer to be formed.

For example, as shown in FIG.
A copper foil 2 having a thickness of 50 μm is laminated on the base material 1, and the copper foil 2
When a pattern 3 of an etching resist is provided on the upper side and is etched with an etching solution such as an aqueous solution of ferric chloride or an aqueous solution of cupric chloride, side etching proceeds on the copper foil 2 as shown in FIG. Then, the pattern is formed with a width that is normally 50 to 100 μm narrower than the pattern 3 of the etching resist. Therefore, in order to form the conductive layer in a predetermined pattern, the width of the etching resist pattern 3 is set to be 50 to 100 μm smaller than that of the conductive layer pattern to be formed.
It is made to be fat by about m.

Further, such side etching of the conductive layer progresses particularly greatly at the pattern corner portion due to the high efficiency of replacement of the etching solution, and reaches about 100 to 200 μm, which is twice as much as the portion other than the corner portion. Therefore, as shown in FIG. 6A, if the pattern width of the etching resist is widened in the same manner as the other portions, the etching resist is patterned as shown in FIG. 6B. Side etching greatly progresses in the pattern corner portion, and the pattern width of the conductive layer 2 in that portion becomes narrower than a predetermined size, resulting in a defective product. Therefore, when forming a pattern having such a corner portion on the conductive layer, the pattern width of the etching resist is thickened by about 100 to 200 μm in accordance with the side etching of the corner portion.

[0006]

On the other hand, with the recent increase in the density of wiring, there is a strong demand for finer patterns in the conductive layer, and the pattern gap tends to become narrower. However, when the pattern width of the etching resist is thickened in accordance with the side etching of the pattern corner portion, it becomes impossible to resolve a narrow pattern gap, and as a result, a fine pattern cannot be formed in the conductive layer. Has occurred.

For example, assuming that the side etching of the pattern corner portion progresses by 100 μm, the conductive layer has a thickness of 150.
In order to form a pattern of μm pattern / 150 μm gap, the pattern of the etching resist must be formed to 250 μm pattern / 50 μm gap.
It is not possible to resolve a pattern gap of 0 μm.

On the other hand, if a very special etching resist such as an electrodeposition resist is used, a pattern gap having a width of 50 μm can be resolved, but the manufacturing cost becomes very high.

The present invention is intended to solve the problems of the prior art as described above, and the pattern width and the pattern gap are each 15 in the conductive layer of the printed circuit board.
It is an object of the present invention to make it possible to form a fine pattern of 0 μm or less at low cost by using an ordinary etching resist.

[0010]

The present inventor has found that the above object is to form the pattern of the etching resist largely only in the pattern corner portions and to form the other portions by a usual thickening method other than the corner portions. They have found that they can be achieved, and have completed the present invention.

That is, according to the present invention, in order to form a conductive layer of a printed circuit board in a predetermined pattern, an etching resist pattern is formed on the conductive layer in a shape thicker than the pattern of the conductive layer to be formed. Provided is a method for manufacturing a printed circuit board, which comprises a step of etching, wherein the amount of thickening of a pattern of an etching resist is made larger at a pattern corner portion than at a portion other than the corner portion.

As described above, in the manufacturing method of the present invention, the pattern of the etching resist is greatly thickened at the corners, but in this case, it is not necessary to thicken the pattern at all the corners of each wiring pattern. When connecting multiple individual wiring patterns with corners,
Since the exchange efficiency of the etching liquid is particularly high outside the corner portion of the overall pattern and the side etching greatly progresses, the pattern may be thickened only at the corner portion of the outer pattern. For example, as shown in FIG. 1, an L-shaped pattern 3 having a corner angle θ of 90 °
When a, 3b, and 3c are provided in series, the pattern may be thickened only at the corners of the outer pattern 3a.
The corner angle of such a corner portion is usually 90 degrees.
It is ± 30 °.

When thickening the pattern of the etching resist at the corners, the thickening method can be various shapes as long as the conductive layer has a predetermined pattern width after etching. For example, the pattern may be thickened by forming the round land A like the pattern 3a in FIG. 1, and although not shown, an elliptical land, a square land, a polygonal land, or the like may be formed. Also,
As in the pattern 3a of FIG. 2, the pattern may be thickened outward at the corner portion. Alternatively, the pattern 3a in FIG.
As described above, the convex portion B or the convex portion C may be formed so as to extend the linear pattern at the corner portion. In this case, the convex portion B and the convex portion C may form either one or both. Further, in general, the shape of the corner portion of the pattern is L-shaped as shown in FIG. 1 to FIG. 3 and is also rounded as shown in FIG. 4, in which case the pattern of FIG. 3a, the outer pattern 3
The outer curvature R1 of the corner portion of a may be smaller than the inner curvature R2.

In the method for manufacturing a printed board according to the present invention, the steps other than the step of forming a pattern on the conductive layer can be performed in the same manner as the conventional method. The method of the present invention can also be applied to the case of manufacturing a multilayer substrate having a conductive layer having a multilayer structure.

[0015]

In the method of manufacturing a printed circuit board according to the present invention, since the pattern of the etching resist is greatly thickened at the pattern corner portion, even if the side etching greatly advances with respect to the conductive layer at the pattern corner portion during etching, the conductive layer Can be formed with a predetermined pattern width.

Further, the pattern of the etching resist is thickened only at the corners thereof, and the degree of thickening of the etching resist is reduced in other parts of the pattern, so that a fine pattern can be formed. Become.

[0017]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 In order to manufacture a printed circuit board having a pattern / gap rule of 150 μm / 150 μm, a thickness on the substrate of 50 μm
A normal etching resist was formed on the copper foil of No. 2 with a pattern of 200 μm pattern / 100 μm gap in the straight part of the pattern, and a circular land was formed in the corner part so as to protrude to the outside by 50 μm at the maximum as shown in FIG.

Then, etching was carried out using an aqueous ferric chloride solution as an etching solution. As a result, the pattern of the conductive layer obtained was 150 μm pattern / 150 μm gap except at the corners, and 150 μm at the corners.
m pattern was secured.

Example 2 A printed circuit board was manufactured in the same manner as in Example 1 except that the corners of the etching resist pattern were formed wider by 50 μm on the outside as shown in FIG. as a result,
The pattern of the obtained conductive layer is 150μ except for the corners.
m pattern / 150 μm gap, and a 150 μm pattern was secured at the corners.

Example 3 A printed circuit board was manufactured in the same manner as in Example 1 except that the corner portion of the pattern of the etching resist was formed by extending the linear portion of the pattern by 100 μm to the outside as shown in FIG. As a result, the pattern of the obtained conductive layer was 150 μm pattern / 150 μm gap except the corner portion, and the extended pattern was 30 μm at the corner portion.
Although it remained about 15 times, the pattern width of the conductive layer was 15
A 0 μm pattern was secured.

Example 4 As shown in FIG. 4, the corner portion of the pattern of the etching resist has a curvature R1 on the outer side of the pattern 3a of 100 μm.
A printed circuit board was manufactured in the same manner as in Example 1 except that the inner curvature R2 was 200 μm. As a result, the pattern of the obtained conductive layer was 150 μm pattern / 150 μm gap except the corner portion, and the 150 μm pattern was secured even in the corner portion.

[0023]

According to the method of manufacturing a printed circuit board of the present invention, it is possible to inexpensively form a fine pattern on the conductive layer of the printed circuit board by using an ordinary etching resist.

[Brief description of drawings]

FIG. 1 is a plan view of a substrate on which an etching resist is patterned according to the method of the present invention.

FIG. 2 is a plan view of a substrate on which an etching resist is patterned according to the method of the present invention.

FIG. 3 is a plan view of a substrate on which an etching resist is patterned according to the method of the present invention.

FIG. 4 is a plan view of a substrate on which an etching resist is patterned according to the method of the present invention.

FIG. 5 is a cross-sectional view of a substrate in which an etching resist is patterned on a conductive layer before and after etching.

FIG. 6 is a plan view of a substrate on which an etching resist is patterned on a conductive layer by a conventional method before etching and a plan view of a pattern of a conductive layer after etching.

[Explanation of Codes] 1 Base Material 2 Copper Foil 3 Etching Resist 3a, 3b, 3c Etching Resist Pattern A, B, C Thick Etching Resist Corner Pattern

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motoki Urashima 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (1)

[Claims] 1. A step of forming an etching resist pattern on the conductive layer in a shape thicker than the pattern of the conductive layer to be formed in order to form the conductive layer of the printed circuit board in a predetermined pattern. A method of manufacturing a printed circuit board, including: a method of manufacturing a printed circuit board, wherein an amount of thickening a pattern of an etching resist is larger at a pattern corner portion than at a portion other than the corner portion.