JP2003073844A - Electroless plating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroless plating method which does not need roughening treatment by chemicals, when electroless-plating a resin substrate which incorporates a plating catalyst. SOLUTION: This method is characterized by forming mechanical recesses on the resin substrate which incorporates the plating catalyst, before electroless plating it, and making the recesses have a shape like a wedge or a hole, depths of about 10 μm, and distances among the recesses of about 50 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroless plating method which does not require surface roughening treatment with a chemical when electroless plating is performed on a resin substrate.

[0002]

2. Description of the Related Art Conventionally, when electroless plating is performed on a resin substrate, a plating catalyst is coated on the resin substrate or a surface of the resin substrate kneaded with the plating catalyst is chemically treated in order to cause a plating deposition reaction. Roughening treatment (roughening)
Then, the plating catalyst was exposed on the surface of the resin substrate. After that, the resin substrate subjected to the above treatment was immersed in an electroless plating solution for a predetermined time to form a plating film on the surface of the resin substrate.

[0003]

The conventional electroless plating method has the following problems. (1) When electroless plating is performed by coating a plating catalyst on a resin substrate, the plating catalyst is mainly applied by dipping in a solution containing the plating catalyst. There is almost no selectivity. (2) When electroless plating is performed on a resin substrate in which a plating catalyst is kneaded, a resin layer (skin layer) on the surface of the resin substrate
Is required to expose the plating catalyst,
Surface roughening is usually performed with chemicals. This roughening treatment is difficult with a resin substrate having excellent chemical resistance, and for example, in the case of an epoxy resin substrate, it has been limited to work using a powerful chemical such as Cr sulfuric acid.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to perform electroless plating on a resin substrate mixed with a plating catalyst, which does not require roughening treatment by chemicals. It is to provide a plating method.

[0005]

In the electroless plating method of the present invention, in order to achieve the above object, mechanical recesses are formed on a resin substrate and then electroless plating is performed.

A plating catalyst was kneaded with the resin substrate.

The mechanical recess is wedge-shaped or hole-shaped.

The wedge-shaped or hole-shaped recesses were formed with a depth of about 10 μm and an interval of about 50 μm.

The metal salt for electroless plating was copper.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

1A and 1B show a first embodiment of the electroless plating method of the present invention. FIG. 1A is a perspective view of a resin substrate subjected to a surface roughening treatment, and FIG. 1B is a surface roughening treatment. FIG. 3C is a cross-sectional view of the resin substrate, and FIG. 6C is a cross-sectional view of the resin substrate subjected to the electroless plating after the roughening treatment. FIG. 2 is a perspective view of a polystyrene molded resin substrate in which Pd powder is kneaded as a plating catalyst. 1 is a resin substrate, 2 is a wedge-shaped recess (groove)
Parts 4 are electroless copper plating films.

The resin substrate 1 is made of polystyrene 5 cm × 5 cm
It is injection molded into a square with a thickness of 1 cm. Pd powder, which is a plating catalyst, is kneaded into polystyrene so that it serves as a nucleus for plating deposition.

As a roughening treatment using a metal needle on the resin substrate 1, the length is 5 cm, and the depth from the surface is about 10 μm.
A sharp groove of m, that is, the wedge-shaped recess (groove) 2 is about 50
It was formed at μm intervals. When the resin substrate 1 having the wedge-shaped recess (groove) 2 formed therein was immersed in an electroless copper plating solution for about 8 hours, the plating first grew vertically from the wedge-shaped recess (groove) 2 and then , The entire surface of the resin substrate 1 was covered by growing in the horizontal direction. That is, electroless plating having an average thickness of about 12 μm can be performed, and the surface of the plating film is flat without being affected by the concave portion of the wedge-shaped concave portion (groove) portion 2 formed on the resin substrate 1.

FIG. 3 is a first comparative example to the first embodiment, in which (a) is a perspective view of a resin substrate subjected to a roughening treatment,
(B) is a cross-sectional view of a resin substrate subjected to a roughening treatment, and (c) is a cross-sectional view of a resin substrate subjected to electroless plating after the roughening treatment. On the resin substrate 1 molded under the same conditions as in FIG.
As the roughening treatment, wedge-shaped concave portions (grooves) 2 having a length of 5 cm as in FIG. 1 and a depth of about 10 μm from the surface were formed at intervals of about 100 μm. When the resin substrate 1 thus processed was immersed in an electroless copper plating solution for about 8 hours, electroless copper plating particles 5 adhered to the wedge-shaped concave (groove) portion 2 as shown in FIG. 3 (c). However, it did not grow horizontally.

FIG. 4 is a second comparative example with respect to the first embodiment, in which (a) is a perspective view of a roughened resin substrate,
(B) is a cross-sectional view of a resin substrate subjected to a roughening treatment, and (c) is a cross-sectional view of a resin substrate subjected to electroless plating after the roughening treatment. On the resin substrate 1 molded under the same conditions as in FIG.
As a roughening treatment, the wedge-shaped concave (groove) portion 2 having a length of 5 cm as in FIG. 1 and having a depth of about 5 μm from the surface,
The layers were formed at the same intervals of about 50 μm as in FIG. When the resin substrate 1 thus processed was immersed in an electroless copper plating solution for about 8 hours, no plating precipitation reaction occurred as shown in FIG. 3 (c).

FIG. 5 is a third comparative example to the first embodiment, (a) is a perspective view of a resin substrate surface-roughened by chemicals, and (b) is a resin substrate surface-roughened by chemicals. And (c) is a sectional view of a resin substrate which has been subjected to electroless plating after being roughened by a chemical. 3 is a surface roughened by chemicals. The resin substrate 1 shown in FIG.
A roughening treatment was performed for about 15 minutes using the r acid / sulfuric acid mixed solution. Then, the resin substrate 1 having the surface 3 roughened by this chemical was dipped in an electroless copper plating solution for about 8 hours. As a result, as shown in FIG. 5 (c), a flat plating film having a thickness of about 12 μm was formed. Was formed.

6A and 6B show a second embodiment of the electroless plating method of the present invention. FIG. 6A is a perspective view of a resin substrate subjected to a surface roughening treatment, and FIG. 6B is a surface roughening treatment. FIG. 3C is a cross-sectional view of the resin substrate, and FIG. 6C is a cross-sectional view of the resin substrate subjected to the electroless plating after the roughening treatment. 6 is a hole-shaped recess (groove).

The resin substrate 1 is, as in the case of the first embodiment, made by injection molding polystyrene into a square of 5 cm × 5 cm to a thickness of 1 cm. Pd powder, which is a plating catalyst, is kneaded into polystyrene so that it serves as a nucleus for plating deposition.

On this resin substrate 1, as a roughening treatment using a metal needle, a groove having a hole diameter of about 500 μm and a depth of about 10 μm from the surface, that is, a hole-shaped concave portion 6 is formed. 5
It was formed at intervals of 0 μm. Then, this hole-shaped concave (groove) portion 6
When the resin substrate 1 on which the resin was formed is immersed in an electroless copper plating solution for about 6 hours, the plating first grows vertically from the hole-shaped recess (groove) 6 and then grows horizontally to form the resin substrate 1. Covered the entire surface of. That is, the average thickness is about 10μ
m electroless plating could be performed, and the surface of the plating film was flat without being affected by the concave portions of the hole-shaped concave portions (grooves) 6 formed on the resin substrate 1.

FIG. 7 is a first comparative example to the second embodiment, in which (a) is a perspective view of a roughened resin substrate,
(B) is a cross-sectional view of a resin substrate subjected to a roughening treatment, and (c) is a cross-sectional view of a resin substrate subjected to electroless plating after the roughening treatment. On the resin substrate 1 molded under the same conditions as in FIG.
As the surface roughening treatment, the same hole diameter as in FIG. 6 was about 500 μm, and the hole-shaped concave portions (grooves) 6 of about 10 μm from the surface in the depth direction were formed at intervals of about 100 μm this time. When the resin substrate 1 thus processed was dipped in an electroless copper plating solution for about 6 hours, electroless copper plating particles 5 were attached to the hole-shaped concave (groove) portions 6 as shown in FIG. 7C. However, it did not grow horizontally.

FIG. 8 is a second comparative example for the second embodiment, in which (a) is a perspective view of a resin substrate subjected to a roughening treatment,
(B) is a cross-sectional view of a resin substrate subjected to a roughening treatment, and (c) is a cross-sectional view of a resin substrate subjected to electroless plating after the roughening treatment. On the resin substrate 1 molded under the same conditions as in FIG.
As the roughening treatment, the hole-shaped concave (groove) portion 6 having the same hole diameter of about 500 μm as in FIG. 6 and about 5 μm in the depth direction from the surface is formed.
It was formed at the same intervals of about 50 μm as in FIG. When the resin substrate 1 thus processed was immersed in an electroless copper plating solution for about 6 hours, no plating deposition reaction occurred as shown in FIG. 7 (c).

FIG. 9 is a third comparative example to the second embodiment, in which (a) is a perspective view of a resin substrate surface-roughened by chemicals, and (b) is a resin substrate surface-roughened by chemicals. And (c) is a sectional view of a resin substrate which has been subjected to electroless plating after being roughened by a chemical. The resin substrate 1 shown in FIG. 2 was subjected to a roughening treatment for about 15 minutes using a Cr acid / sulfuric acid mixed solution. Thereafter, the resin substrate 1 having the surface 3 to be roughened by this chemical is immersed in an electroless copper plating solution for about 6 times.
After soaking for about 10 minutes, as shown in Fig. 9 (c)
A flat plating film having a thickness of m was formed.

As described above, the main point of the present invention is to eliminate the risk of roughening treatment by chemicals and poor workability. As a remedy, a mechanical recess is formed on a resin substrate kneaded with a plating catalyst. This makes it possible to deposit plating.

The mechanical surface-roughening treatment must be performed to a thickness not less than the thickness of the catalyst-free surface layer (skin layer) formed during resin molding. Further, even if the plating catalyst is exposed, electroless plating cannot be performed on a smooth surface without undulations. The following can be concluded from the various comparative examples described above.

In the case of electroless copper plating, the growth of plating proceeds as the film formation proceeds by repeating the deposition of metallic copper and the dissolution reaction of the deposited copper, so that C deposited as nuclei on the resin substrate is deposited.
As a stagnation point (active point) where u is not easily dissolved, a recess of about 10 μm or more is required in the depth direction from the surface. In addition, in order for the plating nuclei grown from the recess of the resin substrate to grow laterally after reaching the surface, about 5
It is necessary to form them at intervals of 0 μm. In addition, as the shape of the concave portion, the case of the wedge shape or the concentric circular hole shape has been described as an example, but any shape may be used as long as the above conditions are satisfied.

[0026]

EFFECTS OF THE INVENTION According to the electroless plating method of the present invention, mechanical recesses (having a depth of about 10 μm and an interval of about 50 μm) are formed on a resin substrate mixed with a plating catalyst, and then the Since electrolytic plating is performed, the effect that no roughening treatment with a chemical is required is exhibited.

[Brief description of drawings]

FIG. 1 shows a first embodiment of an electroless plating method of the present invention, in which (a) is a perspective view of a resin substrate subjected to a surface roughening treatment, and (b) is a resin subjected to the surface roughening treatment. Sectional drawing of a board | substrate, (c) is a sectional view of the resin board which electrolessly plated after the roughening process.

FIG. 2 is a perspective view of a polystyrene molded resin substrate in which Pd powder is kneaded as a plating catalyst.

FIG. 3 is a first comparative example for the first embodiment,
(A) is a perspective view of the roughened resin substrate, (b) is a cross-sectional view of the roughened resin substrate, and (c) is a cross section of the resin substrate subjected to the electroless plating after the roughening treatment. It is a figure.

FIG. 4 is a second comparative example with respect to the first embodiment,
(A) is a perspective view of the roughened resin substrate, (b) is a cross-sectional view of the roughened resin substrate, and (c) is a cross section of the resin substrate subjected to the electroless plating after the roughening treatment. It is a figure.

FIG. 5 is a third comparative example for the first embodiment,
(A) is a perspective view of a resin substrate roughened by chemicals,
(B) is a cross-sectional view of a resin substrate roughened by a chemical,
(C) is a cross-sectional view of a resin substrate subjected to electroless plating after being roughened by a chemical.

6A and 6B show a second embodiment of the electroless plating method of the present invention, in which FIG. 6A is a perspective view of a roughened resin substrate, and FIG. 6B is a roughened resin. Sectional drawing of a board | substrate, (c) is a sectional view of the resin board which electrolessly plated after the roughening process.

FIG. 7 is a first comparative example for the second embodiment,
(A) is a perspective view of the roughened resin substrate, (b) is a cross-sectional view of the roughened resin substrate, and (c) is a cross section of the resin substrate subjected to the electroless plating after the roughening treatment. It is a figure.

FIG. 8 is a second comparative example for the second embodiment,
(A) is a perspective view of the roughened resin substrate, (b) is a cross-sectional view of the roughened resin substrate, and (c) is a cross section of the resin substrate subjected to the electroless plating after the roughening treatment. It is a figure.

FIG. 9 is a third comparative example for the second embodiment,
(A) is a perspective view of a resin substrate roughened by chemicals,
(B) is a cross-sectional view of a resin substrate roughened by a chemical,
(C) is a cross-sectional view of a resin substrate subjected to electroless plating after being roughened by a chemical.

[Explanation of symbols]

1 resin substrate 2 wedge-shaped recess (groove) Surface roughened by 3 chemicals 4 Electroless plating film 5 Electroless plating particles 6 Hole-shaped recess (groove)

Continued front page    (72) Inventor Ryo Sato             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Wire Co., Ltd. Hidaka Factory F term (reference) 4K022 AA13 AA26 AA37 BA08 BA31                       BA35 CA02 CA04 CA21 CA29                       DA01                 5E343 AA02 AA12 BB24 CC73 DD33                       EE33 ER02 GG02

Claims (5)

[Claims] 1. An electroless plating method, which comprises performing a mechanical recess on a resin substrate and then performing electroless plating. 2. The electroless plating method according to claim 1, wherein the resin substrate is kneaded with a plating catalyst. 3. The electroless plating method according to claim 1, wherein the mechanical recess has a wedge shape or a hole shape. 4. The mechanical recess has a depth of about 10 μm,
The electroless plating method according to any one of claims 1 to 3, characterized in that the intervals are formed at about 50 µm. 5. The electroless plating method according to claim 1, wherein the metal salt for electroless plating is copper.