JPH0794895A - Electromagnetic shielding material - Google Patents

Abstract

PURPOSE:To provide an electromagnetic shielding material of high reliability by forming a stable and uniform nonelectrolytic plating layer on a plastics material, especially, on thermosetting resin wherein nonelectrolytic plating is difficult. CONSTITUTION:Adhesive agent layer 4 for plating composed by adding inorganic filler of 50-150wt.% wherein the average grain diameter is 5mum or shorter and water content is 0.1wt.% or smaller to thermosetting resin of 100wt.% are formed on both surfaces of plastic material 1, and nonelectrolytic plating layers 5 and rust-proof coating layers 6 are formed on the adhesive agent layers 4. Usually, epoxy resin and its hardner are used as thermosetting resin. Carbonate of alkaline earth metal, or sulfate of alkaline earth metal, or carbonate of alkaline earth metal and alkaline earth metal are used as inorganic filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shield material which is made conductive by using electroless plating on a plastic material.

[0002]

2. Description of the Related Art Electronic parts and housings of office automation equipment such as personal computers are lightweight and have a good appearance, and have been made plastic and downsized in order to realize a low price. It is defenseless.

Conventionally, in order to block electromagnetic noise of electronic parts and housings of the above-mentioned OA equipment, a plastic material is coated with an electromagnetic shield coating (Japanese Patent Laid-Open No. 60-4569), or the surface is electroless plated (special feature). Kaihei 5-371
No. 72) is formed.

[0004]

However, the electromagnetic wave shielding paint does not have a sufficient electromagnetic noise shielding effect. On the other hand, although the electroless plating has a sufficient effect of blocking electromagnetic noise, as described in JP-A-5-37172, a plastic material that can be electroless plated by a simple pretreatment is ABS or Limited to polycarbonate, etc.

In particular, since it is extremely difficult to form a stable electroless plating layer on an electronic component such as a thermosetting resin printed circuit board, no treatment for blocking electromagnetic noise has been performed.

The present invention provides a highly reliable electromagnetic wave shield by forming a stable and uniform electroless plating layer on a plastic material, particularly a thermosetting resin material that has heat resistance and is difficult to electroless plate. Intended to provide material.

[0007]

In order to solve such a problem, the present inventor has earnestly studied and, as a result, forms an adhesive layer for plating on a plastic material and then forms an electroless plating layer. Based on this finding, the present invention has been completed.
That is, the present invention relates to a thermosetting resin or resin composition 10
The average particle size is 5 μm or less and the water content is 0.
An adhesive for plating is manufactured by filling 50 to 150 parts by weight of an inorganic filler of 1% by weight or less. The plating adhesive thus formed is applied to at least one side of a plastic material to form a plating adhesive layer, and an electroless plating layer and a rust preventive coating layer, or an electroless plating layer and a rust preventive plating layer are formed on the adhesive layer for plating. I will do it.

Usually, an epoxy resin and its curing agent are used as the thermosetting resin. Especially when the plastic material is an epoxy resin, it is preferable to use an epoxy resin as the thermosetting resin forming the adhesive layer, and when the plastic material is a phenol resin, a phenol resin is used as the thermosetting resin forming the adhesive layer. Is preferably used.

When the affinity between the plastic material and the plating adhesive layer is lacking, a stable and uniform electroless plating layer can be formed by providing an undercoating agent layer between the two.

As the inorganic filler, magnesium carbonate,
One or more salts selected from the group consisting of carbonates of alkaline earth metals such as calcium carbonate and barium carbonate and sulfates of alkaline earth metals such as magnesium sulfate, calcium sulfate and barium sulfate are used.

The inorganic filler has an average particle size of 5 μm or less, preferably 0.1 to 3 μm, and it is possible to control the content of water to 0.1% by weight or less so that the electroless plating layer is uniform and has high peel strength. Is important for forming.

The selection of the type and average particle size of the above-mentioned inorganic filler is carried out in the pretreatment step of electroless plating such as polishing, acid cleaning, alkali cleaning, water cleaning, hot water cleaning after the formation of the adhesive layer for plating. It is important for the inorganic filler to elute or fall off to form innumerable pores on the surface of the plating adhesive layer. Such innumerable pores contribute to the improvement of the anchoring effect of electroless plating, and further to the improvement of the peel strength from the plating adhesive layer.

The adhesive composition for forming the adhesive layer for plating includes a thermosetting resin and an inorganic filler, as well as a leveling agent, a surfactant, an acrylonitrile-butadiene rubber with or without a functional group, and an organic compound. Solvent or thickener,
Furthermore, a coloring pigment or a dye can be used if necessary.

In producing the electromagnetic wave shield material of the present invention, for example, an epoxy resin, a filler such as calcium carbonate, a leveling agent, an organic solvent, a coloring agent and the like are kneaded to prepare a main component of the adhesive composition. The same amount of curing agent as the epoxy resin is added to the main component of the adhesive composition. A polyamine compound or the like is used as the curing agent. Then, the adhesive composition containing the curing agent is applied to the plastic material 1 by a screen printing method, a roll coater method or the like (see FIG. 1). The plastic material 1 is, for example, a printed wiring board having an electric signal circuit 2 formed on both sides and having a resist ink layer 3. The plastic material 1 coated with the adhesive composition is heat-treated at 130 to 160 ° C. for 15 to 30 minutes to be cured to form the adhesive layer 4 for plating.

The formed plating adhesive layer 4 is subjected to electroless plating of 1 to 3 μm through pretreatment steps of electroless plating such as buffing, alkali cleaning, acid cleaning, water cleaning, and catalyst layer formation. As the electroless plating solution, a plating solution containing copper or nickel is preferable in terms of the balance between the electromagnetic wave shielding effect and the cost. A combination of copper and nickel is also preferable.

Subsequently, the electroless plating layer 5 is rust-proof coated to form an electromagnetic wave shielding material having a rust-preventive coating layer 6 (see FIG. 1).
reference). As the anticorrosive paint, melamine resin paint, urethane resin paint, epoxy resin paint, acrylic resin paint, etc. are used. Of course, it is safe to use anti-rust plating such as nickel instead of anti-rust coating.

[0017]

EXAMPLES (Preparation of Adhesive Composition) Epoxy resins, inorganic fillers, leveling agents, organic solvents and colorants shown in Table 1 in the weight ratios shown in Table 1 were placed in a container with a stirrer and kneaded. An adhesive composition (main ingredient) is prepared.

[0018]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 and 2 Adhesive compositions (base) using the inorganic fillers shown in Table 2
100 parts by weight of 15 parts by weight of 4,4-diaminodiphenylmethane as a curing agent are mixed to form an epoxy resin plate with 2 parts.
It was screen-printed with a thickness of 0 μm and heat-treated at 150 ° C. for 30 minutes. After the pretreatment of the above electroless plating, the formed plating adhesive layer was subjected to electroless copper plating using a plating solution (328A) manufactured by Secret Japan. The surface of the electroless copper-plated layer was observed under a microscope at a magnification of 100 to confirm the presence or absence of pinholes, and the results shown in Table 2 were obtained.
Subsequently, an epoxy resin coating was applied on the electroless copper plating layer and baked to manufacture an electromagnetic wave shielding material. Make a cut on the coated surface with a width of 25 mm, pulling speed 50 mm
The peel strength was measured in / min and the results shown in Table 2 were obtained. In Example 5, 75 parts by weight of calcium carbonate and 75 parts by weight of barium sulfate were used instead of 150 parts by weight of calcium carbonate.

[0020]

[Table 2]

Example 6 and Comparative Examples 3 and 4 An electric circuit was formed on both sides of a double-sided copper-clad epoxy resin substrate, and a printed wiring board using S-222 manufactured by Taiyo Ink Mfg. Co., Ltd. as a solder resist ink was used. An adhesive layer for plating was formed, electroless copper plating was performed, and rust-preventive coating was performed in the same manner as in No. 1 to produce an electromagnetic wave shielded printed wiring board (Example 6). A shield substrate (Comparative Example 3) and a shield-free substrate (Comparative Example 4) coated with a copper acrylic resin paint (MCP1000 manufactured by Mitsubishi Petrochemical Co., Ltd.) instead of the electroless copper plating layer and a shield-free substrate (Comparative Example 4) were added and the shield test was conducted under the conditions shown in Table 3. And then
The results shown in Table 3 were obtained.

[0022]

[Table 3]

Examples 7 and 8 and Comparative Example 5 The same as Example 1. However, when an electromagnetic wave shield material is manufactured using calcium carbonate having an average particle size shown in Table 4,
The results shown in Table 4 were obtained.

[0024]

[Table 4]

[0025]

According to the present invention, since the electroless plating is performed on the plating adhesive layer, it is possible to form an electromagnetic wave shielding material having an electroless copper plating layer having high peel strength without pinholes. In particular, by controlling the water content of the inorganic filler constituting the adhesive layer for plating to be 0.1% by weight or less, it is possible to manufacture an electromagnetic wave shield material having high peel strength without pinholes. Further, as shown in Table 3, the electromagnetic wave shielding effect is remarkably improved by this electroless plating layer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electromagnetic wave shield substrate material of the present invention.

[Explanation of symbols]

 1 Plastic material 4 Adhesive layer for plating 5 Electroless plating layer 6 Anticorrosion coating layer

Front Page Continuation (72) Inventor Taku Nonaka 3-15-5 Higashi Ueno, Taito-ku, Tokyo Within Diamond Bond Co., Ltd. (72) Inventor Shingo Sasaki 4085 Nakatsu, Aikawa-cho, Aiko-gun, Kanagawa Diamond Bond Atsugi Factory (72) Inventor Tomohisa Uemura 4085, Nakatsu, Aikawa-cho, Aiko-gun, Kanagawa DIABOND Kogyo Co., Ltd. Atsugi Plant (72) Inventor Toshiaki Hagino 5 1850 Shinba-cho, Kohoku-ku, Yokohama, Kanagawa

Claims (3)

[Claims] 1. A plating comprising 50 to 150 parts by weight of an inorganic filler having an average particle size of 5 μm or less and a water content of 0.1% by weight or less, based on 100 parts by weight of a thermosetting resin or a resin composition. Electromagnetic wave shield material in which an adhesive layer for plastics is formed on a plastic material, and electroless plating and rust-preventive coating or rust-preventive plating are formed on the adhesive layer. 2. An electromagnetic wave shield material, wherein the thermosetting resin according to claim 1 is an epoxy resin and a curing agent therefor. 3. An electromagnetic wave shield material, wherein the inorganic filler according to claim 1 is a carbonate or / and a sulfate of an alkaline earth metal.