JPH04279092A - Manufacture of metal foil-plated board - Google Patents

Abstract

PURPOSE:To improve adhesive properties of a metal foil, heat resistance of solder by treating a surface of a polymer extrusion molded board to incorporate special surface moistening tension, therein, coating it with thermosetting primer, and then bonding the foil to a primer coating surface by using heat resistant adhesive. CONSTITUTION:A polyester extrusion molded board is corona discharged or plasma-processed at one or both side surfaces, and its surface moistening tension is set to 50dynes/cm or more. Then, the board is coated on one or both side surfaces with thermosetting primer made of epoxy resin primer containing curing agent, heat treated and a metal foil is press-bonded on the primer coating surface by using heat resistance adhesive. The adhesive contains 20-70 pts.wt. of acrylonitrilebutadiene copolymer solid at the ambient temperature containing carboxyl group and epoxy curing agent in 100 pts.wt. of epoxy resin containing 20-70wt.% of polyglycidylether.

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 metal foil-covered substrate used for electronic circuits, and more particularly, to a method for manufacturing the same substrate with excellent metal foil adhesion and solder heat resistance.

0002

[Prior Art] Conventionally, polyester extrusion molded boards, especially polyethylene terephthalate-based polyester extrusion molded boards, have excellent electrical properties, mechanical properties, chemical resistance, etc., so adhesives have been used on one or both sides of the boards. Metal foil is pasted together and used as an electronic circuit board, but the adhesion to the metal foil is not sufficient and the metal foil peels off during drilling, punching, or when soldering electronic components. There were some easy drawbacks.

0003

SUMMARY OF THE INVENTION The present invention provides a method for easily manufacturing a metal foil-clad substrate that improves the above-mentioned drawbacks of the prior art, that is, a metal foil-clad substrate that has excellent metal foil adhesion and soldering heat resistance. This is what we are trying to provide.

0004

[Means for Solving the Problems] The method for manufacturing a metal foil-clad board of the present invention includes (a) corona discharge treatment or plasma treatment on one or both sides of a polyester extrusion molded board to increase the surface wetting tension to 50 dynes/cm or more; The process of
This method is characterized by comprising the steps of (b) applying a thermosetting primer to the treated surface, and (c) bonding metal foil to the primer-coated surface using a heat-resistant adhesive.

[0005] The polyester extrusion board is particularly preferably a polyethylene terephthalate type polyester extrusion board. Further, the thermosetting primer is preferably an epoxy resin containing a curing agent.

[0006] The heat-resistant adhesive also contains one or more polyglycidyl ethers selected from polyglycidyl ethers represented by the following chemical formula (1) and polyglycidyl ethers represented by the following chemical formula (2). Epoxy resin 1 containing at least 18% by weight of glycidyl ether (I)
00 parts by weight, 20 to 70 parts by weight of an acrylonitrile butadiene copolymer that is solid at room temperature and has a carboxyl group in the molecule.
Parts by weight and an epoxy resin adhesive containing an epoxy curing agent are preferred.

[0007]

[Chemical formula 3]

[0008]

[C4]

[0009] Furthermore, the heat-resistant adhesive is preferably used in the form of a sheet formed in advance, and the heat-resistant adhesive is applied in advance to the metal foil to be bonded and used as an adhesive sheet with metal foil. is preferable.

[0010] The polyester extrusion molded board used in the present invention is made of polyester, preferably polyethylene terephthalate polyester, and various types of additives such as electrically insulating fillers such as talc and mica, fibrous reinforcing materials such as glass fiber, and heat stabilizers. The additives are melted and mixed,
Preferably, it is extruded into a plate shape with a thickness of 0.3 to 3 mm using a T-die.

[0011] Such a polyester extrusion molded board is subjected to corona discharge treatment or plasma treatment on one or both sides thereof, and this treatment can be easily carried out using commercially available treatment equipment. For example, corona discharge treatment requires
The plasma treatment can be performed using a corona surface treatment device manufactured by Kasuga Denki Co., Ltd., and a plasma treatment device manufactured by Toshiba Corporation. This surface treatment reduces the surface shedding tension of the polyester extrusion board to 50 dynes/
Make sure it is at least cm. If the surface wetting tension is less than 50 dynes/cm, sufficient adhesion to the metal foil cannot be obtained.

In the present invention, a thermosetting primer is then applied to one or both sides of the polyester extrusion molded board which has been subjected to the above treatment to have a surface wetting tension of 50 dynes/cm or more. The thermosetting primer is preferably an epoxy resin primer containing a curing agent. Various epoxy resins can be used, such as bisphenol type epoxy resin, novolak type epoxy resin,
Brominated epoxy resin, urethane-modified epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin,
Examples include glycidylamine type epoxy resins and heterocyclic epoxy resins, and two or more of these may be used in combination.

Various types of epoxy curing agents can be used in the thermosetting epoxy resin primer. Examples include amine curing agents, polyaminoamide curing agents, acids, acid anhydrides, dicyandiamide, basic active hydrogen compounds such as organic acid dihydrazides, imidazoles, amine imides, Lewis acids, blessed acid salts, and phenolic resins. It will be done. These can be used alone or in combination
More than one species can be used in combination.

[0014] In preparing a thermosetting primer, a suitable solvent is usually used to dissolve the above components and facilitate mixing of the components. As the solvent, for example, methyl ethyl ketone, methyl isobutyl ketone, toluene, methyl cellosolve, dimethyl formamide, etc. can be used alone or as a mixed solvent of two or more.

The thermosetting primer can be applied to the polyester extrusion molded board by a known method using a bar coater, roll coater, etc. The thickness of the coating film is not particularly limited, but is usually 1 to 100 ml. A range of 20 μm is preferred.

[0016] After applying a thermosetting primer to one or both sides of the polyester extrusion molded board with a surface wetting tension of 50 dynes/cm or more as described above,
The primer-coated surface is heat-treated at 120-200°C for 5-60 minutes, and then metal foil is crimped onto the primer-coated surface using a heat-resistant adhesive using a roll or batch method. A metal foil-covered substrate is obtained.

As mentioned above, the heat-resistant adhesive is made of one or more polyglycidyl ethers selected from the polyglycidyl ether represented by the chemical formula (1) and the polyglycidyl ether represented by the chemical formula (2). Glycidyl ether (I) at least 18% by weight, preferably from 20% to
100 parts by weight of an epoxy resin containing 70% by weight contains 20 to 70 parts by weight, preferably 30 to 65 parts by weight, of an acrylonitrile butadiene copolymer that is solid at room temperature and has a carboxyl group in the molecule, and an epoxy curing agent. Preferred are epoxy resin adhesives.

The polyglycidyl ether represented by the chemical formula (1) is, for example, Epicoat 1032, Epicoat 1032,
31S, YL-933, YL-934 (all of the above are trade names of Yuka Ciel Epoxy Co., Ltd.), YDG-4
It is commercially available as 14 (trade name of Toto Kasei Co., Ltd.), EPPN-501 (trade name of Nippon Kayaku Co., Ltd.), ESX-220 (trade name of Sumitomo Chemical Co., Ltd.), etc. Further, the polyglycidyl ether represented by the chemical formula (2) is, for example, Epicote 1
54, 180H, 157H, and YL-6241 (all of the above are trade names of Yuka Ciel Epoxy Co., Ltd.). The epoxy resin for the heat-resistant adhesive used in the present invention desirably contains such specific polyglycidyl ether in an amount of at least 18% by weight, preferably 20 to 70% by weight, and of course the total amount of the epoxy resin. may be filled with such polyglycidyl ethers. If the proportion of such specific polyglycidyl ether used is too small, the soldering heat resistance of the metal foil-covered substrate will decrease.

[0019] In the above-mentioned epoxy resin for heat-resistant adhesive used in the present invention, other epoxy resins that can be used in combination with the above-mentioned specific polyglycidyl ether (I) are not particularly limited, and various epoxy resins may be used. is available. For example, various bisphenol type epoxy resins, various novolac type epoxy resins, brominated epoxy resins, urethane-modified epoxy resins, alicyclic epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, heterocyclic epoxy resins, etc. These may be used in combination of two or more.

[0020] The heat-resistant adhesive used in the present invention contains a carboxyl group in the above molecules.
), solid acrylonitrile-butadiene copolymers include terminal-carboxylated acrylonitrile-butadiene copolymers, and terpolymers made by copolymerizing acrylonitrile, butadiene, and carboxyl group-containing monomers such as acrylic acid. etc. can be mentioned. Such a copolymer has an acrylonitrile content of 10 to 50% by weight, preferably 15 to 35% by weight, a carboxyl group content of 2 to 8% by weight, a molecular weight of 8000 or more, and a Mooney viscosity of ML1+4 (100%). C) is 10 or more, preferably 40 or more, and is solid with no fluidity at room temperature. Commercially available copolymers of this type include, for example, T
-4633, PNR-1HA (trade name of Nippon Synthetic Rubber Co., Ltd.), and Nipol 1072 (trade name of Nippon Zeon Co., Ltd.).

As mentioned above, the proportion of the carboxyl group-containing acrylonitrile butadiene copolymer used is 20 to 70 parts by weight, preferably 30 to 65 parts by weight, based on 100 parts by weight of the epoxy resin. If the proportion of the copolymer used is too small, problems such as the fluidity of the adhesive being so large that it protrudes to the edges when the metal foils are laminated will occur, and the adhesion of the metal foils will be reduced. Furthermore, if the proportion of the copolymer used is too large, the soldering heat resistance will decrease.

[0022] Various curing agents can be used as the curing agent to be added to the heat-resistant epoxy resin adhesive used in the present invention. Examples include amine curing agents, polyaminoamide curing agents, acids, acid anhydrides, dicyandiamide, basic active hydrogen compounds such as organic acid dihydrazides, imidazoles, amine imides, Lewis acids, Bronsted acid salts, and phenolic resins. It will be done. These may be used alone, or two
You may use more than one species in combination.

[0023] In preparing the heat-resistant adhesive, a suitable solvent is usually used to dissolve the above-mentioned components and facilitate mixing of the components. As the solvent, for example, methyl ethyl ketone, methyl isobutyl ketone, toluene, methyl cellosolve, dimethyl formamide, etc. are used alone or as a mixed solvent of two or more.

[0024] The heat-resistant adhesive used in the present invention may contain various additives as required. For example, calcium carbonate, titanium oxide, zinc oxide, silica,
Inorganic fillers such as alumina, hydrated alumina, and bentonite, coupling agents such as silicone-based or titanate-based coupling agents, flame retardants, colorants, and the like can be blended.

[0025] As a method of bonding metal foil using a heat-resistant adhesive in the present invention, for example, a heat-resistant adhesive prepared using a solvent as described above is applied to the thermosetting primer-coated surface of the polyester extrusion molded board described above. After the adhesive varnish is applied and the solvent is dried, a metal foil is layered on the adhesive layer and pressure bonded in a roll or batch manner. The crimping is carried out at elevated temperatures, usually between 60 and 200 degrees Celsius.
It is carried out at a temperature of

Furthermore, in the bonding of metal foils in the present invention, the above-described heat-resistant adhesive can be formed into a sheet and used as an adhesive sheet. To manufacture the adhesive sheet, for example, heat-resistant adhesive is uniformly heated and melted, and then melt-extruded using a T-die to form a sheet, or a heat-resistant adhesive prepared using a solvent as described above is used. There is a method of applying adhesive varnish to release paper such as silicone coated paper and drying it to form a sheet. There is no particular restriction on the shape of the sheet, and it may be of a shape and size that matches the shape of the extruded polyester board, or it may be in the form of a continuous roll. The thickness of the sheet is usually 10
Various thicknesses are selected within the range μm to 200 μm. Such an adhesive sheet is overlaid on the thermosetting primer-coated side of the polyester extrusion molded board, a metal foil is further laminated thereon, and the sheet is crimped in a roll or batch manner at an elevated temperature as described above. .

Furthermore, in the bonding of metal foils in the present invention, the heat-resistant adhesive described above can be applied to the metal foils in advance to form an adhesive sheet with metal foils. The adhesive sheet with metal foil can be manufactured by melting and extruding the adhesive onto the metal foil using a T-die, or by applying adhesive varnish onto the metal foil and drying it, in the same way as manufacturing the adhesive sheet. There is a method of providing an adhesive sheet layer on the metal foil surface. The thickness of the adhesive layer of the adhesive sheet with metal foil can be the same as that of the adhesive sheet described above. If the adhesive side of such a metal foil-covered adhesive sheet is superimposed on the thermosetting primer coated side of the polyester extrusion molded board and pressed in a roll type or batch type at an elevated temperature as described above, A metal foil-clad substrate of the present invention is obtained.

The metal foil-covered substrate obtained by the manufacturing method of the present invention has excellent metal foil adhesion and solder heat resistance, and prevents peeling of the metal foil during drilling, punching, or soldering of electronic components. It doesn't happen.

[0029]

[Examples] The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 A polyethylene terephthalate extrusion molded board (manufactured by Unitika Co., Ltd., thickness 1.0 mm) was subjected to corona discharge using a corona surface treatment device (manufactured by Kasuga Denki Co., Ltd.) at a feed rate of 7 m/min and a current of 3 A. The surface wetting tension was 50 dynes/cm. On this treated surface, 100 parts by weight of epoxy resin (trade name Epicoat 1001, manufactured by Yuka Ciel Epoxy Co., Ltd., epoxy equivalent weight 470), 4 parts by weight of dicyandiamide,
and tris(dimethylaminomethyl)phenol 0.8
A thermosetting primer prepared by dissolving part by weight in dimethylformamide at a solid concentration of 30% by weight was applied by a roll coater method, and heat treated at 150° C. for 30 minutes. The thickness of the primer was 10 μm.

Next, commercially available polyglycidyl ether corresponding to the compound represented by the above chemical formula (1) (trade name Epicote 1031, manufactured by Yuka Ciel Epoxy Co., Ltd.)
S, epoxy equivalent 195) 40 parts by weight, commercially available epoxy resin (Yuka Ciel Epoxy Co., Ltd. trade name Epicote 828, epoxy equivalent 190) 60 parts by weight, commercially available room temperature solid carboxyl group-containing acrylonitrile butadiene copolymer (Nippon Gosei) Rubber company product name T-4633)
60 parts by weight, 25 parts by weight of diaminodiphenylsulfone,
and 0.5 parts by weight of BF3-monoethylamine complex,
A heat-resistant adhesive varnish obtained by dissolving the solid content in dimethylformamide to a solid content of 35% by weight was coated onto the primer-coated surface using a roll coater to a dry thickness of 60 μm.
Copper foil (Nippon Mining Co., Ltd. product name)
JTC 1 OZ) were overlapped and thermocompression bonded at 150°C. Furthermore, it was heat-cured in an oven at 130° C. for 10 hours to obtain a metal foil-covered substrate. The characteristics of the substrate were as shown in Table 1.

On the other hand, when the polyester extrusion molded board was corona discharge treated at a feed rate of 10 m/min and the surface wetting tension was 48 dynes/cm (Comparative Example 1), and no thermosetting primer was applied. Even in the case where there was no metal foil (Comparative Example 2), a metal foil-covered substrate was manufactured in the same manner as in Example 1, and the characteristic values of the substrate were as shown in Table 1.

[0033]

[Table 1]

Notes to Table 1: Each test method was as follows (the same applies to the following examples). *1... Tested according to JIS C-6481. *2... According to JIS C-6481, the test piece was floated in a solder bath at 260°C for 20 seconds, and then visually inspected for abnormalities such as blistering. *3... The presence or absence of the adhesive used for bonding the metal foils protruding from the edge of the substrate was visually inspected.

As is clear from Table 1, the metal foil-covered substrate obtained in Example 1 has higher metal foil peeling strength and better solder heat resistance than the substrates obtained in Comparative Examples 1 and 2. It can be seen that it has excellent properties and is excellent in substrate processing and handling.

Examples 2 to 8 Comparative Examples 3 to 6 Metal foil-covered substrates were manufactured in the same manner as in Example 1, except that the formulation of the heat-resistant adhesive was changed as shown in Table 2. The properties of the obtained substrate were as shown in Table 2.

[0037]

[Table 2]

Notes to Table 2: *1... Polyglycidyl ether represents the following. A: Yuka Ciel Epoxy Co., Ltd., trade name Epicote 1031S, epoxy equivalent: 195, corresponding to the compound represented by chemical formula (1). B: Yuka Ciel Epoxy Co., Ltd., trade name Epicote 1032, epoxy equivalent: 170, corresponding to the compound represented by chemical formula (1). C: Yuka Ciel Epoxy Co., Ltd. Product name YL-93
3, epoxy equivalent: 190, corresponding to the compound represented by chemical formula (1). D: Sumitomo Chemical Co., Ltd. trade name ESX-220, epoxy equivalent: 210, corresponding to the compound represented by chemical formula (1). E: Yuka Ciel Epoxy Co., Ltd., trade name: Epicote 154, epoxy equivalent: 180, corresponding to the compound represented by chemical formula (2). F: Yuka Ciel Epoxy Co., Ltd., trade name Epicote 180H, epoxy equivalent: 210, corresponding to the compound represented by chemical formula (2). G: Yuka Ciel Epoxy Co., Ltd. Product name YL-62
41, epoxy equivalent weight 245, corresponding to the compound represented by chemical formula (2). *2...Product name of Yuka Ciel Epoxy Co., Ltd., epoxy equivalent: 190 *3...Product name of Nihon Gosei Rubber Co., Ltd., carboxyl group-containing acrylonitrile butadiene copolymer that is solid at room temperature *4
...Gutudoritsuchi's product name, room temperature liquid acrylonitrile butadiene copolymer containing carboxyl group

003
9] As is clear from Table 2, the metal foil-covered substrates obtained in Examples 2 to 8 have excellent metal foil adhesion and soldering heat resistance, so the substrates are easy to process and handle. I understand that.

Example 9 The same polyester extrusion board used in Example 1 was heated to 0.5 T of a mixed gas with an oxygen/nitrogen weight ratio of 1/1.
Plasma treatment was performed for 1 minute in an atmosphere of orr, and the surface wetting tension was set to 52 dynes/cm. Using this surface-treated board, a metal foil-covered substrate was manufactured in the same manner as in Example 1 except for the above. The properties of the obtained substrate were as shown in Table 3.

[0041]

[Table 3]

Example 10 The heat-resistant adhesive varnish used in Example 1 was applied to a silicone-coated release paper to a dry thickness of 60 μm.
It was dried in an oven at 50° C. for 10 minutes to obtain an adhesive sheet with release paper.

[0043] The adhesive side of this adhesive sheet with release paper was placed on the primer-coated side of a thermosetting primer-coated polyester extrusion molded board produced in the same manner as in Example 1, and after being pressed lightly with hand, it was released. Remove the pattern,
The copper foil used in Example 1 was superimposed on that surface and heated to 150°C.
It was heat-pressed. Next, the adhesive was cured by heating in an oven at 130° C. for 10 hours to obtain a metal foil-covered substrate.

The properties of the obtained substrate were as shown in Table 4. Further, after the adhesive sheet with release paper was left at 5° C. for 3 months, a metal foil-covered substrate was manufactured using the adhesive sheet in the same manner as described above. The characteristics of the substrate were as shown in Table 4. That is, substrates with excellent adhesion and soldering heat resistance were obtained both when using the adhesive sheet with release paper immediately after manufacture and when using the adhesive sheet after being left for 3 months.

[0045]

[Table 4]

Example 11 The heat-resistant adhesive varnish used in Example 1 was applied to the copper foil used in Example 1 to a dry thickness of 60 μm.
An adhesive sheet with copper foil was obtained by drying it in an oven at 50° C. for 10 minutes.

[0047] The adhesive side of the above copper foil-coated adhesive sheet was placed on the primer-coated side of a thermosetting primer-coated polyester extrusion molded board produced in the same manner as in Example 1, and thermocompression bonded at 150°C. Next, the adhesive was cured by heating in an oven at 130° C. for 10 hours to obtain a metal foil-covered substrate.

The properties of the obtained substrate were as shown in Table 5. In addition, the adhesive sheet with copper foil was heated at 5°C for 30 minutes.
After leaving it for a month, a metal foil-covered substrate was obtained using the adhesive sheet in the same manner as described above. The characteristics of the substrate were as shown in Table 5. As is clear from Table 5, the case of using the adhesive sheet with copper foil immediately after manufacture and the case of using the adhesive sheet with copper foil immediately after manufacture, and
Even when the adhesive sheet was used after being left for a month, a substrate with excellent adhesion and soldering heat resistance was obtained.

[0049]

[Table 5]

[0050]

[Effects of the Invention] The metal foil-covered substrate obtained by the method of the present invention has excellent metal foil adhesion and solder heat resistance, and does not cause peeling of the metal foil during drilling or punching, or when soldering electronic components. It does not cause any inconvenience and has excellent processing and handling properties.

Claims (6)

[Claims] Claim 1: (a) a step of treating one or both sides of a polyester extrusion board with corona discharge treatment or plasma treatment to give a surface shear tension of 50 dynes/cm or more; (b) applying a thermosetting primer to the treated surface. and (c) bonding metal foil to the primer-coated surface using a heat-resistant adhesive. 2. The method for manufacturing a metal foil-clad substrate according to claim 1, wherein the polyester extrusion molded board is a polyethylene terephthalate-based polyester extrusion molded board. 3. The method for producing a metal foil-clad substrate according to claim 1, wherein the thermosetting primer is an epoxy resin containing a curing agent. [Claim 4] The heat-resistant adhesive has the following chemical formula (1):
One or more polyglycidyl ethers (I) selected from polyglycidyl ethers represented by the following formula (2) and polyglycidyl ethers represented by the following chemical formula (2):
An epoxy resin adhesive comprising 100 parts by weight of an epoxy resin containing at least 18% of A method for manufacturing a metal foil-clad substrate according to claim 1, claim 2, or claim 3. [Chemical formula 1] [Chemical formula 2] 5. The method of manufacturing a metal foil-clad substrate according to claim 1, 2, 3, or 4, wherein the heat-resistant adhesive is used in the form of a sheet. 6. Manufacturing a metal foil-clad substrate according to claim 1, 2, 3, 4, or 5, wherein a heat-resistant adhesive is applied to the metal foil to be bonded. Method.