JPH01286821A - Manufacture of copper laminated sheet - Google Patents

Abstract

PURPOSE:To bring strong adhesive force to a copper foil under an adhesive condition of low pressure and a short period of time, by a method wherein an epoxy adhesive agent compounded with an imidazole compound is used for manufacturing of a copper plated laminated sheet to be obtained by impregnating the sheet with a resin solution comprised of side chain double bond type resin, laminating and sticking the same and a copper foil together. CONSTITUTION:A publicly known method such as impregnation of a sheet base material is adopted to impregnate a sheetlike base material with side chain double bond type resin whose main chain is a backbone polymer containing a vinyle monomer unit having a functional group and side chain is a branch possessing carbon-carbon double bond which is comprised by constituting through the main chain and capable of making radical reaction. At the time of adhesion between a copper foil and resin impregnated base material, the copper foil to which an adhesive agent is applied and the impregnated base material are laminated together and the adhesion and cure of impregnated resin are performed at a time. It is enough by only mixing up with each other epoxy resin and imidazole which are liquid at the normal temperature respectively to prepare the adhesive agent. Although an epoxy compound of the adhesive agent is good with a wide use bisphenol A type epoxy resin, an epoxy compound which is rich in flexibility is preferable to reduce residual stress.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laminate for electrical circuits, and more particularly to a method for manufacturing a copper-clad laminate.

BACKGROUND OF THE INVENTION In the present invention, a copper-clad laminate refers to a copper-clad laminate for electric circuits used, for example, as a substrate for various electronic components, and its shape is such that the thickness is approximately 0.5 to 5 m+i. A plate-like object.

Conventionally, these copper-clad laminates are made by heating and semi-curing a phenolic resin based on paper or an epoxy resin based on glass cloth to create a prepreg, which is then laminated and cured under pressure. It is true. However, in this case, raw material costs and equipment costs are high, and the process is complicated.

In order to improve these problems, a method has recently been developed in which paper is used as a base material, impregnated with liquid unsaturated polyester resin, and continuously molded and heated to harden. However, unsaturated polyester resin copper-clad laminates inherently have a drawback of poor heat resistance. As a means to solve these drawbacks, the inventors of the present invention have published Japanese Patent Application No. 81-266128 (Japanese Patent Application No. 81-2).
68129 etc. proposed the use of a type of side chain double bond type resin with excellent heat resistance and radical curability in laminates for electrical circuits.

In the method of manufacturing copper-clad laminates, when bonding the copper foil to the laminate under heat, it is desirable to bond the copper foil to the laminate under as low pressure and as short a time as possible from the viewpoint of the above-mentioned improvement objective. The term "low pressure and short time" as used herein refers to a pressure of at least 5 kg/cj or less and a time of 30 minutes or less. However, under such low-pressure, short-time bonding conditions, it is difficult to find an effective thermal bonding adhesive that has strong adhesion between the laminate made of this double-bond side chain resin and copper foil. It was difficult.

The aforementioned paper-based phenolic resin copper-clad laminates generally have a phenolic resin adhesive applied to the copper foil in advance; Epoxy resin copper-clad laminates use copper foil that is not specially coated with adhesive.

The present inventors used the above-mentioned commercially available copper foil coated with a phenolic resin adhesive, but were unable to develop effective adhesive strength under the above-mentioned low pressure and short-time bonding conditions.

Problems to be Solved by the Invention In view of the current situation, the present invention provides a method for manufacturing a copper-clad laminate consisting of a base material impregnated with a side chain double bond type resin and copper foil, under low pressure and short time bonding conditions. By providing an effective adhesive that provides strong adhesion to copper foil.

Means for Solving the Problems The present inventors have developed a method of manufacturing copper-clad laminates consisting of a sheet-like base material impregnated with side chain double bond type resin and copper foil, using low pressure,
After searching for various adhesives that have strong adhesion to copper foil under short-time bonding conditions, we found that epoxy-based adhesives are good, and adhesives that use imidazole compounds as hardeners are particularly effective; As an adhesive for copper-clad laminates for electrical circuits, including peel strength, soldering heat resistance, electrical insulation, and chemical resistance.
It was discovered that the present invention exhibits well-balanced performance, and the present invention was completed.

That is, the gist of the present invention is to provide a method for producing a copper-clad laminate in which a plurality of sheet-like base materials impregnated with a side chain double bond type resin are laminated and copper foil coated with an adhesive is laminated on one or both sides of the sheet-like base material. , a method for manufacturing a copper-clad laminate using an epoxy adhesive containing an imidazole compound as an adhesive.

Hereinafter, the content of the present invention will be explained in detail.

The side chain double bond type resin referred to in the present invention is a polymer composed of a main chain and a side chain, where the main chain is a backbone polymer containing a vinyl monomer unit having a functional group, and the side chain is a polymer comprising a vinyl monomer unit having a functional group. refers to a side chain double bond type resin which is a branch having a radically reactive carbon-carbon double bond formed through a functional group of the main chain, and also refers to a vinyl monomer constituting the main chain. The unit is a vinyl monomer unit having a functional group as an essential unit, and if necessary, a vinyl monomer unit not having a functional group is included therein, and these units are polymerized to form a main chain. Examples of the seven polymers constituting the above essential units include acrylic acid, methacrylic acid, maleic anhydride, maleic acid monoester, vinyl monomers having carboxyl groups as functional groups, glycidyl methacrylate, glycidyl acrylate, etc. Vinyl monomers having glycidyl groups, allyl alcohol, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate,
Vinyl monomers having a hydroxyl group as a functional group such as 2-hydroxypropyl acrylate and N-methylolacrylamide are typical examples, and in particular, =iilp≠older is most preferably used for acrylic acid d and methacrylic acid.

In the present invention, the vinyl monomer unit having a functional group may be present as an active functional group when the main chain is formed by polymerization, or may be polymerized by reacting the side chain described below with the functional group of the monomer in advance. It refers to a type of monomer unit that has a functional group that serves to form a side chain into the main chain, regardless of whether it forms a main chain.

Non-functional monomers include styrene,
α-Methylstyrene, chlorostyrene, vinyltoluene, vinyl chloride, vinylidene chloride, vinyl bromide, acrylonitrile, ethylene, propylene, butadiene, (meth)acrylic ester, vinyl acetate, vinyl propionate, diester maleate, ethylvinylbenzene etc.

The weight average molecular weight of the main chain composed of these and nil monomer units is 500 to 400,000, preferably 10,000 to 200,000. This value is appropriately selected depending on the type of side chain. This makes the mechanical properties insufficient, and conversely, if it exceeds 400,000, the resin impregnation into the base material (paper etc.) will be poor, both of which are not preferred. The amount of monomer units having functional groups in the main chain is related to the density of the side chains, and since it affects the curing reactivity between the side chains, an appropriate ratio is selected. The amount is preferably 1 to 2 mol, more preferably 0.4 to 1.
It is 5 moles.

The side chain referred to in the present invention refers to a chain having a >C-C double bond at the end or in the middle, and which forms a branch on the main chain via its functional group. An example of a general formula is (hereinafter in the margin).

(1) In the formula, R1 to R3 are hydrogen or a methyl group, n represents an integer of 0 to 5, (in the old formula, R4 is hydrogen or a methyl group, L and L2
represents 10- or -NH-, represents X1 and X or a C to C16 hydrocarbon group or a hydrocarbon group connected by an ether bond, and in this X and
And the carbon atom bonded to the oxygen adjacent to X2 is 1
or secondary carbon, and B is an aliphatic, alicyclic or aromatic hydrocarbon group up to C2o.

(III) In the formula, R5 is hydrogen or a methyl group.

Note that the side chains and side chains of the double bond type resin according to the present invention are not limited to these, and any type that can form a crosslink between side chains by a radical reaction using a crosslinking vinyl monomer can be used.

Next, a method for producing the side chain double bond type resin used in the present invention will be outlined.

That is, various methods can be employed to introduce a side chain having a double bond at the end of the side chain into the polymer constituting the main chain. Some examples are as follows.

(b) One epoxy group of a compound having a jepoxy group such as a suphenol type diglycidyl ether type epoxy group is reacted with the carboxyl group of the functional group of the main chain, and the remaining epoxy group and (meta) React with acrylic acid.

ω The carboxyl group of the functional group of the main chain is reacted with glycidyl (meth)acrylate.

b) Reacting the epoxy group of the main chain functional group with (meth)acrylic acid.

ω React a diisocyanate compound with hydroxyethyl (meth)acrylate to create a reaction product that has monoisocyanate as its main component and contains almost no diisocyanate compound, and then react the incyanate contained in this reaction product with the hydroxyl group of the main chain polymer. .

In the exemplified method, the main chain was copolymerized first, but of course in the present invention, the reaction to form the side chain is performed first, and such monomers are copolymerized last to form the side chain terminal. A side chain double bond type resin containing a (meth)acryloyl group or the like may be produced.

For curing, a curing agent may be added and a crosslinking vinyl monomer such as styrene described below may be used.

The vinyl monomer for crosslinking is not particularly limited, but monofunctional hydrocarbon Qjffi monomers include styrene, vinyltoluene, chlorostyrene, methyl acrylate, ethyl acrylate, butyl acrylate, Included are 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate, benzyl methacrylate, dibutyl maleate, dioctyl maleate, vinyl acetate, vinyl propionate, and the like. These monomers may be used in combination of two or more.

Among the vinyl monomers for crosslinking, polyfunctional hydrocarbon monomers include divinylbenzene and derivatives thereof, diene compounds such as cyclopentadiene and butadiene, divinyl ester compounds, divinyl urethane compounds, and the like. These polyfunctional hydrocarbon monomers must be compounds that can be copolymerized with the above-mentioned monofunctional derivatives, and those that form a uniform copolymer are particularly preferred.

If necessary, fillers, reinforcing agents, mold release agents, colorants, flame retardants, curing accelerators, stabilizers, etc. can be used in combination with the resin liquid impregnated into the sheet-like base material to further enhance its performance. can.

The sheet-like base material can be the same as the base material used for conventional laminates, such as glass fiber cloth, glass nonwoven fabric, etc., or cellulose fibers such as kraft paper, linter paper, etc. Refers to sheet-like materials such as paper.

The sheet-like base material is impregnated with the side chain double bond type resin, etc. by a known method such as dipping the sheet base material, supplying a resin liquid to the upper surface of the sheet base layer, or roll coating. The liquid is removed by a squeezing roll.

The epoxy compound of the adhesive used in the present invention is as follows:
A general-purpose bisphenol A type epoxy resin may be used, but an epoxy compound with high flexibility is desirable in order to reduce residual stress. For example, flexible epoxy resins such as dimer acid diglycidyl ether, polyalkylene oxide diglycidyl ether, neopentyl glycol diglycidyl ether, 1.6 hexanediol diglycidyl ether, and bisphenol A alkylene oxide adduct diglycidyl ether are used. or a mixture of these. Furthermore, in order to impart flexibility, terminal aminobutadiene nitrile rubber (ATBN) or terminal carboxyl group butadiene nitrile rubber (CTBN) may be added, or an epoxy resin modified with the above rubber may be used. It's okay. It is usually desirable to use a mixture of these.

The imidazole compounds used in the present invention include monosubstituted imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-stearylimidazole, and 2-phenylimidazole, as well as 2-ethyl-4-methylimidazole, 2-phenylimidazole, and the like. Examples of the disubstituted imidazole include phenyl 4-methylimidazole, 1-benzyl 2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2isopropylimidazole, and 1-cyanoethyl-2-undecylimidazole. Examples of tri- and tetrasubstituted imidazoles include 1-cyanoethyl-2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-phenyl-4.5-bis[cyanoethoxymethylcoimidazole. However, the present invention is not limited to these, but is applicable to general imidazole compounds having an imidazole ring.

The adhesive is manufactured by using an epoxy resin that is liquid at room temperature and an imidazole compound that is liquid at room temperature, such as 1-cyanoethyl-2-ethyl-4-methylimidazole and 1-cyanoethyl-2-phenyl-4.
．． 5bis[cyanoethoxymethylcoimidazole may be simply mixed, but imidazole that is solid at room temperature may be thoroughly ground and then dispersed using a three-roll mill or the like. Also, by dispersing or dissolving it using a suitable solvent,
It is also convenient to adjust the viscosity to match the coating process.

Note that the copper foil used in the present invention refers to copper foil generally used for copper-clad laminates for electric circuits, that is, electrolytic copper foil and rolled copper foil, and the adhesive is applied to these copper foils using a normal roll coater. , a blade coater, or a wire bar coater. Further, it is desirable that the copper foil coated with the adhesive be subjected to a heat treatment if necessary so that it has a slight tackiness upon contact.

When adhering copper foil and resin-impregnated base material, it is convenient to laminate the adhesive-coated copper foil and the impregnated base material and to simultaneously perform the adhesion and curing of the impregnated resin to shorten the manufacturing process. After only the base materials are laminated and cured, the adhesive-coated copper foils may be superimposed and bonded by heating again.

EXAMPLES Hereinafter, the present invention will be described in detail by examples, but the present invention is not limited to these examples unless it departs from the gist of the present invention.

A separable flask (5000ml) equipped with a stirrer, a thermometer with a gas inlet tube, a reflux condenser, and a dropping funnel.
), methacrylic acid (35 g, 0.41 mol), ethyl acrylate (600 g, 6 mol), methyl ethyl ketone (600+r), dodecyl mercaptan (6 g)
was charged and heated to 75°C under a nitrogen atmosphere.

A solution of azobisisobutyronitrile (5 g) dissolved in 50 ml of methyl ethyl ketone was added from the dropping funnel so that the internal temperature was 80° C. or less. It was made to react at 75-80 degreeC for 8 hours. Thereafter, the temperature was raised to 180°C, and methyl ethyl ketone and a very small amount of unreacted ethyl acrylate were distilled off. The obtained polymer weighed 631 g and had a weight average molecular weight FF of 170,000.

In addition, in another reactor (2000 ml) with the same configuration as above, "Epicote 827J (trade name of epoxy resin)" was added.

(360 g, 1 mol), methacrylic acid (138 Fr, L, S mol), benzyldimethylamine (1,2 sr), and rosebenzoquinone (0.12 g) were heated at 120°C under a nitrogen atmosphere. 3
Allowed time to react.

The acid value of the reaction solution became almost zero, and a vinylation reagent containing an unsaturated group-containing epoxy resin was obtained.

Styrene monomer (iooog) was added and dissolved in this vinylation reagent, and this was added to the flask containing the polymer prepared previously. Furthermore, triphenylphosphine (5 g) and rosebenzoquinone (0.10 g) were added and heated, and 1
The reaction was carried out at 20°C for 4 hours. After the reaction, the unsaturated epoxy resin was about 13% of the amount before the reaction.

The thus obtained resin liquid containing the curable prepolymer has a non-volatile content of 53% by weight and a viscosity of 8.9 voids (at 25°C).
It was a yellowish brown liquid.

Separable flask (5000ml) equipped with stirrer, thermometer with gas inlet tube, reflux condenser, and dropping funnel.
Methyl ethyl ketone (1300 g) was added as a solution, followed by styrene (312 g, 3 mol), methacrylic acid (103.2 g, 1.2 mol), benzoyl peroxide (3 g), and dodecyl mercaptan (3.5 g).
was charged and reacted for 5 hours under nitrogen blowing conditions at 110 to 120°C, the polymerization rate of styrene was 78% and the polymerization rate of methacrylic acid was 83%.

The solvent and unreacted monomers were removed using a rotary evaporator to obtain a white polymer.

A 55% styrene solution containing the entire amount of this polymer was placed in the same apparatus as above, and then glycidyl methacrylate (142 g, 1 mol) and hydroquinone (0.3 g) were charged and reacted at 105 to 110°C for 3 hours. . The reaction rate of glycidyl methacrylate was 89%.

This resin liquid has a pale yellow color and a viscosity of 5.8 poise (25
℃).

A 1g separable flask equipped with a stirrer, a reflux condenser, a thermometer with a gas inlet tube, and a dropping funnel was charged with 1g of lauryl mercaptan and 0.2g of lauryl mercaptan, and a mixed monomer of styrene 18111[, 29g of 2-hydroxypropyl methacrylate] was added under reflux of benzene. drip.

After the dropwise addition was completed, benzene was refluxed for 16 hours, then 0.02 g of hydroquinone was added to stop the reaction, and the mixture was cooled to 60°C.

Furthermore, 300 g of benzene, 0.05 g of hydroquinone, 0.3 g of dibutyltin dilaurate, and 174 g of 2,4-tolylene diisocyanate were placed in a similar 1 g separable flask, and 2-hydroxy/di-3 diisocyanate was added at a temperature of 60°C. Drop propyl methacrylate steel g.

After the dropwise addition was completed, the reaction was continued at 60°C for 5 hours.

Add 124 g and continue the reaction at the same temperature for 5 hours.

Next, about 200 g of benzene was distilled off under reduced pressure of about 5001 Hg, 290 g of styrene was added, and about 200 mr@l was added.
Benzene is distilled off at 1 g.

The desired resin having a methacryloyl group in the side chain is obtained with a viscosity of 12.4 poise and a Hazen color number of 300.

In both cases, immediately after production, a roll coater is applied to the copper foil for approximately 40 minutes.
After coating to a thickness of 0 microns, heat treatment was performed at 100° C. for 5 minutes, and it was slightly sticky to the touch, and the next adhesion process was carried out within 30 minutes.

Examples 1 to 6 Kraft paper (10 cm x lO mark) with a basis weight of 135 g/I was soaked in an aqueous solution of Nikaledin S-305J (trade name 1 manufactured by Nippon Carbide Co., Ltd., methylolmelamine), squeezed with a roller, and dried at 120°C for 30 minutes. .

11.4 wt. This paper was placed in a flat plate and floated on an impregnating resin mixture having the composition shown in Table 1 to impregnate it with the liquid.

Six sheets of paper containing the impregnating resin mixture and one sheet of the copper foil with the above-mentioned electromagnetic agent were layered together, and two sheets of polyester film (-1i & 2) with a thickness of 100 microns were placed on both sides.

Lumirror (trade name) was placed and bonded using a heat press as the resin liquid hardened.

Table 1 shows the hot pressing conditions and the adhesive strength of the copper foil.

Comparative Example 1 A copper-clad laminate was made in the same manner as in Example 1, except that the adhesive-coated copper foil was replaced with a commercially available phenolic resin-based adhesive-coated copper foil (Mitsui Mining & Co., Ltd., trade name MK-56). Obtained. Table 1 shows the adhesive strength of the copper foil of the obtained copper-clad laminate.

(Left below) Effects As shown in Examples 1 to 6, adhesives using imidazole compounds can be impregnated with resin liquids made of various side chain double bond type resins under low pressure and short bonding conditions. It has been found that in a copper-clad laminate made of laminated copper foils, the copper foils have good adhesion.

By developing this adhesive strength, the copper-clad laminate can be used to produce a laminate for electrical circuits that can be used even under severe conditions.

Claims (1)

[Claims] In a method for manufacturing a copper-clad laminate in which a plurality of sheet-like substrates impregnated with a side chain double bond type resin are laminated and copper foil with an adhesive is laminated on one or both sides of the sheet, an imidazole compound is used as the adhesive. A method for manufacturing a copper-clad laminate, characterized by using an epoxy adhesive containing the following.