JP3362804B2 - Method for producing copper foil with adhesive and copper-clad laminate for multilayer printed wiring board using this copper foil with adhesive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil with an adhesive and a method for producing a copper clad laminate for a multilayer printed wiring board using the copper foil with an adhesive.

[0002]

2. Description of the Related Art Copper-clad laminates for multilayer printed wiring boards are
One or two or more inner layer circuit boards and outer layer materials are bonded and integrated. The outer layer material is a double-sided or single-sided copper-clad laminate or a copper foil. The outer layer copper foil is processed into a circuit and the parts are mounted and incorporated into electrical equipment. In recent years, devices have become smaller, and copper foil tends to be used as an outer layer material.

A glass base prepreg has been used for interlayer adhesion of constituent materials. The glass cloth which is the base of the prepreg serves as a volumetric neck, and electrolytic corrosion and processing along the glass fiber surface. Due to problems such as properties, the constituent materials have come to be adhered with an adhesive film without a base material.

On the other hand, a paper-based phenol prepreg and a copper foil are bonded to the phenol laminate using a copper foil with an adhesive. As this adhesive, an epoxy resin modified with melamine resin, phenol resin, butyral, isocyanate or the like is used.

[0005]

It would be convenient if the copper foil with an adhesive used in a phenolic laminate could be used in the production of a copper clad laminate for a multilayer printed wiring board (hereinafter simply referred to as a multilayer board). is there. However, the copper foil with adhesive used for the phenolic laminate has poor flowability of the adhesive resin, and the unevenness caused by forming the circuit on the inner layer circuit board cannot be filled, so the heat resistance is poor. ,
In addition, the inner layer peeling strength is extremely low, and therefore cannot be used. The present invention provides an adhesive-bonded copper foil for producing a copper-clad laminate for a multilayer printed wiring board, which has good circuit filling properties and heat resistance when directly laminated on an inner-layer circuit board and heated and pressed. The purpose is to

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies on various adhesives with respect to resin flowability during heating and pressurizing and properties of a multilayer board at the time of completing the present invention. It was That is, the present invention, on one surface, a phenoxy resin, butyral, one or more kinds of higher fatty acids, epoxidized polybutadiene, a first adhesive layer mainly composed of a melamine resin and an epoxy resin is formed, and a phenoxy resin is formed thereon. It is characterized by a copper foil with an adhesive formed by forming a second adhesive layer containing at least one of butyral, higher fatty acid, epoxidized polybutadiene and epoxy resin.

As the epoxy resin, both the first adhesive layer and the second adhesive layer are bisphenol A diglycidyl ether, cresol novolac type epoxy resin, phenol novolac epoxy resin, bisphenol A novolac type epoxy resin, acrylic modified epoxy resin. Generally commercially available epoxy resins can be used. It may be a bromine-containing type having flame retardancy. However, the bromine content is preferably 30% by weight or less. If it exceeds 30% by weight,
The heat resistance is significantly reduced.

The composition ratio of the first adhesive layer is epoxy resin 1
5 to 100 parts by weight of melamine resin, relative to 00 parts by weight,
25 to 300 parts by weight of one or more of phenoxy resin, butyral, higher fatty acid, and epoxidized polybutadiene. When the amount of the melamine resin is less than 5 parts by weight, the heat resistance is poor, and when the amount of the melamine resin exceeds 100 parts by weight, the adhesive strength is low and the necessary peeling strength cannot be obtained. If the amount of one or more of phenoxy resin, butyral, higher fatty acid and epoxidized polybutadiene is less than 25 parts by weight, the adhesive strength will be weak, and if it exceeds 300 parts by weight, the heat resistance will be poor.

The composition ratio of the second adhesive layer is epoxy resin 1
50 parts by weight of one or more of phenoxy resin, butyral, higher fatty acid, and epoxidized polybutadiene per 100 parts by weight.
~ 300 parts by weight. Phenoxy resin, butyral,
5 or more of one or more of higher fatty acid and epoxidized polybutadiene
If the amount is less than 0 parts by weight, the unevenness of the circuit cannot be filled, and if it exceeds 300 parts by weight, the heat resistance is poor.

The total thickness of the adhesive layer must be 10 μm or more. When the thickness is 10 μm or less, the unevenness of the circuit cannot be filled. The upper limit of the thickness is not particularly limited, but if the thickness becomes thick, it becomes difficult to form the adhesive layer, so that a too thick one is not preferable and is not necessary. Generally, about 300 μm is sufficient.

In the copper foil with adhesive of the present invention, the materials of the first and second adhesive layers are dissolved in an alcohol or ketone solvent to form a varnish, which is applied to the copper foil surface and dried. It is manufactured by semi-curing a resin. The amount of solid resin in the varnish is optimally 15 to 70% by weight.

The adhesive-attached copper foil thus obtained is laminated on the inner layer circuit board having the circuit surface roughened and heated and pressed to form a multilayer board. The roughening of the circuit surface is performed by a known method such as an oxidation treatment, an oxidation treatment and a reduction treatment. The heating and pressing may be performed by multi-step pressing or roll forming.

The multilayer board thus obtained is drilled or laser-drilled, copper-plated, and then etched to obtain a printed wiring board. The printed wiring board thus obtained may be further laminated as an inner layer circuit board to form a high multilayer board.

[0014]

Since the resin of the second adhesive layer does not contain a melamine resin, it has a small viscosity and a good fluidity when the semi-cured adhesive is heated. When cured without melamine, the heat resistance is inferior, but the melamine resin in the first adhesive layer migrates into the second adhesive layer during the heat curing process, so the heat resistance of the entire adhesive layer does not decrease. .

[0015]

EXAMPLE 100 parts of 80% modified butyral cresol novolac epoxy resin (part by weight, the same hereinafter) and 10 parts of melamine resin were mixed and dissolved in methyl ethyl ketone.
The varnish for the first adhesive layer was used. Tetrabromobisphenol A on 100 parts of 50% modified epoxidized polybutadiene
40 parts of diglycidyl ether and 20 parts of bisphenol A novolak were mixed and dissolved in methyl ethyl ketone.
The varnish for the second adhesive layer was used. The varnish for the first adhesive layer is applied to a silanized copper foil so that the thickness after drying is 15 μm and dried, and the varnish for the second adhesive layer is applied and dried to obtain a total adhesive thickness of 50 μm. A copper foil with an adhesive was obtained. Next, the above-mentioned copper foil with an adhesive is placed on the upper and lower sides of a glass-based epoxy resin double-sided printed wiring board that has undergone circuit processing and has a roughened surface, and is heated and pressed at 170 ° C. and 4 MPa for 80 minutes to enter the inner layer circuit A copper-clad laminate was obtained.

Comparative Example Adhesion of 100 parts of 50% butyral-modified cresol novolac epoxy resin, 20 parts of melamine resin, and 20 parts of phenolic resin on the upper and lower sides of a glass-based epoxy resin double-sided printed wiring board whose surface has been roughened by circuit processing. After placing the agent on it, stacking silanized copper foil at 170 ° C for 4
It was heated and pressed at 80 MPa for 80 minutes to obtain a copper-clad laminate with an inner layer circuit.

With respect to the multi-layered copper clad laminate containing inner layers obtained as described above, the peeling strength in the receiving state (A), C
-Heat resistance after 96/40/90 treatment (observation of blisters when floated on solder at 260 ° C), circuit filling property, C-1
The electrolytic corrosion resistance after 000/85/90 treatment and the flame retardancy in the accepted state (A) were examined according to JIS. The results are shown in Table 1.
Shown in. The electrolytic corrosion resistance was measured by providing through holes with a diameter of 0.9 mm at a pitch of 350 μm and applying a DC voltage of 100 V between the through holes.

[0018]

[Table 1]

[0019]

According to the present invention, substrateless bonding between constituent materials of a multilayer board can be realized without impairing the heat resistance and other characteristics of the multilayer material.

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-51-145865 (JP, A) JP-A-1-172479 (JP, A) JP-A-4-216813 (JP, A) JP-A-59- 213196 (JP, A) JP 62-202589 (JP, A) JP 2-1789 (JP, A) JP 3-244194 (JP, A) JP 7-26242 (JP, A) JP-A-5-163479 (JP, A) JP-A-7-106752 (JP, A) JP-A-6-240213 (JP, A) JP-A-5-291741 (JP, A) JP-A-5-162231 (JP, A) JP-B-35-11734 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 3/38 C09J 7/02 H05K 3/46

Claims (2)

(57) [Claims] 1. A first adhesive layer composed mainly of phenoxy resin, butyral, higher fatty acid, epoxidized polybutadiene, melamine resin and epoxy resin is formed on one surface of the phenoxy resin, butyral. ,
A copper foil with an adhesive formed by forming a second adhesive layer mainly containing one or more of higher fatty acid, epoxidized polybutadiene and epoxy resin. 2. A copper foil with an adhesive according to claim 1 is laminated on an inner layer circuit board so that the adhesive is in contact with the inner layer circuit board,
A method for producing a copper-clad laminate for a multilayer printed wiring board, which comprises heating and pressing.