JPH10272721A - One-side copper-clad laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce warp after a heat treatment by selectively combining sheet base material so as to satisfy a specific formula in both elastic-modulus of the material of a layer in contact with a copper foil and elastic modulus of a sheet base material of other layer than that in both lateral and longitudinal directions of the material. SOLUTION: The one-side copper clad laminate is obtained by selectively combining sheet materials so as to satisfy a formula of 0.1<=(b-a)<=1.5 in both lateral and longitudinal directions of the material of a and b, where elastic modulus of the material of a layer in contact wit a copper foil is aG Pa and elastic modulus of the material of the other layer is bG Pa. When the foil is disposed at the side where the material having small elastic modulus is disposed, a force for generating warp of the foil surface bent in a convex manner is balanced with that for generating warp of the material having small elastic modulus at the side bent in a concave manner, and hence the warps can be reduced as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a single-sided copper-clad laminate made of paper.

[0002]

2. Description of the Related Art A single-sided copper-clad laminate made of paper is excellent in punching workability and drilling workability and is inexpensive. Therefore, it is in great demand as a printed wiring board material for consumer electronic equipment. A single-sided copper-clad laminate based on paper is manufactured by laminating a predetermined number of prepregs based on paper, laminating copper foil on one side thereof, and applying heat and pressure. And the prepreg,
It is obtained by impregnating and drying a varnish of a thermosetting resin on a paper substrate. A standard single-sided copper-clad laminate as a printed wiring board material for consumer electronic devices is a combination of eight prepregs and a 35 μm-thick copper foil having a total thickness of 1.6 mm.

[0003]

A conventional single-sided copper-clad laminate has a warp caused by an unbalanced layer structure in which copper foil is provided only on one side, and in particular, a warp when heated. However, there is a drawback that the problem occurs. In single-sided copper-clad laminates, silver paste printing for forming a circuit using silver paste or silver through holes for connection by embedding silver paste are frequently used. A copper paste may be used instead of the silver paste. However, when a silver paste is used, a heat treatment step (normally at 150 to 160 ° C.,
(2 to 3 times drying for 0 to 40 minutes) is essential. The same applies to copper paste. Accordingly, there has been a great demand for a single-sided copper-clad laminate having a small warpage when subjected to a heat treatment.

An object of the present invention is to provide a single-sided copper-clad laminate having a small warpage when subjected to a heat treatment.

[0005]

According to the present invention, when the elastic modulus of the paper base in contact with the copper foil is aGPa and the elastic modulus of the other paper base is bGPa, a and b are the paper bases. This is a single-sided copper-clad laminate obtained by selecting and combining paper base materials so as to satisfy the following equation 2 in both the vertical and horizontal directions of the material.

## EQU2 ## 0.1 ≦ ba ≦ 1.5

The operation of the present invention will be described below. Although the thermosetting resin shrinks due to the heat treatment, the copper foil does not shrink, so if the elastic modulus of the paper base is all the same, the shrinkage of the copper foil and the opposite surface will increase, and the copper foil will shrink. Is generated. Assuming a case where a paper base having a small elastic modulus is arranged on one side as in the present invention and copper is not peeled off, the side on which the paper base having a small elastic modulus is arranged has a small elastic modulus, so The force against the shrinkage of the surface decreases, and the shrinkage of this surface increases. Therefore, a warp is generated such that the paper base having a low elastic modulus becomes concave. Then, if there is a copper foil on the side where the paper base material with a small elastic modulus is placed, the force to generate a warp with a convex copper foil surface and the side on which the paper base material with a small elastic modulus is placed (copper is And the force that generates a warp such that the warp becomes concave, so that the warp can be reduced as a whole.

In the equation (2), the elastic modulus of the paper base is 0.1.
When 1> ba, the force for generating a warp that is concave on the side where the copper foil is located is small, and there is no effect of reducing the warp. When 1.5 <b−a, the force for generating a warp that is concave on the side where the copper foil is located is too large. When 0 = ba, the elastic modulus is the same, and when 0> ba, the elasticity of the copper-foiled paper substrate increases. That is not. From this, the above-mentioned a and b
It is more preferable to select and combine paper base materials so that the formula (3) is satisfied in both the vertical and horizontal directions of the paper base material.

(Equation 3) 0.2 ≦ ba ≦ 0.8

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Paper base materials used in the present invention include kraft paper, which is known as a material for producing copper-clad laminates.
Linter paper or the like can be used. The elastic modulus of the paper substrate can be adjusted by changing the conditions at the time of paper substrate production, that is, changing the type of pulp, the papermaking method, and the like.

As the thermosetting resin, a phenol resin,
Thermosetting resins conventionally used as matrix resins for paper-base laminates, such as melamine resins, epoxy resins and unsaturated polyester resins, can be used. Among the thermosetting resins, a phenol resin is most widely used.

The phenolic resin includes a resol resin and a novolak resin. A paper base laminate usually contains a resol resin obtained by reacting a phenol and an aldehyde in the presence of an alkali catalyst. Used.

Aldehydes used in the synthesis of the phenolic resin include formaldehyde, paraformaldehyde, acetaldehyde, paraacetaldehyde, butyraldehyde, octylaldehyde, benzaldehyde and the like. Generally, formaldehyde or paraformaldehyde is used.

It is preferable to use a resol resin modified with a drying oil in order to impart flexibility to the laminate and improve punching workability. A resole resin modified with a drying oil can be obtained by reacting a phenol and a drying oil in advance in the presence of an acid catalyst, and then reacting an aldehyde in the presence of an alkali catalyst. As drying oils, tung oil, linseed oil, dehydrated castor oil,
Oitichika oil or the like is used.

[0013] The paper base laminate is prepared by impregnating and drying a varnish obtained by dissolving a resole resin in a solvent into a prepreg,
A predetermined number of the prepregs are stacked, and the temperature is 150 to 180.
It is manufactured by heating and pressing at a temperature of 7 ° C. and a pressure of 7 to 15 MPa for 60 to 120 minutes. A copper-clad laminate used as a material for a printed wiring board is manufactured by combining a prepreg and a copper foil and applying heat and pressure. As a solvent when the phenol resin is used as a varnish, toluene, methanol, methyl ethyl ketone, 2-methoxyethanol, acetone, styrene and the like are used. If necessary, a plasticizer and a flame retardant are added to the varnish to impart plasticity and flame retardancy to the phenol resin laminate.

Generally, the affinity between the cellulose fiber and the resole resin constituting the paper base is not good. Therefore, it is preferable to previously attach a water-soluble phenol resin or a water-soluble melamine resin to the paper substrate.

[0015]

【Example】

Preparation of water-soluble phenolic resin varnish 1 mol of phenol was charged into a reaction vessel, and 37% by weight was added thereto.
Formalin was added in an amount equivalent to 1.2 mol as formaldehyde, and then a 30% by weight aqueous solution of trimethylamine was added in an amount equivalent to 0.4 mol of trimethylamine, and reacted at 70 ° C. for 6 hours to obtain a water-soluble phenol resin varnish.

Preparation of Tung Oil-Modified Phenolic Resin Varnish 860 g of tung oil, 1000 g of meta-cresol, 1000 g of phenol and 1 g of paratoluenesulfonic acid were charged into a reaction vessel and reacted at 110 ° C. for 2 hours.
The reaction was continued at 80 ° C., and the reaction product was dehydrated and concentrated under reduced pressure under a reduced pressure when the gelation time of the reaction product (meaning the gel time on a hot plate at 160 ° C., the same applies hereinafter) became 5 minutes. A tung oil-modified phenolic resin varnish having a gelling time adjusted to 3 minutes was obtained.

Preparation of Prepreg The kraft paper A shown in Table 1 was impregnated and dried with the water-soluble phenolic resin varnish obtained above so that the solid content after drying was 15% by weight. Tung oil-modified phenolic resin varnish was impregnated and dried so that the total amount of adhesion with the water-soluble phenolic resin was 50% by weight.
Was prepared. Similarly, prepreg B was produced using kraft paper B, and prepreg C was produced using kraft paper C.

[0018]

[Table 1]

EXAMPLE 1 Seven prepregs B were stacked, one prepreg A was stacked thereon, and one copper foil with an adhesive having a thickness of 35 μm was stacked thereon, and heated and pressed at 170 ° C. and 11 MPa. Thus, a single-sided copper-clad laminate having a thickness of 1.6 mm was produced.

The obtained single-sided copper-clad laminate was 300 × 200
mm, and a hole (diameter: 0.6 mm) for a silver paste through hole was formed in the hole by a drill with a hole interval of 2.0 mm. Fill the hole with silver paste,
After drying at a temperature of 160 ° C. for 30 minutes, a silver jumper was printed using the same silver paste and dried at a temperature of 160 ° C. for 30 minutes. The silver paste was manufactured by Fujikura Kasei Co., Ltd.
Dotite XA-209 (trade name) was used. Thereafter, the copper foil was placed on a flat plate so that the copper foil faced downward, and the maximum jump amount of the four corners was measured.
3 mm.

COMPARATIVE EXAMPLE Seven prepregs C were stacked, and one prepreg A was stacked thereon. A single-sided copper-clad laminate having a thickness of 1.6 mm was produced in the same manner as in Example 1. Thereafter, the maximum jump amount of the four corners was measured in the same manner as in Example 1, and it was 4.2 mm.

[0022]

According to the present invention, a single-sided copper-clad laminate having a small warp after the heat treatment can be obtained.

Claims (1)

[Claims] 1. The elastic modulus of a paper base of a layer in contact with copper foil is a
GPa, and the elastic modulus of the paper base material of the other layers is bGPa.
A single-sided copper-clad laminate obtained by selecting and combining paper base materials such that a and b satisfy the following equation 1 in both the vertical and horizontal directions of the paper base material. ## EQU1 ## 0.1 ≦ ba ≦ 1.5