JPH0786709A - Laminated board for printed wiring board and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To increase the strength of the title laminated board used as the insulating sheet of a hard printed wiring board without substantially changing the other characteristics. CONSTITUTION:As a reinforcement member, a glass chopped strand is used in addition to a glass cloth. This glass chopped strand is mixed with a thermosetting resin varnish for impregnation and then a glass cloth is impregnated with this glass containing varnish to form a prepreg for the formation of the title laminated board by laminating step of the prepreg. Through these procedures, when the thermosetting resin is a condensed polycyclic polynuclear aromatic resin having a basic structure in which aromatic rings including condensation aromatic rings are crosslinked to each other, the heat resistance is further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated board for a printed wiring board, and more particularly to a laminated board for a printed wiring board having improved strength.

[0002]

2. Description of the Related Art A printed wiring board has a copper foil adhered to the surface of an insulating substrate and a wiring function is imparted to the copper foil by means such as imaging and etching. ) Type is roughly divided. The flexible printed wiring board has an insulating substrate made of a plastic film such as polyester or polyimide.

On the other hand, as an insulating substrate for a hard printed wiring board, a reinforcing base material made of paper or glass fiber is impregnated with a thermosetting resin and dried, and a predetermined number of the prepregs are stacked and heated and pressed. A laminated plate formed by a laminating method for molding is used. Laminates having a base material of paper are mainly used for consumer products such as home electric appliances, and laminates having a base material of glass fiber are mainly used for industries such as computers and electronic communication devices.

As a glass-based reinforcing base material for a laminated board used for this hard printed wiring board, a glass cloth suitable for lamination molding under pressure is exclusively used, and thermosetting used for impregnation of the glass cloth base material. Epoxy resin is mainly used as the conductive resin.

The conventional laminated board made of this glass cloth-epoxy resin has a bending strength of about 40 to 50 kgf / mm ^2, but it is suitable for high density and high multilayer wiring of printed wiring boards. Along with this, the number of cutting processes such as drilling processes is increasing, and the hole interval tends to be gradually narrowed. For this reason, the mechanical force and mechanical strain that the laminated plate receives increases, and in the conventional glass cloth-epoxy resin laminated plate, partial breakage and peeling between resin layers have come to be observed.

Further, with the increase in the density and the number of layers of wiring, the heat resistance of the printed wiring board, and thus the heat resistance of the laminated board, which is an insulating substrate therefor, is becoming more advanced, and the heat resistance of epoxy resin is higher than that of epoxy resin. The use of a resin having excellent properties has been demanded.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminate for a printed wiring board, which has a higher strength than the conventional glass cloth-epoxy resin laminate, and a method for producing the same. Another object of the present invention is to provide a laminated board for a printed wiring board which has improved heat resistance in addition to high strength.

[0008]

According to the present invention, a laminated board for a printed wiring board having high strength, characterized by containing glass cloth and glass chopped strands as a reinforcing material in a thermosetting resin. Will be provided.

In a preferred embodiment, the thermosetting resin is a condensed polycyclic polynuclear aromatic resin having a basic structure in which aromatic rings containing condensed aromatic rings are cross-linked through a methylene chain.
The laminated board of the present invention can be manufactured by impregnating glass cloth with a thermosetting resin containing glass chopped strands to form a prepreg, and laminating and molding the prepreg.

[0010]

As a means for improving the strength of laminated plates, it is possible to increase the content of glass fibers. However, the unit weight of the glass cloth used as a reinforcing material (weight per unit area) is increased and the number of laminated prepregs is changed. May have a great influence on properties other than the strength of the entire laminate.

In the laminated board for a printed wiring board of the present invention, glass chopped strands are contained in addition to the glass cloth to increase the glass fiber content as a whole. However, the weight of the glass cloth and the number of laminated prepregs are increased. Does not need to be changed compared to the conventional one. Therefore, higher strength can be obtained as compared with the conventional laminated plate using only the glass cloth as a reinforcing material, but other characteristics do not change significantly.

When the glass chopped strands are mixed in the glass cloth, the handling of the cloth during the subsequent impregnation operation becomes troublesome. Therefore, the glass chopped strands are mixed in the thermosetting resin used for impregnation of the glass cloth and the glass chopped strands are mixed. By impregnating the contained resin into the glass cloth,
It is preferably introduced into the laminate.

The shape of the glass chopped strands is not particularly limited, but it is usually a length of several millimeters. The mixing amount of the glass chopped strands is preferably in the range of 5 to 20 wt% with respect to the total weight of the laminated plate. Both glass chopped strands and glass cloth are made of non-alkali glass such as E glass and T glass.

On the other hand, as the thermosetting resin used for the impregnation, various thermosetting resins such as epoxy resin which has been conventionally used, phenol resin, unsaturated epoxy resin and the like can be used.

However, when particularly high heat resistance is required, a condensed polycyclic polynuclear aromatic resin having a basic structure in which a large number of aromatic rings including condensed aromatic rings are crosslinked through a methylene chain is impregnated. It is preferable to use This resin is
It has a long-term heat resistance of more than 250 ° C, and exhibits excellent long-term heat resistance that exceeds not only epoxy resins but also polyimide resins known as heat-resistant resins. Therefore, by using this resin for impregnation, it is possible to impart not only high strength but also high heat resistance to the obtained laminated plate.

The condensed polycyclic polynuclear aromatic resin is a raw material containing a condensed ring aromatic compound such as naphthalene as a main component,
A thermosetting resin obtained by reacting a cross-linking agent composed of an aromatic compound having at least two hydroxymethyl groups or halomethyl groups in the presence of an acid catalyst. Since the raw material is inexpensive, it can be supplied inexpensively in the future. The reaction between the raw material and the cross-linking agent is stopped in the state of a semi-cured product (B stage) and used for impregnation, as in the case of a normal thermosetting resin. When this resin is further heated, it becomes an insoluble and infusible thermosetting product, and therefore a curing agent is not required for thermosetting. The condensed polycyclic polynuclear aromatic resin is described in detail in, for example, Japanese Patent Application No. 5-180284.

To impregnate the resin, the thermosetting resin to be used is dissolved in a suitable organic solvent to prepare a varnish. When a curing agent is required for thermosetting like an epoxy resin, an appropriate curing agent or curing accelerator is also dissolved in this varnish. In the present invention, glass chopped strands are further added to this varnish, mixed and dispersed uniformly. A glass cloth is immersed in a thermosetting resin varnish containing the glass chopped strands for impregnation, and then dried to remove the solvent to obtain a prepreg.

If necessary, this prepreg is cut into an appropriate length, and a predetermined number of the prepregs are stacked to form a laminate.
By laminating by heating under pressure with a laminating press to cure the resin, the laminated plate of the present invention containing both glass cloth and glass chopped strands as a reinforcing material can be obtained. The molding conditions at this time may be appropriately selected according to the thermosetting resin used.

For example, when the thermosetting resin is the aforementioned condensed polycyclic polynuclear aromatic resin, the molding conditions are generally temperature.
100 ~ 300 ℃, pressure 5 ~ ²⁰⁰ kgf / cm ² , holding time 10 ~
Within 300 minutes.

When the laminated molding is performed by laminating the copper foil on both sides or one side of the laminate, the copper foil is also adhered at the same time to produce a copper-clad laminate. Usually, the copper-clad laminate is often directly manufactured in this manner. A hard printed wiring board is manufactured by further forming wiring on the obtained copper foil of the copper-clad laminate by drilling, imaging and etching techniques.

The method of manufacturing the printed wiring board described above is the same as the conventional method except that glass chopped strands are mixed with the thermosetting resin varnish. According to the present invention, in addition to the glass cloth, by mixing the glass chopped strands in the resin used for impregnation, the content of the glass fibers can be increased by the amount mixed in the resin, and the laminated plate The strength, especially the bending strength, is significantly improved. Since this increase in strength is achieved without changing the basis weight of the glass cloth and the number of laminated prepregs, other characteristics such as insulation characteristics, water absorption, and solder heat resistance do not substantially deteriorate.

[0022]

EXAMPLE A mixture of 100 parts by weight of naphthalene, 173 parts by weight of 1,4-dihydroxybenzene, and 8.3 parts by weight of β-naphthalenesulfonic acid as a catalyst was heated at 110 ° C. for 3 hours.
By stirring and reacting, a semi-cured condensed polycyclic polynuclear aromatic resin was obtained. This resin had a brown transparent appearance, a melt viscosity at 70 ° C. of 16,500 cP, and a number average molecular weight of 580.

This thermosetting resin is dissolved in dioxane,
Glass chopped strand (made by Nitto Boseki
A resin varnish having a resin content of 60% by weight, a glass content of 10% by weight, and a varnish viscosity of 50 to 50 cP was prepared by mixing CS 3E227, a cut length of 3 mm, and a filament diameter of 10 μm).

Using this glass-containing resin varnish, a glass cloth (T glass cloth manufactured by Nitto Boseki Co., Ltd., basis weight 105 g / m ² , density
40 pieces / 25mm) and by drying at 100 ℃,
I got a prepreg. The total glass content in this prepreg was 56% by weight. 2 sheets of electrolytic copper foil are stacked by stacking the obtained prepregs in the number of sheets that can produce a 1.6 mm molded body.
100 kgf / cm ² when sandwiched between (35 μm thick)
A laminated plate having a thickness of about 1.6 mm was obtained by hot pressing at 230 ° C. for 50 minutes under a pressure of 1.

Table 1 shows the results of measuring the bending strength of this laminated plate based on the method specified in JIS C6481. For comparison, a laminate obtained in the same manner as above, except that the glass chopped strands were not mixed in the resin varnish.
The bending strength of (Comparative Example) is also shown.

[0026]

[Table 1]

[0027]

According to the present invention, bending strength can be remarkably improved by mixing glass chopped strands in a resin for impregnation.

Claims (3)

[Claims] 1. A laminate for a printed wiring board, comprising a glass cloth and a glass chopped strand as a reinforcing material in a thermosetting resin. 2. The laminate according to claim 1, wherein the thermosetting resin is a condensed polycyclic polynuclear aromatic resin having a basic structure in which aromatic rings containing condensed aromatic rings are cross-linked through a methylene chain. 3. A laminated sheet according to claim 1, wherein a glass cloth is impregnated with a thermosetting resin containing glass chopped strands to form a prepreg, and the prepreg is laminated and molded. Method.