JPH0757494B2 - Laminated board manufacturing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing a laminate, and more particularly to pressure control for press molding.

BACKGROUND OF THE INVENTION Epoxy resin laminates used for consumer and industrial purposes such as electronic and electrical equipment are usually prepregs obtained by impregnating a base material such as cloth, paper or nonwoven fabric with epoxy resin varnish and drying. Laminated structure in which one or a plurality of the above are laminated, or a metal foil such as copper foil is laminated on the laminated structure and sandwiched in a mirror surface plate, and a predetermined heat and pressure is applied by a multi-stage hot press for forming a laminated plate. Conventionally, a method of producing a large number of laminated plates at one time under the conditions has been practiced.
Here, in the press molding step of performing the heating and pressurizing, a conventional method, that is, under atmospheric pressure (760 mmHg
The method of molding under (below) (hereinafter referred to as normal pressure molding) and the method of molding under vacuum or reduced pressure (hereinafter referred to as reduced pressure molding) are known.

Problems to be Solved by the Invention In the vacuum molding of the conventional method, since press molding for heating and pressurizing the laminated structure is performed in vacuum or under reduced pressure, lamination caused by gas and voids in the laminated structure Reduces defective phenomena such as plate bubbles, voids, and gas fog around the laminate
Or, by being eliminated, the molding pressure is a constant pressure equal to or lower than the molding pressure of normal pressure molding, for example, a unit pressure of 5 to 15 kg / cm ²
Molding was performed at a very low molding pressure.

Therefore, the conventional laminate obtained by vacuum molding does not show the phenomenon of voids, bubbles, etc., but in the case of a laminate without metal foil attached integrally, the surface smoothness is In the case of, the metal foil peel strength is insufficient, and when the laminated structure is formed by using different prepregs, the adhesive force between the layers is not sufficient, which may cause an increase in the fluctuation range of the above-mentioned characteristics in the laminated plate. There was a problem such as.

An object of the present invention is to provide a laminate having excellent interlayer adhesion, surface smoothness, and metal foil peel strength in the production of the laminate by vacuum molding.

Means for Solving the Problems The present invention has been made to achieve the above object,
In a vacuum molding of a laminated plate for producing a laminated plate by heating and pressurizing a prepreg and a metal foil placed on the surface thereof under vacuum or reduced pressure, the forming pressure is increased during the heat forming Is. In the method of the present invention, the time at which the molding pressure is increased is the time at which the resin in the prepreg of the laminated structure has melted and started to cure.

Action The present invention has the above-described characteristics, and thus has the same effect as that of the conventional vacuum molding, that is, it reduces or reduces defective phenomena such as bubbles in the laminate, voids, and gas fog around the laminate. Not only does it disappear, but by increasing the molding pressure during heat molding, the surface smoothness of the laminated plate,
Laminated board properties such as copper foil (metal foil) peel strength improvement and adhesion strength between different prepregs are superior to those obtained by conventional atmospheric molding and vacuum molding, and lamination of these characteristics The fluctuation range within the plate can be reduced.

Examples In the present invention, the resin used for the prepreg is not limited to epoxy, but is any resin that can be used for a laminated plate such as melamine and phenol, polyamide and polyimide polyester. Further, the base material that is impregnated with a resin to form a prepreg is usually a material such as paper, cloth, non-woven fabric, etc. that is used for laminate molding. The metal foil is not limited to the copper foil.

Embodiments of the present invention will be described in detail.

Example 1 A glass cloth was coated and impregnated with an epoxy resin for FR-4, dried by heating, and had a resin content of B stage of 42% by weight, size,
A prepreg of 1050 mm × 1050 mm was obtained. The size of 1070mm × 1070mm, thickness
18 μm copper foil is placed to form one set of laminated structure, and the prepreg structure and the stainless specular plate are alternately combined on the carrier plate so that 12 copper-clad laminated plates can be obtained from one press step. Up to 12 sets. Next, five sheets of kraft paper (thickness 0.15 mm) were formed on the upper and lower sides to form a cushion material for molding, and an upper plate was placed on the upper cushion material to form one step of press molding. Thirty stages were constructed in the same manner as this one stage and were inserted between the press heating plates.

Next, using a vacuum pump, with a reduced pressure of 50 mmHg, heating plate temperature 175 ° C, molding initial pressure 10 kg / cm ² , late molding pressure 30 kg / cm
^2. Heat and pressure molding was performed under the conditions of heating time of 100 minutes and cooling time of 40 minutes to obtain a copper-clad laminate having a thickness of 1.6 mm. The point where the pressure rises to the latter-stage pressure is when the temperature of the prepreg near the heating plate reaches 110 ° C. (gelling point of the prepreg resin).

Example 2 An initial molding pressure of 10 kg / cm ² , a late molding pressure of 50 kg / cm ² , and other conditions were the same as in Example 1 to obtain a 1.6 mm thick copper clad laminate.

Example 3 A 1.6 mm thick copper clad laminate was obtained in the same manner as in Example 1 except that the initial pressure for molding was 10 kg / cm ² , the latter pressure for molding was 70 kg / cm ² , and other conditions were the same.

Example 4 A copper clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1 except that the pressure was reduced to 300 mmHg.

Example 5 A 1.6 mm thick copper clad laminate was obtained in the same manner as in Example 4 except that the initial pressure for molding was 10 kg / cm ² , the latter pressure for molding was 50 kg / cm ² , and other conditions were the same.

Example 6 An initial molding pressure of 10 kg / cm ² , a latter molding pressure of 70 kg / cm, and other conditions were the same as in Example 4 to obtain a copper-clad laminate having a thickness of 1.6 mm.

Conventional Example 1 Using the same epoxy-glass cloth prepreg as in Example 1, under normal pressure (atmospheric pressure of 760 mmHg), heating plate temperature 175 ° C., molding initial pressure 10 kg / cm ² , late molding pressure 70 kg / cm ² ( Molding pressure rise point is the same as in Example 1), heating and pressure molding is performed under conditions of heating time of 100 minutes and cooling time of 40 minutes, and a thickness of 1.6 mm.
To obtain a copper-clad laminate.

Conventional Example 2 As in Example 1, the pressure was reduced to 50 mmHg, except that the molding pressure was
A copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1 except that the pressure was kept constant at 10 kg / cm ² .

Conventional Example 3 A copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Conventional Example 2 except that the molding pressure was kept constant at 20 kg / cm ² .

Conventional Example 4 A 1.6 mm-thick copper-clad laminate was obtained in the same manner as in Conventional Example 2 except that the depressurized state was 300 mmHg.

Conventional Example 5 A copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Conventional Example 4 except that the molding pressure was kept constant at 20 kg / cm ² .

In the above, Examples 1 to 6 and Conventional Examples 1 to 5 have been described for FR-4 type epoxy copper clad laminates. However, the epoxy resin-glass nonwoven fabric prepreg is used as the core material, and the epoxy-glass cloth prepreg is used as the surface. The composite copper-clad laminate used as the material will be described.

Example 7 A glass non-woven fabric is coated and impregnated with an epoxy resin for CEM-3,
Heat-dried B-stage resin content 60% by weight, size
A 1050 mm x 1050 mm epoxy glass nonwoven fabric prepreg was obtained. Example 1 was prepared on both sides of which four prepregs were superposed.
The epoxy-glass cloth prepregs prepared in Step 1 were stacked one by one to make a total of six. Furthermore, on both sides, the size is 1070 mm ×
A copper foil having a thickness of 1070 mm and a thickness of 18 μm was arranged to form one set, and thereafter, in the same manner as in Example 1, a 1.6 mm-thick composite copper-clad laminate was obtained.

Example 8 A molding copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 7 except that the molding initial pressure was 10 kg / cm ² and the molding late pressure was 50 kg / cm ² .

Example 9 A composite copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 7 except that the molding initial pressure was 10 kg / cm ² , the molding late pressure was 70 kg / cm ² .

Conventional Example 6 With the same prepreg structure as in Example 7, normal pressure (atmospheric pressure 760 m
In the same manner as in Conventional Example 1, a 1.6 mm-thick composite copper-clad laminate was obtained under mHg).

Conventional Example 7 As in Example 7, the pressure was reduced to 50 mmHg, but the molding pressure was kept at a constant pressure of 20 kg / cm ² , and thereafter, the same method as in Example 7 was used to coat the composite copper with a thickness of 1.6 mm. A laminated board was obtained.

Regarding the copper-clad laminates produced in Examples 1 to 9 and Conventional Examples 1 to 7, the plate thickness, the presence or absence of voids, warpage, twisting, resin flow, copper foil peel strength, and the composite copper-clad laminates, The adhesive strength between the glass cloth layer and the glass nonwoven fabric layer was evaluated. The results are shown in Table 1.

Effects of the Invention The effects of the present invention will be described below.

(1) It has the same effect as the conventional reduced pressure molding, that is, the effect of eliminating bubbles and voids in the laminate.

(2) Since the pressure is increased during the heating and pressurization of the vacuum molding, especially when the resin of the prepreg is melted and starts to be cured, (1)
In addition to the effect of item, the peel strength of the copper foil (metal foil) is improved as compared with the conventional one.

(3) In the case of the composite laminated plate, the adhesive strength between different kinds of laminated materials (prepregs) such as the interlayer adhesion strength between different kinds of prepregs such as the glass cloth layer and the glass non-woven fabric layer is improved compared to the conventional vacuum molding, and is excellent. .

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Claims (1)

[Claims] 1. A method for forming a laminated sheet by heating and pressing a prepreg and a metal foil placed on the surface thereof under reduced pressure, at the time when the resin of the prepreg is melted and starts to cure during the heating and pressurizing. A method for manufacturing a laminate, which comprises increasing a molding pressure.