JPH08300564A - Manufacture of laminate - Google Patents

Abstract

PURPOSE: To provide good warping properties, dimension stability and the like by laminating two prepregs prepared by heat drying a laminate formed by overlapping a glass fiber non-woven cloth on a varnished surface applying thermosetting resin varnish on one face of a paper base. CONSTITUTION: Thermosetting resin varnish 2 is applied on the upper face of a continuous base 1 in the given film thickness by a coater 3. Although varnish 2 can be used as it is, if an inorganic filler irradiated the punching properties and dimension stability are improved, and through-hole reliability in also improved, and thermal expansion coefficient in the Z direction gets smeller. Resin varnish 2 is applied to the continuous base and then a glass non-woven cloth 4 is overlapped, while resin varnish is applied from the rear face. Then heat drying is carried out through a drying device 6 and thermosetting resin impregnated prepregs composed of the glass non-woven cloth overlapped on the continuous base are prepared. Two prepregs thus prepared are overlapped with the glass non-woven cloth 4 on the inner side and heat and pressure molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated board suitable for a printed circuit board used in telecommunications, electronic equipment, communication equipment and the like.

[0002]

2. Description of the Related Art Consumer electronic devices have become smaller and more sophisticated, and as a printed circuit board used for them, glass nonwoven fabric is used as an intermediate layer base material and glass woven fabric is used as a surface layer base material. A laminate (hereinafter referred to as a composite laminate) impregnated with a resin and heat-pressed is used. Recently, such composite laminates have been required to have the same punching workability and lower cost as those of the paper-based phenolic resin laminates conventionally used in this field.

Further, in the field of industrial electronic equipment, composite laminated plates without glass woven cloth or with a reduced amount of glass cloth have come to be used because of the need for cost reduction. It is inferior to the woven fabric substrate laminate in various points, and it has been required to have the same dimensional change and small warpage as those.

[0004]

In order to meet the various demands for composite laminates as described above, it is considered to use a resin varnish containing a single glass fiber without using a glass nonwoven fabric as an intermediate layer base material. However, although the dimensional change and the warp are improved, there are various problems in manufacturing and they have not yet been put into practical use. On the other hand, it has been studied to reduce the proportion of glass woven fabric or non-woven fabric for cost reduction, but cost reduction is not easy due to performance or manufacturing restrictions. Under these circumstances, the present invention has been completed as a result of various studies aimed at shortening the steps and achieving cost reduction while maintaining the performance as a composite laminate.

[0005]

According to the present invention, a step of applying a thermosetting resin varnish from one surface of a long paper base material subjected to an undercoating treatment, and a step of superposing a glass fiber nonwoven fabric on the varnish application surface of the base material. And a step of obtaining a prepreg by heating and drying these laminates, and a step of superposing two sheets of the prepreg with the non-woven fabric inside to heat and press-mold the laminate. ,
The manufacturing process is simple, continuous molding is possible, and it is possible to obtain the same or better performance than the conventional composite laminated board in terms of performance. In the present invention, an example (outline) of steps up to the production of a prepreg is shown in FIG.

A thermosetting resin varnish (2) is applied to the upper surface of the long base material (1) unwound from the unwinding device by a coater (3) so as to have a predetermined film thickness. As the long base material, a paper base material is applied from the viewpoints of cost reduction and punchability. Kraft paper, linter paper and the like are used as the paper base material, but it is preferable to pretreat the paper base material with a phenol resin, a melamine resin or the like in order to increase the wet strength. Further, in order to improve the moisture absorption insulating property, an undercoated one is preferably used. As the undercoat resin, a phenol resin, a melamine resin or the like is used,
The amount of the attached resin is preferably 5 to 25% by weight.

The thermosetting resin in the thermosetting resin varnish used in the present invention is preferably an epoxy resin, but in addition to this, a polyimide resin, an unsaturated polyester resin, a phenol resin or the like can be used. Although such a thermosetting resin varnish can be used as it is, it is preferable to add an inorganic filler. When an inorganic filler is added, punching workability and dimensional stability are maintained and improved, and the coefficient of thermal expansion in the Z direction is reduced, so that it is possible to improve through hole reliability. Such inorganic fillers include aluminum hydroxide, calcium carbonate, clay, talc, silica and the like, and the compounding ratio with respect to the resin is preferably 10 to 200% by weight. Below 10% by weight,
Through-hole reliability improvement effect is small, 200% by weight
If it exceeds, it becomes difficult to mix the inorganic filler.

The solid content of the thermosetting resin varnish is usually 60 to 80% by weight when the inorganic filler is not blended, and 65 to 90% by weight when the inorganic filler is blended (the inorganic filler is also a solid content. Calculation). The coating amount of the thermosetting resin varnish varies depending on the basis weight of the glass non-woven fabric used in the following steps, or the coating amount of the resin varnish when coating the resin varnish on the lower surface of the long base material, Normally, the solid content of varnish is 600 ~ per 1 m ^{2 of} long substrate.
It is about 1400 g, and the coating thickness (before drying) is 0.2 to
It is about 1.0 mm.

As the coater 3, there are a comma roll coater, a knife coater, a die coater, a reverse coater, etc., but since the coating thickness is as thick as 0.2 to 1.0 mm, it is necessary to make the varnish viscosity high. . Therefore, a method capable of applying a high-viscosity varnish, for example, a comma roll coater or a knife coater is preferable.

After coating the thermosetting resin varnish on a long base material, a glass nonwoven fabric (4) is overlaid on the upper surface thereof, while the back surface is coated with the thermosetting resin varnish as described below. Work. This coating is usually a roll coater (5)
However, the present invention is not limited to this. As the glass nonwoven fabric, one having a basis weight of 20 to 150 g / m ² is usually used. The thermosetting resin varnish applied to the long base material from the back side is to compensate for the thermosetting resin varnish that was initially applied not being sufficiently impregnated into the long base material. The amount of resin used may be small, and a resin having a solid content of 10 to 30% by weight is used for uniform impregnation.

After that, a thermosetting resin-impregnated prepreg in which a glass nonwoven fabric is laminated on a long base material is obtained by heating and drying through a drying device (6). Since the total thickness of the base material is thick, the heating and drying conditions are slightly stronger than usual, and are 120 to 180 ° C. and about 1 to 5 minutes. Then, the prepreg is cut into a predetermined length by a cutter (7). Alternatively, it may be subjected to continuous molding without cutting.

The prepreg thus obtained is heated and pressure-molded by stacking two sheets with the glass nonwoven fabric side inside. In this molding, two prepregs, which are usually cut to a predetermined length, are stacked and heated and pressed by a multi-stage press.
It is also possible to continuously heat and press two long prepregs, which are not cut, with one of them upside down. When the resin is an epoxy resin, the former molding method is usually performed, and the molding condition is usually 150 ° C to 150 ° C as in the case of the conventional composite laminated plate, although it depends on the fluidity of the impregnated resin.
180 ° C, pressure 20-70 kg / c, time 60-12
0 minutes is appropriate. Further, in the case of unsaturated polyester resin, the latter continuous molding method capable of low pressure molding can be adopted.

After the initial thermosetting resin has been applied to the long base material, a drying step by heating may be inserted before the glass nonwoven fabrics are laminated. By evaporating the solvent in this drying step, it becomes easy to convert the resin into the B stage in the heat drying after the glass nonwoven fabrics are superposed.

A composite laminated plate can be obtained by the steps as described above. In the present invention, however, the glass non-woven fabric is superposed after the thermosetting resin varnish is applied to the long paper base material. Even if the resin varnish is applied from the back side, the application / impregnation process is simple, and the cost of expensive glass woven cloth and glass nonwoven cloth can be reduced, so that cost reduction can be achieved. .

[0015]

EXAMPLES Next, examples of the present invention will be specifically described together with comparative examples.

Example 1 A kraft paper, which is a long-sized base material, which is first treated with a water-soluble phenolic resin so as to have a resin adhesion amount of 25 to 30%, is unwound, and subsequently, an inorganic material having the following composition is used. Varnish A containing a filler was applied by a knife coater to a thickness of 0.9 mm (before drying). (Combined with varnish A) Epoxy resin 100 parts by weight (including curing agent dicyandiamide and curing accelerator) Inorganic filler (aluminum hydroxide) 80 parts by weight Ultrafine particle silica 20 parts by weight Solvent (methyl cellosolve) 50 parts by weight Next, upper surface side The glass non-woven fabric with a basis weight of 75 g / m ² (EP-4075 manufactured by Nippon Vilene) is overlaid,
Varnish B having the following composition was applied to the back surface of the kraft paper using a roll coater. (Combining varnish B) Epoxy resin (same as above) 30 parts by weight Solvent (methyl cellosolve) 70 parts by weight

Subsequently, the base material coated with the above varnishes A and B was heated and dried at 140 ° C. for 3 minutes by a drying device to obtain a prepreg composed of a paper base material and a glass nonwoven fabric. Next, two of these prepregs are laminated with the glass nonwoven fabric side facing inward, 18 μm thick copper foil is further laminated on both sides, and laminated for 90 minutes at a molding temperature of 165 ° C. and a pressure of 60 kg / cm ² to obtain a thickness of 1 A copper-clad laminate of 0.6 mm was obtained.

<Example 2> Untreated kraft paper, which is a long base material, was unwound, and a prepreg was obtained using the above-mentioned varnishes A and B in the same manner as in the following examples. Was laminated to obtain a copper-clad laminate having a thickness of 1.6 mm. << Comparative Example 1 >> The inorganic filler-containing varnish A obtained in Example 1 was used as a glass non-woven fabric (EP40 manufactured by Nippon Vilene).
75) and impregnated and dried to prepare an intermediate layer prepreg. Next, the varnish B obtained in Example 1 was impregnated into a glass woven fabric (WE-18K RB-84 manufactured by Nitto Boseki) so that the resin content was 30 to 40%, and dried to prepare a prepreg for a surface layer. did. Next, a predetermined number of intermediate layer prepregs are stacked, and the surface layer prepregs are stacked above and below it,
Further, a copper foil with a thickness of 18 μm was superposed on both sides of the copper foil and heat-pressed to produce a copper-clad laminate having a thickness of 1.6 mm. << Comparative Example 2 >> Untreated kraft paper is impregnated with a resole resin having a tung oil modification rate of 35% to prepare a prepreg, and 8 pieces of this prepreg and copper foil with adhesive on both surfaces thereof are combined as a set under heat and pressure. Then, a copper-clad laminate having a thickness of 1.6 mm was produced.

With respect to the copper-clad laminates obtained in the above Examples and Comparative Examples, punching workability, warpage, dimensional change rate,
The coefficient of thermal expansion in the Z-axis direction and the electrical insulation after moisture absorption were measured. Table 1 shows the results.

[0020]

[Table 1]

Regarding the manufacturing cost, the method of the embodiment has a simple process, does not use a high-cost glass woven cloth, and uses a small amount of the glass nonwoven fabric. The plate is 20 compared to that obtained in the comparative example.
The cost could be reduced by about 30%.

[0022]

The laminate obtained according to the present invention has good warp characteristics and dimensional stability, a small coefficient of thermal expansion in the Z direction, no decrease in electrical insulation after moisture absorption, and excellent punching workability. Moreover, cost reduction can be achieved. Since the manufacturing process is also simple, it is suitable as an industrial laminated plate manufacturing method.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the steps until a prepreg is manufactured in the manufacturing process of the present invention.

[Explanation of symbols]

 1 Long base material 2 Varnish 3 Coater 4 Glass nonwoven fabric 5 Roll coater 6 Drying device 7 Cutter 8 Prepreg

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B32B 31/20 7148-4F B32B 31/20

Claims (2)

[Claims] 1. A step of applying a thermosetting resin varnish from one side of a long paper base material, a step of overlaying a glass fiber nonwoven fabric on the varnish application surface of the fiber base material, and heating and drying the laminate. And a step of obtaining two prepregs with the non-woven fabric inside, and heat-pressing the two prepregs. 2. A method for producing a laminated board, wherein a paper base material subjected to an undercoating treatment is used as the long base material.