JPH11335997A - Resin powder internal sheet - Google Patents

Abstract

[PROBLEMS] A resin powder capable of removing voids in a laminated board and impregnating a copper foil circuit having irregularities completely without impregnating the resin but internally adding the resin. Provide an internal sheet. A sheet internally containing a resin powder mainly comprising a base fiber and a composite resin powder whose surface of an inorganic filler is covered with an uncured thermosetting resin, wherein the base fiber, the composite resin powder and Having a weight ratio of 20:80 to 50:50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin powder-containing sheet used for a laminate for an electric insulating material such as a printed wiring board.

[0002]

2. Description of the Related Art Printed wiring boards used in computers, electric appliances and electric appliances are composed of conductors for transmitting electricity and insulators. The insulating layer in the multilayer material is generally manufactured by impregnating a glass cloth or a nonwoven fabric with a thermosetting resin varnish, and heating and semi-curing a prepreg. In recent years, with the improvement of wiring board manufacturing technology and the trend toward weight reduction, the demand for a thinner insulating layer of a multilayer printed wiring board has been increasing year by year. In addition, the distance between conductors has become narrower with the increase in wiring density. Therefore, high dimensional stability and high electrical insulation have been required for the thin insulating layer.

In order to cope with the thinning of the insulating layer, a technique of reducing the thickness of a glass cloth used for a prepreg has been adopted as an extension of the prior art. Currently, the thinnest material for electrical insulation glass cloth is the nominal thickness (MIL part number).
104) 25 μm. However, since the glass cloth having a nominal thickness of 25 μm is very thin, if the tension control is not performed sufficiently during the impregnation of the resin varnish, the glass cloth is likely to bend, cut, and the like, so that the cost is high.

[0004] In order to solve these problems, Japanese Patent Laid-Open No.
JP-A-109273 and JP-A-9-70921 disclose that an epoxy resin powder is internally added together with glass fibers in a paper making process instead of impregnating a non-woven fabric with a thermosetting resin varnish, and then heated and dried as it is to form an insulating layer. It is described that a thin prepreg sheet having a thickness of 100 μm or less is obtained.

[0005] The prepreg manufactured by such a method is as follows.
It is suitable for the production of thin prepregs, but on the other hand, a glass cloth vapour is used to dehydrate a large amount of water on the papermaking wire.
The problem is that the paper layer is much more porous than the prepreg, and the density of the prepreg sheet is very low. When a prepreg sheet having a porous structure is laminated and pressed, in order to completely remove voids and completely fill a space of a copper foil circuit having irregularities, the ratio of fiber to resin should be 40:60 to 10:90. , It was necessary to add resin powder internally. However, a prepreg sheet containing an excessive amount of resin internally has problems such as deterioration of the thermal dimensional stability of the laminate and adhesion of resin powder to a paper machine even during prepreg production.

[0006]

Accordingly, an object of the present invention is not to impregnate a resin, but to remove voids in a laminated board despite internal addition to completely fill a space of an uneven copper foil circuit. An object of the present invention is to provide a resin powder-containing sheet that can be embedded.

[0007]

Means for Solving the Problems A first invention of the present invention for solving the above-mentioned problems is to provide a base fiber, a composite resin powder in which the surface of an inorganic filler is covered with an uncured thermosetting resin. The present invention relates to a resin-powder-containing sheet having a base material and a composite resin powder in a weight ratio of 20:80 to 50:50. The second invention of the present invention is the first invention, wherein the weight ratio of the uncured thermosetting resin of the composite resin powder to the inorganic filler is from 30:70.
The present invention relates to a resin powder-containing sheet having a ratio of 70:30.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION
Basically, it is composed of a base fiber and a composite resin powder in which the surface of an inorganic filler is covered with an uncured thermosetting resin. By adopting such a configuration, voids in the laminate are removed even though the ratio of the thermosetting resin is reduced because the filler enters the voids in the base fiber, and the copper having irregularities is formed. It is possible to obtain a resin powder internal additive sheet that can completely fill the space of the foil circuit. The weight ratio between the base fiber and the composite resin powder is preferably in the range of 20:80 to 50:50.

The base fiber used in the present invention is not particularly limited as long as it has a certain level of electrical insulation and heat resistance, and various inorganic fibers and organic fibers can be used. Examples of the inorganic fibers include glass fibers, ceramic fibers, and rock fibers, and examples of the organic fibers include aramid fibers, polyester fibers, and wood pulp. However, the fibers are not limited to these fibers.

[0010] Examples of the inorganic filler used in the composite resin powder include fillers such as silica powder, aluminum oxide and calcium carbonate. The inorganic filler is desirably subjected to various coupling treatments in order to improve the affinity with the resin.

As the thermosetting resin for containing the inorganic filler, for example, epoxy resin, phenol resin,
There is no particular limitation as long as it does not impair electrical insulation and heat resistance, such as polyimide resin and bismaleimide resin. Since the thermosetting resin must be melted in the subsequent laminate manufacturing process to fill voids in the sheet, it is internally added to the sheet in an uncured state.

The weight ratio of the uncured thermosetting resin to the inorganic filler in the composite resin powder is preferably from 30:70 to 70:30. If the weight ratio of the uncured thermosetting resin is less than 30, the amount of resin required to fill the voids is insufficient, and if the weight ratio of the uncured thermosetting resin exceeds 80, the amount of the inorganic filler is reduced. Insufficient dimensional stability can be obtained due to shortage. The composite resin powder of the present invention can be exemplified by a method in which an uncured thermosetting resin is melt-blended in a filler and reground, or a method in which the filler is poured into a varnish and pulverized after removing a solvent, and the like. Not something.

The resin powder-containing sheet according to the present invention is desirably manufactured by a wet method in consideration of the uniformity of the sheet. The wet method is a method in which a slurry in which fibers are dispersed in water and a slurry in which a resin is dispersed in water are mixed in advance, and then the slurry is formed into a sheet. Machines used in the method include, for example, an inclined wire mesh paper machine, a circular net paper machine, and a fourdrinier paper machine.

Various binders and additives can be used in the nonwoven fabric of the present invention, if necessary. It is desirable to select a binder that can be cured at a temperature in the range of 100 ° C. to 180 ° C. so that sufficient strength is exhibited in the papermaking process. For example, self-crosslinking acrylic emulsion, phenol emulsion, epoxy resin, water-soluble silicone, alumina sol and the like can be exemplified. In addition, as an additive, a coupling agent, a flame retardant, and the like can be added as needed within a range that does not impair the properties of the laminate. The binder is added, for example, by spraying the wet-formed sheet or by impregnating the sheet into the binder.

The resin powder-containing sheet according to the present invention is heated and dried to form a prepreg sheet, and a laminated board can be produced by a usual method. For example, a laminated board can be obtained by stacking a predetermined number of prepreg sheets, further stacking copper foil on both sides, and applying heat and pressure. At that time, the uncured thermosetting resin in the composite resin powder melts and fills voids and voids in the prepreg sheet.

[0016]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the content of the present invention is not limited to Examples.

<Example 1> Epoxy resin (Epicoat E5048; Yuka Shell Epoxy Co., Ltd.) as a thermosetting resin
100 parts by weight, phenol novolak resin (TD-213)
1; 35 parts by weight of Dainippon Ink and Chemicals, 0.15 parts by weight of phenylimidazole as an accelerator were melt-blended at 100 ° C., and alumina powder was used as an inorganic filler (Sumitomo Chemical AL-33 average particle diameter 12 μm). Was kneaded and then pulverized to produce a composite resin powder having an average particle size of 100 μm. The weight ratio between the thermosetting resin and the alumina powder was 50:50.

Next, a glass fiber (CS10JAGP195; Nippon Electric Glass Fiber Co., Ltd.) was dissolved in an aqueous solution in which polyethylene oxide was dissolved at a concentration of 50 mg / l as a dispersant.
And a fiber diameter of 9 μm and a fiber length of 10 mm) were added to a concentration of 0.5% by weight and dispersed, and then a composite resin powder was added to form a uniform slurry. The weight ratio between the glass fiber and the composite resin powder was 40:60. The slurry was paper-made and dried to obtain a resin powder-inner sheet having a rice pyong of 75 g / m ² . This resin powder internal-added sheet 20 ply and 18 μm
m copper foil, 170 ° C, 90 minutes, 40kgf / cm
The laminate was heated and pressed under the conditions of ² to obtain a laminate having a thickness of 1.6 mm.

Comparative Example 1 A resin powder-containing sheet was prepared in the same manner as in Example 1 except that a resin powder containing no inorganic filler was used, and a laminate was prepared.

Example 2 An epoxy resin (Epicoat E5048; Yuka Shell Epoxy Co., Ltd.) was used as the thermosetting resin.
100 parts by weight, phenol novolak resin (TD-213)
1; 35 parts by weight of Dainippon Ink and Chemicals, 0.15 parts by weight of phenylimidazole as an accelerator were melt-blended at 100 ° C., and then silica powder (average particle size: 20 μm) was kneaded as an inorganic filler. Pulverization was performed to produce a composite resin powder having an average particle size of 100 μm. The weight ratio between the thermosetting resin and the silica powder was 70:30. Aramid fiber (Tecjin Technora fiber;
Fiber length 3 mm cut length) was used, and the weight ratio between the base fiber and the composite resin powder was 50:50. Other conditions were the same as in Example 1 to prepare a resin powder-containing sheet and a laminate.

Example 3 In Example 1, the weight ratio of the thermosetting resin to the alumina in the composite resin powder was 30: 7.
0, and the weight ratio of the base fiber to the composite resin powder was 30:70.
And Other conditions were the same as in Example 1 to prepare a resin powder-containing sheet and a laminate.

Comparative Example 2 A composite resin powder was prepared in the same manner as in Example 1 except that the weight ratio between the uncured thermosetting resin and the alumina powder was 25:75. A resin powder-containing sheet was prepared in the same manner as in Example 1 except that the weight ratio between the base fiber and the composite resin powder was changed to a ratio of 60:40. This resin powder internal sheet 20 ply and 18 μm
The copper foils were stacked and press-formed, but voids occurred and a laminate could not be formed.

Comparative Example 3 A composite resin powder was prepared in the same manner as in Example 1 except that the weight ratio between the uncured thermosetting resin and the alumina powder was 25:75. A resin powder-containing sheet was prepared in the same manner as in Example 1 except that the weight ratio between the base fiber and the composite resin powder was set to 10:90. The sheet containing the resin powder had a very low sheet strength and could not be formed.

The papermaking properties of the resin powder-containing sheets of Examples and Comparative Examples during papermaking were examined. In addition, the formability during the production of the laminate was examined, and the coefficient of thermal expansion and the insulation resistance of the laminate were measured. (1) Papermaking properties. The quality was visually observed. ○ Good. (2) Formability. The quality was visually observed. ○ Good. (3) The coefficient of thermal expansion was measured by a TMA method, and the coefficient of thermal expansion below Tg (glass transition point) was α1, and the coefficient of thermal expansion above Tg (glass transition point) was α2. Unit: (ppm / ° C) (4) Insulation resistance. After the laminate was pretreated with boiling water for 2 hours, the electrical insulation was measured according to JIS-C-6471.

[0025]

[Table 1]

[0026]

According to the present invention, the step of impregnating the varnish can be omitted by incorporating the composite resin powder in which the surface of the inorganic filler is covered with the uncured thermosetting resin into the resin powder-containing sheet. Can be easily manufactured. Further, it becomes possible to provide a resin powder internal-added sheet for a printed wiring board which is excellent in dimensional stability, which is a disadvantage of the conventional thermosetting resin powder-internally-added sheet.

Claims (2)

[Claims] Claims: 1. A resin powder-containing sheet mainly comprising a base fiber and a composite resin powder whose surface of an inorganic filler is covered with an uncured thermosetting resin, wherein the base fiber and the composite resin powder And a weight ratio of 20:80 to 50:50. 2. The resin powder internal sheet according to claim 1, wherein the weight ratio of the uncured thermosetting resin to the inorganic filler in the composite resin powder is 30:70 to 70:30.