JP2002299814A - Method of manufacturing multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer wiring board equipped with an inner circuit efficiently through a simple manner. SOLUTION: Conductive resin is directly applied/incorporated and formed into a circuit conductor on a base material of glass cloth or paper for the formation of an inner base material, and a multilayer printed wiring board is manufactured by the use of the above inner base material. Or, prepregs with voids are stacked and formed into one piece by thermocompression for the formation of a multilayer printed wiring board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art The integration density of electronic components such as semiconductor chips is extremely high. Therefore, the density of the electronic components has been increased by reducing the spacing between wiring and connecting holes of a printed wiring board on which the components are mounted. Have been Further, in the multilayer printed wiring board, a conductor circuit is formed on a plurality of substrates in advance, and these are bonded to each other, so that a higher density can be obtained. This multilayer printed wiring board is formed by multilayering a printed wiring board on which a conductor circuit has been formed in advance by a glass cloth prepreg. However, in the thinner and finer pitch demanded year by year, the cost of a multilayer board using a prepreg is high,
The problem is to reduce the overall thickness.

[0003] Therefore, in recent years, a technique for forming a multilayer using a resin instead of a prepreg has been developed. This is a method in which an insulating resin layer is formed on a printed wiring board that has been subjected to an inner layer treatment to form a multilayer, and a wiring pattern is formed thereon. In this method, a resin layer is formed directly and then an internal and external connection hole is opened, or a resin coating and a copper foil are continuously laminated at the same time and laminated, and then an internal and external connection hole is opened. And a method of directly laminating a copper foil with an insulating resin or a method of forming a resin layer which is cured by light, and forming a connection hole by a photographic process after exposure.

[0004]

However, recently, a resin-only layer having a higher density than a single layer has been proposed and manufactured in a plurality of layers. Therefore, the steps involved in manufacturing are complicated, and the cost is also increased. In addition, the time required for manufacturing is increased because of the multiple steps. Therefore, the circuit is not formed by etching the copper foil but is formed by a conductive resin. However, this technique can be applied only to the outer layer. Because, when used for the inner layer, at the time of multilayer press,
This is because the conductive resin moves and breaks due to the resin flow when molding with a thermosetting resin.

An object of the present invention is to provide a method for efficiently manufacturing a multilayer wiring board having an inner layer circuit by a simple method.

[0006]

The present invention is characterized by the following. (1) A method for manufacturing a multilayer printed wiring board using an inner layer base material in which a conductive resin is directly applied and impregnated in the shape of a circuit conductor onto a base material such as glass cloth or paper. (2) Multilayer in which a prepreg having voids and an inner layer substrate in which a conductive resin is directly applied and impregnated in the form of a circuit conductor on a substrate such as glass cloth or paper are laminated, and then heated and pressed to laminate and integrate. Manufacturing method of printed wiring board. (3) The method for producing a multilayer printed wiring board according to (2), wherein the prepreg having voids has voids of 20 to 80 vol% that can become open cells when heated.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a conductive circuit inside a circuit board having a plurality of layers is printed on a base material to be used in advance by using a conductive resin, and then a porosity of 20 to 80 vol.
Using a resin sheet having voids that can become open cells at the time of heating at 1%, the layers are multilayered, and a multilayer printed wiring board is manufactured at a time. At this time, the present invention provides a method for manufacturing a printed wiring board, characterized in that molding is performed by eliminating voids, that is, the resin is reduced and molded in the thickness direction, instead of molding by flowing a conventional resin.

Hereinafter, the present invention will be described in detail. As the conductive resin, Au, Ag, Cu, Ag / Pd, Ag / P
It is desirable that a powder of t, Ni, W and an alloy thereof be dispersed as an electric conductor in a matrix resin, and be solidified and cured. The conductive material is preferably 70 to 90 wt%. Examples of the base material include a base material formed by papering organic and inorganic fibers, such as kraft paper, glass-mixed paper, glass paper, and aramid paper. Examples of the thermosetting resin include a phenol resin, a urea resin, a furan resin, and an epoxy resin. Epoxy resins are particularly good in terms of moisture resistance, insulation, workability, handleability, and price.

As the type of epoxy resin, a bifunctional or higher functional epoxy resin is used. For example, bisphenol A epoxy resin, bisphenol F epoxy resin,
Bisphenol AD type epoxy resin, tree type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, diglycidyl etherified product of polyfunctional phenol, these hydrogenated products, etc. Types or combinations can also be used. When flame retardancy is required for the manufactured insulating resin, a halogenated epoxy resin is blended. Further, in order to satisfy the flame retardancy without adding these halogenated epoxies, generally, a flame retardant such as tetrabromobisphenol A, decabromophenyl ether, antimony oxide, tetraphenylphosphine, zinc oxide, etc. A compound referred to as an agent may be added as long as the properties are not significantly reduced. About 30 parts by weight or less is preferable for about 100 parts by weight of the epoxy resin.

As a curing accelerator, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt or the like is used. By using an imidazole compound having a potential, the storage stability of the resin film can be enhanced. As the imidazole compound used herein, imidazole, 2-methylimidazole, 4-ethyl-
2-methylimidazole, 2-phenylimidazole,
2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,
5-diphenylimidazole, 2-methylimidazoline, 2-ethyl-4-methylimidazoline, 2-undecylimidazoline, 2-phenyl-4-methylimidazoline, and the like. Examples include methylene diisocyanate, methylene bis isocyanate, and melamine acrylate. These curing agents may be used alone or in combination, and the amount is preferably 0.01 to 6 parts by weight based on 100 parts by weight of the epoxy resin. When the content is 0.01 or less, the effect is small, and when the content is 6 or more, the storage stability deteriorates.

As the solvent, acetone, butanone, toluene, xylene, 4-methyl-2-pentanone, ethyl acetate, ethylene glycol monoethyl ether, N, N
-Dimethylformamide, N, N-dimethylacetamideethanol and the like, and there are aqueous solutions by organic solvents, saponification, micro-dispersion and the like, and these may be used alone or in combination. In addition to the above essential components, other compounds can be mixed as necessary, as long as the effects of the present invention are not impaired. This thermosetting resin is impregnated into the substrate,
Heat-drying is performed to remove the solvent and perform thermosetting to obtain an adhesive sheet. The porosity of this adhesive sheet is 20 to 80 v
ol% is good, and preferably 30 to 65 vol% is preferable from the viewpoint of moldability and handling characteristics.

[0012]

Example 1 Using an electrically conductive paste MP-200CH (trade name, manufactured by Hitachi Chemical Co., Ltd.), the inner layer circuit was printed using a glass cloth GA-9020UN4ST (trade name, manufactured by Unitika Ltd.). Printed on. Thereafter, drying was performed at 80 ° C. for 60 minutes and thermal curing was performed at 160 ° C. for 40 minutes, thereby producing an inner layer circuit. A multi-layer press was performed using GEA-679P (trade name, manufactured by Hitachi Chemical Co., Ltd.) (porosity: 52%), which is a glass paper epoxy resin sheet having a thickness of 80 μm. Multilayering is performed by forming a 12 μm-thick copper foil GTS-12 (made by Furukawa Circuit Foil Co., Ltd., trade name) on the outer layer, the above inner circuit on the inner layer, and GEA-
679P (trade name, manufactured by Hitachi Chemical Co., Ltd.) and the pressing conditions were a high temperature holding temperature of 185 ° C. and a holding time of 9 hours.
It was produced at a holding pressure of 3.0 MPa for 0 minutes. Thereafter, a necessary portion was perforated, a conduction was performed, and an outer layer circuit was processed to obtain a multilayer printed wiring board.

Comparative Example 1 At the time of the multilayer press of Example 1, GEA-679P (trade name, manufactured by Hitachi Chemical Co., Ltd.) was replaced with GEA-679N which is a glass woven epoxy resin adhesive sheet (porosity: 5%).
(VUJJ) (trade name, manufactured by Hitachi Chemical Co., Ltd.). Other conditions were the same as in Example 1.

COMPARATIVE EXAMPLE 2 A similar inner layer circuit of Example 1 was produced by etching a laminated board with copper foil, and was a glass woven epoxy resin adhesive sheet (porosity: 5%) in a multilayer press. 67
9N (VUJJ) (trade name, manufactured by Hitachi Chemical Co., Ltd.)
And made it. Other conditions were the same as in Example 1.

The total time and the results of the continuity test for producing a multilayer printed wiring board were evaluated.

[0016]

[Table 1]

[0017]

In the first embodiment, compared to the first and second comparative examples, the required time is shorter and the conductivity is better.

Claims (3)

[Claims] 1. A method of manufacturing a multilayer printed wiring board using an inner layer base material in which a conductive resin is directly applied and impregnated in the shape of a circuit conductor onto a base material such as glass cloth or paper. 2. An inner layer base material in which a conductive resin is directly applied and impregnated in the form of a circuit conductor on a base material such as glass cloth or paper, and a prepreg having voids are laminated, and heated and pressurized to form a laminated integrated body. Manufacturing method of a multilayer printed wiring board. 3. The method for producing a multilayer printed wiring board according to claim 2, wherein the prepreg having voids has voids of 20 to 80% by volume which can become open cells when heated.