Tatsuta Electric Wire & Cable Co., Ltd.

Norihiro Yamaguchi

Hiroaki Umeda

Ken Yukawa

Hajime Nakazono

A conductive paste having a viscosity suitable for filling a hole of a board, long pot life, and excellent conductivity and long-term reliability of a cured product, and a multilayer board using the same are provided. A conductive paste comprising with respect to (A) 100 parts by mass of dimer acid-modified epoxy resin, (B) from 200 to 1900 parts by mass of high melting metal powder containing silver-coated copper alloy powder and having a melting point of 800&#xb0; C. or higher, (C) from 400 to 2200 parts by mass of silver-coated copper alloy powder having a melting point of 800&#xb0; C. or higher, (D) from 1.0 to 20.0 parts by mass of curing agent containing a hydroxy group-containing aromatic compound, and (E) from 5.0 to 100.0 parts by mass of a flux containing polycarboxylic acid, is used as the present invention.

Conductive paste and multilayer board using the same

In a method of manufacturing a multilayer board, including: a drilling step for forming a via hole through a pre-preg by laser beam machining, a step of filling the via hole with conductive paste containing a resin component and metal powder, and a step of arranging copper layers or copper layer portions of patterned boards on and under the filled conductive paste and pressing the same, a multilayer printed wiring board superior in conductivity and long-term stability is obtained by using alloying paste as the conductive paste in which at least part of the metal powder is melted and the metal powders adjacent to each other are alloyed, using a pre-preg having a ratio A/B of at least 10 before subjected to preheating, where A is a storage modulus at an inflection point where the storage modulus changes from increasing to decreasing and B is a storage modulus at an inflection point where the storage modulus changes from decreasing to increasing in a temperature profile rising from 60&#xb0; C. to 200&#xb0; C., and preheating the pre-preg before the drilling step to reduce the ratio A/B to below 10.

Multilayer wiring board

A method of manufacturing a multilayer board, including: forming a hole through a pre-preg by laser, filling the hole with conductive paste containing a resin component and metal powder, and arranging copper layer portions of patterned boards on and under the filled conductive paste and pressing the same, wherein in the conductive paste at least surface layers of the different metal powders are melted and alloyed, the pre-preg has a ratio A/B of at least 10 before being subjected to preheating, where A is a storage modulus at an inflection point where the storage modulus changes from increasing to decreasing and B is a storage modulus at an inflection point where the storage modulus changes from decreasing to increasing in a temperature rising from 60 to 200 degree C., and preheating the pre-preg before the drilling step to reduce the ratio A/B to below 10.

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Higashiosaka, Japan

Norihiro Yamaguchi