Dowa Mining Co., Ltd.

Masaya Takahara

Masami Kimura

Junji Nakamura

Masami Sakuraba

A metal-ceramic composite substitute is produced by joining a metal plate to a ceramic substrate by using a brazing material in a paste form prepared by adding 10-14 parts by weight of a vehicle to 100 parts by weight of a powder of which the solid centent comprises 90.0&tilde;99.5% of an Ag powder, 0&tilde;9.5% of a Cu powder and 0.5&tilde;4.0% of an active metal powder, and 0.0&tilde;0.9% of a titanium oxide powder if necessary.

Brazing material for use in joining a metal plate to a ceramic substrate

Process for producing a metal-ceramic composite substrate

In the present invention, a metal-ceramic composite substitute is produced by joining a metal plate to a ceramic substrate by using a brazing material in a paste form prepared by adding 10-14 parts by weight of a vehicle to 100 parts by weight of a powder of which the solid centent comprises 90.0&tilde;99.5% of an Ag powder, 0&tilde;9.5% of a Cu powder and 0.5&tilde;4.0% of an active metal powder, and 0.0&tilde;0.9% of a titanium oxide powder if necessary.

Metal-ceramic composite substrates, producing methods thereof and brazing materials for use in such method

A metal-ceramic composite circuit substrate having a ceramic substrate and a metal plate joined to at least one main surface of the ceramic substrate, the rate of voids formed on at least a joint surface at a semiconductor mounting portion of the metal plate per unit surface area being not more than 1.49%. The diameter of void formed on at least the joint surface at a semiconductor mounting portion of the metal plate is not larger than 0.7 mm. The surface undulation of the ceramic substrate is not more than 15 .mu.m/20 mm measured by a surface roughness tester in case that the ceramic substrate is joined directly to the metal plate. The metal plate is joined to the ceramic substrate through a brazing material containing at least one active metal selected from a group consisting of Ti, Zr, Hf and Nb. The ceramic substrate is at least one kind of ceramic substrate selected from a group consisting of Al.sub.2 O.sub.3, AlN, BeO, SiC, Si.sub.3 N.sub.4 and ZrO.sub.2.

Metal-ceramic composite substrate

A paste of active metallic brazing material is applied to the entire surface of each side of aluminum nitride or alumina ceramic substrate 1; circuit forming copper plate 3 having a thickness of 0.3 mm is placed in contact with one surface of the substrate and a heat dissipating copper plate 4 having a thickness of 0.25 mm placed in contact with the other surface; the individual members are compressed together and heated at 850.degree. C. in a vacuum furnace to form a joint; an etching resist is applied to the circuit forming copper plate and etching is performed with an iron chloride solution to form a circuit pattern and the unwanted brazing material is removed from the marginal portions; a second resist layer is applied and etched with an iron chloride solution to form a second marginal step; a third resist layer is similarly applied and etched to form a third marginal step; the completed circuit board having three marginal steps of which the lowest one is solely or partly made of the brazing material can withstand 1,500 heat cycles, which is the result that has ben unattainable by the prior art. Having such high heat cycle characteristics, the circuit board is suitable for use as semiconductor substrate in automobiles, electric trains and other applications that require high output power.

Semiconductor substrates of high reliability ceramic metal composites

A conductor pattern is formed on at least one surface of an AlN- or Si.sub.3 N.sub.4 -based ceramic substrate which is such that the ratio between the principal metal component binding with N to form the ceramic mass and the B in the BN remaining on the surface layer is no more than 50.times.10.sup.-6 as either B/Al or B/Si, wherein B/Al represents the ratio of I.sub.B to I.sub.Al where I.sub.B is the X-ray diffraction intensity of boron present on the surface layer and I.sub.Al is the X-ray diffraction intensity of aluminum, and B/Si represents the ratio of I.sub.B to I.sub.Si where I.sub.B is as defined above and I.sub.Si is the X-ray diffraction intensity of silicon. The thus produced circuit board has both a peel strength of at least 30 kg/mm.sup.2 and a capability of withstanding at least 30 heat cycles and, hence, satisfies the performance requirements of the recent models of power module ceramic circuit boards.

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Tokyo, Japan

Masaya Takahara