Tokyo Tungsten Co., Ltd.

Allied Material Corporation

Akira Ichida

Tadashi Arikawa

Mitsuo Osada

Norio Hirayama

Hidetoshi Maesato

Kiyoshi Asai

Yoshinari Amano

Kenji Sakimae

Hiroshi Yoshida

Yoshihiko Doi

Masahiko Mizukami

Tadashi Igarashi

Mitsuru Tsuchiya

A package to be mounted with semiconductor chips has a heat-radiating substrate having a thickness of smaller than 0.4 mm of a Cu&#x2014;Mo composite as prepared by impregnating from 30 to 40% by mass of copper (Cu) melt into a green compact of molybdenum. The heat-radiating substrate is produced by preparing an Mo green compact through isostatic molding, mounting Cu on the Mo green compact, heating it to thereby impregnate copper into the Mo green compact to give a Cu&#x2014;Mo composite, and rolling the Cu&#x2014;Mo composite into a sheet substrate. In the isostatic molding process, at least two or more platesandare disposed adjacent to the inner surface of a side wall as divided into at least two portions, Mo powder is filled into the space as formed by those platesandwith covering the Mo powder compact with a flexible cover, such as a rubber mediumor the like, to prepare a composite, then the resulting composite is put into a pressure tank, an external isostatic pressure is applied thereto against the flexible cover, and the plates are slid via the cover along the side wall thereby compressing the composite between the thus-slid plates into an Mo green compact.

Semiconductor package and method for producing heat-radiating substrate for it

A package to be mounted with semiconductor chips has a heat-radiating substrate having a thickness of smaller than 0.4 mm of a Cu&mdash;Mo composite as prepared by impregnating from 30 to 40% by mass of copper (Cu) melt into a green compact of molybdenum. The heat-radiating substrate is produced by preparing an Mo green compact through isostatic molding, mounting Cu on the Mo green compact, heating it to thereby impregnate copper into the Mo green compact to give a Cu&mdash;Mo composite, and rolling the Cu&mdash;Mo composite into a sheet substrate. In the isostatic molding process, at least two or more plates. and are disposed adjacent to the inner surface of a side wall as divided into at least two portions, Mo powder is filled into the space as formed by those plates and with covering the Mo powder compact with a flexible cover, such as a rubber medium or the like, to prepare a composite, then the resulting composite is put into a pressure tank, an external isostatic pressure is applied thereto against the flexible cover, and the plates are slid via the cover along the side wall thereby compressing the composite between the thus-slid plates into an Mo green compact.

In a package of a semiconductor device mounted a semiconductor element and micro balls as electric contact points, the micro balls are composed of composite micro balls each of which has a core ball and an electrically conductive film around the core ball. The core balls have a sufficient rolling property with the diameter ranged from 30 to 100 &mgr;m. The diameter accuracy thereof is excellent. The electrically conductive film is formed by a solder plated layer which has a thickness of at least 10 &mgr;m uniformly formed on the outer surfaces. The composite micro balls are mounted onto a substrate. The dimensional accuracy of the Z axis of the package can be precisely controlled. Accordingly, the composite micro balls with the solder plated film has a thickness of at least 20 &mgr;m on the outer circumference of each core ball. The production method thereof, and the semiconductor package mounted a semiconductor element using the composite micro balls can be provided.

Semiconductor package using micro balls and production method thereof

A heat sink substrate comprises a Cu&mdash;Mo composite substrate composed of a molybdenum (Mo) green compact with which Copper (Cu) of 20-60 wt % is impregnated. It is preferable that the heat sink substrate is a rolled plate obtained by repeatedly warm rolling or cold rolling the Cu&mdash;Mo composite substrate and that the rolled plate does not include any fine void and unevenly impregnated copper, that is, copper and molybdenum are uniformly distributed therein.

Heat sink substrate consisting essentially of copper and molybdenum and method of manufacturing the same

In a plastic-packaged semiconductor device molded by a synthetic resin, a heat sink is formed by a sheet which has a thermal expansion coefficient between 9.0.times.10.sup.-6 /K and 23.times.10.sup.-6 /K and a thermal conductivity greater than 200 W/m.multidot.K, which are selected in relation to those of the synthetic resin. The sheet is manufactured by mixing a first metal of a high melting point with a second metal of a low melting point lower than the first metal and by pressing and sintering the mixture. The first and the second metal may be molybdenum and copper, respectively. Alternatively, the sheet may be a composite sheet composed of a molybdenum mesh interposed between a pair of aluminum layers or a stacked sheet composed of a sintered layer of a mixture of molybdenum and copper and a coated layer of either molybdenum or copper.

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Toyama, Japan

Akira Ichida