Hitachi, Ltd.

Mitsunori Tamura

Shinichi Kazui

Yasuhiro Iwata

Mitsugu Shirai

Hiroshi Fukuda

Kaoru Katayama

Toshihiko Ohta

Osamu Yamada

Hideaki Sasaki

Ryohei Satoh

Tetsuya Hayashida

Kenichi Kasai

Mitugu Shirai

Masahito Ijuin

Makoto Matsuoka

Toru Nishikawa

Hideyuki Fukasawa

Tositada Netsu

Hideki Watanabe

Hiroyuki Hidaka

Masahide Hara

Hiroko Takehara

The process for manufacturing an electronic circuit includes disposing an electronic device on a circuit substrate and hot melting a solder formed on the electronic device or the circuit substrate to bond the electronic device and the circuit substrate. The process includes the steps of feeding a liquid onto lands on the circuit substrate, aligning and mounting the electronic device on the lands, placing the circuit substrate in a treating vessel and heating the circuit substrate. The heating step includes controlling a pressure of an atmosphere in the treating vessel, hot-melting the solder to prevent at least a portion of the liquid from evaporating until the electronic device and the circuit substrate are bonded and to permit the liquid to evaporate after the electronic device and the circuit substrate are bonded.

Process for manufacturing electronic circuits

A process for manufacturing electronic circuits, according to which soldering can be carried out without using flux by applying a metal surface treatment procedure which allows oxide film, organic matters, carbon or the like on the surface of metal to be easily removed without using a complex process nor unfavorably affecting electronic devices or circuit substrates. A process of connecting an electronic device and a circuit substrate by means of solder comprises the steps of irradiating the solder with a laser beam to clean the solder, aligning and mounting the electronic device on the circuit substrate, and hot-melting said solder in a low-oxygen content atmosphere to bond the electronic device and the circuit substrate.

A method of soldering used in fabricating an electronic circuit device employs an organic material supplied to at least one of the connecting members to be bonded. The connecting members are positioned in an oxidizing atmosphere, and heated in a nonoxidizing atmosphere to remove oxide and/or contamination layers present on the surface of presoldered portions or metallized bonding portions. By this method, fluxless soldering is performed, positional shifts are reduced, and high reliability of the soldering connections with reduction in residues after reflow are obtained.

Method of fabricating an electronic circuit device

There is disclosed a multichip module having a sealing-cooling structure which achieves a high packaging density, high sealing-connection reliability, a low manufacturing cost and a high cooling ability. A frame 15, conforming in thermal expansion coefficient to a substrate 11, is soldered at one surface thereof to that surface of the substrate 11 on which semiconductor devices 12 are mounted. The frame 15 is fastened or fixedly secured at the other surface thereof to a lid member 17 by bolts 10 or means without any heat treatment of the whole of the module.

Multichip module with heat sink and attachment means

A flexible film-like member having conductive metals filled in tapered holes extending through the thickness is positioned such that the holes of the member face to respective pad patterns on a circuit board on which bumps are to be formed, the conductive metals are then heated and fused so that they are joined and transferred to the pad patterns on the circuit board, and the film-like member is then removed by heating or cleaning liquid.

Method for forming conductive bumps

Growing community of inventors

Hadano, Japan

Mitsunori Tamura