Harima Chemicals, Incorporated

Nippondenso Co., Ltd.

Denso Corporation

Waseda University

Masami Aihara

Masanori Takemoto

Tatsushi Onishi

Jun Mizuno

Naoki Ito

Hiroyuki Kuwae

Kosuke Yamada

Takayuki Ogawa

A bonding method is capable of realizing high bonding strength and connection reliability even at a connection part in a high temperature area by means of simple operation low temperature bonding. The method includes a first step wherein, on at least one of the bonded surfaces of two materials to be bonded having a smooth surface, a thin film of noble metal with a volume diffusion coefficient greater than that of the base metal of the material to be bonded is formed using an atomic layer deposition method at a vacuum of 1.0 Pa or higher, a second step wherein a laminate is formed by overlapping the two materials to be bonded so that the bonded surfaces of the two materials are connected through the thin film, and a third step wherein the two materials to be bonded are bonded by holding the laminate at a predetermined temperature.

Bonding method and structure

Disclosed is a solder bonding structure which is capable of retaining sufficient solder bonding strength and ensuring high bonding reliability even in severe environments having an extremely large temperature difference. In the solder bonding structure, an electronic componentis mounted on a main surfaceof a substrate having an electrode sectionand an insulating film, and the electrode sectionand the electronic componentare electrically bonded to each other through a solder section, and a flux residueexuded from the solder sectionis present between the electronic componentand the insulating film. The flux contains an acrylic resin, an activating agent, and a thixotropic agent having a hydroxyl group. The glass transition point of the acrylic resin is not higher than &#x2212;40&#xb0; C., or not lower than the softening temperature of the flux residue. The flux residue has a maximum value of 300&#xd7;10/K or less of linear thermal expansion coefficient within a temperature range from &#x2212;40&#xb0; C. to the softening temperature of the flux residue.

Solder bonding structure and soldering flux

A non-washing soldering flux which is capable of minimizing corrosion and insulation defects due to precipitation of metal salts and cracking of the base resin is disclosed. The flux includes an activator including a dibasic acid with a molecular weight of 250 or less, and a monobasic acid with a molecular weight of from 150 to 300 and/or a dibasic acid with a molecular weight of from 300 to 600. The dibasic acid of molecular weight 250 or less in the flux exhibits sufficient activity, thus ensuring satisfactory solderability. The monobasic acid of molecular weight from 150 to 300 and the dibasic acid of molecular weight from 300 to 600 which are combined therewith promote the activity while also uniformly dispersing the metal salt of the low molecular weight dibasic acid in the flux residue, allowing it to be enveloped by the hydrophobic base resin. For greater cracking resistance, the flux includes at least an acrylic resin of molecular weight 10,000 or less and an activator.

Soldering flux

A soldering flux composition comprising, as a flux base resin, a modified amine compound obtained by reacting (i) at least one member selected from the group consisting of vinyl group-containing compounds, carboxyl group-containing compounds and epoxy group-containing compounds (ii) with an amine compound having an active hydrogen.

Soldering flux composition

Growing community of inventors

Kakogawa, Japan

Masami Aihara