Denso Corporation

Harima Chemicals, Incorporated

Nippondenso Co., Ltd.

Masanori Takemoto

Masami Aihara

Tatsushi Onishi

Koji Kondo

Kenji Kondo

Masayuki Aoyama

Naoki Ito

Hidehiro Mikura

Tetuhiro Nakano

An electronic component unit includes an interposer with a plurality of holes and a circuit wiring layer disposed on one surface of the interposer. The electronic component is electrically connected to the circuit wiring layer. A plurality of solder bumps are electrically connected to one surface of the circuit wiring layer through the holes formed in the interposer. The circuit wiring layer is electrically connected to an outside circuit through the solder bumps. A junction interface between the circuit wiring layer and each of the solder bumps is made of ductile metal.

Mounting structure of electronic component on substrate board

A BGA package is mounted on a multi-layer printed wiring board having a plurality of electrodes arranged in a matrix form through a plurality of solder bumps. In the most externally-located electrodes, a lead wire is formed to extend from a portion of the most-externally-located electrode located inside of a polygon formed by connecting each of the centers of adjacent most-externally-located electrodes. Therefore, the solder bumps are prevented from coming off the most-externally-located electrodes because a portion of the most-externally-located electrode to which stress caused by an external shock is intensively applied is located in an outside of the polygon. Thus, a contact failure between the BGA package and the multi-layer printed wiring board is prevented.

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.

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Anjo, Japan

Masanori Takemoto