| 摘要 |
PURPOSE:To prevent the break of a junction to occur with the heat cycle of a device using a low melting point alloy for soldering by a method wherein the solder is rapidly solidified by cooling after reflow. CONSTITUTION:For a wiring substrate 2, an In-group three-element eutectic alloy made of Bi-Sn-In in used as the solder, and solder bumps are formed at the junction of the substrate 2 and at the junction of a chip 3, and then joined by flip chip bonding. In this case, after reflow of the solder by flip-chip face- down bonding the substrate to the chip on a working table on a cooling bath 1, cooling water 4 is introduced into the bath 1 and the solder is cooled at a cooling speed of 1 deg.C/sec or more. This manner enables the relaxation of thermal strains received in the solder junction when an electronic component receives heat cycle. |
