| 摘要 |
PURPOSE:To obtain high reliability by preventing the break of solders connecting a substrate and an element due to thermal stress by a method wherein the gap between the substrate and the element is filled with an insulator having a coefficient of thermal expansion close to that of the solder. CONSTITUTION:The mixing ratio of the mixture 4 of alumina fine grains and a resin 5 is so set as to become close to the coefficient of thermal expansion of the solder 3. The gap between the substrate 1 and a flip chip 2 after they are soldered is filled with this mixture. The coefficient of thermal expansion of the mixture produced in such a manner can be varied according to the volume mixing ratio at the time of mixing the resin and the alumina fine grains: the coefficient can be made much closer to that of the solder. Therefore, the difference in the coefficient of thermal expansion between the solder and the mixture decreases, and generation of thermal stress diminishes, thus enabling the thermal fatigue of the solder to be prevented. At the same time, the mixing of the alumina fine grains with the resin increases the thermal conductivity and improves the heat dissipation of the chip. |
