| 摘要 |
PURPOSE:To obtain favorable contact according to the difference of hardness of Sn and Pb when Sn bumps and Pb pads are to be made to come in contact mutually by pressure by a method wherein the bumps and the pads are formed of Sn and Pb, and are fusion welded heating at the temperature of fusion points or less of both the metals. CONSTITUTION:Layers consisting of Sn are provided at electrode parts, and are fused in a reducing atmosphere or in coexisting condition with flux to form spherical bumps 2 consisting of Sn. While pads 5 consisting of Pb layers having the prescribed thickness coated on the position to be made to come in contact with the bumps 2 are formed on conductor layers 4 on a substrate 3 side. Positioning of the pads and the bumps is performed, load is applied, heat or supersonic vibration is applied, the hard Sn bumps are made to encroach upon the soft Pb pads, and both are made to come in contact favorably. Then it is heated at the temperature of fusion point of Sn (232 deg.C)or less and at the temperature of eutectic point of Pb-Sn (188 deg.C) or more. As a result, the contact point of Sn and Pb is fused making a Pb-Sn eutectic crystal. |
