| 摘要 |
PROBLEM TO BE SOLVED: To obtain a bump electrode with a high melting temperature and less thermal fatigue by forming the solder layer of the bump electrode with a specific range of alloy material of Pb-Sn-Sb-Ag. SOLUTION: By dipping solder containing an alloy constituent with a solid- phase wire temperature of 220 deg.C which consists of approximately 79wt.% lead, 14wt.% tin, 5wt.% Sb, and 2wt.% silver and flux is dipped, is applied, or selectively adhered, for example, by plating onto the upper layer of a middle metal layer 8 made of copper plating, thus forming a semi-spherical solder layer 9. A solder paste 12 with flux is selectively formed on a pad 11 where the length of one side of a square is equal to the diameter of the semi-spherical solder layer 9 on such an insulation substrate 10 as alumina. Then, a bump electrode 6 is tentatively sealed onto the pad 11 by utilizing the adhesive force of the solder paste 12 and is heated at approximately 305 deg.C under nitrogen atmosphere and then the solder layer 9 is subjected to reflow. The composition of the solder layer 9 should be Pb: 70-85wt.%, Sn: 10-20wt.%, Sb: 3-8wt.%, Ag: 1-5wt.%. |
