| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve thermal fatigue life and to provide a simple means for removing chips for burn-in, replacement and field repair of the chips by depositing a layer of low melting point metal on an upper part of solder ball. SOLUTION: The solder ball 18, for example, is composed of alloy of Pb-Sn and the high melting point solder ball is formed on a metallurgical part 16 for limiting ball. The low melting point metal 23 such as Sn, is deposited on the solder ball 18. The low melting point metal 23 is selected from the group consisting of alloys of bismuth, indium or the like. The substrate 10 is selected from the group consisting of organic substrate, multi-layer organic substrate, ceramic substrate, multi-layer ceramic substrate or IC chip.</p> |
