发明公开
- 专利标题: Reflowed solder ball with low melting point metal cap
- 专利标题(中): 具有低熔点金属帽焊球
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申请号: EP96480060.1申请日: 1996-05-07
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公开(公告)号: EP0747954A2公开(公告)日: 1996-12-11
- 发明人: Dalal, Hormazdyar Minacher , Fallon, Kenneth Michael , Bitaillou, Alexis , Gaudenzi, Gene Joseph , Herman, Kenneth Robert , Robert, Georges , Pierre, Frédéric
- 申请人: International Business Machines Corporation
- 申请人地址: Old Orchard Road Armonk, N.Y. 10504 US
- 专利权人: International Business Machines Corporation
- 当前专利权人: International Business Machines Corporation
- 当前专利权人地址: Old Orchard Road Armonk, N.Y. 10504 US
- 代理机构: Lattard, Nicole
- 优先权: US476474 19950607
- 主分类号: H01L23/485
- IPC分类号: H01L23/485
摘要:
A method and structure for a solder interconnection, using solder balls for making a low temperature chip attachment directly to any of the higher levels of packaging substrate is disclosed. After a solder ball has been formed using standard methods it is reflowed to give the solder ball a smooth surface. A layer of low melting point metal, such as, bismuth, indium or tin, preferably, pure tin, is deposited on the top of the solder balls. This structure results in localizing of the eutectic alloy, formed upon subsequent low temperature joining cycle, to the top of the high melting solder ball even after multiple low temperature reflow cycles. This method does not need tinning of the substrate to which the chip is to be joined, which makes this method economical. It has also been noticed that whenever temperature is raised slightly above the eutectic temperature, the structure always forms a liquid fillet around the joint with copper wires. This liquid fillet formation results in substantial thermal fatigue life improvement for reduced stress at interface; and secondly, provides an easy means to remove chip for the purpose of chip burn-in, replacement or field repairs.
公开/授权文献
- EP0747954A3 Reflowed solder ball with low melting point metal cap 公开/授权日:1997-05-07
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