发明授权
US5936846A Optimized solder joints and lifter pads for improving the solder joint
life of surface mount chips
失效
优化的焊点和升降垫,以提高表面贴装芯片的焊接寿命
- 专利标题: Optimized solder joints and lifter pads for improving the solder joint life of surface mount chips
- 专利标题(中): 优化的焊点和升降垫,以提高表面贴装芯片的焊接寿命
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申请号: US786389申请日: 1997-01-16
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公开(公告)号: US5936846A公开(公告)日: 1999-08-10
- 发明人: Vivek Amir Jairazbhoy , Richard Keith McMillan, II , Yi-Hsin Pao
- 申请人: Vivek Amir Jairazbhoy , Richard Keith McMillan, II , Yi-Hsin Pao
- 申请人地址: MI Dearborn
- 专利权人: Ford Global Technologies
- 当前专利权人: Ford Global Technologies
- 当前专利权人地址: MI Dearborn
- 主分类号: H05K1/18
- IPC分类号: H05K1/18 ; H05K3/34 ; H05K1/14 ; H05K1/16
摘要:
There is disclosed herein a surface mount printed circuit board having a substrate, at least one surface mount device, at least two mounting pads per device, solder joints connecting the terminations of the device to their respective mounting pads, at least one rectangular lifter pad on the substrate amid the mounting pads, and a solder mass on each lifter pad in contact with the bottom surface of the device. The inner and outer extensions of the mounting pads, the size, number, and shape of the lifter pads, and the amounts of solder deposited on the mounting and lifter pads are designed such that the solder joint has preferably convex outer fillets, the device is maintained at a predetermined height above the mounting pads, the inner fillet angle is maintained above a predetermined minimum angle to increase solder joint crack initiation time, and the overall solder joint crack propagation length is increased. An alternate embodiment also includes plugged vias under the lifter pads and/or mounting pads, with gas pockets trapped between the solder masses/solder joints and the plugged vias. This trapped gas pocket provides additional buoyant force upon the SMD during reflow.
公开/授权文献
- US4650815A Foamed articles of fluorocarbon resins 公开/授权日:1987-03-17
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