BOARD-LEVEL RELIABILITY FOR LEAD-FREE QFP ASSEMBLYAuthor: Shan-Pu Yu
Date Published: 6/12/2001 Conference: Advanced Packaging Technology
All samples passed the electrical test after 2500 thermal shock cycles and also passed after random vibration test after twice tests. In this study, both Sn-Pb and lead-free Sn-Ag-Cu solder joints of QFP possesses good board-level reliability.
The failure of the Sn-Pb as-soldered joints occurs at the lead / solder interface results from most thermal stress locates due to CTE mismatch while cool down. The failure of the Sn-Ag-Cu solder joints some occurs at the lead / solder interface like Sn-Pb does, but a few samples fails at the Cu / PCB interface. Both Sn-Pb and Sn-Ag-Cu solder joints fails at the lead / solder interface after thermal shock test. However, more defects and coarsened grains would cause lower pull-forces of the Sn-Pb solder joints. Further investigations on the failure mechanism are still understudy.
Key words : lead-free, QFP, board-level reliability, solder joints.
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