| Hello Everybody: | | I am in urgent need of some information regarding the reflow profile for a flip chip wafer. Would the reflow conditions along with the flux used affect the appearence of the solder joints. | | We are witnessing dull solder joints after wafer reflow, which causes some placement issues. I would really appreciate if anyone of you would advise me about it. | | Regards | Susan | Susan,
No answers for you yet, just questions. Why are you bumping the wafer and not your supplier? Are you bumping using a stencil? What is the base metal of the wafer? What solder composition are you bumping with. If wafer metal is gold. The rate at which the gold dissolves into the solder will increase as the reflow temp increases. If the wafer pad is gold, and the gold constitutes a large percentage of the solder joint, you will have week, very grainy solder joints. What problems are you having at placement due to dull solder joints. I suspect a vision recognition problem.
Very interested in what you find out and what your process is. Have investigated this in the past but always run into the gold imbrittlement problem due to wafer pads being way too thick with gold.
Thanks,
Chris G.
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