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Ask the Experts

June 25, 2007 - Updated
July 3, 2007 - Originally Posted

Lead Free BGA Reflow

I want to evaluate lead-free BGA reflow capability. I have lead-free BGAs and HASL boards. Will this give me a close approximation of what my final process will be when I spec in ENIG or IMAG boards?

J.O.

Expert Panel Responses

No it may not, as you failed to mention whether or not your HASL boards are Sn/Pb or Sn100C solder leveled. Lead-free BGAs also have to be evaluated for what type of solder balls or columns are used on the device. Different types of metallurgy will react differently with different types and amounts of solder paste. You need to know the metals which are being soldered on both the component and board to make a final decision. The ENIG boards should solder well, but keep in mind the metal loading in the board and by this I'm driving the heat sinking effect of the inner layers, the dispersion pattern, the internal vias, etc. while developing the proper thermal profile for reflowing those particular types of components. IMAG may have shelf life issues and oxidation issues which may need to be addressed with the fluxes within the solder paste. Although it may seem simple, there are many subtle issues which need to be addressed and evaluated to make sure the correct process parameters are developed for the product. So will it give you a close approximation of the final process, I would move very carefully as I stated the different metallurgies behave differently and need to be checked out.

Leo Lambert
Vice President, Technical Director, EPTAC Corporation

At EPTAC Corporation, Mr. Lambert oversees content of course offerings, IPC Certification programs and provides customers with expert consultation in electronics manufacturing, including RoHS/WEEE and lead free issues. Leo is also the IPC General Chairman for the Assembly/Joining Process Committee.

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