|Ask the Experts|
April 21, 2008
Eutectic reflow for Pb-free BGAs
Can I reflow Pb-free BGAs through an eutectic reflow process?
|Expert Panel Responses|
No, because the reflow temperatures in the eutectic process will not be hot enough to melt the lead free solder balls on the BGA.
Regional Sales Manager
OK International Inc.
Yes you can. The most important aspect of this reflow is the melting of the Pb-free solder balls of the BGA so that there will be adequate mixing of the molten solder from the solder ball and the solder paste. The reflow temperature and time above liquidus are critical, because of the SAC bumps on the BGA. A reflow temperature of around 220-225 degree C with an extended TAL (around 75 seconds) would be helpful in melting the balls, providing sufficient time for the lead from the solder paste to mix within the bulk, and the solder to wet the PCB pads. Depending on the finish on the PCB pad, the extended TAL may form thicker intermetallic. The user needs to be aware of this.
inspīre solutions LLC
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