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August 20, 2012

Mixing SAC305 and SACX0307 Solder Alloys

What is the effect of mixing solder alloys? For example mixing SAC305 and SACX0307? We have a huge inventory of SAC305 and we don't know what to do with it.


Experts Comments

The effects are unknown because you would really never know the exact alloy you are working with at any given time.  I would recommend  disposition of your SAC305 either by selling, disposing (return to OEM), or using in it's pure form.
Mark Waterman
Engineer / Trainer
Electronic Controls Design, Inc. (ECD)
Mark Waterman is a trainer and field engineer with 17 years experience in service and applications specialties. Intimate knowledge of soldering processes and measurement systems. Six sigma and statistical process control generalist.
These alloys really should not be mixed together.  The benefits of the SAC305 system are a little different than those from the SACX0307 system, and mixing the alloys together could produce unknown side effects. If you are committed to the low-Silver alloy (SACX0307), there are certain benefits that you should be expecting that would be diluted if you mixed in the SAC305 alloy. Additionally, the melting temperature of the material in the solder pot could be impacted by mixing the two alloys together, which could lead to poor alloy flow and poor hole-fill as a result.

The SAC305 bar solder in your inventory has value, without any doubt, and there are companies that will pay you for this material. I would recommend contacting your bar solder supplier and/or a metal reclaimer to see who will make you the best offer for your SAC305 alloy material.
Brian Smith
General Manager - Electronic Assembly Americas
DEK International
Mr. Smith has been supporting customers in the electronics assembly industry since 1994. His expertise is focused on solder paste printing and reducing soldering defects. He holds a BS in Chemical Engineering and an MBA in Marketing. He has authored several papers in trade magazines and at industry conferences. He is an SMTA Certified Process Engineer.
I would not recommend mixing the alloys. You maybe able to talk to your solder supplier and exchange the alloy with them.
John Norton
Eastern Manager
Vitronics Soltec
John Norton started his soldering career in 1983 for Hollis Engineering. He has also worked with Electrovert as a technical training manager and Vitronics Soltec for the last ten years. He has held various technical development and sales positions.
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