Indium Corporation - Mailchimp

The Effect of Reflow Profiling on the Electrical Reliability of No-Clean Solder Paste Residues

At APEX 2014, I presented a paper about the effect that reflow profiling has on the SIR (Surface Insulation Resistance) performance (electrical reliability) of no-clean solder paste flux residues. In this study, I looked at two different SAC305 no-clean solder pastes; one with a J-STD-004B classification of ROL0 and the other with a classification of ROL1. Both pastes were submitted to reflow profiles with peak temperatures of 225C, 235C, 245C and 255C. Each peak temperature had two different "shaped" profiles; one with a very linear ramp rate and the other with a short high temperature soak.

225C Peak Temperature Linear Reflow Profile

So, overall, I looked at the effect of flux chemistry, peak temperature, and profile shape (linear and soak) on electrical reliability.

I was surprised to see that even with very low peak temperatures it was possible to obtain good SIR readings. Many times, implementing a short high temperature soak was as effective or more effective than increasing the peak temperature by 10C.

Please fell free to contact me with any questions or concerns.