3/12/2024 0 Comments Leaded solder reflow profile![]() In Pb-free soldering, melt temperatures are typically higher, depending on the alloy used, and solderability is generally less robust than that of traditional Pb-based soldering. (Since then, I've learned more, such as the extended soak stage.In Lead-free (Pb-free) reflow soldering for SMT PCBAs, soldering defects associated with thermal profiling can be mitigated by a thorough understanding of the variables affecting the process, as well as the metallurgical dynamics associated therewith. It's not a 1-for-1 replacement.įYI, I made a video on bismuth-based low temp solder. But, you should consider if it is a good match for your application. When I have to rework something, it is much (much) quicker than traditional solder compounds. So you’ll need extra heat to get rid of it all.Īll-in-all, I like using the stuff. When reworking, any flux you add probably has a higher activation point than the the Bi-compound.The extended time here prevents solder balls from forming. On my reflow profile, I target 150C for about 150 seconds. It would be best if you gave time at 125C-140C for the flux to activate and the solder balls to start melting. The "blast it with heat" method people use with SnPb or SAC just does not work well with Bismuth-based. If reflowing, give a LOT of time during the soak stage.But, say, if you have a very sensitive control loop, it might be something to consider. Again, there are very few circuits where this matters. So, for example, instead of 10 milliohms of resistance, you might get 100 milliohms. But the Bismuth-based solder does have about one order of magnitude more resistance than either SnPb or SAC. ![]() In the vast majority of applications, this will not matter. Also, if you have surface mount connectors, make sure they have some form of mechanical stress relief. But be careful with components that might get as hot as 125C under regular operation. For everyday applications, this isn't a big deal.
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