If you are here, you probably already know that Durafuse™ LT is a low-temperature solder with some special drop shock properties (they're fantastic, and yes, I may be biased - but it is also true). But I don't think I've really talked about how to get those properties in detail.
If you haven't had the chance to read my blog post about the reflow profile of Durafuse LT, it's probably a good place to start because you can see that sometimes the reflow profile for Durafuse LT looks flat on top. That flat topped profile is a feature - not a bug. In general, getting the reflow profile right for an SMT process is incredibly important. Don't worry; if we ever forget, my coworkers have a lot of blog posts detailing their experience to help remind us of the details.
With Durafuse LT, the reflow profile is not only important, but is directly tied to the drop shock performance of the alloy. Basically, when reflowed at 200℃, Durafuse LT gives you the same drop shock reliability as SAC305... but only if you hold it at peak temperature long enough. By long enough, I mean definitely more than 2 minutes; when someone asks, I recommend having 140s in the oven when the board is actually at 200℃.
To be clear, if we increase the reflow profile temperature just a bit (not too much! Just, say... 5℃) we don't need to stay at peak temperature nearly as long. That's where the chart below comes from. You have options - and if you ever need a hand navigating them, shoot me (or any of us!) an email. New technology is cool. Material science is cool. And it is always fun hearing about the new ways people are using materials science.