For those of us who recommend solder alloys, Au/Sn holds a place in our hearts. In many cases it is the #1 solder for an application (if you don’t factor cost into it). Although the cost of the alloy rules it out of many applications, sometimes it just can’t be replaced or substituted. It’s that good!
It MEMS packaging, Au/Sn is perfect for Au-Au soldering. The nature of this alloy allows flux-less reflow and strength that is unmatched in the world of solders.
For high-temp (formerly high-Pb temperature) applications, 80Au/20Sn is the only proper Pb solder replacement. As you would expect – this alloy can also be made in preforms, paste, and other forms to replace high-Pb alloys
For us tech guys, I guess recommending Au/Sn is a little like working at a car dealership and letting people test drive a high-end car. If you’re into solder, it just feels good to know someone is using the “Cadillac” or “Ferrari” of solder – Au/Sn