There are a lot of parameters to consider when choosing the right solder for your application:
1) The operational temperature of the final device
2) The metallizations that you are soldering to
3) Temperature sensitivity of any components that you are soldering
5) Drop test requirements
6) Reliability requirements
Each individual application will, no doubt, have additional requirements. But, generally, one of the first considerations will be the melting temperature of the solder.
Many applications need a low-temperature solder that will reflow below 180C. For example, LED attach, optics assembly, and MEMS mounting all have low temperature solder requirements. There are two metals, in particular, that help fulfill this need. One is indium and the other is bismuth.
There are five common solder alloys that are well suited for your low-temperature, Pb-free requirements. As a matter of fact, they are so popular we have packaged them together in a kit (in the solder paste version) for you to evaluate.
Our Low Temperature Pb-Free Solder Paste Research Kit allows you to evaluate any two alloys in a side-by-side comparison to determine the optimum paste for your application. The five alloys that you can choose from in our Low Temperature Pb-Free Solder Paste Kit are:
- Indalloy 1E (52In 48Sn) Eutectic at 118C
- Indalloy 281 (58Bi 42Sn) Eutectic at 138C
- Indalloy 282 (57Bi 42Sn 1Ag) 140C/139C
- Indalloy 290 (97In 3Ag) Eutectic at 143C
- Indalloy 4 (99.99In) Melting Point of 157C
In this kit, each alloy is matched with the proper flux vehicle so you can comparatively test multiple alloys to see which is the best option for your application.