What type of solder is used on circuit boards for space probes?

[xrunner]

That's my question for today. Thank you.

[NiHaoMike]

Most likely some very high grade leaded silver solder. Space hardware generally uses tried and true processes and materials since reliability is top priority.

[CatalinaWOW]

The OP in this thread listed below links a NASA paper related to this subject.  Generally NASA requires something like 2-3% lead in the solder.  The paper describes why.  I believe the other space agencies have similar policies.

https://www.eevblog.com/forum/projects/whiskers-on-components-worth-a-read/msg996258/#msg996258

[ConKbot]

From nasa-std-8739.3
 
6.11 Solder
6.11.1 Types and Usage. All solder used for tinning and solder connections shall conform to
ANSI/J-STD-006 (Requirement). Flux-cored solder shall be either composition SN60 or SN63
containing flux types R or RMA, or equivalent (Requirement). For all soldering applications
where adequate subsequent cleaning is not practical, only solder containing flux type R shall be
used (Requirement). Solid solders (no flux) for use in solder pots shall be of the same
composition (Requirement).

[Stray Electron]

   I don't know what they're using now but about 5 years ago they HAD been using lead-free ROHS solder and they lost a LOT of satellites due to that stuff.  I live with a few miles of KSC and a friend of mine had a job removing the lead free solder and re-soldering the circuit boards with leaded solder.  I don't know what alloy though.

[xrunner]

Thanks for the answers. 

[German_EE]

I was at a place on Thursday that made space qualified parts and they used leaded solder.