Is a paste like Solder-It Aluminum Solder Paste ALP-21 suited for electronics? Are there going to be any issues with the solder under constant current due to chemicals in the paste or something like that?
2 Answers
I would not try it.
It is made to solder to aluminum.
Aluminum has a very hard oxide coating, and the flux in the solder paste has to remove it so that the solder can stick to the metal.
That means a very aggresive flux.
The flux used in solder paste for plumbing (copper water lines and such) is too aggressive for electronics - and it only has to deal with copper oxides, which are far easier to remove than aluminum oxides
I expect flux for aluminum to be much harsher than flux for copper.
Plumbers soldering paste can eat the traces right off of your circuit board.
Aluminum soldering paste will probably do the same, but faster.
According to the MSDS, it's just tin with a little bit of silver (0.5%) added. That would be fine for electrical connections.
However, the flux is extremely active in order to deal with the aluminum oxides, which means that I would not want to use it on copper-clad PCBs or normal tinned component leads. It would probably lead to long-term reliability issues.