I tried an experiment today which was completely successful and the info may be of use to some.
I have a small quantity of GALINSTAN which is an eutectic alloy of gallium, indium and tin (hence the name GAL(lium), IN(dium), STAN(num). Galinstan freezes at -19 degrees C, so it's liquid metal at normal room temperatures. Nice thing about it is that it's non-toxic.
The point of this post..... I connected an ordinary snap-action microswitch to 5 volts through a 1000 ohm resistor and connected it to my silly-scope to look at the contact bounce. Of course I had bounce galore!
Then I "tinned" the microswitch contacts with some Galinstan. Not even a drop, just enough to "wet" the contacts and make them shiny.
I reassembled the microswitch and tested the performance again. Absolutely ZERO bounce!
Looking at the contacts with a digital camera set to 8X speed, I looked at the contacts as they opened and closed. Upon closing, they just come together. Upon opening, there is a microscopic "string" of Galinstan which forms between the contacts. The string is only a fraction of a millimeter long and VERY thin. As the contacts come apart, the little string breaks and gets "sucked back" onto each contact (if all this makes any sense)?
Attached are scope screenshots of the switch performance.
(click thumb for full size)
So, if anyone needs to make a switch that has zero bounce (and probably is more reliable due to the constantly reforming liquid metal contacts), get yourself a gram or so of Galinstan and try wetting your switch contacts!
I bought mine from a place called "RotoMetals", but it can be found other places (as well as home made - just get a bit of gallium and indium - you really don't need the tin) and just melt the two with boiling water and mix the proper ratio.
Be careful with it, it's SUPER messy. The tiniest drop will stain everything a gray-black (especially skin - it's not toxic but it's MESSY!). And, if you wear a wedding ring or any other gold - be sure to remove it before handling Galinstan. It will "tin" gold and it's impossible to remove it from the gold without using an acid to dissolve it. Be sure to wear no gold during handling the stuff, and wash your hands afterwards to avoid transferring any Galinstan to the gold.