[sdiy] keyboard contacts

[john mahoney]

Fabio,
This is really a hardcore DIY project. Good luck with it.

Copper is an excellent conductor but can get corroded easily (or, is it just
the copper/zinc alloy of which U.S. pennies are made that corrodes so
much?). With corrosion, the bouncing will come back again very soon,
especially on keys that are seldom used. How often do you want to polish the
contacts?! :-)

Many switches, keyboards and high quality jacks & plugs use gold contacts
because gold is a very good conductor and it does not corrode. I think
nickel plated copper is also used -- much cheaper than gold. Silver is more
conductive than gold and a lot cheaper, but it corrodes (tarnishes) so much
that it is not good for this purpose. I am not suggesting that you make your
contacts from solid gold! But you need to choose the metal wisely.

Also, keyboards and switched are often advertised as having "self-wiping
contacts." Try to make your contacts self-wiping. When you press a key its
contacts will try to wipe any dust (or corrosion?) off of each other. Theis
means the contacts must slide against each other as they make contact. This
also means the contacts will flex a little bit each time they make contact.
As far as I know, copper is not very good for springs, either. I think this
is called "work-hardenable," so it breaks if you bend it too many times.
(Hey, I found some info on Electronic Connector Alloys at
http://www.connector.org/, but I need to go to bed, so no time to read it
now.)
--
john

[snip]
> - Will it worth the effort to hand-make all the contacts?
> - Does anyone in this list made it before?
> - Did they work as expected?
> -  ...even after a year?