Microsoft InPort mouse

[resabed01]

I was busy scrapping my mountain of electronics today and I cracked open a old Microsoft InPort mouse and found some interesting switches inside.
These mice were used on early PCs and needed a special ISA adapter card to work. These were used before the standard serial port mouse came out.
Anyways, inside I found two Alps roller switches. I busted one open to find a disc with a pattern printed in gold with no copper underlay.
On the tip of each of the three contacts is two tiny silver colored wires which I'm hoping is Platinum 8)
I must have tossed several of these out over the years. Now I wish I looked more carefully.
Here's a picture

 

[ericrm]

why do you think there is no copper under the gold on your disc?

 

[resabed01]

Copper is usually quite thick on PCBs. You can feel it with you fingernail as well as see it. This pattern layer is very thin on the disc. Also I looked at the broken edge with a magnifying lens and couldn't see a base metal.
I admit, it's not much but the gold layer is thick enough to resist the wear from the contact wires. I'll throw them in with my batch of fingers next spring.