How did MOS design and photomask technology evolve?

[Tor]

dwight wrote:

Wires, aluminum or gold, were put down with sonic welders, not soldered.

Well, I was joking, of course.

[kakemoms]

The ball bonder we have is a general wire soldering machine that uses High voltage to form the ball, then ultrasound to weld it in place. The standard wire is 25mil gold.

Edit: Also from my experience on decapping a 6560, it was bonded with gold wires of approximately the same size.

I also found a MOS 2050 SRAM wafer on ebay:

MOS2050 wafer

Too expensive for me, but the seller claims that its a 2inch wafer from 1970.

[kakemoms]

I have also located full wafers of 6502, 6510 and 6561. I am waiting for details about size and revision. They are all very expensive.