22 Jun
2000
22 Jun
'00
1:58 p.m.
It was the gold eutectic weld that was the source of
alpha particles
that were the concern at the time.
No. The weld was not a problem. The ceramic emitting alpha particles
was a problem. This was solved by adding or changing the passivation layer
on the top side of the die. It doesn't take much to stop alpha particles.
The die and lead frame are thick enough that alpha particles from the ceramic
on the bottom of the package don't affect the memory.
However, alpha particles didn't start to be a problem for DRAM until
the 64Kbit generation.