11 Sep
2008
11 Sep
'08
12:43 p.m.
Dave McGuire wrote:
On Sep 11, 2008, at 8:49 AM, Jules Richardson wrote:
I've seen that too! WTF causes that?
I know there's been discussion here about it a few years ago. Possibly
something along the lines of the inside of the IC leg being a different
material to the outside plating, and in some circumstances it can decay much
faster than the outer material.
I'm not sure if there any wisdom as to whether any particular kind of
conditions cause it, or whether it's simply an age-related issue (possibly in
conjunction with a particular manufacturing procedure - I don't recall ever
seeing it* in anything newer than 1980 or so)
* Oddly, I don't think I've come across it in larger chips, either. It's
always been in ICs with smaller pin counts; was the production of smaller ICs
done in a different way during the '70s to ones with higher numbers of pins?
cheers
Jules
I've
started taking the chips out one by one and cleaning the legs by
running them over a strip of scotch-brite. This clears off the
corrosion (and some of these are VERY corroded).
Ugh. I've seen early ICs where the legs essentially rot from the
inside-out; the pins become extremely fragile and prone to just
falling off, and no amount of cleaning makes a good connection.