[sdiy] black flaky chip legs: what does this indicate?

[S Ridley]

Were the blackened legs on Texas chips?   I've seen a lot of this on ICs
from the late 1970s or early 80s.

I heard that Texas offered different grades of plating for ICs which were
meant to be soldered or socketed - less plating on the ones which were
meant to be soldered.  As these were cheaper...  well, guess the rest.
 While I can't confirm the story is true, it ties in with what I've seen.



Steve









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On Sun, 1 Nov 2020 at 19:21, Kenny Balys <kenny at beatkamp.com> wrote:

>
> I completed a repair and had two 74LS138's with blackened
> legs. I went to pull one and it came apart. The legs are
> degraded somehow. Then on to the other 74LS138: same.
> The legs of the IC's just fell away.
>
> What could have caused this?
> Has anyone seen something like this?
>
> There is no Varta battery pack on the board. I have seen
> something like this on a Poly-Six.
>
> Other IC's near these two were not the same. The circuit
> board seems to be ok.
>
> The instrument is now functional after replacing the
> two 138's and changing a few caps.
>
> Thanks in advance for any ideas.
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