22 Jul
2005
22 Jul
'05
7:01 p.m.
Hi
What kind of package are we talking about?
Plastic can be cut back by about 1/32" to allow connecting
a pin from a scrap IC. ceramic is a little tougher. If the
pin is one of those iron cored pins, you may not be able to
get deep enough to get a non-corroded surface to solder to.
Even ceramics can be carefully solders to and a small amount
of hard epoxy applied to keep the strain off the solder joint
that will be quite small ( epoxy like JB Weld is hard most
clear epoxies are too flexible ).
I have a number of RAM IC that are gradually failing because
they have the iron cored pins. I guess these were cheaper
but electrolysis between the plating and the iron rots them
out from the inside making the pin very fragile.
Dwight
From: "Philip Pemberton" <philpem at
dsl.pipex.com>
Hi folks,
Does anyone know of a way to repair IC pins that have been broken off at
the point where they leave the IC casing? I've got a couple of chips with
missing pins here and was just wondering if it was possible...
Thanks.
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem at philpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI
... Anything not nailed down is a cat's toy
22 Jul
22 Jul
7:28 p.m.
>>>> "Dwight" == Dwight K Elvey
<dwight.elvey at amd.com> writes:
Dwight> ... I have a number of RAM IC that are
Dwight> gradually failing because they have the iron cored pins. I
Dwight> guess these were cheaper ...
Probably not. Chances are the pin is actually made of Kovar or some
other oddball alloy like that. Those aren't cheap at all. Their
purpose in life is to match the thermal coefficient of expansion of
the ceramic, so fast temperature cycles don't break the hermetic
seal. This came out of vacuum tube technology, but it applies to
hermetic semiconductors, too.
I don't believe that Kovar can be soldered, but it probably can be
brazed (with nickel?).
Copper would work quite poorly in that application, because the
t.c.e. of copper is far higher than that of any glass or ceramic.
There are ways around that (see John Strong, "Procedures in
Experimental Physics", a brilliant book) but they aren't all that
appropriate for IC packaging.
paul
7:32 p.m.
In message <200507221801.LAA04557 at clulw009.amd.com>
"Dwight K. Elvey" <dwight.elvey at amd.com> wrote:
What kind of package are we talking about?
PLCC plastic.
Plastic can be cut back by about 1/32" to allow
connecting
a pin from a scrap IC. ceramic is a little tougher.
Yeah, I tried that - Dremel with a micro-drill bit. Shame the bloody thing
skittered off and ripped the lead completely out of the plastic :(
If the
pin is one of those iron cored pins,
Copper-cored, tin-plated on an AMD Am29F040. No big deal - it was mangled in
shipping and the distributor has agreed to send a replacement out. Just a
bit annoying when all the hardware is ready to go and is only being held up
by a Flash ROM :-/
I have a number of RAM IC that are gradually failing
because
they have the iron cored pins. I guess these were cheaper
but electrolysis between the plating and the iron rots them
out from the inside making the pin very fragile.
Eep. Thankfully most of the ICs I've dealt with had SnPb-plated Cu pins (or
Sn-plated Cu).
Later.
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem at philpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI
... Become a programmer and never see the world!!
7118
days inactive
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dwight.elvey＠amd.com -
philpem＠dsl.pipex.com -
pkoning＠equallogic.com