Re: Cleaning corroded chip pins

On Sat, 29 Jan 2005 11:03:28 EST, you wrote:

>Yup. Use one of the many tarnish removers that come in liquid form.
>Stinks like Sulfer! Wash the board after. Technically, is there any
>reason to clean chips pins if they are tarnished? Obviously, rusted
>pins have their own problem and tarnished to the point of weakness is
>also obviously problematic.

If the pins are tarnished, they won't make good contact in the sockets.
('Course, the socket pins might well be tarnished by now, too!) It doesn't
matter so much on the upper, wider portion of the leg right where it goes
into the chip, but the thin bit that goes into the socket itself needs to
make good contact or you'll have all kinds of fun problems.

Those triple-damned four-digit custom IC's used by Namco are _really_ bad
about this, but I've seen a lot of ROM and RAM chips do this, too. (A lot
of 70's-era TI stuff seems to be prone to this as well, but that just might
be my own particular run of luck with them. :) ) As valuable as those
custom chips are, I've taken to preserving them by getting DIP headers of
the appropriate size, soldering the customs to the DIP headers, then
_thoroughly_ cleaning away all of the solder flux and coating the legs with
three or four coats of clear nail polish to seal them.

Replacing those cheap PCB sockets with some good, high-quality machined-pin
ones would be a good idea, too... just be really careful about how much
force you apply to get those chips back in! Remember, every time you clean
those pins, you're shaving a few more atoms' worth of thickness off those
pins, and they're not that thick to begin with... :) (Which is another
good reason to mount those valuable custom jobs onto DIP headers.)
-------------------------------------------------------------------------------
Scientists decode the first confirmed alien transmission from outer space...

"This really works! Just send 5*10^50 atoms of hydrogen to each of the five
 star systems listed below. Then, add your own system to the top of the list,
 delete the system at the bottom, and send out copies of this message to 100
 other solar systems. If you follow these instructions, within 0.25 of a
 galactic rotation you are guaranteed to recieve enough hydrogen in return to
 power your civilization until entropy reaches its maximum!"
-----------------------------------------------------------------------------
solarfox@DON'TMESSWITHtexas.net (Gary Akins jr.)
http://lonestar.texas.net/~solarfox
-----------------------------------------------------------------------------

---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com
Received on Sat Jan 29 13:44:13 2005