[Coco] How do you clean oxidized IC legs?

Gene Heskett gene.heskett at verizon.net
Sat Apr 18 23:32:39 EDT 2009


On Saturday 18 April 2009, Steven Hirsch wrote:
>On Sat, 18 Apr 2009, Christian Lesage wrote:
>> I've been restoring a few classic computers lately, and I found that some
>> ICs (especially TI and MOSTEK ones) had their legs so much oxidized that
>> they turned black. What is the best way to clean those legs?
>
>If they're really that bad, put a little drop of brass polish on the end
>of a Q-Tip and roll it against the leads from both sides.  You may have to
>use a couple if a lot of gunk comes off.
>
>If you are in a low-humidity situation, work on a piece of tinfoil and
>make sure your hand or wrist is in contact with it and the chip to keep
>you at the same potential.
>
>Works like a charm.
>
>Steve

'tinfoil'=aluminum foil.  And the breakdown voltage of the alu oxide that 
forms on it when its scratched, about .001 second after the tool that 
scratched it has passed, has a breakdown voltage of about 50 volts.  Aged as 
it comes off a roll of Reynolds wrap, it could be as high as 400 volts.

Little or no effective static control can be found in that.  The best deal I 
ever had was a semi-conductive brown rubber mat that I picked up on sale, 
24x36", for about 30 bucks, 15 years ago.  I think it is still on the 
workbench at the tv station.  I never damaged a chip while working on that.  
I'd blown 2 the week before I got it, working on a benchtop with that white 
masonite on it.  Even in bad shape, that stuff was hot. 10kv just from sliding 
a dry, bare hand over it.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
For men use, if they have an evil turn, to write it in marble:
and whoso doth us a good turn we write it in dust.
		-- Sir Thomas More




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