Testing large number of processors

[keith]

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On Sat, 21 May 2005 18:25:08 +0000, Robert Redelmeier wrote:

> Del Cecchi <dcecchi.nospam@att.net> wrote:
>> Nanogram? I don't think so.
>
> Don't think about numbers -- calculate!
>
> How much gel is left after wiping? Max 5um on the flat top
> and 15um on the edges? That gives 800 nL or 800 ug. At 0.8%w
> NaCl, that is 6400 ng. Call it low microgram if you wish.
>
> Think if it a different way. You apply about one drop (50uL).
> Good cleaning should remove 98+% leaving 1000 nL or 8000 ng.
>
>> And look up Sodium and threshold instability.
>> Goes back aways.
>
> I did and got no good hits on Google. Can you be
> more specific? Certainly sodium can contaminate printed
> semiconductors, but it's got to get there. How is it going
> to migrate through 1+mm resin or 0.5 mm hi purity silicon?

A couple of atoms in the wrong place is 'nuff. Sodium is nasty stuff, as
anyone living in the North can attest to.

--
Keith

 

[keith]

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On Sat, 21 May 2005 22:19:41 +0100, GSV Three Minds in a Can wrote:

> Bitstring <pan.2005.05.21.18.39.50.993377@att.bizzzz>, from the
> wonderful person keith <krw@att.bizzzz> said
> <snip>
>
>> Perhaps some zinc-oxide sun block?
>
> Why would you bother when you can get Zinc Oxide 'generic' thermal paste
> in litre pots for a few shillings? I mean you really don't have to use
> the latest Antarctic-Palladium-Ceramic-Version 6b. In fact is doesn't
> make a degree difference anyway, if the HS is actually flat.

It's really the same stuff. Sun-block is easier to find though. Look for
the lifeguards with the white noses. ;-)

--
Keith

 

[keith]

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

On Sat, 21 May 2005 20:48:18 +0000, Rob Stow wrote:

> keith wrote:
>> On Sat, 21 May 2005 01:44:40 -0600, A Jones wrote:
>>
>>
>>>On Fri, 20 May 2005 21:44:51 +0000, Robert Redelmeier wrote:
>>>
>>>
>>>>No fan is much easier than no paste. The fan is only needed after
>>>>the block heats up, and that takes minutes. For a temporary TIM,
>>>>I'd suggest Vaseline (microcrystalline petroleum wax) if there
>>>>are exposed electrical points on the CPU topside, or K-Y Jelly
>>>>(thickened isotonic saline) if there are no conductivity issues.
>>>>The water in the latter is an _excellent_ thermal conductor.
>>>
>>>So let's say I go with Vaseline. Then there's no controversy about
>>>whether the saline is a problem. Can I use Vaseline as a cheap
>>>substitute for thermal paste that's adequate for a post or
>>>even a boot to Windows?
>>
>>
>> As I said before, what about zinc-oxide sun-block? You should be able to
>> buy that stuff by the pound.
>
> Why not a flat-bottomed steel bottle full of liquid nitrogen ?

It is cheap stuff, but it's a little hard to handle for such things.
Besides, there is such a thing as *too* cold. Yes, Liquid Nitrogen is
often used in testing, but water is easier unless testing at the low
extremes (0C, for commercial) is needed. For these purposes air should
work fine though.

> Set it on processor, test, lift it off. Repeat with next CPU. You
> can|should insulate the walls of the bottle so that the nitrogen lasts a
> little longer.

Too cold could cause all sorts of problems.

> With something nice and cold like that a perfect fit between the CPU &
> bottom of the bottle shouldn't be necessary for a simple one or two
> minute test.

Exactly. Why go to this extreme though.

--
Keith