removing parts from PCBs

[Allison]

>
>Subject: Re: removing parts from PCBs
>   From: Paul Koning <pkoning at equallogic.com>
>   Date: Wed, 16 Nov 2005 09:24:01 -0500
>     To: cctalk at classiccmp.org
>
>>>>>> "woodelf" == woodelf  <bfranchuk at jetnet.ab.ca> writes:
>
> >>> Is that the stuff in Cray's?  Now we know why they are so much!
> >>> 
> >> A relative, but not the same stuff.  Cray used Fluorinert F-77,
> >> which boils at about 203F.
>
> woodelf> So what is wrong with cheap water?  I guess - inert - says
> woodelf> it all.
>
>Water is not inert, especially not when hot.  
>
>      paul

The real problem with water is not it's conductivity.  High power 
tube transmitters have used distilled water in the past as it's a 
really poor conductor if kept clean.

DEC experimented with water cooling too. The Aquarius project was
a water cooled VAX.  Too many headaches with leakage, heat transfer
to the environment and installation issues.  Systems like that use 
a chiller and heat exchanger to cool the closed loop water system.
Those are costly and difficult to install.  Murder if it should leak
in a computer room. Then there is an efficientcy problem as you end 
up using power to move heat which adds heat.. 

With all that, the circuits they were trying to cool were getting more
power efficient.  So by time they worked out wet cooling air cooling
was again attractive or at least far easier.

It's still packaging.  ;)


Allison