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February 2012

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Brian Ellis <[log in to unmask]>
Date:
Fri, 17 Feb 2012 00:47:31 +0200
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These 'equivalence factors' were about the most stupid thing that ever 
came out of MIL specs (MIL-P-28809A, to be precise). They were 
absolutely meaningless, like calibrating a micrometer with a wooden foot 
rule. It tried to reduce the instruments down to the level of the spray 
from a wash-bottle test which alone could easily introduce errors of 48% 
or more. Furthermore, the instruments it refers to were those of 1981, 
which bear absolutely no resemblance to those marketed today.

I refer you to Bergendahl and Dunn 'Evaluation of Test Equipment for the 
Detection of Contamination on Electronic Circuits', European Space 
Agency Technical Memorandum ESA STM-234, Paris (1984). This document not 
only verifies that the notion is nonsense, but that the so-called 
'equivalence factors' for each instrument varies greatly with both the 
flux and cleaning process used.

This notion of 'equivalence factor' should be relegated to the 
oubliettes once and for all.

Brian

On 16/02/2012 21:59, Richard Kraszewski wrote:
> While I realize that IPC specifically and the industry in general, does not support the use of ROSE correlation factors for the various testers, I have a need to see the official document that at one time quoted these specifically allowed factors.
>
> I took a cursory look though all 230 pages of IPC TR 583 and didn't see that table.
>
> I seem to recall a military specification that had that table. Was it 454? 28809, 2000?
>
> Does anyone recall?
>
>
> Rich� Kraszewski / PLEXUS
> �
>
>
>
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