----------
> From: Doug Pauls <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: [TN] FAB:  HASL vs. anything else -Reply -Reply
> Date: Friday, January 30, 1998 10:38 AM
>
> In a message dated 98-01-27 09:04:21 EST, you write:
>
> >
> >  The IPC limit for contamination is 10.07 ug / sq in NaCl equiv.    The
3 ug
> >  limit is good for no-clean, but naturally the cleaner the better.
> >
>
> It should be pointed out that the historical 10.06 figure was for
finished
> assemblies, processed with high solids rosin fluxes.  For bare boards,
MIL-
> P-55110 (or was it 28809?) had a value of 5.5 micrograms of sodium
chloride
> equivalence per square inch.  IMHO, both are a crock.
>
> These limits have been so abused and applied to so many inapproprate
places
> that it is not funny (one of my favorite pet peeves).
>
> A better measure of board and cleanliness is ion chromatography
(IPC-TM-650,
> method 2.3.28).  For this, we advise bare board cleanliness of less than
2.00
> micrograms of chloride per square inch and less than 15 micrograms of
bromide
> per square inch.  These measures are NOT THE SAME as the ROSE measures
above.
>
> More information on these will be available on our web page, assuming I
can
> get the host service to get it in place in the next week or so. (A
nightmare).
>
> Doug Pauls
> CSL
>

I agree with you to some extent.  However, IC is an expensive
test.  I think 3 eq. micrograms NaCl / sq in measured by
Phil Whitmer's modified ROSE test, which uses the same
extraction method as the IPC IC test would be just about as
good as 2 microgram Cl- /sq.inch by IC.

Modified ROSE is a much cheaper test, all that is needed is
isopropanol, DI water, KayPak bags, a hot water bath, a
solution condutivity meter and a standardizing NaCl solution.
Any PC fab. or electronics assembly shop can do it on
a routine basis.

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