Joe:
At the beginning of the J-STD-001 paragraph that you cite,
it specifies the test method, which is IPC-TM-650, method
2.3.25C. If you look at that document, it talks about
the fact that instruments give different readings, and
directs you to IPC-TR-583 for further explanation.
What this means is that 1.56 micrograms/cm2 will
measure differently on different equipment. Historically,
we've used the equivalence factor from MIL-P-28809, so
our acceptance limit is 14 micrograms/in2. Even
though we use the 600SMD, which is a different model,
and uses heated solution, we've kept that limit, because
1. (Most importantly) we don't have any problem meeting it.
2. The old 28809 is the only DOD document extant that gives
us any number at all.
3. This is a complicated subject, and if we tried to change
the number, our customers might require a lot of explanation.
4. The real purpose of the instrument is process control,
and the limit doesn't mean much anyway.
By the way, the TR-583 has a lot of good information.
-Joe
-----Original Message-----
From: Joe Russeau [mailto:[log in to unmask]]
Sent: Wednesday, October 26, 2005 11:21 AM
To: [log in to unmask]
Subject: Re: [TN] Omegameter to IPC-TM-650, Method 2.3.25 cross
reference
Hi Joe,
I have reviewed rev D of J-STD-001 (don't have Rev C), in section
8.3.6.3, it says "for assemblies soldered with ROL0 or ROL1 fluxes, the
surface contamination shall be less than 1.56 micrograms per square
centimeter NaCl (approximately 10 micrograms / sq. in) equivalent ionic
or ionizable flux residue". I do not see in the Rev D version ( I would
assume it is similar in the Rev C) where a particular piece of equipment
is specified. Thus, I would conclude that adjustments to that value are
not warranted, unless you and your customer have agrred to a different
value. I will grant you that not all pieces of equipment measure the
same on all occassions ( too many variables to discuss, perhaps another
discussion), but the Omegameters I have worked with have standardizing
solutions that can be purcahsed. Standardizing the machine before
testing to make sure it is measuring correctly is always a good
practice, but changing the recommended value just because you are using
an Omegameter instead of an Ionograph, not enough justification for me.
My 2 cents.
Best Regards,
Joe Russeau
Process Analyst
Precision Analytical Laboratory, Inc.
4106 Cartwright Dr. Ste. A
Kokomo, IN 46902
P: 765-455-1993
F: 765-455-1996
E: [log in to unmask]
----- Original Message -----
From: "Macko, Joe @ IEC" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 26, 2005 9:27 AM
Subject: [TN] Omegameter to IPC-TM-650, Method 2.3.25 cross reference
> Fellow techs,
>
>
>
> Good morning.
>
> We have an Omegameter 600SMD that is used to check boards for ionic
> contaminates. The ionic residue limit within J-STD-001C, para. 8.3.6
> is
10
> ug/sq. NaCl. Some personnel believe that this number should be
> adjusted based on the actual instrument used (e.g., an Omegameter).
> Would someone
be
> so kind as to comment on this subject and what the correct limit is
> for an Omegameter type of instrument.
>
>
>
> Thanks
>
> joe
>
>
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