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July 2008

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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, 18 Jul 2008 09:05:14 +0300
Content-Type:
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text/plain (68 lines)
This is just another example (all too common in our industry) where 
rigid adherence to standards negates common sense.

Ask yourself what ionic contamination testing is for. Is it a process 
control for your soldering/cleaning operations? Is it an insurance 
policy for the correct application of conformal coating? If the answer 
to both questions is yes, then, if the two operations are spaced in 
time, you must do it twice, not once (on different boards!!!!)

Brian

- bogert wrote:
> July 17, 2008
> 
> J-STD-001D, paragraph 8.3.6 requires that, if cleanliness testing is 
> mandated, the testing must be performed after final cleaning (i.e., 
> prior to conformal coating).  We have an OEM who performs cleaning 
> within 1/2 hour after wave soldering.  The OEM also does post hand 
> soldering after wave soldering and does local cleaning of the hand 
> soldered joints in max 1/2 hour after soldering.  However, several days 
> or weeks may pass between the wave soldering and hand soldering 
> operations before conformal coating is done.  The OEM does the 
> cleanliness test just prior to conformal coating as is mandated by 
> J-STD-001 since the cleaning after hand soldering is the "final cleaning 
> operation".
> 
> My question is since the cleanliness test is not done until several 
> weeks after wave soldering/post wave soldering cleaning was done, will 
> the ionic cleanliness testing mandated by J-STD-001 (standard instrument 
> test like Omegameter) be caple of detecting ionic contamination?
> 
> Seems to me that if the cleaning process is having problems, harmful 
> Type M or H flux residue, if not completely removed by the cleaning 
> process, may solidify to the extent that the DI water/Alcohol 
> cleanliness test may not be capable of dissolving the hardened residue 
> precluding detecting ionic contamination.  Is this a valid concern or 
> not?  Is there any data that shows the ability of the test equipment to 
> detect ionic residue over time since cleaning?  Do we need to make any 
> changes to J-STD-001, paragraph 8.3.6 based on my question? If so, 
> please propose recommended wording for the change.  Thanks for your 
> support.
> 
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