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July 2012

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From:
"Glidden, Kevin" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Glidden, Kevin
Date:
Tue, 10 Jul 2012 10:51:13 -0400
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[Ahem] I meant WRITE a book, not ride

I can already see this one going out of control.............................

-----Original Message-----
From: Glidden, Kevin 
Sent: Tuesday, July 10, 2012 10:41 AM
To: Glidden, Kevin; TechNet E-Mail Forum; WTSJ-Willis Tam
Subject: RE: [TN] Ionic Contamination Test for Non-clean PCBA, is it really necessary?

I should also add that the IPC-TM-650 Method 2.3.25 test requires a 75/25 mixture of IPA/DI water.  If your no clean has any degree of solubility in this mixture, the test would be detrimental to the whole premise of no-clean: that the potentially harmful (ionic) residues are encapsulated by inactive and inert residues.  There are many people in this forum who could ride a book (some have) about the dangers of doing a bad clean job on an intended no-clean.



-----Original Message-----
From: Glidden, Kevin 
Sent: Tuesday, July 10, 2012 10:34 AM
To: [log in to unmask]; 'WTSJ-Willis Tam'
Subject: RE: [TN] Ionic Contamination Test for Non-clean PCBA, is it really necessary?

I'm certainly no expert, but it sort of fails a logic test - a cleanliness test on a no-clean assembly?

A scan of J-STD-001 sort of indicates this mentality, but does not expressly state it:

From J-STD-001E, section 8:
"An item that is required to be cleaned shall [N1N2D3] be cleaned per a documented process to allow removal of all contaminants (especially flux residue).  The items cleaned shall [N1N2D3] be capable of meeting the cleanliness requirement as specified herein (see 8.3)"

The second sentence does NOT state UNcleaned items shall meet the cleanliness requirement.

However, further in the document it states that unless specified by the user, the manufacturer should specify a cleanliness designator, the letter "C" followed by a two digit code.  The first digit is a 0 (non cleaning), 1 (cleaning one side only), or 2 (cleaning both sides).  The SECOND digit is a cleanliness testing requirement: 0 (no test), 2 (test for ionic residues.  There are other choices for the cleanliness testing code, but "2" would be the digit for your specified test: IPC-TM-650 Method 2.3.25.

So what you are proposing is C00, your customer is proposing C02.  The standard does not expressly state that C02 would be an invalid designator, other than the second sentence from section 8.


-----Original Message-----
From: WTSJ-Willis Tam [mailto:[log in to unmask]] 
Sent: Tuesday, July 10, 2012 2:13 AM
To: [log in to unmask]
Subject: [TN] Ionic Contamination Test for Non-clean PCBA, is it really necessary?

Hi Technet,

We have implemented non-clean SMT and wave soldering processes for more than
10 years and there's no any issue, but recently one of our new customer
required us to buy the Omega tester and set up the Ionic Contamination test
for the non-clean PCBA, according to IPC-TM-650. 2.3.25.   

We feel the Ionic Contamination test might not be an appropriate test for the
non-clean PCBA, but is there any technical paper or industry standard for
this topic? We need some supporting documents for further discussion with our
customer.

Any suggestion/feedback would be appreciated.

Regards
Willis Tam


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