IPC-600-6012 Archives

September 2009

IPC-600-6012@IPC.ORG

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Subject:
From:
Chris Mahanna <[log in to unmask]>
Reply To:
(Combined Forum of D-33a and 7-31a Subcommittees)
Date:
Tue, 1 Sep 2009 10:46:01 -0400
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Thanks guys!

Pete, I agree that the intent to make a distinction between nonlamination and delamination appears to be the root of the clumsy specification.

Chris

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, September 01, 2009 10:40 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] sodastrawing

Chris,

I think paragraph 3.3.2.10 (in a clumsy manner) is making a distinction between non-laminated and delaminated conditions.  

The first sentence says the "coverilm shall be uniform and free of coverfilm separations."  I would take the use of separations here to mean that the coverlayer was once together (bonded) and is now separated
- this would be delamination.

The paragraph goes on to say that 'nonlamination shall be acceptable, provided such imperfections do not violate 3.3.2.4 and the following...'
I'm not sure why 3.3.2.4 (foreign inclusion) is called out in this paragraph but it doesn't hurt anything.  Then the paragraphs lists 3 conditions, a, b and c.  Of the three conditions I think condition b applies to soda strawing  'b. The total separation shall not exceed 25% of the spacing between adjacent conductors.'

So the difference in my mind is that delamination shows a weakness in the bonding system - that it will (potentially) get worse and propagate to a complete void between conductors.  Non lamination indicates that the  process for cover coating was inadequate - but is not an indication that the bond mechanism is failing.

In a perfect world the fabricator would have seen this condition, documented that it is was caused by using the wrong press pad or something and that the coverlay was deemed acceptable.  Just that little bit of documentation can make their customer feel real good. 

My 2 cents worth...


Pete
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Monday, August 31, 2009 9:41 PM
To: [log in to unmask]
Subject: [IPC-600-6012] sodastrawing

Hi all,

A customer has ask me to query the group about coverlayer sodastrawing.

From the applicable paragraphs in 6013 and 600, one could interpret sodastrawing as completely unacceptable unless it is a "nonlamination" , in which case it can reduce dielectric spacing by 25%.
Unfortunately there appears to be a disagreement about whether sodastrawing is to be included as a nonlamination.

Thanks,
Chris

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