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