Amol, your peers in the industry the developed and approved the 610D
criteria struggled with this in several meetings. Look in the
acknowledgement pages iii, iv, and v to identify the developers. 

Industry-recognized reliability experts provided support.

It's been my observation in the nearly nine years that I've been staff
liaison to this committee that when data is limited they prefer to take
a conservative approach. That's why BGA voiding remained at 25% in the
face of growing recognition that it is very difficult to correlate
voiding with connection failures. It seems to take more data to change
published criteria than it does to qualify the criteria in the first
place.

I suspect this will hold for hot shrink/tear holes in plated-through
holes assembled with LF alloys. We've received comments for
consideration in the next rev that these anomalies sometimes propagate
in the field. Staff follow-up to such comments is to request data or
even anecdotal comments regarding failures that result from such
propagation. To date, nothing has been provided that the committee can
use to drive changes in the next rev. 

IPC-A-610D is only a visual assessment standard for assemblies, as
stated in the first sentence of the scope of the document. Until such
time as industry has research and data nearly eqivalent to traditional
SnPb alloys, I expect that the 610 committee will continue with their
conservative approach.

Usefullness of the 610 criteria is to establish a defect threshold that
requires assembly analysis to determine usability. The committee members
that provided the hot shrink/tear pictures published in 610D provided
the committee with cross-section pictures of those same tears. However,
as you point out, cross-sections of anomalies that are already visible
doesn't necessarily provide usable data. What the committee is really
looking for is failure data that can be specifically tied to hot
shrink/tear and that can be replicated and used to substantiate changes
in the next Rev.

If your research generates data that the 610 committee can use to
improve the criteria in the next revision, I hope that you will be in a
position to share it.

Cordially,
Jack

Jack Crawford, IOM
IPC Director Certification and Assembly Technology 
[log in to unmask] 
847-597-2893 
FAX  847-615-5693 
3000 Lakeside Drive, Suite 309 S
Bannockburn, IL, 60015

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kane, Amol (349)
Sent: Friday, February 17, 2006 1:32 PM
To: [log in to unmask]
Subject: Re: [TN] Big Holes (no Pun intended) in the IPC610D Criteria
for Shrink/tear holes

Will post the pictures when I get the cross sections... the image I see
under the scope is EXACTLY the same as given in the IPC Criteria...the
usefulness of that criteria starts and ends right there!

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