Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing
941 Route 38 Owego, NY 13827
Phone: (607) 687-7669 x349
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-----Original Message-----
From: Kane, Amol (349)
Sent: Monday, February 20, 2006 7:35 AM
To: 'Jack Crawford'; [log in to unmask]
Subject: RE: [TN] Big Holes (no Pun intended) in the IPC610D Criteria for Shrink/tear holes
Dear Jack and Technetters,
Thank you for the descriptive e-mail and explanation of the rationale behind the criteria (from jack) and overall response from the group. I plan to do the x-sections this week, and shall keep everyone posted on the outcomes.
Sincerely,
Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing
941 Route 38 Owego, NY 13827
Phone: (607) 687-7669 x349
[log in to unmask]
-----Original Message-----
From: Jack Crawford [mailto:[log in to unmask]]
Sent: Friday, February 17, 2006 8:00 PM
To: [log in to unmask]; Kane, Amol (349)
Subject: RE: [TN] Big Holes (no Pun intended) in the IPC610D Criteria for Shrink/tear holes
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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