Thanks for your comments, John.
For clarity, I wasn't attempting to compare integrity of voids in BGA
connections to LF hot shrink/tears. I was just providing two examples of
converative criteria in 610D.
I saw something earlier this week in an e-zine article regarding the 3%
return rates, but I don't recall the article referencing failures from
hot shrink/tears. The committees ultimately will need more than summary
statements. IPC-9701 Performance Test Methods and Qualification
Requirements for Surface Mount Solder Attachments is applicable to all
connections, including LF. As use of this standard increases we'll get
more data I'm sure.
IPC-7912 End Item DPMO, and IPC-9261 In-Process DPMO are the only
published industry consensus DPMO standards. Both documents use the same
defect code list. Additional value would come from users of these
standards documenting whether their DPMO data was accumulated from
assemblies made with SnPb or LF alloys.
Thanks again for your ideas.
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: John Burke [mailto:[log in to unmask]]
Sent: Friday, February 17, 2006 7:20 PM
To: TechNet E-Mail Forum; Jack Crawford
Subject: RE: [TN] Big Holes (no Pun intended) in the IPC610D Criteria
for Shrink/tear holes
Good afternoon Jack
The difference here is I guess that the nature of voiding in BGA's is
generally tending towards spherical.
In the defect cases that Amol is talking about I suspect they are
anything but, and more likely to act as a stress riser.
I suspect your failure data may be forthcoming very soon Jack.
I have seen this week reports that one manufacturer has experienced a 3%
return rate increase of shipped product since going lead free, and that
was 3% of the product shipped not 3% increase in RMA.
Since we are effectively in the position of EEC dictating to a global
electronics market - and yes I DID SAY DICTATING, we are in effect using
the whole world of electronics manufacturing sector as a "global beta
site test".
IPC 610 committee might want to think about throwing together a quick
classification number/letter system for lead free specific defects so
that the data coming in will be granular enough and unambiguous enough
to see what is happening in real time.
This could be done in much the same way that the SMART group set up
their PPM defect reporting system some years ago.
Time for action is now rather than try to address it once the patient is
dying.
John
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Crawford
Sent: Friday, February 17, 2006 5:00 PM
To: [log in to unmask]
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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