Hello Werner,
Thanks so much for your thoughful comments. What about Roger's
suggestion about the LGA package?
Perhaps that is a compromise for the Mil/aero/high rel industries who
must still use tin-lead?
Roger also talks about copper columns. Please speculate as to what
would be a better package for dense parts such as FPGAs and processors.
FYI, PERM members have developed a proposal for DoD funding of an
intensive R&D effort to solve the many gaps in lead-free electronics
manufacturing. Initially called the "Manhattan" project, it's
estimated to cost $95M. PERM supports the proposal. The Phase I
report is complete (I will email you a copy). Phase II is being
written. Initial funding is from the Navy and has funded subject
matter experts meeting for two weeks in these two Phases (as Denny
explains in his video).
Tim whiskers is one of the identified gaps in knowledge. The Phase I
report indicates that whiskering introduces uncertainties into the
reliability calculation for an assembly. Uncertainties mil/aero/high
performance products such as implanted medical devices cannot tolerate
for their expected life cycle.
What do you suggest part vendors do?PERM has a supplier task team (I'm
a member) and I am proposing we go back to the vendors and discuss
packaging options/changes. Perhaps a fruitless effort but with the
switch to COTS for many formerly MIL devices, RoHS has introduced
reliability problems that need to be addressed.
Sincerely,
Bob
Sent from my iPhone
On Jan 10, 2010, at 3:41 PM, "Bob Landman"
<[log in to unmask]> wrote:
> Hello Werner,
>
> Regarding this issue, I just watched your video at IPC Midwest
> (which was just after Denny Fritz's interview about PERM). Very
> interesting discussion. Regarding the problem with SAC solder balls
> on BGA parts. You expressed the concern (which I share) that
> because they won't supply them "ball-less", high performance
> applications that require tin-lead balls must first remove the SAC
> balls and then reball the packages and that process results in two
> temperature cycles which invalidates the part warranty. You stated
> that you could not understand why parts vendors refuse to supply the
> parts without solder balls.
>
> I attended the 3rd PERM meeting this past week. When the subject of
> BGA SAC solder balls and re-balling was raised, I suggested that
> perhaps the solution was not to re-ball but instead to dispense with
> the use of solder balls. To use tin-lead solder paste to attach
> ball-less BGA parts to PC boards. After all, I surmised, we attach
> QFN packages which have the same kind of pads that BGAs do.
>
> What do you think of this idea? I realize there are a lot more pads
> on a BGA than a QFN but as more and more we go to BGA type packages
> to shrink the size of the package down to the size of the chips
> themselves, don't we need to re-think the use of solder balls?
>
> Some at the meeting concurred with you and said that vendors refused
> to supply "ball-less" BGA packages.
>
> Some suggested that it was a requirement of the parts vendors for
> testing after packaging. I replied that a test socket could be
> constructed which used pogo-pins or similar probing pins to make the
> temporary attachment for testing.
>
> Others were concerned about the mechanical stress that would result
> from eliminating the balls (as a stress relieving agent).
>
> Some agreed that the mechanical strength of the attachment would
> improve, that we would not see the voids that result with SAC solder
> balls
>
> Some were concerned about the reduced clearance of the parts which
> would make the washing away of flux residue much more difficult. My
> suggestion for that problem would be that perhaps the BGA packages
> have to have short pins that are gold plated instead of gold plated
> pads that then have solder balls attached.
>
> It seems to me that a new package is needed now that the industry
> has had to transition to lead-free manufacturing.
>
> I would be most interested in your comments on this idea.
>
> Sincerely,
>
> Bob Landman, President
> Life Senior Member, IEEE
> IEEE Power & Energy/Reliability Societies
> IEEE Standards Association
> H&L Instruments, LLC
> www.hlinstruments.com
>
>
> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]] On Behalf Of Werner
> Engelmaier /*
> Sent: Wednesday, October 07, 2009 3:38 PM
> To: [log in to unmask]
> Subject: Re: [LF] Quality/Reliability of 're-balled' BGA devices
>
> Hi Pete,
> Other than the added cost and voiding the BGA warranties there is no
> down-side i have heard of.
>
> Regards,
> Werner Engelmaier
> Engelmaier Associates, L.C.
> Electronic Packaging, Interconnection and Reliability Consulting
> 7 Jasmine Run
> Ormond Beach, FL 32174 USA
> Phone: 386-437-8747, Cell: 386-316-5904
> E-mail: [log in to unmask], Website: www.engelmaier.com
>
>
> -----Original Message-----
> From: Elmgren, Peter (GE EntSol, Security) <[log in to unmask]>
> To: [log in to unmask]
> Sent: Wed, Oct 7, 2009 10:36 am
> Subject: [LF] Quality/Reliability of 're-balled' BGA devices
>
> Anyone have any experience with the quality/reliability of 're-balled'
> BGA devices? Specifically, any experience with going from a lead-
> free BGA to a leaded BGA?
>
> Thanks,
>
> Pete Elmgren
> GE Security, Inc.
>
> (P) 941-308-8180
> (C) 941-465-8991
>
> www.gesecurity.com
> 8985 Town Center Parkway
> Bradenton, Florida 34202
>
-------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-------------------------------------------------------------------------------
|
