What I have heard is the vendor voids the part warranty if the part is
reballed. I had not heard that there is proof that reballing actually
affects reliability and causes a high failure rate. If this is true does
someone have new FIT rate numbers they are applying to the reballed
parts? How does this affect the MTBF calculations?
Thanks
Tony Cosentino
Tekelec
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Anderson, Richard
Sent: Wednesday, May 24, 2006 11:41 AM
To: [log in to unmask]
Subject: Re: [LF] Reball or not to reball
Just a comment:
It might be that reballing requires an additional several heating cycles
to remove the old balls and replace them bringing the total up to at
least 5 reflow possibilities - the three sanctioned plus removal and
reball. The part may still be good, but if the reliability has not been
documented - then I think no one will guarantee their product.
Hopefully someone has data - it's so much nicer than conjecture.
Cheers,
Dick Anderson
978-442-5165
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of ALLEN, LOA
Sent: Wednesday, May 24, 2006 10:04 AM
To: [log in to unmask]
Subject: Re: [LF] Reball or not to reball
This is the first I've heard of high failure rates from reballing BGAs.
Does anyone have any info regarding the type of failures? Does it have
to do with co-planarity/alignment of the reworked solder balls? Or is
it killing the device through handling, i.e. ESD, excessive heat, etc?
Loa
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of McGee, Mike (MN51)
Sent: Wednesday, May 24, 2006 6:24 AM
To: [log in to unmask]
Subject: Re: [LF] Reball or not to reball
We chose not to allow reballing for just that reason. Most manufactures
will not support reballed parts. If you do reball, make sure you can
test the parts before placing on the board. I know of a shop that was
having approx 25% fall-out of the part they were reballing. I didn't
work directly with them, so I don't have the details, but I heard a lot
about their pain. It was further justification to our management that we
made the right decision. I know several manufactures offer reball "kits"
but for a high-rel environment, I would weigh the risks very carefully
before going down the reball path.
-Mike McGee
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Anslow, Phillip
Sent: Wednesday, May 24, 2006 4:33 AM
To: [log in to unmask]
Subject: Re: [LF] Reball or not to reball
Loa,
My company was planning same strategy of reballing BGAs - in process of
reassessment in the light of following disclaimer from one major
supplier in following link - see page 6.
http://www.xilinx.com/bvdocs/appnotes/xapp426.pdf
Extract for convenience: "Xilinx does not recommend reballing. Xilinx
parts that are reballed will not be guaranteed by Xilinx. A maximum of
three reflow cycles are allowed."
Not sure if this is isolated or general across component suppliers.
Suggestions for high-rel welcome...
Regards,
Phil.
-----Original Message-----
From: ALLEN, LOA [mailto:[log in to unmask]]
Sent: 22 May 2006 20:57
To: [log in to unmask]
Subject: Re: [LF] Reball or not to reball
*** WARNING ***
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Keep this in mind if you answer this message.
John,
Thanks for the reply . . . you pretty much answered my question
regarding the BGAs. We plan to replate/pre-tin the leaded comps because
of tin whiskers. However, guess I was looking for some reassurance that
re-balling the BGAs was the best course of action to take & was
wondering what others are doing.
Also - thanks for being the voice of the silent majority with Pushback.
Loa
-----Original Message-----
From: John Burke [mailto:[log in to unmask]]
Sent: Monday, May 22, 2006 9:45 AM
To: '(Leadfree Electronics Assembly Forum)'; ALLEN, LOA
Subject: RE: [LF] Reball or not to reball
HI Loa,
I will let others advise on the rest but you will have to re-ball those
BGA's if you are going to solder them using leaded solder.
There is a lot of published work, if you need examples ping me off line.
John
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Loa
Sent: Monday, May 22, 2006 9:22 AM
To: [log in to unmask]
Subject: [LF] Reball or not to reball
Is there a consensus among the listserv on using Pb-free comps in a SnPb
assembly?
We are a U.S. OEM claiming exemption to the RoHS directive (design & mfr
of data storage/transfer equipment with no current EU customers) and as
predicted, the supply of SnPb terminated components are drying up with
many of the new design comps not even being offered in SnPb. Based on
the published work of industry experts and monitoring of the IPC LF &
TechNET listservs, we have decided to "hot solder dip" Pb-free SMT comps
with legs and re-ball Pb-free BGAs (both with Sn~60/Pb~40); vastly
increasing the cost. Our assemblies are very low volume (5 to 15pcs
typ) with a large mix of complexity and assembly part numbers.
I have queried local contacts in similar industry/situations and
received the deer-in-the-headlight stare. I have sat through workshops
explaining how uncertain the future is regarding varying interpretations
of reliability - I just thought I was confused before.
My Other Question: What is the opinion of the masses - are we doing our
product unjust harm in an attempt to maintain reliability? We are
willing to deal with the cost of re-plate/re-ball as long as performance
and reliability are unchanged.
TIA (not the dog)
Loa
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