From my past experience at another company, I would say that your BGAs will
likely pass 5DX inspection today - balls do not melt though. However, over
the long-term, intermittent signal errors popped up that were later found to
be caused by the lead-free BGAs. We had to do a lot of re-work.
Of course, your experience may differ depending on board size, thickness,
component density, etc., etc.
Most manufacturers who have posted some sort of leadfree/ROHS statement on
their website say that all lead-free packages EXCEPT BGA & MLF are backwards
compatible to be used in the standard leaded process.
The only exception I've come across being this document but they still
suggest higher reflow temperatures - which may damage your other
Pb-containing components that have not been rated to the higher reflow
temperature (see pg.7, table 2):
http://www.infineon.com/cmc_upload/general%20recommendations%20for%20board%2
0assembly%20of%20lead-free%20BGA_2_0.pdf
I'd suggest you go after the other 20% of components that you need to
convert to lead-free (and don't assume that a manufacturer who has a
lead-free component has also gotten around to qualifying it to withstand the
higher reflow temp.)
Good luck!
rgds,
Suzie
-----Original Message-----
From: Carol Spiers [mailto:[log in to unmask]]
Sent: Tuesday, December 07, 2004 1:45 PM
To: [log in to unmask]
Subject: Re: [LF] Transition questions, Pb to Pbfree wave soldering ??
I agree that Lead Free has to be a consious Lead Free effort in the process
of assembly, however, the transition issue is potentially compromising
current assembly processes and reliablity of products.
Here's a real life scenario relative to smt processing that I am living
with.
I currently have a board that is populated with SnPb smt parts, our sole
sourced supplier has converted the BGA we use to a new lead free version. I
had the choice to
a) change my process to high temp SnPb solder at smt (and adjust oven to
higher temp and assume I am still within the parameters of the thermal
limits of all components on board) to help ensure joint reliability or
b) convert the whole smt process to lead free paste and silver emersion
boards and subsequently adjust ovens to even higher temp, (at this point not
sure if thermal limits on all parts can withstand the potential 20 Deg C
adjustment).
I opted to go with
c) ran the BGA in my current process with no adjustments.
We have completed all functional testing with no failures, but I still feel
there is a long term reliability risk. I have sent samples of the completed
boards to a lab for xray and cross sectioning and comparison evaluations to
determine long term reliability.
I haven't received the results back yet.
What would you have done?
Any and all suggestions greatfully received.
Thank you
Carol
C. M. (Carol) Spiers
Director of Operations
Interalia Inc.
-----Original Message-----
From: MA/NY DDave [mailto:[log in to unmask]]
Sent: December 07, 2004 10:59 AM
To: [log in to unmask]
Subject: Re: [LF] Transition questions, Pb to Pbfree wave soldering ??
Hi Rick, IPC LF Listservers,
Gee I hate to say Duh Rick since this a US term, and I don't really
remember when this "Duh" first started. 80's in the USA I think. Hey EU'rs
do you have a Duh! across the pond, or how about your FarEastAsianers?
Lead Free has to be a consious Lead Free effort in the process of assembly
if you intend to market and mark your product as Lead Free.
Yours in Engineering, Dave
YiEngr, MA/NY DDave
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