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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