All -

I wanted to repost a question by Blair Hogg.  Please see below.

Does anyone have any data and/or study results that they wouldn't mind
sharing related to the process of mixing lead free components with tin/lead
paste?

Any practical, real life experiences anyone would like to share?


Another question:
From my research, I have gathered that current PCBs used for the standard
tin/lead process may or may not be acceptable for lead free processing.
Items to consider when evaluating whether or not these boards are acceptable
for use include board complexity, rework potential, single vs. double sided,
etc.  The only way to determine acceptability is through process evaluation.
Is this a correct assumption?  Or am I way off the mark here?

Little bit about my organization: OEM memory supplier, surface mount only,
no clean, range from very simple to very complex memory boards....  pretty
straightforward stuff.


Yet another question:
This may seem like a silly one....  but is it acceptable to run lead free
product on the same production line as non-lead free? Through the same oven
as non-lead free product?  Other than extensive cleaning of printers, and
tight inventory/product controls, and other related process activities, what
are the industry thoughts on using the same equipment for both lead free and
non-lead free?


I appreciate any thoughts and welcome all ideas.


Regards,
Dacia

----- Original Message -----
From: "Blair K. Hogg" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 26, 2004 9:34 PM
Subject: [LF] Mixed Technologies - Solder and Lead Finish


Greetings LF Forum,

I'm confused (again), but that's not unusual.

I seem to remember a thread a while back (checked the archives - found a
post by David Suraski on 5/31/2001) that indicated that use of components
with a lead finish containing lead would harm the reliability of solder
joints of lead free solder. It was my understanding from this that the small
amounts of lead from the lead finish dissolving into the LF solder joint
caused the solder joint to be unreliable. However, more recent posts
indicated otherwise.

I also remember somewhat recently that someone stated that use of lead-free
component lead finishes in a tin-lead process can cause problems, since the
lead-free finishes won't wet as well with tin-lead process parameters (lower
reflow temperatures).

Has anyone had experience mixing lead-free and tin-lead that can comment on
this?

Thanks,

Blair Hogg
QA Manager
GAI-Tronics Corporation

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