Well I think I can comment.
The NPL report which is available from the NPL web site on Lead Free
Reliability with Mixed Alloy Rework concludes that there were few issues. I
have said the team should, in my opinion, have included reliability testing
of rework joints as another reference. I currently work with the NPL team,
but Chris Hunt may like to discuss the issue further on the forum.
The comment on inspection I don't see it to be a major issue, the basic
criteria for inspection should remain the same in the IPC documents for
lead-free but there should be reference joints of the different alloys to
give a reference to inspectors. The volume of solder, height up the leads,
allow areas of the pad not to be covered etc for level 3. This is currently
what I do for training sessions and also do on the NPL Masterclasses.
I believe the bigger issue will be when we debate the issue of including
fillet lifting and pad lifting as a process indicator and not a defect!
Results from different lead-free studies have not seen this to be a
reliability concern, but then there are still people reworking pin hole and
blow holes!
Thanks for the comment from the SMART Group Experience text from the SMART
Group web site, its nice that some one reads it. I would have finished the
rest of the results but other company's volunteered to the do the sections
and the push off force measurements and I have still to receive them.
Bob Willis
2 Fourth Ave, Chelmsford, Essex, CM1 4HA
Tel: 01245 351502
Fax: 01245 496123
Mobile: 07860 775858
Email: [log in to unmask]
Web: www.leadfreesoldering.com
Web: www.bobwillis.co.uk
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of No Name
Sent: 19 August 2003 14:23
To: [log in to unmask]
Subject: Re: [LF] PCB finishing type for lead free solution with CSP,
BGA & press-fit connector
Hi UK-Bob and IPC-LF Listservers,
Bob, This story was well done and very consistent with what I have
learned from multiple recent sources and know from experience.
I hope that you will update us on the link for the final report
when it is available.
On Page:11 (if you print this out in Landscape mode) under SM
ReWork & Repair I would disagree that we could or should willy
nilly mix alloys. This maybe is OK in a lab or experiment room
yet is bad business and endangered engineering in manufacturing.
Under Visual Inspection on the same page the problems many are
going to have in manufacturing are overly minimized. I have built
my own sample visual inspection kits for visual processes, one
quite recently, and although a lot of fun due to humans, take
quite a bit of engineering effort to create continual consistency.
(Oops notice I like alliterations, a sign of age)
Again Thanks, Well Done.
YiEngr, MA/NY DDave
>Following the comment from Peter we used solder levelled boards on the
>Lead Free Experience I was running six weeks back in Brighton the
>process, equipment, finishes and components we were running at
>outlined in the story.
>http://www.smartgroup.org/ev_leadfree3.asp
>
>It was great fun with 150 engineers all playing with lead-free.
>We are just waiting for the sections and push off results before
>we post the full results from the test boards run at the Experience.
>
>Bob Willis
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