Dave you touched on a point that has always seemed silly, I know it will not
change but there should be on soldering standard having different classes
always seemed strange to me when meeting level 3 is easy.
I have said on many occasions that in the case of lead-free the criteria in
610 should remain the same but only reference joints should be included.
PS What ever happened to the boards you were sending me!!!!
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 Dave Hillman
Sent: 16 February 2004 14:19
To: [log in to unmask]
Subject: Re: [LF] : technical question: annealing time and temperature
Hi Keith! Yep, you bring up a very critical idea that the IPC committees
have pushed - a solder joint is a solder joint and the use environment is
the determining factor for solder joint reliability provided simple basics
(e.g. good wetting, good geometry, good microstructure) achieved. The
example I like to use, especially during a factory tour or an audit when
someone suggests/questions whether we are making Class 2 or Class 3 solder
joints, is that the wave solder machine does not have a choice switch for
Class 2 or Class 3 solder joints! As you stated, we all work to create a
quality solder joint and the service environment of the electronics
equipment is the final discriminator. I just need more time than July 1
2006 to understand how the Pbfree solder joints I produce interact with my
use environments - particularly the life critical applications.
Dave
[log in to unmask]
Sent by: Leadfree To: [log in to unmask]
<[log in to unmask] cc:
> Subject: Re: [LF] :
technical question: annealing time and temperature
02/15/2004 04:37
PM
Please respond to
"(Leadfree
Electronics
Assembly Forum)";
Please respond to
KSweatman
Dave,
You are right that there is a difference between general and consumer
electronics and "high performance" electronics. That does not mean,
however, that
experience gained in general and consumer electronics is totally irrelevant
to
high performance electronics. A solder joint does not "know" whether it
is
in a walkman or a jet fighter. All it "knows" is the mechanically and
thermally induced stresses and strains to which it is subject and there can
be some
overlap in that range of "experience". In fact given the intrinsic
weakness
of tin-lead solder part of the design of joints for high performance
electronics has been to try to ensure (e.g. by building in stress relief
and reducing
thermal mismatch) that the solder joints are not subject to stresses and
strains
that are too much more extreme than those experienced by a soldered joint
in
a walkman. The rapidly accumulating experience in consumer and general
electronics can provide a foundation on which high performance electronics
can
build. As I have mentioned previously that is how confidence in tin-lead
solder was developed.
Keith Sweatman
Nihon Superior Co., Ltd
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