Phil,
Each system/assembly has different service conditions and requirements.
After evaluating three alloys SnCu and two SAC alloys and then examining
solder joints at T0, 1500 0-100C thermal cycles and finally at 3500 thermal
cycles it became clear that initial cracks in solder joints do propagate
and conventional wisdom as to the proper SAC wave solder alloy is probably
based on what is cheapest and not what delivers least cracking.

Without delving deeply into service requirements I cannot comment further.

If you want to dive deeper contact me off line.

John Maxwell

At 12:21 PM 5/10/2005, you wrote:
>I'd love an elaboration on "nearly crack free" alloys.  We have not
>chosen an alloy yet and it would be nice to get it right early on.  I
>want to learn from other's mistakes, er - experiments, yah that's it,
>experiments.
>
>Phil
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of John Maxwell
>Sent: Tuesday, May 10, 2005 1:41 PM
>To: [log in to unmask]
>Subject: Re: [TN] Lead-Free solder for wave solder machine
>
>Kaye,
>It all depends on the size of leads and how many cracked solder joints
>you
>can stand. There are commercially available alloys that are nearly crack
>free and others that have lots that do indeed propagate during thermal
>cycling.
>
>John Maxwell

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