[sdiy] RoHS

[Ian Fritz]

At 04:20 PM 1/10/06, clark at andrews.edu wrote:

>    We've been using lead-free parts (IC's mainly) in our production line
>for the last 6 months or more and have had zero problems with
>solder-joints.

Isn't it kind of early to tell?


>Are you sure that their 90% wetability isn't referring
>to the lead-free solder process?  No one can guarantee 100% on that
>score just yet...

But you just said you had no problems.  Less than 100% wettability isn't a 
problem?  I've soldered some lead-free resistors with regular solder, and 
it is definitely more difficult to get these to wet.


>    As I understand it, lead-free parts generally have a pure-tin finish
>which poses no problem to traditional leaded (Pb) solder since it's
>part tin anyway.

Not according to the manufacturers that I have looked at.  They call it an 
alloy.


>    This is why you shouldn't use lead-free solder with a part that has a
>lead (Pb) finish.  The lead (Pb) on the surface of the part will mix
>with the tin solder and create a very thin layer of tin/lead (Pb) which
>is much weaker than the bulk of the tin solder surrounding the joint
>leading to fracturing of the joint itself.

Aren't you being inconsistent here?  If you can solder to lead-free with 
lead, then you should be able to do the opposite.


>    Soon, within the next two weeks I'll get first hand experience in
>lead-free production, and I'll be happy to share my results with the
>group at that time (right now I'm in the process of getting lead-free
>PCBs made).

It will be very interesting to hear those results.  It would be nice to 
know more about the metallurgy here, but since no one is saying what their 
lead-free alloys are this may be difficult to winkle out.

   Ian