[time-nuts] OT: RoHS crap

[Michael Sokolov]

Hello again,

Thanks to everyone who has replied to my query!

I have a few additional questions though:

1. What about the tin whiskers?  Will they be eliminated by using SnPb
solder, or will they always remain a potential problem when one is
forced to use a Pb-free part?

2. Several people have replied that I can use the traditional SnPb
soldering process just fine.  What about the temperature?  If I set the
soldering iron or the reflow oven to the standard SnPb temperature and
it never gets to the higher Pb-free soldering temperature, what will
happen?

> It is fun to watch the RoHS parts as they reach soldering temperature.
> the shiny finish turns to a mossy crinkle finish, like a wrinkle finish
> paint job.  What you are seeing is the electroplated finish crystalize.

That's what I was referring to above -- if I use the standard (lower
temperature) SnPb process, the above will never happen, right?  What
would be the consequences?

> The big problem with RoHS parts is they don't age well on the shelf.
> I have found that over time, they will not take solder as quickly as
> when they are new.  So, new old stock (NOS) RoHS parts will be a much
> bigger gamble than NOS tin/lead parts.

Well, that is not an issue -- I would only use RoHS parts when forced to
use modern crap because the good old stuff is no longer available, so it
would be fresh from Digi-Key.

> 1) Test & MEasurement electronics are exempt at least  until 2009, maybe 
> until 2011 or longer. Good for us, we can keep using the good  old Pb.

But the problem is that many standard parts (like general purpose
microprocessors) are now only available Pb-free.  So what good does it
do if we are allowed to have lead if your design needs a microprocessor
and the one you want to use is only available Pb-free?

That's the problem I'm facing -- it's virtually impossible to get
traditional leaded parts any more, at least from Digi-Key.

> But I know for a fact that some RoHS BGA chips (surface mount Ball Grid =
> Array) will not be correctly mounted with a standard Pb process; the reason=
> is that the ball under the BGA package need to melt and fusion with the so=
> lder deposit, and that can only happen at RoHS temperature (higher than sta=
> ndard Pb process).

That's good to know.  I stay away from BGAs whenever I can of course,
but some chips that I may want to play with some day (PowerPC processors
for example) are only available in BGA packages.

MS