Have not seen the problem you describe.

You're probably forming a solder alloy with your paste and the 85 Sn/15 Pb
on your Altera leads that has a different [most likely higher] liquidus
temperature than you expect or that is defined by your paste supplier's
recommended profile.

Run a profile on the Altera leads that are not soldering.  Probably should
get to 240°C

Look here for solder materials properties
http://www.technicalmaterials.com/metal_prop/soldera.html

Dave Fish

----- Original Message -----
From: "Jorge Rodriguez" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, November 27, 2001 2:17 PM
Subject: [TN] Need Help with 85-15 Altera QFPs


> > Fellow Technetters:
> >
> >       I am sending this looking for any help, I guess I've done
everything
> > as far as the process and I haven't been able to resolve the issue.
We've
> > been having soldering problems for a while with QFPs with 85 Sn/15 Pb
> > finish on the leads. The solder doesn't flow properly and an acceptable
> > solder joint is not formed, the leads can be sometimes lifted with no
> > effort. The solder paste was checked after the screen printer operation
> > and it looked alright, the oven profile was also verified and it's
always
> > within the solder paste manufacturer's recommendations. This problem
seems
> > to be affecting all the different products with this type of component.
> > These part numbers are manufactured by Altera. Has anybody experienced
> > similar problems with QFPs from this manufacturer?, Does anybody have
> > recommendations as far as the reflow oven profile?. I read somewhere
that
> > this particular alloy has the liquidus temperature at 205 degrees, is
this
> > accurate?
> >
>                 Any help would be really appreciated
>
> > Jorge Rodriguez
> > Process Engineer
> > Varian Electronics Manufacturing
> > E-mail: [log in to unmask]
> >
>
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