ROHS I believe.  Although we do have a waiver to use leaded solder.

Regards,

Jim

> -------- Original Message --------
> Subject: Re: [EE]: SMD soldering question
> From: "Bob Blick" <bobblick@ftml.net>
> Date: Thu, May 19, 2011 11:25 am
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
>=20
>=20
> On Thu, 19 May 2011 07:39 -0700, jim wrote:
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> >  Where I work, we have some PCB's that have been populated by a contrac=
t
> > manufacturer. Actually some were
> >  populated by one CM and others were populated by a different CM.  But
> > the phenomenon has been seen on all
> >  boards, so it isn't just one CM's process that is causing the problem.=
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> > We have checked with the CM's about
> >  their process, and Samtec approved of both of the solder reflow
> > profiles as well as the solder paste
> >  application process.Anyway, each of the boards use a surface mount
> > connector from Samtec.  When these=20
> >  boards go through our production testing, which includes several cycle=
s
> > of hot (85C) and cold (-40C)=20
> >  temperatures, we find that the solder bond between the PCB pad and the
> > connector pin fails, which in turn
> >  causes the unit under test to fail.
>=20
> Is this lead or ROHS solder paste?
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> Bob
>=20
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>=20
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