Jim,
I would have to agree with Ed. Pre-tinning should help immensly, just be
careful of leaching, although it shouldn't be a concern unless you plan on
recycling LCC's off reject boards.
Bruce Misner
> ----------
> From: Edward J. Valentine[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;Edward J. Valentine
> Sent: Thursday, March 30, 2000 11:09 AM
> To: [log in to unmask]
> Subject: Re: [TN] SMT DEFECT RATES (DPMO)
>
> Jim - A side question - Are you pretinning your LCC's? If not, you should
> seriously consider the pre-tinning operation, especially if the Gold
> castellations are contaminated. You would know this ahead of time by
> verifying the coverage after pre-tinning. And, in my experience, the
> pretinning produced significantly better soldering results even though you
> are adding additional process steps. Ed/
>
> Ed Valentine
> Electronics Manufacturing Solutions
> 8612 Mourning Dove Road, Raleigh, NC 27615
> Phone: (919) 270-5145, Fax: (919) 847-9971
> Email: [log in to unmask]
> Website: http://www.ems-consulting.com
>
> ----- Original Message -----
> From: Marsico, James <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, March 30, 2000 10:29 AM
> Subject: [TN] SMT DEFECT RATES (DPMO)
>
>
> > Dear Technet:
> >
> > I've been tasked by my superiors to query industry to find out what
> other
> > electronic assemblers are yielding off of their surface mount line. To
> > compare apples to apples, here are my specifics:
> >
> > We assemble SMT for military/high rel. The majority of the parts are
> > ceramic leadless chip carriers (LCCs) and ceramic chip components
> > (resistors, caps, diodes). We're starting to track solder defects more
> > closely when the assemblies come right off the line, and we don't like
> what
> > we see. The major anomaly is insufficient solder fillet on the LCCs.
> > (There could be one joint insufficient out of 20. By the way, solder
> paste
> > deposits are perfect!) Whether or not these are actually defects is
> under
> > discussion.
> >
> > What I'd like to know is:
> > 1) What kind of defect rates (PPM) are others, building similar
> > assemblies, getting from their SMT lines.
> > 2) Does anyone experience insufficient solder on LCCs?
> >
> > Thanks,
> > Jim M.
> > AIL Systems Inc.
> > 631-595-5879
> >
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