Some of the big guns are away and have not been
heard from.What do you think about this 0402 chip problem Moonman?
        Regards,
        Ramon

> -----Original Message-----
> From: Steve Gregory [SMTP:[log in to unmask]]
> Sent: Monday, January 12, 2004 3:23 PM
> To:   [log in to unmask]
> Subject:      Re: [TN] reflowing 0402 SMT capacitors with underside
terminations
>
> Hi Tom!
>
> There's a few articles out there that talk about "Phased Reflow
Soldering".
> Here's a link to one:
>
> http://www.reed-electronics.com/semiconductor/index.asp?layout=article&
> articleid=CA274087&industryid=3026
>
> Something I've done in the past that works really well in my opinion, is
to
> use a 2%
> silver solder paste. Sn62/Pb36/Ag2...works in the same way that Phased
Reflow
> does.
> The difference is pretty dramatic when it comes to eliminating tombstones!
>
> -Steve Gregory-
>
>
> > Greetings All,
> >
> > I am having my first experience working with an assembly design that
> > involves 0402 capacitors with underside solderable terminations (vice
> > wrap-around end terminations)... The reflow process seems to cause the
> > components to tilt and skew to highly unacceptable levels. Physically it
> > looks as if the caps floated to the top of the molten solder volume (as
if
> > on pontoons) then slid down one way or the other. The vendor made a few
> > recommendations including migration to a thinner (4 mil) stencil as well
as
> > some pad design and nitrogen tweaks and... Even after implementing these
> > recommendations we are experiencing the same problems, just to a
slightly
> > lesser (although still unacceptable) degree... Does anyone out there
have
> > any additional thoughts on how to remedy this sort of issue?
> >
> > We do build another part [successfully] with a similar style component,
but
> > it is a 1206 form factor and is perhaps massive enough to keep from
floating
> > up the way the 0402 caps do...
> >
> > Your collective wisdom is greatly appreciated!
> >
> > Best Regards,
> >
> > Tom Ochenas
> > Process Engineering
> > Maxtek Components Corporation
> > 2905 SW Hocken Avenue
> > Beaverton, OR 97005
> > [log in to unmask]
> > desk: 503-627-3078
> > fax:  503-627-4651
> >
>
>
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