> The chips wiggle themselves into place during reflow. Not only is
> self-centering one of the benefits of solder paste, there is little
> you can do to prevent it.
At least two things prevent it actually;
1. Pads not designed for reflow
2. No solder mask
Again, your idea of self centering may be different from mine. All
boils down to taste and expectations.
--- In
Homebrew_PCBs@yahoogroups.com, "Mike Young" <mikewhy@s...>
wrote:
>
> Solder mask has absolutely no effect there. Aside from BGA, the
entire
> footprint including the pads and spaces is not masked.
>
> It's one of those things you'll have to take on faith until you see
it for
> yourself. The chips wiggle themselves into place during reflow. Not
only is
> self-centering one of the benefits of solder paste, there is little
you can
> do to prevent it.
>
> There's nothing magic about paste. You don't even need paste and an
oven to
> prove it to yourself. Point a heat gun at a hand soldered 0402 or
SOIC and
> see.
>
> ----- Original Message -----
> From: "derekhawkins" <eldata@m...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Tuesday, January 31, 2006 2:11 PM
> Subject: [Homebrew_PCBs] Re: Question: using surface mount
resistors/caps ?
>
>
> >> Why would you think you need soldermask?
> >
> > Exposed tracks leading to the pads will cause unpredictable
imbalances
> > as the solder "wicks" away on them. Self centering is not one of
the
> > benefits of solder paste in the absence of solder mask.
> >
> > --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
> > <stefan_trethan@g...> wrote:
> >>
> >> Most of us, actually, i guess ;-)
> >>
> >> Of those that using smd paste that is.
> >>
> >> Why would you think you need soldermask?
>