On Fri, 12 Sep 2003, Mike Estee wrote:
> I agree, soldering a gnats ass to a pad is kinda annoying, but not
> impossible. You need the right tools, and they're kind of expensive
> right now. You don't know soldering until you've soldered SMT! Where's
> you sense of adventure! ^_^
Reflow soldering of SMT parts is really not that hard. The trick is to
use solder paste and a toaster oven (really!). The only really tedious
part is using a toothpick to apply the paste to each solder pad, then
using tweezers to place the parts. I've done this even with 0.5mm
pin-pitch microcontrollers, and they turn out fine.
On critical designs, I'll ante up and have a paste stencil made--then
you just lay the stencil over the PCB and trowel a thin layer of paste
over the stencil such that all the pads are done in about 10 seconds.
Anyway, just heat a toaster oven to 420F, put the prepared board in and
watch till the solder melts under the pins of the largest IC. Then remove
the board and set it on a cooling rack (takes about 3 minutes in my
toaster oven desigated for flow soldering). After it cools, solder on any
through-hole parts and its ready.
I've seen the paste dispenser and picker-placer robots at work on boards
at a factory I hire from time to time. Those are awesome. ;)
Crow
/∗∗/