On Wed, 01 Feb 2006 12:43:26 +0100, Vasile Surducan <
vasile@...-cj.ro>
wrote:
> I'm curious if someone has success in reflow tehnique for soldering
>
> these parts using homebrew technology.
>
> Mostly are parts used for microwave, with thermal pad and no pins
>
> (pins metalised on ceramical package).
>
> Hand soldering is excluse.
>
>
> thank you,
>
> Vasile
>
yes, it works, i have reflow soldered TQFN.
Just smear some paste all across the footprint, place component, and hit
with hot air or a oven.
Excess solder will squeeze out and bead up on the outside of the
component, sometimes causing shorts, then it must be removed (e.g. solder
wick). But if you spread it evenly this won't happen.
The problem is routing all the signals, and especially thermal connection
to the pad if you want to do homebrew boards with no vias as such.
Making the pads slightly longer so that they stick out a bit makes
inspection easier. Also, route straight out from the pins not sideways at
the outer ones, that will harm self-centering. Where you connect pins to
the thermal pad, elongate the pad straigt in same with, not a wedge or
something.
I wasn't sure if it is viable to solder these at home, but surprisingly it
was no problem. You may not see the pins once mounted, but there can't be
solder bridges like with individual pins, if the component sits flush on
the PCB there is just no space for them.
I have only soldered two TQFNs (one 24 pin and one 32 i think, both 0.5mm
spacing) but both worked without a hitch.
ST