On 4/25/08, Jesse Lackey <jsl-ml@celestialaudio.com> wrote:
> Hi - I've done a bunch, hand soldered with wire solder, no problems.
> I suggest using a flux pen like Kester #186.  I soldered them the same
> way as tqfp: use flux pen on pcb pads, tack the chip down on corners,
> put more flux down, then solder "pins" by just sweeping solder across
> them.  Fix any bridges with solder braid.
>
> They actually go faster than tqfp, since the solder "sweep" is really
> quick once you get the hang of it.
>
> Also - sometimes the QFN bottom pad must be connected to ground,
> sometimes optional, but it is there for mechanical strength.  I put a
> 50mil via in the pad so I can solder it down from the backside with fine
> tip soldering iron.
>

Interesting, your idea is exactly the same as Leon Heller in this
Microchip forum thread.
http://forum.microchip.com/tm.aspx?m=327590

I am not a real hobbyist since I do not build board at home
(normally I will buy the demo boards instead) and I have
not designed any boards. But occassionally I need to do
rework on the QFN parts. The problem seems that I do not
have a steady enough hand.

There is also stability issues. I have done several rework
boards this time (QFN 6 with two center pads, but there is no
via since this is meant for reflow and not manual rework) and
some of them do not work well after a while. I use flux pen
as well and I use Hakko 850 hot air station and Hakko 936
soldering station as well as Hakko Solder Wick.


Xiaofan
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