RE: SMD soldering (off topic)

Superglue? Jeez!

I have a stereo microscope ($350 at Edmund) and a fine-tipped iron - and
a flux pen.

What I do is flow some solder on one pad, position the device and solder
down one leg. Once one leg is secure, I solder down an opposite corner
leg. Now the part will not go anywhere and I can solder the other pins
easily.

If the bare board has an excess of solder on it, sometimes I can just
use a flux pen across all the pads and hit each pin of the device
allowing the solder already on the PC board to reflow. Often times, for
small pitch parts, that is enough.

For resistors and caps (two-lead devices) I put solder on one pad, and
then slide the part into it, while reflowing the solder, using tweezers.
Once one end of the part is down, the other end is easy.

I would shy away from superglue. For one thing, it will flow everywhere
and get out of control. For another, you won't be able to change the
part if you need to!

Another trick: When you need to change out a failed SMD part like a CPU
chip, use a sharp Xacto knife like a micro-saw to cut all the legs off
the part and take out the body of the part. When all the legs are
separated from the device, it is easy to heat them and slide them off
the pads with minimal damage to the pads. Clean up using flux remover
spray and then re-flux the board well before you put a new part down.
This technique saves the pads from excess heat and stress. Saw the legs
off gently and slowly.

Chris

By the way: I have six new 72-Pin TINIs (1 Meg) to sell now at $60 each
to anyone who needs them. Please write me off-list if you are
interested.



-----Original Message-----
From: tini-admin-6tN4nzCoH/[email protected] [mailto:[email protected]] On Behalf
Of Tom Blough
Sent: Monday, January 19, 2004 9:27 AM
To: tini-6tN4nzCoH/[email protected]
Subject: [TINI]SMD soldering (off topic)


I know some of you out there are hardware guys and were wondering if
anyone had any pointers on hand soldering surface mount devices.  I'm
going to make a few boards to play with some of the 1-wire devices and
have never done SMDs before.

I'm thinking of supergluing (any problems with the superglue electrical
wise?) the chip down, fluxing the leads, and then heating and applying
solder to the pads (0.015 tip and solder).

Will this work?  Any other methods for hand soldering?

TIA,

Tom Blough
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