AVR-Chat

> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] solder paste vs solder wire
>
> Hi there,
>
> I wonder if solder paste is easier for soldering
> atmega128 on a board. I tried solder wire and the result is not too
> good and bridges formed frequently. It could be that I am using wire
> that is too thick. And my inexperience on soldering SMT parts
> definitely did not help at all. :)
>
> If solder paste will do wonders, any recommended brand. I can use just
> regular iron with it, right?
> No hot air blower required?
>
> thanks
> thomas

The tricky thing is solder flux.
Solder Paste (oven or hot air blower solder) has lots of flux, and that does
the trick.
Flux doesn't allow bridges to build up, except if there is excess of solder.
Flux pulls strongly solder just over the metal part of the exposed circuit
board track or solder pad.
Flux acts as a strong connection between metals and pulls all fluid solder
to stick together, *along* with the solder pad, so no solder bridges will
appear.

Buy some solder flux and apply generously over the solder pads with a very
small brush, be generous, don't be afraid, you can wash and clean the board
later with alcohol.  Position the SMD part exactly over the pads, use a
scotch tape to hold it in place.  Use a thin solder wire to hold just the
corner leads, remove the scotch tape, spread at easy the solder wire with
the iron all over the pins, not too much. The flux will be responsible to
make the solder to stick *only* to the leads and pads, not forming bridges.

If bridges form, apply more solder flux and use a solder wick to remove the
excess.
Whenever working with tinny solder, flux is *always* the answer. Trust me.

Wagner

ps:  for some smd soldering tips, check my webpage:
http://www.ustr.net/smt/