Posted by Exidor on 2, 2001 at 1:17 PM:
In Reply to: Tips on making stronger solder joints? posted by Matthew C. Waterman on 30, 2001 at 12:12 PM:
For a strong joint, the solder must 'wet' the copper. If you just had a ball of solder sitting on top of the copper, that is not a good connect (a 'cold' or 'dry' joint). It may be due to the copper not getting hot enough to melt solder. To help ensure this try the following: Clean the soldering iron by wiping on a damp sponge. Add a little bit of fresh solder to the end of the iron. This gives a bigger surface for the iron to pass heat to the things being soldered. (A dry iron may only be touching at a single point. A little solder on it bridges the gaps.)
Hmm ... there probably is a good tutorial on soldering somewhere on the web, but I didn't find anything good right off.
So, yes, as others have suggested, make sure the copper is clean. Pencil eraser, wipe with rubbing alcohal, depending on the surface, I'll sometimes do a little light scraping with a knife.
Tin the of the wire - heat it with the iron and apply a little solder to coat it.
You might also try tinning the copper that you want to attach the wire to. This may be harder to do as it is harder to get a portion of a circuit board up to the solder melting temperature. The traces on the board, and the board itself will be carrying heat away from the copper that you want to solder to. Don't apply an iron for too long, or the copper will delaminate from the board.
With the wire and possibly copper pre-tinned, hold them together, put the tip of the iron down where it will touch both of them and hold for a couple to a few seconds, then touch the solder down to the junction of the wire and copper on the other side. The solder should melt from the heat of the parts, not because it is touching the iron. (And yes, by this point, you would really like to have three hands to be holding all of these things.) Add enough solder to coat the copper and wire and form a little fillet between them. Remove the iron and let the joint cool for a few seconds before letting go of the wire. If the wire is allowed to move while the solder is cooling and partially molten that also will not be as good of a joint.
I hope that helps a little, and be sure to wash your hands after soldering before eating. Lead does not make for good nutrition.
-><- Exidor