Hi gearbox! I have soldered a few dozen rebel LED's with good results. Usually I have already epoxyed the rebel to the heatsink before I solder wires to it. Here's my method:
1. scrape the thin enamel-like cover off of the traces on the top side, use the tip of an exacto knife. Dont scrape too hard, but keep scraping lightly until the copper traces look real shiny.
2. Be sure to have a wet sponge or paper towel to wipe the end of the iron. Any extra solder on the tip will not be helpful. After wiping clean, apply a very small amount of solder to the tip.
3. Put the tip of the iron, with solder just appied, onto one of the rebel copper traces, and immediately add a little more solder as close as possible to the junction of the iron and the copper trace. Remove the iron. The copper trace should now have a small amount of solder on it. This is called 'pre-tinning' the trace.
4. Use a small gauge wire. I use 28 gauge for short runs, and 24 gauge for runs up to 60'. Larger gauge wire is bad because it can rip the trace right off of the LED if you bend the wire too much. Smaller gauge wires will not stress the solder connection. Pre-tin the wire end by applying a small amount of solder to it.
5. Carefully clean the end of the iron again, and apply a small amount of solder to the tip. Put the pre-tinned wire lead on the rebel's copper trace, and apply the iron. No need to add solder at this point, just melt what you have already applied.
Here's a photo where I used 20 gauge wire from my battery pack to attach to the rebels, and 24 gauge telephone-type wire to connect two LED's in series. The big 20 gauge wires gave my trouble, breaking away from the contact. I had to re-solder them several times until the project was complete.
What are you going to do with your rebel LED?
Jeff O.