Best way to solder thin copper heat fins to soft copper pipe for radiator/heat exchanger with small butane blow torch?

Trying to attach 36cm (14") x 5cm(2") x 0.125mm(0.005") thick electrolytic copper heat-fins to 20 hollow soft copper tubes 6mm outer diameter, 0.4mm thick walled copper pipes. Would ideally like to use silver based solder rather than tin-based. Is it realistic to use high-silver-content solder on such thin copper, and with a small butane blowtorch (has to be small as fins only 1cm apart)? Can I use silver solder or do I need to use tin solder? Any help/suggestions welcome!

Use a heat gun. it can certainly get to the solder temperature and will not melt or damage the fins.
jtobako8 years ago
A pic of how this goes together would help. That length of pipe is going to be hard on the small torch, but it depends on your skill with the flame and what temp of silver solder you are looking at using. Tin solder is going to be much easier, but I have a feeling that you are still going to melt some of the heat-fins.