Q about bonding Aluminum to Copper

[Cyberdan]

Hello,

I'm currently trying to water-cool an 80A ESC, after identifying what I can vs. what I can't get, I decided to saw off one fin on each side of the original aluminum heat sink, and this would allow me to cradle a copper tube on each side. The obvious dilemma is how can I bond them together (Aluminum heat sing and copper tubing) with a material that will allow the heat to still dissipate and the effect of the cooling returned to the ESC?. Soldering is out of the question as Aluminum cannot be soldered, I tried some Radiator/gas tank epoxy putty based repair, but quickly abandoned the idea when I found the bond to be week and it was crumbling when rolled.
Can I use something like JB weld or just plain old epoxy (Would epoxy keep the cooling effective?)? If you know of any other suggested materials that would do the job, please advise so I can see if we have them here in Canada?

Thanks everyone

[RandyatBBY]

Hello,

I'm currently trying to water-cool an 80A ESC, after identifying what I can vs. what I can't get, I decided to saw off one fin on each side of the original aluminum heat sink, and this would allow me to cradle a copper tube on each side. The obvious dilemma is how can I bond them together (Aluminum heat sing and copper tubing) with a material that will allow the heat to still dissipate and the effect of the cooling returned to the ESC?. Soldering is out of the question as Aluminum cannot be soldered, I tried some Radiator/gas tank epoxy putty based repair, but quickly abandoned the idea when I found the bond to be week and it was crumbling when rolled.
Can I use something like JB weld or just plain old epoxy (Would epoxy keep the cooling effective?)? If you know of any other suggested materials that would do the job, please advise so I can see if we have them here in Canada?

Thanks everyone

I have used JB weld with fair results. There may be a epoxy that transfers heat better in the computer industry.

[CornelP]

Try the epoxy potting compounds, these are usually thermally conductive

[sailr]

JB Weld. Works great. I leave the tubes in contact with the fins and then JB Weld over the TOP to hold them on. I don't put JB between the tubes and the heat sink.

[Rex R]

it is possible to solder Al to Cu using the right solder/flux combo...it is however not something I would reccomend as it smells nasty and leaves a hard to remove residue on your iron. if you want to persue this further cheapbatterypacks does sell the necessary solder and flux.
rex

[Cyberdan]

Thanks all for the great replies, I knew I'll get a lot of help here