Welding heatsinks

[globalweb]

Hi guys

Is it possible to weld heatsink together and still have fully functional thermal dispation? I’m using these heatsinks

http://cgi.ebay.com/HEATSINK-ALUMINU...QQcmdZViewItem

[Stocker]

It may be possible to weld the aluminum but you would have to do something pretty exotic to maintain thermal charicteristics across the weld. I think.

[jacco vermeulen]

The quality of aluminium welding has very much improved.

For good strength the melted mother material has to be thoroughly mixed with the weld, a strong weld also has good thermal crossing. That leaves the welding material that has to be homogenous.
The aluminium parts i welded 30 years ago with argon-arc had joints that looked like spongecake.
MIG and TIG welding have been so much improved that an aluminium weld can be stronger than steel welds nowadays.
Thermal transfer of welded aluminium can be good, depends mostly on the skill of the one doing the TIG welding.
The TIG welding on my boat was done by a photo-welder, i could never weld like that.

You can google for an article called: Why Aluminium ?
(originally by D.Boon of Vripack yacht design for Palmer&Johnson Yachts/Wisconsin)

[globalweb]

Is it better to use a aluminium plate (1-3mm) mounted on the backside?

[AMV8]

Hi

I am also considering welding some small heatsinls together.

I have used chemical metal on other alloy items and it has worked. I am planning to try chemical metal om some heatsinks and I am hopeful.

On some others with machined faces I am planning to use acrylic glue as used in the aero industry - although I think this will only work to fasten two machined faces together.#

Don

[jleaman]

What are you building ? why not use copper bar ? I use these heat sinks from russ and they work really well with all my class a amp's.

Jase

[globalweb]

I’m building an Aleph-X 100W . Using this scematic: http://www.kk-pcb.com/alephx.html
I have four heatsinks per channel-2 power transistors/heatsink. After about one hour they will get to hot, over 60 C. If I use one more heatsinks/channel I think it’s going to be enough. But the problem with this is how to spread the heat between the heatsinks. I tried to mount them side by side VERY tight but that wasn’t nearly enough. So what’s left? All can think of is:
Either welding them together or mounting them with think aluminium plates.

[globalweb]

Copper bar is a very interesting idea. Im not sur how expensive it is though. Also how much do you need and whats the best design?

[jleaman]

Copper bar should not be that expencive.. Do you have a picture or diagram with mesurements of the heat sink's you have or want to use ?

Jase

[Zen Mod]

Originally posted by jacco vermeulen
The quality of aluminium welding has very much improved.

For good strength the melted mother material has to be thoroughly mixed with the weld, a strong weld also has good thermal crossing. That leaves the welding material that has to be homogenous.
The aluminium parts i welded 30 years ago with argon-arc had joints that looked like spongecake.
MIG and TIG welding have been so much improved that an aluminium weld can be stronger than steel welds nowadays.
Thermal transfer of welded aluminium can be good, depends mostly on the skill of the one doing the TIG welding.
The TIG welding on my boat was done by a photo-welder, i could never weld like that.

You can google for an article called: Why Aluminium ?
(originally by D.Boon of Vripack yacht design for Palmer&Johnson Yachts/Wisconsin)

hehe-speaking of welding...
yacco-can you point me on some handy webb source...friend of mine need new paddle for entirely new setup (new engine+Z-foot) for his 6m boat ; problem is that almost entire boat is DIY made,and few local guys asks too much cash for calculations........
so-in short-how to calculate paddle parameters-.......?
sorry for off topic

btw-copper spreader is way to go