Warning To All Using Ax478 Heatsinks
 

Ok...... i was getting bad temps with my thermalright Ax478 and any fan..... so i just stoped using the computer for a while...... and today..... i look at my window..... and i see the fins and fan of my heatsink resting onto of my GF4..... i think humm...... look at the cpu........ look- theres the copper base plate.... AWW ****! It broke off from the Copper plate!!! Thankfully i wasnt using it..... but this thing did nothing but run a 2.26 at stock for less then 2 days!! WTF??

Heres some pics.....
http://www.theforumisdown.com/upload...sHitz_0002.jpg

very scary - I can only hope it was a one off mistake. Better get the rma underway....

I have been using a lot of AX-7s with great results. I have often wondered how Thermalright bonds the aluminum body to the copper base? I assume it is a thermal epoxy (sorta like AS epoxy?). I don't know of any solder/flux combo for Cu-AL???

Does anyone know for sure how Thermalright bonds the Al to Cu??? Thanks,

RoboTech

They solder aluminium fins to copper base, simple :)

The Spyder, god damn what kinda luck you have :D First time I hear about anybody messing with their AX-serie coolers. I have a AX-7 and now I'm using SLK-800, both damn great coolers.

This appears to be a very bad design.

Due to the difference in the coefficients of thermal expansion for copper and aluminum. Repeated thermal cycling of the heatsink will rip the solder joint apart.

The coefficients of thermal expansion are:

Copper - 17ppm/K

Aluminum - 25ppm/K

Some more info here.

can copper be fused to al?

In order to solder Al to Copper you need a transition metal, like a steel.

Someone told me recently that the aluminum body on the AX-7 is tin plated, which allows it to be soldered to the copper base. That sounds plausible... ??? and I've noticed the AX-7s do look like they have some sort of plating.

Anyone else heard this?

you cant solder exposed (not plated with anything) aluminium to anything!,
this would explain it, but if it was soldered it wouldn't/shouldn't come apart,

Then how did I pull this off? Copper fitting to AL top.
http://www.customcooledpc.com/aluminumWB4/006.JPG
Must have been extream luck? :confused:

WT*, how did you pull that off?
i got my info from someones thats been welding/working with metal for over 30 years, and as far as they know, you cant solder alu, i'll show them that pick and see what they have to say about it.

i did find this link though on soldering alu http://www.ganoksin.com/orchid/archi...8/msg00348.htm

It's not impossible to solder aluminium, but it is difficult: First, it melts extremely easily, and as the link states, form an oxide. Much practice required.

k, asked my dad again about alu,
apperantly you can weld alu only to alu using MIG and TIG, but you cant weld other metals to it unless its plated.

as for soldering, its like the link says "there HAVE been several solder formulations developed for aluminum, each with it's own specific type of flux". but I doubt that these are available at your local hardware store,

I have been a certified stick and wire feed welder for 7 years now. Been in fabrication and erection for 8. Sheet metal and heavy steel. Just in the last few months got transfered to the boss's other company to run the engraving shop. I have soldered AL to AL with just flux and solder from Home Depot. It is a royal pain but if you have patients and hit the heat levels at the right moment it can work but rarely done. It is just to much a pain in the ass.

Also in reference to the pic I posted, if you can get the solder to actually stick to the al your set. I did that and then solder a little onto the copper fitting and heated both peices up to where the solder was liquide and touched them together. It is a bitch to do. it took a couple hours but I was determined. Since swappedthat out for a read barb.