New CPU heatsink makes 80% heat breakthrough

A REPORT ON Nikkei Net said that Furukawa Electric has made a copper/aluminium heatsink with remarkable thermal properties.

The heat sink, it claims, will give up to 80 per cent better cooling than conventional sinks.

This design is called crimped fin and the firm expects copper to be at the base of the sink, with aluminium* used for the fins.

And the fins will be inserted into holes in the copper base with a fin pitch of 1.9 millimetres.

The sinks will be manufactured in China and reach a production capacity of two million a month by September next year.

Furukawa has quite a few interesting designs in the heatsink arena that it's patented, either alone or with others.

See, for instance, this page.

And here are some pictures of existing products it manufactures.

An expert tells us: "With heat sinks, aluminum is cheap and light, but copper is better thermally. In Watts per degree C per square centimetre, copper = 4.83 and Aluminium = 3.0

"But copper costs more. Copper is 71 cents per pound Bulk Aluminium is 62 cents US/pound -- a ratio of 1.14. But copper is denser too. in grams per cubic centimetre. Copper = 8.96 and Aluminium = 2.70, this ratio is 3.31.

"That means a certain volume of copper costs 3.8 times as much as the same volume of Aluminium, at current bulk metal prices, An ideal heat sink is all copper with the fins cast on, since any weld or discontinuity interferes with heat flow, best, but this most expensive solution is only used in expensive applications.

"So a compromise is sought. The best hybrid is a copper plate and into that plate you make fine slots about 1/2MM wide into which you insert Aluminium fins(ideally they are dovetailed at the bottom and tapered in cross section towards the extremity, but that costs extra in making them and the solution here is low cost driven.

"You can also insert aluminium pins that are round and densely packed on 2-3 mm centers. Once they are inserted, you need to crimp them under copper/aluminium flow conditions so that the tiny gap between the copper and the fins is squeezed out of existence and you have what they call a 'gas tight joint' The copper and aluminium are in effect welded together for maximum thermal conduction across the joint. This takes great pressure and careful design as you need to make both metals undergo plastic flow so that all air pockets are squeezed out of existence.

"The final step would be to machine the copper bottom into an optical flat that is as flat as the exposed silicon die it will mate with. That means the minimum of heat paste is needed (ideally a silver bearing paste) then you make silver pastes. They can be made all the way up to about 97% silver by weight, and this is a very thick electrically conducting paste since all the psrticles are touching each other. It also makes the best thermal paste if you can tolerate the lack of insulation.

"You then make some provision for fan mounting and you also need to filter the dust from the system to minimize dust accumulation on the fins. This is usually done with a filtered air input port to the box that makes the box a pressurised box, and that means no dust may enter except through the air filter, so the hest sink draws dust free air and does not block up."

But, he adds, dust is a real enemy, perhaps the real enemy. µ

* ALUMINIUM IN THE UK, Aluminum in the USA. See The INQUIRER guide to English English