Aluminum vs Copper Heatsink

[bally30]

I want to buy a heatsink but heard copper heatsinks are better heat conductors & dissipate heat better than Aluminum so my question is why do companys make copper & Aluminum heatsinks & not pure copper heatsinks for example they use Aluminum for the fins & copper for base & pipes wouldnt it be better if they made the fins from copper

 

[MWP0004]

You will find that fin and tube heat exchangers rarely use copper fins.

Aluminum is simply cheaper than copper. Also, if I'm thinking correctly, the aluminum will dissipate heat more rapidly than copper will.

 

[timeconsumer]

They do make pure copper heatsinks, like this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16835118223

However even being full copper, it's not that good. The design of the heatsink matters a lot more. And with a lot of heatsinks now being dual tower 160mm 3lb monsters (http://www.newegg.com/Product/Product.aspx?Item=N82E16835608045), doing full copper would be expensive and dangerously heavy.

 

[JackNaylorPE]

There are pure copper heat sinks (CR-95C from No Fan pictured below)

Installed pics here:

http://www.silentpcreview.com/article1349-page3.html

Copper has a much higher heat transfer coefficient than Aluminum and this does come into play significantly in some circumstances. With a small contact area on CPU, copper does a much better job than aluminum. As the surface area gets larger, this oft compensates as the heat transfer rate (how fast it travels) is of less concern. Another example where copper rules is in radiators ... that's why CLC type water coolers have a hard time matching air coolers because copper takes the heat out of the water at a much higher rate then aluminum does.

When we talking stacked fins tho, air flow velocity, large surface area and turbulence dulls the edge that copper has and manufacturer's, having little to gain and much to lose (weight / cost) from copper have just found it not worth their while to 'go there".

 

[Eximo]

Cost and weight are the primary reasons,yes.

You can actually get some really good all copper downdraft coolers. They make amazing replacements for stock coolers in low-profile situations.

Using aluminum does let them get away with more radical designs though, which as timeconsumer says has a greater impact. The lighter aluminum allows for more surface area, but isn't as effective as the same amount of copper would be, but size really does matter, which applies to MWP004's point.

You'll see copper used when space is at a premium and heat needs to be removed. Laptops tend to have a lot more copper in their heatsink than the average desktop.

 

[bally30]

MWP0004 i Thought so too that aluminium dissipates heat better than copper but after a lot of research i think copper conducts & dissipates heat better than aluminium its not conclusive as the subject has been debated a lot & i cant find A definitive answer.

Thank you to timeconsumer & JackNaylorPE as i was trying to find a pure copper heatsink to see its specs & Compare & now i can

 

[Susquehannock]

Aluminum dissipates heat faster AFTER the energy source has stopped. Has to do with density and weight per given joules, among other things. Think of a piece of aluminum foil when you take it out of the oven.

 

[bally30]

You are right Susquehannock considering they use Aluminium to dissipate heat from the RAM & dont use Copper.
I think copper & aluminium combined make the best heatsink, Copper to absorb the heat & Aluminium to dissipate it

LAST QUESTION:
Because Silver adsorbs heat faster than Copper & Aluminium why dont they make heatsinks like for example

Aluminium fins, Copper heat pipes & plate
but instead of using Nickle they plate the copper in silver wouldn't that be a better heatsink?
Perhaps they have tried it but found the difference to be 2c & is not cost effective so they chooses nickle instead for aesthetics reasons Instead of practical reasons

Just a educated guess would like to hear others thoughts

 

[JackNaylorPE]

Copper is superior for blocks and heat plates because they transfer heat faster. I don't agree about the dissipation rate thing as copper foil cools almost instantly too but it has no relevance to this topic as we don't really care what the cooler does with heat coming from a PC that has no heat source. We don't need a cooler when PC is off.

The reason that aluminum is used in air cooler heat sinks is that it is lighter and the large surface area results in no significant advantage as the alum / air heat transfer rate differs little from copper to air.

 

[Susquehannock]

Agreed. We are talking about an active state - when the heat source is on.

With bi-metal sinks you have a loss of transfer between the two materials. Better to have one continuous piece. Solder is even worse. Only a small fraction the thermal conductivity. Think of it as a heat transfer bottleneck.

Silver being expensive would not be cost effective since in the grand scheme of things it's conductivity is only slightly better than copper.

 

[JackNaylorPE]

There are issues with copper too but the goal is not letting it bottleneck the heat transfer stream. We can use bimetal coated copper water blocks on GFX cards because the large surface area provided enough heat transfer that it more than erases the pure copper advantaged.... which is why we see CPU water blocks with a copper face because of the much smaller surface area, we need every bit of surface area to move that heat as fast as possible.