Talk:Heat sink

Scope of this article

I just wanted to comment that heat spreading/dissipating devices are by no means limited in application to microelectronics (or, to put it bluntly, PC microprocessors). I would try to improve this article's scope myself, but my focus lies elsewhere right now. This is merely a suggestion for anybody who might decide to improve the article. -- uberpenguin 20:06, 11 March 2006 (UTC)

Yeah, you're absolutely right. In thermodynamics, the term is used to mean somewhere that heat can be transferred to. In engineering, things like engines, power plants, these all have heat sinks, for example a power plant might use a nearby lake as a 'heat sink'. I think the PC microprocessor usage probably came after all this, and is a fairly specific example. Brendanfox 08:02, 13 October 2006 (UTC)

Not only that, but according to a recent paper in Science, an account of which is here, toucans use their bills as heat sinks. Heat sinks in nature seem to be definitely worth going into the article. Lexo (talk) 10:06, 24 July 2009 (UTC)

Very true, sounds like a PC enthusiast has written the whole article, and so many pictures of various CPUs are absolutely redundant. How about pictures of the heatsink on some Audio Power amplifier or a SMPS switching driver transistor?Sub40Hz (talk) 19:55, 20 October 2009 (UTC)

I'll say it again - hopefully someone who knows the topic can do something. I came to this article looking for info on the theories of how heat sinks (colloquial or not) function in general. Heat transfer. This is "how to design a CPU heat exchanger" by and large. Something more about how this concept functions in general would be much appreciated. Jjdon (talk) 20:29, 2 August 2010 (UTC)

Removed pending citation

It is claimed that some brands of thermal grease that are advertised as containing silver or silver oxide actually contain neither, most notably that of CompUSA.{{citeneeded}}

- 81.155.170.206 16:19, 15 March 2006 (UTC)

The most common filler in the thermal greases is aluminum oxide.

171.64.160.33 09:04, 31 March 2006 (UTC)

I nowikied the template so that this talk page does not show up in the articles lacking sources category. -- Kjkolb 18:42, 6 April 2006 (UTC)

Name?

Heatsink or heat sink? -- Frap 11:24, 21 May 2006 (UTC)

It's "heat sink" in my dictionary. --Charles Gaudette 00:37, 8 June 2006 (UTC)

Yes it is 2010 now and I ask again; is it one word "Heatsink" or two "Heat Sink"? I have seen both with manufacturers or in documentation... Are you sure it is just one word? Seems both are used -- Surf 10:20, 03 Sep 2010 (MT) —Preceding unsigned comment added by 67.136.51.98 (talk)

Removed pending citation #2

"Aluminum has the significant advantage that it can be easily formed by extrusion, thus making complex cross-sections possible."

This doesn't ring true with me — copper versus aluminum — they are both very malleable metals. I further asked someone with aerospace materials management experience, and they called it bogus too. If it can be cited to a reliable source, then by all means, put it back in the article. --Charles Gaudette 01:45, 8 June 2006 (UTC)

Not sure whether this was the original authors source, but a source confirming that claim is Groover's Fundamentals of Modern Manufacturing, Third Edition, p419, which says "Aluminum is probably the most ideal metal for extrusion (hot and cold), and many commercial aluminum products are made by this process...", a few pages later on p424 as an example of extrusions ability to form complex cross-sections is a picture of an aluminum heat sink. Brendanfox 23:46, 18 November 2006 (UTC)

I still have a problem with "significant advantage"; for instance extruded copper wire, and the tools and art of the Bronze Age. Does anyone have the ISBN for that book? --Charles Gaudette 01:24, 19 November 2006 (UTC)

The ISBN is 0-471-74485-9 [1]. The book also mentions "copper, magnesium, zinc, tin and their alloys" as typical metals used in extrusion, but it does seem to draw attention to aluminum as being "the most ideal". Unfortunately it doesn't give any particular reason for this. We could change the wording, tone it down a bit, but the basis of the claim (i.e. that aluminum extrudes better than copper) appears to be valid. Brendanfox 02:00, 19 November 2006 (UTC)

(First off, understand I am not fighting against you, just trying to work our way to a better "Heat sink" article.) Even if aluminum is easier to extrude, the underlying thrust implies that aluminum heat sinks are a cheaper manufacturing process (I'll give aluminum a raw materials cost lower than copper). Thanks for the ISBN. I'll have to do some research to catch-up to you, ... American Metals Association, hmm... --Charles Gaudette 19:04, 20 November 2006 (UTC)

No probs. You might also be interested in the graph from slide 47 of this: [2] - Brendanfox 04:01, 21 November 2006 (UTC)

Copper vs Aluminum for heat sinks: it is correct that warm copper can be as readily extruded as aluminum, but copper remains malleable (soft) after such extrusion. This is a positive advantage for some applications, but not for the shapes typically used for air-cooled heat-sinks. Al is also appreciably less dense than Cu, and this eases issues with vibration. Cu heat sinks are (typically) formed from sheet-like material, which allows less malleable product to be created.

The heat sinks cited are widely used with CPUs. But heat sinks in the form of flat plates are used with printed circuit boards. These are also called "cold plates" and "thermal planes". Heat spreaders are also closely related to heat sinks.

I suggest that the title be changed to "Heat Sinks and Heat Spreaders".

In addition to to copper and aluminum, other traditional heat sink materials include copper/tungsten, copper molybdenum and copper-Invar-copper.

In recent years, there have been important new heat sink materials, including aluminum particle-reinforced aluminum (Al/SiC), carbon fiber-reinforced aluminum, highly-oriented pyrolytic graphite, natural graphite, and diamond particle-reinforced silicon carbide, among others. The latter has been used in IBM servers. CarlZweben 22:18, 5 March 2007 (UTC) CarlZweben

Two considerations for improving article

First, consider noting that the term "heat sink" is a misnomer and that this expression is not found in heat transfer textbooks. A heat sink is a collection of extended fin surfaces (Hot Air Rises and Heat Sinks, Kordyban). Second, consider distinguishing between bonded fin heat sinks and extruded fins, augmented bonded fin heat sinks, etc.

P.K., August 6, 2007

I'm an old-timer, a retired lifelong electronic tech with a couple of years as an associate editor at Electronic Design magazine, and the term "heat sink" has continually been a very mild irritant; it's borderline slang (embedded update follows), although by very wide usage, I'd say that nearly everybody concerned knows what it means. I was mildly sorry to see the term as an article title; it seems somewhat too close to slang.

Update, 20110907 (Sept.): I read a following comment that rebuts effectively the idea that "heat sink" is a slang term. This would not be an isolated instance, it seems to me, of what might have originally been slang becoming an accepted and well-defined term, although at the moment, I can't think of a good example. Live and learn! Regards, Nikevich (talk) 10:19, 7 September 2011 (UTC) (Now using DHCP, so my numeric IP is subject to change.) (End update)

I never studied thermodynamics, but it seems to me that in formally-defined study of heat transfer, there are heat sources and heat sinks. When concentrating on the transfer of heat, it only distracts to give any details of the nature of the sink, it seems to me. Therefore, in such academic discussions, an heat sink is best considered simply as an abstract entity. (The ultimate heat sink is outer space, I'd say, with the atmosphere and maybe bodies of water as intermediaries.)

My technical life spanned octal-based tubes to VLSICs, and when power transistors came into use, calculations of thermal resistance from junction to case and from case to ambient (typically via an heat sink) were (and, I'm sure still are) commonplace.

The term is catchy, so to speak, which has made it popular, like "baud" or "Watts RMS", a term that is technically incorrect*, despite apparently widespread belief otherwise.

• In dimensional analysis of "Watts RMS", one finds contradictions, iirc. There are definite problems when one attempts rigorous analysis. Quite a few years ago, there was a discussion in the Journal of the Audio Engineering Society about "Watts RMS". It asked, (paraphrased) "If there were such a thing as 'Watts RMS', how would it be defined?". What was interesting is than no two numerical definitions agreed! [Updated : Nikevich (talk) 10:19, 7 September 2011 (UTC)]

Regards, Nikevich (talk) 02:25, 13 October 2009 (UTC)

Heat Sink Color

I have heard that Black Heat Sinks work better that non anodized or painted. Yet, I can't find conclusive evidence either way.

I suspect that there has been a misunderstanding of black bodies being ideal sources of thermal radiation. I think that in reality, the ideal source property describes the lack of environmental interference when making measurements.

The Anodize article does state that anodized aluminum has lower thermal conductivity than plain aluminum. Anodized aluminum would be protected from corrosion, which may be more detrimental.

Does anyone have a source with the answer?

Here is what I have found so far: From http://www.radianheatsinks.com/support/faqs.html

  How does the color of a heat sink impact its thermal performance?
  In natural convection a black or dark colored heatsink will perform 3% to 8% better
  than an aluminum heatsink in its natural silverish color. This is due to the fact
  that dark colors radiate heat more efficiently.
  
  In forced air applications, surface color does not increase a heat sink's performance
  due to the increase in convection. The color would provide cosmetic benefits only.

From http://www.globalwinusa.com/faqs/heatsink/color.html

  Does heatsink color affect heat dissipation?
  
  Black is the best thermal body in terms of being a absorber or emitter. Let's assume
  a vacuum situation, if the surface "A" of a black heatsink is totally covered at T1
  (temperature 1) by another black body at T2 (temperature 2), the black heatsink would
  get the energy reflected from another black body at reflection energy Ad(T14-T24) that
  we call "Stefan-Boltzmann" law of thermal radiation, here refers to Stefan Boltzmann
  Constant, it is 5.6697 x 10-8 W/m2?K4. Therefore if based on above, T1 is the
  temperature obtained from the black heatsink onto CPU, T2 is the ambient temperature
  around CPU. So if T14-T24 is a positive value, we know black is the best heat
  dissipation transistor since there is no thermal source around CPU inside PC case.

From http://www.bcae1.com/heatsink.htm

  Do not paint a heat sink. Most heat sinks are anodized aluminum. Painting a heat sink
  (especially if it's a thick coat of paint) is like putting a blanket on the amplifier.
  If you absolutely must paint the heat sink, use the lightest, thinnest coat of paint possible.

Thanks,

Eet 1024 20:59, 13 November 2007 (UTC)

Black does radiate better than other colors. I remember doing experiments on this in my undergrad degree. However color is not the only concern here. Paint usually is a poor heat conductor (especially household paints, this is why there are special heat sink paints), especially compared to metals, and therefore painting a heat sink using regular paints actually hinder heat dissipation. You enhance radiative dissipation (due to blackbody radiation), but hamper convective dissipation (due to air flow). Using very thin layers of paint means you get the full benefits of having a black color, and minimizes that harm you do to convective dissipation. I hope that clarifies. Headbomb {ταλκ – WP Physics: PotW} 13:37, 10 July 2008 (UTC)

I think the websites are saying other things equal black is better, which of course makes sense since black radiates more (although what matters is being black in the infrared, which is far from the same thing as being visibly black). But if the way you get it to be black is by adding a layer of paint that harms the thermal conductivity, it's not worth it; radiation is usually a very small proportion of heat transfer. The radiationsink website is basically saying that in natural convection heat sinks, radiation is a small (~10%) contribution to heat transfer, whereas in forced-air heat sinks, it's an utterly negligible contribution. --Steve (talk) 16:07, 10 July 2008 (UTC)

I agree with Steve Byrnes. Black in the infrared is good, but not at the cost of an insulating layer of paint. JRSpriggs (talk) 21:43, 14 July 2008 (UTC)

The best thing is to maximize the surface area. If you cannot make it wider, then make it corrugated. JRSpriggs (talk) 18:38, 15 July 2008 (UTC)

Found it: Kirchhoff's law of thermal radiation. It all depends on the application, as stated in the radianheatsinks page above. Will consider adding to the Heat_sink#Performance section. Thanks, Eet 1024 (talk) 05:01, 23 September 2008 (UTC)

Material

Do any heatsink use material other than alluminum and copper? Since Silver, for example, has thermal conductivity greater than copper, some manufacturer might be interest in this material. —Preceding unsigned comment added by 124.120.181.104 (talk) 14:43, 7 August 2008 (UTC) can a heat sink ever be made based on "maxwell's demon"?117.192.197.100 (talk) 17:51, 7 October 2008 (UTC)

Silver would not be used since it is a precious metal. For the same reason that gold is not used. Also, if you are using air, the major thermal resistance is the convection resistance. It is worth more to optimise the air side of the heat sink than to use a very expensive material. For the same reason that copper is used, but only if really necessary. Dtc5341 (talk) 10:17, 20 January 2010 (UTC)

The material aspect of sink performance is really glazed over in very little detail about how material selection affects the properties of the sink. Also, the pricing and historical trending information on material cost (aluminum vs copper) seems too detailed for the scope of this article. A simple, "copper tends to costs #-# times as much as aluminum" with a citation, is probably sufficient. 128.158.1.166 (talk) 17:50, 20 September 2010 (UTC)

Everybody seems to be missing the primary purpose of the heat sink, which is to increase the heat mass of the system and thereby slow down temperature rise time. So the ideal material has a high heat capacity first, and high thermal conductivity second. For metals, these properties are related, for other materials, they are independent. BTW, Aluminum passivates, Copper and Silver do not... Over extended service, Aluminum may be superior. —Preceding unsigned comment added by 131.215.115.31 (talk) 17:46, 5 May 2011 (UTC)

Proposed major revision of article

To whom it may concern,

I am planning a major update of this article (heat sinks) and would like some constructive comments. Bear in mind that everyone has his or her own opinions, etc. Find below the introduction that I am going to use and proposed article outline. The article will be updated in segments.

1 Introduction

The term heat sink is colloquially used to describe two objects: 1. The ambient air, river or sea water, or 2. Finned metal object

This article will focus on the later of the two objects. Examples of heat sinks are the heat exchangers on a refrigerator, air conditioning systems, the radiator (also a heat exchanger) on a car. Heat sinks are also used on, for example, cooling of lasers, electronics and light emitting diodes.

A heat sink does not have a “magical ability to absorb heat like a sponge and send it off to a parallel universe” [1]. To explain how a heat sink works, the heat transfer theory of a heat sink will be discussed first. Discussing the heat transfer theory of a heat sink will also seek to answer the question of: “When is a heat sink not a heat sink?”

The term heat sink is never used in a heat transfer text book [1]. When the text books do mention the objects commonly referred to as heat sinks, they use the term extended surfaces. This also relates the “magical ability” of heat sinks, as mentioned earlier. A detailed theoretical model of a heat sink will be discussed based on theory and heat transfer coefficient correlations from heat transfer text books, and fluid dynamic theory.

2 Basic heat sink heat transfer theory model

3 Methods to determine heat sink thermal performance

3.1 Heat transfer theoretical model

3.2 Experimental data

3.3 Numerical data

4 Design factors which influence the thermal performance of a heat sink

4.1 Material

4.1.1 Fin efficiency

4.1.2 Spreading resistance

4.2 Fin arrangements

4.2.1 Pin fin

4.2.2 Straight fin

4.2.3 Cross cut

4.2.4 Flared

4.3 Fin spacing

4.3.1 Natural convection

4.3.2 Forced convection

4.3.2.1 Ducted

4.3.2.2 Unducted

5 Engineering applications

5.1 Processor/Micro processor cooling

5.1.1 Attachment methods methods

5.1.2 Thermal interface materials

6 References

[1] Kordyban, T., 1998, Hot air rises and heat sinks – Everything you know about cooling electronics is wrong, ASME Press, NY

If there are no comments on my proposed updates, I'm going to update the article tomorrow (26 March 2010 0700 CET) —Preceding unsigned comment added by 83.163.169.225 (talk) 10:12, 25 March 2010 (UTC)

Major revision updated. Comments please. I still want to update the LED section... I know of material, but need to sort out the copyright issues. Dtc5341 (talk) 05:38, 26 March 2010 (UTC)

Support for your view: Copper vs Aluminum: although it is correct that warm copper can be as readily extruded as aluminum, such copper remains malleable (soft) after such extrusion. This is a positive advantage for some applications, but not for the shapes typically used for air-cooled heat-sinks. Al is also appreciably less dense than Cu, and this eases issues with vibration. Cu heat sinks are (typically) formed from sheet-like material, which allows less malleable product to be created. Also, I think the article could be further improved by at least mentioning heat pipes in the main text, rather than consigning them wholly to one of the references. Finally, it could be helpful to provide an empty paragraph entitled "non-electronic applications" or some such - an open invitation to other fields. PhysicistQuery (talk) 13:59, 18 June 2010 (UTC)

M S DIVEKAR (talk) 11:00, 26 August 2015 (UTC) I suggest that Heat Sink could be renamed as Heat Transferring Transducer. Heat is actually sunk into an ambient. Devices used between a heat generating device and the ambient are transducers for effcient heat trasnfer by conduction, convetion or radiation.

Black anodized fins may be effcient in heat transfer by radiation. But anodized aluminum is a bad heat conductor as its thermal conductivity is far inferior to pure aluminum. Hence there is a need for efficient heat transfer from the heat generator to - so calLed heat Sink (in current terminology) by conduction first and later from this to the ambient by - may be black anodized surface".

Today manufacturers are just anodizing the entire surface of aluminum which actualy defeat tHe purpose of effcient heat transfer from the heat generator to the ambient. What is really required is Selective anodizingItalic text". This issue has not been mentioned anywhere. So selective anodizing must be highlighted. Pure aluminum gets oxidized fast when it comes in contact with the oxygen in the atmosphere. However this oxide surface can be easily scrubbed away before attaching it to a heat generator(may be a semicondcutor). An anodized surface is hard and cannot be removed easily and hence may need machining, which may alters the dimensions.

In the absense of proper knowledge - all over the world Heat sinks are being black anodized all over- defeating its very purpose. It is necessary to mention that between the heat gnerator to the ambient one could have many stages of transfer involving heat conduction or convection, then conduction and again radiation. So one needs to look at efficieny at all stages for a total Heat Sinking Solution.

M S DIVEKAR (talk) 11:00, 26 August 2015 (UTC)

I suggest that you read WP:COMMONNAME. Also WP:OR, and even something on the metallurgy of aluminium. Andy Dingley (talk) 12:23, 26 August 2015 (UTC)

M S DIVEKAR (talk) 17:08, 26 August 2015 (UTC) I am making these comments and suggestions based on experimental studies, mathematically verifying data found from Wikipedia itself. I wanted to upload some drawings to explain better. I stand by my suggestions and comments. M S DIVEKAR (talk) 17:08, 26 August 2015 (UTC)

M S DIVEKAR (talk) 06:25, 28 August 2015 (UTC) Here is a link to a drawing to show difference in performance between selective anodization and totallly anodized aluminum heat sinks. https://www.dropbox.com/s/59dkn5c8dh3p9zc/wikiHEAT%20SINK%20%281%29.docx?dl=0. Anyone having a access to loboratory can easily verify this by actual experimentation. M S DIVEKAR (talk) 06:25, 28 August 2015 (UTC)

You seem to think (from your drawing) that anodising represents a change to the properties of bulk aluminium, rather than just a surface layer.

Yes, your basic point (black surface emitters are pointless for a device working by convection rather than radiation) is theoretically correct. However the numbers don't stack up for a quantitative analysis. Although pointless, black anodising heatsinks is not detrimental. The surface layer is too thin for any reduced conductivity in the anodised layer to be a significant issue.

There' also the point that it is not a choice between anodised or pure aluminium. Aluminium is prone to corrosion, so the likelihood is between anodised and randomly corroded aluminium (which is an awful conductor), not between anodised and pure aluminium. Andy Dingley (talk) 08:23, 28 August 2015 (UTC)

M S DIVEKAR (talk) 11:52, 31 August 2015 (UTC)

Black or colorless anodizing improves aesthetics only. From one of wikipedia's references black anodizing has higher radiation property. But unless the heat from a source is transferred by conduction to the bulk, improved radiation alone will not help. Hence my suggestion is for selective anodization, rather than total anodization. In a very specific case that I was working on the temperature droop due to anodization was as high as 47 Deg C against just 2 Deg C without anodization!!!! Measurements did support mathematical calculations for as low as 0.5mm anodization. Even a corroded aluminum surface has far higher conductivity than very hard-anodized (cannot be scrapped away ) surface. This is proven by experimentation. M S DIVEKAR (talk) 11:52, 31 August 2015 (UTC)

The calculations here are very simple, the question is about your underlying assumptions for conductivity values and thicknesses. Please show your example, as that would make the point clearer.

Anodising thickness is about 10 microns, depending on the electrolyte chemistry used. A typical conductivity measured in such circumstances is between $\approx 0.5\cdots 1.5\ {\mathsf {W}}{\mathsf {m}}^{-1}{\mathsf {K}}^{-1}$ This conductivity is admittedly low, it's typically considered as 10-50 times lower than that of the bulk metal.

Your example claims a temperature drop increased by a factor of about 24. Which is comparable to the basic ratio of the bulk conductivity, implying that your aluminium metal has been replaced entirely by anodising. That's not a heatsink, it's a thin foil with about 5W/cm^2 through it. It might even be getting hot enough that black anodising and radiative cooling would become significant. In no conceivable situation where a "thick" piece of aluminium (i.e. thicker than a foil) was anodised would you see that sort of reduction in conductivity. Andy Dingley (talk) 12:31, 31 August 2015 (UTC)

M S DIVEKAR (talk) 11:30, 1 September 2015 (UTC) Now let me share this conductivity problem with an example. You are welcome to compute yourself. Heat is generated by a body dissipating say 4 watts. For various reasons it is cantilever mounted along a aluminum strip- which for aesthetic reasons was beautifully anodized. Now will the heat travel along only the external anodized layer? Will thick core of aluminum of the cantilever ever be used at all? Unfortunately the inner core was not used and temperature rose to very high value. Pure solid aluminum was about 10 mm x 25 mm x 30 mm. The temperature drop between the ambient to other end of aluminum block was less than 1 deg C, but the body at the other end could go to even 40 to 50 Deg C higher than ambient. If the aluminum cantilever section is replaced with a solid NON-anodised body how much will be the rise in temperature? There is little scope for radiation here as it is IP65 sealed enclosure with glass body. Now let us see possibility of selective anodization where the hot body is directly in contact with the bulk of aluminum. I am sure you will find the temperature drop by over 30 to 40 Deg with reference to the ambient. No big mathematics needed to check differences.

I will attach drop box link to picture separately. https://www.dropbox.com/s/u1x55et1q6akzkj/pic.docx?dl=0

Hence in this specific case selective anodizing helps. There will be many cases where heat to is not transferred from hot body directly to ambient and so called heat sink is jsut a heat transferring trasnducer. Heat must be SUNK only in the ambient far away. M S DIVEKAR (talk) 11:30, 1 September 2015 (UTC)

M S DIVEKAR (talk) 08:36, 2 September 2015 (UTC) Now in the same example imagine the solid pure aluminum is replaced a with another anodized aluminum C Clamp as shown here. At the interface between two anodized surfaces one could expect a 10 to 15 Deg C temp drop!!!! This has been measured. Here is the link to modified sketch https://www.dropbox.com/s/u474gq3j60si6q0/CCLAMP.docx?dl=0.

So ultimately selective anodization is the BEST SOLUTION M S DIVEKAR (talk) 08:36, 2 September 2015 (UTC)

In your "bar heated at one end" diagrams, it's too awkward to solve that as a two dimensional problem, so instead let's consider it as a pair of one dimensional problems.

• In the first case, consider a long thin aluminium bar with an anodised surface along the long sides. It is heated at one end. It is cooled at the other. It loses no heat along its length. Imagine two bars, one plain and one anodised and compare their conductance.

The two cases are identical (within the bounds of experimental or modelling accuracy). The anodised layer is a thin layer. So the anodised bar is effectively identical to the first bar, wrapped in an anodised tube. Now we know that anodising has less conductivity, but also in this case we're looking at a situation where there isn't any heat loss along the bar anyway. So radial flow is negligible. Also the layer is thin, so the conducting core isn't reduced measurably in size.

• In the second case, we examine heat flow across a thin wide film of an anodised layer, into a bulk mass of aluminium. Again, we know that the anodised layer has less conductivity, but also that it is a thin layer. We can approximate it as a thicker layer of aluminium, with its extra thickness in proportion to the conductivities, relative to the layer thickness. So adding an anodised layer reduces conductance, but it reduces conductance by a tiny amount: comparable to an extra aluminium thickness of a fraction of a millimetre of extra aluminium. If we're talking about bulk aluminium, that's just not significiant - it's within the manufacturing tolerances of the heatsink.

So overall, we see that reduced conductance from anodising is: 1) theoretically evident. 2) If referring to a conductance through a film, then it's probably measurable. 3) Insignificant in engineering terms: smaller than manufacturing variations. 4) If referring to conduction in bulk aluminium with a surface coating, then totally insignificant.

There is just no drawback to anodising. Andy Dingley (talk) 10:15, 2 September 2015 (UTC)

In your C clamp example, is that temperature drop because of the interface? That's nothing to do with anodising. Andy Dingley (talk) 12:26, 2 September 2015 (UTC)

M S DIVEKAR (talk) 07:22, 4 September 2015 (UTC) I appreciate your analysis. As we all know that both electrical conductivity is high as well thermal conductivity is high in metals (let us not bother about anomalous effects in some). Therefore, I measured electrical continuity of aluminum strip – with and without anodization. I found electrically the anodized surface has very high insulation property. I did find that a non –oxidized aluminum surface- though appeared to have whitish with oxide formation did show low resistance, whereas the anodized aluminum surface showed infinite resistance. I did compute temperature drop using same equations- but assuming anodization as thick as 0.5 mm. Do note that I could not remove anodization even by scratching with a sharp knife. The temperature drop in this layer alone could go to 10 to 25 Deg against less than 1 Deg C, for pure aluminum. In my example with a C clamp there are two bodies between the heat generating source and the ambient- 10 a cantilever bar, 2) c-clamp. Both are anodized and in addition a anodized surface to anodized surface contact where one can find another 20 Deg C drop or more. These issues could totally upset the heat-sinking concept of a a callous engineer. Hence, I feel selective anodization must be raised in the main article on Heat sink. M S DIVEKAR (talk) 07:22, 4 September 2015 (UTC)

Although in metals both conductivities are high, this doesn't imply anything about other materials. Consider diamond or sapphire - both electrical insulators with high thermal conductivity.

Anodised aluminium is an oxide, it's an insulator. Not a reliable one in such a thin layer, but still much more so than a metal. Andy Dingley (talk) 08:52, 4 September 2015 (UTC)

M S DIVEKAR (talk) I do agree with you. I am only suggesting selective anodization in the context of aluminum heat sinks ONLY. I suggested electrical measurements- as a simple test- as most companies do not have facilities for thermal heat transfer measurements. It is the simplest and fastest measurement in the context- again of aluminum heat sinks only. M S DIVEKAR (talk) 05:56, 6 September 2015 (UTC)

Colloquial term?

I have removed the claim that heat sink is a colloquial term and the claim that it is never used in academic books. This is demonstrably untrue. Google books gets well in excess of 600,000 hits and the first listed is a a book actually called Heat Sink. Also on the first page of results is Horowitz's book which is widely used on Wikipedia as a reliable source by some electronics editors. Thinking the term may possibly be avoided in academic journals I tried Scholar and got in excess of 400,000 hits. These include multiple hits for the Journal of Heat and Mass Transfer (example) who one would think, if anyone, would be avoiding a coloquial term. There are also many hits for the prestigous IEEE Transactions.

It might be possible to say that the term heat sink as a component arises from the theoretical thermodynamic use of the term where it is opposed to a heat source, although I have no source to hand giving the etymology. Often, ideal sources and sinks are considered that can supply or absorb any quantity of heat without changing temperature, much as an ideal voltage source can supply or sink any amount of current.

I am not sure exactly what the source, Kordyban, has said on this, but apparently the book is written in a humorous style. Perhaps someone can provide the exact quote, but it should probably not be taken too serioulsy. SpinningSpark 10:08, 20 June 2010 (UTC)

Quick clarification

"But one of the advantage of copper is that it is less loud than aluminium." I am a lay on the topic; I read this and think of loudness as referring to noise level. Is that how it is meant? If so, why would either material make any noise? --75.67.157.198 (talk) 02:38, 2 December 2010 (UTC)

The other direction

How about heatsinks that are designed to operate in the opposite direction, i.e. transfer heat from the air to a cold object? An example would be this picture which appears in the Billycan article, a cooking pot with a heatsink welded to its base to trap as much heat from the stove as possible. Rwxrwxrwx (talk) 09:52, 26 December 2010 (UTC)

This is not genuinely a heat sink, it is a heat store. The definition of heat sink implies that there is only one direction of heat flow. Heat goes in from the fuel, but the metal is acting as a heat source as the heat goes out to the food. This is similar to the old-fashioned cooking pots with thick copper bottoms. At the very least, this need a reliable source (preferably journal publication) decribing this as a heat sink before inclusion is warranted. SpinningSpark 07:27, 3 March 2011 (UTC)

Linking to heat sink article

"Can I link to my website here? I have a lot of good heatsink illustrations." — Preceding unsigned comment added by Davidfarzam (talk • contribs) 23:26, 2 March 2011 (UTC)

No, we do not usually approve of links to uncontrolled private sites. You can, however, upload images if you are prepared to release them under a free licence. SpinningSpark 07:02, 3 March 2011 (UTC)

I have also removed the batch of three external links recently added. The first one is a calculator, which is not needed as the article already contains the design formulae. Calculators are often created by commercial web sites merely in order to generate links to their site rather than a genuine attempt to be useful and are particularly dubious when they fail (as here) to explain details of the calculation. The second one timed out on me and appears to be dead, at least temporarily (WP:EL#EL7, WP:EL#EL16). The third one is a power point presentation which would be most useful as an aide-memoire to someone who actually attended the lecture, but not here. The material is already adequately covered here and anything that isn't can easily be added. See WP:EL, especially WP:EL#EL1. SpinningSpark 08:10, 3 March 2011 (UTC)

Equation 2 Defination

In the section: Basic heat sink heat transfer principle there is an equation,

${\dot {Q}}={\frac {T_{hs}-T_{air,av}}{R_{hs}}}$ (2)

Where the value of R is not defined as to what it is. There should be some clarification. — Preceding unsigned comment added by Dabozz88 (talk • contribs) 13:33, 3 October 2011 (UTC)

Someone please fix this; its frustrating to come across explanations that you have to decipher yourself. 165.123.197.92 (talk) 01:26, 2 December 2013 (UTC)Anonymous

Undeclared Variable in Section 1

In the basic heat sink heat transfer principle section, the variable $c_{p,in}$ is not declared, and does not explicitly appear in the associated figure. Equation numbering is also done manually rather than using the LaTeX-based markup for equation numbering, which may lead to future inconsistencies. — Preceding unsigned comment added by Nummify (talk • contribs) 17:06, 17 February 2012 (UTC)

Undeclared Variable in Section 4.1

Lot's of variables used in equations from 5 to 13 are not declared, so these are not easy to use. — Preceding unsigned comment added by 80.13.11.187 (talk) 06:51, 12 June 2014 (UTC)

m n

what are m and n called, what are their units??????????? — Preceding unsigned comment added by 77.13.206.51 (talk) 14:27, 10 November 2013 (UTC)

Heat sink increasing efficiency of a circuit.

An editor, Burninthruthesky, keeps adding a reference that he insists states that a circuit becomes more energy efficient if a heat sink is added. That is, that the waste heat -v- the useful energy is somehow magically reduced. The references state that the circuit performs more efficiently when the heat sink is added. What the reference is saying is that the circuit performs better (efficiency as a measure of performance in this context) at its task. It does not say that the circuit magically dissipates less heat (which is impossible). A circuit dissipating 25 watts of heat will still dissipate 25 watts of heat of a heat when a heat sink is added. The temperature of the circuit will be lower, but that is because the heat sink is passing more of the energy into its surroundings. The energy dissipated is exactly the same and hence the ratio of useful energy to waste heat energy is exactly the same.

That is unless anyone can explain how adding a heat sink to a resistor or a circuit that is consuming (say) 100 mA, somehow causes it to consume less current because that is the only way you can improve its energy efficiency. 86.149.143.134 (talk) 15:35, 15 October 2017 (UTC)

From Resistive heating:

$P\propto I^{2}\cdot R$

R depends on temperature and all pure metals have a Temperature coefficient#Positive temperature coefficient of resistance.

So yes, less heat is produced when the resistor is cooled, even with constant current.

The material is well supported and has been in the article for years.

References

Burninthruthesky (talk) 16:37, 15 October 2017 (UTC)

Your argument has the position arse about face. Most resistors are made from carbon, and integrated circuits are made from silicon both of which, being non metals, have a negative temperature coefficient so they would actually consume more power by cooling them. It is usually the larger integrated circuits that are mostly equipped with heat sinks in any piece of equipment and seldom the resistors (Have a look inside your PC. Can you find a resistor with a heat sink on it? No? Didn't think so). Carbon resistors have a temperature coefficient of minus 8×10^-4 Ω/°C. Silicon (in its semi conducting form) has a temperature coefficient of minus0.07. So the waste heat from an integrated circuit would, in theory, rise by a considerable margin if cooled by a heat sink. However, for other reasons semi-conductor circuits have to designed such that they remain unaffected by temperature changes so, in practice, the power consumption remains practically unaltered. If you stick a wattmeter on the input to your PC, you will discover that its power consumption remains unaltered as it warms up. 86.149.143.134 (talk) 12:47, 16 October 2017 (UTC)

Some components can have their temperature coefficients engineered through materials selection, others are still made from copper. @Wtshymanski: "a heat sink just lets you get away with an inefficient circuit". The provided sources say the relationship between temperature and electrical efficiency works both ways:

Clearly higher efficiencies equate to less heat that will need to be dissipated, easing the problem of removing this heat from the supply. Nevertheless appropriate thermal management is still vital and can have a direct impact on the performance of a power supply. For example, electronic circuits often perform more efficiently at lower temperatures and will in turn tend to dissipate less energy as wasted heat.
— cui

Efficiency and reliability are partly the result of a power supply unit's designed cooling method.
— aegispower

Global initiatives for improved energy efficiency have forced engineers to makes improvements in cooling power supplies.
— aegispower

Your comments? Burninthruthesky (talk) 05:34, 17 October 2017 (UTC)

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