Micro porous heatsinks? - Page 1
Forum section: electronics / projects

author: nctnico
author_rank: Super Contributor
timestamp: August 20, 2017, 07:19:02 am
content: I have come across a kind of heatsink I have not seen before. The manufacturer claims it works because it is porous and thus has a large surface area.http://www.farnell.com/datasheets/2198326.pdfHas anyone used these in a force (fan) cooled application? My gut says the small holes get clogged up with dust.

author: alm
author_rank: Super Contributor
timestamp: August 20, 2017, 01:47:03 pm
content: What kind of unit is w/mk? Is that supposed to be W/mK? Kind of worrying if a heat sink manufacturer / distributor can not even get the figure of merit right.My guess is that the air flow impedance is so high barely any air will flow through the heat sink unless you have a fan designed for a very high static pressure with a sealed tunnel between fan and heat sink. If anything, it might perform superior to traditional finned heat sinks in very low airflow passive setups where convection is the main source of cooling. But obviously only a well designed tests can determine this, since apparently the manufacturer is unable to provide any technical details.

author: tszaboo
author_rank: Super Contributor
timestamp: August 20, 2017, 02:46:04 pm
content: Specification said 5-6W/mK thermal conductivity. That is 80 times worse than copper.It tells, that they dont specify K/W figures for their heatsink.But here is their appnote:http://www.amecthermasol.co.uk/datasheets/MPC303025T.pdfSo whoptee doo, it is better than a 2mm thick copper or aliminium heatsink on a BGA. 2mm.And it can even cool a Geforce2 400 by 10 degrees. No, that is not the geforce 400. That is a video card, which came out in 2000, without any heatsinking.

author: amyk
author_rank: Super Contributor
timestamp: August 20, 2017, 03:29:00 pm
content: Works OK -> Gets clogged with dust -> Temperature rises -> Parts failBeing practically impossible to clean, these are essentially designed for forced obolescence.

author: nctnico
author_rank: Super Contributor
timestamp: August 21, 2017, 01:26:24 pm
content: Meanwhile I ordered various heatsinks (ceramic and aluminium) and see which one works best. AFAIK ceramic can have a very good thermal conductivity. Many high power (RF) circuits are build on ceramic substrates which are then glued onto heatsinks.

author: Ian.M
author_rank: Super Contributor
timestamp: August 21, 2017, 01:48:30 pm
content: Beryllium Oxide is the 'bees knees' of ceramics for thermal conductivity (which is the only reason its high toxicity risk is tolerated).Fromhttps://www.americanberyllia.com/beryllium-oxide:QuoteThere's no toxicity warning for the AMEC Thermasol MPC ceramic, so unless they are heavily loading their ceramic with diamond dust*, there is no way it can out-perform a chemically blacked copper heatsink of equal size with the top surface microgrooved to double its surface area.* In that case they'd be advertising it as a diamond heatsink as it would be crazy not to claim premium materials

author: tszaboo
author_rank: Super Contributor
timestamp: August 21, 2017, 02:38:30 pm
content: I think "good thermal conductivity" means it is better than FR4. Anyway, let us know if you made any testing and how it went.

author: DBecker
author_rank: Frequent Contributor
timestamp: August 21, 2017, 03:44:13 pm
content: Quote from: Ian.M on August 21, 2017, 01:48:30 pmI used to speculate that when aliens came down and took orders for large diamonds, I shouldn't request jewelry. I should put in an order for a frying pan. Followed by a windshield.Diamond heatsinks now have to added to the list. I wonder how effective fine diamond dust in a sintered matrix would be -- if it would beat copper. Even a relatively expensive material can be cost effective for die-contact heat spreading.

author: SeanB
author_rank: Super Contributor
timestamp: August 21, 2017, 04:32:01 pm
content: Would ask the aliens for some high temperature ( at least 150C upper limit) superconductor, preferably in a sheet form, and some monomolecular wire. Superconductor as heat spreader would be a lot better

author: tszaboo
author_rank: Super Contributor
timestamp: August 21, 2017, 05:04:21 pm
content: Quote from: DBecker on August 21, 2017, 03:44:13 pmThe very fine industrial diamond is cheap. This heatsink is about 10 gramm, that is 50 carat, and industrial diamond goes for around 0.3-0.5 USD/carat. So about 15 USD, if 100% diamond. But there will be some bonding material. And no, I dont think that they can create a diamond heatsink from a single crystalline.

author: CopperCone
author_rank: Super Contributor
timestamp: August 22, 2017, 08:28:35 pm
content: Quote from: SeanB on August 21, 2017, 04:32:01 pmmankind is not readyIf size is not an option, I wonder if you can put a electrostatic dust collector. It would be interesting to investigate the clogabiliy of both systems.It could temporarily reverse air flow and disable the field to vomit dust all over the intake area and hopefully run for a long time. lmfzao. or fire up an incinerator circuit to burn the dust and reduce its volume.Don't filters drive you insane? You have to constantly think about what filters are clogged or keep schedules and logs of everything. It's like instituting another beurocracy in your home.unfortunatly dust is sometimes radioactive. what a menace.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 23, 2017, 12:57:59 am
content: Quote from: DBecker on August 21, 2017, 03:44:13 pmNope: just barely not.https://www.almax-easylab.com/PCD.aspxPCD is cheap and popular for inserts and coated tools, used to machine hard, nonferrous* materials.*Iron dissolves carbon when heated, so you can't run high surface feedrates (and thus high point-contact temperatures) with the stuff. No advantage. You use carbide for steel: you can turn hardened steel with carbide, curling off red-hot, stringy chips! ("Carbide" is actually cemented carbide: WC2 powder, "brazed" together with 10% Co.)Tim

author: Kleinstein
author_rank: Super Contributor
timestamp: August 23, 2017, 04:40:45 pm
content: Quote from: SeanB on August 21, 2017, 04:32:01 pmSuperconductors are usually poor heat conductors. With the electrons entering the super-conducting state they no longer participate in thermal conduction. There might be an extra heat flow from generating / splitting cooper pairs. But generally the thermal conductivity goes down when going superconducting - so much as using some metals switched between normal and SC state by a magnet to make a kind of thermal switch. Super good thermal conduction is in the superfluid state - but this is very low temperature helium, thus cold enough for most electronics anyway.At 5-6 W/m/K the porous ceramics would compete with the thermal paste and even stainless steal is about 3 times higher in thermal conductivity.

author: dorin
author_rank: Contributor
timestamp: August 23, 2017, 05:20:13 pm
content: Maybe it's meant for liquid flow?Otherwise, if it's just meant to be passive the internal cavities do not contribute to cooling surface area in any way, they just decrease the thermal conductivity of the whole thing.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 23, 2017, 07:26:03 pm
content: If you want a high surface area, liquid cooled material, you might try aluminum and copper foam, open cell. AFAIK, the thermal conductivity and pressure drop is worse than a properly made heatsink.A similar material can be made from sintering large metal particles, but it's not known for its fluid flow capability; indeed, quite the opposite. Oilite(R) (sintered bronze, oil impregnated) is famous for its ability to retain liquid.Tim

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: August 23, 2017, 08:16:42 pm
content: Quote from: Kleinstein on August 23, 2017, 04:40:45 pmTsk, tsk, tsk! Are you really advocating the use of unlawfully obtained materials here?Especially doubtful, as such 'wares' are generally called 'hot' rather than 'cold'.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 23, 2017, 08:27:46 pm
content: Quote from: Neomys Sapiens on August 23, 2017, 08:16:42 pmIf it'sstainless, I guess you can't get caughtred-handed at least.Tim

author: nctnico
author_rank: Super Contributor
timestamp: September 04, 2017, 10:18:47 pm
content: I tried the micro porous heatsinks but they are not doing much.

author: tszaboo
author_rank: Super Contributor
timestamp: September 05, 2017, 07:05:36 am
content: How did you attach it?

author: ChristopherN
author_rank: Unknown
timestamp: September 05, 2017, 05:58:22 pm
content: I ordered some, they come with a 3M pad.I'll try to test them within the next days.