Best thermal interface - Page 1
Forum section: electronics / general

author: daniel444
author_rank: Regular Contributor
timestamp: March 07, 2019, 07:08:58 am
content: Hi, im currently using arctic silver thermal grease on the backs of some bridgelux vero29 cob leds im mounting on some aluminumis there anything better i could be using ?specifically thishttps://au.element14.com/t-global/t62-150-025-100g/graphite-sheet-0-25mm/dp/1372950it claims to have 20W/m.K , better than arctic silver at 5W/m.Kthere is some other even thinner 1000W/m.K sheets but those me be to thin to handle ?

author: The Doktor
author_rank: Regular Contributor
timestamp: March 10, 2019, 09:36:56 pm
content: Those super high performance thermal compounds are only worth it, IMHO, when you have a very high density heat source. Certainly they are worth the cost when you have something like an exposed die of a CPU contacting a heatsink , and they do give you a few degrees less operating temperature on a CPU with a heat spreader. But those LED COBs I would consider to be a fairly low density, well spread out heat source. For mounting them, I normally use something more affordable such as this Super Lube 98003https://www.amazon.com/Super-Lube-98003-Silicone-White/dp/B0044NI2M2which is under $7 for 3 oz. I just don't believe the fancy stuff is going to give you any advantage in this situation.

author: rdl
author_rank: Super Contributor
timestamp: March 10, 2019, 10:55:49 pm
content: If all you're using now is grease with no insulator, and it's applied correctly, there will be plenty of metal to metal contact and no air gaps. I doubt any solid interface material will even come close for actual thermal resistance.

author: wraper
author_rank: Unknown
timestamp: March 10, 2019, 11:07:27 pm
content: Quote from: daniel444 on March 07, 2019, 07:08:58 amKeep in mind it has 0.25 mm thickness, thus will suck compared to any decent thermal paste. You shouldn't buy arctic silver either. It's old product, very expensive and not particularly good. Better get Arctic MX-4. Although it's a bit more expensive than MX-2 for the same weight, however it's lighter and you will get much more paste for the same weight. Also it has better thermal conductivity and easier to spread.Also as already said, if it's not something with huge energy density per area like CPU, you should not care about thermal paste that much. Any inexpensive thermal paste will just work fine.

author: daniel444
author_rank: Regular Contributor
timestamp: March 12, 2019, 02:51:21 am
content: Quote from: wraper on March 10, 2019, 11:07:27 pmthanks for the advice , ill get some mx4 , do you think it will last a long time in service because some of the cob leds could last 20 years ?

author: wraper
author_rank: Unknown
timestamp: March 12, 2019, 11:31:32 am
content: Quote from: daniel444 on March 12, 2019, 02:51:21 amThey claim at least 8 years without any degradation on the package. I don't think there will be any problem.

author: nctnico
author_rank: Super Contributor
timestamp: March 12, 2019, 11:46:10 am
content: Quote from: wraper on March 10, 2019, 11:07:27 pmDefinitely not. Graphite (carbon) is one of the best heat conducting materials.The graphite sheets from Farnell have a conductivity of 20W/mK where the Artic MX-4 tops out at 8.5 W/(mK).

author: wraper
author_rank: Unknown
timestamp: March 12, 2019, 12:11:14 pm
content: Quote from: nctnico on March 12, 2019, 11:46:10 amDid you not see word "thickness"?. It has 2.5 times better thermal conductivity, but you have 0.25mm of material which has 20/10 times worse thermal conductivity than copper/aluminium. On the other hand, layer of thermal paste is an order of magnitude thinner.