Longevity of thermally conductive adhesive tape - Page 1
Forum section: electronics / projects

author: daqq
author_rank: Super Contributor
timestamp: November 14, 2019, 09:14:13 am
content: Hi guys,I'm investigating the use of a thermally adhesive tape (such as these ones:https://uk.farnell.com/fischer-elektronik/wlft-404-48-x-48/thermally-conductive-foil-adhesive/dp/4695562) for use on a BGA to hold a heatsink on it.The ambient temperature will be around max 60°C, the device itself will be around 70°C, there will be some vibrations. What kind of life expectancy does this tape have when used in these kinds of conditions?Thanks,David

author: daqq
author_rank: Super Contributor
timestamp: November 18, 2019, 07:21:07 am
content: Bump?

author: magic
author_rank: Super Contributor
timestamp: November 18, 2019, 08:18:17 am
content: I can only say that PC modders and overclockers use that stuff to attach small heatsinks to GPU RAM, FETs and such. I don't recall seeing any warnings against it but it's not like I spend any significant time on those forums either.In fact, I have such heatsinks on the VRM in one computer. I believe it was 3M tape, rather thin. Temperatures like you would expect: rarely below 70°C, up to 100°C or more peak. Last time I checked it's all still there after a few years of useBut with vibration

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 18, 2019, 03:39:47 pm
content: I have used that occasionally and I can't say I would use it for very long term or stuff that works in harsh environments. OK for indoor stuff that doesn't move much IMO. YMMV.For more permanent solutions, I have used epoxy thermal adhesive. It's like epoxy glue, but thermally conductive. Drawback is, it would be very hard to remove the heatsink after that, if possible at all, if it ever matters.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: November 18, 2019, 03:55:22 pm
content: Some LED guys use thermally conductive silicones such as the STARS-922, available for 25 cents per tube on Aliexpress. It provides a happy medium between serviceability (capable of or being of service; useful) and serviceability (capable of being used, worn, cleaned, repaired, etc., easily).

author: magic
author_rank: Super Contributor
timestamp: November 18, 2019, 04:01:48 pm
content: Frankly you could probably use any kind of glue. 10°C difference between the device and air doesn't sound like much heat will be moving through that sink.Quote from: SiliconWizard on November 18, 2019, 03:39:47 pmFrom my experiments with IC decapsulationI can say that vinegar damages some epoxies but not those used in IC packages. So perhaps that, if it ever happens that you must. Otherwise that stuff is incredibly resistant.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 18, 2019, 04:06:53 pm
content: Hmm, well, I've used a few of these heatsinks with included adhesive,Thermal vias join the LED thermal slug to the heatsink. (The prototype one is epoxied.)Only has to hold against gravity, but it doesn't budge when I bend on it a bit. Was weak at first; hard to bear any kind of pressure against the stuff, but over time I think it kind of flows like capillary action.Tim

author: georges80
author_rank: Frequent Contributor
timestamp: November 18, 2019, 04:38:50 pm
content: I've used adhesive thermal tape for many products.Many of the good quality material uses acrylic adhesive and you will find that it requires a period of time with pressure applied for it to set. 24 hours is usually the time it takes for the acrylic adhesive to full set and achieve maximum adhesion. You need to apply pressure for a few minutes initially.Decent products will have install information in the datasheet including performance specs.Cleaning surfaces is of course critical for good results. There are different types of material as well, some conductive (the graphite type) and some are gap filling (will flow to some extent).cheers,george.

author: daqq
author_rank: Super Contributor
timestamp: November 20, 2019, 07:04:49 am
content: Thanks guys for the great replies! I'll try using this heat cure epoxy:https://sk.farnell.com/mg-chemicals/8329tcs-6ml/adhesive-2part-epoxy-syringe-6ml/dp/2811937The heatsink will never come off hopefully

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 20, 2019, 07:26:11 am
content: Reminder to clean the surfaces well, and, hm, the datasheet doesn't say anything about surface prep for aluminum so it may do well as-is, or not, Idunno. Could check mfg site if they have any additional info about that. Worst case, probably the good old technique can be used: wet-sand the aluminum surface with the epoxy itself, then make the joint.Point being, aluminum often doesn't bond well, presumably because of its surface oxide layer. A chemically clean bond can be made by scraping off that oxide, under cover of something that resists oxidation, hence using the wet epoxy.Hehe, not that you need much strength to hold a small heatsink onto a BGA.Tim

author: roy5
author_rank: Newbie
timestamp: November 21, 2019, 08:17:26 am
content: How well do you need it to stick? If you need good adhesion and never intend to remove it again, there is always thermally conductive epoxy such as the one from RS in the link belowhttps://uk.rs-online.com/web/p/thermal-adhesives/1558320/

author: magic
author_rank: Super Contributor
timestamp: October 12, 2020, 03:34:12 pm
content: Quote from: magic on November 18, 2019, 08:18:17 amNecro-updateI regret to inform that the tape pretty much gave up and the heatsinks are now flapping around in the breeze, barely hanging from the motherboard.According to my archives, I purchased this tape in early 2016 and probably applied it soon after. So that's 4 years.I don't have any P/N (auction site) but it was supposedly 3M brand, rated for 130°C, 50µ thickness.

author: David Hess
author_rank: Super Contributor
timestamp: October 13, 2020, 07:29:27 am
content: I have never seen thermally conductive tape fail, but I have not trusted it either.Quote from: T3sl4co1l on November 20, 2019, 07:26:11 amI have always found anodized aluminum to be one of the easier things to bond with epoxy. Clean with acetone.

author: magic
author_rank: Super Contributor
timestamp: October 13, 2020, 07:37:32 am
content: The tape stayed stuck to the MOSFETs but the heatsinks (anodized alu) have mostly separated from it and tilted down.They are narrow and relatively tall (3cm or so) and the board is mounted vertically, so there is a constant force pulling on one edge of the contact area.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2020, 07:38:52 am
content: Quote from: David Hess on October 13, 2020, 07:29:27 amFor what it's worth, the pictured flashlights are still firmly attached to their heatsinks, this is after three years now. Again, essentially no load. The heatsink does seem to be rigidly attached, enough that I think I would crack the base board if I tried twisting it off. I'm sure it can still be pried off its substrate with a thin blade.Maybe they will fall off next year?QuoteLast stuff I did, using hardware store "2 ton" epoxy and solvent-cleaned surfaces, easily peeled away leaving no residue on the aluminum. Sanding it in, it was at least as strong as the fiberglass I was bonding it to (which also tended to peel away or delaminate -- damn this G10 having a polished surface, I had to sand it too).There are industrial formulations that actually bond aluminum and other materials without special prep, just not what's available at the hardware store.Tim

author: David Hess
author_rank: Super Contributor
timestamp: October 13, 2020, 08:27:08 am
content: Quote from: T3sl4co1l on October 13, 2020, 07:38:52 amThe hardware store stuff is pretty terrible. 907 is not a thermal adhesive but more typical of what works well in this sort of application:https://miller-stephenson.com/product/ms-907-two-part-epoxy-adhesive/https://www.amazon.com/Loctite-Hysol-gram-Epoxy-Adhesive/dp/B000WXDLAQ