really proper way to apply thermal compound? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: December 09, 2018, 11:03:42 pm
content: If you really wanted to do this, is there a better method then the 'baboon fishing for ants' way we normally do it by smearing it around with a fine brush?If both surfaces are super clean, would it not be better to do something like place a frozen sphere of the compound (or hemisphere) in the center of the die, warm it up so it flows, then compact it warm and use a precise jig to clamp it down to some known seperation distance?What is the crazy semiconductor manufacturers way of doing this? Maybe spinning a layer on it like a photomask?also can vacuum degassing possibly get rid of air bubbles if combined with warming? or possibly replace voids that are normally air filled with voids filled with more thermally conductive solvent present in the thermal compound?

author: IanB
author_rank: Super Contributor
timestamp: December 09, 2018, 11:13:38 pm
content: The purpose of thermal compound is to displace any air between the mating surfaces (air is a better insulator than the thermal compound, which we hope is a thermal conductor). Therefore the best way to apply thermal compound is as a small blob in the center of the mating surfaces and then compress the surfaces together so that the blob spreads out sideways displacing air as it goes. (If the surfaces are large then maybe one or more beads might be better than a single blob.) It also wouldn't hurt to smear the surfaces first with a very thin layer of compound to remove any pockets of air in the surface pores and assist the spreading process.Overall, the thinnest layer of compound possible would be the ideal as thermal compound does not conduct heat as well as metal does.(Note, it is not a good idea to spread the compound before mating the surfaces as this will cause pockets of air to be trapped and will reduce the heat transfer efficiency.)

author: coppercone2
author_rank: Super Contributor
timestamp: December 09, 2018, 11:17:21 pm
content: i wonder if the lapped surface should be measured first with a surface texture gauge, then a thermally conductive compound of grit size appropriate to fill the voids is used (non appropriate for the larger connection), lapped off, then the proper thermal compound applied that possibly has different properties since it works to fill a different bulk geometric profile rather then micro cavities.

author: coppercone2
author_rank: Super Contributor
timestamp: December 09, 2018, 11:19:16 pm
content: Quote from: IanB on December 09, 2018, 11:13:38 pmI thought this was the best method but I thought I was advised against it some where before. I did not understand why, I thought maybe its because if you have a giant blob rather then a thin layer you get some kind of point stresses that end up causing the compound to separate out under the increased pressure that would not be present if spread out more. I wonder if a domed mold used with chilled compound could spread it out more from the beginning with less peak pressures.

author: DaJMasta
author_rank: Super Contributor
timestamp: December 10, 2018, 12:20:03 am
content: The recommendations I've seen for lapped surfaces and optimal cooling are generally:Smear a very small amount of the compound, less than opaque thickness, all over each side, then connect (optionally with a small amount in the center). This does require very flat surfaces and every even pressure applied, because if either isn't right there will be air gaps with no contact, but since TIM is generally less thermally conductive than the metals it sits between, the idea is to minimize the amount while still getting maximum contact area.Generally, the surfaces aren't exactly smooth so you need a little leeway in the application, I've seen a fair number of techniques, but some options are:Smear around and dot in centerPea sized dot in the centerX over the contact areaX with dots in each quadrantDots over each die (if you know where it is) with or without a smearEven opaque application (if you just want to guarantee complete contact)Not 100% sure on what would be the "best", but there are some reasonable options depending on the surfaces. Worth noting that different TIM compounds probably prefer different applications - more viscous compounds will not spread as much under the same pressure, so more frequent smaller dots or similar would be preferable. Nice thing about the even smear is that it doesn't have to move around much.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 12:25:57 am
content: how do you find air gaps? what test is used for it? freeze disassemble and do surface inspection?

author: IanB
author_rank: Super Contributor
timestamp: December 10, 2018, 01:13:37 am
content: Just measure temperatures. The purpose of heat sinks and cooling systems is to cool the device producing heat. So measure the temperature and make sure it is within expected limits. Many devices have an onboard temperature sensor to make this feasible. If the temperature goes too high something has gone wrong.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 01:32:10 am
content: that only means your trying to meet a spec not see whats actually going on. how would you actually measure it to ttune a process?

author: IanB
author_rank: Super Contributor
timestamp: December 10, 2018, 01:40:58 am
content: You do science. You have the hot temperature in the device being cooled, you have the cool temperature on the outside of the heat sink, you can do math to find out the heat transfer resistance of the thermal compound and compare that to expectation.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 01:49:47 am
content: that won't tell you if something happened like a density change due to lack of proper 'suspension' vs air gap. Or contaminated fluid with some kind of larger particle etc.Say viscosity change due to pressure change that causes a suspension to break down or something.

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 01:50:17 am
content: I have some experience with using LOCA adhesive for attaching touchscreen to display where I could actually see the result. I can say that the best way is is to apply it asX. It's the best way to fill all of the space with minimum amount of paste and avoid air bubbles at the same time. If you apply only drop at the center it will spread as circle and space you need to fill is not round. So either drop needs to be huge (a lot of paste will squeeze out) or it won't fill the corners.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 01:54:02 am
content: it spreading out does not create microbubbles in it because it kind of tears as it spreads on a microscopic level?I don't think this stuff is very fluid like, like the glue is. It's more like a suspension I think, like chocolate chips in a dough ? Are you sure there is not some kind of sheer surface forming that can introduce a void? Or kind of like surface evaporation or other effects making a surface thats kind of like a cake thats beginning to bake in the oven where the very skin is stiffer, and if you poke it with a knife you get cracks. Like imagine you just put a dollop of muffin compound on a baking tray, broil it till the surface gets kinda solid, then smush glass down on it. I think you will have voids because of the cracks.I am also weary of using a transparant surface as a window because the surface tension of the whatever is different so it might behave differently.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 10, 2018, 02:01:46 am
content: Relevant:https://www.infineon.com/dgdl/Infineon-AN2006_02_Application_of_screen_print_templates-AN-v1.0-en.pdf?fileId=db3a304412b407950112b40ed3f71297Tim

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 02:04:24 am
content: Quote from: coppercone2 on December 10, 2018, 01:54:02 amThat adhesive is not really that fluid. It's more fluid than thermal paste but not nearly like water. The trick is that air bubbles are not entrapped because touch/spreading of adhesive or paste starts from single point thus pushing all air out.

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 02:10:53 am
content: Quote from: T3sl4co1l on December 10, 2018, 02:01:46 amThis way is good as well. It provides routes for air to escape. But you won't do this well without properly designed stencil.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 03:00:04 am
content: I still think the glue is a true solution but the other stuff is a colloid at best.

author: DaJMasta
author_rank: Super Contributor
timestamp: December 10, 2018, 03:47:52 am
content: As for checking for air gaps, using regular thermal material will generally show you the outline of the bubble when you remove it to reset it, but I'm not sure how to know before you remove it aside from seeing a temperature that's too high and deciding there was probably a problem with the application.Most of the reason commercial products or coolers with TIM pre applied come with the thick sheet of heatsink compound (which is often internally reinforced with a mesh) is that the thickness and width ensure a fairly even, full coverage installation. I think virtually none of the time it's the ideal low thermal resistance connection, but it is consistently reliable at making a decent connection, so if the rest of the thermal design is done around that assumption, automated assembly or end-user assembly and all its variables can still get reliably good results.

author: Nerull
author_rank: Frequent Contributor
timestamp: December 10, 2018, 04:09:05 am
content: These guys tested several application methods and found differences of a fraction of a degree on high-wattage CPU applications.People obsess over methods of thermal compound application but real word differences seem minimal to non-existent.

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: December 10, 2018, 04:32:59 am
content: Quote from: Nerull on December 10, 2018, 04:09:05 amI change the CPU/GPU paste on several computers every few years, either because of an upgrade or just regular preventative maintenance.I use Arctic Silver, and the 2-part Arctic Clean. My steps are, using gloves throughout:* clean the surfaces gently but thoroughly with cotton buds, and then lint-free laboratory wipes (Kimwipes or similar;* let dry for at least 30 minutes;* apply the paste to the CPU with a glossy business card (new in box, untouched); spread in X, Y, and X-Y directions so it's a thin even coat;I don't use the edge, I bow the card in half and use the soft bend as the spreading surface;* install the heatsink; this step usually squishes the paste a little but not much;* run a thermal benchmark, to test the installation.What I find, each maintentance cycle, is that the previous coating was quite even with no obvious voids, and the benchhmark gives reasonable temperatureson the fully loaded system.So yes, do it with care - don't scratch the surfaces, and do a proper clean - but don't obsess either.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 10, 2018, 05:30:27 am
content: A good way to ensure even coverage and exclude air is to apply the thermal paste in an 'X' pattern then clamp the heatsink on.This will make sure the thermal paste reaches the edges but won't capture air.On the other hand, ESAB welders specify to apply a small amount of heatsink compound then dab it around with the flat end of a small foam paint roller until a thin even coating is achieved. They even supply the paint roller with the tube of thermal paste in the kit.If that process is good for IGBT modules passing hundreds of amps, I'm sure it'll be ok for a CPU or vreg etc.On the topic of lapping, apparently 1200 grit emery paper leaves grooves that are approximately the same size as the silver particulates in Arctic Silver 5 thermal paste. Anecdotally, this should mean the silver is able to more effectively fill the gaps and make a close thermal interface.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 10, 2018, 05:38:25 am
content: This discussion seems to reappear over and over and never seems to be conclusive. There are a few popular camps with have valid points on paper, but which in practice don't seem to make any distinguishable difference. Pick what works for you and be happy with it.

author: GregDunn
author_rank: Frequent Contributor
timestamp: December 10, 2018, 06:00:59 am
content: Quote from: Nerull on December 10, 2018, 04:09:05 amThis. If it were really important, they wouldn't give thermal compound, CPUs and heat sinks to gamers and trust them to not screw it up.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 10, 2018, 06:10:24 am
content: Quote from: GregDunn on December 10, 2018, 06:00:59 amI suspect the typical demographic of the target group is a large part of the ongoing discussion. Teen men with a point to prove aren't quite known for their nuanced discussions and factual opinions.

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 06:27:09 am
content: whats interesting about CPU is the fact that you can replace the paste between the die and the lid of the IC in a modern intel chip to improve its performance. surprising for 1000$ ic.but seriously, what about spin coating? Its used for extremely even distribution of photoresist during transistor manufacture.

author: jbb
author_rank: Super Contributor
timestamp: December 10, 2018, 06:32:12 am
content: In the high power semiconductor line, screen printing a pattern of small diamonds (or similar) on seems to be common.For Some systems (eg automotive) we are starting to see devices which have fins or pins for water cooling built right into the bottom plate. No heatsink compound anywhere!

author: Ian.M
author_rank: Super Contributor
timestamp: December 10, 2018, 07:09:01 am
content: Take an old credit card or store card and scrape a trace of compound over both surfaces to fully wet them. Wipe off any excess at the edges. Apply a dot in the middle (rice grain size for most power transistors, dried split pea sized for large ICs like old Pentium CPUs) and assemble with manual pressure and a slight orbiting motion till you see squeeze-out all the way round. Fit the retaining clips or screws before releasing the pressure. If possible clean up the squeeze-out excess with a paper towel or a Q-tip moistened with thinners.If you pretend you are Scrooge and the paste is loaded with gold dust you'll get the quantity about right - meaner than a Scottish miser spreading Marmite - as the thinner the layer the better as long as its void-free.

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 01:39:30 pm
content: Quote from: GregDunn on December 10, 2018, 06:00:59 amIf it's a bare silicon die, it's important. From my experience I can say that I've seen GPU shutting down due to local overheating (but showing normal temp in monitoring app) which happened because of entrapped air bubble (just after paste application). If paste is spread over surface, some small air bubbles are almost guaranteed.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 10, 2018, 07:53:44 pm
content: Quote from: wraper on December 10, 2018, 01:39:30 pmHow did you make sure that was actually the problem you saw? Just reapplying thermal pastes leaves room for many other issues to be corrected at the same time.The problem with this discussion is that it's surrounded by a lot of myth and hearsay whereas the little repeatable actual evidence that exists shows pretty much all of that is irrelevant. More evidence is very welcome, but we should be very mindful about what is accepted as such.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 10, 2018, 07:55:03 pm
content: Quote from: coppercone2 on December 10, 2018, 06:27:09 amMost of Intel's higher end offerings once more come with soldered IHSs.What about spincoating? It isn't currently remotely applicable to CPU TIM.

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 08:34:02 pm
content: Quote from: Mr. Scram on December 10, 2018, 07:53:44 pmBecause it was newly applied thermal paste and there was an air bubble. When you are dissipating 250W of heat at 95oC die temperature over 4cm2without any heatspreader, it matters.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 10, 2018, 08:37:16 pm
content: Quote from: wraper on December 10, 2018, 08:34:02 pmThat's a bit anecdotal to be honest. By reinstalling the heatsink you change many variables. Maybe the pressure or mounting was different, who knows.

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 08:58:52 pm
content: Quote from: Mr. Scram on December 10, 2018, 08:37:16 pmYou cannot make a different pressure with that heatsink and springy backplate on the opposite side. Pressure applied is a constant amount, period. And how pressure would matter to begin with? And I say it again,there was a freaking air bubblewhen I disassembled it.EDIT: And that graphics card would not go over 95oC which is target temperature. It would increase fan speed and throttle.

author: langwadt
author_rank: Super Contributor
timestamp: December 10, 2018, 10:55:08 pm
content: Quote from: TERRA Operative on December 10, 2018, 05:30:27 amyeh just like when laying tiles using a notched trowel always make parallel lines so you don't get any closed pockets of air

author: coppercone2
author_rank: Super Contributor
timestamp: December 10, 2018, 11:02:46 pm
content: people will desolder their processor lids and snap off glue with special jigs. look at the process on youtube, I have seen a high end AMD processor go into a pizza/toaster oven.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 10, 2018, 11:50:20 pm
content: Quote from: wraper on December 10, 2018, 08:58:52 pmI don't have trouble believing that you saw an air bubble upon disassembly. The issue is the implied causation based on a single uncontrolled observation. That's tentative in the best of circumstances and probably worse in a matter where discussions tend to be endless in lieu of hard repeatable evidence.

author: wraper
author_rank: Unknown
timestamp: December 10, 2018, 11:53:54 pm
content: Quote from: Mr. Scram on December 10, 2018, 11:50:20 pmIt's quite obvious that heat transfer will suck through air bubble. And with such high amount of heat dissipated from small area it's obviously will have severe effects.

author: coppercone2
author_rank: Super Contributor
timestamp: December 11, 2018, 12:10:40 am
content: can you do a ultrasonic reflection test?

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 11, 2018, 12:14:47 am
content: Quote from: wraper on December 10, 2018, 11:53:54 pmThe videos provided before show that these kind of common knowledge factoids in reality don't have the impact some people purport them to have. Things like the method of application, partial TIM coverage or too much TIM turn out to cause differences well within the margin of error. This means the results are effectively the same across the board. Even though conventional knowledge says these factors should make a difference, they don't appear to do so.That makes it not as obvious that an air bubble would have an effect. The only reasonable conclusion seems to be that there isn't enough information to draw conclusions, although it should be noted that none of the other factors did make any difference. Your anecdotal observation could be the starting point for a more controlled investigation, though.

author: wraper
author_rank: Unknown
timestamp: December 11, 2018, 12:21:50 am
content: Quote from: Mr. Scram on December 11, 2018, 12:14:47 amThose tests are done with CPUs which have heat spreader, thus bubbles have much less effect. Not to say, you won't see temperature increase in monitoring software if bubble is not above the area with temperature sensor.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 11, 2018, 12:53:38 am
content: Quote from: wraper on December 11, 2018, 12:21:50 amI agree that there may be different circumstances, but without any kind of controlled testing it's quite impossible to say whether a bubble can make these kinds of differences or not.

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2018, 06:45:12 pm
content: I just smear a thin even coat with my finger. Too much paste is a common mistake and is worse than too little.

author: wraper
author_rank: Unknown
timestamp: December 13, 2018, 07:22:12 pm
content: Quote from: james_s on December 13, 2018, 06:45:12 pmUnless it's a conductive crap, too much paste won't do anything bad, excessive amount will just squeeze out. Well, unless you apply so much that it gets into CPU socket. Too little can cause actual problems.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 13, 2018, 07:27:23 pm
content: Quote from: james_s on December 13, 2018, 06:45:12 pmThe video already posted shows even a rather excessive amount has no discernible impact. The conclusions really does seem to be that all these hard fought wisdoms of the internet turn out to be made up lines in the sand to fight over. Everyone needs a hobby, I guess.

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2018, 07:44:57 pm
content: Too much paste makes a huge mess all over everything, and in the case of power transistors I've replaced failed transistors that had so much paste that they weren't sitting flat on the heatsink. Also those silver types tend to be conductive, I repaired something that was malfunctioning due to conductive paste oozing out on the leads.

author: wraper
author_rank: Unknown
timestamp: December 13, 2018, 08:12:47 pm
content: Quote from: james_s on December 13, 2018, 07:44:57 pmIf transistors were not sitting flat, it's certainly not because of the amount of the thermal paste. But because they were not mounted properly or were not tightened as should.QuoteYou need to buy that crap specially. And those are not even among the best in regards of thermal conductivity of modern thermal pastes.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2018, 08:32:29 pm
content: I developed a theory.The thermal paste is rather abrasive. If you get it into your thread then it will mess with your torque readings. You can't tighten the thread right unless its cleaned and maybe oiled (bit better). If you put gobs of thermal grease over a part that can get into a torque sensitive adjustment screw it might prevent you from clamping.It should not be an issue with overhead springs though.Maybe this is how it all started? It seems like you can do it to a TO-220 easily.Keep in mind standard bolts (not metrological or special use) come in 5 grades of tolerances and probably surface finish (but this is not controlled as well), and I don't know how threads are listed.If the thread is really ratty and unpolished chances are you will compress a asparity of the metal, which will yield over time and actually reduce spring force. Also even if you tighten by extension you can have some stuff creep out of the threads if it gets in there after a while or from evaporation and cause the torque to change. Also the derivation of torque from rotation requires stable known geometry as a constant I believe to be applicable to bolts. I might check this laterThis is why you never use ratty old sealant on nice pipe threads I think. Also, you use teflon tape. Its pretty slippery stuff. Its not aluminum oxide impregnated rough tape.If you take something rusty apart its a good idea to use new bolts but if not be sure to brush them good to derust and give a slight polish and then lubricate and clean out the thread hole. For small bolts you can kinda wing it by taking a pair of wire cutters to a dremel brush to make a smaller dremel brush. But properly you would wanna use a rethreading tool, or re-tap the hole with a bigger size (re-threader / thread cleaner) is different then a new tap.. or if you need the same size drill a bigger hole and insert a heli spring thread insert.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 13, 2018, 08:37:41 pm
content: Quote from: coppercone2 on December 13, 2018, 08:32:29 pmWhy are you suddenly going off on a tangent about threads and spring force?

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2018, 08:43:31 pm
content: Quote from: Mr. Scram on December 13, 2018, 08:37:41 pmI don't know why you don't understand the context but to explain it in clear detail:1) There is some crap about using too much thermal grease being bad other then non economic2) there is a claim insufficient mounting pressure is a result3) there is a claim this is non sense because it should work and mechanically cannot be explained4) a partial explanation is offered by the mounting geometry of certain packages being susceptible to contamination if excessive thermal grease is used5) there is a detailed explanation about the functioning of bolts and screws for those that did not read very boring literature about proper screw function (going off about)yea im 'going off' maybe try to follow the discussion?I noticed that people who are not mechanical engineers, and most engineers in general that I spoke to, don't really appreciate the mis behavior of threads from contamination. Plenty of people think "yea its real tight that means its good".but idk do you say that to your wife when she complains you left your socks on the floor? 'shes going off' ............

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2018, 08:45:01 pm
content: Quote from: wraper on December 13, 2018, 08:12:47 pmI didn't mount them, I just cleaned up the mess. These were arcade vector monitors with big TO-3 transistors that screw into flimsy stamped frame sockets.

author: fsr
author_rank: Regular Contributor
timestamp: December 13, 2018, 08:47:36 pm
content: I just use an old credit card to spread the paste over the entire contact surface. It takes some time, but won't make a mess with the paste when tightening, and seems to work without problems.

author: wraper
author_rank: Unknown
timestamp: December 13, 2018, 09:35:00 pm
content: Quote from: james_s on December 13, 2018, 08:45:01 pmPlease explain how thermal paste can be responsible for gaps? Did I say anything about who mounted them?

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2018, 10:21:07 pm
content: well it can seperate and change density

author: james_s
author_rank: Super Contributor
timestamp: December 13, 2018, 10:31:24 pm
content: Quote from: wraper on December 13, 2018, 09:35:00 pmA thick glob does not always squeeze all the way out, it has some thickness. After removing the transistors I have often seen a thick layer of the stuff, as thick as a piece of paper easily. Not a huge gap but not zero either. Biggest problem though was it made a greasy mess. There is no reason to glop on a ton of it, a little goes a long way.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2018, 10:34:27 pm
content: why? If you measure torque and the threads are clean you should put a surface at a particular pressure.If you have too much grease why would it not work? How does the mechanics of the grease behave ? I am not saying you are wrong but I don't understand it.You are applying a feedback force, with a torque wrench. What you are saying is true if you basically pulsed energy into the system without feedback... but you don't do that with a screw driver, the time constant of the stuff seeping out from under the package and stabilizing should be much faster then the screw driver..I think about the simple model this way: your hand is the voltage source and your eyes on the torque wrench scale or click of the wrench is the sense wire. You can still get the correct voltage drop despite the increased resistance of flow.I am trying to think about this in terms of deformation and nonlinear forces, maybe there is something else at play here. This is exacty why I started the thread to learn if there is something like that. Some kind of pseudo phase change, mechanical separation, state of matter type thing (kinda far out), etc.Like a non newtonian fluid will resist a impact, if you slam it with the screw driver, but if you are slow it should work the same? Just check to make sure torque did not change after a while and bring it to the same torque... it would have to some how change in its parameters...does this stuff maybe have really really low frequency non newtonian behavior (or what ever the proper term is to describe the impulse sensitivity of non Newtonian fluids towards flow).

author: TinyMirrors
author_rank: Contributor
timestamp: December 13, 2018, 11:11:27 pm
content: I'm probably late to reply. This is my favorite way to put on thermal compounds.I put two pieces of scotch tape on the thing I want to put compound on. Like drawing two parallel sides of a rectangle with the tape leaving an area between them to put the compound.Then use a razor blade or credit card to scrape the thermal paste between the two pieces of tape.The tape keeps the razor blade at a very low height as you scrap making a really thin layer of thermal compound.Pull the tape up and have a nice bordered area. If you're really good you can mark off a square with the tape but I'm never that patient and use two pieces of tape.| | | ||T| |T||A| Compound |A||P| |P||E| |E|| | | |

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 13, 2018, 11:11:47 pm
content: Quote from: coppercone2 on December 13, 2018, 08:43:31 pmMaybe people have trouble following your reasoning because of the badly formatted and written posts, with subjects that may or may not have to do with what's discussed? Please take some care when writing a post, instead of giving people an attitude.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2018, 11:52:22 pm
content: your giving the attitude bitching about having to read

author: wraper
author_rank: Unknown
timestamp: December 14, 2018, 12:03:30 am
content: Quote from: james_s on December 13, 2018, 10:31:24 pmThick blob squeezes out just as well as a thin blob, with barely any resistance until only a thin layer is left. TO-3 package not sitting flat most likely means that heatsink/package was not completely flat and/or one screw was tightened at full force and then opposite screw tightened when package was already lifted on one side. Nothing to do with thermal paste. Actually a small amount of thermal paste would mean there would be air in that gap, thus thermal transfer being even worse.

author: glue_ru
author_rank: Contributor
timestamp: December 14, 2018, 03:18:47 am
content: wow, you need a life

author: james_s
author_rank: Super Contributor
timestamp: December 14, 2018, 06:28:36 am
content: Quote from: wraper on December 14, 2018, 12:03:30 amLook you can speculate all you want, I'm only reporting on what I've found. I've repaired probably 50 of these monitors and most had been worked on multiple times over the years. I found a lot of transistors with thick layers of thermal paste on them that had not squeezed out, this is just plain fact that I saw with my own eyes and scraped off with my own hands. Maybe the paste they used was thicker than the modern stuff, I don't know, the monitors were 20-30 years old when I dealt with them.It's always funny whenever someone tries to tell me something isn't possible when I'm the one that has seen it, do you think I'm lying?

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2018, 06:42:06 am
content: maybe bad threads so the operator cant squeeze the part down?did they work right when you tightened them down? did you check to make sure the screw hole was drilled deep enough and the screw was going all th e way in?

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 14, 2018, 09:49:22 am
content: And was the hole deburred and slightly countersunk?

author: wraper
author_rank: Unknown
timestamp: December 14, 2018, 11:21:58 am
content: Quote from: james_s on December 14, 2018, 06:28:36 amNobody told you have not seen it. I say you make wrong conclusions. It's quite easy to mount TO-3 not flat even without any thermal paste present at all. And yeah, if it was a monitor, I guess that heatsink was rather small and quality of mounting didn't even really matter. They probably failed due to crap design, not because of bad thermal transfer between transistor and heatsink.

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2018, 04:28:40 pm
content: another idea I had is maybe there are some larger clumps of thermal compound that require higher peak pressures to smash (like when you sift flour) and if there is alot of it to begin with you don't mash it well because the pressure is less.

author: wraper
author_rank: Unknown
timestamp: December 14, 2018, 04:37:48 pm
content: Quote from: coppercone2 on December 14, 2018, 04:28:40 pmIn such case it's place is in a trash can, not on a heatsink.

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2018, 05:24:55 pm
content: well then what explains this behavior. Put some play dough in vise if you don't believe me. It should work regardless of how much you put initially.

author: coppercone2
author_rank: Super Contributor
timestamp: December 14, 2018, 05:25:46 pm
content: if that dough figure was like 3 feet tall would it matter at all?imo NO