Name: Product Demo | A New Method to Measure Thermal Conductivity: Thermo-Optical Plane Source (TOPS) | Presented by Laser Thermal
Uploaded: 2025-05-06T17:30:05.916Z
Duration: 38 min 32 s
Description: Product Demo | A New Method to Measure Thermal Conductivity: Thermo-Optical Plane Source (TOPS) | Presented by Laser Thermal

Transcript for "Product Demo | A New Method to Measure Thermal Conductivity: Thermo-Optical Plane Source (TOPS) | Presented by Laser Thermal": In addition to high thermal conductivity, it has characteristics such as electrical insulation and flame retardancy. Sarcon is currently used as a thermal interface for electronic components in a wide range of industrial applications. First, we will briefly explain the functions of Sarcon. The surfaces of the heating element and heat sinks have fine irregularities. If they overlap directly, there will be a gap. The gap is what prevents the heat flow. Since the surface of SARCON is very soft, it has good conformability and the gap between the heating element and the heat sink can be filled evenly. By using SARCON, efficient heat transfer can be achieved. Furthermore, since the SARCON is so compliant, it has high heat transfer performance even in large gaps between substrates with complicated shapes on which various chips are mounted, as well as curved surfaces. Next, we will introduce the types of SARCON. SARCON can be classified into four types, rubber type, gel type, honey type, and form and place type. Some of these types also have other features. We will introduce the characteristics of each type. Sarcon rubber type is a high hardness, thermally conductive silicone rubber. The rubber type materials have excellent electrical insulation, high reliability, and make full use of various characteristics unique to silicone rubber. It can be molded into various Hey, Curtis. This is the tech team. You're just on mute. My goodness. I did it again, you guys. You know, we've all been through 2020. That was five years ago when we started Zoom and Teams meetings, and here we are. I'm still on mute. So sorry about that, guys. Welcome back to Thermal Live. In this session, we're gonna explore a new technique called the thermal optical plane source or TOPS method. This process enables rapid steady state measurements with minimal sample preparation across a wide range of material types and geometries. Our presenter, Jeff Braun, is vice president of programs and strategy at Laser Thermal, and he leads government and commercial r and d efforts and also holds a PhD in mechanical and aerospace engineering. Laser Thermal develops cutting edge solutions to develop the thermal properties of materials, to to analyze the thermal properties of materials, driving innovation across industries. So Jeff's gonna join us now and present. Jeff, welcome to Thermal Live, and sorry I was on mute. Thank you so much, Carrie. Yep. Take it away, Jeff. It's all yours. Appreciate it. Thank you for having me. As Curtis mentioned, my name is Jeff Braun, and I've been working at Laser Thermal to develop, this new product that you see here called thermal optical plane source or TOPS for short. So I'm happy to dive in now. So to begin, I just wanna mention a little bit about our company, Laser Thermal, and why we exist. So in my experience in both academia and industry, I've noticed the difficulties of obtaining thermal properties in general from experimental data. In in general, you have to be an expert in the methodology itself to extract good data, whereas in most cases, the end user just wants to be able to get the data they need to for their application and have confidence in that data. And so we as a company exist to, to streamline the the process of obtaining thermal property data, and making it as simple to the user as possible, so that they can focus on what's important to them, which is the the properties themselves and, the research and development or quality control that they're doing. And so we worked with, a variety of leading organizations to verify our our techniques. We started with thermal reflectance based techniques and have since moved to more bulk scale applications in the form of the TOPS measurement I'm going to talk about today. So, on that note, our company currently has three product lines. The first of which we launched was the FASTR product line, which is a a thermal thermal reflectance space metrology. That's primarily used for, semiconductor industry in the form of measuring thermal conductivity and, heat capacities of of thin film materials. But we've since branched out and developed two other product lines. On the macro scale, we offer this new technique called TOPS, which is capable of measuring everything from solids, liquids, pastes, gels, on the macro scale, and it's gonna compete with, traditional techniques like hot disk or ASTM d fifty four seventy, things of that nature that you may be familiar with. Going on to the next slide, this is kind of a picture of where we stand as far as spatial resolution of our technique and how it compares with others. So on the nano scale, again, we have two techniques down below the our thermal reflectance space. And on the, upper end on the macro scale packaging level, we have this new technique we're calling TOPS. So let's talk a little bit more about how this works and the package it comes in. So, fundamentally, TOPS is an infrared thermography based technique. We use a a laser to heat the surface of a material. We We typically prep that material with, emissivity, coating, which comes in the form of a simple adhesive that we supply, to standardize the surface properties of the material. We then, use the laser to heat the surface of material and measure the temperature rise, as a function of the spatial area. And so on the middle, you see an example of what that temperature rise looks like. We heat it to a steady state temperature so that the balance of laser power and, temperature rise in the material is constant, and we take that as a function of laser power. And if you think about Fourier's law, the thermal conductivity of a material is simply the proportionality constant between the heat heat flux you supply and the temperature gradient within that material. So we're exploiting that property to measure thermal conductivity. In practice, here's what some of the data looks like. In this case, we have fused silica sample that was coated with that emissivity layer, and we vary the temperature in real time by, increasing the laser power to extract that relationship between temperature rise and laser power to extract them quantity. What this means in practice is that, we're able to circumvent a lot of the, pain points that traditional, methodologies have imposed in the past. Particularly, we offer rapid testing times and, eliminate the the sample prep that's required for a lot of these traditional techniques. We're we're insensitive to sample geometry for the for for the most part and, sample size and, very few restrictions on what types of samples that you can actually measure with this technique. And so what this means in practice is unmatched simplicity, very reduced cycle times. You know, we can measure, thermal conductivities on the order of seconds. In worst case scenarios, on the order of a couple of minutes. And, ultimately, what we do is simplify the measurement to make it automated for you to to take the burden out of your hands so that you can focus more on accelerating your own innovation of your materials, get faster cycle times, improved r and d and quality control. So I won't go through the details of what this slide shows, but we will have these available for you to to parse through. But in in short, TOPS offers an unprecedented, capability that is unmatched by traditional techniques that are widely used in industry. And so you can go through at your discretion and see kind of the advantages that TOPS offers, but I'll point that out too that we are direct measurement of thermal conductivity insensitive to material properties like density and heat capacity, which is a big plus for this this methodology. And we're, fundamentally measuring, local thermal conductivity so you can get spatial variation if you have an inhomogeneous sample, for example. So those are two big advantages, but you can go through some of the others at your own discretion. And then from a data validation perspective, here we show some examples of, thermal conductivities that we've measured, And you can see we spend five orders of magnitude in in capability with the same instrument with no modifications, and we get very good agreement between literature values and what we're capable of measuring. So with that, I'll thank you for your time, and we can proceed to the demo portion of this event. Welcome to Laser Thermal. Today, we're gonna go through a tutorial on how to make a TOPS measurement. So you can see we have a variety of different samples already prepped, having different shapes, dimensions, thicknesses, from foams to metals to, acrylics. And Nick's gonna show us first how to apply our transducer film to the sample. Hello. So here is the transducer film, and I'm gonna be applying to an example of the bulk material that we would normally test here at, Laser Thermal. So the first thing I'm gonna do is I'm gonna take this film, and there's these little corners that have been engraved into this film itself. I'm going to peel up this corner. I'm gonna start to pull up the edge of the film. I'm gonna start to lay it on top of my bulk sample and pull the film over. And it's okay if you see a few wrinkles right now. That's not a problem. So that's why I have it overhanding the edge a little bit. It makes it a little bit easier so I can now lift the edges, pull it taut, kind of like tensioning a drum head, pulling it taut, pulling around, and it does not have to be 100% perfect because remember our spot size is right around one millimeter. So as long as I have a good three millimeter spot where I can get my laser in there, everything will work out fine. And this is an example of a prepped sample. Okay. So now that we have applied the transducer film to our, bulk sample, I'm gonna pass off the sample to Jeff, and he is going to proceed to take the measurement in our Tops machine and determine the thermal conductivity. Thanks, Nick. So, yeah, so the sample has been prepped. And at this point, we'll open the door and place our sample into the machine, and you'll see that the stage has an engraved target to make it easy for you to apply the sample where it needs to be to be centered on our infrared image. So I'll go ahead and close the door, and we can see now that we're we're starting to see some contrast indicating that the sample is visible. What we need to do from here is adjust the stage height in order to focus the sample. And we have a rule of thumb as to where to place the stage position based on the height of the sample, but I know from experience that for a sample this height will be around 30 millimeters. So I'll just go ahead and move the stage roughly where it needs to be, and we can start to see some contrast in the image indicating that we can see our sample surface. At this point, I'll go ahead and turn the laser on. For a conductive sample like this, we won't see anything at low powers, but if I max out the power of our laser at a 10 milliwatts, we can start to see the heated region of our sample. So I'm not quite in focus. We'll know we're in focus when the heated region is perfectly centered in our infrared image, so I'll go ahead and at this point run our alignment procedure. So I can go up to alignment and press autofocus or hit ctrl f on the keyboard as a shortcut. At this point, the TOPS tool will take over and adjust the stage height in order to center the position of the laser on the infrared image. So you can see the procedure is finished and we can now zoom into our image and see how well the procedure worked. Seems like we got pretty close, but we might want to do some fine tuning, so we'll go ahead and adjust this just by a few pixels just to get perfectly centered, and you'll see, from the crosshairs and comparison to the position of our heated region that we're pretty close, but we can go ahead and check that by going up to alignment check center just to confirm that we are indeed centered on our image. In the diagnostics tab, we'll see an output of the center coordinate and we're looking for somewhere around three twenty by two forty as our center of our image. So we do a good job here. We know we're centered. At this point, I can go ahead and turn off the laser and proceed to my measurement. Before I do so, I'm going to go ahead and name my sample, so I'll just call this test sample and I'll adjust the measurement parameters. So we have here four different parameters to adjust the average time, wait time, the number of points, and our max power. So to adjust the max power we first wanna see what the temperature rise we're getting at our laser power is. So to do that, I'm gonna go ahead and first go to IR camera tab and subtract image and what this does is subtracts the current frame from all future frames so we can get rid of noise at the sample surface and just see temperature differences when we turn our laser on. So I'm going to go ahead and turn our laser on at max power. We typically recommend a measurement to be around five degrees Celsius and temperature rise, but in this case we're already maxing our power out and this is a conductive sample, so we're only getting around 3.3 Celsius, so it's good enough to make a measurement, so we'll just go ahead and use the max power we have currently as our measurement power. So I'm going to go ahead and turn this laser off, un subtract my image, and then I'll go over here and set my max power to 110 milliwatts. As far as the averaging time goes, this is the amount of time we we take to make a single point measurement. So when we turn our laser on, we wait a certain amount of time and then we average for a certain amount of time. So for a conductive sample, you know, we we only need about five seconds of averaging time and five seconds of wait time. For an insulating samples, you may want to, increase the wait time further and so you can ensure your sample reaches steady state. And this is something that you'll get a a feel for as you measure more samples, but typically around thirty seconds is is good enough for most samples, even the most insulating ones. Okay, so with that I have my measurement parameters defined. I'm using five seconds averaging time, five seconds wait time, a max power of a 10 milliwatts. I'm going to use a typical number of points of being five, but if you wanted to push your measurement to be faster, you could use two points and likely get a similar value. So at this point, I'll go ahead and measure my sample. So I'll press the measurement button. We'll see a progress bar, pop up showing the measurement in progress, and if I move that to the left, I can see the current real time data of the temperature rise, and we see that it starts with no laser power applied, and then, we turn on the first laser power, and we wait five seconds, average five seconds, and then we apply that same procedure at increasing powers. And with each new, point obtained, the software will show the current value of thermal conductivity, but what what it's doing is fitting a model to the current data, and as you get more points of your data, that number will be refined. So at each, at each point we refine the data and get a new value. So at this point we're 80% complete, we have one more point to go, and we've just finished our measurement. So once the measurement's complete, the value of the thermal conductivity will be printed along with the sample name in the diagnostics tab, and the results will be, printed to the table in the bottom right. And so all all proceeding tests will, do the same thing where they the software will print the sample name as well as the thermal conductivity in the bottom right here. And if I if I highlight any file in this table, it will show me the data to that file in the plot. So that's it. We've made our first TOPS measurement. And to summarize, we started with taking our bulk sample and applying the transducer film. Then we took our sample and placed it into the TOS machine so we could determine the sample's thermal conductivity. We adjusted the stage height in order to focus the sample in the IR camera, and then we adjusted the measurement parameters to make a thermal conductivity measurement. Please reach out to Laser Thermal if you have any questions or inquiries about the TOPS system and technology. We're confident that this TOPS measurement will help you innovate better and faster, paving the way to your success. Thank you. Thank you. Alright. Hey. Thanks. That was amazing. I'm fascinated by that, and I'm sure, those of you watching are as well. So thanks, Jeff, for that exploration. And as Jeff mentioned previously, you can access the slides from this presentation. You can find them in the docs tab next to the chat for this session. So now as you can see, Jeff is here to answer some questions. Are you ready, Jeff? Absolutely. Thanks, Curtis. Okay. Here we go. You will see these on the screen. This first question says, is is the TOPS technique suitable for layers? What about liquids? Yeah. That's a great question. The answer is yes with some caveats. So in general, we can measure all sorts of materials, composites being one of them. And if you're interested in, differences between different areas of your your composite, that's something we can do with a a precision on the order of, about a millimeter or so because we're we're basically measuring the, spot of our laser, at the end of the day, and our laser is on the order of of a millimeter in diameter. So if you see any differences in your properties on that, scale, we can locally probe those differences. And then, indeed, we can even generate a thermal conductivity image of sorts to, show you the local differences among your sample. Going to the layered question, that is something we can do. We we become restricted below about around hundred microns in terms of sensitivity. But beyond that, assuming we can, kind of adapt the thermal model to, you know, properly model the situation that you have. So if you have, for example, a a a layered material on a substrate, we can adapt that thermal model to capture that layer. And as long as you know the substrate properties, we can then, you know, just fit for the the layered property. And then in terms of liquids, that's something we routinely do. We we supply the user with a a vat that they can insert their their liquid. We, have it so that you can apply the transducer material, fill the vat, up to the the transducer and up run the measurement as if it were a solid. So we make it very easy for the user to to do that process. Fantastic. Yeah. Okay. So our next question says, does this, technique measure bulk thermal conductivity, or can it be used to measure local differences in thermal conductivity as well? Yeah. So like the composites question, fundamentally, we are measuring, around a millimeter spot. So we can call that an, more of an in in situ measurement of thermal conductivity if there are variations. But for for non or for homogeneous materials, that that will be indicative of a bulk property. Great. Okay. So our next question asks, what is the emiss emissive emissivity, help me with that, of this film, and what is it what is it made of? Does this add any thermal resistance? I will I'll leave this question up here for a while because it's four questions. Yeah. Sure. That's a great question. So the emissivity, it so it it appears black in color, and our wavelength range of the camera's on the order of eight to 14 microns. It's in that wavelength range. It is, close to one. We've characterized it. It's more or less a black body. You can think of it. It's a a five micron layer of, a polymer based material. And so it is because it's a polymer, it is insulating, but because it's only five microns in thickness, it poses very little thermal resistance to most materials on the order of the measurement size of our our spot diameter. Where it does become a problem is when you go to higher than, say, on the order of, let's say, a hundred watts per meter kelvin materials. So, metals, silicon wafers, things like that, then it becomes restrictive. But we can apply the technique with alternate transducers potentially to to mitigate that. But, yeah, in in anything lower than that, it it poses very little thermal resistance. Gotcha. And so, the last question says, how is it compensated? Did you just answer that in the in your previous question? Well, yeah. It where it does pose resistance, we actually do, it's part of the thermal model that's happening in the background. So, fundamentally, we are, the the thermal model we use is a layered structure. So we we have the transducer layer and then any subsequent layers or bulk materials you have underneath. So that's why in the previous question, when we talked about, can we model, layers, The answer is yes. We're that's kind of fundamentally built in to what's going on in the background. It's just that we always have that one layer in the form of the transducer. Makes sense. Okay. So this next question, speaking of the transducer, it says, does the applied transducer film not influence the result? That and that that is the premise of the the model that we use is that, that transducer film does not, influence the result, and we can confirm that, within that band that I showed earlier of validated thermal conductivity values that we we account for that, and any propagation of uncertainty due to that film is going to be included in our model. Great. Okay. Next question. We got a few more. Says, how fast can a measurement be taken? Yeah. This is a great question. So the the answer is it depends on the thermal conductivity of the material itself. For anything above around five watts per meter Kelvin, the we're typically looking at a measurement time as fast as, five to ten seconds. For anything in more insulating than that so I'll go to the worst case scenario, where you have highly, or very low diffusivity material. That's kind of the worst case you can get because, fundamentally, what we're doing is we're waiting for the sample to reach steady state, and that's gonna be indicative of the diffusivity of the material. So in the worst case, something like acrylic, we have to wait around thirty seconds for that to happen. So we typically run it up to about a minute to make a measurement. So we're looking at anywhere between five to ten seconds up to a couple of minutes depending on how many points you'd like to do. Great. Next question says, does the chamber adapt to exterior temperature to keep constants from chip movement from outside to inside? That's a great question. If I if I understand it correctly, do we compensate for any temperature fluctuations from the outdoors is what I'm is what I'm understanding. And the answer is yes. So we do have electronic components in the the enclosure itself that contribute to some some temperature rise. So there might be some difference between ambient temperature and inside of the chamber, but we, fundamentally, we are measuring what that temperature is in real time. And so, typically, it's only maybe one or two degrees above the ambient on the outside within the the the chamber. But, you know, that's something that we are capturing in real time. So when we report a thermal conductivity value, it is at a given temperature. Great. It's getting lots of good questions. And just to remind everyone, if we don't get to your question during this q and a time on video, we'll make sure that Jeff and his team get these questions afterwards, and they will follow-up with you. So our next question says, can this method be used to measure thermal conductivity of PCB? Yes. We've actually done this in in the lab. We we've actually used it to not only measure the the PCB itself, but, quantify some of the buried, traces underneath a a PCB by, again, taking advantage of the the fact that we are a local measurement and kind of mapping where on the the the PCB we are to see kind of where those those very traces lie underneath the sample. So we we we have done that, and we're currently exploring kind of what those applications look like beyond just thermal or kind of, defect detection and and things of that nature. Awesome. Alright. This next question is interesting. We're getting real thin here. Is the method sensitive enough to measure the thermal con conductivity of glass layers, of thickness of a few hundreds of microns? Yeah. This is a really interesting question, and it's actually something we've been exploring recently. Basically, what what we can do in the case of thin glass, is is two two types of approaches, and we've we're kind of exploring both at the moment. One is to adapt thermal model so that we simply measure the glass as is, maybe suspended over air or even on a conductive, substrate to what in which we know the properties. And in that way, we can kinda force the heat to either go in plane or cross plane depending on if it's suspended in air or or on a conductive substrate. So as long as we can adapt thermometer, yes, we can we can do it. But that comes with some uncertainty, when you go, say, down to a hundred microns, we found. The other approach is we could layer them, so you have glass on glass on glass. And once it becomes thick enough, you can measure it as if it were a bulk material, and we've done that in the past as well. Great. Okay. So our next question says, can this be used to measure large samples? I assume that for a large conductor, the temperature rise would be low at a 10 megawatts, milliwatts? Sorry. Yeah. Yeah. That's a a great question. The the answer is we can measure large samples. So large being, on the order of one foot by one foot by, I think, around four inches in height is kind of the max we can fit into the chamber. But, yeah, the the power we have is currently limited to a 10 milliwatts in the commercial product. We do we do offer, contracts testing as well where in which we have, you know, a a a bit more power available in the lab to do, specialized measurements like that. But, yeah, we it's something we can definitely accommodate in most cases. Great. Okay. We got a a few more a few more questions here. This one asks, how is the bottom surface of the sample being cooled or temperature controlled during the test? Yeah. Great question. So in our case, we don't need to do much on that front because we are putting in so little power. And so, basically, with because we mentioned in the demo that we recommend just a delta t for the measurement of only a few degrees Celsius. By the time that heat gets to the backside of the sample, it's basically at room temperature everywhere except that locally heated spot. So that's the benefit of doing a local measurement is we can we can heat a small area of the sample while keeping the rest of the sample essentially at at room temperature. So we don't need to do any active cooling because the temperature rises we're inducing are so low. Great. Okay. Few more. Probably about three more, Jeff. Great. This is Alright. Keep it going. Okay. You're doing a great job, man. This says, does this technique use temperature difference between points at a certain time or certain laser power or temperature difference between a certain point at different times, different laser power? Does that make sense? Yeah. I I think I I understand. So yeah. Because I showed earlier where we collect the data in real time as a function of temperature. So, we I showed that you you see the temperature ramping up in time, ramping up in time. But then what we do with that data is we then extract it as a function of laser power. We take the the only the temperature once it's reached the steady state and convert that into a single temperature representative of that power step. So we take average temperature at an average power and plot that, against each other, and that relationship is how we extract thermal conductivity. Great. Alright. The next one says, can it measure effective conductivity of a vapor chamber? That is a very interesting question. The answer is I do not know. We have not tried. If I had to put my, kind of if I had to guess, I would say it will depend on the the range of that effective thermal conductivity, but it's very in theory, I would I would think it would be similar to measuring, a liquid or or or a a gas of some sort. So in theory, the principle can apply as long as that that vapor is, you know, contained in in its container and something that we can ensure is, you know, we can accommodate the transducer and container to to use in the top system. But quite frankly, I don't know. That's a that's a great question and just an application that we've never explored. I was gonna say what's the, what's the end application there, but that's that's fascinating. Very Here's the last question. It says, how does it work with anisotropic materials? Yeah. Yeah. This is a a great question. So, fundamentally, what we're measuring with this technique for both materials is the determinant of the thermal conductivity tensor, because we're our temperature profile is essentially a sphere in a semi sphere in the the material. We're we're heating it from above. We're inducing a a semi spherical temperature rise below, and so we're gonna be sensitive both to the crossplane and inplane thermal conductivity Where we can do some tricks, if you're interested in anisotropic properties is if it's a thinner than one millimeter, we can either suspend it in air to force everything to go in plane, all the heat to go in plane, in which case we're more sensitive to that in plane thermal conductivity, or we can put it on a conductive substrate to kinda force the heat to go cross plane. So there are certain things you can do to, kinda get after that anisotropy if that's something you're interested in. But from a fundamental perspective, for bulk materials, we we are measuring simultaneously both in plane and cross plane thermal conductivity. Cool. Man, seems like an incredibly innovative technique that you all are working on at Laser Thermal. So, thanks again, Jeff, for presenting today. If you all want to learn more about Laser Thermal, I dropped the link into the chat. It is laserthermal.com. Easy enough. So that's gonna wrap it up for this session. Our next session, which will be presented by today's master sponsor, Henkel, will begin at 01:00PM eastern time, and that will be in about ten minutes. So we'll see you then. Thanks, Jeff. Thank you.