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Podcast: Len Allison on Flexible Printed Electronics

Flexible Printed Electronics - Len Allison - EMS - Steve Davis - Tapecon

For the inaugural episode of the Better Product Solutions Podcast, Steve is joined by Len Allison from Engineered Material Systems to discuss flexible printed electronics, changes in materials, ASTM standards and the overall durability characteristics that make this a reality. Watch the video or read the full conversation transcript.


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Steve Davis [00:00:00] Flexible electronics is a pretty exciting space to be in right now, with a lot of brand owners looking to incorporate flexible print electronics into their designs. And there's a ton of great materials coming out right now that's going to really improve durability of taking really traditional printed thick film circuitry and really starting to infringe upon traditional flex circuits. So I'm really excited to have Len Allison, from Engineered Material Systems here. We're gonna be talking about a whole bunch of changing things on the material side, ASTM standards, and just overall durability characteristics that I guess just make all this stuff a reality. So it's a wide ranging conversation across all of those topics. And this is Episode 1, guest number one, and I'm really excited to have Len and have you all listen to what Len has to say. So my name's Steve Davis, I'm the president of Tapecon and this is the Better Products Podcast. Thanks for joining us. 


Steve Davis [00:00:56] Len, welcome to the show. Episode 1, guest number one. Happy to have you here. Len from Engineered Materials System. So, Len, welcome to the Better Products Podcast brought to you by Tapecon, so thanks very much for being here. 

Flexible Printed Electronics - Tapecon

Len Allison [00:01:10] My pleasure. 


Steve Davis [00:01:11] On your background. So tell us a little bit about yourself, and I guess your company and just wherever you want to start. 


Len Allison [00:01:19] Be happy to, be happy to. Well, I've always said a technical bent. I'd always get in trouble for taking watches apart at home, but I have a mechanical engineering degree from Michigan State. Been lucky enough to work in the conductive materials field pretty much all my career, which is 30 plus years of electronic materials for print electronics and other things. And 10 of those years were spent in Asia, which was a wonderful experience. I get to live in Japan and Singapore. Looking at what they do for print electronics as well. So I bring that experience back here as well. 


Steve Davis [00:01:57] Well, you've always struck me as technical, and I said that just when we were just having lunch. I mean, I feel like there's business development salespeople and then there's technical salespeople. And you've always struck me as being on the technical side of things, which I've always appreciated. So we've been, you know, we talked prior to this about, you know, what we want to talk about, and you introduced a new concept to me for my consideration, which I thought was great, durable printed electronics. And I've, I've always identified, obviously I'm well aware of printed electronics, but you helped me, I guess, maybe step away from it and look down a little bit about in terms of flexible electronics as just an orbiting ethos, and then all the little subsegments underneath flexible electronics and printed thick film circuitry in specificity which were going to talk about. But can you just give me, I guess, what is durable printed electronics and why is it important? 


Len Allison [00:02:50] Durable printed electronics with conductive films, or conductive inks and adhesives over the years has always been competing with copper circuitry. There is a rigid circuit board portion of the market. There's a flexible copper circuit portion of the market. And then there's polymer thick film or conductive ink portion of the market. And the material sets for printed electronics have improved over the 30 years that I've been in it to the extent that they pass sharp creasing tests, mandrel tests with surface mount joints, high potential voltage withstanding tests, etc. And so the durability of these printed inks and adhesives has grown to a level today where we can compete with any kind of copper circuitry out there and even outperform them. 


Len Allison [00:03:51] The things that I was talking about, I can quickly demonstrate on a switch like this where most people would like to be able to take an ink and crease it maybe ten or fifteen times, something like this, or with a surface mount joint, you might have something where you, excuse me, you light it up, right, but you should be able to really, be able to, to really beat these things up and not have them fail for you. 


Len Allison [00:04:26] So that's what the technology has done over the last 20, 30 years to improve to this level, which I think as an industry, it gives us a chance to compete more with the copper circuitry that's out there, which is a much bigger market. 


Steve Davis [00:04:39] Right, and even like before that, it seems like there's been almost a reputation amongst design engineers or people that that maybe PTF or printed thick film circuit approach to printing is not as durable, right? 


Steve Davis [00:04:52] I mean, generally it has had its limitations. 


Len Allison [00:04:55] That, that's been the, the picture that's been painted, in my opinion. This is an issue for me. I've been a part of all the ASTM associations. Started with Membrane Switch, became part of SGIA, and now it's a part of the IPC group. And most of these specs were written again 30 years ago. And when they were written, you know, the inks were pretty old then and we didn't have the level of durability and the kind of performance we have here. So a lot of these specs that are still in place today are written as if it's a real delicate thing. Print electronics or Membrane Switch or PTF circuitry on polyester film. And I don't think it needs to be that way anymore. As a matter of fact, I think as an industry, we have to set the bar higher because this, this kind of performance that I just demonstrated is possible. 


Steve Davis [00:05:48] Yeah, and I remember I was talking to one of our manufacturing engineers before this and specifically said, you know, creasing is one of the biggest failure modes that we'll see where you get it out in the field and someone wants to install it, but the person doing the installation doesn't know any better, or hasn't been properly educated. There's the bend and then there's the failure right? On the standards. So what specific test standards, are those, now that's, you mentioned IPC, ASTM and there used to be, you know, Membrane Switch, like the Membrane Switch symposium, as we were talking about before, used to have standards, committees. What's the state of those standards committees? Do those standards committees even exist right now with, in the Membrane Switch symposium or other types of standards committees? 


Len Allison [00:06:28] Yeah, they do. Very much so. 


Len Allison [00:06:30] But they're part of the IPC group, as a matter of fact, next week there's a IPC meeting. It's called Apex out in San Diego and I'll be there for that. And they've adopted all of these ASTM standards and are building on them and hopefully taking them to these new levels. But they're also writing new standards for things like e-textile, where standards aren't even written. 


Len Allison [00:06:55] And I kind of equate that to 30 years ago when I first got involved with this, the Membrane Switch group, which was a small fledgling group. They didn't even have standards at that time. So it was a really good effort where everybody would get together, say, "What do we have to do to prove to our customers that this stuff is viable for the market?" And so we came up with some ideas for different types of tests in that we had to develop the test, we had to write it up. So everybody said, yeah, that's about right. Then everybody well, we would choose people to go off and test according to the standard that we just made. And then they'd come back and report on it. Was it good? Was it bad? Did it tell the story or not? So it, you know, over the years it's been good. So we put standards in place that end customers can look at and say, "okay, now I know my product is good." You know, it's competing on a world class scale. 


Steve Davis [00:07:47] Why do you think, you know, with all the standards work being done, why do you think some companies or industry are still using, I guess just the same materials that they've been using for years that really ultimately don't have the same durability as some of the materials that are out there today?


Len Allison [00:08:01] Yeah, I'm glad you asked. I think it has to do with the difficulty in a company to change, all right. Say a company like yours, you've been printing for quite some time. You have a lot of processes setup around a particular material set. And if somebody comes in with the new material set and says, "hey, you should use this," that's quite a leap of faith for a company like ours to go ahead and make that change unless there's a significant advantage in it. And some of the people are just pretty comfortable with what they're getting right now with very old materials, but they use them according to these old ASTM specs that are, you know, like kids glove exercise if you don't mind me say. And so we don't, in my opinion, gain market share against copper circuitry via them. So it's just a matter of us continually setting the bar a little bit higher by which to attract more customers to this kind of technology. 


Steve Davis [00:09:06] Yeah I'd say the only thing I would add to that would be, you know, sometimes customers change control processes can be a hurdle, too. You know, it's like the customers, you know, they want to change, but at the same time, they don't want to change because change is hard, especially in high compliance markets. So I know that what we deal with, you know, some limitations there. You're in a high compliance, whether it's medical or aerospace or some high compliance industry that, you know, it has to be a pretty compelling case to route a whole change control process through building material, retest everything. So I know that that's probably a hurdle, too. I mean, I don't know if you want to comment on anything from that nature. Do you run into that to where the, sometimes the the OEM or the brand owner can be their own worst enemy, where the innovation is right in front of them, but they can't go out and grab it because of the compliance hurdles just to change, right? 


Len Allison [00:09:54] Yeah, just, just to change like that. Well, yeah. Compliance is part of it. Now, I hope I answer your question the right way. But for us, when we demo this, we're typically demoing this to what we would call your customer, like an Apple, or Amazon, or Google, or Becton Dickinson, Medtronics, those kind of people. 


Len Allison [00:10:17] And if they look at that and say, yeah, that's kind of performance I need, I'm not getting that today. Well, hopefully they're going to specify this kind of performance characteristic into the circuitry that they're asking for. And at that point in time, you know, especially, you know, adding the functionality of printed resistors, LEDs, capacitors, maybe even IC Chip, and to have those be able to put up with a lot of significant abuse like that. You know, people get excited about that. 


Len Allison [00:10:46] So at that point in time, that customer is asking you, the printer, to print that material like this. Yeah okay, that's a good scenario. To replace business that's already in place. Harder to do. And with you folks, you've got a building material set that you've been printing for maybe 20, 30 years on some long running projects. Now you're going to have to have a whole new different set of materials on your shelves. It's a bit of a challenge. 


Steve Davis [00:11:14] And when I started the podcast, I talked about how, you know, you've gotten me to go up in the blimp and look down on this thing called flexible print electronics. And obviously, you know, us laying down conductive pastes. We're only one sliver of a great many serving, I guess, the needs of brand owners and flexible electronics. So what really is, I guess, if the durability can increase on in these types of products, what does that mean then for, I guess, the larger pie of other applications that are out there that people are using a copper etched, you know, flex circuit, you know, are we now looking at an infringement or just a larger opportunity for design owners to, I guess, increase sales or reduce costs with a new technology that's now more durable than it used to be? 


Len Allison [00:11:58] I'll start with one of the things about this kind of circuitry that's a lot, one of the bigger advantages is the film that it goes on. This kind of film is much cheaper than kapton film or the  polyimide film that's used in copper flex circuitry. Also, this is all additive. So you're not etching away stuff, so you're not putting valuable materials on there in etching it away. So this is all additive. The advantages of copper is that it's pure metal. So it's very conductive. So there are some things about signal attenuation and so forth that we're always going to be fighting. The ability to attach IC chips very readily and quickly. It's hard to beat solder in a case like that. So those are some of the biggest challenges that remain here. But for us to be able to make something like this low cost, attach smaller components like LEDs, resistors, capacitors, and then maybe integrate in a copper flex circuitry with the IC chip and so forth, that's quite popular. I can name a few examples of where we have replaced copper in applications where, for instance, 30 years ago most people said, "no, I can't use this kind of material in an automotive application because, there's things called glass transition temperatures, and in the heat of the car and so forth." But today they've proven that these do work in a car. They work inside the passenger area quite well. There's plenty of seat sensors, occupancy sensors or seat heaters. There's a lot of growing applications for touch applications within the car that are expanding on that. So that's one application that has gone from copper over to polymer thick film circuitry. 


Steve Davis [00:13:53] Let me jump in, because for those who are I guess, are listening and not looking, Len's been holding up a EMS PET film with I guess demonstrative technologies on the film. And that's obviously some type of give away, or marketing promotional item that you can put in front of a brand owner or design engineer, right? Because I feel like it's kind of like that Steve Jobs thing, it's like our customers don't know what they want until we show them. And so how do you get the word out or get things in front of design engineers or buying or product teams to have them really see for their own eyes and demonstrate, you know, the functionality of what you clearly are able to demonstrate and get out in their hands. I mean, that's obviously a promotional item. Are there any, I guess, tactics or ways that you've used, that being one of them, in which you can go out and actually demonstrate the feasibility of some of these more durable printed electronics applications? 


Len Allison [00:14:48] Right. Yeah, I can tell a short story about. One of the biggest white goods manufacturer, appliance manufacturers in the world. 


Len Allison [00:14:59] Were having their washing machine, dishwashers, etc.. 


Len Allison [00:15:07] switches made using PTF ink circuitry, and they were attaching components and so forth to it. They got to the point where they were pushed for lower costs, so they were doing these off shore. And if you don't do a surface mount joint right and use the right kind of materials, you're certainly not going to get the kind of durability that I was just demonstrating. And so a big company like that, they'd get some field failures and they say, "see that polymer thick film circuitry doesn't work that well." And so they went running back to copper circuitry and so forth, and it didn't need to happen. They just needed to either use the right materials or, you know, pay attention to the designs and so forth. So the company that this happened to eventually several years later did come back to polymer thick film circuitry with surface mount attached components and so forth. But it took some time. So what happens a lot for us, someday somebody wakes up and they say, "hey, I'm going to do some surface mount attachment to these circuits of mine." If they don't do it right, they can get failure, and if they get failure, they can give the whole industry a bad name. So it's that level of durability that, we didn't even have at that time a test for surface mount devices that showed a mandrel test, all right? So we finally did put this mandrel test into place, and now so we have something that says, you know, if you really want to make sure your surface mount devices are robust and rugged, and to the quality that you want, here's an ASTM test that you can run to, to prove that to yourself. 


Steve Davis [00:16:51] Yeah, it's funny how you know, all these different moving parts between, you know, whoever's innovating the materials, the contract manufacturer that might bring the components together, and then the testing standards that need to be there. I mean, not much changed, I'm assuming not much changed in the technology of this particular, this brand owner waited a period of time, revisited it two to three years later, not much probably changed on the material side, but what wasn't clear in the beginning was, you know, the test standard or maybe the right partners weren't in the room. And then assumptions are made and you walk away from a potential design, and I want to come back to the, I guess, the value of the PTF versus the flex circuit. They missed an opportunity to reduce cost, more environmentally sustainable process. There's other benefits, but can you point specifically, I guess, to distinct benefits of the PTF circuit versus a copper etched flex circuit? 


Len Allison [00:17:44] Yeah. Again, you know, the substrate is a much lower cost, the inks are done in an additive way. So you print just what you need. You can add a lot more functionality with conductive ink circuitry because we have silver, we have carbon inks, we have copper, we have zinc inks, we have nickel inks, dielectrics, silver chloride for medical applications. So you can build a lot more functionality. It's not just copper. So all of these things can be easily printed and integrated into that same circuitry level. So that's the biggest advantage of this. 


Steve Davis [00:18:24] Back to the test data on the ASTM or IPC standards, those, where, I guess where do you think that's at? Are we all the way to the point now where this stuff is publicly available? People just need to know where to find it? Or is there still a body of work that still needs to be done to truly, I guess, bring this into the realm of, "hey, we've really got something here that's more durable," and really trying to, I'll say, take market share from a traditional flex circuit. 


Len Allison [00:18:49] Well, let's take a couple of examples. The crease test, for instance, right? The ASTM test that's been setup for this, because, and why do they do it in the first place? Okay, sometimes you'll have a circuit with the long tail on it, and that tail has to be bent or folded under like a computer keyboard or something like that. And sometimes it can be pinched and have a sharp crease. Well, the ASTM tests for inks dictate one, yeah one compressive crease with a certain pound weight on it and so forth, and that's it. Then you test it. Now, when somebody looks at that, they say "just one?" You know, I mean, can't you do it like two times or three, and a very good rugged test is not only to do it compressive, but to follow that up with an extensive crease. 


Len Allison [00:19:41] And if he can do that 10 or 15 times without the ink cracking, or your dielectric cracking, you know you got a good rugged dielectric silver combination. 


Steve Davis [00:19:50] And that dielectric strength is pretty much verified in that high pot voltage test after the fact. 


Len Allison [00:19:54] So here we still have this crease test, and because I was involved in writing it in the first place, I'm involved now in trying to say, you know, we have to put this to a higher standard. Well, it's got to be a standard that a lot of people are comfortable with. Meaning, you know, are they comfortable with what they've been doing as a legacy product that's 30 years old, is that going to pass that? Maybe not, so there is some, there is some opposition to it, you know, there's some fear of it. In the same way, I asked the whole group of people that were, it was a SGIA meeting. I said, why, you know, we just came up with this new mandrel test for surface mounting. And some people already did this. I mean, they did that. But there were some tests. So I asked the group why why wasn't there a test? And most people kind of looked at their shoes when I said, "it's because we didn't, we weren't comfortable with doing that test because you didn't think you could make things work robustly." And that was really the answer. That that's why that test wasn't in place, but now the test is in place, and I think it's very important that the whole industry make these a lot more durable so that we can capture more of that copper market, which is much bigger than polymer thick film circuitry circuits like this. 


Steve Davis [00:21:11] Yeah, I guess, question where, this isn't really in line with durability. When I think of like, this is generally a low current applicator, I mean this is usually a low current family right? And I'm just curious, does this bring implications where maybe that could be challenged also where you start getting into maybe higher current applications because of all the increase in durability, the ability to just, I guess, just enter into even more a market share of a traditional flex circuit by challenging what we would normally think of as low current, maybe going higher current? 


Len Allison [00:21:43] Well, yeah, going to higher current there, there's different ways to do this. There are people that can run higher currents, but there has to be heat sinks and so forth. The common failure with this kind of material, these are thermal plastic materials. It's a thermal plastic film. Thermal plastic inks on it. And if there's a hotspot, it'll burn and melt that at that point of a hotspot. Now, that hot spot could be because of a print imperfection. It could be because of bad design. It could be because of an overload. But yeah, that's something that we have to be careful of. 


Len Allison [00:22:20] And so there are, there are ways to have a heat sink in place that's going to greatly reduce the chance of a burnout. And there are, their kind of substrates are a bit more expensive, that would also help with that because again, a big portion of the failure is the ink getting hot, and the film and the ink together at that junction melting, so. 


Steve Davis [00:22:48] What about humidity? We haven't talked about humidity resistance. Is there anything, I guess, new, up and coming, or that you guys have already figured out on the material side that kind of raises the levels of humidity resistance? If I bundle all that in to durable. 


Len Allison [00:23:02] I'm glad you ask because I didn't talk about that yet. Okay, so if you look at the humidity test for copper circuitry, there usually at 85-85, which means 85% relative humidity, 85 degrees C, damp heat chamber, with a voltage bias across the leads and so forth. And they look for a short or whatever with the voltage bias. If you look at the test standard for conductive ink circuitry, which was written quite a long time ago, it's, I don't have the numbers right off the top of my head. It was something like a 40 degrees C test with much less humidity, and with a much lower bias voltage. Now, I don't think that needs to be that weight either anymore. We test all of this at 85-85, which is a standard that's used for solar panels, for instance, right, so that's pretty severe. And we put a 5 volt DC bias load across it, and we're looking for any kind of a failure in a cross socket. It's really a matter of testing that insulator more than anything, but also there's some things to do with ink. But it's testing the insulator to be able to protect opposing layers like cross over layers of conductive materials. With that kind of voltage put across it, putting it in very severe heat and humidity situation. So that's another test that I think could be a lot more severe. I think it should be, because if we can say "here's some circuitry, if you use it like this with these kind of materials, you can get 85-85 performance out of that, just like with your copper circuitry." 


Steve Davis [00:24:54] Now it's amazing, I mean it's amazing how the technology's continuing to evolve and correct me if I'm wrong. I'm trying to get my thoughts on this one, but also the connector, like the, is it the zif tail connector. And you talked about mismatch of, we talk about compatibility between materials where I think it's like a copper on the silver. Can you just speak, I guess a little bit to where there's been some confusion maybe in the, I guess, the proper design of a circuit and what's kind of, what's been being done versus what could be done, and how that manifests itself in durability issues.


Len Allison [00:25:27] Right, right. Yeah, when we we start talking about that, the size of the polymer thick film market being what it is. There aren't many connectors that were designed specifically for it. Zif connectors are kind of popular for as easy it is to put them on, but they were designed for copper circuits. They have very sharp tines sort of made to dig into the copper, get past the copper oxide layer. So if you have something like that and you put it into a polymer thick film tail, you can, you can score through it if you're not careful. A lot of people, after trying to use those for years, they'll go back to crimp on connectors or a flat blade type of connector system that the zif connector. But we can put, you know, like carbon inks or our nickel ink on top of the silver, and that helps to protect it from the scoring of that, of those sharp tines of the zif connector. But again, it gets down to that the market size of membrane switch versus copper circuitry, are they going to make a connector specific to membrane switch? Typically not. 


Steve Davis [00:26:42] Yeah, well, you know, with a lot of the things we've been talking about in the expansion of durability, I think there will probably going to be a little bit more attention, you know, with printed sensors, and flexibility sensors, and product teams wanting to just add more functionality into their designs. I think, I think it's inevitable, to be honest with you, so. Well, listen, sure, one more point because I think we've got a few more minutes. 


Len Allison [00:27:03] One more point to that. Surface mounting, you know, to have a system that can rapidly and accurately put down much finer surface mount dye, you know, it's going to lead to that durability. Now if I had a surface mount LED that was about half the size, I mean twice the size of these, or, you know, an inch by an inch, call it, you know, if I tried do this mandrel test, yeah, there would be a lot of stress and strain on that. But putting on a much smaller SMD dye with equipment that was originally designed for the copper circuitry market, meaning there's a lot of whistles and bells on it, it's very well done. I'm very excited about it because it's a jet dispense system, and the jets dispense conductive adhesives, and under fills, etc, are very accurately placed. So I'm very happy about that. If there's any topography in the film or the platen and so forth, that doesn't matter because you're spitting the film or jet dispensing this adhesive across the distance so you can make much finer dots for much finer surface mount dye, and in a much more rapid fashion. So some of this newer equipment will dispense, jet dispense several materials at once, and then pick and place under the same machine hood all at once in very rapid fashion. And then, you know, so what you're doing, very accurately placing a lot of LEDs, resistors, etc. maybe diodes, etc, in a real rapid fashion. And so we have adopted our materials to work with this equipment that was originally made for copper, and it's doing some excellent things for very durable surface mount devices on PTF circuitry. 

Flexible Printed Electronics - Tapecon


Steve Davis [00:29:03] No, that's great. Thanks for sharing that exciting stuff. It's nice to see, I guess the PTF small industry that I guess it is right now, starting to really, I guess, adapt itself to I guess the larger flex circuit industry, and with the improved durability and all the other bells and whistles that you were talking about. So, Len, thanks for being guest number one on episode number one, and I really appreciate the time and the conversation, so thanks so much, and I guess for those on the podcast, thanks for listening. You're listening to the Better Products Podcast. Thank you. 


Len Allison [00:29:38] Thank you. Appreciate it. 

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