OnTrack: The PCB Design Podcast

The rise in flex applications across all industries from medical to automotive, aerospace and military uses means more opportunity for material suppliers to innovate and meet demand. Here what industry expert Chris Hunrath has to share, from general guidelines for designing circuits unique for flex and materials that can be autoclaved over and over. Listen in to this week’s OnTrack expert to learn about flex and material sets.

 

Show Highlights:

• Medical applications (i.e. instruments for surgery), automotive, aerospace, military
• Foils - as you go thicker, its harder to make electrodeposited. More bend cycles out of rolled and yield
• General Guidelines for designing circuits unique for flex:
  • In general, avoid circuits making turns or bends in bend/flex area - don’t make the circuits go in different directions there and also avoid plated holes in those areas.
  • From a stackup standpoint, balance the construction. Thinner is usually better.
  • Look for opportunities for cracking at the bend point.
• Cross hatch ground planes have multiple advantages.
• Pyralux HT, DuPont - new product with unbelievable thermal performance. A continuous operating temperature. Imagine a flex circuit that can be autoclaved over and over.
• We are a material sciences company. There are really unique ways to put these building blocks together.

Links and Resources:

Pyralux HT

See all the show notes

 

Hi everyone this is Judy Warner with the Altium OnTrack Podcast. Thanks again for joining us. Today we have another incredible subject matter expert that you'll be familiar with because we've had him here before, which is Chris Hunrath from Insulectro and we're going to talk about flex and material sets and all kinds of really great things. So hang tight for that. Before we get going please, I invite you to connect with me on LinkedIn, I share a lot of things there for designers and engineers and on Twitter I'm @AltiumJudy and Altium is on Facebook, Twitter and LinkedIn. Today Chris has some Show and Tell and so I encourage you if you - Chris will take time to describe what he's showing, but if you want to see it, feel free to go to our YouTube channel at Altium, click under videos and you'll see all our podcasts there. And you can click on this podcast and then you'll be able to visually see the materials and things that Chris is referring to today - and that's always available by the way - on YouTube so we record simultaneously in video and in audio so just know that's always an opportunity there for you.

So Chris, welcome back, thank you.

Thanks, Hi.

Thanks for joining again.

So at the end of last time's podcast, we were talking about the rise in flex applications and sort of the increasing amount of business actually Insulectro's doing around flex materials, new materials are going out so I really wanted to take this opportunity to learn about what is driving this uptick in flex, what applications are driving it  , what the cost, performance implications of that is, and so let's just start with what is driving this uptick in flex?

So a lot of it's medical, you know, and the way electronics are finding their way into medical applications. Actually it's everything, it's automotive, it's aerospace military - military has always been a big user of flex, but of course you know, all the new inventions that are used in medical applications - certainly some devices are implantable and that's something that's not new, but then we're seeing a lot of applications where instruments are being created that are used, for surgeries and things and they use flex circuits and that's because you can make things very small which is always an advantage when  it comes those applications and we're even seeing some applications where the products are reused. They're being sterilized, autoclaved, what have you and then they're being reused. But lots of new techniques, lots of new devices being developed using flex. Most people are familiar with traditional flex applications like your laptop screen, very often the interconnect between the main system and the screen is a flex circuit. You know the old flip phones all had flex circuits, your inkjet printers had a dynamic flex circuit between the printhead and the actual motherboard and the printer, and actually that's something I do want to point out is, you know we describe flex applications in two main buckets. One is dynamic flex and the other is the flex to install and it's just exactly what it sounds like is flex to install. Typically you're only bending the circuit once or twice to fit it in whatever it needs to go into and then that's it. Whereas dynamic flex, the part’s flexed in use many, many, many times.

I think that something that most people can relate to because you can see it, is the flex inside copy machines right, you can see that dynamic flex moving again and again and so are the materials - the entire circuitry is rated to have X amount of dynamic motions for the life of, it or how does that work?

Yeah actually that's a pretty good point and that can become very complex. A lot of it has to do with layer count, the base material. You know the most popular base material for flex circuits in reflow assembled PCB - a little different than printed electronics applications - where you're using conductive adhesive, but if you're doing reflow assembly, the most common material's polyimide film, and one of the most common materials is Kapton, but the thickness of the materials, the type of copper circuitry, the thickness of the copper foil - all those - play into a number of bend cycles even the type of copper, whether you use rolled annealed, which is very common in Flex, versus electron deposited-

Okay

-well that can get very complex. There are some good design guidelines out there by IPC and others you know. Again I always shout out to the board shops, some of them have good teams that help people   choose the right construction, right stack up to get the most bend cycles out of the device.

Are those the two most common types of copper used in flex by the way Chris? Is a rolled anneal an electroless?

Oh it's electro- deposited.

I'm sorry electro-deposited okay.

Yeah - and yes but unless you're dealing with very thin foils rolled annealed is the most common. That's what we call 'RA foils' the most common. Actually I have a sample here. This is some Pyralux clad. You can't see the dielectric inside, but it's got rolled annealed copper on both sides and it can vary from - you used to be limited to half ounce or 18 micron and thicker so a little side note on foils: as you go thicker it's harder to make electro positive foils because it's more plating time on the drum. With rolled annealed it's the opposite, thinner foils are harder to manufacture because you need more rolling processes to make the foil thinner and thinner and thinner.

I see.

You used to be limited to 18 micron or half ounce, now we can get rolled annealed coppers thinner, down to 9 micron or quarter ounce. You can get a rolled annealed, but the structure is much better for flexing because the grain boundaries are in this direction platelet-type, overlapping grain boundaries which is better for bending. Any foil boundaries are like this and if you bend it you can cleave the grain boundaries in. You get more but it's not that easy - foil doesn't work and flex but you typically get more bend cycles out of rolled annealed.

Okay very good. That's something actually I didn't know and it's something I've talked to my friend Tara Dunn, who's in flex - and it's just something that's never come up so I think that's kind of an interesting point. So, you mentioned with military applications - because my background - military was always SWaP right, Size, Weight and Power - so are those the same type of things that drive the other applications - obviously in smaller spaces - we can fold things up on themselves and get them into smaller packaging. When you talk about the dynamic, what other kind of things sort of drive the desire and the fit for flex?

So something that's applicable to both military and medical, is you want to reduce the size, so I have here - this is a 50-ohm SMA coax right. It's basically one circuit, you've got the shield layer, the shielding around the center conductor - but this is one channel or one circuit and I have here flex, and you can see how many circuits you have on this piece. So, imagine if you had to have one of these - for each one of these-

For each channel right.

Now if you - depending on the design, whether it's strip line, micro strip, and whether or not you have   in-plane shielding, it might be every other one's a signal. But still the weight and size is the difference between having cables right, which I'm holding up right now, versus having a flex circuit is huge right.

And in the case of medical, some of those traces can be as narrow as 20 micron. So you can fit a lot of circuitry into a very small space. And you know depending on the on the medical device. We see some of our customers will build circuits that are very, very long and very, very narrow, and you can imagine how they're used in surgery and other medical applications. And you might have twenty circuits on that part but it's in a very, very, very small space.

Oh that totally makes sense.

Now - just to be clear 20 micron circuitry - it’s not easy to do, it's doable, not easy to do, but certainly 50 microns is, most board shops can do that these days and  again you can fit a lot of circuits in a small space and of course they can flex, they can bend. But in the case of rigid flex where you have a rigid part and bridged with a flex part - and here's another example where you have this -  is not necessarily rigid flex but you'd have components here and then a connector here. You're replacing all these cables right, of this section, so that's how it drives weight and space and even reliability. Fewer interconnections tend to be more reliable so that really helps. So flex has been growing quite a bit for us, for our business and so, a lot of its based on DuPont Kapton and DuPont Pyralux products and then they - there's a B-stage system for laminating the different layers and of course the core, or the clad material as the foil on both sides and then our customers will print and etch to whatever pattern they need and put those layers together as building blocks.

Right so let's talk a little bit about design for flex since most folks listening here will be engineers or layout folks. What are some things that people need to keep in mind about designing these kind of circuits that's sort of unique to flex?

So there's a couple of good - again some good guides out there - both by IPC, DuPont has flex manuals, for different types of categories. Whether it's multi-layer, single sided, double-sided flex, they have some good guidelines on that, but in general what you want to avoid is you don't want circuits to make turns or bends in the bend area. So, for example, I'm going to use this one is an example again.

Okay.

If this is the flex area in this middle section here, you wouldn't have the circuits go in different directions in that area, so you might want to keep them. You want to keep them basically parallel in that area and you also don't want plated through holes in those areas. Again these are just real general rule - basic guidelines. The other thing you want to avoid is what we call an I-beam effect, where you have circuits directly above each other with a dielectric in between. You want to stagger them. That helps, again - more important for dynamic flex than bended, to install, but it's important not to have the I-beam effect because that could lead to cracks...

That makes sense.

-concentrates on bending. And in general from a stack up standpoint, you want to try and balance the construction. Thinner is typically better. There's again - there's all kinds of iterations there's - if it's a multi-layer flex - there's loose leaf constructions where you wouldn't necessarily bond the different layers together in the flex or bend region. You'd have them not connected. A bookbinder system is another way to do it where depending on the direction of the bend, the layers that are on the outside of the bend are actually longer. The layers on the inside - and again the fabricators that are skilled in that know how to space that - and to change the length of the circuit. But you know from a simpler standpoint, or from a more general standpoint thinner is typically better balanced. Balanced constructions are typically better   for flex.

Well balanced construction is always a good idea, I'm just saying but I could see that right. Because I think you - what you're saying if I'm hearing you right, is you have to look for those opportunities for cracking right, or stressing at the bend radius, because that makes sense right. Just from a physics standpoint it makes sense that things would want to give or pull right?

Right, when you bend a flex circuit the other side compresses against it right, and every circuit will fail at some point. It's a matter of how many cycles you get out of it before it fails.

Right how do you measure those cycles by the way?

Well there are some standardized tests and there's an MIT bend test - there's some other testing that's done to see how a particular material, or even a design or stack up performs where it's bent repeatedly until you get failure. And then you can - you can rate the stack up or the and/or the material.

Where can you get that data? You mentioned IPC as a source. Is there any other thing - resources you could share - that I could share with the listeners where they could maybe look at some of these readings?

Yeah actually so DuPont's website, the Pyralux website, has some data on that and certainly some of the folks there could put your listeners in touch with some of the design guidelines.

Okay alright I know some folks there if you and I can't find him through the website then Jonathan just came in to talk at IPC designers Council Orange County I'll reach out to him see if...

Oh Jonathan Weldon, yeah he's a great resource for that. So speaking of Jonathan Weldon, he's been working with HDPUG; they've been looking at shield layers or for reference planes and they've been looking at the difference in solid planes and cross hatch systems, and so this is just a simple - this is actually a simple test circuit microstrip construction where you have a reference plane on one side and your tracer on the other. Imagine if there were a strip line construction and you had copper on both sides with your transmission line in the middle, one of the challenges with all PCBs, and especially with flex, is absorption of moisture and then that moisture released during assembly causing delamination and one of the things that you can do to mitigate that is to bake the parts. Well if you have soft solid copper areas - baking does not work as well - because the moisture has got to go around the copper it can't go through it.

Right.

So cross hatch ground planes are great for two purposes. One is, it's a moisture egress for baking, the other advantage is it's actually better for flexibility it makes the part more flexible.

Hmm, that makes sense.

The downside is the high frequency applications - you can run into some issues.

Yeah.

So and one of the interesting things that Jonathan and company, they were looking at, was the difference between a round opening and a - what's typically used as it's..

Kind of a diamond shape?

Exactly, exactly and really it's more of  a square turned on its side, but yeah the diamond shape versus the you know... It's funny how a circuit design is always in orthogonal patterns but that's not necessarily the best way to go and anyway the round shape was better for signal performance.

Oh, for the high speed applications?

Yeah it makes sense because if you took a circle that fit inside a square you actually have less open area so...

This is true okay, alright.

Yeah, so there's some interesting data on that but I would recommend to a customer, depending on their   their frequency bandwidth bit rate, depending on what kind of design it is, that they would look at using an open plane. It works basically with a screen, for lack of better words, versus a solid plane because the reliability goes way up.

Okay now you just made me think of something. Last time we talked, we were talking about prepregs and glass, being reinforced right. When you're using adhesive systems for flex, I'm assuming they're non-reinforced?

Right.

It's a more stable material though so tell us a little bit about that, about the stability, the dimensional stability?

Yeah so - so really in flex circuits the Kapton film, a polyImide film, because it's a thermoset, it is acting like the fiberglass in your flex circuit.

Okay.

You don't have skew issues because there's no glass, so you don't have micro-DK effects. Now if you do have a crosshatch plane, you will have a different - you'll have a micro impedance effect if you would. But that usually doesn't change with differential pairs unless - again depending on where you put the traces - but you don't have the fiberglass micro-DK effect at all. Now, Kapton's interesting - it's very thermally stable but it's not as mechanically strong as glass reinforced laminate. So it tends to change more from mechanical distortion than it does for thermal. It's not shrinking like epoxies do when they cure. Certainly when you - when you remove all the copper (and I actually have a piece here) this is a piece of Pyralux AP, with all the copper etched off. This is 100 percent polyimide, used to have copper cladding on it and the copper's been mostly etched off. You can see a little bit of copper left  from the tape I use to run this through an etcher, but the material is pretty strong but it can distort mechanically, more so than thermally. So again this is kind of like the fiberglass in a regular PCB, and then you'd have B-stages of some sort, to put all the layers together.

So the actual substrate is creating the stability in the case of flex? Okay that makes sense.

It's a polyimide film, in the case of Pyralux, which is a DuPont branded flex material it's based on Kapton film.

Okay so we talked about ground planes, we talked about where to not put - - is there any other sort of design for flex things that you'd want to mention that are just rather commonplace?

Yeah so there's a lot of things, for example, you could use a pad that's a little bit larger than you would normally use that would go underneath the cover. Now let me backup a little bit and talk about cover lay. So what cover lay is, it's basically Kapton adhesive laminate, that is the flexible equivalent of solder mask. Now unlike solder mask which is used in PCB, which is photoimageable, cover lay has to be mechanically formed and then laminated over the circuitry. So you have openings and this - again this is a another good example - you have openings in the cover lay I don't know if you can see that on this? But there's openings on the cover lay for each individual pad and then that's laminated over. One of the ways to get more reliability out of the pads is to make the pad a little bit bigger than the opening in the cover lay. So you have cover lay over the perimeter of the pad - it's kind of like what we call solder mask defined pad and rigid - except you're doing it in flex, and that's that's one way to get reliability. But there - again there are a lot of different things in flex that you should be aware of, and that's where some of these design guides and things...

Okay well we'll try to track some of those down and put those in the show notes because I think that would be really helpful to have something kind of, tangible. Something I remember learning from someone else, is also talking about tear dropping pads?

Yes. Is that something that you would recommend as well?

Yeah that's good for a couple of different reasons. One is that the more material that goes under the cover lay, again helps mechanically support the pad. It's also important - typically you don't put holes or pads into your bend area, but it could be an area where you could concentrate bending. So in other words, you go from a trace to a pad, that's going to become a concentration of - right at the edge of the pad - concentration of stress and so if you do the teardrop, that distributes that stress over a larger area and helps prevent circuit cracking. But again, you would try and avoid that in your design. We would make that a bend area. And actually, speaking of rigid flex, one of the things that you would typically do is the cover lay would go into the rigid portion only 50 mils.

Okay.

-Okay and then you would keep the cover lay and its adhesive out of the plate through hole areas in the rigid portion and rigid flex - and that's also a 'keep out' region for plated through hole so you wouldn't want plate through holes going through that region. So again a lot of this stuff is spelled out in some of the manuals that you get from DuPont and others.

Alright, I'll reach out to Jonathan and - and you and I can scrounge up some things and we'll make sure to include those here. Last thing I wanted to talk to you about - which I was just stunned by - is that you told me that DuPont has come out with a new material that has unbelievable thermal performance. Can you tell us a little bit about that?

Yeah so - classically in flex, you have your your B-stage, or adhesives that are part of the package, and then you have your core materials, which are your building blocks and you print and etch your core, just like rigid, and you would have - you would put them together with either your rigid or your flex adhesives to make a multi-layer system. What's different about this new product, it's called Pyralux HT, and in fact, I got my Pyralux HT mug here...

Nice, nice.

-but instead of using acrylic or epoxy adhesives to bond the Kapton layers together, you would use this thermoplastic polyimide layer. It's got a very high melting point and thermoplastic's already used in PCB, people familiar with EPI-P and LC, those systems. The only way thermoplastics work in PCB, or reflow assembled PCB, is to have a high melting point otherwise it would melt at assembly. So this is a piece of the thermoplastic polyimide that DuPont manufacturers. It's the HT bonding film. This could either be a cover lay or it could be an adhesive layer to put - to make a multi-layer PCB.

Okay.

-But the nice thing about this, is it has a - 225 Celsius operating temperature, which is very, very high.

What does that convert to in Fahrenheit?

Oh gosh - 225 C it's over 400 degrees Fahrenheit.

I see, 225 - - Fahrenheit okay I wasn't hearing you correctly, so it was Fahrenheit okay.

Oh no - hang on, 225 C, I should know all this without me - - 437 Fahrenheit.

Wow.

So you know, some applications...

-and that's an operating - continuous operating temperature? Which is crazy, cuz some materials can take that heat for a little while but not continuing operating temperature right?

Right, so most PCB materials that go through a reflow assembly, which is either done at 260 Celsius, depending on the type of solder work, or 288 C, they can withstand that for a short period of time most PCB materials survive that. It's the operating temperature most epoxy systems will come in around 130 to 150 C operating temperature - maximum operating temperature.

That's wild, so I'm guessing - so what are the applications where this will be exciting news?

So applications where you had, fiberglass, coax or some other applications like that where you had   wired - high temperature wired connections - or cable connections, you could replace now with a printed circuit board. So engine compartments, aircraft engine compartments, aerospace, down hole, I mean there are a lot of different applications. Even from a medical standpoint. Imagine making a flex circuit that could be auto plated over and over and over again. You don't have to worry what's gonna...

I was gonna ask you about that earlier. I don't really know what temps they autoclave at but you mentioned that before that medical applications could - to cut autoclave to kill the bacteria, but like what's the normal temp of an autoclave, how many times can you do that?

So we have one customer that builds some parts that are autoclaved at 135 C but it's with steam, and it's hard on circuits, it's hard on electronics.

Yeah seems like that would be.

But for HT it wouldn't be any issue because you're nowhere near on the melting point. Now it will absorb some moisture, which could be removed from - could be removed with a bake but a lot of applications it won't matter if the assembly is already done. It doesn't really matter.

Okay.

You know there is some change in the transmission properties of the material when it absorbs some moisture. Again that could be removed with a bake but that is one of the challenges with reusable medical devices, is sterilization and how well the materials hold up, and an HT would be good for that. The downside of HT, is it does require a 600 degree lamination - Fahrenheit.

Okay well there you go, so how many board shops have lam presses that go up to that temp?

So we took a look at our customer base, and it's not a lot of them, or some of our customers had laminate, or have lamination presses that are capable, they're rated that high, but they haven't been turned up that high for a long, long time. So it's funny, some of our customers have started making some HT, all the weaker heaters, that the press might be 10 years old, they turn it up for the first time to a higher temperature; they start popping heaters and they have to go and replace them. But actually we're seeing a trend though. A lot of our customers are buying laminating equipment and right now that's a whole 'nother story because lean times are way out on equipment in general, but what we're seeing is people are making sure they have that high temperature capability and it's not just for something like HT, it's for LCP and FEP as well.

Okay.

They have some good properties, electrical and and signal properties.

They do.

That's a big deal these days.

Performance wise they're very good.

Right they're harder to fabricate but they do have some good properties you know. Even - we talked about last time - repeat glass-reinforced PTFE materials, some of them require high  lamination temperatures.

Yeah they do.

Yeah all right. One more material I do want to mention - sorry - so this material actually is a Teflon Kapton laminate it's called...

-wait hold on - Teflon Kapton? Oh okay.

It's called 'TK' - it's a Pyralux product from DuPont and so it has a core of Kapton to act as the XY stabilizer, but then it has a Teflon material on both sides and again, this is a building block but it's very low loss, and very low DK. So a DK of about two and a half with a very, very low loss. But unlike glass reinforced Teflon systems, this has no fiberglass so, no skew and no detrimental effect from the fiberglass. It's using the Kapton instead, as the stabilizer, because if you had a piece of - I should have brought out a piece of Teflon - but PTFE films you can easily - it can be mechanically stretched.

Yeah, one time when I was in the RF and microwave board space, I had the board shop I was working for take all the materials like Rogers, Taconic, whatever and I had them strip all the copper off and I went   like the 4000 series 6000 series 3000 series all the way up to 58, 80 and strip off the copper. Because when you see them clad, they don't look that different from each other. But I'm like here's Teflon - this is like a piece of rubber, and imagine heating that up, exposing that to aqueous hot processes and so I think that really helped people to understand how vastly different they are and I think it was a good visual actually to help people understand how radically different these are and when you start stripping off all the copper and you have fine lines and all that then it's - it's a whole different animal.

TK material is - the core material is nice because the Kapton layer does provide mechanical strength. Again though, the TK, instead of requiring 600 degree lamination, it requires 550. So it's still a high temperature product which requires the right press book, the right materials, and lamination, and it also requires a press being capable. And the other too is the board shop needs to get accustomed to the dimensional changes during the lamination process with these materials.

Right.

Again - a lot of it's mechanically driven, but you need to know how to work with it so that's something I think the boardshop needs to have experience with.

Well and I imagine that you're not going to see these materials outside of sort of high performance or high speed capable board shops?

That's true...

-I don't know if that's true I guess I'm looking to you for an answer in there but it's an assumption I would make.

Here's the interesting thing about AP, AP by itself, is actually pretty good electrically. It's the adhesive layers you use that incur a lot of the loss. So then if you get into the thermoplastic systems that have better electrical performance, now you're getting into the temperature range. So it's one of those give-and-take situations, but you can mix and match the materials to some degree. You could use, for instance HT bonding film with AP clads, your operating temperature would default to the AP operating temperature, which is still pretty high at 180 °C, but electrically it's pretty good. You get away from the acrylic and the epoxy adhesives, which aren't great electrically, in terms of loss, dielectric constant so yeah, I think as I think as board shops become better equipped with high temperature systems, you'll see a broader use of these materials.

Right, I mean the market is going to drive us there one way or the other right, if there's a demand then the board shops will do what they need to do. One thing - a comment I want to make about that is - I was in one board shop and I was stunned and then just felt like wow I could've had a V8 moment, is they were providing really high speed, high performance circuits to some high-end military stuff, and they had moved completely away from rigid high performance laminates and used multiple layers of flex materials and the performance - and I'm like - oh well that seems like an obvious, but I had no idea that was even happening. Is that something you have seen, where they just use...

Yeah, if you wanted to get rid of skew completely you could use a film based system.

Yeah it was crazy, I mean that makes sense and I'm sure there's some challenges there cuz I could tell they had to rigidize the bottom, or put some kind of carrier or something, because they didn't want it to flex quite that much but they just stacked these film systems on top of each other and I'm like huh, didn't know you could do that but they were clearly doing it on a routine basis so that was interesting.

Yeah I've seen some board designs where you might have 12 cores of Pyralux...

Yeah,right.

-and then use regular rigid prepreg as a bonding system so and the board's not - when it's all done, it's not flexible it's rigid.

It is rigid, but it's a weird - it's weird to see anyway...

I actually have a board here.

Ok let's see it.

Unfortunately it's single sided so it's kind of like a potato chip, but because there's only one layer of copper and one layer of prepreg, but this is actually DuPont's AP product with Isola's tachyon prepreg, and it's a spread glass prepreg. So you have the spread glass prepreg on one side and you've got the Pyralux AP in the other. So you minimize how much glass is in here, which really drops the amount of impact or micro DK effect which would lead to skew and other signal performance issues. So there are lots of different ways you could use the flex materials even in a rigid design.

Yeah I did see that and I was shocked and I - it's something I hadn't heard a lot about. Anyways well, we're about out of time today, again. But thank you so much, every time I talk to you, I feel like I learned so, so much and it's fascinating to me where the industry is going and what's happening with flex and it's exciting it's really an enabler right and these high, high temp products and that so it's a really exciting time to see. We always break through one way or another it's just interesting to see who gets it done. So it's very interesting to see what we're doing with flex.

Oh thank you Judy for  giving us the opportunity to talk about some of the materials we supply but yeah it's - these are all building blocks and, I kind of view it as a material science company in tech...

You are yeah.

-we provide all these different building blocks to meet the need of what the customer needs.

And there is - and there's really unique ways to put those building blocks together so it's fascinating to learn about. Ok so something I didn't ask you last time, but I'm gonna ask you now. Are you a geek or a nerd? [Laughter]

So the best way I heard the two described is the difference between a geek and a nerd is - a geek is the one who gets things done.

Oh interesting okay.

So I would like to think I'm somebody who'd get stuff done, so that would put me in the geek camp but in any case.

Alright check geek, and the second question I have for you: on a scale from one to ten how weird are you?

[Laughter] Oh gosh, I would say - five.

I'm sorry but if we're in this industry we're at least 5 or above. I think we have to be a little wacky to do what we do - okay well thanks I appreciate it so much and again, we were talking on the phone yesterday we have more to cover, so I'm gonna for sure have you back again and talk about printed electronics which is on the rise and you know a lot about. And also I'm very excited to talk about - oh there it is!

Electronics, that's a whole other - whole other world of electronics and yeah.

Wait, wait, wait bring that back and tell our listeners what exactly that is.

So this was printed with a zebra label printer where the - and no changes to the machine by the way - but the special foil is put into the system where you normally put a roller with a pigment film, so instead of printing a black label you're printing metal foil so yeah, it's kind of interesting.

Yes what is that for?

Well this is something did for me at our booth this is just an antenna but you could really you could make electronic designs on the fly now...

Dude, you're still not answering my question here. What is that intended for?

So I'm gonna use that for an antique stereo I have. I have an antique FM stereo the tube, old tube radio, I'm going to use that as an antenna.

I see - oh see definitely five-weird. I say I'm gonna make that matrix instead of the hot crazy matrix I'm gonna make like the geeky-weird matrix and so yeah - you're at least at a five -high and a geek.

But anyway printed electronics is pretty exciting, I mean and again, it's all material science based. As the materials get better you're gonna be able to do more things. Higher conductivity inks, higher temperature inks, I mean there's all kinds of things you can do in that area. Typically the substrates are different - they're typically lower cost, lower temperature capable substrates, but you could - you can make all kinds of things so we'll get it the next time.

Okay we'll definitely do that and the other thing I'm excited to talk to you about - because I know nothing about it - is paste interconnects and you shared a little bit, so anyways we have at least one or two more podcasts ahead of us, so for our listeners; stay tuned and we'll make sure and share everything Chris has talked about today and hook you up with resources through DuPont, HDPUG, IPC, wherever we can find and we'll make sure and share those resources that will help you lay out a better flex and onboard as much information as you can.

So Chris, thanks again, we'll see you next time and we'll tackle another hot topic. Again this has been Judy Warner with the OnTrack Podcast. Thanks for tuning in and thank you to Chris Hunrath from Insulectro, we will see you next time. Until then, always stay on track.