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Fireside Chat: Can Radiation Damage Electronic Components?

If you ever wanted an insider’s view of Fermilab’s Tevatron particle accelerator, there’s no better guide than Creative Electron’s own, Dr. Bill Cardoso.  We got such a peek in this week’s Fireside Chat with the Xperts, as Dr. Cardoso’s time and experience at Fermilab is tapped into when answering the question that was this week’s topic, Can Radiation Damage Electronic Components?  The question is a simple one, as Dr. Cardoso explained, and though the answer is complicated, it is also fascinating.

While a definitive answer to this question is elusive, Dr. Cardoso  provides a guide through the details that can help assess exposure risks across a broad spectrum of electronic components and their uses.  If you missed it, enjoy it and other Fireside Chats with the Xperts here.  Thirty minutes to a bigger brain!

 

Transcript:

David Kruidhof:

Well, it’s 10 o’clock. So let’s go ahead and get started. Welcome everyone to another Fireside Chat with the Experts. I’m pretty excited about this one. We’re going to be covering a topic that we get a lot of questions about, a lot of curiosity from different industries. The question is, can radiation damage my components? So we have Dr. Bill Cardoso here. He’ll be speaking to us, to answer this question. It’s a complicated one, so it’s good we have someone with a PhD here to get into the details of it and explain it to us. So go ahead, Bill.

Dr. Bill Cardoso:

All right. Thanks David. Thanks for the introduction. Good morning, everyone. Thanks for being here with us for another Fireside Chat with the Experts. And yes, the question, we’re going to try to address today is if radiation can damage electronic components. And I’ll let you start with some of the background. That’s where I learned a lot about radiation effects on those electronic components. That was at Fermilab, which is Fermi National Accelerator Laboratory. It’s a particle accelerator right outside Chicago. It’s about 40 miles west of Chicago. Well, 40 miles east of Chicago in the middle of Lake Michigan, so it’s got to be west of Chicago. And at Fermilab, we had a six mile long ring called Tevatron that you can see here in his photograph and the Tevatron was a particle accelerator. So there’s a complex of smaller accelerators. This is the main injector that produces protons and antiprotons that get successively faster and faster.

Dr. Bill Cardoso:

So when you get to the Tevatron, which is this big six mile long ring here, they are flying at very close to the speed of light. And what we do is we, we get them going around the ring in one direction and then we got the antiprotons going in the opposite direction. And so the two clouds of particles, they keep flying over each other. And then in a couple of very specific places, namely the DZero here, and a CDF here, and DZero further down the line, we merged them. So they have a head-on collision. So we have these protons and antiprotons colliding at very fast speeds. And as a result, we have this shower sub-particles and with those sub-particles, we can study quite a few things. The last thing we were looking for at Fermilab was the Higgs boson which, physicists say, explains quite a bit of the dark matter and things that are missing, that we can account for in the universe.

Dr. Bill Cardoso:

So these are some of the things that the group I was part of, did at Fermilab. We designed these cameras that tracked this shower of sub-particles. And as you could imagine, these electronics get subjected to an incredible amount of radiation. Right? And much like satellites, the systems, they have to be built with incredible reliability. Because once you dig this electronics, several floors underground, basically, you can’t maintain them. So if something breaks, it’s going to be broken until the next shutdown, which might take two, three, four years. Right?

Dr. Bill Cardoso:

So radiation damage and radiation effects on electrons was something we took very seriously. And we did a lot of research to understand exactly how radiation would impact the lifespan of the components, the cables, the Kapton tape, everything that we used, printed circuit boards and everything else we used, all those electronics. Because as I said, there was an incredibly high radiation environment and at same time we couldn’t fix them. Right? So to give you an idea, this high definition cameras if you will, was placed right on the beam. So the beam of protons and antiprotons would come through this pipe here. So we built this huge, building size, particle detector. And once it was done, we just roll it into the beam. And several years later, roll it out for upgrades and major maintenance.

Dr. Bill Cardoso:

So the question is simple, right? Is radiation going to damage, my electronics, my components, my whatever. Unfortunately, the answer is quite complicated. It’s not only complicated, it’s also complex. Because, it depends on a lot of things. So in this presentation, we’re not going to answer the question. Okay? If you’re expecting to get a yes or no answer out of this presentation, just go to the next video right now, or go do something else because you’re not going to get a yes or no answer. What we’re going to do today is to build up and explain what are the parameters that are going to lead you to an answer. Right? And we’re more than happy to sit down with you, if you do have questions, contact us. We’re going to give you our contact information at the end of this presentation, so that you can call us and we can work through some of these questions to figure if the electronic component that you’re testing has a chance or not of being damaged by the radiation exposure, you plan to subject that part to.

Dr. Bill Cardoso:

So let’s start from the beginning. Right? From the basics, which is types of radiation. Now, there are two main types of radiation we’re going to be talking about here. Let’s call them rays and particles. Let’s keep it simple, right? Rays and particles. Rays, like photons. The most popular ones are gamma rays and X-rays, that’s what we do for a living. Right? So those are rays, they’re photons. And then you have particles. Stuff that we did at Fermilab, like I described a couple of slides ago, those are all particles, protons, antiprotons. Other accelerators have electrons. And there’s a major difference between a photon, as you can see here on this column, and particles, as you can see, protons and electrons. For example, protons are very heavy, very dense particles. They can’t really travel very fast.

Dr. Bill Cardoso:

Protons, they have quarks, usually have three quarks. It’s a massive particle. It can transform into a gluon. And so, protons can be very complex particles. Electrons on the other hand are point like particles. They’re much simpler. Some accelerators use electrons since they are point like and very easy to study, because the energy that you give to an electron is the energy that’s going to take. Protons, you don’t ever know what state the proton is. So you can’t really, always tell the energy of the proton. Physicists, like to say that colliding protons and antiprotons are like colliding trash cans, while electron colliders are scalpels. Right? They’re very precise, very fine research. And there’s a reason why you do one or the other. Photons, they travel speed of light because they don’t have any mass. Right?

Dr. Bill Cardoso:

As you can see here, protons are heavy compared to electrons. Photons don’t have any mass. That’s a reason why particles have a very intimate and destructive relationship when they collide with matter, while X-rays and gamma rays, they have a different type of interaction they tend to penetrate. Right? I really like to show this representation here, where you can see how alpha particles have a very limited penetration of matter. Usually a piece of paper can stop alpha particles from traveling. And that’s the reason why americium-241, an alpha particle generator, a radio isotope is used in the RS smoke detectors, in your house. What you do is you put a sensor and americium-241 source. And that sensor is always getting radiation. So, okay. The path there is open as soon as smoke goes in between close the path and triggers the alarm.

Dr. Bill Cardoso:

So phenomenal source of detection of smoke. And that’s why you have to replace your smoke detector so often because that americium source has a half-life that eventually doesn’t work anymore. Beta particles, they are electrons. So they’re smaller particles. And as a result they have a better penetrating force. A piece of metal can stop a beta particle with no problem.

Dr. Bill Cardoso:

Gammas and X-rays, on the other hand, they have much better penetration power, and that’s why you use them for inspection, for imaging. Right? X-rays are very good for imaging because we can get them to penetrate through the matter through your component. On the other side, you can create the shadowgram to give us the image or the shadow, a negative image of the component that you’re looking at.

Dr. Bill Cardoso:

So electromagnetic radiation, X-rays and gamma rays. Particles, you have protons, neutrons, electrons, pions and muons and everything. They’re super flatters afterwards of different types of particles that interact with matter.

Dr. Bill Cardoso:

For the most part, damage happens with particles because particles have mass. And when you jam them against your component, they’re going to damage something. Again, at Fermilab our main concern was protons and antiprotons and, soup, so particles that came after those collisions. And they did quite a bit of damage to the components that we installed. And electromagnetic radiation is fairly docile to electronics.

Dr. Bill Cardoso:

So before we get into the exposure from our X-ray machines, let’s talk a bit, what else, or where else your parts, your electronic components are going to be subject to radiation. Starting with background radiation. Right? We’re all subject, to radiation 24/7. The concrete that we use in our construction has radioactive components, radioisotopes that are going to be radiating in the soil, depending on what kind of soil you have, how much granite and some of the other materials on the soil, can give you a higher, lower background radiation. So there are maps online, you can check out, that map the background radiation as a function of geography in United States and other places in the world.

Dr. Bill Cardoso:

Then on top of that, you have cosmic radiation. The atmosphere serves as a shield, right? From cosmic rays that come from stars that implode or galaxies that explode and emit a huge amount of radiation many millions higher than any atomic bomb can produce. And that radiation travels across the universe, and the atmosphere is our shield. Right? So depending on the altitude, you’re going to have more or less of that shield. And as a result, more or less cosmic radiation being subjected to your components. And then on top of that, we have manmade radiation. Right?

Dr. Bill Cardoso:

Including inspection in airports. Every airport you’re going to go through is going to, X-ray your parts, your components, your luggage, everything. Right? Nowadays, you don’t have an option. You’re going to get X-rayed. Even if you don’t know, your components are going to get X-rayed. Ports of entry. Right? As you get in and out of the country, Customs and Border Protection, CBP is going to use very sophisticated and very strong radiation portals to image the containers where your components are going to be shipped. The post office all around the country have X-Ray machines that are constantly inspecting mail as it comes and goes. And same goes for every delivery company out there. FedEx, UPS, DHL, they all have X-ray units to image. And, its ubiquitous. Nothing you can avoid. It’s how the flow of commerce is regulated and protected in the world nowadays.

Dr. Bill Cardoso:

So security, quality assurance, failure analysis, counterfeit detection. Those are all, some of the main applications that require subjecting your components and your parts to radiation.

Dr. Bill Cardoso:

So part of the conversation, now that we have some of the basics of what radiation is, what type of radiations impact components, how different radiations impact electronics. Let’s go over how, and what’s the mechanism of damage. Right? So, when you think about if radiation is going to damage my component, the first thing you’ve got to figure out is what kind of radiation are you subjecting your component to? You, as we said before, particles, are much more destructive than photons, larger particles have a much higher probability that they’re going to damage your component than a lot of smaller particles. Protons against electrons. And finally, if you have photons, it’s a much smaller probability that you’re going to have any damage.

Dr. Bill Cardoso:

Then once you figure out what type of radiation you are considering, the next question you’re going to ask yourself is what energy level are you going to be working at? Right? The more energetic, the radiation, the higher probability that you’re going to damage your component.

Dr. Bill Cardoso:

Once you figured out the type of radiation and how energy are going to be talking about, in X-ray terms, the energy would be 80kV, 100kV, 160kV, 50kV. Right? Watch how much energy those photons or particles are going to have once they collide with your electronics. Then the next is radiation flux, which means it is what is how many of those particles or photons are going to be hitting your component per second. In X-ray lingo, energy is kV. Radiation flux is mA. How big, how much energy the photon has, radiation flux. How many of those photos you have hitting your component or going through your component, every second.

Dr. Bill Cardoso:

And finally, the fourth component, fourth leg of this chair is the exposure time. So what kind of radiation, how big it is, how much of it, and for how long you’re going to be exposing your component.

Dr. Bill Cardoso:

You got to know all these four parameters before we even started talking, if you’re going to have damage, or not. And when you talk about damage, there are three mechanisms of damage on electronics. Right? You start in with the bulk damage. Bulk damage is serious, is very serious. We’re going to start with the most serious to the least serious. Okay? The big one is bulk damage. Bulk damage is when you can transfer enough energy to the silicon atom, that you can remove it from the crystal lattice. Right? So if you can do that, if you have enough energy to impact the crystal lattice, your silicon components is done.

Dr. Bill Cardoso:

And I don’t know of any X-ray spectrum system in the market, X-ray inspectors to the market, that has enough energy, that’s capable of applying bulk damage to electrical components. So bulk damage is very common when you’re talking in particle accelerators with particles, if they are, the Gig electron volt. We do kilo volt, right? Which is thousands of volts. Gigavolt, it’s millions of volts. That’s when we start talking about bulk damage. And again, in particle accelerators, what you do is you figure out how much radiation your components is capable of taking before it gets damaged. And you just figured out how long, what’s the life span or expected lifespan of the component. So if you figure out electronics can survive five years, and your experiment is expected to run for two years, said, “Okay, we’re fine”. Because, this is likely going to die after our experiment is scheduled to be over.

Dr. Bill Cardoso:

Surface damage on the other hand, as the name suggests, is when you have ionized radiation going through the silicon oxide, you basically build up, over time, enough charge to change the characteristics of the silicon oxide, very common to change threshold of transistors. Right?

Dr. Bill Cardoso:

So what happens over time, very common what you see, over time, you have enough electron-hole pairs created on the base of a transistor. And what you do is you change the threshold. So as time goes by all of a sudden, some of the transistors in your memory, for example, stop working, right? Because now the threshold is here and you’re putting your signal here. Your threshold started here, on/off was here, everything was working beautiful, electron/holes, accumulate. Your signal is here, threshold is there. Before you know, a section of your transistors don’t work anymore. It’s a pain in the neck. And it’s destructive. Once it’s done, it’s done.

Dr. Bill Cardoso:

The last one it’s called SEU single event upset. Single event upset, very common in satellite applications and also particle detectors. This is one, when a radiation, a particle has enough energy to flip the state of a transistor, for example. Right? That’s called a single event upset. So what happens is you have, going back to the base of that transistor we were talking about, you set it to a flip and you have enough radiation deposit energy on the base of the transistor to make it to a flop. So instead of flip, you flop, and you can flip the state of that specific transistor. Now, usually your single event upset is a recoverable defect. In other words, if you just overwrite again, that transistor goes back to its initial or correct state.

Dr. Bill Cardoso:

And one of the standard ways you deal with this problem is to use triple model redundancy. So that means that instead of putting one transistor, you put three transistors in very critical locations, meaning that you always take the results of two out of three. So you have a voting system for each flip flop. So if one gets flipped, one gets upset, the other two can give you the right result. Right? So the probability that three or two will be flipped at a time, is extremely low. And you measure, calculate the probability, that’s going to allow you to figure out where are you going to put those transistors? And with triple model redundancy, you can really mitigate single event upset.

Dr. Bill Cardoso:

So the point here is that radiation is everywhere and your components are going to be exposed to quite a bit of radiation, in a daily basis, if you want it or not. Mariem Ortiz are VP of manufacturing, gave a real nice presentation where she went over safety of X-ray systems. And she went over some of these units mR/hr. So I highly recommend you go check her presentation. If you need some clarity, what mR/hr means and how much radiation the FDA recommends or sets as a limit for safety in the country.

Dr. Bill Cardoso:

We are bombarded by a soup of particles and photons in a daily basis. And at cruise altitude, like you were saying, on this plane you’re going to be subject to about 0.6 mR/hr of radiation. One interesting experiment I’ve done a few times, get yourself a radiation detector, a Geiger counter and bring it on the next flight. And you’ll be able to see it changes as you take off and you cruise at 35,000 feet.

Dr. Bill Cardoso:

So as we said before, any type of cargo is going to be inspected with not only kilovolts, but sometimes mega-electron volts, right? So meg in millions and then giga in billions. So kilovolts thousands, mega volts or MeV, you’re going to be in the millions and then giga-electron-volts are going to be in the billions. So a lot of the cargo scanners are six MeV or nine MeV. So millions of volts not kilovolts like we do. So it’s not uncommon to have that specific component that you’re really concerned about putting your X-Ray machine is already being inspected, by a bunch of, of radiation generating device that you don’t even know. Right? So you got to be very careful about that.

Dr. Bill Cardoso:

And it’s very easy, that exposure of all these devices combined, can accumulate to hundreds and hundreds or even thousands of mR. The device we use for counterfeit detection, which is failure analysis, and counterfeit detection, that’s mainly where we use our X-ray machines for, in the component arena. They’re going to be between 80 and 160kv, you don’t really need more than 160kv, to look at a electronic component. And we’re looking at exposure times even lower than 200 milliseconds at a time, depending on the component you have. So, if you’re running your component, imagine you’re going to be looking at component for a second or less at 180kv, you’re going to be looking at 35 mR, for a total dose. Right? For that specific component. So in the big scheme of things, based on all the numbers I’ve given you before, this is very little radiation. Right? We’ve got to agree with that.

Dr. Bill Cardoso:

So based on those parameters that I gave before. Right? Type of radiation, the energy, flux and the time, you want to minimize all those four parameters, should give you the least amount of radiation possible exposure on your components. So what you do is, you automate your system and that’s why we’ve been very successful at offering our customers fully automated X-ray inspection systems, because you expose each component at the least amount of time possible with the least amount of radiation possible. And your let a computer vision program makes some of the decisions. So you don’t have to have a human being, looking at the monitor, figuring out if something is pass or fail. A Boeing 737, for example, if it has a lifespan of let’s say 50,000 hours, we’re looking at over 30,000 mR, Just due to background radiation, plus everything else that it’s going to be exposed to for regular inspections. Right? For extra inspections that are applied to the fuselage and other parts of the airplane, which is regular on a maintenance of this aircraft.

Dr. Bill Cardoso:

So I hope we’re able to give you an overview of how radiation and why radiation can damage electrical components. And how little relative radiation X-ray machines actually apply in radiation components that end up… It’s hard to say that there will be no damage ever. Right? Because, we know enough not to make blank statements like that. But what we want to do is to invite you to a conversation. If you have any concerns, please give us a call and we can work through this problem. Okay? Thanks for your time. I think we have time for a couple of questions, David.

David Kruidhof:

Yeah. Thank you, Bill. That was very helpful. A lot of detail there. Got a couple of questions. Looks like we got two minutes left here. One is asking about the energy to distance ratio. You gave us those four factors causing the damage to component. Is distance a factor there? If it’s an 80kv source run at full power, is that just the number we use?

Dr. Bill Cardoso:

Yeah. That’s a good question. And thanks for bringing it up. Distance is definitely a consideration here because as you know, radiation drops one over R square. So the distance is going to be inside that flux information parameter that we discussed. Right? So the more distance you have the lower the flux, you’re going to have on your part. Especially because we have this cone beam. Right? So the flux you have in your source goes down one over R square relative to the distance, to the source. Very good question.

David Kruidhof:

Another question along the same lines. If I have a populated board and an X-ray inspection system, I’m panning around the board for about five minutes, do I need to calculate that five minutes as the exposure time? Or is that going to be something less than that?

Dr. Bill Cardoso:

So we have a cone beam. Right? Let’s start there. Which means that the radiation is going to reduce exponentially as you move away from the center point on the source. So that’s, data point 1. Data point 2 is, our sources have a specific angle of the target, which means that the cone beam has a very specific shape and that shape is determined by the angle of the target on the source that reflects the electron beam that hits the target. In other words, that angle can be 20 degrees, it can be 40 degrees, it can be 90 degrees for a wide beam source. So based on that angle, you can understand how much of your components on the board have been radiated or exposed to radiation. Right?

Dr. Bill Cardoso:

So for applications that are really concerned with the radiation exposure of the neighboring components on the board, what do we do is we collimate. In other words, we minimize the exposure to neighboring components as we’re inspecting the object under study. Does it make sense? So it’s a way to, basically put a canopy and a shield and protect all the neighbors that we’re not looking at, at a specific time. And we only expose where we’re interested in at specific time, thus minimizing radiation to the neighbors.

David Kruidhof:

Thank you, Bill. Really appreciate answering those questions for us. That’s all the time we have for today. If you have any more questions, give us a call, email us. Or if you’re watching this on YouTube later, go ahead and comment below. And we’re looking forward to having just a Q&A session in July sometime, where we’ll get to some of these questions that we weren’t able to get to in our previous chat, so. Thank you all for joining us. Really appreciate it. And next week, we’re looking at another good chat titled 10 Ways to Find Counterfeit Electronic Components Using X-rays. So be sure to join us again next week. Thank you.

Dr. Bill Cardoso:

Thank you.