Tim's Takeaways: The Misadventures of High Voltage and Other Related Problems with Power

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If you’ve read my column before, you know how much of a fan I am of aviation, especially when it comes to older airplanes. You can imagine how ecstatic I was when, 11 years ago, my wife gave me the greatest gift of all: a half-hour ride on a fully restored WWII B-17 Flying Fortress. This plane was the real deal, folks. A four-engine heavy bomber stuffed with gun turrets, narrow and cramped crew areas, and the cold hard metal of unforgiving hardware that could give you a serious bruise on the forehead if you weren’t paying attention. From wingtip to wingtip, the “Liberty Belle” was saturated with a rich ambiance of history that emanated from every one of her nearly 400,000 rivets that held this aircraft together. One by one, the four 1,200 horsepower Wright Cyclone engines came to life, and together with the other passengers and crew, we took off on that warm and sunny day from the airport in Hillsboro, Oregon.

Haag_Jan_Fig2_cap.jpgThere were a couple of things that happened during the trip that you might find interesting. For example, I really did poke my head out of the open upper hatch in the radio room. Maybe sticking my head out of an airplane in a 120-mph slipstream wasn’t the brightest thing I’ve ever done (I did take my glasses off first), but I got a great picture out of it. At another point in the trip I was in the nose of the plane peering through the Norden bombsite at the city below me. Even though I knew that the dummy bombs were not real, and they were permanently attached so they couldn’t be dropped, (plus the bomb bay doors were closed, and the bomb release mechanism wasn’t even electrically connected), I still couldn’t make myself flip the bomb salvo switch. I think that it just had gotten a little too real for my imagination at that point, and I didn’t want to take a chance on blowing up the city.

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There were plenty of other interesting things about that trip such as exploring the aircraft, playing with the radio equipment, training the guns around to get my sights on imaginary enemy aircraft, and enjoying the trip as the pilots flew us across the countryside. Oh, and just for excitement, about halfway through the trip, the pilots announced that the plane had suffered a problem in the electrical system. They didn’t give us much in the way of details, but I did hear the phrase “a battery exploded,” which resulted in the electrical system being knocked out on the left side of the plane. Thankfully this didn’t affect how the plane was flying, as an older plane like this didn’t rely as much on electrical systems for flight as a modern plane would. However, there was one big problem that was unavoidable: the pilot was unable to lower the left side main landing gear wheel and the tail wheel from the cockpit. As you can guess, without all of the landing gear down and locked, our landing was undoubtedly going to end up in a crash.

Understanding Higher Voltage
Ever since that flight I’ve often wondered about that electrical problem, and the mental image of a battery exploding somewhere in the internal workings of the B-17 is a very intriguing one to say the least. Did the battery suffer an internal short and failure, or did a mechanical anomaly cause something to get crossed up resulting in a more exciting short with sparks and smoke? Maybe the incident was due to an over-voltage problem somewhere, or just maybe the battery actually did explode? Whatever was the root cause of the problem, it is obvious that our plane experienced a serious electrical power failure that was unplanned and a surprise for everyone on board. With that flight serving as an example of the consequences of an electrical failure, it has motivated me to understand more about the different requirements of power and higher voltages in my own small world of circuit board design.

Most PCB designers are aware of the unique power requirements for the garden-variety digital design. Power supply component placement must be kept tight to keep the trace routing as short as possible for lower inductance and to reduce the potential of generating noise. The connections between these parts should be routed with wide traces on one layer only, avoiding the use of vias, except for the vias that extend into the ground plane to help with thermal dissipation. And it’s also important to keep these power circuits isolated from sensitive digital and analog circuitry for the best signal and power integrity of the design. However, what designers are less familiar with is how to work with high-voltage circuitry, which is increasing in importance as more high-voltage design work is being done.

High-voltage circuitry can be found in everything from computers and consumer products to large industrial equipment, and designers must learn the intricacies required to lay them out. For instance, higher voltages can arc between exposed metal conductors on a circuit board if those leads, pads, traces, or other areas of metal are too close to each other. With the unexpected arcing of high-voltages also comes the breaking down of the different insulating barriers in and on a circuit board. Eventually this continued arcing can create an actual short between the exposed conductors, creating a potentially dangerous situation that can cause a lot of damage.

Clearance and Creepage
To eliminate the potential of arcing in high-voltage circuits on their boards, it is essential for PCB designers to understand both clearance and creepage spacing rules in their design. While clearance is the direct space between two metal conductors from a line-of-sight perspective, creepage is the space between the two conductors that follows the physical contours of the circuit board. These clearances must be adhered to for the board to avoid problems with its high-voltage circuitry. Even placing high-voltage components on opposite sides of the board may cause a problem if the parts end up violating the allowed creepage spacing distance.

There are many other aspects of high-voltage circuits that PCB designers also need to understand in order to successfully lay out these boards. For instance, which board materials are better for applications of high-voltage, what copper weight should be used, and how can that copper be distributed throughout the board to ensure its manufacturability? Fortunately, this edition of Design007 Magazine is focused on high-voltage design, and there are numerous experts weighing in here that can offer some help.

But Did We Crash?
Now, back to my crippled B-17 flight. If you’ve ever watched the movie “Memphis Belle,” you know that B-17s were equipped with manual cranks for lowering the landing gear in case of an emergency. During war time, these Haag_Jan_Fig4_cap.jpgplanes were always getting shot up and losing their electrical or hydraulic systems, and the cranks were used more often than you might expect. The crew on our plane was able to crank down the landing gear manually without too much difficulty, allowing us to land normally. And with the time it took to crank the wheels down, plus the need to burn off some fuel for safety’s sake, our trip extended much longer than the half hour it was originally scheduled for. As you can guess, this didn’t generate any complaints from me. In fact, I tried to get the flight engineer to let me have a go at cranking the gear down myself so I could claim partial credit for “landing” the plane. Sadly, he flatly denied my request, mumbling something about insurance liability or some such nonsense. Pity.

And with that our trip was all but over except for one last detail. You see, without a functional electrical system, the warning bell we were told to listen for didn’t ring as it was supposed to when it was time to strap in for landing. A couple of us were still in the nose of the plane wondering why the airport was getting so big in the window when the crew realized we didn’t know that the Liberty Belle was on its final approach for landing. Once they told us to run back to our seats (which isn’t easy in that plane), we barely had enough time to buckle up before the wheels plopped safely back down onto Hillsboro’s runway. With several fire trucks following us “just in case,” we taxied to our parking spot where the engines were finally shut down and our trip was safely concluded. And although some of my fellow passengers were experiencing different levels of anxiety due to our in-flight emergency, I must confess that I had the time of my life.

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Not every PCB design we lay out will play a role in what could become an in-flight emergency. However, as more and more designs are increasing their voltage requirements, the consequences of circuit board failures due to how their high-voltage circuits are laid out can have a serious impact. We all need to put as much effort into understanding how to design for high-voltage as we do for high-speed, analog, RF, or any other circuitry types. After all, learning new types of PCB technology is what makes our jobs interesting, and the way things are going, our jobs look like they are going to be interesting for a long, long time. Until next time my friends, keep on designing.

This column originally appeared in the January 2022 issue of Design007 Magazine.

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2022

Tim's Takeaways: The Misadventures of High Voltage and Other Related Problems with Power

01-27-2022

If you’ve read my column before you know how much of a fan I am of aviation, especially when it comes to older airplanes. You can imagine how ecstatic I was when 11 years ago my wife gave me the greatest gift of all; a half-hour ride on a fully restored WWII B-17 Flying Fortress. This plane was the real deal folks. A four-engine heavy bomber stuffed with gun turrets, narrow and cramped crew areas, and the cold hard metal of unforgiving hardware that could give you a serious bruise on the forehead if you weren’t paying attention. From wingtip to wingtip, the “Liberty Belle” was saturated with a rich ambiance of history that emanated from every one of her nearly 400,000 rivets that held this aircraft together.

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2021

Tim's Takeaways: Say ‘No’ to File Hoarding: Data Management Tips

11-24-2021

There are a lot of different types of “collections” in life that need managing, and like my proliferating pile of tax paper publications, they all need their own eloquent solutions to keep from getting out of control. Take for instance the amount of data that is generated during the design of electronics. The first thing to consider in our world of PCB design is just how much data there is that needs to be managed. From a casual overview it may not seem that extensive, but let’s break the average design down into its four separate pieces. This gives us the schematic, circuit simulation, PCB layout, and analysis, and that is just a generalization. Designs often have more pieces than that in them, especially when you consider the depth of system level design.

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Tim's Takeaways: The Collaborative PCB Design Process—A Necessity for Efficient Manufacturing

09-24-2021

Circuit board design used to be a more complicated and lengthy process than it is now with the need to build scores of test circuits, develop multiple prototypes, and toiling with manual design operations. The one good thing about all of this time was that it gave ample opportunity for everyone to be involved.

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Tim's Takeaways: Some Timely Advice

07-14-2021

Who inspires you to be a better designer? For Tim Haag, he finds motivation in the story of Bert Christman. Read on for how this daring Navy pilot's life relates to advice in the world of circuit board design.

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Tim's Takeaways: DDR Routing, and Other Big Fish in the Lake of Technology

05-21-2021

Tim's fishing story relates well to designing circuit boards. Intrigued? Read on, he explains how "there's always a bigger fish."

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Tim’s Takeaways: Conquering Layers of Challenges in PCB Stackups

01-25-2021

When he first started laying out printed circuit boards many years ago, Tim was working for a computer systems manufacturer whose PCB designs were all multilayer boards. While there were a great many things that I learned during my time working there, it also fostered one bad habit; He became accustomed to relying on being able to use multiple layers for routing instead of planning a more efficient layout. Here, he breaks it all down.

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2020

Tim’s Takeaways: PCB Vias, ‘You Have a Go’

11-13-2020

Do you remember the old TV show “Stargate SG-1?” With the exhortation of “SG-1, you have a go” from their commanding officer, the stargate would instantaneously transport an intrepid band of heroes to new and exciting locations each week. Tim Haag details his realization that the stargate is nothing more than a giant via in space!

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Tim’s Takeaways: Thermal Management for PCB Designers—Staying Out of the Fire

09-09-2020

If there’s one thing in life that really feels the pressure of being in the hot seat, it’s the PCBs that we design. But PCB designers often feel a lot of pressure while doing their work, which puts them squarely in the hot seat. Tim Haag shares four techniques in thermal management for PCB designers.

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Tim's Takeaways: Navigating Industry Expectations

05-29-2020

While some expectations are normal—and, well, expected—in the workplace, there are also those that do more harm than good. Tim Haag unpacks negative expectations and shares suggestions for improving communication in the workplace, as well as positive expectations that you can set for yourself.

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Tim’s Takeaways: Working From Home—5 Tips for Newbies

03-24-2020

Due to the COVID-19 outbreak, many people who have worked in an office environment for their entire career have suddenly found themselves shifted to working remotely. At first, this may seem like it isn’t that big of a change, but it may be a bigger deal than you realize. Tim Haag, who has worked from home for over 17 years, shares five tips for making the most of this situation and working successfully from home.

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Tim’s Takeaways: Clearing Up the Buzz

02-14-2020

My first “real” job in the world of electronics was working at a Radio Shack store back in the late ‘70s. It was a step up from flipping burgers, but it didn’t last long. However, there was one notable aspect of that job; I was there during the time that Radio Shack introduced its first personal computer—the TRS-80. Although it is practically unimaginable now, in those days, there wasn’t much in the way of personal computing available for the general consumer.

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2019

Tim's Takeaways: Realizing a Higher Standard for PCB Design

10-09-2019

To the untrained eye, one circuit board may look pretty much like any other, but as we know, there are major differences between them. Not only are they different in purpose and design but also in how they are manufactured for specific industries. If you are designing medical equipment, for instance, you will have to meet many different regulatory requirements from organizations, such as the Food and Drug Administration (FDA), World Health Organization (WHO), and International Electrotechnical Commission (IEC), among others.

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Tim's Takeaways: Clear Communication Takes the Cake

07-10-2019

Whether baking a cake or building a circuit board, it’s all about clear communication. If the person writing the recipe had not made the choice to clearly communicate what their intentions were for baking that cake, I would have been lost. A missing ingredient here or an incorrect oven temperature there and my birthday surprise would have ended up in the garbage in the same way a successfully built circuit board starts with clear communication from the designer. Circuit board manufacturers want to create a perfect PCB for you, but they can only do so to the extent of the instructions that you give them.

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Tim's Takeaways: Rules Keep You from Crossing the Line

06-20-2019

Driving rules are designed to keep drivers between the lines of traffic instead of crossing over those lines into dangerous situations. Similarly, design rules are also intended to keep PCB trace routing between the lines instead of crossing over them as well. But you might be surprised how many people refuse to use the full potential of their DRCs to protect themselves, and in some cases, refuse to use them at all.

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Tim's Takeaways: I Think I’ll Go for a Walk

04-08-2019

Many years ago, my boss at a PCB design service bureau had his own unique way of encouraging us to take a break. He would come through the design bay and call out in his deep baritone voice, “DARTS!” and we would all follow him into the break area for a quick game. In addition to the benefits of taking a break, forcing our eyes to focus in and out as we threw a dart was a great way to relieve us all from the eye strain of older CRT monitors.

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Tim's Takeaways: A Job Worth Doing

02-28-2019

I get it. We PCB designers are made of the kind of tough stuff where we will work ourselves to death if given the chance. But in our all of our efforts, are we really doing it right, or could we somehow be doing it better? Let’s take a moment to consider some other ways that we might help ourselves to improve.

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2018

Tim's Takeaways: Contract Positions—Go the Extra Mile

10-10-2018

For newbies just entering the industry or experienced designers who have always worked for a corporation, the transition to contractor can be a real culture shock. The allure of working from home and setting your own hours can quickly be replaced by the realities of chasing jobs and wondering where your next payday will come from. However, there are some wonderful aspects of working as a contractor that can make it very worthwhile.

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Tim's Takeaways: Where Have All the Designers Gone (and Who Will be Taking Their Place)?

08-17-2018

We have a lot to pass on to the new designers. We must stress the importance of understanding of the roots of our industry and why this design knowledge is important. I have worked with many designers who don’t understand anything about the output of their design files. They go through a procedure, hit a series of commands, and presto: The design files are all wrapped up in a neat little zip file ready to go out to the manufacturer. That’s all well and good, until something breaks or a manufacturer has a specific question. It would be a great thing to make sure that the designers of tomorrow understand what a Gerber file and an aperture list really is.

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Tim's Takeaways: Hiring the Right PCB Designer

06-04-2018

Like the rest of you, I’ve had times of unemployment, when your daily job is looking for work. You find yourself writing and then rewriting your resume, searching online forums and job search sites, and applying to every job that you can find. I’ve also hired people, and I know what hiring managers face. But hiring managers may be hurting their companies by drawing up a list of expectations so tight that highly qualified people may be slipping between the cracks.

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Will Cool Technology Attract the Next Generation of PCB Designers?

04-17-2018

If I had the opportunity to design some boards that went into medical detection equipment like my new blood pressure cuff, I would be extremely motivated to do that. Maybe what we should be focusing on is not just playing with the new toys, but showing the younger generation different ways to think about how they can improve upon these new toys.

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Customer Support: What do PCB Designers Really Want?

03-19-2018

First, let’s throw a leash around the elephant in the room. That’s my way of saying, “Here are some things that designers want, but we in the support business just can’t give it to them.” The first one that comes to mind: Customers have asked, manipulated, and even tricked me in their attempts to get free software.

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Tim's Takeaways: Good Support Isn’t Just for Customers

03-06-2018

I have been working in PCB CAD tools customer support for years and years, and it isn’t that often that the tables are turned and I have someone who is supporting me. I’ve got to say, it was a pleasure being the recipient of some quality support.

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2017

True Design Efficiency: Think Before You Click

10-09-2017

At the captive shops that I’ve worked with, where the designers were more involved in the entire design cycle and had better access to the corporate libraries, staff engineers, etc., the story was often the same. Some designers would jump into the deep end of the pool of design without any thought to drowning while others would be so busy lacing up their life preservers of preparation that they would take too long getting out of the shallows and into the depth of their design. So, what’s the best approach here?

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Tim's Takeaways: It Really Wasn’t My Fault

09-07-2017

I once received verbal instructions from an engineer who directed me to make a certain change. I didn’t think anything of it. Many months later, this same engineer told me that there were troubles with the board and all its successive versions because of the change that I had made. He ended up making it right in the end. But in hindsight, what could I have done to save myself a couple of months of suspense and worry?

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Tim's Takeaways: Stepping into the Great Unknown

08-16-2017

Many years ago, I was given the opportunity to switch my career path from senior circuit board designer to CAD systems administrator. I wasn’t certain that I wanted to give up the comfort of being a designer; after all, I had been one for a long time. But I knew that this transition would help my overall knowledge base of everything CAD-related, as well as better position me in my quest for a management position. So, I pulled the trigger and accepted the new job even though the idea of stepping into the great unknown like that was very intimidating.

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Tim's Takeaways: Design Tools of Tomorrow--A Real 'Marvel'

04-05-2017

Imagine if you could interact with your design as a hologram floating in front of you the way Tony Stark did in the movie "Iron Man." Wouldn’t it be amazing if you could pick a section on your holographic design with your hands and expand it to the point where you could peer into it, spin it around, and manipulate it as you desired? Want to push a trace down to a different layer? Just give it a nudge in the right direction and the holographic display changes it to the next layer. Don’t like the way a certain area fill looks? Then just grab it with your fingers and pull it out and throw it into the virtual garbage can.

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Tim's Takeaways: 'Sparks' to the Rescue in RF Design

01-03-2017

Just like the early days of radio where Sparks the radio specialist was in demand to get the job done, we now need RF specialists to work together with electrical engineers to create the intricate designs required for RF circuits. You are now Sparks, the go-to specialist who will take care of RF design business.

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2016

The Basics of Hybrid Design, Part 3

06-16-2016

The world of hybrid design is growing, and we have lots of hybrid-specific functionality built into our software that helps designers meet and conquer the unique hybrid design requirements that they are faced with. And yet many designers out there (and I used to be one of them) have no idea what is meant when people start talking about hybrid design.

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The Basics of Hybrid Design, Part 2

05-16-2016

In the first part of this series, we discussed the basics of hybrid design from the PCB designer’s perspective, and here we will continue that discussion.

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The Principles of Hybrid Design, Part 1

04-25-2016

What exactly is a hybrid design? We are seeing more and more of our customers exploring the world of hybrid design, and we are getting new customers for whom hybrid design is their sole focus. The world of hybrid design is growing and we have lots of hybrid-specific functionality built into our software that helps designers conquer the unique hybrid design requirements.

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2015

Tim's Takeaways: The Utility Belt

05-12-2015

The utility belt is a great thing to have. Batman would be long dead without his, and Tim “The Tool Man” Taylor would be useless without his. But for a circuit board designer, a utility belt is equally important. All of us at one time or another will have questions about the CAD system we use, and one essential tool to have in your utility belt is a list of people you can go to for help. At the top of this list should be your CAD system’s friendly customer support staff (like me).

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DFM: The PCB Designer as Arbitrator

04-08-2015

Design engineering is usually a combination of electrical and mechanical engineers. Although these two groups can have their own dramatic conflicts between each other, they will usually end up working together because they ultimately serve each other’s needs. But the manufacturing engineering requirements usually come from a completely different department or from an outside manufacturing vendor.

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2014

Like it or Not, You're a Role Model

12-24-2014

"During the years that I built my skills as a circuit board designer, many people helped shape my character. Some were impulsively brilliant at laying out a board, while others were steady and consistent in their approach to work, dotting every 'i' and crossing every 't.' But they were all patient with me, answering my questions, showing me the ropes, and setting good examples for me to follow," says Columnist Tim Haag.

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Blink and You Will Miss It

11-05-2014

Tim Haag writes, "Friedrich Nietzsche said, 'That which does not kill us makes us stronger.' Well, that adage certainly proved to be true in my situation. If I hadn't been ripped from my secure position and forced to contract for a short season, who knows how my future would have eventually unfolded. And if it hadn't been for that brief season of hardship, would I have had the strength and flexibility to succeed later on?"

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Tim's Takeaways: Blink and You Will Miss It

11-05-2014

Tim Haag writes, "Friedrich Nietzsche said, 'That which does not kill us makes us stronger.' Well, that adage certainly proved to be true in my situation. If I hadn't been ripped from my secure position and forced to contract for a short season, who knows how my future would have eventually unfolded. And if it hadn't been for that brief season of hardship, would I have had the strength and flexibility to succeed later on?"

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There Are No Stupid Questions

09-10-2014

Many of us who have been designing boards for years have had to deal with annoying questions from "the kids." You know who I mean: The rookies, newbies, greenhorns, or puppies just starting out in their design careers. We've all had to answer questions like, "Why is library development so important?" or "Why is solder mask green?"

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Tim's Takeaways: There Are No Stupid Questions

09-10-2014

Many of us who have been designing boards for years have had to deal with annoying questions from "the kids." You know who I mean: The rookies, newbies, greenhorns, or puppies just starting out in their design careers. We've all had to answer questions like, "Why is library development so important?" or "Why is solder mask green?"

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Design Rule Checks - For Your Protection

07-09-2014

Columnist Tim Haag writes, "I have designed multitudes of PCBs over the years, but I have a confession to make: It can be hard for me to run that final design rule check. I know that it is important, but at the end of a long design cycle, I just want to be done. I don't want to redo anything, and I sure don't want to look at my own errors. Do any of you feel that way?"

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Tim's Takeaways: Design Rule Checks - For Your Protection

07-09-2014

Columnist Tim Haag writes, "I have designed multitudes of PCBs over the years, but I have a confession to make: It can be hard for me to run that final design rule check. I know that it is important, but at the end of a long design cycle, I just want to be done. I don't want to redo anything, and I sure don't want to look at my own errors. Do any of you feel that way?"

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Customer Support: Not Just for Customers Anymore

06-04-2014

Columnist Tim Haag writes, "In my role as the customer support manager, I have seen plenty of examples of customer support. But my point here is not to focus on customer support as a function of a support technician. Instead, I want to explore the concept of how we should all strive to provide the best level of customer support in our jobs, no matter what we do."

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