Category Archives: Laying It Out

Off-grid thoughts from a burned-out designer turned editor.

‘We are Stronger by What Unites Us’: An Open Letter from PCEA and SMTA

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My name is Stephen V. Chavez CID+ and I serve as the President of the newly formed Printed Circuit Engineering Association (PCEA). PCEA is a trade association for professionals in the electronics industry. There are several other trade associations, some large or small, some old or new that currently exist. We seek to affiliate in a cooperative manner with each one. I have observed that we all attempt to serve the greater good in the electronics industry. Each group has evolved, grown and hopefully we all seek to coexist.

I know at the PCEA many individuals are involved and have historically been involved with IPC, SMT, IEEE, and many other associations. We have served and continue to serve in each other’s ranks. In particular I have the distinguished privilege to serve as an IPC-CID+ Master Instructor. I also serve as a volunteer on some of the IPC standard committees. I am honored for the privilege to serve in their ranks.

A recent column [Ed. note: Because the column was not in PCD&F/CIRCUITS ASSEMBLY, we are not linking to it here.] I read takes issue with the efforts of IPC in our industry, and while well-intended, I do not recognize the picture it paints. Among other things, the author suggests a lack of contact between IPC and the American educational system. In fact, IPC has a robust college outreach program across the US, and dedicated staff to support it. Keep in mind, the effects of the COVID-19 pandemic has slowed many good efforts to engage with engineers and future engineers worldwide, and this is no exception.

Moreover, in my opinion the best path to take is to volunteer our time – as we in the PCEA are doing – to educate our colleagues, the newer members of our industry, and the future
ones. Note the emphasis on the word “our.” IPC is a reflection of ourselves. Its staff, like
that of PCEA’s and many other associations and professional societies, comes from industry. We are all evolving and attempting to serve the industry at large in so many ways. It is a tribute to IPC that it has successfully navigated the changing industry so well over 60 years, and we all owe them a debt of gratitude and allegiance for so many of their great achievements. I once communicated a perspective about the IPC that bears repeating, “IPC is not a Them, rather, it is an Us!”

SMTA – Tanya Martin, Global Executive Director
SMTA has been fortunate to be serving the global electronics manufacturing and design
industry since 1984. We support professionals by facilitating access to national and international communities of experts, as well as accumulated research and training materials from those dedicated to advancing the industry. Some of our most important work is done within our local chapters (national and international) in connecting professionals for education, training, and fellowship. We have invested great resources into the college and university programs and support many SMTA student chapters around the US to be a bridge between industry and academia.

SMTA and PCEA both agree that IPC along with other trade organizations such as SMTA, IEEE, EIPC, others including the newly formed PCEA can coexist and collectively make this industry better. Each of us has the potential to serve the participants. Many of those participants are involved with several trade associations. We have seen IPC successfully reach into the community, academia, professional development, government advocacy, standards development, engineering, manufacturing, OEM business, contract manufacturing and the list can go on… The same thing can be said about the other trade associations. We believe we are all better served by our common welfare and the things that unite us are bigger than the things that divide us. We at the newly formed PCEA are ardent supporters of the IPC and their mission within the industry. We seek to affiliate and be proponents of their mission to serve the electronics industry. We encourage everyone to respect them not for their perfection but for the general overall benefit that our industry receives on so many fronts.

If faced with the question of whether to be givers or takers to the industry, we choose “givers.” Like all the trade associations, IPC is organic and adaptable, addressing the needs of those they serve the best they can. We are grateful and support their mission!

Stephen V. Chavez CID+
Chairman, PCEA
Collaborate, Inspire and Educate
Cell (602)369?3349
[email protected]
www.pce?a.org

The Nature of Disruption

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Just finished recording an hour-long (!) podcast with Judy Warner for Altium’s On-Track sessions. And while I don’t want to spoil any surprises, I will briefly touch on one of the topics we covered.

We got on the topic of disruptions. (I know, I know, it’s every keynote speaker’s favorite word. Sorry.)

In my view, ECAD software has to continue to get more intuitive and easier to use, especially for engineers who may only spend 10 or 20% of their time doing layout. If most of your time is spent using other tools, you won’t necessarily develop the hard-coded means to work the layout software. And no one wants to have to relearn the software each time they use it. So the tools must be more intuitive. And along the same lines, they need to be able to perform integrated functions with other platforms in their native environments. Users are most comfortable when operating in the environment they are familiar with.

To that end, I still think the company that breaks the ECAD industry will most likely come from outside the ECAD industry, if for the stunningly simplistic reason that engineers and their marketing colleagues in one industry are always looking for ways to expand into others.

Which is how it came to be that a maker of PCs (Apple) broke the recorded music industry and then broke phones. And a maker of batteries (Tesla) broke the automotive industry.

Going back aways, a software developer (Microsoft) broke computing, which was all mainframes and dummy terminals back in the day. (Now with app-based tablets and Chromebooks tethered to the cloud, we’ve come close to full circle.) And that same software developer broke video gaming, doing $5 billion in revenue from Xbox related sales last quarter alone and helping to spawn and massive market for online gaming.

My advice to Judy and her colleagues at Altium is to keep improving the design to manufacturing handoff — where so many manufacturability and quality defects take form — and to be wary of any company that comes up with a simpler and cheaper way to go from schematic to actual circuits, because while I don’t know who, how or when, I do know it’s inevitable.

Back in Person

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The Covid-19 vaccine rollout has begun and we can’t wait to get back to seeing old and new friends in person.

To that end, I want to call your attention to the return of PCB East to the Boston area in June.

We will head to Marlboro, MA, for some 55 hours of training across three days (June 15-17) of printed circuit board engineering training. There, SI expert Lee Ritchey will have a couple of tutorials: Printed Circuit Board Stackup Design for High Performance Products, and also Power Delivery System Design.

We also will offer two full days of Rick Hartley, including a brand new talk titled, “PC Board Design for Optimum Fabrication and Assembly.” As Rick notes, Happy Holden has presented at PCB West a few times where he’s explained how fabricators determine pricing for bare boards and how EMS suppliers determine pricing for PCB assemblies. Happy shares what he calls a “Fab and Assembly Report Card,” which is how manufacturers assess and weight the variables that drive cost.

So, for instance, as most readers know, board size is a major cost driver. But, as Rick explains, what most designers don’t know is that aspect ratio of length to width also has a major impact. Two boards with the same number of layers and same number of sq. inches but with a difference in their respective aspect ratios – say one is much longer than wide – will push up the bare board cost. Same with assembly, which has even more cost drivers than does fab. Rick is going to do is discuss these major cost drivers.

Rick also told me that at PCB West he had discussions during the chat sessions with some of the bare board fabricators in attendance. One of them said (I’m paraphrasing here), “At any point in time as many as 90% of our jobs are on-hold, waiting for correction or clarity from the customer, so we can proceed.” In Rick’s opinion, designers are flying blind when it comes to many the cost drivers and what suppliers need at both the bare board and assembly level, hence the reason for so many delayed PCBs. These delays also add cost.

What Rick wants to do is to highlight and talk about the factors that Really drive up cost, like board size and aspect ratio, layer count, Z-axis uniformity, copper balance, etc.

And Susy Webb will have brand new, two-day tutorial for design engineers, “A Comprehensive Guide to PCB Design Necessities.” Her class will feature an overview of the entire process of board design, from start to finish, addressing the EE designing their own boards or the new designer who needs to thoroughly understand all the steps and processes. She’ll cover everything from the electronics and physics involved, how the rise time and controlling the energy fields impact the signals on the board, choosing parts types, schematics and signal and constraint issues, mechanical issues, and so on. Susy is also doing an all-day webinar.

We are looking forward to these any other presentations, and also to the exhibits on Jun. 16. Registration is now open, so visit pcbeast.com for details.

And Then There Were 2

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Isola and Rogers.

That’s what’s left of the US-owned laminate companies today after Taiwan’s Elite Material Co. announced plans to acquire Arlon EMD.

Yes, consolidation has been in the making for years. And with Isola owned by private equity group (Cerberus Capital Management), it’s anyone’s guess as to how stable that number is.

In reality, it was only a matter of time. The US share of global PCB revenues fell from north of 40% in 1984, to about 30% in 1998, to less than 8% in the recession of 2008. It now stands at roughly 4%. Naturally, the supply base is going to migrate to where the revenue is.

Time was, the US was home to several leading names in laminates: Polyclad (now owned by Isola), Westinghouse (acquired by Allied-Signal in 1992), GE (licensed to Cookson, now sold by Isola), Norplex Oak (sold by Allied Signal to Isola parent Ruetgers in 1999, then everntually shuttered), Taconic (bought by AGC), Nelco (ditto), among others. For its part, Arlon was acquired by Rogers in 2014, which then sold part of it to a private equity group the next year. That unit became Arlon EMD, which Elite is buying.

This is not to say there aren’t domestic sources of materials, of course. There are plenty: Ventec and Shengyi are among those that have expanded in the US in the past few years. A startup called Thintronics, with experienced laminate folks like Tarun Amla at the helm, has potential, but is likely years away from impact. There remain domestic flex circuit suppliers too, including DuPont and Sheldahl.

But the vast majority of multilayer and high-performance specialty material suppliers are held by offshore companies. As the US seeks to build back its manufacturing base, it needs to remember how critical the supplier infrastructure is to a successful industry.

What is Slowing Down Your PCB Prototyping Production?

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When it comes to releasing new technology, time is of the essence. New technology needs PCBs, and slowdowns will delay its release. In business, time is money, so delivering PCBs on time is vitally important.

Stated by a PCB manufacturer, if your PCB prototyping production time isn’t meeting the deadlines, then it’s time to look at what might be slowing you down. PCB production does not have to take long, as turnkey production has shown. A traditional PCB manufacturer might not be able to deliver at that speed, but there are steps you can take to improve efficiency.

Too Many Parties Involved

Prototyping is one of the lengthiest steps in assembly. Consider how long it can take to design, produce, and ship prototypes, especially when dealing with facilities all over the world. You can speed up your production by doing all your prototyping within your facility.

If your prototype does not work, then the process often has to be repeated. Each little fix requires the prototype sent to the designers, then to the production house, and then to the testing facility. Instead, these steps can be completed in one place.

Delays in Supply Shipping

Another common reason why prototyping is slow is that you don’t have the necessary supplies on hand. When you have to order supplies for each project, shipping issues will slow you down, especially if your supplies are sourced overseas. You did not only slow your production, but you also add tariffs into the mix.

Since you cannot control shipping, tariffs, or other supply-chain issues, you can avoid prototyping slowdowns by taking control of the accessories and supplies you have on hand. By sourcing supplies yourself and doing it ahead of time, you should be able to get better prices, especially if you do not need to pay for expedited shipping costs.

Outdated Technology

Some PCB manufacturers have outdated machinery. When your machinery is slow, prototyping slows down too. Some manufacturers are turning to CNC milling to speed their prototyping. With the correct programming, a CNC mill can make a prototype in a few hours, and larger models might take a little longer. Granted, it will not be as precise as the finished product. But, isn’t that what a prototype is?

Along with machinery, take a good look at your technology. If you haven’t upgraded your computers or software in several years, you may not be compatible with newer tech or with your clients. The age of your tech should seriously slow you down.

Incomplete Documentation Files

Some manufacturers have issues with prototypes because the collection of files is incomplete. Each PCB requires a package of documents with drill files, lists of materials, CAD files, Gerber files, and instructions and drawings. Without the complete list, the prototype will have missing pieces.

When manufacturers have to fill in the missing pieces, prototype production slows. Therefore, it is important that each project is highly organized, and the files needed for the project need to be accessible for everyone who works on it. This could be an issue with organization, communication, or delivery, and could be fixed by developing an organizational file structure that is stored in the cloud.

Contributed by Chris Dickey, vice president of sales and marketing at SVTronics

“Bogatin’s Practical Guide to Transmission Line Design and Characterization for Signal Integrity Applications” – A Review

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Everything you ever wanted to know about PCB transmission lines – and more – in a digestible format with just the right amount of math to back up the illuminating practical illustrations.

Ed.: Martyn Gaudion is managing director of Polar Instruments Ltd. He began his career at Tektronix in test engineering on high-bandwidth portable oscilloscopes. He joined Polar in 1990, where he was responsible for the design and development of the Toneohm 950, Polar’s multilayer PCB short circuit locator. He became CEO in 2010. He also develops tailored content for the Polar YouTube channel. He reviewed this book for PCD&F.

Hot off the virtual press – a copy of Dr. Eric Bogatin’s new guide to transmission line design appeared in my Artech eBook account.

Do we really need another transmission line book? That’s what Dr. Bogatin asks right at the outset. After reading this new tome from virtual cover to cover, yes we do. This is a thoroughly practical book an peppered with links to Bogatins’s brief informative video explanations which expand and add dynamic content in a way that printed matter alone cannot.

Whether you are a recent graduate who wants a more practical insight to the behavior of transmission lines after doing all the hard work of the pure math side of study, or an experienced electrical engineer moving into the high speed arena – or even a PCB technologist or fabricator wanting an insight into all the mysterious terminology that surrounds the subject – this is a resource book for you. It is equally valuable whether you are dipping into chapters of specific interest, or taking a deep breath and reading from (virtual) cover to cover.

In my day job I spend most of my time helping customers who are new to transmission lines ensure that they document and design them correctly for fabrication, and I confess over the years much is taken as given. By reading Bogatin’s new book I have gained insight into transmission line behavior that is very familiar but I didn’t know the why – and the why makes everything make more sense. 

It is staggering that the electrical behavior of a simple pair of copper traces with a sandwich of dielectric material can generate a book running to 600 pages without loss of interest, but this is exactly what Bogatin does with the subject. Along the way you will find out why you should always think of signal and return paths and not in terms of signal and ground. You will find that while the RF and digital design spaces may run at similar frequencies, the design considerations for both are poles apart. (No pun intended.) You will also discover that simulators and field solvers don’t design circuits – you do – and you best have an idea of what you intend to happen and the expected outcome before reaching for the simulator. Words are important, and Bogatin stresses that though digital and RF and EMC specialists all deal with high-speed signals – and a lot of the jargon is similar – there are often situations where technical terms overlap while their meanings don’t. Bogatin takes an important stance in defining and understanding the terminology to ensure you are understood when working across disciplines.

On measurement – there are many precision tools for measuring high speed signals and time and frequency domain information, all with accuracy beyond your dreams – but as with simulation – Bogatin cautions that unless you understand what you are measuring and how to design your test vehicle, any or all of that expensive equipment can lead you to the wrong answer. Time spent in the measurement section of the book is well invested and will enable you to extract the best possible measurements from whatever TDR/sampling oscilloscope/vector network analyzer you have to hand.

I personally like the examples where Bogatin mixes electronic timescales in nanoseconds with human relatable timescales (days) to bring tangible meaning to his explanations. I also like his informative section on why intuition in the frequency domain does not translate easily (at all?) to the time domain, and that while both are valid and useful you need to work with a degree of selective schizophrenia while working in these domains.

Last but not least, alongside the video links and examples are links to both evaluation versions of commercial tools and useful no cost utilities so you can run the simulations and experiment for yourself.

Martyn Gaudion, June 2020

Bogatin’s Practical Guide to Transmission Line Design and Characterization for Signal Integrity Applications

by Dr. Eric Bogatin

Available from Artech House

Post-Covid, Will Connections Be Scarcer?

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A friend writes to say he’s been about the effects of “social distancing” policies. Will they have a permanent effect on our lives, he wondered. And will they impact events such as trade shows?

It wasn’t the first time I have been asked that of late. The subject also came up on a couple of podcasts I’ve had the good fortune to do, one with Judy Warner of Altium and the other with Mike Konrad of Aqueous Technologies.

My short answer is, I think there will be an impact, but it will swing toward more contact, not less. Indeed, after being cooped up for so long, I think people will crave human connections. Moreover, I don’t think it will have an effect on trade shows. In fact, I think this will reveal lots of holes/flaws in inter-/intra-company digital communications, which gives us all something to work on for the next quarantine (heaven forbid). 

We aren’t the only ones contemplating what happens next. The Boston Globe this week published a piece in which several self-styled business futurists and science-fiction writers expect the world will look like next fall/winter.

I can’t say I’m impressed with most of their responses, which if anything feel exaggerated for effect. But see for yourself.

Ralph Morrison, RIP

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I don’t have all the details, but the industry icon Ralph Morrison passed away Aug. 2.

Ralph spent more than 50 years in the electronics industry. He was responsible for teaching thousands of engineers all about the fundamentals of how voltage and currents work. Up until about eight years ago, he was a constant presence at the PCB West design conferences.

He wrote several books, including Solving Interference Problems in Electronics, Grounding and Shielding Techniques in Instrumentation, and The Fields of Electronics: Understanding Electronics Using Basic Physics.

I didn’t know Ralph in his prime, but we developed an amiable relationship over the past 18 months as he did some writing for us. I truly enjoyed him — he had an economy with words that I will always strain to achieve.

Last year, he put together a series of articles for PCD&F: Voltage in the GHz World, Limiting Radiation from Logic Circuit Boards, Maxwell and Transmission Lines, and The Layout of Fast Logic on Printed Circuit Boards.

According to longtime friend Dan Beeker, a memorial service will take place in October. I will miss his emails and occasional phone calls, and most of all, his kind words about the role we editors play in helping designers and engineers better understand their craft.

What is a Centroid File?

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Call it what you may, but surface mount assembly robots need a magic file to determine where to place your components and how to orient them. We call it a centroid. What is a centroid file and why is it important to your PCB assembler?

Many assemblers use automated equipment to place surface mount components on PCBs. One of the tools we use to rapidly program these machines is the centroid file (aka insertion, pick-and-place or XY file).

Some CAD packages automatically generate this file, some will not. Sometimes you may simply need to modify the file, and some assemblers can make minor changes to the file or create it for you for a small fee.

Ultimately, the centroid file describes the position and orientation of all surface mount components on the PCB. A centroid file includes: the reference designator, X and Y position, rotation and the side of board (top or bottom). Only SMT parts should be listed in the centroid file the basic format for the centroid file is a comma delimited (.csv) file with data in the following order: RefDes, Layer, LocationX, LocationY, Rotation.

Here’s a breakdown of the data:

RefDes
The reference designator that matches your BOM and PCB markation.

Layer
Either the word “top” or “bottom.” This is not necessarily the CAD layer designator. Just “top” for a part located on the top of the board and “bottom” for parts on the bottom side of the board. Top is often referred to as the component side and bottom the solder side by assemblers and fabricators.

Location
The “LocationX” and “LocationY” values describe the part’s offset from the board origin. The location values require that the part origin be centered in the part. The board XY origin of 0,0 is in the lower left corner of the board. The 0,0 origin for the bottom of the board is in the lower left corner, looking at the top of the board, though the board. Preferred units are in inches (0.0000″).

Rotation
Rotation goes counterclockwise for all parts on top and clockwise for parts on the bottom. In both cases, this is from the perspective of looking at the top of the board. For bottom side parts, it is looking through the board, still from the perspective of looking at the top of the board.

LED & Diode Markation Guidelines for PCBs

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Have you ever had an LED or other diode placed backwards? PCB assemblers work hard to place every component from the largest, highest pin-count logic chip down to the smallest passive components and micro wafer-scale BGAs correctly every single time. A key element of that accuracy is our understanding of your board and the component markings.

If you use surface mount diodes or LEDs, you probably understand the challenges involved in correctly and consistently indicating diode polarity. LEDs are usually cathode negative, while zeners and uni-directional TVS diodes can be cathode positive. Barrier diodes can be either orientation. It all depends on whether the diode is a rectifier, an LED, a uni-directional TVS, part of a daisy-chain and a host of other considerations.

When you start looking at the CAD libraries, you not only have all the differences from that manufacturer, you may also have different markation schemes from each CAD package developer and from each library builder.

Guidelines for diode polarity mark silk-screening — the diode symbol, “K” for cathode or “A” for anode. To ensure the best accuracy, we recommend extra care in marking diodes to remove any ambiguity.

The preferred method is to place the diode schematic symbol in the silkscreen. You may also place a “K” for cathode adjacent to the cathode. “K” is used because “C” could imply that the spot wants a capacitor. An “A” adjacent to the anode on the board works too, though it’s less common. If you are producing a board without silkscreen, put the mark in the copper layer or submit a clear assembly drawing with the other board files.

Relying on +, – or _ are not definitive in what they indicate and are not recommended. For example, a “+” or “-“ sign isn’t good enough, because it’s not always true that current flows through a diode from the anode to the cathode. For the common barrier diode or rectifier, it’s a pretty safe bet. However, with a zener diode or TVS, it’s not necessarily true. That is why marking a diode on your PCB with the plus sign (+) is not good practice.