What Do You Do If You Can’t Have Reference Designators?

The first answer to that question is probably going to be along the lines of, “Put them on the board.”

But, sometimes you can’t have reference designators on your board. Maybe it’s too densely populated and there isn’t room. Maybe, for aesthetic reasons, you’ve chosen to leave them off. With some products, like development boards, it’s sometimes necessary to use the space for instruction or functional identification and reference designators would confuse your customers. Figure 1

It’s always best to put reference designators as close to the part as possible, and on the same side as the part, but if that’s not possible, you can still create an assembly drawing. When laying out the board, put the reference designators in a different layer than the text you want in silk screen. Then, create a PDF that has all the component outlines in their place, with reference designators. Make one for the top and one for the bottom. Call this document “assembly drawing” and include it in the files sent in to be manufactured.

Figure 1 shows a good assembly drawing format. It has reference designators and polarity marks.

You might ask why reference designators are needed when all the surface-mount parts are machine-assembled. First, any through-hole parts are hand-assembled. Their locations and board side needs to be clear for the people stuffing them.

Second, CAD systems don’t always have 100% accurate information. If the center point of the footprint is off, surface mount machines (ours and anyone else’s) will center the part where file says to put it, which, in the case, would be the wrong spot.

The reference designators are also part of quality control. It’s another opportunity to remove ambiguity. Ambiguity bad. Certainty good.

Duane Benson
Car 54, where are you?


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Smartwatches Will Never Be A Dominant Technology


We saw a while ago that the decline in sales of PCs, tablets, and smartphones is easy to understand.  There are two main drivers of this trend:

  1. The market is saturated. In other words, almost everyone that wants one has a device.
  2. These devices have such high capability that upgrading is more often done due to worn out units. It is not driven by the need for the new, but only to incrementally improve existing devices.

It is interesting to consider how much effort has been spent on the reliability of electronic solder joints when the anecdotal experience of most people is that, if a unit fails, it is more often due to some mechanical problem like a worn out keyboard or an audio plug that no longer works.  We are replacing old units, not for electrical fails, but for mechanical wear issues.  It will be interesting if someone starts addressing this need more vigorously.

Even with the market for PCs, tablets, and smartphones stabilizing, the numbers of units sold per year is still large. PCs sell at a rate of about 250 million per year, and tablets at 150 million per year, as discussed in the post mentioned above. Smartphones are truly a phenomenon however, with units per year in the 1.5 billion range. Time will tell, but I wouldn’t be surprised if smartphones will eventually be considered more transformational than PCs.

While such devices are sold in hundreds of millions to billions annually, smartwatch yearly volumes are only in the 10s of millions.  I don’t see this figure moving upward much ever.  Let me explain.

Having used an Apple Watch for over a year now, I think I am qualified to discuss the usefulness of this and similar devices.  First of all, let me state that I like my Apple Watch and use it quite a bit. I like the feature that I can see the outdoor temperature with a flick of my wrist, and I use the fitness tracking app constantly. I used to miss an occasional phone call when my mobile phone was on vibrate. However, with my Apple Watch also vibrating on my wrist, such misses are a thing of the past. In addition, I can pull a Dick Tracy and speak into my watch’s telephone feature if I want.

But these features are not enough.  First of all, I must have an iPhone for the Apple Watch to work, but, more importantly, the small size of the watch’s face makes it difficult to use by tapping. Remember calculator watches? It is simply easier to just get out my iPhone 6S to perform various tasks. This is an important aspect of the interaction of humans and electronics; human size factors dictate that a certain minimum size exists for a device to be useful. For most folks, this size is that of an iPhone 6S,® or others might need an iPhone6S Plus, or the largest Samsung Galaxy or equivalent smartphone from other manufacturers.

Considering its diminutive size, I don’t see the smart watch being a dominant technology unless someone invents a projection screen device as envisioned in the Cicret.  And please remember the Cicret is only a concept, not a working device.


Dr. Ron

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Bank Shots

My latest editorial looks at how buyers in the electronics supply chain are using their suppliers as an extension of their bank.


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Mycronic-Axxon Deal a Symbolic Milestone

Mycronic’s purchase of electronics dispensing OEM Shenzhen Axxon Automation Co. today signals a novel, if inevitable, milestone in the SMT processing equipment history: Chinese process equipment OEMs have reached the point where they are sufficiently viable and significant for Western companies to invest in.

Certainly there are no shortage of domestic Chinese OEMs. But relatively few have reached the technology or market share level needed to draw the interest of Western buyers.

No more.

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The Last VCR

The news that the supposed last maker of VCRs, Funai Electric, will cease production on the video medium at the end of this month took me back to this blog item I wrote in 2009.

That’s when I retired my previous VCR, a Hitachi VT 2000A workshorse that served me well for 21 (!) years.

They say otherwise, but I’m still convinced that my first college roommates invited me to live with them because I was the only one they knew who had one. Happily, the friendship has outlasted the machines.

So sayonara to one of my favorite technologies!

P.S. I still have a few blank cassettes, if you know anyone who is looking.

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‘Mike Buetow Humor’

When the reader titles their email “Subject: Mike Buetow humor,” you know I’m opening that one first.

Reader TE writes:

Just going through the July 2016 issue when I came across two (well, three really) very interesting announcements.

On page 14 is a small blurb in the first column: “Canadian mining firm First Majestic Silver says a surge in smartphones and tablets is creating a silver shortage that could send prices up 775%.” Now go over to page 15, first column and you will see not one, but two different articles, one on smartphone sales slowing by 2.6% and the second that tablet shipments will decline by 9.6 % this year.

These opposing announcements seem to be right up your alley regarding the irony of our industry, and even perhaps our times. Both can’t be true, so now I am wondering if either is. It’s a big lol from my corner.

Well played, TE: I loved the note, and your observation absolutely appeals to my sense of irony!

I can possibly account for why both could be true. The silver market, like any commodity or precious metal index, changes daily and can be highly speculative. If you look at the Metals Index chart on pg. 15, the Handy and Harman Silver index jumped 15% between Apr. 4 and May 9 this year, then fell 6% by the end of May.

Second, smartphone growth appears to be declining in terms of its rate, but still rising overall. So growth this year will be 3% instead of 11%. I wouldn’t call that a “surge,” but who knows what goes through the minds of those good persons at First Majestic Silver. Also, overall handheld phones shipments are actually growing — probably in the high single digits this year. And it’s also possible that silver speculators are guessing there will be a spike in the second half because of new models that will overcome the lackluster first half sales.

As for the tablets, well, I don’t have a good rationale for that one. We have two in my house and both are used as expensive coasters.

All that said, I highly doubt the silver price will “surge” (or even grow) 775%. At least not because of electronics demand, anyway. After all, election years do play funny tricks on things.

But that’s a column for another day.

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What Route Do You Take?

There are a lot of polar opposites in the “what is my philosophy” world: Mac vs. PC, on shore vs. off shore manufacturing, Ford vs. Chevy, Atmel vs. Microchip (well, maybe not that one so much any more), auto router vs. hand route…. Yes, I’m specifically avoiding political opposites.

DB 1Routing is what I’m really interested in today. The conventional debate is hand vs. auto route. CAD companies spend a lot of time and money on autorouters, but there’s definitely a line of thought that says it’s not ready for prime time yet. This shirt designed by Chris Gammel, on Teespring pretty much says it all.

But, it’s more complex than that. Most auto-routes end up requiring some hand work, either to finish routes that can’t be found automatically, or to clean up a few less than efficient choices. There are differing techniques for complete hand-routing as well.

I often find myself looking at a layout project a bit like a chess game. I don’t just start at one end of the board and work my way to the other side. I tend to focus on specific parts or critical requirements first, like signal paths that need to be short, or sections with more critical grounding requirements. (The image above isn’t mine. It’s from the Beagleboard.)

When it gets to the mass, I tend to try and think ahead, projecting moves out, as though it were a chess game. When I’m looking for the best route for signal path A, I try and think ahead to how it will impact B, D, D… as far ahead as I can go.

I’m not sure if doing it this way is easier, of if it would be better to just start routing and then re-route as I run into roadblacks. What about you? How do you approach a complex layout?

Duane Benson
Holy cow. I Googled “Trust no one” to get some ideas for my signature
Never do that. It’s going to take a week to shake off all the negativity


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Eagle’s New Nest

It’s been almost a month since Autodesk acquired Cadsoft, and more importantly, its Eagle line of CAD tools, from distributor Premier Farnell. Yet there’s been nary a peep from Autodesk on how it plans to adopt or implement its new toys.

Autodesk, of course, is a developer of 3D design software for a variety of uses, including engineering. The companies had an existing relationship leading up to the sale. Newark element14, a Premier Farnell subsidiary, has been distributing Autodesk’s MCAD tools since last year.

I understand why CAD tools appeal to distys: they represent an opportunity to lock in customers by leveraging the designer’s favorite tool to act as a conduit to ordering parts. And Premier Farnell wasn’t alone in this regard. Mentor and Digi-Key teamed up in late 2014 to offer a simplified flow of schematic and layout tools. (While that arrangement still exists, there’s been precious little news about it since its launch.)

But distribution and software development are too very different animals. Neither one is easy, and they require different skill sets and strategies. I’m not surprised, then, that Premier Farnell decided to cut bait.

The deal from Autodesk’s perspective is infinitely more intriguing. It’s a $2.5 billion software company that has built its name on easy-to-use 3D modeling tools. It says its goal is to “provide the world’s most innovative, and engaging design software and services … to digitally visualize, simulate, and analyze projects.”

Will Eagle go the way of Ohio Design Automation, which was purchased by PTC in 2004, and whose flagship electronic design verification product InterComm is now rolled up into PTC’s Creo flow?

I don’t think so. As the MCAD/ECAD link grows tighter, Autodesk almost assuredly will be looking to leverage Eagle with its extensive customer base. Eagle’s cost structure may change: Premier Farnell knocked the higher-end commercial version prices down quite a bit. But when Autodesk breaks its silence on Eagle, I think it will be in a big way.

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Building Boards for the Intel Edison

I’ve recently spent some time getting familiar with the Intel Edison. The Edison has a dual-core 500MHZ Intel Atom processor, with built-in Wi-Fi and Bluetooth. It comes with 1GB of RAM, 4GB of eMMC internal storage, and a USB 2.0 OTG controller. It doesn’t bring any of the connectors (power or signal) out in a usable form. Rather, it’s designed to be plugged onto another board through a 70-pin high density connector from Hirose.

I designed a small board with I2C (both 5V and 3V connectors) and a micro-SD card slot. My board still doesn’t have the power or console connectors. For that, I’m using a base board from Sparkfun.

Figure 1

Figure 1

Step one of the assembly process, is, of course, to design and layout the board. Using the Sparkfun open source designs as a jumping off point, I ended up with the nice, compact layout (1.2″ x 1.75″) shown below in Figure 2.

Figure 2

Figure 2

After getting the files ready and placing a turnkey order on our website, I followed the board through with my camera. Here it is after offline setup, with the parts ready for robot pick-and-place:

Figure 3

Figure 3

In one of our Mydata My500 solder paste printers:

Figure 4

Figure 4

On the pick-and-place machine, with solder paste, but before any components are placed:

Figure 5

Figure 5

The parts plate in the machine:

Figure 6

Figure 6


With most of the components placed:

Figure 7

Figure 7

Through the reflow oven, prior to final inspection:

Figure 8

Figure 8

The final product, top view:

Figure 9

Figure 9

I abbreviated the process a bit, but those are the major process steps along the way.

Duane Benson
Happy birthday (month) Nikola Tesla

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Microbial Nanowires

Biologists at the University of Massachusetts-Amherst have genetically modified bacteria to produce tiny conductive wires that may one day be used in electronics.


Courtesy UMass Amherst

If we extrapolate this, does it mean that job-seekers won’t just have China and robots to compete with, but bugs, too?


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