Author Archives: Duane

About Duane

Duane is the Web Marketing Manager for Screaming Circuits, an EMS company based in Canby, Oregon. He blogs regularly on matters ranging from circuit board design and assembly to general industry observations.

Is Geek Cool?

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When I was young, “geek” was not cool. Neither was “nerd.” Working on cars was cool as was logging and shooting Bambi’s uncles with high-powered rifles, at least where I came. On the other hand, every little town had a Radio Shack where you could buy tubes, transistors, ICs and other assorted electronic components. You don’t see that so much anymore. Grocery stores sold publications like Byte Magazine, 101 Electronics Projects and Radio Electronics. Those magazines were about building things. People who read and wrote those and others like them created an industry in their garages, basements and bedrooms. They started a new Industrial Revolution.

Still, back then, tech folks were more likely thought of as mad monks and strange people like Eddie Deezen as “Mr. Potato Head” (Malvin) in the 1983 movie War Games. You didn’t want to be one. I like to think that attitudes have changed over the years, and I think the signs are there.

The FIRST Lego league with its robotics tournaments has created a legitimate “sports like” atmosphere for geek-types in school. 50,000 plus Arduinos being sold shows that the electronics hobbyist world is moving again like it did in the 80s. The maker and bender communities illustrated by Hackaday, Makezine and supported by companies like Adafruit and SparkFun show that creating with chips is as alive as it was in the late 70’s and 80’s. TV shows like Mythbusters, Jimmy Neutron and Prototype This have glorified the geek.

And why do we care? Because the more engineers we build out of the masses, the better we can design and build our economy. The more mainstream and acceptably technology is, the more educators will work to encourage and foster the environment and attitudes that allowed Apple, Dell, Google and SparkFun to thrive. We need that. We need robotics competitions to be as socially acceptable as football games.

Duane Benson

The rooms were so much colder then

http://blog.screamingcircuits.com/

Parts Too Close For Comfort

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Another tale from the sometimes kind of kooky world of prototypes. I think what happened here is that the board was originally laid out for caps with a smaller voltage rating (or even a smaller capacitance value). We’re seeing things like this more often these days due to availability issues. The part gets swapped at the last minute because the exact one is out of stock. Operationally, it won’t hurt and if the board had been laid out with more space, this wouldn’t have caused any issues at all. Of course, then, it may not have fit in the box.

The moral of this story is that with last-minute swaps, don’t forget to double check things like the part package and board spacing. This board works fine, but it won’t be meeting up with any IPC standards as long as these parts are like this.

Duane Benson
Parallel parking is hard. I’d much rather diagonal park.

http://blog.screamingcircuits.com/

Another Land Pattern Mixup

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Here’s an interesting error that doesn’t show up very often. Notice that the opening in the solder mask matches about what the copper land pads should be, but the pads themselves are really tiny. To start with, it’s not an exact match. It would fit the part a little better if the pads were closer together, but more than that, the pads are just the wrong size. The stencil looks okay and the solder mask opening looks okay (except that it’s a little too too wide).

I’m not really sure what went wrong here. Maybe one person started making a custom library part and someone else finished it, or maybe the component was changed between starting and finishing the library part.

If the stencil photo looks like it’s made of cloth — it’s not. We just photographed a CRT view of it.

Duane Benson
Need more chocolate.

http://blog.screamingcircuits.com/

Close Only Counts …

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I think this one has both some land pattern issues and some schematic issues. It’s unfortunately pretty common to see footprints that are close, but not close enough to work. Looking at the data sheet here, there may be a schematic issue as well. The only connections on to the part on this board are ground and P3. I don’t know the part, so I suppose it’s possible that all it needs is P3 and ground, but it looks more like a case of the footprint being wrong and the pin connections being wrong. Pins 1, 2, 3, 5 and 7 are all ground, but on the board, 1 and 3 go some place else. Bummer.

Making custom CAD parts can be pretty annoying and it seems to be a function disproportionately prone to error. Why is that?

Duane Benson
in horse shoes, hand grenades and sometimes atom bombs

http://blog.screamingcircuits.com/

Than Thara Wara Nona

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I recently received an email comment about my blog writing that I think does a very good job of illustrating one of the frustrations that many design engineers face.

“Please have someone teach Duane the difference between “then” and “than”. It really makes him look dumb, and I very much doubt that Duane is dumb. It’s just painful see these everywhere in his blog. regards“

I’ve also been called out on “it’s” vs. “its.” At least, I seem to mostly have the “to”, “too” and “two” down. Now, I’m a reasonably educated person and writing is a significant part of my job, so you would think that I wouldn’t fall into traps like this. Undeniably, I do. It drives me nuts. I even have a couple of websites that I refer to (when I think about it) to help with such things. Site one and site two, but obviously I still fall into the traps.

So, how does that relate to the frustrations of a design engineer? Well … read my blog. Most of my writing is about a very similar issue. Check this one about via in pad. And this one about parts libraries. Or this one about shorting potential under a QFN.

None of those problems was created by “dumb” people. Likely, all those boards were created by intelligent, highly skilled, well-trained engineers — people who got picked on in school for blowing the curve, or were called “Spock” by kids not on a college track. Yet, what does such an error get? It may get a blog post here. It may get a Twitter comment like this that I wrote about. Of course, some times silly little oversights like this have more dire or more expensive consequences.

And the moral of the story — attention to detail and continuous learning. Never stop trying to learn. Never stop double-checking. I have to refer to my two grammar sites and other references. If you’re a designer, never stop researching. Dig into those data sheets. Read up on best practices. If you’re working a job over multiple sites, always make sure everyone’s using the same rules.

Over the next few days, I’m going to go back through my past posts and see how many of these “than/then” errors I can find and rework. Ugh.

Duane Benson
Never give up. Never surrender.

http://blog.screamingcircuits.com

My Top 10 Electronics Predictions for 2010

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Yeah, yeah. Top 10 predictions for the new year really need to be out in either the last week of the prior year or the first week of the new year. But I’m late. It’s because my oatmeal is lumpy and I’ve just been trying to decide if I should have a top predictions for the new year or for the decade. Some people would say that we’re still in the old decade, because, you know, 1 – 10. But I say, it’s only analog jockeys that say that. Digital drivers go from 0 – 9 (or 0 – 1 or 0 – F or 0 – 7… now I’m confused again. Not many go 0 – 7 these days). For the purposes of this document, I’m claiming to be more digital than analog, so the new millennia started in 2000 and this new decade starts now. Or, does that mean that the new millenia should start in 2048? Or, rather 0x800? Crud. That’s not a thousand. Okay, I don’t want to wait until 4096. I might be dead by then. Fine. It’s the year 3732. I have my handy 74LS90 and I’m going to count out my top 10 predictions.


Starting at count 0, with Qa = L, Qb = L, Qc = L and Qd = L:

0000: By the end of the decade, 50% of all passives will be embedded passives and 20% of all PCBs will have 90% or more of their passives embedded.

0001: By the end of the decade, Quad stack POP (package on package) will be commonplace.

0010: By the end of the decade, Each individual human will have their own IP address. Several of us will have more than one. That way, we can jury rig accelerometers into our hands and feet so we can wirelessly know where each of our extremities are at all times. Cats will have them too.

0011: By the end of the decade, solder paste will be used less often than not when assembling components on to PCBs.

0100: By the end of the decade, nearly all hydraulics and pneumatics in new motor vehicles will have been replaced by electrics.

0101: By the end of the decade,the first semi-autonomous passenger vehicle will be on display on the auto-show circuit. Hobbyist built semi-autonomous cars will already be on the road.

0110: By the end of the decade, “airline pilot” will generally be a really, really, really boring job. That’s a bit of a problem.

0111: By the end of the decade, most military “foot action” will consist of two soldiers in command of a squad of robots and those two soldiers will as likely be in Fort Lewis, Washington as in the combat zone.

1000: By the end of the decade, the president of the US will be promising health care reform as the highest priority.

1001: By the end of the decade, routine bioengineering will be, well, routine. Very scary.

1010: By the end of the decade, the 2019 recession will be looming large and all of the people that have forgotten about the 2009 recession and the 2001 recession and the 1985 recession and the 1975 recession… will be freaking out again.

1011: By the end of the decade, lead will be gone from 98% of new electronics. Bummer.

1100: By the end of the decade, four of the substances that replaced the substances removed from electronics due to ROHS and similar regulations will have been found to be significantly more harmful to the environment and the people recycling the materials than are the substances that they replaced.

1101: By the end of the decade, the world of intellectual property will be in even more of a mess than it is today. Virtually everything will be accessibly for easy theft and cheap replication. (This is pretty much a big “duh.”)

1110: By the end of the decade,building your own mutli-purpose robot will be as easy as building your own PC was in 1988. Hardware components and operating systems will be off the shelf, but standards will be pretty loosely defined, interoperability will be more theory than reality and applications will be sketchy and buggy.

1111: By the end of the decade, still no flying cars and personal jet packs, dadgummit!

Duane Benson
Sorry. I didn’t have a 74LS90. I only had a 74LS93

http://blog.screamingcircuits.com/

mbed Development – USB Programming Forever

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I’m still fiddling with my mbed. Although, I haven’t put it to real use yet. I’ve got some ideas, but I just don’t have the time these days. One of the nice things about its programming system is that if I do have to step away for a while, it’s easy enough that I don’t have to go through any kind of learning curve again. The plug-and-go USB programming and online IDE is that easy.

Contrast that to one of my little PIC based boards. I recently wanted to do something with one that I hadn’t used for a while. I dug it up and pulled out my programmer. I somehow ended up with two different versions of the programmer software installed on my computer, and I had to try both. My programmer uses the FTDI USB/serial chip, so I had to try and guess which COM port to set my programmer software too.

Six permutations later, I had that figured out. I then loaded up an old known-working hex file and took my best guess at what the fuse settings needed to be and guessed wrong. Tried again and guessed wrong. Tried a dozen different combination and gave up and dug up the PDF of the data sheet. Once I found the setting and translated them to the language used in my programmer’s software, I finally figured it out and got it all working.

Granted, if I were using this every day, I wouldn’t have forgotten all those silly little details, but think about someone learning for the first time. Or, consider a hardware engineer that rarely uses microcontrollers. Once a year or so, some design does need a controller and some programming. I’m a big fan of PICs, but the programming system for many of them seems pretty archaic compared to a product like the mbed.

Duane Benson
I need gravy for the mashed potatoes in yesterday’s post

http://blog.screamingcircuits.com/

Ambiguous PCB Markings

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Here’s a little issue we run into now and then. Which reference designator goes with which part? Quick. I need to know. Now. Now. Now!

It’s less of an issue with SMT parts because we machine place them and use your centroid file to do the programming. Still though, It’s always good to have things marked clearly in case rework is needed and for visual inspection.

For through-hole, though, it is definitely an issue because a real human being is putting the parts in and the visual markings are the programming for the human type person.

For best results, take a little extra time and make sure all of your ref designators are clearly associated with the correct part. It’s also always a good idea, when possible, to have all the designators in the same position relative to their part. Consistency is a good thing here. Consistency is a good thing with mashed potatoes too. Who likes lumpy mashed potatoes?

Duane Benson
You say poe-ta-toe, I say ugly brown tuber

http://blog.screamingcircuits.com/

Microcontroller in the Middle

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I’ve written about Open Source hardware before, such as the Beagleboard and Arduino. Those are both great options for folks needing to get moving on embedded microcontroller development.

The Arduino is pretty low-end and the Beagleboard is pretty high-end. I think I’ve run across a good step right in the middle.

A while back at the ESC show, we spoke with a gentleman from ARM about a project that would include an online IDE, and now, here it is. It’s not exactly the same as open source, but it solves many of the same problems that open source solves. Mainly, it’s a quick and easy way to get up and running with an ARM processor. Well, it looks easy, anyway. I haven’t tried it yet. I think I’ll see if I can get one and give it a shot.

By the way, we did not build this board. We have built some Beagleboards, but not this particular product. It certainly wouldn’t be a problem for us, but that’s not why I’m writing about it. It just looks like a great halfway point between something like the Atmel-based Arduino (or the PIC microcontrollers that I use) and the Beagleboard that uses the super-speedy ARM Cortex-A8.

If I can run one down and find the time to fiddle with it, I’ll let you know what I think of it in actual use.

Duane Benson
Stay tuned. Bulletins as event warrant.
Maybe …

http://blog.screamingcircuits.com/

Oxidized PCB Finish

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I’ve written a few times about potential and actual problems with different PCB finishes. Sometimes, the results are tragic and sometimes, just annoying. I’m not sure where this one falls on the continuum between the two extremes, or maybe even outside. I suppose it depends on who’s paying the bill and how close these need to be to a final production product.

The surface on the pads had been exposed to the elements a little too long such that, even with good flux, the solder balled up instead of adhering as it was supposed to.

PCB finishes are more robust then they were even a few years ago, (although, a few years before that when we were mostly using leaded HASL, things weren’t so bad) but still, your raw boards should be treated more like food then like shoes. Avoid fingerprints and other contaminants. Try to use them promptly. Store them properly. If your air quality is poor, be even more cautious in your handling and storage.

Duane Benson
Let not the sands of time get in your lunch

http://blog.screamingcircuits.com/