Screaming Circuits: Industry


I'm a capitalist and I'm okay...

I'm a capitalist and I'm okay
I work all night and I sleep all day

300px-LaunchPad_wireframe Well, I don't work all night so much anymore. I used to.  I am a capitalist though. I think money is good (what some people do with it, not so much). And, I also think that when people make money, they should do so in such a way that others benefit as well. That's one of the reasons I like Ti's Beagleboard so much. Speaking of Ti, they have another microcontroller product that I'm excited about as well.

The MSP430 LaunchPad is a little development board designed for education in general as well as familiarization with the MSP430 line of microcontrollers for experienced developers. (I hope they don't mind that I'm using their picture on the right here. I don't have one so I couldn't take my own picture of it.)

A lot of companies have development boards for their chips. That's nothing new. But what is really cool is that they have set a retail price for this of $4.30. Yes, the price of a 16 ounce latte.

Now I know that a latte is important. Some people have speculated that civilization would collapse without caffeine. But, here's what you get in the place of that latte: (from the Ti website, again)

"For $4.30, the LaunchPad includes a development board, 2 programmable MSP430 microcontrollers, mini-USB cable, PCB connectors for expandability, external crystal for increased clock accuracy, and free & downloadable software integrated development environments (IDEs)"

Cool. I can explode one and still have another to finish the project with. I'm going to get me one of these and spend some time with it. I don't have any personal experience with the MSPP430 line, so it will be filling it's primary mission.

On the subject, I ran across an interesting website dedicated to the MSP430: www.43oh.com. If you're already a 430er or are just intrigued by the chip, go check it out.

Duane Benson
Buttered scones, anyone?

Need a Reference for the Reference

Not long ago, I wrote a short post about non-standard use of reference designators. After doing that, I've been looking at some of my own microcontroller and motor driver boards with an eye for how close to standards I am.

All of the R's, C's, D's and U's are okay, but there are some differences. For example, the Eagle library I've been using calls crystals "X" instead of the more standard "Y." I have seen crystals designated as "X", "Y" and "Q." LEDs seem to go by "LED" instead of "D" as indicated in the Wikipedia list. Headers go by "J", "JP", or "H." Wikipedia says "J" is for a female jack connector, "JP" is for jumper, and it doesn't list a "H." My board has break away two-row male headers and keyed single-row male headers. Wikipedia does note that its list is a set of commonly used designators. Not necessarily standard.

We probably do have the specific standards document laying around here someplace, and if I were doing real work on a professional basis, I'd hunt it down and make sure I followed the actual standards. But I'm not doing real work with my controllers and drivers, so I just do the best I can. I wonder how often that happens everywhere. The standards books are "somewhere" but no one really knows where.

Duane Benson
Somwhere over the reflow...

Electronics Shelf Life

Do parts and PCBs have a shelf life? Well, yes and no. I have some 7400 series logic chips in DIP form 7400 TH that I bought back in 1980. Every now and then, I pull one out and put it into a proto board to test some circuit idea I've got. They still work thirty years later. I haven't taken any special care in storage either. Some are stuck into anti-static foam. Some are not. All are sitting in a mini-parts bin without any moisture protection. I guess they do get a little shielding from light, but basically, they're just hanging out. They've been, at various times, in the attic, in the basement, in the garage or in the house.

That may seem like good evidence refuting a shelf like for parts. And today's parts are even more robustly Bent pins in strip designed to start with. Still though, if I use any of those parts, it's generally in a proto board or a socket. Sometimes I have to straighten the leads a bit. A lot of things don't matter so much at low temperatures, low speeds, low volumes and large geometries.

It's different when you have fine pitch parts being picked up and placed by a robot and then run through a 10 stage reflow oven. Oxidation that doesn't matter for a socketed prototype can interfere with the solder adhesion. Bent pins or missing BGA balls can prevent the part from fitting. Moisture absorbed over time can make the chip act like a pop corn kernel when in the reflow oven.

That's not to say that you can't use old parts for a prototype these days. Just give them a good inspection before sending them off for assembly. And, if they're moisture sensitive parts or have been stored in high-humidity areas, consider having your assembly house bake them before assembly. The same goes for raw PCBs too. Overly moist PCBs can delaminate during reflow. Some PCB finishes such as immersion sliver and OSP can tarnish or degrade over time too.

Duane Benson
Archaeologists, we are not

Modularity and Standards

Eons ago, (well, it seems like eons) when IBM designed its original PC, it took note of the success of the Apple II with it's modular expansion system - easily accessible card slots with loads of clear documentation - and added its own variety of modular expansion system. By doing so, the cost of accessories to consumers stayed low, the cost of installing or replacing said accessories stayed low and a whole new industry emerged to create compatible accessories.

Apple II I just read a Twitter Tweet ("Tweet" sounds too cutesy to me, so I'm never quite sure what to call those; maybe a "Twoot"?) from Mike Buetow that linked to an article about the latest Toyota recall. It seems that there are a couple of specific solder joints prone to cracking in the ECM (Engine Control Module) of certain models.

The last time I had any real data on the cost to replace an ECM, it was on the order of $1,500. Just scanning around the Internet, I found numbers ranging from $1,000 to $2,000. I'm guessing (I am speaking from near complete ignorance) that maybe two or three hours of that are labor at $90/ hour. That's a lot of cost in the electronics as well as labor hours that can't be used for billable hours. With so much of new cars being electronic, this issue is only going to become more extreme.

So, why can't the auto industry take a cue from the PC industry. Create a standard, easily accessible, electrical bus with standard, easy to manipulate mechanical attributes. Even if they were just standard within each manufacturer, it would still be a big improvement.

Consider this scenario: Buy a Toyota mid-size-car ECM at the local auto parts store. Take it home, plug it into a USB port on your home computer. It auto-runs a link to a specific web site. Enter your car's VIN number and the site loads firmware that matches the ECM to your car. Take the ECM outside, open your hood, flip a few latches on the water-tight electronics box, pull the old one out and plug the new one in. There you go. Done.

Instead of what is pretty much a massively expensive dealer-only operation, you have half a dozen standard bus ECMs to choose from and about 15 minutes of work that's not much more difficult than installing a new printer on your PC. And, you'd have less expensive aftermarket options as well. And, a new industry would emerge to design and build those aftermarket options.

Duane Benson
Sadly, not in my lifetime, Batman...

Global Shifting

Friday morning, I walked my way to the office in a slight drizzle. It was overcast and cool in the morning, eventually warming to near August temperatures later in the day. We had a long, mild winter, a long, cool spring and it looks like we're having a very short, not terribly hot, summer. Yet, the statistics (probably) don't lie. Global warming seems to be very real everywhere but here. The peat bogs around Moscow are burning, giant ice islands are breaking off of Greenland, and it's like 900 degrees over on Venus. All that, yet still nice and mild here in Oregon.

I think the same kind of things may be happening in manufacturing. By some accounts, it's all doom and gloom for North American manufacturing. We seem to be losing all of our manufacturing to other continents. But, maybe we aren't losing all of our manufacturing. Maybe it's just a shift. The high volume, low-value add stuff is likely gone, but to me, it appears that there's a thriving manufacturing industry for low-volume high-tech items. And not just in the contract manufacturing area.

There seems to be a re-emergence of small companies that are performing their own assembly in house too. They outsource what makes sense to outsource and in-source what doesn't. Adafruit and Sparkfun are two examples. The Arduino folks (in Italy) are building locally-to-them too. The Beagleboard from big-player Texas Instruments, is built in North America. Screaming Circuits and other small-volume companies like us seem to be doing quite well these days. Is it possible that the North American manufacturing industry isn't dieing, but is just changing? That's what I think.

Duane Benson
"Comet due to explode the earth at 9:42 this evening. Details at 11:00"

Reminders and Stress

Yesterday, I wrote about how much faster we can get things done in the prototype world than we could back when many of us were starting our careers. I mentioned that the decrease in time from weeks to days needed to re-spin a board and get a new prototype run completed is a double edged sword, but I kind of only mentioned the benefits - time savings, cost savings, quicker time to revenue generation. I didn't mention the down-side.

I also didn't really elaborate on another benefit - higher quality product. Instead of shipping product with PCBs riddled with mod wire, it's fast and cheap to get new boards and new assembled prototypes built and tested. These additional test cycles allow for much more reliable product. It can even improve the quality of firmware - shorter time to get a working prototype built means more time to write and test software/firmware. It's all good.

So, what is that second sword edge that I refer to?

RCA12ax7_sq_arms_smoke Stress. Yes. Stress. Back in the days before email and electronic projectors and speedy prototypes, we could relax more. A color presentation generally had to be sent out to have color transparencies or 35mm slides made up. If the boss wanted changes, they had to be made a week or so ahead of time. Now, with electronic projectors, changes can (and are too often) made at 2:00am the morning before the big presentation.

Since I can build you a prototype in a day or so, now those marketing geeks can, and do, throw changes in just a few days before release to production. Everything has to get done faster and faster. I want it now! We enable faster turns so the expectations increase and then we enable even faster turns and the expectation increase that much more. It never stops.

Duane Benson
Sorry. Sort of...

Reminders are Good Sometimes

I was just recently reading an article on another website that caused me to reflect a bit on where we've been and how far we've come in this industry. The article covered a design engineer's experience with modding a board back in the 80's and being required to ship the board with the mods instead of getting new ones made properly.

Back in the late 80's and early 90's, I worked for a company that designed and built business-oriented displays. One of the products was particularly troublesome to get going and the first production versions shipped with something like 24 different mods. If the company had re-spun the boards, we would have added at least a month to the schedule and payed somewhere in the range of $20,000 to $40,000 dollars. If I recall correctly, one of the biggest problem areas was the PLL (phase-locked loop). We were over-driving the parts a bit and that made all of the support passives and the layout that much more critical. Not smart, but I guess that came from one of those "cost-benefit" analysis type things.

Contrast that today where you can get a new set of boards from a PCB fab company like Sunstone.com in a few days for a few hundred dollars, get the parts from Digi-Key overnight and have us (Screaming Circuits) assemble them in a day or two.

Of course, it's a bit of a double edged sword. Like when faxes and later email came along. Written communications cycles that used to be measured in days became measured in hours and minutes. The expectations changed. Can you imagine writing a letter to a company and waiting a couple of weeks to get a response?!! That's the way it used to be.

In the same vein, us here at Screaming Circuits (and some other people too) have changed the prototype cycle expectations. Can you even imagine finishing your layout and having to wait four to six weeks for assembled boards to come back? Yikes! But that's what it used to be like. We're all making things go faster and faster. It keeps getting faster and it won't slow down. But that's good because time = money so less time building = less money spent and more time selling = more money earned. Right?

Duane Benson
I... Just... Need... More... Coffee... NOW!!!!

PCB Edge Clearance

In my continuing saga of answering the question "what are the real limits?", I'll spend a little time giving my thoughts on edge clearance. That makes the question for the day: "how close can I put parts to the edge of a PCB?" It's a good question but, regardless of what IPC says, surprisingly difficult to nail down.

The problem is that there are a number of valid answers all governed by the phrase "it depends." I'm not going to leave it at that though. I could. But I won't. Not today anyway. It really does depend on a number of factors, but I think it can be nailed down a little tighter than that. You've got to start by considering a few things:

  1. First, our old friend IPC-7351A does specify a keep-out area (AKA Courtyard Manufacturing Zone) on the part footprint. Keep stuff out of that area. This includes the board edge. Don't have any part of the component's keep-out area hanging over the edge of the PCB.
  2. Second, look at your PCB mounting arrangement. Make sure the keep-out area does not interfere with any mounting screws, and that includes any washers you may be needing. If your PCB mounts with slots or rails, make sure the keep-out area doesn't interfere with any of the rails or slots or case edges.
  3. Check with your manufacturer about their specific line limits. Many manufacturers have specific edge clearance limits based on their assembly line.

Now, take your application and consider those three items. Whichever gives you the biggest number is the Eagle_corner edge clearance you need to follow. Based on your mounting scheme, you may have different clearance requirements on different parts of the board. Still, make sure that for each section of the board, you use the biggest number from above.

Now, in the world of prototypes, things are a little different. At Screaming Circuits, we sometimes build up boards with parts right up to, and in some cases, over the pc board edge. You just have to ask yourself two questions for your prototype:

  1. Is there enough copper to give a good electrical and mechanical connection to the PCB?
  2. Am I likely to knock the part off the board with my handling?

If the answer the #1 is yes and #2 is no, then go for it. Of course, in the prototype world, you can always accept the risk yourself and go for it whatever the answers are. That's up to you.

Duane Benson
No worries. The green patches will burn off in the reflow oven.

IPC Says What?

I recently wrote about spacing, IPC standards and such. James M. commented on the post with a question:

"I run into this issue all the time. Assembly houses love to say that they can make anything that meets "IPC Standards for Placement" but when pressed no one can provide the exact number that gives this information. I know of IPC7351A, in fact I own a copy. And the keepout is clear there. But that doesn't influence things like component placement grids, how close things can get to the edge of a board, etc.... Are there other specific IPC standards that do?"

After reading James' comment and re-reading my post, I kind of realized that there isn't a lot of actual content in that blog post. Certainly not much actionable data. And, upon further thought, I think perhaps, all of us assembly folks kind of use that phrase "can make anything that meets IPC Standards for Placement" as a bit of a cop out. Not totally - we do have to set some limits on what we can build, but yikes! I've been trying to navigate the morass of different standard numbers (Maybe I should say "plethora" instead of "morass") and I don't know how anyone that doesn't specifically live the standards for a living could easily find those kind of answers. But us manufacturers really do owe it to our customers to come as close as we can to giving definitive limits that don't take a week of reading to interpret. I think I have to do this in stages.

First, we have three things: IPC-7351A for land patterns and IPC-A-600, covering the PC board workmanship. Then, we have IPC-A-610, covering our workmanship when we build and inspect the board assemblies. Those are the key standards that we live by.

There are a few other questions, such as edge clearances and things like that. I'll dig some more into that one later, but one thing to note is that for the Screaming Circuits prototype service, we don't require any edge clearance, nor do we require panels, rails or fiducials on our full-proto service. I hope this helps.

Duane Benson

Circuit Design ECOsystem

Years and years ago, I was a product manager at In Focus, the projector manufacturer. It was a great time to be in the display industry. New technology was being invented left and right (and center and back, and some over in that far corner too). Competition was still reasonably light and we were ahead of most of it.

It was always interesting to take one of the early overhead projector-style displays through airport security. Laptops were rare at the time, let alone a big clear display that looked like a see-through touch-pad computer, but without the computer. But that's not the point.

Back in our engineering department, we had the electronics engineers, a few folks to work on firmware, a layout specialist, documentation specialists to deal with all the documentation (duh), purchasing people to buy the parts and PCBs, technicians build up the prototypes, manufacturing people to get the pre-production and production going. And here,s the contrast today. Quite a few engineers I talk to these days have to do all of those jobs except final production. That wouldn't be too much of a problem except that while all of those jobs were being assigned to the engineer, everything got more difficult. Parts got smaller, timelines shrank, competition got more fierce, clock speed increased and a lot of formerly company functions, got out-sourced. It's a lot of work and a lot of ground for that engineer to navigate.

A couple of companies; Digi-Key, NXP, National Instruments, Sunstone Circuits and Screaming Circuits (my company), have gotten together to form the Circuit Design ECOsystem; a cross-company organization designed to help that design engineer get a design from inside the brain to the market.

NXP makes components and is creating library components for the CAD software made by National Instruments and Sunstone. Sunstone allows quoting and ordering of Screaming Circuits assembly service on their website and Screaming Circuits does the same with Sunstone PCB fab. Digi-Key is working to improve the data-flow to Sunstone's PCB123 CAD and streamline the parts procurement process to Screaming Circuits.

It's still early in the process, but the idea is to take the, now fragmented, design to manufacture process and make it easier for the electrical engineer to get through - to remove roadblocks, add in new services and improve communications to make it easier to produce a quality product.