Blog - Screaming Circuits


Do you Need that Part? Or, is it Just Habit?

At the moment, I'm working on an Arduino compatible clock. Like most of my Arduino compatible boards, this one uses an Atmega32U4, with USB built in. With the Atmega32U4, I sacrifice a little in program memory and SRAM, but gain a bit in reduced parts count.

A USB capable Arduino-compatible is, of course, programmed via USB, and can be powered by the USB port. Most Arduino boards also have a 5 volt regulator to be used when being powered by a wall-bug power supply. Naturally, I put the USB connector on the clock board, as well as the 5 volt regulator. With the two different supplies, I also put in circuitry to auto switch sources and protect the USB host when both supplies are connected at the same time.

NeoPowerSupplyMy first PCB revision required a few hand-mods, but not many. Still, I decided to re-spin the board and remove the two mod wires. While doing so, it suddenly occurred to me - a blinding flash of the obvious - that most cell phones and other small devices are charged with a USB-connector 5 volt wall-bug power supply. Why then, would I also need a separate power supply and on-board 5 volt regulator?

By pulling the regulator off of the board, I could eliminate a few capacitors and the supply auto-select / protection circuitry. Not only did I save in component cost, but I was able to reduce the PC board size, and thus cost, by about a third.

  1. I had the 5 volt regulator in the design because Arduinos can be powered by either USB or a non-regulated power supply.
  2. The reverse power protection is necessary to prevent damage to the USB host if the other power is also connected.
  3. The auto-power switching circuit is necessary so that a user doesn't need to flip a switch or change a jumper when changing power sources.
  4. I had two extra LEDs to indicate which supply was powering the clock.

I questioned my original assumptions, found a "because it's always done that way" and eliminated it. Assumptions are meant to be challenged.

Duane Benson
Question authority!
And then get squashed
(or, squash extra space out of your PCB)

Rossum's Universal Robots Month

I'm not sure who first used the term "drone", but "Robot" was first publicly used by Karel Čapek in his 1921 play "R.U.R.", or "Rossum's Universal Robots." January is not only the month the play premiered, but Karel Čapek was born on January 9, 1890. With that, Screaming Circuits is declaring January, 2015 to be Rossum's Universal Robots month!

RUR T-shirt mock upIn celebration of this momentous occasion, we've produced an exclusive "Rossum's Universal Robots month" T-Shirt. When the singularity comes, wearing this shirt will inform our new robot overlords of your support for their cause. Not that it will protect you or anything, but perhaps they will assimilate you with a bit more care.

Every customer who places an order before January 9, 2015, 5:00 PM, PST, will have the opportunity to get a Free "Rossum's Universal Robots month" T-Shirt, designed by local graphic artist, Kyle DeVore.

Look for instructions via email on how to get a free T-shirt after your next order (provided the order is placed between today and on or before January 9, 2015). If you place an order between now and then, and promptly respond to the email, you can get one for free.

But, what if you don't have anything to order? Well, you can still celebrate our impending doom at the hands of our own creations by buying the T-shirt from our page on teespring.com [Click here to buy on Teespring]. We don't want grease money, so we're selling them on teespring at our cost.

Robot revolutionDuane Benson

Poor Alquist ceded care of the world to Primus and Helena.
He set off on a hopeless search to find any last human survivors.
To no avail, he searched the seven continents and the seven seas.
Until at last, he saw beings, not robots, on a small island near Sumatra.
Poor Alquist, being not a newt, was never again seen on land or at sea.

Chips Making Faces

Chip face

Not too late for a Screaming Circuits electronics business card holder

In November, we started our electronic business card holder program. We ended up building more than we had planned, so it will be available for December as well - at least until we run out.

Business card holder top viewHere's how you get one: If you're an existing customer of ours, we’d like to share with the world, and with our production floor, a little about you. Us marketing folks keep a close eye on what you need, but it's more difficult for the people a little further from the phone to do so. Little videos help.

Send us a short video - somewhere around 30 seconds to 2 minutes - about who you are and what you do. No need to worry about equipment. A cell phone video is fine.  If you send it in before we run out, we'll send you a free business card holder.  We only have 40 of this limited edition available so submit your video today! 

Here's the rules:

  • Must have ordered from us to submit an entry.   
  • You can use any video recording device (cellphone or video camera)

Still not sure if you need one?  Watch this video. 

Who Are We?

People sometimes ask who we are as Americans, or who we think we are.

We are a diverse lot. We are people who couldn't hack it in the old world. We left the old world because we were chased out, kicked out or kidnapped out. We left the old world because we saw opportunity to be free or the opportunity to exploit. We left because we didn't fit in or didn't like the life open to us. Some of us were here first and weren't able to fare well against the newcomers. Some of us escaped the old world because we simply wanted better. We are a mixture of everything that we don't like about the world and of everything that we do like about the world. We are an amalgam of all that is good an all that is bad. We are proof that when you mix good and bad together, the result is more good than bad.

We are a symbol. We are a symbol to the world that you can change governments without violence. We are a symbol that individuals really do have a voice and a choice. We are a symbol that opportunity for the human spirit still exists. We are this for two reasons: people are willing to dream for it, and people are willing to die for it.

Today is a day set aside in this country, for us to thank those that have been willing to die for it. Without them, the dreamers would never have more than a dream.

Images

New Electronic Screaming Circuits Business Card Holder

It isn't easy to differentiate yourself from the rest of the world.  Use this electronic business card holder to impress your peers and customers. And well, it's just plain cool.  

BizCardHolder

If you are an existing customer of ours, we’d like to share with the world a little about you.  Submit a 30 second to 2 minute video about who you are and what you do.  If you are one of the first 40 entries, you will receive a free business card holder.  We only have 40 of this limited edition available so submit your video today! 

Here's the rules:

  • Must have ordered from us to submit an entry.   
  • You can use any video recording device (cellphone or video camera)

Still not sure if you need one?  Watch this video. 

Freescale KL03 and PCB123 at 0.4mm pitch

Small component packages seem to be a recurring theme with me. It's understandable, I guess. Super tiny packages are becoming more and more common and we build a lot of product with them.

The smallest we've built is 0.3mm pitch. Those aren't common enough to be considered standard - they're still an experimental assembly - but not many chips use them yet. 0.4mm, on the other hand, is something we see on a pretty regular basis.

What's so tough about that?

The biggest challenge with these form-factors seems to be footprint design and escape routing. I can see why. There really isn't room to follow any of the standard BGA practices. You can't fit escape vias between the pads and you can't put vias in the pads, unless they are filled and plated over at the board house. Filled and plated vias are the easiest way to go, but it can make for an expensive board fab.

KL03 WLCSP20 on a US Lincoln Penny

1-DSC_0008One of my side-projects involves trying to make the smallest possible motor driver. For this project, I've chosen the Allegro A3903 driver. It's a 3mm X 3mm DFN (dual flatpack no leads) with 0.5mm pitch pads and a thermal pad in the middle. The microcontroller will be the new Freescale KL03 32-bit ARM in a 1.6mm X 2.0mm WLCSP (wafer level chip scale) package. It also comes in a 3mm X 3mm 0.5mm pitch 16 pin QFN. Without an expensive PCB, that may be my only option.

Pick your CAD package

I'm using the newest version (5.1) of Sunstone Circuit's CAD package, PCB123, but the principles here will apply to any CAD software. If you don't already have a copy, download PCB123 V5.1 here.

If you've got fast Internet, you're done now, so go ahead and install it. You'll need the manual too, which you can get here.

I need to eat now, so stay tuned for Part 2.

Duane Benson
Nerfvana - It's like Nerdvana, but with more foam darts.

VTP - Very Tiny Parts

FreescaleKL03A while back, I wrote about a new ARM Cortex M0+ chip from Freescale. It's not the first M0+, but I do believe that it's the smallest. I've been checking stock off and on and finally found the smallest package to be in stock and available to ship.

I actually bought a couple of different types. First, there's the WLCSP 20. It's got 32K FLASH, 2K SRAM and an 8K bootloader. The real kicker is that the package is only 1.6mm X 2.0 mm. I also got a few in the QFM 16 package, which is a bit more workable at 3mm X 3mm.

Finally, I bought a Freedom development board with th 4mm X 4mm QFN 24 package. The dev board is hardware compatible with Arduino shields, so that will make for some interesting possibilities.

Anyway, here at Screaming Circuits, I'm most interested in that 1.6mm X 2.0mm package to see how easy (or difficult) it is to use - see if there are any particular layout challenges. The other stuff is just for after hours play time.

Duane Benson
I'm not a number. I'm a free development board!
(Free, as in named "Free...", not free as in "don't cost nothin")

Cost Reduction in Design - More Advice for Makers

If you're looking for the absolute, cheapest possible assembly service, you'll need to look outside of North America. If you really need a decent price with good quality and good service, you can keep your gaze West of the Atlantic and East of the Pacific.

Like everything else in the modern world, design decisions can have a pretty big impact on your cost. So, lets take a look at some design decisions that can make your manufacturing more affordable.

  • Accept longer lead times

Lead times are one of the biggest factors in electronics manufacturing. Screaming Circuits can turn a kitted assembly job overnight, but it costs a lot of money to do that. Screaming Circuits also has a 20 day turn-around that is much, much more affordable. Accepting longer lead times on PCB fab will drop your cost as well.

  • Avoid leadless packages like QFNs and BGAs

We build tons of QFN and BGA boards - even down to 0.3 mm pitch micro BGAs. That's great if you need those packages. However, since all of the leads are underneath, we have to x-ray every part. That adds a bit of cost to the process. If you can, stick with TSSOPs and other parts with visible leads.

  • Use reels, or 12" or longer continuous strips

Tab routed multi panel 1024We will gladly assemble parts on strips of almost any size. But, to save costs, use full or partial reels or continuous strips of at least 12" long. It costs us less time to work with reels and continuous strips, and we pass those saving on.

  • Stick with surface mount

These days, thru-hole components tend to be hand soldered. That costs more than machine assembly, so use surface mount wherever possible. Surface mount components tend to be less expensive than thru-hole too. If you do need a few thru-hole parts, this is an opportunity to put in a little sweat equity by soldering the thru-hole yourself and save a bit of money.

  • Panelize small boards

We can work with really tiny boards individually, but sticking with a larger size makes the job easier, and, again, we'll pass those saving on. If your PC board is smaller than 16 square inches, panelize it. We put in less labor and you get a price break.

By sticking with Screaming Circuits, you get the same care and quality that we give to boards going up into space, down into the ocean, and everywhere in between. By sticking with Screaming Circuits, you get a known turn-time; not an "about ..."

By following these guidelines, you get a decent price and really good quality and service.

Duane Benson
That would be telling

Choose Your Package Wisely

As I mentioned in my prior blog, there are reasons to consider different packages than just physical size.

Sometimes it is just space available on the PC board, but there may be other considerations as well. One of the first to consider with really small size packages, is the capability of your manufacturer. Not all assembly service providers can TI ESD CSP 007 croppeddeal with super-duper small parts.

That's a paperclip next to the little ESD protection chip in the photo on the left. At Screaming Circuits, we can go down to 0201 passive parts and 0.4 mm pitch BGAs. We've even done a few 0.3mm pitch BGAs, but those are pretty rare still.

Some manufacturers stop at 0402 (or even 0603) parts. If that's the case with your manufacturer, then you'll need to eliminate sizes smaller than their limit (or find someone else to build the board).

Cost might also come into play. It probably won't be enough of a factor to worry about during prototyping, but it may be worth looking at for volume production. Sometimes the smaller form-factors add cost. Sometimes the part value you need may not even be available in the smallest packages.

TI TPS62601 front and backIf both cost and size are significant drivers, weigh the cost savings from reducing the PC board area against any additional cost with smaller packages.

Noise can factor into your package choice too - especially regarding bypass capacitors on high speed chips. You want your bypass capacitors as close to the power and ground pins as possible. The higher the speeds, the more important this is. Dropping your package size down to 0402 or 0201 can make it easier to put the caps closer to power and ground pins.

Duane Benson
You don't need to ask Alice because your parts aren't ten feet tall