Blog - Screaming Circuits


What's In Your Way?

If you're attempting to cross the median of a busy four-lane highway, it's entirely possible that there's a Jersey Barrier in your way. In that particular setting, having something sturdy blocking your way is probably a good thing. On the other hand, I would bet that, for the majority of you reading this, there are some barriers around you that you'd much prefer not to run into.

Jersey barrier dimensionsBarriers can bring on stress, uncertainty, risk, and a general sense of despair. Despair can lead to hopelessness. Hopelessness can lead to you being rolled up in a fetal position under your desk, tangled up in the nest of cables that every good engineer has under their desk. As everyone knows, if you're under your desk tangled in cords and whimpering when your boss walks in the room, you're probably not going to get a Christmas bonus.

That's where smart outsourcing can help. We talk about PCB Assembly as being our thing, but conceptually, it's more of a case of us trying to remove some of your barriers. We'd prefer that you get your Christmas bonus rather than getting carted off on a gurney, too afraid to open your eyes for fear of the glare of your abandoned co-workers.

Here's what we suggest:

  • Spend a little extra time on design review to increase your confidence (ever find an overlapping trace the day after sending the design out?) 
  • Double check that your BOM and or parts kit is current (If you chose the parts a few weeks ago, some may have gone out of stock)
  • Drink some water (dehydration can interfere with a clear, logical thought process)

If the extra day or two doing so causes a problem, just order a faster turn-time.

Duane Benson
129 °F in June of 2013?!
Well, what did you expect from a place called "Furnace Creek"?

No need to waste parts

We love parts on reels. Who doesn't? But reels aren't always practical - and it's not just about cost. Cost is, of course, important, but there may be other factors to consider.

Say, for example, you need 20 2.2K Ohm, 5% 0805 resistors. You could buy a small strip of 25 from Digikey for $0.32. That gives the 20 you need, plus a few spares just in case.

Alternately, you could buy a digi-reel ( a custom quantity reel). On the reel, you'll probably want more parts to keep the strip long enough for the feeder. Let's go with 250 parts for $1.39. Digikey charges $7.00 extra to create a custom reel, so that's a total of $8.39. Still peanuts.

For a third choice, you could just buy a full reel of 5,000 for $10.64. Still peanuts. If you're gong to need the same part for a lot of designs, this might make sense. But, there's more than just cost to consider. You need to store and ship it. Shipping two dozen reels gets pretty expense. Storing and inventorying several dozen reels can become a hassle too.

Cut strips on plateThe beauty of Digikey, Mouser, and other places that sell cut strips is that they essentially become your parts warehouse. You pay the $0.32 cents and never have to worry about whether the part is in your inventory, how many are in your inventory, digging it out of wherever you stuffed the reel when you last needed it...

If you do buy and store the whole reel, you don't need to ship the entire reel to us. Just cut a strip with the number you need, plus about 5% for that "just in case."

Of course, if you need a few thousand of the parts, go ahead and send us the reel. It would make sense then.

Duane Benson
Reel, reel your part
Solder it, solder it, solder it, solder it
Cost is but a factor

Packing Parts for Personal Manufacturing

Manufacturing, especially small volume one-time-only builds (like a prototype) is hard. It's not wise for most people to actively seek out chaos, but that's what we do, and we do it wisely. That's what we've been doing since 2003. 

We do it because it's hard and because it's necessary.

A big part of quality manufacturing involves risk reduction. Prototyping and quick-turns inherently add in a lot of risk. While we've designed our processes and systems around turning that risk into a quality product, there are a few things that you, the customer, can do to help reduce risk even further.

One of the best things you can do to reduce risk is to prepare a well organized kit, as shown in this video.

 

You can send us your parts in short, cut strips, like you get from Digikey or Mouser, long continuous strips, full or partial reels, tubes or trays. We machine place from all of those types of packages. What's important is clear labeling and organization.

Individual, or mixed/loose components are not good, though. Pins get bent, leads get contaminated, values get mixed... Leave them in the strip, even if it's short. If you've got multiple short strips of the same part, we can still machine place. Don't tape them together. We can deal with them as is.

Duane Benson
Peter Piper Picked a Peck of Pickeled Manufacturing

Proper PC board storage - The top three hazards

It's late. Do you know where your PC boards are? Let me rephrase that: Can unused PC boards be stored for future use?

Yes, they can - if stored properly. Keep them wrapped up, or sealed in a bag. Anti-static isn't necessary in this case, but it won't hurt. Keep them in a cool, dark place. Keep them clean. Do your best to avoid dropping them on the floor and stepping on them.

The board in this photo was left out on a desk for a while, and then shoved into a desk drawer. The environment took its toll on the immersion sliver finish, making it very much unusable.

Old Beagleboard

What can go wrong:

#1: Fingerprints: The oils on your finger can etch your fingerprints into ENIG or immersion silver PC board surfaces. If you plan on committing a crime, go ahead and do this so we can catch you. If you aren't going to start a life of crime, be careful to not get your fingerprints on the board surface. Handle on the edges, or at least, don't touch any exposed metal.

#2: Moisture: Moisture is good for your skin, but not for your PC boards. Over time, PCBs can absorb moisture, especially in a humid location, or the ocean. If thrown into a reflow oven, they then might laminate. Do your best to store boards in a dry environment. If stored for a long time, you may want to pre-bake them prior to use.

#3: Atmosphere: Sometimes dirty air can contribute to tarnish or corrosion on the exposed land pads. Dust can settle onto the boards as well. Tarnish and dust can usually be cleaned off, but corrosion can't. Wrap up your boards for long-term storage.

Treat your boards well and you can likely use them at a later date. Don't treat them well and you may need to replace them, wasting a bunch of money. Often, the damage isn't as clear as in the above photo, but could still lead to poor solderability.

Duane Benson
Don't surf on your silver

What is Personal Manufacturing?

There's a lot of buzz floating around these days, about "Personal Manufacturing." Screaming Circuits has more than a decade of bringing personal manufacturing to engineers. We pretty much started the category in the electronics industry, so we're quite familiar - but not everyone knows what personal manufacturing is. I'll do my best to describe it, and what it can do for you.

The short answer, is that personal manufacturing is building your boards on your terms, not on the terms of some nameless, faceless factory.

Vertical_markets
The longer answer is probably more useful. 

Traditional manufacturing is all about statistics and fractions of a penny. Those factors are important; especially if you're manufacturing millions. But, when you just need a few boards, or a few hundred boards, those factors can make your job nearly impossible.

With personal manufacturing, you can decide when you want or need assembled boards on your workbench. You won't need to beg for time on a busy volume manufacturing line. In the case of Screaming Circuits, it's cloud-based manufacturing so you can order online from your desktop, when you're ready, rather than waiting for someone to pick up a telephone.

With personal manufacturing; you design it, get some prototypes, make a few mods, lather, rinse, repeat. Then, you'll get a few dozen, few hundred, or few thousand, and start selling. You'll get what your budget allows and don't need to commit to minimum volumes, or long-term business. You can polish your design faster, with less hassle, and you can get to market faster, with less hassle. Faster to market and less hassle both mean more time and money for you.

NPI (new product introduction) has never been easier than it is with personal manufacturing. Years ago, I was a product manager at a start-up. The entire NPI process was a nightmare. Our engineers couldn't get anything built without half a dozen support staff. Someone had to make the documentation usable. Someone had to hunt down sample quantities of parts. Someone had to make sure the board would fit on the volume manufacturers' assembly line. It went on and on like that, taking up months of the design cycle. We were at the mercy or people who only cared about making their part of the process easier.

Rather than producing the quality product we wanted, our new products would be shipped to customers with mod wires. I recall one board that needed 64 mod operations before it could be shipped. Yes, that was on a released, shipping product.

With personal manufacturing, as Screaming Circuits provides, you can get a few prototypes built right away. If need be, you can modify, and get a few more built at your convenience. When the mode wires are gone, you can build up a hundred and get them out to customers without delay. It's not about what works best for Screaming Circuits; it's about what works best for you.

Duane Benson
Right now a personal pan pizza delivered to my desktop would work for me.

 

 

Manufacturability Index in practice

My prior blog covered the Screaming Circuits Manufacturability Index. It's something I'll be using from time to time when discussing new components I run across. I've got a few examples to put the numbers into context.

On the low side of the index, we have:

7400 TH1: Just about anyone could hand solder the part
Examples: Thru-hole parts

The SN7400 quad NAND Gate, shown on the right, is a good example. It's big, it's thru-hole, and if someone has trouble hand soldering it, they really need a few more classes.

Closer to the other end, is a new chip I've run across. The Silego GPAK4 is a small FPGA-like mixed signal device. It's got a number of analog peripherals, a bank of programmable logic, and the ability to configure it up the way you want. Take a look at it below:

GreenPAK4 cropped

This little thing is housed in a 2 mm X 3 mm QFN package. That's pretty tiny by the standards of my giant fumble-fingers. I've given it a rating of 4.b, on the Screaming Circuits manufacturability index. The number ranking "4" means: "Needs advanced automated assembly technique", and the letter suffix "b" means: "Typical level of challenge within the number rank." In other words, right up our alley.

Unless you posses super-human abilities, and maybe lasers in your eyes, you won't be hand soldering these. You'll have them assembled by us (or someone with the same technical capabilities as us), where it will be a standard process.

If you do want to put one or more of these in your design, you will want to make (or find) a custom library footprint for your CAD software. Due to the variable length pads, a standard one-size-pad footprint might lead to solder joint reliability issues.

Duane Benson
The chips go marching one by one, hurrah, hurrah
The chips go marching one by one,
The little one stops to suck her thumb
Just to see if the solder is lead-free

 

Screaming Circuits Component Manufacturability Index

Screaming Circuits Manufacturability Index

Ranks the difficulty of assembling a component. Index is one to five, with one being easiest, and five being the most complex

Sub index: a, b, c

    a: Not a challenge within the number rank
    b: Typical level of challenge within the number rank 
    c: Fits in the ranking, but likely needs special process, fixtures or attention

1: Just about anyone could hand solder the part
Examples: Thru-hole parts

2: Surface mount. Should be machine placed, but big enough to hand solder
Examples: 0805 or larger surface mount passives, SOIC packages

3: Pretty much any grade of surface mount equipment can handle this component
Examples: TSSOP or larger, 0.8mm pitch BGAs

4: Needs advanced automated assembly techniques
Examples: 0.4mm pitch BGAs or QFNs, CSP (chip scale package) or WSP (wafer scale package) BGAs, 0201 size passives, Package on Package (POP)

5: More or less R&D at this point. Few companies have or will assemble this part
Examples: 0.3mm pitch micro BGA, 1,700+ ball BGAs, 01005 passives

Just about everything 4b, and below are routinely within Screaming Circuits standard (guaranteed) process. 4c, 5a, 5b, 5c, are becoming more common here. These are special process (falling outside of our guarantee), but we can usually do a good job with them. You'll need to speak with a manufacturing engineer before placing the order.

Duane Benson
a colossal negative space wedgie of great power coming right at us at warp speed
Readings are off the scale, captain

Mark Those Diodes!

MarcoPOLOLogo5Every now and then, I write about ambiguity with diode marking; like here, here, or here. It's a pretty important subject to get right, but what does it have to do with Marco Polo, you ask? Well, that depends on whether you're asking about the person or the game.

In the game, people try to find someone, without sufficient information. One person, designated "Marco" closes their eyes and periodically yells out "Marco." The other people respond with "Polo", and the Marco tries to find one of those other people with just the audible cue. For some critters, that's an easy task, but for the average human it's not always so easy - especially when the diode doesn't audibly respond to "Marco."

If you're talking about the explorer, Marco Polo; well, he set off on an adventure, got lost, and either saw a bunch of cool stuff, or made up a bunch of cool stuff (depending on whom you ask).

Again, you ask... "What does this have to do with hamburgers in a handbag, or with diodes?"

It has to do with the fact that he didn't know where he was going, and, that without clear marking, it's not always possible to know which way to point the diode.

BlackPOLOSo, we're celebrating Marco Polo month with our Screaming Circuits Marco Diodo Polo shirt.

If you place an order with Screaming Circuits during May, 2015, we'll send you an email with instructions telling you how to get a free Marco Diodo Polo shirt after your next order (provided the order is placed between May 1, 2015 and on or before June 5, 2015). If you place an order between now and then, and promptly respond to the email, you can get one for free (a shirt. Not an order).

Duane Benson
Fifty-four fourty, or fight!

Via in Pad - Why and How

There are many reasons you shouldn’t use via in pad. It’s not good practice, and those via holes act like BGA via in padlittle capillary straws and suck solder off of the pad or the BGA.

That said there are some applications that may require, or seem to require, via in pad. Here are a few examples of why you might need to use via in pad:

  • If there is not enough space on the board.
  • It can help with thermal management.
  • Trace routing may be easier with via in pad.
  • High frequency designs benefit from the shortest possible routing to bypass capacitors, which may indicate via in pad.

So if you don't have a choice, here are some methods you can try when using via in pad:

  • Filled viasHave the board fab house plug the via and then plate copper over it. This is our favorite option. It will give you all of the benefits of via in pad without causing problems in assembly. It's really our only recommended via-in-pad method.
  • Use a micro-via that only goes through one layer of the board. Although this may be an okay option, the solder can still wander down into the via, leaving voids.
  • Cap the underside of the board with solder mask. This is our least favorite option because sometimes the cap can pop open, and the void may be big enough to still pull too much of the solder off of the pad.

For more information on via in pad, check out this video. http://scrm.it/viainpad

Internet of Things Got Your Tongue?

By now, most of you have heard about the Internet of Things (IOT). If not, here's a quick summary:

The Internet of Things is the concept of having pretty much everything connected to the Internet in some way shape or form. At the simplest, it's the ability to turn a light bulb off and on with your smart phone. At a more complex point, it is all of the devices in your house, car, recreation, services, and office connected and talking.

Lights will automatically go on and off as you move through your house or office. When it's time to get up for work, your coffee will be brewed, your car will pull up to your door, your house will know when you leave and will lock down and turn off unnecessary devices - all without any intervention from you. The streets will talk. Utilities will talk. Everything will talk, coordinate, and manage.

It won't be enough for your computer to "ding" when an email arrives, or your phone to "buzz" when a text comes in. No; the IOT wants to control your life. And, it wants to nag you about all of it too.

The IOT will be good for us, because it will require a lot of super small parts, which we happen to like. In honor of that, we declared April, 2015 to be Internet of Things month, and created an "Internet of Things gone Bad" poster. The poster, by local graphic designer Kyle DeVore, is 18" x 24" and suitable for framing.

The early birds already have theirs, but we have a few more. If you're a current customer and would like one, shoot an email to ngreen@screamingcircuits.com. We'll give them out until we run out. First come, first served.

Iot_poster_final_OL copy