Friday the 13th. Should You Worry? No.

So, here in Oregon, USA, it's Friday the 13th - and, we have a full moon, to boot. In many societies, both of those would portend of doom. Baseball players tend to be a suspicious lot, so if you're a baseball player, you should stop reading now. Everyone else, keep going and I'll explain why there's nothing to worry about.

Well, the first reason that there's nothing to worry about, is that superstitions are really a bunch of hooey.

DFB full moonBeyond that, it's important to note that we speak hexadecimal here. That means it's really not Friday the 13th. It's actually Friday, the 0x0D. It won't be the true 13th until next Thursday, and there's no superstitions that I know of about Thursday, the 13th.

As far as the full moon goes... There does seem to be a certain amount of anecdotal evidence suggesting that there's more looniness when the moon is full. However, looniness isn't necessarily a bad thing. If you're an officer of the law and your job is to protect the world from 2:00 am two-beer-heroes, then most certainly, extra care must be taken.

On the other hand, in fields requiring creativity, a little looniness can actually help the cause. Tesla clearly had his looniness, and look what he did: pretty much invent the modern world. Einstein? Yeah; a good kind of loony too.

So there you go. Revel in the potential for extra creativity. Don't worry about Friday, the 13th, because it's not the 13th. And, don't worry about the full moon either, because, why worry?

Duane Benson
I'm certainly happy I live in a split-level head

Panel Rails - What Are They?

I referred to "panel rails" in my blog about V-score panels, but I didn't explain the "whats" and whys" of panel rails. You might find yourself asking "what are panel rails and why would I want to use them?"

Well, first of all, for our Full-Proto service, we don't require panels or panel rails. We'll take just about any old board that's bigger than 0.75" x 0.75" and smaller than 14.5" x 19.5" and run it through our machines. For our short-run production service, we only require panelization for boards less than 16" sq.

That being said, panel rails do have a purpose. They give the machines a spot to grab onto without coming close to components. They're also a convenient place to put fiducials (more fiducial info here).

As you can see in the image below, the panels give a clear area for handling the panel.

Tab routed panel

There are two important things to note about this panel. First, look closely at the four outside corners. You can see the scoring for easy separation of the rails. This designer made sure that there isn't any copper where the scores are. That's the right way to do it. The V-Score blog shows a panel rail done the wrong way - with copper across the cut.

Next, this board has fiducials. Good. But, the fiducials are in a symmetrical pattern. Not so good. IPC-7351b-3-10 specifies a non-symmetrical pattern so that the board can only be processed in one orientation.

Duane Benson
Once I build a panel rail, now it's done
Brother can you spare a diode

The Past and Future of Electronics

Our parent company, Milwaukee Electronics was founded 60 years ago, in 1954. That's quite a long time in terms of electronics.

  • 60 years back

1954 was a big year for transistor electronics. The first commercially produced transistor radio, the Regency TR-1, was put on sale in November 1954, for a price of $49.95. The Bell Labs TRADIC, the first transistorized computer in the U.S. showed up in 1954.

TiconIt was also a big year for nuclear energy. The first civilian nuclear power plant went on line in Russia (whether it was a military research facility or a power generation facility is under debate). The European CERN nuclear research organization was formed.

The first atomic powered submarine, The Nautilus, was commissioned by the U.S. Navy. 1954 also saw the U.S. explode the first hydrogen bomb. The Atomic Energy Act of 1954 paved the way for the civilian use of atomic power in the U.S.

The magazine Popular Electronics debuted in October 1954. That issue covered, amongst other things, a solar "battery" with 6% efficiency, radio control of models, and capacitors.

That was a bit of the past. What will the future of electronics hold? What will technology look like in 2074? Will the world even be recognisable at all?

  • 60 years forward

Well, hopefully, there won't be any new developments in the area of bigger and more powerful bombs, like in 1954. Hopefully, we won't have been enslaved by our new robot overlords. Regardless, electronics will be vastly different in 2074.

The concept of a printed circuits board will have long passed by that year. Electronics will be more of a construction material supplement.

Processing power and sensors will come in a bag, in the form of tiny particles. They'll self-power with energy harvesting. They'll have integrated wireless communications. Each one, won't do much, but when added together, they will essentially form a big piece of programmable logic.

Take aircraft paint as an example. The paint manufacturers will mix in intelligent "dust." The aircraft paint will get a ratio or 40% computational dust, 10% strain gauge dust, 20% rf/temperature/light/moisture sensor dust, 20% actuator dust, and 10% other miscellaneous functionality dust.

Once applied to the aircraft, the paint will manifest itself as a giant programmable logic and sensor array. The paint will cover communications, location and all forms of sensing and maneuvering.

The smart dust will be mixed up in different proportions, based on the application requirements, and added to everything. Even food.

Duane Benson
I think that pill will be ready long before the year 3535

Individual routed boards - not panelized

Some people, especially in the manufacturing industry, refer to PC board panels by the term "palette." I can't seem to avoid thinking of the big wooden thing used for shipping stuff, so it's tough for me to call a panel a palette. It is, however, a correct designation - as is "panel.".

Milled cornerThis post is about individual routed boards, as in not in panels. Last time, it was tab routed, and before that, V-score.

On the right, you can see the relatively smooth edges of an individually routed board.

If panelization is so cool, you might ask "why not always panelize?" For large quantities, or really, really tiny boards, you really should ask that question because it's pretty much always a good idea. There are, however, good reasons not to panelize when in the prototype world.

First, with small quantities, you may not need enough boards to fill up a full panel. You can save quite a bit of money when ordering five individual boards, than if you had to order a panel of 30.

Fab houses tend to gang up board designs from a lot of different customers onto one panel. That allows for less waste and faster Milled edge 2turns for small quantity boards. The end result of that is that many fab companies charge more for panelization when quantity is small.

Our Full-Proto service can take individually routed PC boards down to 0.75" x 0.75". Our higher volume, more economical service, Short-Run requires that PC boards smaller than 16 square inches be panelized.

Duane Benson
Well my buddy Jim Bass he's a-workin' pumpin gas
And he makes two fifty for an hour
That's not very much

Tab Routing panelization

In my prior post, I covered V-sore panelization. The other very common panelization method is called tab-routing, as in routed, but with tabs. (That's "routed" like using a router, not as in Napoleon being chased out of Russia.) Following this paragraph, we have a tab-routed panel. I've obscured the detail of the PCB to protect the innocent.

Tab routed multi panel 1024

You can get it without the perforations, but if you're separating them yourself, you'll most likely be glad to have the perfs there. If we deem that snapping will cause undue stress on the board, we use a special tool to avoid putting that stress on the boards. If 1-Image30you're separating them manually, the perferations can make a big difference. Next, on the right, is a close up of a actual tab. The three holes make it "Tab Routed with Perforations."

A big advantage to tab routing is the ability to make boards in shapes other than rectangles. On the down side, it takes a bit more PCB material and can put a lot of stress on the area near the tab. That being the case, we recommend that you not put components too close to the tabs.

Now, the definition of "too close" is an interesting one. The IPC doesn't seem to have a specific standard covering the subject. 100 mils, or therabout's, is a reasonable target. Larger or stiffer parts might require a little more space.

When you purchase your PCBs in panels, you can separate them before assembly or after. Generally, the reason for panelization is for ease of assembly, so post assembly is the most common approach. Post assembly separation also requires the most care.

As I said, we have a special tool to avoid stressing the boards when nesessary. If you're separating them and don't have a tool, resist the temptation to just snap them apart like a Saltine cracker. Take some time and do your best to avoid much bending.

If snapped carelessly, or if parts are too close to the tabs, parts can break off. Sometimes the solder joint will just crack, leading to intermittent problems or later field failures. Use of some sort of cutting instrument that won't bend the boards is the preferred method.

Duane Benson
Have no fear; Underdog is here!

V-Score panelization

V-score top viewMy last post talked a bit about panelization, in general. Today, I'm taking a look at V-Score panelization. V-score is created by running a V-shaped blade across the top and bottom of the panel without cutting all the way through. The board in the mini-image of my prior post is V-scored. Top left, on this page, is a close up of the V-scoring. [Note that the cross-hatched area is not in the active circuit portion of the panel. It's in the rails. You'd never want to cut through copper like that in part of the board that will be used. Even here, it would be best not to have copper in the path of the v-scoring blade.]

You'll note that it's all straight lines. V-score can only separate rectangular panelized boards. For curves, you'll need to use a different technique.

V-score edge onThe next image down, on the left, shows an edge-on view of the V-score. You can clearly see what I mean by "without cutting all the way through." The cut leaves enough material to hold the boards solidly together during processing, but easy to separate.

V-score de paneled edgeBy the way, we generally don't just snap them apart. We've got a special tool - a bit like a pizza cutter in a fixture - specifically designed to separate them without stressing or bending the board. If we feel there's any risk of over-stressing, we'll use the tool.

The next image, here on the right, shows a board edge after de-panelization. Note that it's not a smooth, flat edge.

In contrast, the next image down, on the right, shows a flat milled edge. Generally, though, you can't visually tell the difference without close examination. You can, however, feel it if you run your finger lightly along the edge. Just be careful to not get slivers.

Next time, I'll examine tab-routing, which will allow for non-rectangular shapes.

Milled edgeDuane Benson
"I saw two Buffalos, two Buffalos,
Buffaloes on my lawn,
Romping all around and stomping on the ground
And all of my grass was gone."

PCB Panel Routing Technique

Most PCBs we receive are individually routed, i.e., not panelized. That doesn't mean that, sometimes, sending them in a panel isn't a good idea, or required. Generally, we don't require panels (sometimes called a pallet), but there are some cases when we do.

V-score panelIf the individual PC board, destined for Full Proto service, is smaller than 0.75" x 0.75", it needs to be panelized. If a PC board needing Short Run production service is less than 16 square inches, it needs to be in a panel of at least 16 square inches to qualify for Short Run.

So... you ask... why else might I want to panelize my PC boards? Keep reading and I'll tell you why.

  • First, if you've got a lot of small boards, it's easier to handle and protect then when they're in a panel. A few panels can be more safely packed coming and going from our shop here.
  • You may be able to get the through our factory faster. If you have a really large number, and need them super fast, panelizing them may enable that fast turn. With a lot of boards, sometimes, it simply isn't physically possible to put them all on the machine, run them and take them off, in a short turn time. Panelize them and the machine will be running longer for each board change, which reduces the total run time.
  • It may also cost you less. If you use leadless parts like BGAs, QFNs or LGAs, you can usually reduce your cost a bit by panelizing the boards. Leadless parts cost a little extra because of the X-Ray test needed, but the extra handling is mostly per board, rather than per part. One panel of ten boards with ten BGA, in total, will cost a little less than ten individual boards with one BGA each.

Stay tuned for my next few posts where I'll cover the pluses and minuses of different panelization techniques.

Duane Benson
"I looked outside my window and what do you think I saw?
The strangest sight I've ever seen you'll never guess just what I mean,
I can't believe it myself"

Component Packages - Let's Get Small

I've been on a bit of a package binge lately. First talking about metric vs. US passive sizes, and then a very tiny ARM Cortex M0 from Freescale.

The Freescale BGA part checks in at 1.6mm x 2mm. That's cool and I'm almost always in favor of making things as small as possible, but, as I wrote in my prior blog on the subject, it's not always possible. The 0.4mm pitch BGA is problematic unless you can spend a lot of money on the raw PC boards, or will have super high volume.

Small boardAll is not lost, though. You still can use a tiny ARM Cortex M0 part. Just not quite as tiny. That same part also comes in a 3mm x 3mm QFN package. You lose four pins (16 vs. 20) going from the BGA to the QGN, but if you can handle that, it's a very viable option that doesn't require any exotic PC board technologies.

A few years ago, QFN's were scary, but not so much any more. I've designed a few of them in using Eagle CAD. Just be sure to pay attention to the footprint. A 6 mil trace is more than small enough for a 0.5mm pitch QFN.

Duane Benson
Strive at all times to bend, fold, spindle and mutilate

Beginning FPGAs

An hour later, you can join me to explore the very basics of Field Programmable Gate Arrays in FPGAs - Light at the End of the Learning Curve.

The session is on Tuesday, April 1st, from 3:30 - 4:30, in SJCC 210C

FPGA talk EELive 2014

Best Practices in PCB design

If you do happen to end up at the EE Live show, be sure to catch my session: Best Practices in Circuit Board Design. I'll show the most common traps we see that can cause manufacturability issues.

The session is on Tuesday, April 1st, from 2:15 - 3:15, in SJCC 210D.

Best practices talk EELive 2014