Showing Off at ESC 2012

Yes, we show off sometimes. We show off and get self congratulatory and self promotional. 'Cause that's what tradeshows are all about. Well, they're about that, but they're also about meeting and listening to people and other good things. In any case, we are proud of what we do (otherwise I wouldn't be doing it) so we go to tradeshows and show off.

In March, we're going to the Embedded Systems Conference in San Jose, California. We'll be in booth number 1437 (map here). Show hours are as follows:

Tuesday, March 27 - 11:30am - 7:00pm
Wednesday, March 28 - 11:30am – 5:30pm
Thursday, March 29 - 10:30am – 3:00pm

Bb-partWe always bring some samples of our work for people to hold on to. We've brought the two Beagleboards that we assembled and a few other pieces of our handiwork. It's cool to pick them up and hold them, but with parts so tiny, it's not easy to really see what you need to see from an assembler - the solder joints. So this year, we're bringing some big monitors and a USB microscope. I've got my eye on this one from Adafruit. As of this writing, it's out of stock, and I'm anxiously waiting for notice that it's back in stock.

Duane Benson
Let's get small


Particle Update

I've been ignoring my Geiger counter for a while now, but I picked it back up and made some progress again. For some reason, I just wasn't getting the 555 based HV power supply to generate a high enough voltage. In frustration, I bypassed the 555 and fed a PWM signal in from a microcontroller board that PIC SMT geigerI have laying around.

That fixed the problem. I still don't know why I wasn't able to the the 555 doing what it was supposed to do. I'll have to spend some more time on that some other day, but for now, I've prototyped it out and I'm happily detecting particles. I whipped out the new layout and will send off to Sunstone.com com for another set of PCBs.

I've also replaced the Atmel chip with a PIC. I don't have anything against Atmel. I'm just more familiar with PICs. Once I've built a few of these, I'll change to really small packages - QFNs or BGAs for the chips - to make the board a little more fitting with our assembly capabilities. The SOIC chips are fine, but our machines don't even come close to breaking a sweat with things that big.

Duane Benson
We treat agoraphobia for PC boards

Who Are You?

A lot of events are preceded with a "meet and greet" session. It gives you something to do for an hour or so before the real activity takes place. I'm not much of a schmoozer myself, but if the crowd is right, there is value in the activity. It's good to get to know folks with similar interests or vocations.

On the Internet, Facebook is kind of known as the place for that sort of thing. The problem with it though is the low signal to noise ratio. Too much drivel to sort through to find the valuable nuggets. But Common ground 0402s schdon't despair. All is not lost. Over at EEWeb, they have something pretty close in their "Featured Engineer" series. As of this writing, they have well North of a hundred profiles. Peruse through and get to know some or the people making things happen in the world these days.

If you look close, you can find yours truly in the list. And the first person to name the science fiction movie I'm thinking about gets a free Screaming Circuits polo shirt. The first person who can correctly identify the lighthouse gets one too. (the lighthouse is small in the photo, but if you've been there, you'll recognise the area) Only in the U.S. though. Sorry, but customs gets me down so I'll only ship to a U.S. address. It might not be the same shirt I'm wearing, but close.

Duane Benson
In life I was your partner, Jacob Marley.

Is your BOM a Smart BOM?

Please be aware that there is no "B" at the end of these BOMs. Still, without the "B", you can have a smart BOM or a dumb BOM. It is important to note, however, that a dumb BOM may not be a bad thing. It just depends on what you want to do with it.

No matter what you're doing, there are a few necessities. Let's start at the very minimum, for someone designing something to be self-built from mostly already owned parts; maybe just a few from a dealer.

Reference designator: R1, R2, R3, C1, C2, U1... You have to have this information.

Quantity is important so know know how many to pull. Although, with a small garage-built project, you can probably just as easily count how many you need for a given value. And what about the value? Actually, the value isn't always all that necessary if you have the correct part number information. A line item number is hand for big bills to keep things straight.

This is actually too basic and kind of pointless, so I'm going to jump ahead. Take an assembly house like Screaming Circuits. Screaming Circuits will either build your boards from your kit of parts or purchase them from your BOM (or a combination thereof).

Once you have the item number, quantity and reference designator, you need to tell your assembler or purchaser what it is. If you already have the parts kit, just add in the manufacturer's part number and a description / value. That should do it. Some assemblers, like Screaming Circuits, will take part numbers from a distributor in place of or in addition to the manufacturer's part number(e.g. Element14, Digikey...)

If the assembly house is going to buy the parts, then add in the manufacturer and double check that the part numbers are accurate with all suffixes and things of that sort. The distributor part number can be added, but when the assembler is going to build the boards, you really should include the manufacturer and manufacturer's part number to cover all basis.

BOM sample

That's cool, but your circumstances might require just a little more. You might need to list an approved substitute or two for parts that come in and out of stock frequently. You could also list multiple distributor part numbers for the same specific component, again, in case of lead-time or stock issues.

Sometimes I get myself into a bit of trouble by not specifying some part values at design time. I might just throw in things like bypass caps, RS232 driver charge pump caps or LED current limiting resistors assuming that I just know what the value is. It's not a big issue, but it would probably be less work to just do it at the start.

Duane Benson
What the Bureau of Meteorology has to do with your parts kit, I'm not sure.

 

Let's Get Small - 0.3mm pitch BGA

I recently got an email from Practical Components about their new 0.3mm pitch evaluation board and dummy 0.3mm pitch BGA. Now, we've been assembling 0.5mm and 0.4mm pitch BGAs for years. Those sizes are kind of not really anything special anymore. We've even been putting together POP (package on package) for a couple of years. But we've yet to see anything smaller.

Shrinking BGA pitchJust looking at the numbers, 0.3 may not look all that much smaller than 0.4, but that's 25% down. Thinking of it in those terms makes it much more intimidating. I haven't found the pad dimensions yet, but just using rough estimates, a 3 mil trace would have about 1.5 mils on either side for a between the pads trace. That's getting pretty dangerous. Likely, you'd have to do every thing with filled and plated-over vias in the pads. (NO OPEN VIAS! Not one. Don't do it.)

I can see a lot of good future use for this size in miniature devices; more processing power in hearing aids and embedded medical devices, for a start. I don't know how necessary 0.3mm pitch will be for phones. They seem to have stabilized in size and the trend is more toward system in chip than it is toward more shrinking. Regardless, I would expect that in a year, we'll be seeing mainstream parts in this form factor.

Duane Benson
Go ask Alice
I think she'll know
How to run your escape routing

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