I wandered over to the TI booth at the Embedded Systems Conference to check out the Beaglebone and the MSP430 Launchpad. We haven’t built any Beaglebones yet, but a few years back we took the Open source Beagleboard files and built up a couple to show our package-on-package (PoP) workmanship. The Beaglebone doesn’t use PoP, but it is open source. As are the “Capes.” They call their expansion cards capes. I get a vision of Underdog when I hear that name.

What caught my eye was their selection of Capes available now.
All of those are open source. They provide functionality such as displays, battery power, CAN, prototyping and more.

The other product I looked at was the MSP430 Launchpad. I’ve been getting to know the launchpad myself and wanted to see what’s new with it. 0328121213The unit shown here has a DSP and a little display driven by the MSP430. It’s a MP3 player with the purpose of introducing the DSP and MSP430 / DSP combination.

TI is doing an amazing job of making evaluation of its chips easy and inexpensive. I’ve seen a few other companies providing more complete and less expensive than traditional dev boards as well. NXP with their LPC series to name one. It’s a good idea and a good trend as far as I’m concerned.

Duane Benson
Robots good. Neurotic thermonuclear devices bad.


Let’s Get Small – 0.3mm Pitch BGA

I recently got an email from Practical Components about its 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 0.003″ trace would have about 0.0015″ 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


Underness as a Common Theme Again

I didn’t mean to, but here I seem to be with a common theme again. Like yesterday, and again not too long before that — parts under parts seems to be the thing of the hour.

Maybe the caps are shy and are just trying to hide. Or maybe we’ve been writing too much about package-on-package lately. Dunno.

I do wonder though, how many of these issues are caused by parts substitution (the cap originally chosen was narrower), the wrong CAD library footprint, or just a rushed layout. Who wants to vote on that one?

Duane Benson
Just push on it harder. We’ll make it fit.

Pitch Switching

I’ve been reading of 0.3 mm pitch BGAs, but those aren’t totally new. I’m not sure if we’ve done any 0.3 mm pitch before, but we’ve been doing 0.5 mm for years and have done plenty of 0.4 mm pitch as well, even in package-on-package (POP) forms.

Speaking of really fine-pitch BGAs and CSP type things, one topic I found interesting has to do with pitch switching adapters. It’s basically a small PCB platform that has an underside footprint of a 1mm or 1.27 mm pitch BGA and a land pattern on top for a fine pitch BGA. It has solder balls on the bottom, so once sandwiched together, it’s treated just like a big BGA for assembly purposes. [Credit where credit is due: The image below came from the Aries Electric website.]

Such a part can negate the need to re-spin the PCB if your big part is updated and replaced in a new fine-pitch form factor. (Although, personally, I can only imagine that if the chip is rev’ed, there will be some other change that has to be made to go along with it.) The theory is, if you’ve got a really expensive design, this might be a viable option, allowing you to upgrade without a relayout.

Certainly though, at the very least, this could allow you use some newer fancy chips without having to resort to filled microvias and tiny trace and space advanced (expensive) PCBs. Could be quite handy and same some money.

Duane Benson
Platform shoes are back!