ARM, Single-Chip PC, or other architectures for audio stuff?

You can see the boards, judge for yourself. Of course it can be done. Or is a PCI bus running through 3 BGAs and a 64-bit SDRAM bus running into one of them too few signals in your book.

Do you claim to have a bus clocked at 1.6GHz on your board. The GHz range clocks I have seen are contained within the chip, with the exception of a few serial signals which do not take many traces at all.

Dimiter

------------------------------------------------------ Dimiter Popoff, TGI

------------------------------------------------------

I rather much doubt that. There may indeed be more than a hundred micros in a modern car --- but only a very few of those are BGAs. And that's a good thing, too. Cars simply _cannot_ cost as much as hundreds of smartphones.

There are nowhere near hundreds of places in a car that would need so much processing power or external memory that a BGA would be called for. I reckon there's less than a dozen, actually. CPUs like that might appear in the main engine control unit, and in a few places that deal with image processing, but just about everywhere else an (L)QFP between

64 and 144 pins is totally sufficient.

I think you better say if there are any severe latency constraints, and also what you need in terms of software assurance and development processes. And it also sounds like your programmer needs some DSP knowledge.

Maybe you could look up some CS or engineering professors at UC Davis and ask if they can refer you to anyone.

Of course if you have lots of signals, you will need more layers. I was merely saying that having BGA devices does not imply the need for more than 4 layers - it is the signals that need to be routed, not the chips.

For comparison, however, it's worth noting that until recently 4 layers was the norm for PC motherboards with multiple 64-bit memory channels (as well as many other wide buses). Now I believe many of the cards are

6 layer, but that is to handle chips with 2000+ pins and massive power regulators clustered around the processor. The trick to making this all work is careful choice of the pin layout to match the routing between devices - when you are using FPGAs, you can also do such optimisation. (Of course, it's often cheaper overall to add extra layers than to spend the development time getting the perfect FPGA pinout - but it is /possible/.)

Sorry - I failed to read correctly, and thought you wrote that they replaced the BGA.

I would be surprised if they had genuinely confirmed the problem to be BGA failure (meaning soldering problems, detached balls, etc.). That would take an X-Ray and serious analysis, and perhaps also require the removal of components on the other side of the PCB. It's worth doing for a $5K FPGA - but not for a $5 ARM SOC. I suspect "BGA failure" is a tick box meaning "no visible damage, voltage test points OK, but the processor or memory is not working properly".

As for the environmental issues, it's still better that the whole PCB is replaced than the usual alternative - replacing the whole phone.

Of course, old "mechanical" cars can fail too - the Toyota is at the workshop today to get the exhaust re-attached. But it has the great advantage that /every/ workshop can fix it - no need for specialists.

I too prefer cars to be a bit more "mechanical". But we are in the minority, and are unlikely to change the direction of the motoring world. All we can do is hope that we can patch our old cars until we replace them with Zimmers :-)

If that size is fine for you, then I agree that BGA is not necessary - but I still cannot imagine that a small BGA would be the likely failure point as your board gets abused. My money would be on the connectors, the screen (if it has one), internal cables, or heavy components such as inductors.

Still, it is /your/ board - it is /your/ experience that your customers pay for, and you have to pick parts that you are comfortable with.

Since that's a major corporation I think they have their procedures. BGA failures usually manifest themselves in felx sensitivity. For example, you flex the board a little in a certain way and it works again, unflex and it quits.

True. But if BGA avoidance reduces the number of cases that's even better.

[...]

Plus the repair bills are in the low three digits versus serious four-digits. A lot of times you can do it yourself.

When I needed an SUV I looked which one had the least in electronics, faired well at the brutal Rallye Paris-Dakar and was popular in less developed coutries, then bought it.

[...]

No screen, no internal cables, no heavy parts (unless heavily supported and mechanically compliant), external cables fixed and strain-relieved.

Yup :-)

--
Regards, Joerg 

http://www.analogconsultants.com/

Latency is not critical as long as it's always the same or data streams remain at least lined up to each other. On a Samsung NC10 with Windows XP it works beautifully so it can't be rocket science.

It's medical so a good design history file and hazard analysis are crucial. But I can coach. Main thing is that the contract engineer has good documentation habits and understands that comment lines in source code do not constitute sufficient documentation the eyes of an FDA inspector.

Yesterday afternoon I found someone who should be able to do it. Very much local, about 15 minutes by car. I wish there was a safe route to get across by bicycle but the road is dangerous. I love riding mountain bikes but the alternative terrain in that direction is super brutal. Although now that I have a new bike with suspension I might try that again (last time I broke the rear axle of my old mountain bike).

With the previous SW designer it would have been even closer and easier by bike but he moved out of California.

--
Regards, Joerg 

http://www.analogconsultants.com/