Re: [Autopilot] PCB Board Quote

[<hu...@sw...>]

On Tue, 16 Apr 2002, Brett Burnett wrote:
> We can have a 2 layer board fabricated for $33 each.

What dimensions are the board?  For the rev 1 boards, I used
ExpressPCB.  They charged $60 for three two-layer boards with
unlimited holes and traces.  No solder mask or silk screen at
that price and only one size available.

> [...]  We would also have noise problems in the power distribution
> from the digital logic switching.  This could effect the reliability
> and accuracy of the sensors.  

We could have their power supply regulated independently of the CPU's
power.  Since this board is going to be two-layer in the end, we could
go ahead and finalize its layout now.

> The other negative is that the board wouldn't be a true prototype since
> the power distribution wiring would be dramatically different than the 4
> layer target.  This difference means that the entire board would probably
> be routed differently.

Only the CPU board -- the sensors would be on their own two layer board
in both designs, right?  So if we have that board designed, laid out
and tested, we can reuse it once the CPU boards are put together.

> Just for kicks I also quoted a 4 layer board, measuing 4"x3".
> Surprisingly, the quote in quantity isn't much more expensive.

That's what I found, too.  Once the quantity exceeds ten or so
units, the prices drop dramatically.  I would hesitate to order
too many of the prototype CPU boards, since they are likely to be
only temporary while we test the CPU.

The sensor boards, however, would likely benefit from a larger
run.  Since we will reuse them on the

> Is anyone else in the group interested in trying to hand assemble a 
> prototype?

I'm interested, but I don't think anyone should let me near a soldering
iron...  I've found some one in Frederick, MD nearby that does small
jobs by hand for reasonable rates.  He isn't looking for large scale
production runs, so the < 10 boards are doable.

> I'm going to publish a new BOM today or tomorrow.  The
> overall component cost is going to come in around $100 to $120,
> assuming no free samples.  The component cost and board would make
> a completed prototype cost around $130 to $170 each.

Just to be clear, does that also include the inertial sensors?
By my calculations, the three ENC-03 and two ADXL202-EB are a large
fraction of that price.

Aaron pointed out that we might want to include drill holes for
a variety of gyros -- the Tokin units operate with similar
characteristics to the Murata ones, but require a slightly different
foot print.  It shouldn't be too hard to accomodate either gyro.

Trammell
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