FCDEV3B status update

Mychaela Falconia falcon at ivan.Harhan.ORG
Fri May 6 01:57:16 CET 2016

Hello FC community,

I've got some updates on the quest to produce our own FCDEV3B Calypso
modem boards:

1. I am still waiting for a definitive answer from my anonymous
   off-list contacts as to whether or not they are going to cover the
   PCB fabrication for us, and if they are, what timeframe should we
   expect.  They emailed me last Friday suggesting that they are going
   to be covering the PCB fabrication whereas I will need to take care
   of the assembly both for ourselves and for them, but the way it was
   worded makes it seem like a tentative proposal, and I am still
   waiting to hear something more definitive.

2. The good news is that if we have to cover the PCB fabrication on
   our own, I found another fab that can do it for much much cheaper
   than the first one I got quotes from.  The previous price figures I
   was going by, where it would cost about $6200 USD to make 10 boards
   and going up from there, were from Sierra Circuits aka ProtoExpress
   - they are a PCB fab in California, USA and I started with them
   because I had good experiences with them in the past on much
   simpler boards - I used them back in 2009 to make PCBs for my SDSL
   modem design.  But as soon as I did a little shopping around, I
   discovered that their prices are crazy high.  I don't know if it's
   just Sierra or all "first world" PCB fabs, but I know now that
   Chinese fabs are a lot cheaper, and contrary to what I heard before,
   at least some of them are perfectly willing to do small quantities.

The nice fab I found is www.pcbcart.com, and what is really neat is
that their fully automated online instant quote calculator form can
handle complex boards like ours.  With most fabs the automated instant
online quote calculators can only handle simple boards, whereas
complex ones like ours require manual quoting, i.e., one has to send
the design files to the fab company for manual review and get their
human to generate a custom quote.  At first I assumed that pcbcart was
the same way, so I sent them a link to our gerbers and asked for a
custom quote.  A couple of hours later their sales rep replied to my
inquiry with a PNG attachment - it was a screenshot of their online
quoting form with all specs entered correctly, fully capturing all
price-affecting properties of our board!  I was then able to go to
their site myself, enter the same parameters, and then play around
with different order quantities and other settings, and immediately
see the price quote for each option without having to bother a human -
so neat!

By playing around with their form, I determined that the best deal we
can get from pcbcart is to order 25 boards for $2274.83 USD - contrast
with the $6200 or so that Sierra wanted!  25 boards would be the
optimal order quantity for the first fully-at-risk batch - given the
online form which allows one to see the price for any quantity without
bothering a human, I checked out of pure curiosity how much it would
cost to order just one board - it said about $1500.  Ordering 5 or 25
pieces would cost about the same because of the way the per-unit price
goes down with quantity, thus 25 pieces definitely seems like the
right sweet spot.

All in all, if we have to produce the first batch of our FCDEV3B
boards (I call it the at-risk batch because the costs would have to be
spent before we can know for sure that our design is good, that our
aftermarket-sourced Calypso chips and other such parts are good, and
so forth) on our own without any outside sponsor covering any part of
it, we would need about $4200 in total to make this at-risk first
production batch: order 25 PCBs and then populate between 5 and 20 of
them depending on the level of demand for finished boards.  This total
cost breaks down as follows:

* about $2300 for the PCBs from pcbcart, after adding shipping;
* about $450 to order the remaining "special" parts (the ones that are
  no longer made new and can only be obtained as surplus on the Chinese
  grey market, just like Calypso &co) from my trusted supplier;
* about $600 to order 20 sets of those parts which are readily orderable
  from Digi-Key/Mouser/etc - it's about $30 per board, so adjust
  accordingly for different build quantities;
* another $600 to reball the Spansion flash+pSRAM BGA chips from RoHS
  to SnPb using a BGA reballing service - yes, I plan on building our
  boards with real SnPb solder, none of that lead-free crap - but for
  this one critical BGA chip only RoHS parts could be found, hence
  they would need to be reballed;
* $220 for the Kamaya RAC101A3C parts - these ones *can* still be
  bought new, without the uncertainties inherent in sourcing parts
  from the grey surplus market, but we would have to order a full reel,
  hence the non-trivial price.

Thus if we have to crowdfund the production of our first at-risk batch,
instead of the figures I put out last week (need 15 board preorders at
$650 each) we can go with lower figures: let's say we need to gather
10 board preorders at $450 each.  Is there enough interest in these
boards amongst our community to where we could gather 10 preorders with
prepayments of $450 USD each?

I shall keep you all updated if I hear anything more from my anonymous
off-list contacts.

Hasta la Victoria, Siempre,

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