[Arm-netbook] Crowsupply update

[Neil Jansen]

On Mon, Jan 8, 2018 at 4:32 AM, Hrvoje Lasic <lasich at gmail.com> wrote:

> did you ever think about in investing in small PNP machine (or just small
> oven plus some hand tools), like being able to produce small batch in house
> and test it qucikly?
>

No, this would be a horrible idea, I speak from experience here.  If the
end-product had a few parts (Arduino-ish, BOM < 30 parts), if the smallest
passives were 0603's and if the smallest IC's were SSOP's, then yea it
MIGHT be doable.  But the EOMA68 board has BGA's and (I'm guessing) 0402's
and likely some 0201's?  The yield rate in a DIY situation would be
prohibitive.  It is actually cheaper to pay the labor rates and NRE's to a
professional that has a process that's dialed in, and a line of machines
that aren't toys.



> do you have any idea how reliable www.openpnp.org project is currently,
> for
> example to meet your specs on board with soem available hardware?
>

I know the author of that program personally, I hired him and paid him to
work on that program for a few months as we tried to make a small desktop
machine that could do solder paste application and reflow in addition to
pick and place.

OpenPnP works, but that's not the issue.  Stencil printing issues and
reflow issues would still make the yield horrible.  Cheap manual stencil
printers lead to issues like tombstoning.  Cheap reflows don't get the heat
even, which means that certain parts of the board don't get fully
soldered.  There's a reason that the professional machines are several
meters long with various temperature zones and there's a reason that they
take a bit of effort to setup correctly.  Even if he got some surplus
machinery and an area to set it up (including ducting for the exhaust and
three-phase AC hookup), there's still the issue of nailing down the actual
process, there's just so much to go wrong and that's why so many companies
leave that sort of stuff to other companies that are better situated to
deal with those kind of problems.

It's not exactly easy for me to say this either, because my dream was to
make a machine for projects like EOMA68; to make the development cycle
cheaper and quicker.  I failed in that regard, and honestly nobody out
there has really nailed it to the point where you could start churning out
single board computers with BGA's an tiny parts and get close to 100%
yields, in a DIY setup.  It's sad but that's the reality that we live in.


For the record, while I vehemently disagree with LKCL on other matters like
3D printing and funding via bitcoin mining, I do completely agree with his
decision to get a few boards produced and tested before doing a complete
run.  Even with all the review, there are still plenty of possibilities for
show-stoppers.

The only suggestion that I would make -- and it's a big one -- is to send
Mike (at the factory) a full test rig that is capable of verifying that an
EOMA68 card works properly.  This is an essential step of every production
run, and I'm honestly surprised that in the update LKCL is planning on
doing that himself. which pushes the schedule out to the right by another 3
days.  This test rig would merely be a little board that the card plugs
into, with HDMI monitor, keyboard, and some testing software to test the
memory (Memtest86+), hard drive, peripherals, etc.  Once production is
going, the factory will need to be testing them anyway before they leave,
this would be a good opportunity to test them, yet I saw nothing about that
in any of the updates or email traffic.  Even if this is something that
LKCL personally does not have time to work on, surely someone in the forum
could take on this task.  So how were you planning on approaching the
factory testing?  If you've got it all figured out, then why isn't it going
to be used for the next immediate run?  And if you've not had time to get
to it at all yet, why not let someone on the mailing list work on it?  I
can certainly give a lot of advice in this department.  Hardware and
software testing of embedded modules is not only what I do at my day job, I
had a lot of experience while living in Shenzhen in how to make test
fixtures for embedded products.  I've got advice on how to make them
bilingual so that they can actually be used in the factory by non-English
speaking test technicians, and lots of other advice.  Just let me know.