Adam Wang wrote:
> Phew ~ so we need you ! :-D
> So now you can imagine how we did in previous/traditional company with few
> employees to come out a bom and do a cost down job.

Yeah, hunting for cheap parts is tedious work. Especially if they're
things like resistors or capacitors.

One can actually use the existing boom for this kind of work, but it's
slow and not very convenient:

http://projects.qi-hardware.com/index.php/p/eda-tools/source/tree/master/boom/test/

test.mbq describes what we're looking for. Then you can  make  or
make KITS=N again  to trigger a search for one (default) or N sets
of components. First, you'd  make db  in the parent directory, which
will take a good while. (Note: there may be regressions due to external
changes. I haven't run the database setup recently.)

What's completely missing in the existing boom is a means to estimate
the "commonness" of parts with certain parameter combinations. E.g.,
while technically entirely possible, you'd have a hard time finding
Y5V capacitors with 1 pF, size 1206, and a rated voltage of exactly
6.3 V.

On the fly statistics for exploring the parameter space are something
I definitely want to add in the new boom. Not sure if I'll have this
in a usable state in time for the first round of M1r4, though.

> 3) item 44, 120uF. current it's in dia. 5.00mm, too bigger for routing.

And a bit too tall for mounting under the PCB ;-) Hmm, tricky. There's
a tantalum cap that's only a bit more expensive but a lot smaller:

http://search.digikey.com/us/en/products/F930J157KBA/493-4112-1-ND/2529839

Unfortunately its ESR of 900 mOhm is a bit nasty. This one is 50% more
expensive but has a nicer ESR of 70 mOhm:

http://search.digikey.com/us/en/products/T520B157M006ATE070/399-4732-1-ND/1001103

And for a few extra cents, you get 45 mOhm:

http://search.digikey.com/us/en/products/T520B157M006ATE045/399-4733-1-ND/1001104

- Werner
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