I’ve done quite a bit of this. My assembler of choice is Small Batch Assembly.

It all sort of depends on what you call “reasonable.” PNP assembly is a bit like PCB fab in that there are rather large set-up costs and the per-unit cost after that is quite low, which favors volume.

Any way you slice it, I’d expect that 10 boards is too small a number for it to be economical. I’ve done 10-20 panels of boards at a time with SBA, and that’s worked out ok, but that’s amortizing the cost over a couple hundred units at a time.

SBA has a free quote widget on their site that will give you a ballpark number given your BOM size, board and panel count. I particularly like that there’s no hook from that widget to a greasy salesman trying to glad-hand you. :)

On 6/23/16 12:28 PM, Bob Stewart wrote:

I've used Screaming Circuits in Oregon as an assembly house. They've
done ok for us, but I have no idea if they are inexpensive in your context.

The biggest boards I've done with them have been 4x6", but they have SMA
and MMCX connectors, maybe 100 components, mostly SMT, but a few DIP
carriers.

Hi

Around here, assuming:

1. You supply all the parts on full reels with leaders
2. There is no hand assembly work
3. You already have framed stencils that are the correct size for their gear
4. You have multiple proper solder and placement fiducials  on both sides
5. The boards are designed to mount on their gear
6. Your parts and design rules fit their gear and rules.
7. No electrical test, visual inspect only.
8. Best effort only, If the part does not solder etc, you replace it on your time.

You can get various places to look at a batch for $500 to $1000. If your stencils !=
their stencils figure $100 to $200 each.

If you want to ship things a ways, you can save a bit of money. Shipping plus packing
always seems to be a bit expensive.

By far the best approach is to get all of their rules before you start a board layout. Then
do it in whatever arrays / panel size they are set up for and all the other little details.

This all starts to make a lot more sense to the local outfits when you are talking a few hundred boards.
Even more so if it is a few hundred boards a month, every month for a few years.

====

Some math:

120 parts on 10 boards is 1200 parts. A good machine will do that in < 6 minutes. Setting up the machine,
loading and unloading the machine, pulling boards on and off the machine, programming the whole thing,
validating everything ….. that’s an afternoon’s worth of work (maybe more) and maybe an hour of down time
on the machine.

====

Of course for a few thousand dollars you can buy your own pick and place machine ….

Bob

On 6/23/16 2:56 PM, jimlux wrote:

I went and looked up some typical quotes from Screaming Circuits.. we're
typically doing a 4-20 boards, and to place <100 parts runs us about
$20-50 per board (if I had to guess about their "setup vs each" pricing
based on the different volumes I had quoted for the same board, I'd say
setup is in the $250-300 range, and assy is in the $15-20/board range.

Not everything on these boards is machine placeable, and there's some
hand assembly required (like soldering pins into a carrier, and then
soldering the carrier onto the board).  There's also some shielding cans
that may or may not be machine placed and soldered.

On Thu, Jun 23, 2016 at 1:09 PM, Nick Sayer via time-nuts
time-nuts@febo.com wrote:

Tempo Automation in San Francisco is trying to fill this gap in the
market for prototype quantities of boards.  I used them a couple of
years ago and they did a good job for a good price.  Looking at their
website now (http://www.tempoautomation.com/) it appears they've
expanded into fabbing the board for you as well as assembling it.

Henry

Disclaimer:  I've not used any of these yet.  New style assembly houses
are MUCH cheaper than traditional proto shops.  The ones I'm planning on
trying are:

Macrofab (Houston)  https://macrofab.com/

pcb:ng http://pcb.ng/index.html (currently in beta with deep
discounts.  $1/sq in + BoM cost

Small Batch Assembly  http://www.smallbatchassembly.com/

All of these guys have their advocates. All will do under 10 pcs.    I
plan on running a similar job through each of them and seeing what I find.

On 6/23/2016 2:28 PM, Bob Stewart wrote:

--
mailto:oz@ozindfw.net
Oz
POB 93167
Southlake, TX 76092 (Near DFW Airport)

On Thu, 23 Jun 2016 19:28:15 +0000 (UTC)
Bob Stewart bob@evoria.net wrote:

Unlike what most people seem to think, small batches of PCBs have always
been a business for some assembly companies. I know a couple of those
in Europe that are specialized in small volumes (<100pcs per batch) and
reject anything larger. If you google for "PCB prototype assembly" you should
find some in your area. The more electronic industry you have in your area,
the more you will find those assembly fabs. Especially if your electronic
industry consists of mostly small, specialized companies. There are also
some inter-regional companies specialized on hobbyist market, like macrofab.

The prices vary a bit, depending on where you live, but usually
using 2*(BOM cost) and/or (BOM Cost)+300 are good estimates for
how much it will cost to build a PCB. "Going east" might also be
a good strategy. I know one fab in Estonia (Alktech www.alktech.com)
that does offer pretty competitive prices, while giving better quality
than what you usually get from china. The advantage of "professional"
companies like Alktech over "hobbyist" companies like macrofab is,
that you get full professional support while the price does not differ much.
E.g. while macrofab only does 4 layer boards if you specially ask for it,
for Alktech getting any number of layers is standard procedure.

If you want to keep prices low, then the first thing you should do is
to minimize your BOM: The fewer different parts you need, the better.
Ie if you have 200R, 100R and 50R resistors in your design, replace the
200R and the 50R by series and parallel connected 100R resistor. The cost
of a single resistor (transistor, chip, ...) is usually much lower than
having to handle another reel/tray. Especially if the fab has to go onto
the bigger pick&place machine because the number of feeders needed didn't
fit on the small machine.

The second cost saving thing is to minimize through hole components. Use
SMD as much as you can. It doesn't cost much to place an SMD component.
After the pick and place (which can be manual work on small volumes) the
soldering is done in an oven. But soldering a THD part means that someone
has to solder it by hand, as it would be too expensive to perpare a machine
for this. You can take this even further to let the fab only populate the
SMD parts and populate the THD parts yourself, which then only costs a bit
of time. (In my experience, THD solder jobs vary quite a lot more in quality
than one would expect. So doing it yourself might even improve quality).

The last way to minimize cost is to use common components and give the
fab the freedom to choose replacement parts. This gives the fab the
opportunity to choose parts that they already have on stock or buy
in large volumes, which makes them a lot cheaper. But means that you
specify the parts such that they are only as restrictive as you need.
I.e. if most of your reistors can be 5%, then specify them as 5% and
not as 1%. Even odd percent numbers are ok, though usually frowned upon,
as the company will choose the next better rating they have on stock.

Oh: and one additional hint: do not get the PCBs yourself. Let the fab
buy them. Then they will be panelized in the way they like it the best.
There is of course a little price hit if they buy it, but it usually pays
off when taking NRE costs into account.

As for doing assembly yourself: Yes it's possible and a good way to save
money. But be prepared to experiment a lot until you get consistent
and good results. Unless you have some serious experience in machine
soldering you will need a couple of runs in the beginning to figure
out how to do it right. And some things only show after a couple of
months/years after soldering (like borderline cold solders, cracks,
whiskers, popcorn packages etc) that depend on the quality of solder
and settings of the solder process. Also, IR solder ovens do not work
well with anything that casts a shadow on the solder joint, like QFN
or BGA parts.. or even high parts (alu capacitors or connectors)
next to low parts (IC's, resistors). That's the main reason why industry
pretty much stopped using (pure) IR ovens for production and switched
to convection type and vapor phase ovens.

An alterantive to the ubiquitous IR ovens are rework-heater plates.
These are basically just electrical stoves with temperature control
and a PCB holder ontop. They are ment as helpers for reworking, when
large ground planes confound any attempt of using a soldering iron.
By heating up the PCB to 50-100°C it is easy to get the last few
degrees with an iron. These heating plates can go up quite high in
temperature and thus allow the whole board to be soldered/unsoldered
at the same time. For obvious reasons this works only with single sided
PCB designs, but usually gives a better and more even result than
with an IR oven, especially for QFN and BGA.

		Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

On 6/24/2016 8:23 AM, Attila Kinali wrote:

Lotsa stuff deleted

Just to correct a misunderstanding. Macrofab, Small Batch Assembly, and
PCB:NG are all professionals, not hobbyist companies. they focus on
small runs at low cost, but they are manufacturing professionals with
commensurate results.

--
mailto:oz@ozindfw.net
Oz
POB 93167
Southlake, TX 76092 (Near DFW Airport)

On 24 June 2016 at 14:23, Attila Kinali attila@kinali.ch wrote:

For my sins, I am one of those... (Cambridge, UK).
Yes - semi-manual assembly is the way it goes, especially for the
active parts. It's just not worth teaching the machines and loading
the parts for small runs. Typically, passives with more than 20
instances I'll load onto the machines, then do the rest by hand on a
manual placer.

Stencils - not any more. I use a dispensing robot, which is fine down
to 0.4mm pin pitch as long as the ambient temperature is right (35oC,
quite deeply unpleasant to share a room with). No more cleaning
stencils, throwing away paste, or wishing that the customer-supplied
stencil wasn't unhelpful in one of a thousand ways. It also means that
I can go from CAD data to built boards in less than a day, if I ply my
local PCB house with enough cash...

I definitely concur with the 'make it SMT as much as possible' plan -
pin-mount stuff is a pain. Also, QFN is far preferable to QFP, as
catalogue suppliers don't always manage to ship fine-pitch stuff
without bending legs in one direction or another. Reworking a duff QFP
(or fine-pitch SOP) can take as long as assembling a whole board. With
small volumes, there's no real statistical process control, you just
do what you think will work, fix any defects, and update the big
logbook of results.
Hacked reflow ovens have a place, but there are some parts that simply
won't solder with IR - the heat load to get the balls to melt is more
than it takes to kill the part. LTC's modules are especially bad, but
any BGA runs a risk. I'm a recent and thorough convert to vapour phase
(which can also be done in a homebrew manner).

Also - Pleeeeease overbuy components!
those extra few 0402 resistors cost you a penny. Finding the one that
pinged off or the machine threw on the spitback pile - impossible.

Sorry about the offtopic. (I'm also a moderate frequency nut and EMC
chamber owner, so am starting to get nutty about RF amplitudes, which
is a whole new game...)

Steve