Protypboard-Bestücker?

18/07/2008 - 15:59 von Henning Trispel | Report spam
Hallo allseits,

mich àrgert jedes Mal, das ich bei Test-Boards einen großen Posten für
die Bestückung ausgeben, wovon größtenteils Einmalkosten- /
Einrichtungskosten sind. (Meist mit BGA, oft aber auch nur normal
SMD).

Wenn es mir zu bunt wird, mache ich das auf einem Reparaturplatz
selber. Selbst, wenn ich mein Gehalt für die Bestückungszeit rechne,
ist das noch oft günstiger, als es fremd zu vergeben. Nur: Ich will
das gar nicht selbst machen, dazu ist mir meine Zeit hierfür zu schade
und ich würde wàhrenddessen lieber was sinnvolles machen und kreativ
tàtig sein.

Kennt jemand einen Dienstleister, der auf Prototypenbestückung bzw.
Kleinstserien (bis 5) spezialisiert ist? Am liebsten mit Dampfphase
zum Löten, muss aber nicht immer sein, manchmal reicht auch ein guter
Lötkolben.

Danke für Infos,

Henning
 

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#1 Kai-Martin Knaak
18/07/2008 - 16:45 | Warnen spam
On Fri, 18 Jul 2008 06:59:14 -0700, Henning Trispel wrote:

Kennt jemand einen Dienstleister, der auf Prototypenbestückung bzw.
Kleinstserien (bis 5) spezialisiert ist? Am liebsten mit Dampfphase



SRM in Berlin (http://www.srm-printtechnik.de)
Die haben kein Prioblem mit Einzelstücken und sie benutzen einen Reflow-
Ofen. Bei Serien kleiner als etwa 20 werden die Bauteile nicht mit dem
Roboter in die Lötpaste gesetzt, sondern mit von Menschenhand geführter
Pinzette. Die Einmalkosten dürften bei einzelnen Platinen aber immer
dominieren, insbesondere bei Stückzahl eins ;-)


Selbst, wenn ich mein Gehalt für die Bestückungszeit rechne, ist das
noch oft günstiger, als es fremd zu vergeben.



Es ist nicht nur die eigentliche Bestückunghszeit, die der Bestücker an
Aufwand hat. Nicht ganz unwesentlich ist die Arbeitszeit, die darin
steckt, fehlerfrei zu verstehen, was Du jeweils meinst. Dazu kommt noch
die Beschaffung und Lagerhaltung der Bauteile, die Investition und
Wartung der verwendeten Geràte und am Ende noch der Lebensuntehalt des
Chefs. Just gestern war auf der geda Mailinglist das gleiche Thema dran:

/Bob Paddock
In a past life I worked for a large Contract Manufacture,
http://www.matrc.com . I don't mean this to a plug for them, but the tour
of the place is helpful for the discusion:

http://www.matric.com/tour.html
http://www.matric.com/info/tour/smt.htm

To a CM it is all about *Time*. When it comes to parts, the actually part
cost is really insignificant as far as cost contribution goes. Most of
the cost goes to the time it takes to setup and teardown.

For a broad brush overview of cost steps:

One shot fee for getting your project into the system. Someone has to
enter your BOM, and schedule into the amourphys blob known as "The
System". Any change that you do triggers a recalculation, that you either
payfor or is amortized across your boards. Every future order you place
will have a small "trigger few" to pay for someone to enter your order.

Included in that is a fee for someone to do a time analyze of the number
of operations that your project will require. A unit time value is
assigned to each operation, and each operation has a cost, that is, as far
as I know, calculated by Magick (All CM's use Magick for this step to my
knowledge).

If you supply the parts there will be fees for entering a carrying fee per
new part number into The System. Some cost analysis guru at GM, long ago,
decided to simply have a number in The System carries a charge of $50 or
so per year. The accountants just love to beat up the engineering
department for "we have to many parts in the warehouse". Company owner
wants to keep inventory turnover high. Also cost for physically getting
your parts into The System, such has putting them in the warehouse, typing
in the data etc.

There will be a scrapping fee to get your stuff out of The System if you
take your project someplace else.

Those None Recurring Engineering (NRE) fees you either pay for up front,
or it is amortized across the number of boards. This is why the range can
seem so different between different CMs. Some hide the fees, some don't.

Also when you supply the parts the price of each part will be market up by
a *minimum* of 33% (More Guru calculations). If you don't mark the price
up by this amount you lose money each time you touch the part. You are
changed for the use of the warehouse space, like renting a storage unit.

Now lets say you let the CM supply the parts. In general this will get
you a lower per part cost for the commodity parts. As they will be using
100,000 0.1 uF 0603 caps a day, the pick and place machine will have that
loaded. So you don't have to pay for loading your reel of much smaller
volume part. Also the CM will have negotiated a much better price than
you got from Digikey. The downside here is that you lose some measure of
control, which can be a problem if you have to meet UL/MSHA/FDA etc.
regulations.

Which reminds me there will be extera charges for projects that involve
the pain of FDA paperwork, such a per lot tracking etc. Other acronyms
apply as well, UL, FCC etc.

There is a fee for having the solder paste stencil made.

Now that the NRE's are out of the way, lets build a Thousand Widgets.

Someone answers the phone and enters
an order into The System to build a Thousand Widgets.

The System checks the warehouse to see if all of the parts area available.
Your order is then routed to Purchasing to get the parts that are not
available ordered, or routed to planing to get your order into the build
que.

When your build hits the top of the que:

Someone pulls the parts from the warehouse, at the minimum your PCB; time.

Your bareboards are put in an oven and baked to drive out any moisture,
you pay the handling and electricity; time.

Your parts are loaded on the Pick&Place machine; time.

The board go from the oven to SMT Assembly; time.

Someone pulls your stencil out of the rack and puts it in the paste
machine. Past is applied to your board; time.

Your board is put into the Pick&Place and your parts are mounted; paste,
electricity
and time.

Your board then goes through the IR reflow oven for soldering; electricity
and time.

The boards are then cleaned; fluids and time.

Any of your parts left on the P&P are removed, and put back in the
warehouse, when Widget #1000 comes out the end of the machine; time.

The stencil is cleaned. You pay for whatever the cleaning fluid is and
time.

The stencil is put back in the rack; time.

If your boards are in a array, they are then cut apart. It is cheaper to
build arrays, but it adds this cutting fee; time.

If there are parts that could not be mounted in the P&P machine they are
done by hand, or put through the wave solder machine, then cleaned a
second time. There is a big hit in costs for anyting done by hand such as
connectors, transformers, cable assemblies etc. Time.

The boards then go to Quality Control for the level of inspection that you
paid for. Simple visual to full functional test. Time.

Boards leave QC and go to shipping where they are put in Anti-Static bags
and cardboard boxes and shipped off to you. Time.

You pay the shipping one way or the other.

There could also be Added Value items such as your boards are put in an
enclosure. You pay for someone to do it right down to the number of
seconds it takes to tighten down the screws.

By now you probably have gotten the idea that Time is important. When you
were looking up stuff in the DigiKey catalog were you billing yourself the
time it took to do it? Probably not...

The 500 piece cost for the electonic parts from Digi-key is
about $4.20



Did you include the Anti-Static Bag, the yellow Anti-Static Sticker that
seals the bag, the solder (price of metals is going up every day), and any
board cleaning fluid chemicals / deionized-water in that price of $4.20,
and the time to do those items? I didn't think so...

A good CM knows the cost of every operation and will be around a long
time. A new CM doesn't know his costs. Hence the wide variation in CM
quotes.

Matric developed a reputation for being a high price CM, and customers
would leave based on cost, rather than value. However many of them would
return after a while saying "we got what we paid for", and never left
again.

In the end my advice is to analyze the value of the services you are
paying for, not the cost of the parts.

\


Kai-Martin Knaak tel: +49-511-762-2895
Universitàt Hannover, Inst. für Quantenoptik fax: +49-511-762-2211
Welfengarten 1, 30167 Hannover http://www.iqo.uni-hannover.de
GPG key: http://pgp.mit.edu:11371/pks/lookup?search=Knaak+kmk&op=get

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