Power Engineers + PCB layout
Yzordderex
suffer from extream anxiety when I have to deal with some pcb
designers.
regards,
Bob
EEng
wrote:
I don't know who you're talking to, but I do my own schematics, PCB
Layouts, and Firmware myself. I understand the problems related to
working with multiple engineers and no longer have that anxiety since
my own experience has taught me what critical information other
engineers would need.
EEng
Geo
My Power Engineer gets called in for consultation at a very early stage of the
design (to decide which components he can dispense with in order to fit the
pcb). We discuss where the main current paths are (usually obvious - but often
secondaries need specifying) and he goes away and twiddles his thumbs while I do
the work. We occasionally converse by telephone/email during this period (do you
really want this short across the caps?) Later he visits to see the nearly
finished design and niggles for an hour or so. I do the final mitreing, copper
fills, text (works of shakespeare on a postage stamp) and send him the completed
job to pick any final bones before he signs it off as perfect.
That is how it works now - on the first couple of jobs we did for this customer
we needed a little support, since switch-modes were new to us - but the circuits
mostly follow a pattern so we soon learnt to recognise where special attention
was required (FET drain/transformer/diode path, sense resistor tracking, emc
filtering etc).
Suggest you find a pcb designer/bureau that will work with you to establish the
way you would prefer thing done (if out of the ordinary) and specify everything
on the circuit (currents/voltages/sensitive areas etc).
Please remember the laws of physics - if you want 3mm (or more) creepage gaps
and 30 amp tracking it won't fit in the matchbox case your mechanical people
have already designed...
Geo
John Larkin
wrote:
>Do you layout your own boards or have a pc designer lay them out? I
I do power stuff, but picosecond layout is even worse. I stay *very*
close to my layout guy, and I often lay out critical sections, or an
example channel, myself. And I always check his intermediate versions
and the final layout.
Some PC designers can be hard to deal with. In Silicon Valley, there
is a 'cowboy' culture of PCB guys who think EEs are airheads and
sissies; these guys are hard to work with. The best PCB designers I've
known were women.
John
Kevin Aylward
But, of these women PCB designers, how many were good at PCB layout as
well?
Kevin Aylward
salesE...@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
Harry Dellamano
"Yzordderex" <yzord...@verizon.net> wrote in message
news:a69e22f6.03101...@posting.google.com...
I work with many different PCB designers, no problems, no face time.
I give them a Net list, board outline and PDFs of part outlines. They model
parts and place them inside the PCB outline. I reposition all critical
parts. It's about location, location, location for a design to be optimized
for thermal, EMI, shake + bake, low cost and noise free. Once all parts are
placed and gets my approval, he is given a list of critical Nets with copper
widths and spacing requirements. I check the Gerbers for these nets then
allow him/her to complete the remaining Nets and check their Gerbers daily.
Thermal spreaders and or layers, test points are then added.
I have never seen a PCB designer that could do a proper part placement in a
SMPS. Sometime they like to jump ahead with placement and rout. It all fits
but I don't want to test it.
Sounds involved but all happens very quickly. I can do a 500 part design,
critical part placement in one day. You must realize which parts they can
place with some simple rules. If you do nothing else you should place or
have rules for all capacitors and then check their wiring. They must have
the lowest Z at highest frequency so lead length is important. The PCB is
the single most critical component and requires at least 10% of the design
effort.
works for me
harry
Bill Sloman
> Do you layout your own boards or have a pc designer lay them out? I
> suffer from extream anxiety when I have to deal with some pcb
> designers.
In general, my employers have arranged things so that printed circuit
drafts-persons have laid out my circuit designs.
The very fast or very precise stuff, you have to work fairly closely
with them, but with a good drafts-person, a page or so of notes, and
some layout notes on the circuit diagram ("keep this track as short as
possible and well away from track X") gets you most of the way.
We'd check the layout after the drafts-person had done a placement and
again when the basic tracking had been done, and then go over the
board effectively checking the layout agains the net-list, more to
make sure that we looked at every trace than to confirm that the
layout followed the circuit diagram.
I have laid out a couple of small, fast boards, and I don't think that
I did any better than a good draftsman would have done.
I've also seen - and fixed - some truly appalling layouts. there are
quite a few mediocre drafts-persons around.
England being what it is. I mostly worked with draftsmen. The one
female drafts person I can recall was very good. Her father, who also
worked for Cambridge Instruments as an instrument maker, was both
exceptionally bright and exceptionally careful, and I imagine that she
was better than the average female drafts-person.
-----
Bill Sloman, Nijmegen
Rene Tschaggelar
In case you have advanced or field specific knowledge that you
cannot expect from a pcb designer, then you have to communicate it.
If that doesn't work out for one reason or another, then do the
pcb's yourself. A few weeks of learning plus a few grand for the
software should get you going.
Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
Harry Dellamano
I am interested on how R.Legg <le...@magma.ca> would answer this question.
Please tell us in some depth. Should be helpful to us all.
regards
harry
Spehro Pefhany
<har...@tdsystems.org> wrote:
>
>I work with many different PCB designers, no problems, no face time.
> I give them a Net list, board outline and PDFs of part outlines. They model
>parts and place them inside the PCB outline. I reposition all critical
>parts. It's about location, location, location for a design to be optimized
>for thermal, EMI, shake + bake, low cost and noise free. Once all parts are
>placed and gets my approval, he is given a list of critical Nets with copper
>widths and spacing requirements. I check the Gerbers for these nets then
>allow him/her to complete the remaining Nets and check their Gerbers daily.
>Thermal spreaders and or layers, test points are then added.
> I have never seen a PCB designer that could do a proper part placement in a
>SMPS. Sometime they like to jump ahead with placement and rout. It all fits
>but I don't want to test it.
> Sounds involved but all happens very quickly. I can do a 500 part design,
>critical part placement in one day. You must realize which parts they can
>place with some simple rules. If you do nothing else you should place or
>have rules for all capacitors and then check their wiring. They must have
>the lowest Z at highest frequency so lead length is important. The PCB is
>the single most critical component and requires at least 10% of the design
>effort.
>
>works for me
> harry
Nice. I think this is advice you can take to the bank with *any* kind
of circuit that has critical analog bits..
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com