EE's who do PCB Layout



I've almost always had a CAD guy to do mechanical drawings, design really, and to lay out PCBs for me. I even draw schematics on paper and let him create the library parts and enter the schematic. We discuss placement, routing, thermal issues, whatever, and he lays out the board and does the whole package: schematic, pcb, fab drawing, assembly drawings, BOM, gerbers, PDF files, front-panel fab and artwork. A decent density multilayer board may take him 3 or 4 weeks for the whole package, and that saves me a lot of time.
I do review the layout in process and check/tweak the final layout before we gerber/release it.
John
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I design circuits and layout PCBs. I know I don't do as good a job as a good PCB layout engineer would do. I know I don't know the CAD tools as well and am less efficient than a good PCB layout engineer who uses them every day. I know quite a lot about PCB manufacture, footprints and data preparation etc. I know I don't know as much as I should.
I think you grossly underestimate the amount of knowledge and skill required to be a good PCB layout engineer.
The idea that it would be more efficient for design engineers (without significant previous experience) to layout their own PCBs to avoid information transfer between design and layout engineers is almost farcical. Unless your PCB layout requirements are very modest and/or the layout engineers you have are rubbish.
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He probably does, but you might grossy overestimate how many "good PCB layout engineers" actually exist out there, especially if you are in Podunk, Nowhere. :-)
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Back when I did EE for a living, we had a layout group that did the layouts for the official boards, but we also had Cadstar for smaller boards, and we did those ourselves. At least, I did. The layout group was often too busy to "get to it" in a reasonable time.
These days, I do all my own layouts, but only because I don't do EE for a living any more (I do software for a living now). I find that I work on the schematics and layout at the same time during the second half of the project (once there's enough schematics to even start the layout), as the needs of the layout may require changes in the schematics, mostly pin swapping.
Of course, the fact that I'm one of the authors of PCB makes me biased ;-)
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I can be, but only if the design engineer is not only good at PCB layout, but efficient as well. Being a good design engineer does not imply one is also good at PCB design, nor efficient for that matter. You can get superb designers who can't operate the software tools to save their life.

Yes it is, for better and for worse. Every company is different though.
I've found it fairly rare where *every* design engineer in a company will lay out their own board. Usually you end up with either your own in-house PCB group, or the PCB work gravitates toward the engineer with the best PCB skills, or the work is simply contracted out (fairly common for very large designs). Not every company likes to have their design engineers tied up for several weeks laying out some huge board.
Dave.
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Your workplace sounds exactly like the various commercial places that I've worked.
When I've had the chance I've always checked the printed circuit layouts agains the schematic - not so much to make sure that all connections are correct, because printed circuit draftspersons can be relied on to get that right, but so I get to see where every last track goes, where things can go wrong.
Most of the places I've worked wouldn't let me spend the time required.
On one occasion, the experts in the drawing office knew that the order of layers within a multilayer board didn't matter, and ignored my explicit instructions about where to put the various ground planes in a board where a lot of high speed signals were being routed along transmission lines. It took as quite a while to find out why the board wasn't working right.
When I was working at Nijmegen University I was able to get my hands on a copy of their printed circuit layout program and did lay out a couple of sensitive boards. It worked out fairly well. The boards worked, and it didn't take me all that long to lay them out. I didn't bother laying out less sensitive boards - the draftsmen paid attention to the constraints I put in the layout and produced tidy layouts that worked fine.
-- Bill Sloman, Nijmegen
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BJ wrote:

Occasionally I have done so, but it is inefficient. Unles you do it often you're usually not good at it. Better use of my talents is for me to direct the designer.
Mark Walter, EE
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BJ wrote:

Using EEs to lay out pcbs would tie up the EEs with what many view as boring work that they're not experts at.
And yes, it's not an ideal world. Until pcb layout guys become top-class EEs they'll continue to goof up with indifferent layouts. In that respect the EE should provide decent initial guidance about specific layout considerations.
I don't see any 'perfect world' hppening anytime soon in this regard.
Graham
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BJ wrote:

BJ (..what a nick..), I'm completely doing my own pcb's through to the prototypes and perhaps small series of 10 or so. There is so much knowledge in doing the pcb's, that is rather hard to transport. The usual schematic and layout tools do not provide any support for such knowledge. Just consider the GND symbol on the schematic. It stands for an equal potential. Yet, it has to be treated differently whether you're doing sensitive sensing in a high current environment or in RF.
Thus a design of mine is delivered as stuffed pcb, and an optional schematic is just a reference.
Rene
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Yes, I do everything too (circuit design, PCB layout, prototype build, testing, software). It seems to work OK. One advantage is that I can easily change things around to suit the layout, for example re-allocate microcontroller I/Os, without conferring with someone else each time.
--

John Devereux

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Rene Tschaggelar wrote:

I just figured that I'm one of the few doing everything myself. We don't have Sole-Layouters here, or I haven't heard of them.
Rene
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You are not alone. The PCB is an unique component in the RF system; PCB's I'm familiar with often contain a lot of printed filters and inductors.
I work with a lot of engineers who themselves layout PCB's, do RF design, and DSP development. Sometimes in the same day. I usually do my own PCB layout in the RF signal chain on anything above 3 GHz.
Frank Raffaeli
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I mostly do my own layouts. The main reason is that while doing the layout changes (pins swaps) in the circuit diagram may lead to more optimal placement and circuits which are easier to route.
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On Sun, 05 Aug 2007 07:14:58 GMT, snipped-for-privacy@puntnl.niks (Nico Coesel) wrote:

We often let our layout guy pick pins, especially for mass connections, like a dozen ADCs connecting to one BGA FPGA. We'll just explain the general concept and let him do the massive amount of work to place the parts, pick the pins, and route the traces. He got 12 12-bit ADCs into a BGA, all on layer 1, with no vias or crossovers. It's beautiful, like a butterfly wing.
http://s2.supload.com/free/V660x2.jpg/view /
http://s2.supload.com/free/MVC-001X.JPG/view /
We also sit down with him, early in the design, and negotiate density, number of channels, placement, area, thermal issues, stuff like that. Sometimes he surprises us by commiting to get more on a board than we thought possible. Once we have a placement, sometimes we can assign pins at the initial schematic level, minimizing vias and layers. But he's just a few steps away, and we understand each other, so this sort of interaction works. If my only choice was an outside service, or a separate department, I'd be a lot more likely to do it myself.
John
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I worked my last year in high school and freshman year in college as a pcb layout artist (back in 'dem red/blue tape and donuts days) and actually enjoy the layout as much as the design. Besides, there are always minor design improvements I can make on the fly in the layout process.
Jim
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RST Engineering (jw) wrote:

That can be especially gratifying when using a fully integrated CAD where a change in layout flows back to the schematic. "Oh, let's use singles gates instead."
Although me and my layouter have also easily done that, using totally different CAD software.
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Most better layout tools will also automatically swap (equivalent) gates and pins if asked to do so; I've found this a very nice little time saver when you're after a "clean" layout.
I do find the single-gate TinyLogic parts quite attractive, though...
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Joel Kolstad wrote:

Pretty much all allow gate swaps even across devices. Some go a lot farther: You can decide to split an inverter six-pack into singles if that prevents you from having to go to two more layer. Or go to a discrete solution if you find the logic chip version somehow doesn't pan out.

Yes. But a bit costly.
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The intergrated suites, yes, but if you're using, e.g., PADS layout with just a netlist for input (a not-at-all uncommon flow), it has no knowledge of what's "swappable" to begin with, so you end up having to do it back on the schematic and exporting the netlist again. This can takes long enough that some layout guys just don't bother; they'd rather add some more vias and have some ugly traces.

That's rather nice -- I take it Eagle does this?

Indeed; it's almost surprising that some Asian company hasn't come out with a line of single-gate ICs selling them for pennies in the thousands. Especially since they could use older, slower fab processes -- I'm almost never looking at TinyLogic for speed, yet that seems to be one of the main sales points you get about them. (Not that speed is bad, just that for every 7Z00 sold, I imagine under 10% actually require the speed provided.)
---Joel
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Joel Kolstad wrote:

That's where rapid communication comes into play. My layouter and I are in constant email contact during layout and I always prepare a brief write-up for him. Like "U3, 6, 23, 15, 23 section swap ok but keep those in U15 within same chip". So he even knows before the layout what he can swap. Then at some point he sends me back what he did swap and I update the schematic. However, I tend to draw schematics "layout-friendly" so he usually finds that the allocation is already close to what he'd have liked. Hindsight section swaps in an Eagle schematic are a breeze, just a few mouse clicks.

Yes, but I never do that myself because I don't do layouts. However, others have said it's pretty easy, AFAIR you just have to reconnect in the schematic so it looks clean.

I find them to be a bit on the expensive side so I haven't used tiny logic yet on anything that went into production. Most of my stuff is quite cost critical.
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