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My layout guy is struggling with this. Actually, he seems to be enjoying it.It has two D25 connectors, 130 relays, 49 polyfuses, and the usual FPGA and such. 8 layers, four of which will be 2oz copper.
gnarly PCB
Apr 11, 2024
Last reply: 2 years ago
6 Replies
It's a big PCB for sure.
Nasty layout program, looks like it's from the 90'ties
Switch to Altium?
Yes. It is supported on the ends.
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One customer wants to fly it and is rightly concerned about vibration. I'm working on that.
The Brat put up our new web site yesterday, and it includes the public announcement of our modular power system.
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The P940 system originated when a customer, on a zoom call, said "we hate power supplies."
It has pads and traces. Don't all layout programs do that?
It's PADS. We've been using it since the dos/floppy disk days. It works fine. I don't like the color scheme that my guy uses; we change the colors before we release the boards.
The schematic editor is excellent. It actually understands connections.
Very pretty with all those layers/colors !
Just put enough standoffs to hold it and should be fine.
Be careful of big ceramic SMT caps next to flex points.
boB
It's supported on the ends and is very flexy.
My plan is to add rubber weatherstripping strips to the chassis bottom and to and top cover, to damp resonances.
This feels good, nice and snug.
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This will go in a "flying test bed", basically an old 747 with three original engines and one DUT. Vibration will be mild, nothing like an F35.
Even so, beware. Those cards _will_ flex badly, and destroy the card to card connectors first. Fretting, maybe fracture. Depends. The card may be OK, but it too will fail eventually. BTDT. Or rather, I got the fixup job, in the 1970s.
Later, I've seen fretting due to cooling-fan vibration and tin-plated connector fingers destroy a midi-computer in the 1990s. Which is why people don't use tin plated connectors (even with some anti-whisker lead alloyed in) in such applications.
The two bumper weather strips don't look to be enough, especially when the top and bottom sheets flex outward. But edge clamps screwed to those sheets could work. Or some kind of crossbars passing between the circuit cards from top sheet to bottom sheet.
Joe Gwinn
OK, so the long board is supported, flex wise on the back panel. That's good.
How about on the front ? Anything holding it in, there ?
boB
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