I wonder what sort of copper to insulator ratio's they can get in printed transformer windings? They might be able to do better than round enamelled copper wire for low resistance windings.
Interesting stuff. The article does talk explicitily about plated windings for transformers, but the web-site doesn't seem to, though I'd imagine it to be an appreciable fraction of their business.
The point that extra-thick copper is a lot more resistant to thermal cycling came as a surprise - presumably it's thick enough to accommodate differential expansion by deformation, rather than cracking.
Advanced (4pcb.com) is also offering it. They got a new factory up in MN that does it, I think. I've heard of UPE before, too (owned by Methode, who make buses the conventional way).
The aspect ratios are pretty much the same, so don't count on making a 20 mil copper layer with 5 mil gaps and 5 mil prepreg. You might be able to get a 20 mil core between 10-20 mil copper, with 10-20 mil design rules.
Vias are similarly inflated, AFAIK, which probably means smaller ones are filled (or nearly so; probably want to check with them first to make sure it doesn't, say, trap electrolyte and corrode later on).
Tim
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Deep Friar: a very philosophical monk.
Website: http://seventransistorlabs.com
I'm not sure. I wonder about the skin effect losses in thick plated copper. As another factor, the rectangular cross-section gives a good fill factor, but not if the multilayer construction adds too much space between windings.
So, could be pretty interesting, but I'm not sure. Somehow I suspect it's too pricey for casual uses.
I don't know. I looked hard last year for bus bars and couldn't find any suitable standard products--they seem to have faded away. Lots of companies make custom, laminated, multi-conductor buss bars to your spec, but I couldn't find a simple, thru-hole part with 0.xxx"-spaced terminals.
I had to pass 1kA peak. Total resistance budget was 2 milliohms, with
1 milliohm allocated for the switch. Rather than mess around I spec'd a 3mm copper bar part, 12.5x30mm, surface-mounted. That served as conductor and connector, as posted here in sed. Commanded "closed," the proto measured 450e-6 ohms, terminal-to-terminal.
------| |------- |--| ---. copper bus bar, soldered to FR-4 .'.'.'| | \ \ \ \|--| \ \| /
------|_____|------- |--| ---'______________________. FR-4 | @ @ @|--|@ @ @ @ @ @ @ @ @ @ @ @ @ @| / |__@_@_|--|_@_@_@_@_@_@_@_@_@_@_@_@_@_|_____/ /________ |x| |__|--|__| |x x x x x x x x x x x x x / /x x x x x| | | /| |--| | | x x x x x x x x x x x x / /x x x x x | |x|/ |_|--|_| |x_x_x_x_x_x_x_x_x_x_x_x_/ /x_x_x_x_x_x| / '--' \ / / split nut . washer . . ||
That's right, not clamping the board. FR4 will cold flow over time, especially if it warms up. The contact pressure will fall, resistance will increase, and you can get thermal runaway.
Somebody makes a huge stamped metal tapped lug landing thing that solders to a PCB through a bunch of holes.
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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
I was thinking copper sheet etched or laser cut to the shape of the traces needed, might even be possible to place and solder with a more or less standard smd process
Yeah. There's also a stamped inverted U shape with a bunch of pins formed into the bottom, tapped on the flat top part. That solders.
The problem then becomes to get the current distribution right on the board, and not have some of the pins hog most of the current. That needs a finite-element-analysis program to do right, but you can cheat with a big sheet matrix of resistors in Spice.
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John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
I like wavy washers; they don't chew up the board as much.
Even better, solder in a bunch of fastons or a multipin Molex connector, and run a number of relatively smaller gage wires. It's more flexible, easier to handle, and the separate wire resistances tend to equalize the pin currents.
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John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
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