Author Topic: PCBWAY embedding resistors and capacitors  (Read 670 times)

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Offline Capernicus

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PCBWAY embedding resistors and capacitors
« on: January 21, 2022, 04:48:02 am »
So if you were getting a PCB made by PCBWAY,    could you actually put the capacitors and resistors on the pcb design itself. (in copper.)
So there is no plotting to be done.

Im looking for 30 ohm resistance for the resistor,   and 100 fempto farads for the capacitor.    is it possible?
 

Offline T3sl4co1l

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Re: PCBWAY embedding resistors and capacitors
« Reply #1 on: January 21, 2022, 05:28:19 am »
30 ohms is a lot to ask from copper, at normal design rules.  100fF is fine.

The tempcos of both are rather extreme: copper is, what is it, a bit worse than PTAT I think?  And the capacitance is whatever the laminate is, so depends on whether you're doing sandwich (traces above/below) or adjacent (traces on same layer), and obviously there's no shielding to surroundings.

The other reason Cu sucks for resistance is its inductivity.  Typically reactance dominates above 10-100kHz, even for structures that attempt to cancel out inductance (e.g. hairpin loops instead of spirals).  So it's hopeless as a current-sense resistor (where the small resistances might prove useful) in switching circuits.

Or did you mean embedded components as in carbon ink, chips embedded in the stackup, etc.?  Which are also possible -- but I can't imagine a proto fab doing such esoterica..?  I mean unless that's what they've said they can do, I haven't checked anything.

Tim
Seven Transistor Labs, LLC
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Offline Capernicus

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Re: PCBWAY embedding resistors and capacitors
« Reply #2 on: January 21, 2022, 05:34:43 am »
I just mean copper,   and preferable single sided.   I'm expecting not being able to print carbon at PCBWAY.
Laminating and sandwhich a top and bottom for the caps,  that sounds cool.  just lining them up, have to be a little careful.
30ohm resistance is more for nichrome than copper.      So the caps are a go, and the resistors are a nogo.
Especially if you wanted to support say 300 watts,  itll blow the trace easily.

There might be something I can do tho, if I make it an AC system instead of a DC system,  and I use caps to limit the amps instead of resistors.

Thanks for the advice.
 

Offline PKTKS

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Re: PCBWAY embedding resistors and capacitors
« Reply #3 on: January 21, 2022, 12:39:29 pm »
hmmm this is that blending point where  we start considering COB and not PCB (discrete) anymore..

And COB.. you know..  if anything fails or deviates... it goes landfills... :o

Paul
 
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Offline Capernicus

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Re: PCBWAY embedding resistors and capacitors
« Reply #4 on: January 21, 2022, 08:15:28 pm »
hmmm this is that blending point where  we start considering COB and not PCB (discrete) anymore..

And COB.. you know..  if anything fails or deviates... it goes landfills... :o

Paul

Its a precursor to making your own asics,   even tho there is plottable components small enough to work as well,  but its too much work involved IMO.
 


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