Timeline for How to make a very thin plate with some resistance
Current License: CC BY-SA 4.0
23 events
| when toggle format | what | by | license | comment | |
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| Dec 15, 2023 at 16:58 | answer | added | Mattman944 | timeline score: 2 | |
| Dec 15, 2023 at 15:23 | comment | added | mabeco | @Mattman944 was searching like you said (think film resistive paste). For the paste itself didn't find much information, more about resistors like this: elprocus.com/thick-film-resistor. But it seems that the resistive material is quite "small" compared to the whole resistor. The metals on the edges create additional electrical field than what I was trying to study. | |
| Dec 15, 2023 at 15:21 | comment | added | Hearth | @mabeco Not anything a standard PCB fab is equipped to work with. A wafer fab could probably do a 1 μm thick (or even thinner) layer of ti-tungsten, though. | |
| Dec 15, 2023 at 15:16 | comment | added | mabeco | @Hearth I believe you are right, it's very difficult to be smaller than 3 mils. Do you know if instead of copper it could be another material with higher resistivity? | |
| Dec 15, 2023 at 12:58 | comment | added | Hearth | @mabeco It can't be 5 μm wide--most PCB fabs won't go thinner than about 3 or 4 mils, and that gets expensive. | |
| Dec 15, 2023 at 11:05 | comment | added | Mattman944 | Graphite might work, but it would be thicker than you want. There was a video online of someone demonstrating the hall effect using a simple setup. I decided that it was bogus, but my interest was piqued and I attempted to create my own demonstration. I needed a rectangular piece of resistive material similar to what you want. I bought a doped silicon wafer, but it is nearly impossible to make electrical contact with it. Thick pencil lead, like a carpenter would use, was the most promising, but my demonstration was mostly a failure. amazon.com/gp/product/B002FX2RPG | |
| Dec 15, 2023 at 10:53 | comment | added | Mattman944 | Search for thick film resistive paste. Several substrates are used, Alumina is common. But, it is doubtful that you will be able to lay down a consistent layer of paste without special equipment. Your best bet would be to collaborate with a University, if you can find one that still has a working thick-film lab, and your project has enough scientific interest to get a professor to help you. My thick-film lab course was in 1980. | |
| Dec 15, 2023 at 10:21 | comment | added | mabeco | @Hearth maybe you have a good idea. But if the "height" of the copper is ~35um and width of the trace is ~5um (and I guess I could have a trace distance of another ~5 um) I think I would need -3m trace to get to 180 ohms. So maybe if it is possible to reduce the trace width to 1um...could get L=63cm...not bad. Just a note: I don't want to zigzag...it needs to be straight | |
| Dec 15, 2023 at 10:14 | comment | added | mabeco | @ glen_geek maybe I misunderstood, but as far as I could tell, CD/DVD have aluminum which, although might be very thin, is still a very good conductor so reaching 180 ohms could be hard | |
| Dec 15, 2023 at 10:12 | comment | added | mabeco | @Tim Williams I agree with you and there is a 99.99999....999% chance I won't discover anything new. Its just an experiment. | |
| Dec 15, 2023 at 10:10 | comment | added | mabeco | @Mattman944 Thank you for the suggestion, but how could I go around to purchase that thick film? Did a quick google search and did not come up with many answers. | |
| Dec 15, 2023 at 10:09 | comment | added | mabeco | @periblepsis yes, I think so. The Si with rho = 0.01 that I saw as a doped wafer (resistivity would be much higher if it was just pure Si) | |
| Dec 15, 2023 at 10:06 | comment | added | mabeco | @Jason + jsotola I edited the question (its a solid box acting as a resistor) | |
| Dec 15, 2023 at 7:58 | history | edited | mabeco | CC BY-SA 4.0 |
corrected formulas, explained its a solid box
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| Dec 15, 2023 at 5:08 | comment | added | Hearth | The copper on a standard PCB is 35 μm thick, so if you make L very long or W very narrow you can get 10 Ω out of that. It's about 0.5 mΩ/⧠, so your L/W ratio needs to be about 20,000. For a 6-mil wide trace (easy for most PCB fabs), that's 120 inches, which you could achieve on a reasonably sized board by simply zigzagging back and forth a bunch of times. | |
| Dec 15, 2023 at 4:13 | history | edited | Dave Tweed | CC BY-SA 4.0 |
fix typos, formatting
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| Dec 15, 2023 at 1:43 | comment | added | glen_geek | Sounds somewhat like a CD or DVD...very thin aluminum disk sandwiched in clear plastic. The trick will be to gain access to the aluminum. I don't know its thickness, and hence resistivity is unknown. | |
| Dec 15, 2023 at 1:24 | comment | added | Tim Williams | What do the dimensions matter to the electric field? The field within the box is independent of the dimensions, scaled appropriately. You can probe the field within a scaled-up box much more easily. If the purpose is field outside the box, that can be implemented with any finite resistance, and roughness of the box probably doesn't matter as much or at all, i.e. consider a cylindrical or wirewound figure instead. | |
| Dec 15, 2023 at 0:54 | comment | added | Mattman944 | Thick film technology would be a possibility. The substrates are thin. The resistive paste is available in many different conductivities. You could put a thin edge of conductive paste to allow the edges to be soldered. Unfortunately, you will have difficulty applying the paste evenly without the proper equipment. | |
| Dec 15, 2023 at 0:27 | comment | added | periblepsis | You can get p-type or n-type wafers that will have a different \$\rho\$ than intrinsic silicon. Might consider that option. | |
| Dec 15, 2023 at 0:08 | comment | added | jsotola | what's inside the box? ... is there a lid? | |
| Dec 14, 2023 at 23:50 | comment | added | Jasen Слава Україні | the "box" is a void, or a solid | |
| Dec 14, 2023 at 23:18 | history | asked | mabeco | CC BY-SA 4.0 |