6 ms·

In 2024, if your resistor vendor has even 5% tolerance, you need to find another vendor.

rchowe 2y ago
Thin-film resistor design engineer here! It's dependent on value and geometry -- if you order a 0.5 ohm resistor the meters on our trimming lasers only go down to 20 mΩ and you're getting a 5% part at best.
- alright2565 2y ago
  What about shunt resistors? I can pretty easily get a 1% 5mΩ resistor, but they don't look to me like they are constructed in the same way as a generic resistor.
  - KennyBlanken 2y ago
    They're made in a bunch of ways but the general principle is "the stuff inside is much lower resistance than what's normally used."
- SAI_Peregrinus 2y ago
  And that's why the really precise resistors are so damn expensive. E.g. VPG makes a 10k 1/5W 0.001% tolerance ±0.2ppm/°C, but they're $116 each with a minimum order quantity of 25 on DigiKey (so $2900 minimum purchase). They've got a really expensive meter for their trimming setup!
  - galaxyLogic 2y ago
    I see. I guess that's why high-end audio is so expensive
    - atoav 2y ago
      As both a sound and electrical engineer I think most high end audio electronics is bullshit. If you know what you're doing a 50 cent opamp will give you results that are beyond what a human could identify in a double-randomized blind test. Same goes for comparing two rusty pieces of wire against highly pure copper speaker cables. For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense. For audio applications 1% resistors are fine. You can use still affordable 0.1% in places where you truly care. Below that it is getting ridiculous, as the influence of harder to match things will take over. Things like speakers or the room they are placed in. How about the speed of sound changing with air temperature and humidity? You better have a room that has uniform and stabilized air temperature and humidity. A big part of the audiophile game is about psychological impact and the joy of personalized optimization. I spent a lot of money on audio equipment and a lot of time on researching it myself. It is an interesting thing. But in the end it is also physics that are interpreted by your brain and I can't help but feel bad for people who need to (incoming hyperbole) turn every part of their setup into gold in order to be able to enjoy listening to their equipment as music passes through it.
      - mschuster91 2y ago
        > For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense. It's hard to find XLR (or even TRS) balanced connectors on most non-professional (=TV studios, expensive conference room setups, DJs/clubs/similar venues) equipment.
        frabert 2y ago
        We're talking audiophiles, it's not like they're trying to cheap out.
        atoav 2y ago
        Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays. I think this is more of a cultural divide than anything, with tradition being a big part of it. In the olden days balanced I/O had to be done using specialized transformers. Unless you got really expensive well wound ones these could degrade your signal significantly — that might've contributed to a bad rep in audiophile circles. But today you can balance or unbalance electronically with indistinguishable fidelity and... ironically a lot of the analog "warmth" people love in old recordings came from the transformer on the inputs of old mixing desks. There is really no reason to use unbalanced today other than being really pressed for money or running so short cables that it won't matter - and even then you could do better than RCA connectors.
    - SAI_Peregrinus 2y ago
      Ha! No, they're not using metrology resistors, just ripping people off.
      - galaxyLogic 2y ago
        High-end audio is a status-symbol. It shows that not only you are rich, but that you are also sophisticated. But what happens if you don't like the music coming out of your stereo? No gold-plated connectors can cure that.
  - rchowe 2y ago
    I'm not as familiar with foil resistors, but if you apply the same rules as thin film I would expect that you could trim this with a normal meter (the ± is 0.1 ohms) and the major cost driver is laser trim time and the space cost of some extra geometry on the resistor to support the tight tolerance (i.e. more fine trim features than standard). I believe Vishay's ±0.2ppm/°C TCR is a materials science process specific to one of the companies they own, so that is also a reason they can charge quite high prices. If you don't need that kind of TCR (i.e. your part is not going to space) the price should go down considerably for a thin film NiCr resistor (5 ppm - 25 ppm). There is actually a lot more direct sales and custom design volume than I would have expected when I started in this industry, so what you see on Digi-Key is not the entire market.
gmueckl 2y ago
AFAIK, it used to be that parts binning was used to sort parts by tolerance. So the 5% bin wouldn't include <1% parts because those were already selected into the 1% bin in the factory and so on. Is it still like this?
- rchowe 2y ago
  It depends on the component and the company/process. Laser trim time for thin film is a significant cost-driver, so if possible you want to aim for a specific value and reject or bin-sort the rest out. My company only makes 1% tolerance resistors by laser trimming.
- bsder 2y ago
  Mostly, no. Nobody except for expensive precision resistor companies are actually measuring resistors more than statistically. The resistors are manufactured so that they are "guaranteed by manufacturing" such that the outliers are 1%, 5%, 10%, etc. And they do statistical checks on batches, but not really looking for the 10% outlier (which is stupendously rare and very difficult to catch) but looking for slight drifts off nominal (which are much easier to spot) which would result in more outliers than expected. As such, if you measure resistors, you tend to find that you get really close to nominal--much closer than you would expect for 10%, say. Resistors are so cheap that binning simply doesn't make economic sense.
  - LeifCarrotson 2y ago
    Is this how LEDs are binned as well, or are they powering each node on the wafer before packaging? They're orders of magnitude more expensive than resistors, so I figure they might... There are all kinds of crazy parameter variations in optoelectronics. I understand that resistors are really close to nominal because the manufacturer's ability to tune the process controls are so much better than the standard 5% and 10% bins, but it seems that LED manufacturing is way more difficult and they can't always tune the process to get exactly what they want.
    - mastax 2y ago

Thin-film resistor design engineer here! It's dependent on value and geometry -- if you order a 0.5 ohm resistor the meters on our trimming lasers only go down to 20 mΩ and you're getting a 5% part at best.

alright2565 2y ago
What about shunt resistors? I can pretty easily get a 1% 5mΩ resistor, but they don't look to me like they are constructed in the same way as a generic resistor.
- KennyBlanken 2y ago
  They're made in a bunch of ways but the general principle is "the stuff inside is much lower resistance than what's normally used."
SAI_Peregrinus 2y ago
And that's why the really precise resistors are so damn expensive. E.g. VPG makes a 10k 1/5W 0.001% tolerance ±0.2ppm/°C, but they're $116 each with a minimum order quantity of 25 on DigiKey (so $2900 minimum purchase). They've got a really expensive meter for their trimming setup!
- galaxyLogic 2y ago
  I see. I guess that's why high-end audio is so expensive
  - atoav 2y ago
    As both a sound and electrical engineer I think most high end audio electronics is bullshit. If you know what you're doing a 50 cent opamp will give you results that are beyond what a human could identify in a double-randomized blind test. Same goes for comparing two rusty pieces of wire against highly pure copper speaker cables. For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense. For audio applications 1% resistors are fine. You can use still affordable 0.1% in places where you truly care. Below that it is getting ridiculous, as the influence of harder to match things will take over. Things like speakers or the room they are placed in. How about the speed of sound changing with air temperature and humidity? You better have a room that has uniform and stabilized air temperature and humidity. A big part of the audiophile game is about psychological impact and the joy of personalized optimization. I spent a lot of money on audio equipment and a lot of time on researching it myself. It is an interesting thing. But in the end it is also physics that are interpreted by your brain and I can't help but feel bad for people who need to (incoming hyperbole) turn every part of their setup into gold in order to be able to enjoy listening to their equipment as music passes through it.
    - mschuster91 2y ago
      > For some reason audiophiles will use darn massive gold (or silver) RCA connectors instead of something like a balanced connection that would actually make sense. It's hard to find XLR (or even TRS) balanced connectors on most non-professional (=TV studios, expensive conference room setups, DJs/clubs/similar venues) equipment.
      - frabert 2y ago
        We're talking audiophiles, it's not like they're trying to cheap out.
        atoav 2y ago
        Even a 80 Euro Berhinger USB audio interface has balanced outs nowadays. I think this is more of a cultural divide than anything, with tradition being a big part of it. In the olden days balanced I/O had to be done using specialized transformers. Unless you got really expensive well wound ones these could degrade your signal significantly — that might've contributed to a bad rep in audiophile circles. But today you can balance or unbalance electronically with indistinguishable fidelity and... ironically a lot of the analog "warmth" people love in old recordings came from the transformer on the inputs of old mixing desks. There is really no reason to use unbalanced today other than being really pressed for money or running so short cables that it won't matter - and even then you could do better than RCA connectors.
  - SAI_Peregrinus 2y ago
    Ha! No, they're not using metrology resistors, just ripping people off.
    - galaxyLogic 2y ago
      High-end audio is a status-symbol. It shows that not only you are rich, but that you are also sophisticated. But what happens if you don't like the music coming out of your stereo? No gold-plated connectors can cure that.
- rchowe 2y ago
  I'm not as familiar with foil resistors, but if you apply the same rules as thin film I would expect that you could trim this with a normal meter (the ± is 0.1 ohms) and the major cost driver is laser trim time and the space cost of some extra geometry on the resistor to support the tight tolerance (i.e. more fine trim features than standard). I believe Vishay's ±0.2ppm/°C TCR is a materials science process specific to one of the companies they own, so that is also a reason they can charge quite high prices. If you don't need that kind of TCR (i.e. your part is not going to space) the price should go down considerably for a thin film NiCr resistor (5 ppm - 25 ppm). There is actually a lot more direct sales and custom design volume than I would have expected when I started in this industry, so what you see on Digi-Key is not the entire market.

gmueckl 2y ago

AFAIK, it used to be that parts binning was used to sort parts by tolerance. So the 5% bin wouldn't include <1% parts because those were already selected into the 1% bin in the factory and so on. Is it still like this?

rchowe 2y ago
It depends on the component and the company/process. Laser trim time for thin film is a significant cost-driver, so if possible you want to aim for a specific value and reject or bin-sort the rest out. My company only makes 1% tolerance resistors by laser trimming.
bsder 2y ago
Mostly, no. Nobody except for expensive precision resistor companies are actually measuring resistors more than statistically. The resistors are manufactured so that they are "guaranteed by manufacturing" such that the outliers are 1%, 5%, 10%, etc. And they do statistical checks on batches, but not really looking for the 10% outlier (which is stupendously rare and very difficult to catch) but looking for slight drifts off nominal (which are much easier to spot) which would result in more outliers than expected. As such, if you measure resistors, you tend to find that you get really close to nominal--much closer than you would expect for 10%, say. Resistors are so cheap that binning simply doesn't make economic sense.
- LeifCarrotson 2y ago
  Is this how LEDs are binned as well, or are they powering each node on the wafer before packaging? They're orders of magnitude more expensive than resistors, so I figure they might... There are all kinds of crazy parameter variations in optoelectronics. I understand that resistors are really close to nominal because the manufacturer's ability to tune the process controls are so much better than the standard 5% and 10% bins, but it seems that LED manufacturing is way more difficult and they can't always tune the process to get exactly what they want.
  - mastax 2y ago