0Ω Resistors, Tolerances, and Materials...

Thread Starter

Yaakov

Joined Jan 27, 2019
3,190
So in another thread I was led to measure (using 4-wire) the resistance of a 0Ω through hole "resistor". I got 17mΩ across the resistor body, and about 5mΩ for each lead. @Ian0 mentioned he was using a 10mΩ sense resistor, which is of course, about what leads are in my case.

I decided to dig up a datasheet... So, there isn't a separate one for the 0Ω links in the various resistor series, but, you can get them in various tolerances (!) and a carbon film or metal film.

What?

I can only assume that's to make them match the other resistor in the same product line... right?

What is a tolerance for 0Ω? Is the 1% closer to 0 than the 5%? Does it ever go below zero by some percentage? If so, can we sort those out and use them as magic amplifiers?

Questions must be answered!
 

Thread Starter

Yaakov

Joined Jan 27, 2019
3,190

sagor

Joined Mar 10, 2019
439
Not all zero ohm jumpers are created equal, some are more equal to zero than others. :)

It usually costs more to get nothing.
In practice, there is no such thing as zero ohm resistance, unless you get to absolute zero with some super conductor. All "zero" ohm resistor, jumpers, or even bare wire have some resistance.. It might be very low, but never zero.
So why worry about it?
 

nsaspook

Joined Aug 27, 2009
8,394
In practice, there is no such thing as zero ohm resistance, unless you get to absolute zero with some super conductor. All "zero" ohm resistor, jumpers, or even bare wire have some resistance.. It might be very low, but never zero.
So why worry about it?
Usually the requirement is obviously not absolute zero but 'zero' in reference to other circuit elements as needed for proper operation parameters.

It depends on the application. I've some motor control designs that have H-bridge 'zero' ohm motor wire SMD jumpers that have peak motor current requirements that require specific types of 'zero' jumpers while other types of 'zero' jumpers (like in SMD resistor assortments) are interconnects for low current circuit wiring there the actual 'zero' value is much less critical.
 

MrChips

Joined Oct 2, 2009
23,568
Once I had to build an instrument to test automotive flasher relays for a major after-market automotive supplier.
I had to guarantee that the interconnects were zero ohms. I went to a lot of effort to fulfill that requirement.
 

ronsimpson

Joined Oct 7, 2019
1,242
When you make a resistor this size: [] then the label "0" almost fits. But "0.072 +/-5%" does not fit.
Labeling = "This is he lowest value we can make for this low price."
Consider "0 ohms" is the same as the price $0.00. When I get 5000 resistors at a time from China the price/resistor is also "0".
 

Ian0

Joined Aug 7, 2020
2,289
Back in the day, before zero ohm links were popular, most people cut a piece of wire off a spool put two right angle bends in it and soldered it to the board. Assuming 0.5mm diameter copper wire, and 0.4” between holes and a 1.6mm thick pcb that would be 1.15mΩ.
However, we used to use 10Ω carbon film resistors, and try to make sure we tracked the board so that they were in logic tracks, or the positive supply, where they improved the decoupling. Resistors <10Ω were a higher price.
There used to be two sorts of zero ohm link, those made out of a solid piece of metal, and those made like a resistor on a ceramic cylinder with a thin layer of metallising.
The first type would take a lot of current, the second type . . . . .wouldn’t. Some supplies told you which type you would get, and some didn’t.
I remember a large product recall to change the second type for the first.
 

nsaspook

Joined Aug 27, 2009
8,394
Back in the day, before zero ohm links were popular, most people cut a piece of wire off a spool put two right angle bends in it and soldered it to the board. Assuming 0.5mm diameter copper wire, and 0.4” between holes and a 1.6mm thick pcb that would be 1.15mΩ.
However, we used to use 10Ω carbon film resistors, and try to make sure we tracked the board so that they were in logic tracks, or the positive supply, where they improved the decoupling. Resistors <10Ω were a higher price.
There used to be two sorts of zero ohm link, those made out of a solid piece of metal, and those made like a resistor on a ceramic cylinder with a thin layer of metallising.
The first type would take a lot of current, the second type . . . . .wouldn’t. Some supplies told you which type you would get, and some didn’t.
I remember a large product recall to change the second type for the first.
They still make at least two types of 'zero' ohm links...
https://www.vishay.com/docs/30192/wsl-9.pdf
Current capacity starts at 45A
WSL0603…9 0603 45 1.9 0.00025
WSL0805…9 0805 50 4.8 0.0002
WSL1206…9 1206 65 16.2 0.0002
WSL2010…9 2010 75 38.9 0.0002
WSL2512…9 2512 200 63.6 0.0002

https://forum.allaboutcircuits.com/threads/0o-resistors-tolerances-and-materials.179554/post-1636557
 

BobaMosfet

Joined Jul 1, 2009
1,780
So in another thread I was led to measure (using 4-wire) the resistance of a 0Ω through hole "resistor". I got 17mΩ across the resistor body, and about 5mΩ for each lead. @Ian0 mentioned he was using a 10mΩ sense resistor, which is of course, about what leads are in my case.

I decided to dig up a datasheet... So, there isn't a separate one for the 0Ω links in the various resistor series, but, you can get them in various tolerances (!) and a carbon film or metal film.

What?

I can only assume that's to make them match the other resistor in the same product line... right?

What is a tolerance for 0Ω? Is the 1% closer to 0 than the 5%? Does it ever go below zero by some percentage? If so, can we sort those out and use them as magic amplifiers?

Questions must be answered!
And the monks chant on... ohm..... ohm..... ohm.......
 
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