Proving the tolerance of a 0Ω resistor

Papabravo

Joined Feb 24, 2006
15,431
I just ran across this on a distributor's website.

"Thick Film Chip Resistors 1/16W,±1%,0Ω"

Think about it: what kind of instrumentation do you need to prove this spec
It is a kind of non sequitur in the sense that you cannot have a negative resistance, but also in the sense that trying place a relative tolerance on 0 is impossible. It might make more sense to use a statement about the value with respect to the next largest value. If the largest value is 10 milliohms, then 0 could be guaranteed to be between 0 & 5 milliohms.
 

MrChips

Joined Oct 2, 2009
23,054
+1
I know it is an impossibility but I am going to hazard a guess that anything lower than 1mΩ would meet specs.
 

nsaspook

Joined Aug 27, 2009
8,156
I just ran across this on a distributor's website.

"Thick Film Chip Resistors 1/16W,±1%,0Ω"

Think about it: what kind of instrumentation do you need to prove this spec
A computer printing database. Thick Film Resistors - SMD 0 ohm 5% 1/16W are cheaper.
 

GetDeviceInfo

Joined Jun 7, 2009
1,805
It
I just ran across this on a distributor's website.

"Thick Film Chip Resistors 1/16W,±1%,0Ω"

Think about it: what kind of instrumentation do you need to prove this spec
It’s likely a statement about the process, more than a specific unit. If My process can produce reliable accuracies over a range, It makes sense.
 

djsfantasi

Joined Apr 11, 2010
7,549
Or an improper way of automating product descriptions that assign text descriptions based on irrelevant input. Like all products that start with “1ZX” in their product Id number must be ±0.1% precision.
 
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Tonyr1084

Joined Sep 24, 2015
5,802
you cannot have a negative resistance
I don't remember what thread or who it was but someone was telling me it IS possible to have a negative resistance. Was given a technical paper on the subject, didn't keep it mostly because it was over my head (or under it maybe); but I can swear someone was defending negative resistance.
 

nsaspook

Joined Aug 27, 2009
8,156
I don't remember what thread or who it was but someone was telling me it IS possible to have a negative resistance. Was given a technical paper on the subject, didn't keep it mostly because it was over my head (or under it maybe); but I can swear someone was defending negative resistance.
There is nuance to negative resistance. https://en.wikipedia.org/wiki/Negative_resistance

There is no real "negative resistor" but there is an electrical property called negative resistance.
 

MrChips

Joined Oct 2, 2009
23,054
There is such a real thing as negative resistance.
A tunnel diode exhibits negative resistance in a portion of its I-V characteristic curve.
A circuit that has negative resistance is used for start/run/stop control in DC motors.
 

hrs

Joined Jun 13, 2014
303
Pedantic noob here. In the case of a tunnel diode wouldn't that be a negative differential resistance? For a truly negative resistance I would expect the current to become negative, ie. reverse.
 

schmitt trigger

Joined Jul 12, 2010
412
These are the types of components that over unity engineers use to design their products. :p

Now seriously. This is the result of companies having a junior intern writing spec sheets.
 

vanergr

Joined Nov 23, 2020
3
Which means if you measure anything other than zero the part is out of spec.
Well not necessarily. It depends where is it placed, the accuracy of the instrument and the conditions at the time of measurement.
If you use a common DMM it's most likely to get more than the 0 ohm since the leads have their own impedance. The more proper way would be using kelvin clips and a high accurate resistor measurement meter, like BK's DC Resistor meters. or to place the resistor in a Wheatstone bridge. Also 0 ohm resistors are used as isolation resistor in data lines on pcb's that the length of the board makes a difference on the impedance of the line. In those case typically you can expect an ohm or two of impedance when checking the whole trace.
 

MrChips

Joined Oct 2, 2009
23,054
I am going to assume that there is a simple explanation.

The manufacturer has automated resistor manufacturing facility. The operator dials in the specifications for the day's production run. Yesterday they manufactured 10 million 1/16W 100mΩ ±1% 0805 SMD resistors. For the purpose of inventory control and parts identification this is the information that is recorded. A number of random units are sampled and tested for quality control and assurance.

Today they are manufacturing 10 million 1/16W 0Ω ±1% 0805 SMD resistors.

That's all folks!
 
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