Zero Ohm Resistor (ZOR)

 Zero Ohm Resistor (ZOR) is simply a zero-ohm (0Ω) jumper!

It is a single resistor that is manufactured to have zero ohm of resistance when measured. A through-hole resistor with zero ohm is often marked with a single black band, which indicates the value of the resistance whereas a surface mount ceramic resistor will have a single or a multiple number of zeros to represent the zero ohm resistance.

A few reasons to use a zero-ohm resistor:

• It simplifies PCB routing and traces
• It helps to easily enable or disable a signal
• It isolates inputs or outputs between different circuit sections during development, servicing, or repairing circuits (just by unsoldering them)

Basically, a zero ohm resistor functions like a wire. Since most large batches of printed circuit boards are automatically populated by machines, the machines can easily place these standardized resistors when a jumper is needed instead of cutting and stripping a custom wire or jumper wire resistor.

There is also a less obvious rationale for zero-ohm resistors. It can complicate and conceal a circuit’s function and confuse someone trying to trace out and thus reverse-engineer the design.

These are at least some reasons where this apparently mystic component makes sense.

Note that the resistance of a zero ohm resistor is only approximately zero, that is, only a maximum is specified, which is typically in the range of 10–50 mΩ.

Here is the datasheet of a zero ohm chip resistor in PDF  https://www.resistor.com/assets/pdf/RCZ1206CPX.pdf

So, zero-ohm resistor is an odd component whose function seems useless at first. However, it is quite useful for masters who are aware of it and empathize how it can help solve circuit design and layout problems at very low cost with no or minimal complexities.

Thanks for reading!