Inductor and Capacitor 3-digit exponent value codes: is there a standard?

Question

I've seen the standard NNX exponential value code where NN are the significant digits and X is the \$10^X\$ exponent such that \$value = N\cdot 10^X\$. For example, 121 means 120 (in some unit).

I've also seen component models like the Coilcraft model 0402CS-1N8 where here N is to be interpreted as a decimal point giving the value 1.8nH...and Murata uses R for decimal point in their capacitors. For example:

• 9R1 means 1.9 pF: GJM1555C1H9R1WB01
• R10 means 0.10 pF: GQM1555C2DR10BB01

so I assumed that, as an industry standard, all alpha-digits in the value code are decimal points.

But then, the world was turned upside in my component parser when I found that Coilcraft has a 0402CS-R10 part where "R10" means 100nH (!) and thus R means "multiply times 10"---which is clearly different from Murata's use of "R" as a decimal point.

I know, manufacturers can do whatever they want with model numbers, they own the naming space---but:

Is there a standard specification for component value naming for RF components like inductors, caps, and RF resistors. If so, can you provide a reference?

Other manufacturer naming conventions:

Caps:

• AVX: uses "R" for decimal point in pF
• ATC: uses "R" for decimal point in pF
• Murata: uses "R" for decimal point in pF
• Vishay: uses "R" for decimal point in pF

Inductors:

• AVX: uses "N" for decimal point in nH
• Murata: uses "N" for decimal point in nH
• Coilcraft:
  • uses "N" for decimal point in nH
  • uses "R" for decimal point in uH
• Vishay:
  • uses "N" for decimal point in nH
  • uses "R" for decimal point in uH

... so maybe there is a pattern here with R in uH.

Resistors

• Vishay and others use "R" for decimal point unless it is in mΩ, in which case they use "L", as in 0L50 meaning 0.5mΩ. Also si units are used, such as 1K0 or 1M0 for 1KΩ or 1MΩ.
• Here is a good reference for resistor naming:
  • Methods for Coding Resistor Values in Part Numbers
  • is there a similar reference for caps and inductors?

Would be nice if there is an official reference somewhere that can be relied upon that defines component value codes.

Answer 1

I think there is at least a common sense for the base unit of a component. For capacitors it is pF, so 102 = 100 pF, 224 = 220 nF, 106 = 10 uF. If the component value needs digits below the base unit, a decimal point is needed but can be overlooked. So "R" is a common, good readable substitute and R10 as a capcitor is 0.1 pF.

For inductors the base unit is µH, e.g. 471 = 470 µH, 683 = 68 mH and R10 = 100 nH in this system.