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What is a resistor?: Regarding chip resistor sizes

Chip Resistor Specifications

Chip Resistor Sizes

The external dimensions of chip resistors are typically designated using company-specific notation and are indicated in both mm and inches.

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ROHM Part No. Chip Size
(Length x Width)
mm inch
***004 0.4 mm × 0.2 mm 0402 01005
***006 0.6 mm × 0.3 mm 0603 0201
***01 1.0 mm × 0.5 mm 1005 0402
***03 1.6 mm × 0.8 mm 1608 0603
***10 2.0 mm × 1.2 mm 2012 0805
***18 3.2 mm × 1.6 mm 3216 1206
***25 3.2 mm × 2.5 mm 3225 1210
***50 5.0 mm × 2.5 mm 5025 2010
***100 6.4 mm × 3.2 mm 6432 2512

***Represents part numbers (excluding chip networks)

What is 'Rated Power'?

The rated power is maximum power that can be used under continuous operation at a specified ambient temperature. When current is supplied to a chip resistor heat is generated. Since the upper limit of the operating temperature of a chip resistor has been determined, it is necessary to reduce the power in accordance with the derating curve for temperatures above Ta=70°C.

Power Derating Curves

What is 'Temperature Coefficient of Resistance'?

In any material, the resistance of that material will change as the temperature changes. This extends to resistors as well. The rate of resistance change based on temperature is referred to as the Temperature Coefficient of Resistance. It is indicated in units of ppm/C and determined from the resistance change from the reference temperature and the change in temperature.

Temperature Coefficient of Resistance (ppm/℃) = (R-Ra)/Ra ÷ (T-Ta)×1000000 Ex: What is the resistance change rate for a chip resistor with a TCR of 100ppm/℃ and a change in temperature from 20℃ to 100℃? Resistance Change Rate Based On Temperature (Example)