Temperature sensing on a crowded board usually means putting the thermistor wherever there is room, not where the heat is. Murata has announced the NCU01 series, an NTC thermistor in the 008004-inch size (0.25 mm × 0.125 mm, called 0201M in metric), which the company says is the world's smallest based on its own research as of 19 October 2026. Compared with its previous smallest 01005-inch part (0.4 mm × 0.2 mm), it needs about 60% less mounting area, and it keeps the same ±1% resistance tolerance and ±1% B-constant tolerance.
Why the size matters
An NTC thermistor reports its own temperature, not the temperature of the chip you care about. Put it a few millimetres away from a PMIC, charger IC or SoC and the reading can sit below the real hot-spot temperature, and fast changes show up late. Murata's pitch is simply that a smaller part can be placed closer, on phone and wearable boards and even inside IC packages and system-in-package (SiP) modules, where a 01005 part may not fit at all.
The maths checks out: 0.25 × 0.125 mm is 0.031 mm², against 0.08 mm² for the 01005, a cut of roughly 61%.
What the tolerances mean
Two key numbers define how closely one NTC matches the next. Resistance tolerance (±1%) is the spread of resistance at the reference temperature, and B-constant tolerance (±1%) is the spread of the slope of the resistance-versus-temperature curve. Neither is a ±1 °C system accuracy. As a rough guide, for a typical NTC with a B value of 3,400 K to 4,300 K, a 1% resistance error works out to about 0.2 °C to 0.26 °C at 25 °C. Your divider resistor, ADC and self-heating from the sense current add to that, so keep the bias current low.
Availability
The first values are 10 kΩ and 100 kΩ, with more to follow. Murata plans to start sample shipments in October 2026 and mass production during 2027. There is no public datasheet with B values or dissipation constants yet, and no pricing.
Don't expect to hand-solder one. A 008004 part is meant for high-density pick-and-place lines building phones, wearables and SiP modules. For hobby boards, 0402 and 0603 NTCs remain the practical choice.
Image credit: Murata Manufacturing (product photo); to-scale size chart by CircuitDigest.
Add a comment
No account needed. Your comment appears once a moderator has reviewed it.