IN Brief:
- The NCU01 uses an 008004-inch package measuring 0.25 × 0.125 mm, compared with the previous 01005-inch device.
- Murata specifies ±1% resistance and B-constant tolerances and initially plans 100 kΩ and 10 kΩ nominal resistance options.
- Sampling is planned for October 2026, with mass production scheduled during 2027; closer sensor positioning is an application benefit, not a measured system accuracy guarantee.
Murata Manufacturing has developed an 008004-inch negative temperature coefficient thermistor measuring 0.25 × 0.125 mm, reducing the mounting area required for its temperature sensors. The NCU01 series is aimed at densely assembled electronics where the distance between the sensor and a heat-generating component can affect the usefulness of a temperature measurement.
The new device occupies approximately 60% less mounting area than Murata’s previous smallest thermistor, a 01005-inch component measuring 0.4 × 0.2 mm. The company states that its new ceramic construction and manufacturing process preserve resistance and B-constant tolerances of ±1%, despite the reduction in dimensions.
An NTC thermistor changes electrical resistance as its temperature changes, with resistance falling as temperature rises. Measurement circuitry can use that relationship to estimate the temperature at the sensing element. The estimate depends on the selected component characteristics, the measurement circuit, and how accurately the device follows the temperature of the object being monitored.
Sensor position becomes critical when electronic equipment contains several local heat sources. A thermistor located away from a processor, power device, or other component may be separated by material with appreciable thermal resistance. Its temperature can then differ from the component temperature, particularly during short operating peaks.
A smaller thermistor provides more flexibility when the surrounding circuit layout contains fine-pitch packages, densely routed conductors, and nearby passive components. It can be positioned closer to the heat source where the available clearance permits, reducing part of the thermal path between the monitored device and the sensor.
Closer placement can also reduce the time taken for the sensor to respond to a change in local temperature, although Murata has not reported a measured system response-time improvement for every possible installation. Thermal coupling, mounting geometry, and the mass of adjacent materials still determine how quickly a temperature change reaches the sensing element.
The difference in physical area is substantial at this scale. The previous 0.4 × 0.2 mm outline covers 0.08 square millimetres, while the new 0.25 × 0.125 mm body covers 0.03125 square millimetres. Those figures describe component dimensions; the final board area also includes the land pattern and the clearances required for reliable assembly.
Reducing component size introduces its own manufacturing demands. Small variations in the ceramic composition, electrode arrangement, or sintering conditions can influence resistance and temperature response. Murata attributes the NCU01 development to changes in ceramic materials, precision processing, and the component structure needed to maintain consistent characteristics.
The resistance tolerance concerns variation from the specified nominal resistance under defined conditions. The B-constant describes the temperature dependence of resistance over a specified interval, so its tolerance affects the relationship used to convert measured resistance into temperature. Neither tolerance independently establishes an overall temperature measurement accuracy of ±1%.
Practical accuracy also depends on the resistor or converter used to measure the thermistor, calibration, electrical noise, and the temperature gradient between the sensor and the intended measurement point. Heating produced by measurement current can introduce a further error, especially where thermal mass is low and the sensing current is not appropriately limited.
Murata intends to introduce 100 kΩ and 10 kΩ nominal resistance options first, with additional values to follow. The appropriate resistance depends on the sensing circuit, its supply voltage, expected temperature range, and the measurement current that can be used without unacceptable self-heating.
Initial applications include circuit board monitoring in smartphones and wearable devices, but the company also identifies integrated circuit packages and system-in-package modules. These assemblies offer little spare space around processors and other active elements, so a sensor with a smaller footprint can broaden possible mounting positions without changing the entire package layout.
The stated dimensions are also relevant to manufacturing. Component placement equipment, solder paste printing, inspection, and rework procedures must be suitable for an 008004-inch device. A reduction in component footprint is therefore not by itself sufficient to establish manufacturability on an existing production line.
Murata describes the NCU01 as the world’s smallest NTC thermistor according to its assessment on 20 October 2026, a manufacturer claim rather than an independently established ranking. Samples are planned to begin shipping during October 2026 and mass production during 2027, giving equipment developers an opportunity to assess thermal behaviour and assembly compatibility before larger-scale supply.
The company has not provided completed production volumes or device-level temperature accuracy results. The confirmed advance is a smaller ceramic sensing component with the stated electrical tolerances, while the effect on thermal monitoring will be determined by where and how it is incorporated in a finished assembly.
