# MF52 Series Bead-Type Precision NTC Temperature Sensors

> Leaded bead NTC thermistors for precision temperature measurement; R25 10–100 kΩ, B25/50 3,380 or 3,950 K, thermal time constant ≤7 s in static air.

- Series code: MF52
- Product line: [Thermistors (NTC / PTC)](https://www.songtian-ste.com/en/products/thermistors/) › NTC thermistors for temperature sensing and compensation
- Part numbers: Part-number list on request
- Page: https://www.songtian-ste.com/en/products/ntc-thermistors/mf52/
- Chinese version: https://www.songtian-ste.com/zh/products/ntc-thermistors/mf52/
- [Ask AI about this series](https://www.songtian-ste.com/en/products/ntc-thermistors/mf52/?ask=Help%20me%20choose%20a%20part%20from%20the%20STE%20MF52%20series.)

## Key specifications

| Parameter | Value |
| --- | --- |
| R25 | 10 / 50 / 100 kΩ |
| B25/50 | 3,380 K / 3,950 K |
| R25 tolerance | ±1% to ±10% |
| Thermal time constant, static air | ≤7 s |
| Dissipation constant, static air | ≥2.0 mW/°C |
| Operating temperature | −40 °C to +125 °C |

## Engineering details

### Overview

Leaded bead NTC thermistors for precision temperature measurement. Two constructions: 52A (A10) with tinned copper or tinned copper-clad steel leads, and 52B (B10) with enamelled wire. R25 10, 50 or 100 kΩ, B25/50 3,380 K or 3,950 K; thermal time constant ≤7 s in static air. Operating temperature −40 °C to +125 °C.

#### Series features

- Two bead constructions: tinned bare leads (52A) or enamelled wire (52B)
- R25 10, 50 and 100 kΩ with B25/50 3,380 K or 3,950 K; B25/85 values specified
- R25 tolerance ±1% to ±10%; B-value tolerance ±1% or ±2%
- Thermal time constant ≤7 s and dissipation constant ≥2.0 mW/°C in static air
- Operating temperature −40 °C to +125 °C; bulk packing

#### Typical applications

- Air-conditioning and heating equipment
- Liquid-level and liquid-temperature sensing, after immersion and coating validation
- Electronic thermometers and precision instruments
- Mobile-phone and battery-pack temperature sensing
- Appliance and control electronics that need a compact bead and a choice of lead construction

### Specifications

|   |   |
| --- | --- |
| Function | Leaded NTC bead thermistor for temperature measurement; zero-power resistance decreases as the element temperature rises |
| Constructions | Precision bead NTC in two constructions: 52A (A10) and 52B (B10) |
| R25 values | 10 kΩ · 50 kΩ · 100 kΩ |
| R25 tolerance | ±1% · ±2% · ±3% · ±5% · ±10% |
| R25 10 kΩ, B 3,380 K | B25/50 3,380 K · B25/85 3,435 K |
| R25 10 kΩ, B 3,950 K | B25/50 3,950 K · B25/85 4,000 K |
| R25 50 kΩ | B25/50 3,950 K · B25/85 4,000 K |
| R25 100 kΩ | B25/50 3,950 K · B25/85 4,000 K |
| B-value tolerance | ±1% · ±2% |
| B-value definition | B = ln(R1/R2) / (1/T1 − 1/T2) |
| B-value reference temperatures | B25/50: T1 = 298.15 K, T2 = 323.15 K · B25/85: T1 = 298.15 K, T2 = 358.15 K |
| Temperature accuracy | R25 and B tolerances do not state a ±°C accuracy. Calculate the temperature error from the R/T table. |
| Zero-power resistance | DC resistance at temperature t, measured at a power low enough that any further reduction changes the resistance by less than 0.1% |
| Operating temperature | −40 °C to +125 °C |
| Thermal time constant | ≤7 s in static air |
| Thermal time constant, definition | Time to reach 63.2% of the change from initial to final temperature, under zero-power conditions |
| Dissipation constant | ≥2.0 mW/°C in static air |
| Leads, 52A (A10) | Tinned copper wire or tinned copper-clad steel wire |
| Body, 52A (A10) | D max. 2.2 mm · L1 max. 3.5 mm |
| Lead dimensions, 52A (A10) | L2 ≥25.0 mm · d 0.35 ±0.05 mm · F 1.8 ±0.5 mm |
| Leads, 52B (B10) | Enamelled wire; conductor alloy and enamel thermal class on request |
| Body, 52B (B10) | D max. 2.0 mm · L1 max. 6.0 mm |
| Lead dimensions, 52B (B10) | L2 to customer specification · L3 3.0 ±1.0 mm · d 0.28 ±0.05 mm |
| Terminal option | 0 = without terminal · P = with terminal; terminal type and drawing on request |
| Lead length | Coded in the last four characters of the part number; 52A: L2 min. 25 mm; 52B: length to customer specification |
| Hand soldering and rework | 300 °C max. · 3 s max. · solder point at least 2 mm from the coating |
| Packing | Bulk |
| Storage | ≤35 °C · ≤70% RH · 12 months · keep the original package closed and reseal after opening; avoid corrosive atmospheres that degrade solderability |
| Environmental compliance | RoHS and REACH compliant; halogen status and material declarations on request |
| Liquid use | Validate immersion, fluid compatibility and insulation before use in liquids. |
| Automotive use | No AEC-Q200 qualification is specified for this series |
| Further data on request | R/T table · rated power, max. sensing current and voltage, allowed self-heating and derating versus ambient temperature · insulation resistance, dielectric withstand and body-to-lead isolation · coating material, flammability and moisture-barrier data · wave or reflow soldering, enamel stripping, lead forming, cleaning and potting compatibility · immersion and fluid-compatibility data · endurance, thermal-cycling, humidity, high- and low-temperature storage, vibration, shock, lead-strength and solderability results |

### Variants

Ranges by dielectric, package and lead style within this series.

| Variant | Body dimensions | R25 / B25/50 | Thermal time constant / dissipation constant / temperature range | Lead / land pattern | Notes |
| --- | --- | --- | --- | --- | --- |
| 52A (A10) | D max. 2.2 mm · L1 max. 3.5 mm | 10 kΩ / 3,380 K · 10, 50, 100 kΩ / 3,950 K | τ ≤7 s · δ ≥2.0 mW/°C · −40 °C to +125 °C | L2 ≥25 mm · d 0.35 ±0.05 mm · F 1.8 ±0.5 mm · tinned copper or copper-clad steel | Compact bare-lead bead for PCB or assembly integration. Validate lead heat flow, coating and accuracy. |
| 52B (B10) | D max. 2.0 mm · L1 max. 6.0 mm | 10 kΩ / 3,380 K · 10, 50, 100 kΩ / 3,950 K | τ ≤7 s · δ ≥2.0 mW/°C · −40 °C to +125 °C | L2 to customer specification · L3 3 ±1 mm · d 0.28 ±0.05 mm · enamelled wire | Enamelled-wire construction for custom lead length. Validate enamel class, termination and strain relief. |

### Selection guide

Start with the temperature and error window. Then choose one of the four R25/B combinations and the A or B lead construction, and verify self-heating, thermal response, coating and fluid compatibility, process and qualification for the selected part number.

1. **Define temperature, accuracy and environment**
   Set the mission profile within −40 °C to +125 °C, the required ±°C accuracy, response, drift, calibration, airflow or liquid exposure, mechanical load and application qualification.
2. **Select R25 and B value**
   Select 10 kΩ / 3,380 K or 10, 50 or 100 kΩ / 3,950 K for the circuit resolution. R/T table and tolerance band on request.
3. **Select construction 52A or 52B**
   Use 52A for tinned bare leads and a body length of max. 3.5 mm, or 52B for enamelled wire and customer-specified length. Validate lead heat flow, insulation, termination and mechanical integration.
4. **Control excitation and thermal response**
   Calculate max. voltage, current, power and self-heating across the curve. Correlate the ≤7 s static-air value with the actual PCB, potting, fluid, contact or enclosure thermal path.
5. **Specify process and qualification**
   Specify coating and lead materials, body and lead drawing, terminal and length, soldering or enamel process, packing, environmental declarations, drift and application-specific reliability for the selected part number.

### Design notes

#### Use one of the four R25/B combinations

MF52 is specified at 10 kΩ / 3,380 K and at 10, 50 and 100 kΩ / 3,950 K. Other values on request.

#### R25 and B tolerance are not ±°C accuracy

Build the temperature error budget from R/T tolerance, ADC, reference and divider error, self-heating, thermal gradients, calibration and drift at every critical temperature.

#### Choose the lead construction as part of the thermal design

Copper, copper-clad steel and enamelled wire differ in heat conduction, insulation and termination. Validate the complete lead path; do not assume identical response or object-temperature tracking.

#### Validate any liquid or potting exposure

Before use in liquids, validate coating, insulation under bias, potting cure, moisture ingress and response in the actual medium.

#### Protect the bead and lead exit

Avoid bending, clamping or pulling at the coated body. Use controlled lead forming, board support, strain relief and solder or enamel termination so that assembly stress does not alter resistance or crack the coating.

#### Qualify automotive and battery use

Battery and automotive applications need mission-profile temperature, electrical isolation, flame and fault behavior, vibration, humidity, change control and application-specific qualification.

### Part numbering

Example ordering code. Not every combination is available.

`MT · 52A · 103 · F · 3950 · F · 0 · 0000`

| Code | Meaning |
| --- | --- |
| MT | Temperature-sensing NTC prefix |
| 52A | Construction: 52A (A10) or 52B (B10) |
| 103 | R25: 103 = 10 kΩ, 104 = 100 kΩ; available 10, 50 and 100 kΩ |
| F | R25 tolerance: F = ±1%; G ±2%, H ±3%, J ±5%, K ±10% |
| 3950 | Nominal B25/50: 3950 = 3,950 K; 3380 = 3,380 K (B25/85 4,000 K and 3,435 K) |
| F | B-value tolerance: F = ±1%; G = ±2% |
| 0 | Terminal: 0 = without terminal; P = with terminal |
| 0000 | Lead length: 52A min. 25 mm, 52B to customer specification; code table on request |

## Datasheets & approval documents

- [Technical document: MF52 series epoxy-coated NTC thermistors](https://www.songtian-ste.com/documents/source-cn/%E8%B4%9F%E6%B8%A9%E5%BA%A6%E7%B3%BB%E6%95%B0%E7%83%AD%E6%95%8F%E7%94%B5%E9%98%BB%E5%99%A8-MF52%E7%B3%BB%E5%88%97.pdf) — PDF · Chinese · 320 KB

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