What does the B value mean in a thermistor?

The B value (or Beta value) is a material constant that describes the sensitivity of an NTC thermistor over a temperature range, expressed in Kelvin (K). A higher B value indicates greater sensitivity. The B value is used to calculate resistance at any temperature using the Steinhart-Hart equation.

What resistance value should I choose for my NTC thermistor?

The most common values are 10K ohm (at 25°C), which is widely used in TEC controllers, laser systems, and general temperature sensing. 100K ohm thermistors are preferred for wider temperature ranges and lower self-heating. 5K and 50K options offer alternatives depending on your circuit impedance requirements. For TEC controller applications, 10K is the standard recommendation.

What is the temperature range of Analog Technologies NTC thermistors?

Our glass-encapsulated NTC thermistors cover a wide operating range. Most models operate from -40°C to +250°C, with select models covering -55°C to +250°C and high-temperature versions rated up to +300°C.

Can I get custom thermistor assemblies?

Yes. Analog Technologies offers fully customized thermistor assemblies including custom wire lengths, custom connector types, custom housing materials, and custom resistance values. Contact sales@analogti.com to discuss your requirements.

Company's Patents

Contact Us

Analog Technologies, Inc.
1161 Ringwood Ct., #110
San Jose, CA 95131
U.S.A.

Tel.: 408-748-9100

Online Store:
www.smtzone.com
shop.analogtechnologies.com

Help us improve our webpage:
email

Home > Products > Thermistors

NTC Thermistors and Thermistor Assemblies

Q: What is the difference between NTC and PTC thermistors?

NTC (Negative Temperature Coefficient) thermistors decrease in resistance as temperature rises, making them ideal for temperature sensing and measurement. PTC (Positive Temperature Coefficient) thermistors increase in resistance with temperature, typically used for overcurrent protection. NTC thermistors offer higher sensitivity and are the preferred choice for precision temperature measurement applications.

Q: Why choose glass encapsulated thermistors over epoxy encapsulated?

Glass encapsulated thermistors offer nearly zero long-term drift compared to epoxy types which can exhibit higher drift over years of use. They also support a wider temperature range (up to 300°C), smaller bead sizes (from 0.8mm diameter), and faster thermal response times.

NTC Thermistor Selection Guide

Compare every part side-by-side · Sortable specs · Live stock · One-click buy

NTC (Negative Temperature Coefficient) Thermistors are high-sensitivity temperature sensors widely used in industrial, medical, and consumer applications. Compared to RTDs, thermocouples, and temperature ICs, NTC thermistors deliver superior sensitivity, low noise, and minimal peripheral circuitry at very low cost — making them the preferred choice for precision temperature sensing in compact systems.

Most of our thermistors use glass encapsulation, which provides near-zero long-term drift, a wider operating temperature range (up to 300°C), and smaller bead sizes versus conventional epoxy encapsulated types. The lineup also includes one epoxy-encapsulated option (ATH10K1R0) as a cost-effective alternative. These properties make them ideal for use with our TEC controllers and TEC modules to build high-stability, low-drift temperature regulation systems.

±0.05°C

Precision @ 25°C

0.55mm

Min. Bead Diameter

-55°C ~ +300°C

Operating Temp. Range

~$0.8

From @ 500pcs

≈0 Drift

Glass Encapsulation

Glass-encapsulated thermistors are available in two lead styles: axial (leads from opposite ends) and radial (leads from the same side). We also offer lug-mount versions with a metal ring for easy attachment to thermal conductive surfaces. Bare radial beads (Φ0.8–1.3mm) are commonly used for sensing laser diode chip temperatures; axial styles suit battery packs and consumer electronics.

For assistance selecting the right thermistor or assembly, please contact us — we're happy to help with custom requirements.

How it works — See our videos
RoHS Certificate of Compliance for Thermistors
REACH Certificate of Compliance for Thermistors

NTC Thermistor vs. RTD vs. Thermocouple: Which to Choose?

Parameter	NTC Thermistor	RTD (PT100/PT1000)	Thermocouple
Sensitivity	★★★★★ Very High	★★★ Moderate	★★ Low
Accuracy	±0.05°C (precision)	±0.1°C typical	±1–2°C typical
Temperature Range	-55°C to +300°C	-200°C to +850°C	-200°C to +1700°C
Response Time	Fast (small bead: <1s)	Moderate	Moderate to Slow
Cost	★★★★★ Very Low	★★★ Moderate	★★★ Moderate
Linearity	Non-linear (needs correction)	Near-linear	Non-linear
Best For	TEC control, laser diodes, medical, battery, precision sensing	Industrial process control	High-temperature industrial

Typical Applications by Industry

Industry / Application	Recommended Thermistor Type	Key Requirement
Laser Diode Temperature Control	10K, Φ0.8mm bare bead (e.g., ATH10KR8B)	Small size, fast response, used with TEC controllers
Medical Devices	Precision ±0.05°C models, glass encapsulated	Long-term stability, near-zero drift
Battery Pack / BMS	10K axial with leads (e.g., ATH10K1R25)	Wide temp range, cost-effective
Industrial HVAC	Thermistor assemblies with metal housing	Durability, moisture resistance
Optical / Photonics	Φ0.8mm–1.3mm bare bead, high B-value	Miniature size, non-intrusive mounting
Consumer Electronics	Epoxy or glass radial lead thermistors	Low cost, high volume availability

Glass & Epoxy Encapsulated NTC Thermistors

ATI's glass-encapsulated NTC thermistor beads are the workhorse for precision temperature sensing in laser-diode modules, TEC controllers, medical instruments, and battery management systems. The series spans 5 kΩ to 230 kΩ nominal resistance at 25 °C with industry-standard B-values of 3404 K, 3478 K, 3950 K, 4066 K, and 4177 K, in both radial (leads from the same end) and axial (leads from opposite ends) configurations. Bead diameters from Φ0.55 mm to Φ1.8 mm let designers pick the smallest fit for a butterfly laser package, TO-can mount, battery hotspot, or general PCB through-hole sensing. Compared with conventional epoxy-encapsulated parts, glass encapsulation delivers near-zero long-term drift (typically <0.1 °C/year), a wider operating range up to +300 °C, and faster thermal response (~1 s for the small beads). Each base part is also offered with optional PFA insulating tubing (T63 / T65 / T70) and a moisture-sealed variant (T63S / T65S / T70S) for medical, automotive, and sterilization-rated applications. ATH10K1R0 is the one epoxy-encapsulated option in this group — a cost-effective Φ1.0 mm alternative for general-purpose home-appliance and consumer sensing where ultra-low drift is not required. All parts are 100% Pb-free, RoHS & REACH compliant.

Termination suffixes: base bare leads | T63 / T65 / T70 with PFA insulating tubing, non-sealed | T63S / T65S / T70S with PFA tubing, sealed at bead (moisture-proof). Variants share specs & datasheet — they're grouped into one row each.

Part Number (+ Variants)	Nominal R @ 25°C	Bead Φ (mm)	Operating Temp Range	Dissip. Factor	B Value @ 25 / 50°C	Data- sheet	In Stock	Buy Now
Φ0.55 mm — Radial Leaded (Glass Encapsulated)
ATH10KR55B3950K Bare leads	10K ± 1%	0.55 ± 0.2mm	−30°C to +300°C	0.25 mW/°C	3950K ± 1%		0
Φ0.8 mm — Radial Leaded (Glass Encapsulated)
ATH5KR8B3950K Bare leads	5K ± 1%	0.8 ± 0.15mm	−40°C to +250°C	1.2 mW/°C	3950K ± 1%		0
ATH10KR8B Bare leads ATH10KR8BT65 + T65 tubing ATH10KR8BT65S + T65S sealed	10K ± 1%	0.8 ± 0.1mm	−55°C to +250°C	0.4 mW/K	3478K / 3492K *		0 120 129
ATH10KR8B3404K Bare leads ATH10KR8B3404KT65 + T65 tubing ATH10KR8B3404KT65S + T65S sealed	10K ± 1%	0.8 ± 0.15mm	−40°C to +200°C	1.2 mW/°C	3404K ± 1%		0 0 0
ATH10KR8B3950K0.5% Bare leads	10K ± 0.5%	0.8 ± 0.15mm	−40°C to +250°C	1.2 mW/°C	3950K ± 1%		0
ATH50KR8B3950K Bare leads	50K ± 1%	0.8 ± 0.1mm	−40°C to +300°C	0.6 mW/°C	3950K ± 1%		0
ATH50KR8B3950K0.5% Bare leads	50K ± 0.5%	0.8 ± 0.1mm	−40°C to +300°C	0.6 mW/°C	3950K ± 1%		360
ATH100KR8 Bare leads ATH100KR8T63 + T63 tubing ATH100KR8T63S + T63S sealed	100K ± 1%	0.8 ± 0.1mm	−55°C to +250°C	0.4 mW/K	4066K ± 1%		127 14 0
ATH100KR8B3950K Bare leads	100K ± 1%	0.8 ± 0.2mm	−40°C to +300°C	0.6 mW/°C	3950K ± 1%		0
ATH100KR8B3950K0.5% Bare leads	100K ± 0.5%	0.8 ± 0.2mm	−40°C to +300°C	0.6 mW/°C	3950K ± 1%		400
ATH230KR8B4177K Bare leads	230K ± 1%	0.8 ± 0.2mm	−40°C to +300°C	0.6 mW/°C	4177K ± 1%		0
Φ1.0 mm — Radial Leaded (Epoxy Encapsulated)
ATH10K1R0 Epoxy encapsulated	10K ± 1%	1.0 ± 0.1mm	−55°C to +250°C	0.5 mW/K	3478K ± 1%		1825
Φ1.25 mm — Radial Leaded (Glass Encapsulated)
ATH10K1R25 Bare leads ATH10K1R25T70 + T70 tubing ATH10K1R25T70S + T70S sealed	10K ± 1%	1.25 ± 0.03mm	−40°C to +270°C	1.0 mW/°C	3990K ± 1%		55 100 203
ATH100K1R25 Bare leads ATH100K1R25T70 + T70 tubing ATH100K1R25T70S + T70S sealed	100K ± 1%	1.25 ± 0.2mm	−40°C to +270°C	0.9 mW/°C	3990K ± 1%		945 0 10
Φ1.3 mm — Radial Leaded (Glass Encapsulated)
ATH5K1R3B3950K Bare leads ATH5K1R3B3950KT65 + T65 tubing ATH5K1R3B3950KT65S + T65S sealed	5K ± 1%	1.3 ± 0.2mm	−40°C to +250°C	0.9 mW/°C	3950K ± 1%		0 0 0
ATH10K1R3B3950K Bare leads ATH10K1R3B3950KT65 + T65 tubing ATH10K1R3B3950KT65S + T65S sealed	10K ± 1%	1.3 ± 0.2mm	−40°C to +250°C	0.9 mW/°C	3950K ± 1%		0 0 0
ATH10K1R3B3950K0.5% Bare leads ATH10K1R3B3950K0.5%T65 + T65 tubing ATH10K1R3B3950K0.5%T65S + T65S sealed	10K ± 0.5%	1.3 ± 0.2mm	−40°C to +250°C	0.9 mW/°C	3950K ± 1%		0 0 0
ATH20K1R3B3950K Bare leads	20K ± 1%	1.3 ± 0.2mm	−40°C to +250°C	1.4 mW/°C	3950K ± 1%		0
ATH30K1R3B3950K Bare leads	30K ± 1%	1.3 ± 0.2mm	−40°C to +250°C	1.4 mW/°C	3950K ± 1%		805
ATH50K1R3B3950K0.5% Bare leads	50K ± 0.5%	1.3 ± 0.2mm	−55°C to +250°C	0.9 mW/°C	3950K ± 1%		0
ATH100K1R3B3950K Bare leads	100K ± 1%	1.3 ± 0.2mm	−40°C to +300°C	0.4 mW/°C	3950K ± 1%		0
ATH100K1R3B3950K0.5% Bare leads	100K ± 0.5%	1.3 ± 0.2mm	−40°C to +250°C	0.9 mW/°C	3950K ± 1%		0
Φ1.8 mm — Axial Leaded (Glass Encapsulated)
ATH5K1R8B3950K Axial leads	5K ± 1%	1.8 ± 0.2mm	−55°C to +250°C	2 mW/°C	3950K ± 1%		150
ATH10K1R8B3950K Axial leads	10K ± 1%	1.8 ± 0.2mm	−55°C to +250°C	2 mW/°C	3950K ± 1%		200
ATH20K1R8B3950K Axial leads	20K ± 1%	1.8 ± 0.2mm	−55°C to +250°C	2 mW/°C	3950K ± 1%		200
ATH30K1R8B3950K Axial leads	30K ± 1%	1.8 ± 0.2mm	−55°C to +250°C	2 mW/°C	3950K ± 1%		200
ATH50K1R8B3950K Axial leads	50K ± 1%	1.8 ± 0.2mm	−55°C to +250°C	2 mW/°C	3950K ± 1%		200
ATH100K1R8B3950K Axial leads	100K ± 1%	1.8 ± 0.2mm	−55°C to +250°C	2 mW/°C	3950K ± 1%		200

Note: Maximum Power @ 25°C ratings (typically 18–50 mW) and detailed thermal data are listed in each part's datasheet (PDF icon above).

Thermistor Assemblies

Ring Lug Assemblies — Bolt-On Mounting (10K & 100K)

ATI's ring-lug NTC thermistor assemblies mount directly to a heat sink, laser-diode submount, motor housing, or busbar with an M2 or M3 screw — no thermal-paste step, no drilling required. A glass-encapsulated thermistor bead is permanently attached to a copper or brass lug ring, combining the near-zero drift of glass encapsulation with rugged bolt-on mounting. Two thermal-curve families are stocked: the 10 kΩ group (ATH10KB3404KL2A, ATH10KBL2A, ATH10KL2B, ATH10KL2C, ATH10KL2D) and the 100 kΩ group (ATH100KL2A, ATH100KL2B, ATH100KL2C). Ring-hole sizes range from 2.18 mm (M2) to 3.02 mm (M3); B-values cover 3404 K, 3492 K, 3950 K, and 4066 K to match popular TEC-controller R/T curves out of the box. Each base part is also available in +T65 / +T70 (PFA insulating tubing, non-sealed) and +T65S / +T70S (sealed at bead, moisture-proof) variants. Typical applications: laser-diode TEC temperature control, fiber-optic transceiver cooling, optical-component temperature monitoring, EV battery-pack thermal management, motor stator hotspot detection, and precision heat-sink temperature sensing.

Part Number (+ Variants)	Nominal R @ 25°C	Lead Φ & Ring Size	Operating Temp Range	B Value @ 25 / 50°C	Data- sheet	In Stock	Buy Now
10K Ring Lug Assemblies — Bolt-On Mounting
ATH10KB3404KL2A Bare leads ATH10KB3404KL2AT65 + T65 tubing ATH10KB3404KL2AT65S + T65S sealed	10K ± 1%	lead 0.15mm	−40°C to +200°C	3404K ± 1%		22 52 15
ATH10KBL2A Bare leads ATH10KBL2AT65 + T65 tubing ATH10KBL2AT65S + T65S sealed	10K ± 1%	lead 0.15mm	−55°C to +250°C	3492K ± 1%		109 88 266
ATH10KL2B Bare leads ATH10KL2BT70 + T70 tubing ATH10KL2BT70S + T70S sealed	10K ± 1%	lead 0.2mm; ring 2.18mm	−40°C to +270°C	3950K ± 1%		37 37 18
ATH10KL2C Bare leads ATH10KL2CT70 + T70 tubing ATH10KL2CT70S + T70S sealed	10K ± 1%	lead 0.2mm; ring 3.02mm	−40°C to +270°C	3950K ± 1%		1 44 100
ATH10KL2D Bare leads ATH10KL2DT70 + T70 tubing ATH10KL2DT70S + T70S sealed	10K ± 1%	lead 0.2mm	−40°C to +270°C	3950K ± 1%		0 0 0
100K Ring Lug Assemblies — Bolt-On Mounting
ATH100KL2A Bare leads ATH100KL2AT63 + T63 tubing ATH100KL2AT63S + T63S sealed	100K ± 1%	lead 0.15mm	−55°C to +250°C	4066K ± 1%		21 21 9
ATH100KL2B Bare leads ATH100KL2BT70 + T70 tubing ATH100KL2BT70S + T70S sealed	100K ± 1%	lead 0.2mm; ring 2.18mm	−40°C to +270°C	3950K ± 1%		23 23 23
ATH100KL2C Bare leads ATH100KL2CT70 + T70 tubing ATH100KL2CT70S + T70S sealed	100K ± 1%	lead 0.2mm; ring 3.02mm	−40°C to +270°C	3950K ± 1%		110 0 0

Note: Dissipation Factor and Maximum Power ratings for these ring-lug assemblies depend on mounting conditions; see the per-part datasheet (PDF icon above) for thermal specifications.

Hex Nut Assemblies — Threaded Mounting

ATI's hex-nut NTC thermistor assemblies thread directly into a metal block, fluid manifold, or transformer winding with standard machine-thread hardware — no separate clamp, bracket, or thermal-paste step. A glass-encapsulated thermistor head is permanently welded to a brass hex nut, giving the assembly the durability and corrosion resistance needed for industrial fluid and electrical-equipment temperature sensing. Four thread sizes are stocked off-the-shelf: ATH10KHN4 (M4), ATH10KHN6 (M6), ATH10KHN10 (M10), and ATH10KHN12 (M12) — all 10 kΩ @ 25 °C with B = 3990 K, matching the standard 10 K thermistor curve used by most temperature controllers. Bare leads are copper-coated for direct solderability, eliminating the need for connector crimping in low-volume installations. Typical applications: transformer winding temperature monitoring, motor stator hotspot detection, hydraulic-oil and lubricant temperature measurement, HVAC duct and ambient air sensing, brewing kettle and food-grade fluid temperature, immersion heater feedback, and other industrial-instrumentation use cases where a rugged screw-in temperature probe is required.

Part Number (Thread Size)	Nominal R @ 25°C	B Value @ 25 / 50°C	Data- sheet	In Stock	Buy Now
ATH10KHN4 M4 thread	10K ± 1%	3990K ± 1%		27
ATH10KHN6 M6 thread	10K ± 1%	3990K ± 1%		5
ATH10KHN10 M10 thread	10K ± 1%	3990K ± 1%		10
ATH10KHN12 M12 thread	10K ± 1%	3990K ± 1%		10

Other Types — Metal Cap Housing

The ATSC230K-100 stainless-steel capped thermistor is a fully sealed NTC assembly engineered for harsh-environment temperature sensing — acid exposure, moisture, condensation, food contact, chemical wash-down, and outdoor weather survival. A glass-encapsulated 230 kΩ thermistor head (B = 4170 K, ideal for higher-temperature sensing ranges where 10 K self-heats too much) is hermetically enclosed inside a stainless-steel sheath with a rectangular mounting flange and bolt hole for fast panel- or wall-mount installation. Leads exit through a pair of 26 AWG heavy-duty PVC-insulated wires terminated in a two-pole female connector for plug-and-play wiring to a controller or DAQ. Both wire length and cap geometry are fully customizable per the customer's drawing — standard for OEMs building food-and-beverage equipment, marine instrumentation, semiconductor wet-processing tools, medical autoclave-tolerant sensors, pharmaceutical reactors, and outdoor industrial enclosures where a sealed, rugged, drop-in temperature probe is required.

Part Number	Nominal R @ 25°C	B Value @ 25 / 85°C	Data- sheet	In Stock	Buy Now
ATSC230K-100 Metal cap, PVC wire	231.5 ± 16.9K	4170K		50

Frequently Asked Questions — NTC Thermistors

What is the difference between NTC and PTC thermistors?

NTC (Negative Temperature Coefficient) thermistors decrease in resistance as temperature rises, making them ideal for temperature sensing and measurement. PTC (Positive Temperature Coefficient) thermistors increase in resistance with temperature, and are typically used for overcurrent protection or self-regulating heating elements. For precision temperature measurement in industrial and medical applications, NTC thermistors are the preferred choice due to their high sensitivity and fast response times.

What does the B value (Beta value) mean in a thermistor?

The B value (or Beta value) is a material constant expressed in Kelvin (K) that describes the sensitivity of an NTC thermistor across a temperature range. A higher B value indicates greater sensitivity. For example, our thermistors commonly feature B values of 3950K or 4066K. The B value is used alongside the Steinhart-Hart equation to accurately calculate resistance at any temperature within the operating range. Common B value ranges for our products are 3404K to 4177K.

Why choose glass encapsulated thermistors over epoxy encapsulated?

Glass encapsulated thermistors offer nearly zero long-term resistance drift compared to epoxy encapsulated models, which can drift measurably over months and years of operation. Glass encapsulation also enables a wider operating temperature range (up to 300°C vs. typically 150°C for epoxy), smaller bead sizes (from 0.8mm diameter), and better resistance to moisture and chemical exposure. For all precision applications, we exclusively use glass encapsulation in our thermistors and thermistor assemblies.

What resistance value should I choose — 5K, 10K, or 100K?

The most commonly used value is 10K ohm (at 25°C), which is the standard for TEC controllers, laser diode modules, and general-purpose temperature sensing. 100K thermistors are preferred for applications requiring very low self-heating or where higher impedance is needed, such as battery monitoring at low temperatures. 5K thermistors are sometimes used in lower-impedance circuits. For compatibility with our TEC controllers, 10K is the standard recommendation.

What is the operating temperature range of your thermistors?

Our glass-encapsulated NTC thermistors cover a wide operating range depending on the model. Standard models operate from -40°C to +250°C. High-sensitivity small-bead models (Φ0.8mm) cover -55°C to +250°C. High-temperature models extend coverage up to +300°C. Thermistor assemblies with metal cap housings maintain performance across the full -40°C to +250°C range even in harsh environments with moisture or chemical exposure.

Can I order custom thermistor assemblies with specific wire lengths or connectors?

Yes, Analog Technologies offers fully customized thermistor assemblies. You can specify custom wire lengths (in mm), wire gauge (standard is 26 AWG PVC insulated), housing material (stainless steel, metal cap, etc.), connector type, and resistance value. Minimum order quantities apply for custom designs. Please contact our sales team at sales@analogti.com or call (408) 748-9100 to discuss your requirements.