Yixing City, 214214, Jiangsu, China-September 22, 2026

Twenty bare sensing elements were soaked at 500 °C for 300 hours. Average resistance and B-value drift stayed below 0.2%, and every sample remained inside the ±2.5% acceptance window — so the batch was qualified.

We announced today that our newly developed high-temperature single-ended NTC thermistor has completed type-test validation and is now moving into volume production.

The part is a single-ended, lead-free glass-bead thermistor with a 2.3 mm sensing head, specified at R200 °C = 1.0 kΩ ±2.5% and B100/200 °C = 4537 K. It is aimed at applications where the sensing element itself — not a packaged probe —sit in an extremely hot environment.

What was tested

A type test was carried out on 20 production-representative samples on July 23, 2026, to the product type-test plan. The samples were taken down to the sensing element: the housing and the fiberglass sleeve were removed, so the NTC element was exposed directly to the test environment rather than being shielded by the assembly.

Test item:

• high-temperature storage

Condition:

• bare NTC element held in a 500 °C environment for 300 hours

Sample size:

• 20 pcs submitted, 20 pcs inspected

Sample category:

• material (component level)

Acceptance criteria:

• no damage, no oxidation; R value at 100 °C and 200 °C and B100/200 °C within ±2.5% of initial values

Results

Parameter	Average deviation after 500 °C / 300 h	Largest single-sample deviation	Limit
R @ 100 °C	−0.09%	−2.20% (sample 8#)	±2.5%
R @ 200 °C	−0.16%	−1.64% (sample 8#)	±2.5%
B100/200 °C	+0.03%	−0.22% (sample 8#)	±2.5%

Visual inspection found no loosening, wear, deformation or breakage at the riveted joints. All 20 samples met the acceptance criteria and the batch was judged qualified.

In practical terms: after 300 hours at 500 °C, the average resistance reading moved by less than two parts in a thousand, and the B value — the parameter that determines how the sensor tracks temperature — stayed essentially unchanged.

Why a 500 °C NTC is hard to build

Reading the result is easy; producing it is not. A thermistor that is merely rated for high temperature and a thermistor that still reads the same after hundreds of hours at 500 °C are two very different products. Four problems have to be solved at the same time.

The ceramic drifts from the inside. NTC behaviour comes from charge exchange between transition-metal oxide sites in the ceramic (Mn3+/Mn4+ in the common spinel systems), and both the resistance and the B value are tied directly to that balance. At 500 °C the material is pushed to rebalance itself: cation migration, oxidation and slow re-sintering all move the very ratio the sensor depends on, and they move faster the hotter it gets. Holding R and B inside ±2.5% after 300 hours is decided in the powder and the firing profile long before the test.

The electrode and the lead have to stay put. At the bead, the electrode must keep an ohmic contact. At 500 °C, interdiffusion between electrode and ceramic, oxide growth, and the mismatch in thermal expansion between ceramic, electrode and lead all add contact resistance that drifts with time — and a few percent of contact drift looks exactly like a few percent of element drift on the meter.

The glass has to survive with the part, not just seal it. The bead has to wet and seal the element without reacting with it, match thermal expansion closely enough to survive repeated heating and cooling without micro-cracking, and hold its shape at 500 °C while staying thin enough to keep the thermal response fast. Voids, bubbles and micro-cracks are the classic failure mechanisms here, and they are usually invisible on the bench.

Solving all four at the same time — and proving it over 300 hours — is what separates a laboratory sample from a shippable part. That is the work behind the result above.

Why this matters

Most single-ended NTC thermistors are built around epoxy or resin coatings whose limits are far below 500 °C. When the sensing element itself can survive that environment, the sensor can be placed closer to the heat source:

• appliance heating systems, cookware and small kitchen appliances
• water heaters, boilers and heating modules
• industrial ovens, heating stages and process equipment
• any design where a probe assembly would be too slow or too bulky

Because the tested configuration was the bare element, the result isolates the intrinsic high-temperature capability of the sensor rather than the thermal protection offered by a housing.

From validation to volume production

The feasibility study is complete and the type test has passed, so this part is cleared for mass production. The process window and the inspection criteria that produced these 20 qualified samples are being carried over to the production line, and the same acceptance standard — no damage or oxidation, and R and B within ±2.5% of initial values after 500 °C / 300 h — applies to mass-production lots.

Engineering samples are available now. Mass production is scheduled to begin in [month, year]; please contact us for MOQ, lead time and the full type-test report.

About Us

For over 20 years, through continuous investment in research and development and process innovation, we have gradually built a complete industrial chain from chip design to various components, achieving a strategic transformation from a “single product supplier” to an “industry solution service provider”. The dual breakthroughs in production capacity and technology have driven the growth of the enterprise into a leading manufacturer of sensitive components in the domestic market.

Media Contact
Company Name: Wuxi Xuyang Electronics Co., Ltd.
Contact Person: Media Relations
Email: Send Email
Country: China
Website: https://www.ntc-thermistor.com/