Thick-film Temperature Sensors Research Articles

Studies on the Platinum Thick Film Sensor Conformally Written by Laser Micro-Cladding: Formability, Microstructure, and Performance

In this paper, laser micro-cladding technology (LMC) was conducted to prepare high-temperature Pt thick film sensors in situ. The formability, microstructure, sintering mechanism, and electrical properties of the LMCed Pt thick films were first studied systematically. Results indicated that with the increase of laser power density, the sintering degree of the Pt thick film increased obviously, improving its adhesion strength and reducing its resistivity. However, when the laser power density exceeded the threshold, holes or grooves were formed in the Pt film, leading to the degeneration of its properties. A Pt thick film with good adhesion strength, excellent conductive networks, and the minimum resistivity (46 ± 2 μΩ·cm) was obtained at a laser power density of 1.37 × 106 W·cm-2. Then, Pt thick film temperature sensors (including Pt thermal resistance temperature (RTD) and Pt-Pt10%Rh thermocouple sensors) were conformally prepared by LMC. Their temperature-sensing performance became stable after the initial high-temperature calibration, with a linearity of 0.9985 for the RTD with a TCR of 2.46 × 10-3/°C (at 920 °C) and a linearity of 0.9905 for the thermocouple with a Seebeck coefficient of 9.7 μV/°C, both of which are better than that made by direct DC magnetron sputtering deposition. Therefore, this work provides a novel feasible way to conformally integrate high-performance Pt film sensors in situ.

Low-temperature sintered NTC ceramics for thick film temperature sensors

Printed thick film NTC thermistors and multilayer devices are frequently used for temperature control in hybrid circuits. NiMn2O4 and substituted spinels are the most established materials for this application. For low-temperature sintering at 900 °C the shrinkage behavior of the thermistor material has to be adjusted by the addition of proper sinter additives. We investigated the chemical stability of NiMn2O4 and substituted spinels in air between 25 °C and 1200 °C. The compound NiMn2O4 is stable from 700 °C to 970 °C only and interacts with the sinter additives. Stable cubic spinels were found in the system ZnxNi0,5Co0,5Mn2-zO4. Addition of liquid phase sintering additives to the spinel powders results in complete densification at 900 °C. No chemical interaction between spinel and additive was observed. The effect of Cu-substitution into the spinel was also investigated. Functional NTC pastes were printed on alumina substrates and post-fired at 900 °C. The NTC thermistor films have a sheet resistivity of about 300 kOhm/sq and B = 3300 K. The firing behavior, microstructure formation and electric properties of NTC thick films will be reported.

Preparation of iron silicide thick film temperature sensor

Preparation of iron silicide thick film temperature sensor

Thick-film temperature sensors on alumina and LTCC substrates

The electrical and microstructural characteristics of 1 kΩ/sq. thick-film thermistors with high positive or negative temperature coefficients of resistivity, i.e., PTC 5093 (Du Pont) and NTC 4993 (EMCA Remex), fired on alumina or co-fired on “green” low-temperature co-fired ceramic (LTCC) substrates, are compared. The active phase in both materials (the ruthenium oxide and the semiconducting spinel in the PTC and NTC thermistors, respectively) is not present in the dried films but is formed during firing. The differences in the measured electrical parameters (sheet resistivities, temperature dependence of resistivities and noise) of the thermistors, fired on alumina or on LTCC were attributed to the interactions between the thermistor layers and the glassy LTCC substrates. The inter-diffusion of oxides, mainly PbO and SiO 2, was confirmed by microanalysis.

Thick film heater elements and temperature sensors in modern domestic appliances

This paper describes the use of thick film heating elements in domestic appliances, and comparison is made of performance and cost between thick film and traditional heaters. Thick films are created by screen printing pastes, usually containing glass and metal powders, onto a flat substrate. A brief explanation of thick film technology is given. This technology has been used for many years in the electronics industry to produce circuits containing conductors, resistors and dielectrics. The structure of a thick film resistor makes it ideal for heating applications, and it may be deposited on a number of substrate materials. Experimental data demonstrating that thick films make effective and reliable heating elements and temperature sensors are presented. The combination of a thick film heating element with thick film temperature sensor on an insulated steel substrate is described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New Thick Film Temperature Sensor of Exhaust Valves in Fiat 126P

This paper presents the results of preliminary research carried out in the Department of Microelectronics at the Institute of Electronics of the Mining and Metallurgical University (AGH), Krakow, Poland, devoted to designing and producing a thick‐film temperature sensor for the functioning of exhaust valves in the Polski Fiat‐126 motor‐car.

New thick-film temperature sensors applied in some hybrid measurement devices : Janusz J. Gondek and Marek A. Wójcicki. Electrocomponent Sci. Technol.10, 95 (1983)

New thick-film temperature sensors applied in some hybrid measurement devices : Janusz J. Gondek and Marek A. Wójcicki. Electrocomponent Sci. Technol.10, 95 (1983)

New Thick Film Sensors

Various thick film sensors which are under development in the Microelectronics laboratory of the University of Oulu are described. More details are included on the capacitive thick film temperature sensor which is in the application stage. Other thick film sensors at present in the material development stage are the resistive humidity sensor, the gas sensor and the ion selective sensor.