Thermal Conductivity Sensor for miniature Pirani gauge

General description

    The MTCS2300 pressure gauge, using thermal conductance measurement according to Pirani principle, is a dedicated MEMS device mounted in a small TO8 or TO39 package. The sensor incorporates one large micro-machined low stress silicon nitride membrane with two thin film resistors for heating and two reference resistors for compensation on silicon bulk using Ni-Pt resistors MEMS technologies in a miniature package. This MEMS structure, combined with simple CMOS standard integrated circuits for current source and temperature analysis, is a suitable choice for size-critical vacuum OEM sensing solution requiring ultra-low power consumption with an excellent signal-to-noise ratio and resistance to corrosive gas.

Applications

Miniature Pirani devices and sensors have applications including：

•Leak detection

•Propulsion

•Semiconductor manufacturing (e.g., sputtering chambers)

•Freeze dryers

•Vacuum meat packing machines

•Vacuum coating

•Load locks

In general, pressure measurement following Pirani principle in rough environments with power and size constraints, such as in analytical portable instruments or small mechanical pumping systems

Silicon Pirani gauge MTCS characteristics

The packaged sensor is available with different possible packaging options:

•Only the sensing die, realizing a miniature hot wire in air

•The sensing die with a silicon lid, creating a gap between the hot and cold part of 10 µm or 20 µm. These small gaps enhance the sensitivity of the Pirani principle at pressures between 100-1000 mbar

Features

•Extended measuring range from 10-4 to 1000 mbar

•MEMS Micro machined silicon sensor with perfect matching of the sensor geometry and sensor resistors

•Ultra small sensor gas volume such as < 0.1 cm³ 

•Pirani microwire-to-wall distance adjusted by silicon micromachining, down to 10 µm or 20 µm with excellent sensor reproducibility

•Ultra-low power consumption in operation (< 6 mW) due to the use of MEMS based silicon sensor with large integrated resistors such as 250 Ohms and small heated mass

•Ultra-fast response time < 50 ms

•Easy temperature compensation due to similar heating and reference resistors, realized in micro structured platinum-nickel thin film process

•Insensitive to mounting position

•High shock survivability (>1000 G) due to small size

•Resistance to corrosive gas as Hydrogen, using gold contact

MTCS2301/MTCS2302 sensor electrical characteristics

Sensor package information

MTCS sensor in TO8 metallic header, with 8 isolated leads (TO8 size)

Package size:

External diameter: 13.00 mm

Internal diameter: 10.85 mm