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Advantages of sputtered film pressure sensor compared with adhesive strain pressure and diffused silicon pressure

Published on: December 26, 2018 by Zetian sensing

There are many manufacturing processes and complicated processes for pressure sensors. The pressure sensors which also adopt the strain principle can be divided into three types: adhesive strain gauge, semiconductor diffusion silicon piezoresistive type and sputtered film type. These different processes of pressure sensors, the following Zetian sensor for you to briefly describe their advantages and disadvantages.

The adhesive strain gauge pressure sensor has been born for half a century and is the earliest type of pressure sensor. Its principle defect is the use of organic polymer substrate and viscose, not resistant to high temperature and poor long-term stability, large creep, generally used in low-cost, low-cost measurement system. Semiconductor diffused silicon piezoresistive pressure sensor The pressure sensitive element is made by diffusion on silicon wafer by semiconductor technology, and the pressure sensitive core body is packaged by lead wire and filled with silicon oil. The pressure sensitive core is encapsulated into the pressure connector through an "O" type rubber sealing ring to form a pressure sensor. Its working principle is: when the pressure acts on the sensitive core, the resistivity of the diffusion resistance changes, thus causing the change of the sensitive resistance, realizing the change of the pressure change into the change of the electrical signal. The product is suitable for mass production, low cost, large output, suitable for micro pressure, low pressure varieties. However, its disadvantages are also very prominent. Firstly, because its sensitive resistance is diffused by semiconductor silicon, its temperature coefficient of resistance is very poor. When the temperature exceeds 85 ℃, the temperature compensation is very difficult. When the temperature is lower than - 45 ℃, the resistivity of diffusion silicon changes greatly and irregularly, which can not meet the requirements of environmental temperature resistance. Secondly, due to the brittleness of semiconductor silicon and the reason of using isolation film filled with silicone oil, the product can not resist high-strength vibration and impact, and the frequency response is also low.

 Sputtering film pressure sensor

Sputtering thin film pressure sensor It is a high stable variety developed by the combination of thin film technology and semiconductor technology in recent 20 years. The pressure sensitive core is formed by depositing insulating and sensitive films on high strength corrosion-resistant stainless steel by ion beam sputtering equipment instead of traditional adhesive organic substrate and metal sensitive gate, and then sputtering protective film to protect sensitive film. Secondly, the sensing core and stainless steel pressure nozzle are welded into a whole by laser welding or plasma welding. Therefore, the sputtered thin film pressure sensor has the following characteristics:

1. The sputtered film pressure sensor has good long-term stability, wide working temperature, high precision and good repeatability, Because the insulation film and substrate, sensitive film and insulating film are directly deposited together in high vacuum environment, the combination of atomic force between each film layer eliminates the creep effect caused by adhesive tape. At the same time, the sensitive film is protected by silicon dioxide protective film in high vacuum environment, so it is characterized by high precision, good repeatability, good long-term stability and wide working temperature (through different settings) The pressure sensitive core with temperature resistance from - 200 ℃ to 400 ℃ can be achieved. It can work under high temperature and high pressure for a long time.

2、 The sputtered film pressure sensor is resistant to high-intensity vibration and impact, no leakage and corrosion resistance. Since the film pressure sensor is welded into a whole by laser welding or plasma welding, the sputtered film pressure sensor does not have any "O" type rubber seal ring and is not filled with silicone oil. The pressure medium acts directly on corrosion resistance and rust resistance On the steel sensitive core, the product can withstand high-strength vibration and impact, and there is no risk of leakage.

3. The sputtering film pressure sensor has good temperature characteristics. The temperature drift of the film pressure sensor is less than 0.02% / ℃ in the whole temperature range from - 200 ℃ to 400 ℃ due to the semiconductor technology and laser resistance modulation technology.

4. Sputtered film pressure sensor has real measurement and high frequency response. Because the pressure medium acts on the sensitive core of corrosion-resistant stainless steel directly, there is no isolation film and filling liquid, so the measurement is true and frequency response is high. Through the design, the frequency response can reach more than 20kHz.

Sputtered thin film pressure sensor is very suitable for measuring large amount of pressure. However, it is not suitable to use sputtering film pressure sensor when the pressure range is below 400kPa. This article originates from Zetian sensing All rights reserved. Please keep the source.