When learning and using pressure sensors, we often hear the term "temperature drift." But what is temperature drift, and how is it caused in pressure sensors, specifically diffused silicon pressure sensors?
Temperature drift refers to the unstable zero-point caused by temperature effects.
The temperature drift in diffused silicon pressure sensors mainly comes from two aspects:
The first aspect is the temperature drift of the components themselves.
The second aspect is the stress generated during the expansion process of the sensor. The core component of the sensor is the pressure chip, which is sensitive to temperature changes and will drift with the change in temperature. Additionally, during the packaging process, the sensor needs to be filled with silicone oil to transfer the force from the pressure diaphragm to the pressure chip. The silicone oil will undergo thermal expansion and contraction with temperature changes, thereby generating stress that acts on the pressure chip and causing drift in the sensor. Moreover, the pressure chip is connected to the sensor base with adhesive. Since the pressure chip and the sensor base are made of different materials with different coefficients of thermal expansion, there will be stress between the materials under temperature changes, resulting in a certain amount of temperature drift. These are the main sources of temperature drift in diffused silicon pressure sensors.
To reduce the temperature drift of pressure sensors to a certain extent, technicians should minimize the volume of the oil-filled core body to reduce the amount of oil used. They should also choose suitable adhesive to minimize the stress generated during the bonding process of the pressure chip. When selecting the material of the sensor base, they should consider materials with coefficients of thermal expansion similar to that of the pressure chip to reduce the temperature drift.