A pressure sensor is a device that measures the pressure of a gas or liquid. Pressure is an expression of the force required to prevent a fluid from expanding, and is usually expressed in terms of force per unit area. The pressure sensor usually functions as a transducer, which generates a signal based on the applied pressure. For the purposes of this article, such signals are electrical signals.
Pressure sensing is useful in meteorological instruments, airplanes, automobiles, and any other machinery that implements a pressure function. It is also the requirement of the use of this product, the pressure sensor needs very strict test requirements. However, there are different types of pressure sensors, different product packages, different types of test sockets, and different test methods:
1. Absolute pressure sensor.
The sensor measures the pressure relative to an ideal vacuum.
2. Gauge pressure sensor.
The sensor measures the pressure relative to atmospheric pressure. A tire pressure gauge is an example of gauge pressure measurement; when it indicates zero, the pressure it measures is the same as the ambient pressure.
3. Vacuum pressure sensor.
This term can cause confusion. It can be used to describe a sensor that measures pressure below atmospheric pressure and shows the difference between low pressure and atmospheric pressure, but it can also be used to describe a sensor that measures absolute pressure relative to vacuum.
4. Differential pressure sensor.
The sensor measures the difference between two pressures, and each pressure is connected to both sides of the sensor. Differential pressure sensors are used to measure many characteristics, such as the pressure drop between the oil filter or the air filter, the liquid level (by comparing the pressure above and below the liquid) or the flow rate (by measuring the pressure change on the limiter). Technically speaking, most pressure sensors are true differential pressure sensors; for example, an instrument pressure sensor is just a differential pressure sensor with one side open to the surrounding atmosphere.
5. Seal the pressure sensor.
The sensor is similar to the instrument pressure sensor, except that it measures the pressure relative to some fixed pressure, rather than the pressure relative to the surrounding atmospheric pressure (which varies according to location and weather).
The way the sensor uses the test socket to cooperate with the test:
1. On-board online test;
As with conventional chips, on-board functional testing is required. Such a test can better simulate the working state of the chip when the product is in normal use. As mentioned in the previous article, you only need to remove the chip from the test board, and then install the test socket on the PCB. This kind of test is used by most test socket users. The test seat needs to perfectly match the shape and size of the pressure sensor. At the same time, the test seat avoids the position of the sensor probe to better match the test and simulate the real test environment during user testing.
2. Aging test;
The use environment of the pressure sensor is harsh, and the actual use industry also has high requirements on the sensor, so the reliability and service life of the sensor are very high. Therefore, sensor manufacturers must perform aging tests on their products. The aging tests generally focus on high temperature, low temperature, pressure, special environments, and stress and humidity tests. After the sensor test socket is loaded with the manufacturer's sensor chip, it is placed in the test environment for an accelerated aging test to obtain the normal use time of the sensor.