CN101487812B - Test system for resistivity-temperature characteristics and air-sensitive characteristics of components - Google Patents

Abstract

The invention relates to a testing system for temperature resistance characteristics and gas sensitivity characteristics of components, which includes two air inlets, a gas mixing chamber, a vacuum reaction chamber, a gas concentration tester, a test probe device, a temperature control board, a temperature controller and computer, the two air inlets are respectively connected to the air mixing chamber through valves, and flow meters are respectively arranged at the two air inlets, the air mixing chamber is connected to the vacuum reaction chamber through the valve, and the air pump is connected to the vacuum reaction chamber through the valve. A temperature control board for heating the components to be tested is fixed in the vacuum reaction chamber, a gas concentration tester is installed near the temperature control board, a test probe device is also fixed in the vacuum reaction chamber, and the temperature control board is connected to the computer Controlled by a temperature controller, the two probes of the test probe device are used as contact electrodes of the components to be tested, and are connected to a multimeter, which is connected to a computer. The invention can more accurately control and measure the gas content in the reaction chamber in real time, the electrode contact is more reliable, and the two functions of the temperature resistance characteristic test and the gas sensitivity characteristic test are integrated into the same device, which can realize full data recording automation.

Description

A testing system for temperature resistance characteristics and gas sensitivity characteristics of components

technical field

The invention relates to a characteristic testing device of a gas sensor.

Background technique

The temperature resistance characteristic test device of the gas sensor usually includes two main parts: the heating part and the resistance test part. The main testing instruments currently on the market (such as the FQJ/2 unbalanced bridge heating device of Hangzhou Jingke Instrument Co., Ltd.) all require manual counting. Due to human subjectivity and hysteresis of response, sampling is inaccurate and sampling points are relatively small. Moreover, such equipment cannot precisely control the heating rate, which limits the scope of use of the equipment.

The gas-sensing characteristic test device includes three main parts: air intake part, electrical performance test part, and heating part.

(1) At present, there are two air intake methods in China: one is to calculate the air intake according to the volume of the reaction chamber, inject the detection gas with a micro-sampler, and fill the reaction chamber evenly with the gas through diffusion or with the help of a fan. (See the paper, Huijuan Xia, Yan Wang, Fanhong Kong, Shurong Wang, Baolin Zhu, Xianzhi Guo, Jun Zhang, YanmeiWang, Shihua Wu, Au-doped WO3-based sensor for NO2 detection at low operating temperature, Sensors and Actuators B 134( 2008) 133-139.) The other is to evacuate the reaction chamber first, and then directly inject the pre-mixed gas into the reaction chamber with a mass flow meter. (see patent, 200710063698.1). Due to the limitation of the purity of the gas source, the precision limitation of the micro sample injector (mass flow meter), the airtightness limitation of the whole device and the maximum vacuum degree that can be achieved by the single-stage vacuum pump, the concentration of the gas in the final reaction chamber and the front-end theoretical calculation The obtained concentration is biased, so the injection method of this kind of detection gas needs to be improved.

(2) To test the electrical performance, it is necessary to lead out the two electrodes of the component. At present, the method of welding metal wire or pressing sheet contact is generally used. The steps of welding metal wires are complicated, and the resistance of components is very sensitive to the quality of electrode contact. The quality of solder joints directly affects the testing of electrical properties. Ordinary pressure type can not guarantee good electrical contact.

(3) At present, the measurement of the temperature resistance characteristics and gas sensitivity characteristics of components requires the use of two separate test devices, which is inconvenient and expensive to test.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, to provide a more accurate control and real-time measurement of the content of the gas in the reaction chamber (ppm level), the electrode contact is more reliable, and the temperature resistance characteristic test is combined with the gas The two functions of the sensitive characteristic test are integrated in the same device to realize the fully automatic gas sensor characteristic test device for data recording.

For this reason, the present invention adopts following technical scheme:

A test system for temperature resistance and gas sensitivity characteristics of components, including two air inlets, a gas mixing chamber, a vacuum reaction chamber, a gas concentration tester, a test probe device, a temperature control board, a temperature controller and a computer. The two air inlets are respectively connected to the gas mixing chamber through valves, and flow meters are respectively arranged at the two inlets. The gas mixing chamber is connected to the vacuum reaction chamber through valves, and the air pump is connected to the vacuum reaction chamber through valves. A temperature control board for heating the components to be tested is fixed in the room, a gas concentration tester is installed near the temperature control board, and a test probe device is fixed in the vacuum reaction chamber. The temperature control board is controlled by the temperature connected to the computer. The control of the device, the two probes of the test probe device are used as the contact electrodes of the components to be tested, and are connected to the multimeter, which is connected to the computer.

As a preferred embodiment, in the test system for temperature resistance characteristics and gas sensitivity characteristics of components and parts of the present invention, the test probe device includes a stand, a clamping mechanism arranged on the stand, and two probe arms fixed by the clamping mechanism , two spring probes respectively fixed on the probe arm through the probe base; the probe arm is a mechanical device with adjustable arm distance; Testing the volt-ampere characteristics of the components to be tested; the test system also includes a constant current and steady current source, which is used to cooperate with testing the gas-sensing characteristics of the components to be tested under constant operating current.

The present invention has following outstanding technical effect:

1. Through the use of intelligent instruments and computers, it can realize the integration of a series of characteristic tests such as gas sensing characteristics and temperature resistance characteristics, intelligentization, full automation of recording data, and simplification of data processing.

2. Through the accurate measurement of the gas concentration in the vacuum reaction chamber, the gas-sensing characteristics of the tested device can be more accurately quantified.

3. Through the ingenious use of spring probes, the practical problem of extremely difficult and unreliable test leads for components is solved.

Description of drawings

Fig. 1 is the structural block diagram of the temperature resistance characteristic of components and parts of the present invention and the gas sensitivity characteristic testing system;

The front view of the test probe device that Fig. 2 adopts in the present invention;

The side view of the testing probe device that Fig. 3 the present invention adopts;

Fig. 4 is a structural block diagram of another embodiment of the testing system of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Referring to Fig. 1, the test system of the present invention comprises two air inlets, and air inlet 1 is used for feeding detection gas; Air inlet 2 is used for feeding carrier gas; Accurate mass flow meter 3; Mass flow meter 4; Gas mixing chamber 5; a vacuum reaction chamber with a cover connected to the gas mixing chamber 5; a gas detector, a heating aluminum plate (or called a temperature control plate), a thermocouple for measuring the temperature of the heating aluminum plate, Test probe device (also called contact electrode device); PID intelligent temperature controller (with serial communication interface) for temperature adjustment according to the temperature measured by thermocouple; digital multimeter; computer; connected with vacuum reaction chamber through valve pump; pressure gauge or vacuum gauge to measure the pressure of the vacuum reaction chamber.

During the test, first close the valves 6, 7, 8, and 9, and open the valves 10, 11. Use a vacuum pump to evacuate the gas mixing chamber 5 and the vacuum reaction chamber. When the required vacuum value is reached, close valves 10 and 11 and open valves 6, 7, 8 and 9. According to the needs of the test, the mass flow meter is used to pass a specific proportion of gas into the gas mixing chamber for pre-mixing. After the mixing is complete, open the valve 11, pass the gas into the vacuum reaction chamber, and use the gas detector to measure the gas content in the reaction chamber in real time.

2 and 3, the components 27 are placed on the surface of the heating plate 26 below the probe arm 23, the distance between the probe arms 23 is adjusted to match the distance between the electrodes of the device, and the iron clamp 22 is moved downward until the probe The needle 25 contacts the surface of the electrode. Through the programming and setting of the PID intelligent temperature controller, the components 27 are heated accurately. And transfer the temperature-time value to the computer.

The two probe bases 24 are connected with the outside world through a terminal installed on the inner wall of the reaction chamber. And connected to the ground wire and resistance test terminal of the digital multimeter respectively. The digital multimeter is connected to the computer. The resistance-time value can be recorded in real time, and the resistance-time curve can be observed.

The upper part of the vacuum reaction chamber is a flange-connected reaction chamber cover. The specifications of the vacuum reaction chamber are: diameter 200mm, height 150mm.

The maximum power of the heating plate is 400w, and the reliable heating range is 0-350°C. The specifications are: length 95mm, width 95mm, height 12mm.

PID temperature controller has an accuracy of 0.5, 400 curves can be programmed, with serial interface and interface software.

Digital multimeter (DMM) resistance range 0-99 megohms. Accuracy error 0.025%, with serial interface and interface software.

The gas detector can freely replace the test probe for parameter testing of different gases.

The probe model is P100-J, and the contact resistance is 50 milliohms.

How to use the test system of the present invention will be described in detail below.

1. Connect the reaction gas and carrier gas to inlet 1 and inlet 2 respectively.

2. Use a vacuum pump to evacuate the gas reaction chamber and gas mixing chamber to the required vacuum degree. The pressure gauge is used to display the vacuum degree of the reaction chamber.

3. Calculate the ratio of reaction gas and carrier gas according to the required reaction gas concentration. Use a mass flow meter to pass the two gases into the gas mixing chamber to mix, and then pass into the reaction chamber until the pressure gauge shows the required pressure.

4. Use a gas concentration detector (GAXT series high-precision waterproof single gas detector from York, Canada) to read the exact concentration of the gas in the reaction chamber. This is the original part of the present invention. The gas concentration is directly detected near the gas sensor in the reaction chamber. It avoids the limitation and interference of all surrounding experimental conditions, and reduces the accuracy requirements of other equipment in the system. If it is unnecessary to install a multi-stage vacuum pump to ensure that the vacuum reaction chamber is pumped to a high vacuum, it saves experimental time; unnecessary Buy expensive accurate mass flow meters etc. Moreover, the concentration measured by this method is direct, and the concentration calculated by the front end can only be an approximate value. At the same time, with the pressure gauge, this gas concentration detector can more intuitively judge whether the experimental device is leaking.

The above is a new set of gas injection system solutions.

5. There are 6 double-ended terminals on the wall of the reaction chamber. One end of the six terminals is respectively connected to the positive and negative poles of the heating plate and the positive and negative poles of the thermocouple. Probe holders (2 pieces). The external end corresponds to the positive and negative poles of the relay output of the PID intelligent temperature controller. Thermocouple input positive and negative. The ground wire and resistance file of the digital multimeter.

6. Inside the vacuum reaction chamber: To install the components before the test, first turn on the multimeter, and then place the device at a proper place under the probe. Adjust the spacing of the probe arms according to the electrode spacing on the device. Move the iron clip downwards while observing the multi-purpose indication, until the multi-purpose indication becomes a finite value, stop moving the iron clip. This wiring method is the first of its kind in this field. The invention cleverly utilizes the mature PCB probes in China to simplify the reliable contact method that originally requires soldering metal wires, and the theory and practice prove that the probe contacts are electrically reliable. (as the four-probe tester that has been widely used in scientific experiments just adopts similar probe contact.) The detailed composition of this part is seen accompanying drawing 2, and test probe device comprises: iron frame platform 21; Iron clip 22; Probe arm 23 ; Probe base 24 ; Spring probe 25 . The probe arm 23 is a mechanical device with adjustable arm distance. The distance between the left and right arms is flexible and adjustable, and the adjustment range is 1-15mm, which can adapt to most devices under the integrated circuit technology. The probe base 24 is mounted on the lower end of the spring probe arm 23 , and the spring probe 25 is inserted into the probe base 23 . If used for a long time, the probe will lose its elasticity. The spring probe 25 can also be easily replaced to ensure highly reliable electrical contact.

7. When testing the gas-sensing characteristics, first evacuate the reaction chamber, and then adjust the PID temperature controller to an appropriate temperature. After the temperature is stabilized, turn on the multimeter, and continuously transmit the electrical quantity to the computer at a sampling rate of 1sa/s. At this time, follow step 3 to inject an appropriate amount of gas into the reaction chamber, and draw the gas-sensing characteristic curve in real time. After the reaction is stable, the gas is pumped out with a vacuum pump, and the carrier gas is introduced to test the gas sensitivity recovery characteristics of the device. Then all the experimental data are completely saved in the computer for further processing.

8. When testing the temperature resistance characteristics, set the temperature rise curve and temperature rise threshold of the PID temperature controller according to the test needs. And connect the PID temperature controller to the computer to output the temperature-time value (1sa/s). Simultaneously turn on the digital multimeter and connect it to the computer to output the resistance-time value (1sa/s). After the experiment is finished, save the two files as a spreadsheet file, and use the spreadsheet software to easily obtain the resistance-temperature value and the corresponding curve, which is the third bright spot of the present invention. PID intelligent temperature controller (Japan Shimaden fp-23) has high control precision, and can set various shapes of heating curves. The digital multimeter is a high-precision multimeter with a sampling rate of 5sa/s (Ultra ut-70d).

9. Test function extension

The electrode based on the device has been reliably led to the terminal outside the reaction chamber, so it can be conveniently and flexibly matched with other instruments to test other characteristics of the device. For example, the I-V characteristics of the device can be tested with a cathode and anode polarizer, and the gas-sensing characteristics of the constant operating current of the device can be tested with a constant current and steady current source, etc., see Figure 4.

Claims (4)

1. A test system for temperature resistance and gas sensitivity characteristics of components, including two air inlets, a gas mixing chamber, a vacuum reaction chamber, a gas concentration tester, a test probe device, a temperature control board, a temperature controller and a computer , the two air inlets are respectively connected to the gas mixing chamber through valves, flowmeters are respectively arranged at the two inlets, the gas mixing chamber is connected to the vacuum reaction chamber through the valve, and the air pump is connected to the vacuum reaction chamber through the valve. A temperature control board for heating the components to be tested is fixed in the vacuum reaction chamber, a gas concentration tester is installed near the temperature control board, and a test probe device is also fixed in the vacuum reaction chamber. The temperature control board is connected to the computer. The control of the temperature controller, the test probe device includes a stand, a clamping mechanism arranged on the stand, two probe arms fixed by the clamping mechanism, and two probe arms respectively fixed on the probe arm through the probe base. A spring probe, the two spring probes are used as contact electrodes of the component to be tested, and connected with a multimeter, and the multimeter is connected with a computer. 2. The temperature resistance and gas-sensing characteristic testing system of components according to claim 1, wherein the probe arm is a mechanical device with adjustable arm distance. 3. The temperature-resistance characteristic and gas-sensing characteristic test system of components and parts according to claim 1, characterized in that, said test system further comprises a cathode-anodizer for cooperating with testing the volt-ampere characteristics of the components and parts to be tested. 4. The temperature-resistance characteristic and gas-sensing characteristic test system of components and parts according to claim 1, it is characterized in that, described test system also comprises constant-current steady-current source, is used for coordinating the testing component and parts under constant operating current Under the gas-sensing characteristics.

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