Quick response temperature sensor based on conductive silver paste sintering

Abstract

The invention belongs to the field of temperature sensor design, and particularly relates to a quick response temperature sensor based on conductive silver paste sintering. In order to accurately obtain the temperature of a medium in real time, the response time needs to be concerned in the design process of a temperature sensor. According to the fast-response temperature sensor, a temperature probe is welded to the front end of a mounting base in a sealed mode, a connector is welded to the rear end of the mounting base in a sealed mode, a platinum resistor is fixedly sealed in an inner cavity of the temperature probe through sintered conductive silver paste, the cross section of the temperature probe and the cross section of the platinum resistor are the same in shape, and the gap between the temperature probe and the platinum resistor ranges from 0.25 mm to 0.3 mm. The gap size between the platinum resistor and the temperature probe in the transverse direction is smaller than the gap size in the axial direction; and the platinum resistor is connected with the connector through a lead. The response time of the sensor is fast and can reach 0.5 s, and the requirement for fast temperature measurement is met.

Description

Technical Field

[0001] The invention belongs to the field of temperature sensor design, and in particular relates to a fast-response temperature sensor based on sintering of conductive silver paste, which is designed to improve the response time of the sensor. Background Art

[0002] In the field of temperature measurement, platinum resistance temperature measurement is a common temperature measurement method. Platinum resistance has the advantages of high temperature measurement accuracy, good consistency, high stability, and strong anti-oxidation performance. The platinum resistor is sealed inside the metal temperature probe through insulating materials. The temperature of the measuring medium is transmitted to the platinum resistor through the temperature probe. The resistance of the platinum resistor changes in direct proportion to the temperature change, thereby converting the temperature signal into a resistance signal. The resistance signal is output by the electrical interface to achieve temperature measurement.

[0003] In order to accurately obtain the temperature of the medium in real time, the sampling frequency of the temperature needs to be increased. Therefore, the response time of the temperature sensor must meet the requirements. Therefore, attention should be paid to the response time during the design of the temperature sensor.

[0004] The temperature sensor response time is mainly determined by the following factors:

[0005] (1) Response time of platinum resistance element;

[0006] (2) The additional response time introduced when the platinum resistor is packaged into a temperature sensor, that is, the response time introduced after being assembled into a temperature probe assembly. Summary of the invention

[0007] The purpose of the present invention is to provide a fast-response temperature sensor based on sintering of conductive silver paste in order to improve the response time of the temperature sensor, reduce the response time of the platinum resistance element and the additional time introduced by the packaging.

[0008] The technical solution of the present invention is: a fast-response temperature sensor based on sintering of conductive silver paste, wherein the fast-response temperature sensor is sealed and welded with a temperature probe at the front end of a mounting seat, and is sealed and welded with a connector at the rear end of the mounting seat, a platinum resistor is fixedly sealed in the inner cavity of the temperature probe by sintering conductive silver paste, the temperature probe and the platinum resistor have the same cross-sectional shape, the gap between the two is between 0.25 mm and 0.3 mm, and the gap size between the platinum resistor and the temperature probe in the transverse direction is smaller than the gap size in the axial direction; the platinum resistor is connected to the connector through a wire.

[0009] Advantageously, the mounting base and the temperature probe are fixed by laser welding.

[0010] Advantageously, the mounting seat and the connector are fixed by laser welding.

[0011] Advantageously, the cross-sections of the temperature probe and the platinum resistor are rectangular.

[0012] Advantageously, the cross-sections of the temperature probe and the platinum resistor are circular.

[0013] Advantageously, in the sintering process, the conductive silver paste is filled into the inner hole of the temperature probe by vacuum filling, and then the platinum resistor is installed into the inner hole of the temperature probe and immersed in the conductive silver paste, and then vacuum degassing, standing, vacuum degassing treatment is performed, and finally curing and sintering are performed.

[0014] Advantageously, filling starts from the bottom.

[0015] Advantageously, multiple fillings are used.

[0016] Advantageously, the sintering temperature is strictly controlled according to the material sintering characteristic curve.

[0017] Beneficial effects of the invention: The invention has great practical application value. The sensor has a fast response time of 0.5s, which meets the demand for rapid temperature measurement. The sensor has strong environmental adaptability and adopts a fully sealed metal shell design, which is compatible with various media and can meet the assessment of high temperature, low temperature, damp heat, mold, and salt spray tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an oblique view of a fast-response temperature sensor;

[0019] Figure 2 It is a schematic diagram of the internal structure of the fast-response temperature sensor;

[0020] Figure 3 This is the internal schematic diagram of the temperature probe;

[0021] Figure 4 Schematic diagram of signal transmission of fast-response temperature sensor.

[0022] 1. Platinum resistor, 2. Conductive silver paste, 3. Temperature probe, 4. Mounting base, 5. Connector DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] See also Figure 1-3 The fast response temperature sensor embodiment shown includes a platinum resistor 1, a conductive silver paste 2, a temperature probe 3, a mounting base 4 and a connector 5. The platinum resistor 1 is assembled to the front end of the inner cavity of the temperature probe 3 by sintering the conductive silver paste 2. The assembly is fixed at the front end of the mounting base 4 by laser welding. The connector 5 is fixed at the rear end of the mounting base 4 by laser welding. The platinum resistor 1 and the connector 5 are connected inside the mounting base 4 by a wire.

[0025] The temperature probe 3 is the part that connects the product to the outside world and is used to protect the platinum resistor 1 and transfer heat. To meet the adaptability of temperature, pressure and corrosive environment, the temperature probe 3 is made of low thermal melting value material, such as stainless steel, which has good environmental adaptability and thermal conductivity.

[0026] The structural design and material selection of the temperature probe 3 have a great influence on the response time of the sensor. The influence of the lateral size of the temperature probe 3 on the response time increases approximately linearly. The larger the lateral size of the temperature probe, the longer the response time. The structural size design of the temperature probe mainly considers the size of the platinum resistor and the environmental pressure. The cross section of the platinum resistor 1 is often rectangular, so the cross section of the temperature probe 3 is designed to be rectangular, and the gap between the temperature probe 3 and the platinum resistor 1 in the axial and lateral directions can be minimized to improve the response time of the sensor.

[0027] The inner hole size of the temperature probe 3 is designed according to the outer size of the platinum resistor 1. There is a gap between the platinum resistor 1 and the inner hole of the temperature probe 3. If the gap is too large, the thermal response time will be increased. If the gap is too small, the platinum resistor will touch the metal shell, thereby reducing its adaptability to mechanical environments. The design of the present invention adopts a gap between 0.25mm and 0.3mm, which improves the process assemblability of the product while ensuring the product response time.

[0028] The filling material is mainly used to fill the gap between the platinum resistor 1 and the temperature probe 3 after they are assembled. The thermal conductivity of the filling material has a great influence on the response time of the sensor. Therefore, the selection of the filling material and the filling process are crucial to improving the response time of the sensor.

[0029] This embodiment uses conductive silver paste 2 as the filling material for filling, and its thermal conductivity is 60-90 W / mk, which is better than the thermal conductivity of thermal conductive glue, which is generally 2-4 W / mk. After the filling of the conductive silver paste 2 is completed, sintering is performed to ensure the density of the filling material and effectively reduce the impact of impurities such as air and water vapor on heat transfer.

[0030] The filling process adopted in this embodiment is: the conductive silver paste 2 is filled into the inner hole of the temperature probe 3 by vacuum filling, the platinum resistor 1 is installed into the inner hole of the temperature probe 3, vacuum degassing, standing, vacuum degassing treatment, and finally curing and sintering. Wherein:

[0031] It must be filled from the bottom to ensure that no air is introduced during the filling process, and through the vacuum degassing, standing and vacuum degassing process, ensure that there is no air in the conductive silver paste.

[0032] Filling dosage control uses precision filling equipment for filling to ensure that the filling dosage does not exceed the insulation layer of the platinum resistor 1. Multiple filling methods can be used.

[0033] Curing temperature: The sintering temperature is strictly controlled according to the sintering characteristic curve of the material, and exhaust treatment is carried out during the sintering process to ensure that there will be no cracking during the sintering process.

[0034] See also Figure 4 The temperature of the medium is sensed by the temperature probe 3, and the temperature is transmitted to the platinum resistor 1 through the conductive silver paste 2. The platinum resistor 1 generates a resistance signal that changes with the temperature, which is sent to the connector 5 through the wire and outputs a resistance signal proportional to the measured temperature.

Claims

1. A fast-response temperature sensor based on sintering of conductive silver paste, characterized in that: The fast-response temperature sensor has a temperature probe (3) sealed and welded at the front end of a mounting seat (4), and a connector (5) sealed and welded at the rear end of the mounting seat (4); a platinum resistor (1) is sealed in the inner cavity of the temperature probe (3) by sintering a conductive silver paste (2); the cross-sectional shape of the temperature probe (3) and the platinum resistor (1) are the same, the gap between the two is between 0.25 mm and 0.3 mm, and the gap size between the platinum resistor (1) and the temperature probe (3) in the transverse direction is smaller than the gap size in the axial direction; the platinum resistor (1) is connected to the connector (5) via a wire.

2. The fast response temperature sensor according to claim 1, characterized in that: The mounting seat (4) and the temperature probe (3) are fixed by laser welding.

3. The fast response temperature sensor according to claim 1, characterized in that: The mounting seat (4) and the connector (5) are fixed by laser welding.

4. The fast response temperature sensor according to claim 1, characterized in that: The cross-sections of the temperature probe (3) and the platinum resistor (1) are rectangular.

5. The fast response temperature sensor according to claim 1, characterized in that: The cross sections of the temperature probe (3) and the platinum resistor (1) are circular.

6. The fast response temperature sensor according to any one of claims 1 to 5, characterized in that: In the sintering process, the conductive silver paste (2) is filled into the inner hole of the temperature probe (3) by vacuum filling, and then the platinum resistor (1) is installed in the inner hole of the temperature probe (3) and immersed in the conductive silver paste (2), and then vacuum degassing, standing, vacuum degassing treatment, and finally curing and sintering are performed.

7. The fast response temperature sensor according to claim 6, characterized in that: Start filling from the bottom.

8. The fast response temperature sensor according to claim 7, characterized in that: Use multiple filling.

9. The fast response temperature sensor according to claim 6, characterized in that: The sintering temperature is strictly controlled according to the material sintering characteristic curve.

Images