Preparation method of thin film thermocouple based on thermal insulation layer and thin film thermocouple

Abstract

The invention discloses a preparation method of a thin film thermocouple based on a thermal insulation layer and the thin film thermocouple, and the method comprises the steps: making an insulating bottom layer thin film through an insulating material, cutting the thin film into a round sample wafer, and carrying out the ultrasonic cleaning; fixing a first mask plate on the thin film sample wafer, and forming a positive electrode of a thermocouple through magnetron sputtering; fixing a second mask plate on the thin film sample wafer, forming a negative electrode of the thermocouple through magnetron sputtering, and forming a thermocouple node at the overlapped end part; plating or bonding a protective layer on the surface of the film sample according to the requirement of a detected environment; cutting the thin film thermocouples from the thin film sample, and fixedly connecting positive and negative electrode leads to the positive and negative electrodes of each thin film thermocouple through bonding or welding; aerogel is adopted as a heat insulation layer and is adhered to the thin film thermocouple through a cementing process to form the thin film thermocouple based on the heat insulation layer. The temperature measuring accuracy of the thermocouple can be improved, and the thermocouple can be suitable for occasions with complex environments.

Description

Technical Field

[0001] The invention belongs to the field of surface temperature measurement, and in particular relates to a preparation method of a thin film thermocouple based on a thermal insulation layer and the thin film thermocouple. Background Art

[0002] The surface temperature of an object is an important parameter that reflects the surface state of the object. Thin-film thermocouples have the advantages of small heat capacity, high sensitivity, fast response time, and little interference with the original environment of the object being measured. They are widely used in the field of surface transient temperature measurement. At present, thin-film thermocouples are mainly pasted on the surface of the object being measured through a gluing process, and the surface temperature of the object is reflected by the change of thermoelectric potential. However, in the actual measurement process, as the ambient temperature changes, the surface temperature of the object being measured also changes due to the existence of radiation errors, which directly affects the temperature measurement accuracy of thin-film thermocouples. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a thin film thermocouple based on a thermal insulation layer and a thin film thermocouple to address the problem that the surrounding environment affects the surface temperature measurement of the object being measured due to the existence of radiation error, which can improve the temperature measurement accuracy of the thermocouple.

[0004] In order to achieve the above object, one aspect of the present invention provides a method for preparing a thin film thermocouple based on a thermal insulation layer, comprising:

[0005] Step S1, using insulating material to make an insulating bottom film, cutting the film into circular samples and cleaning them with ultrasound;

[0006] Step S2, fixing a circular first mask plate on the thin film sample, the first mask plate being provided with a plurality of first linear patterns, and placing the first mask plate in a magnetron sputtering device for magnetron sputtering, thereby forming a positive electrode of a thermocouple on the surface of the thin film sample;

[0007] Step S3, fixing a circular second mask plate on the thin film sample, on which a plurality of second linear patterns are arranged, so that the first linear pattern and the second linear pattern overlap at the ends, placing the thin film sample in a magnetron sputtering device for magnetron sputtering, thereby forming a negative electrode of a thermocouple on the surface of the thin film sample, and the overlapping ends form a thermocouple junction;

[0008] Step S4, plating or bonding a protective layer on the surface of the thin film sample according to the requirements of the measured environment to obtain a plurality of thin film thermocouples on the thin film sample;

[0009] Step S5, cutting the thin film thermocouple from the thin film sample, and fixing the positive and negative electrode leads at the positive and negative electrodes of each thin film thermocouple by bonding or welding;

[0010] Step S6, using aerogel as a heat insulation layer, and pasting it on the thin film thermocouple through a gluing process to form a thin film thermocouple based on the heat insulation layer.

[0011] Preferably, ceramic, sapphire or polyimide film is selected to make the insulating bottom film, and the thickness of the insulating bottom film is 0.1 mm to 5 mm.

[0012] Preferably, a polyimide film with a thickness of 0.1 mm is selected to make the insulating bottom film.

[0013] Preferably, a NiCr alloy target is used to form the first linear pattern, and a NiSi alloy target is used to form the second linear pattern, and the sputtering power is not greater than 100 W, the sputtering time is not more than 1 hour, and the vacuum degree is not greater than 10 -4 The magnetron sputtering was carried out under the condition of Pa.

[0014] Preferably, when the measured environment is a low-temperature environment, a polyimide protective layer is bonded on the surface of the sensitive layer, and when the measured environment is a high-temperature environment or a metal medium is tested, an Al2O3 protective layer is plated on the surface of the sensitive layer.

[0015] Preferably, the lead wire is made of a thermocouple compensation wire having a graduation consistent with that of a thin film thermocouple.

[0016] Preferably, aerogel with a thermal conductivity of no more than 0.02 W / (m·K) is used as the heat insulation layer.

[0017] Preferably, a step is provided at the bottom of the aerogel for bonding the lead wires so that the lead wire bonding position is kept level with the plane of the thin film thermocouple.

[0018] Another aspect of the present invention provides a thin film thermocouple based on a thermal insulation layer, characterized in that it is prepared by the above method.

[0019] According to the method for preparing a thin-film thermocouple based on a heat-insulating layer and the thin-film thermocouple of the above aspects of the present invention, the temperature measurement accuracy of the thermocouple can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0021] Figure 1 It is a flow chart of a method for preparing a thin film thermocouple based on a thermal insulation layer according to an embodiment of the present invention;

[0022] Figure 2is a schematic diagram of a first mask plate and a second mask plate according to an embodiment of the present invention;

[0023] Figure 3 It is a schematic structural diagram of a thin film thermocouple based on a thermal insulation layer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The embodiment of the present invention provides a method for preparing a thin film thermocouple based on a thermal insulation layer, such as Figure 1 As shown, the method for preparing a thin film thermocouple based on a thermal insulation layer according to an embodiment of the present invention includes steps S1 to S6.

[0026] In step S1, an insulating bottom film is made. The insulating bottom film can be made of insulating materials such as ceramic, sapphire or polyimide film. The thickness range can be determined according to the measured temperature range, generally 0.1mm-5mm. In one embodiment, a polyimide film with a thickness of 0.1mm is selected to make the insulating bottom film, and the film is cut into circular samples, and the samples are cleaned with ultrasound to prevent surface impurities from affecting the plating effect.

[0027] Step S2, making a sensitive layer. Fix the following on the film sample: Figure 2 The circular first mask plate shown in (a) is provided with a plurality of first linear patterns, thereby increasing the number of thermocouples in a single sputtering. The film sample with the first mask plate fixed is placed in a magnetron sputtering device for magnetron sputtering, so that the positive electrode of the thermocouple is formed on the surface of the film sample.

[0028] The sensitive layer can use different thermocouple materials or semiconductor materials as temperature sensing elements according to the different temperatures to be measured. In one embodiment, a K-type thermocouple is used as the sensitive element, and a NiCr alloy target is selected to form a first linear pattern. The film sample with the first mask fixed is placed in the plating area of ​​a magnetron sputtering device, and the sputtering power is not more than 100W (for example, 90W), the sputtering time is not more than 1 hour (for example, 40 minutes), and the vacuum degree is not more than 10 -4 Pa was magnetron sputtered to form NiCr linear shapes on the surface of the film sample, which formed the positive electrode of the thermocouple.

[0029] In step S3, Figure 2The circular second mask plate shown in (b) is fixed on the thin film sample, and a plurality of first linear patterns are arranged on the second mask plate to ensure that the ends of the first linear patterns and the second linear patterns overlap. The second mask plate is placed in a magnetron sputtering device for magnetron sputtering, thereby forming a negative pole of the thermocouple on the surface of the thin film sample, and a thermocouple junction is formed at the overlapping ends of the positive pole and the negative pole.

[0030] In one embodiment, in the case of a K-type thermocouple, a NiSi alloy target is selected to form a second linear pattern, and a second mask is fixed on the thin film sample to ensure that the two linear patterns overlap at the ends. Magnetron sputtering is performed to form NiSi linear patterns on the surface of the thin film sample. At this time, the two linear patterns form thermocouple junctions at the ends.

[0031] In step S4, in order to prevent the sensitive layer from being oxidized and reduce the impact of the sensitive layer on the harsh environment, a protective layer is plated or bonded on the surface of the sensitive layer according to the requirements of the tested environment to obtain multiple thin film thermocouples on the thin film sample. In a low temperature environment, a polyimide protective layer can be directly bonded, and in a high temperature environment or an environment where a metal medium is tested, an Al2O3 protective layer is made. In the process of making the protective layer, avoid the lead position of the thin film thermocouple.

[0032] In step S5, the thin film thermocouple is cut from the thin film sample, and the positive and negative electrode leads are fixed to each thermocouple. The leads are fixedly connected to the positive and negative electrodes of the thermocouple by bonding or welding. The leads are made of thermocouple compensation wires that are consistent with the thermocouple graduation. In the case of bonding, the positive and negative electrode leads are respectively bonded and fixed with conductive glue, and the thermocouple is placed in a high temperature furnace at 100°C to dry the conductive glue for 1 hour.

[0033] In step S6, an aerogel with a thermal conductivity of no more than 0.02W / (m·K) is used as a thermal insulation layer and is bonded to the thermocouple through a gluing process, thereby reducing the impact of the surrounding environment on the thermocouple sensor. In one embodiment, an aerogel with a thermal conductivity of 0.015W / (m·K) is used as the thermal insulation layer. In addition, in order to keep the lead bonding position level with the plane of the thin film thermocouple in the later stage, a step with a width of 5mm and a height of 5mm is designed at the bottom of the aerogel. At this point, the preparation of the thin film thermocouple based on the thermal insulation layer is completed, and Figure 3 The thin film thermocouple shown includes an insulating base layer 1, a sensitive layer 2, a protective layer 3, a heat insulation layer 4 and a lead wire 5.

[0034] The method for preparing a thin film thermocouple based on a thermal insulation layer of this embodiment has the following beneficial effects: by introducing aerogel as the thermal insulation layer of the thin film thermocouple, the structure of the thin film thermocouple is improved and the temperature measurement accuracy is improved. In addition, this structure reduces the influence of the surrounding environment on the surface temperature measurement of the object to be measured due to the existence of radiation errors, and can be applied to occasions with complex environments.

[0035] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a thin film thermocouple based on a thermal insulation layer, characterized in that: include: Step S1, using insulating material to make an insulating bottom film, cutting the film into circular samples and cleaning them with ultrasound; Step S2, fixing a circular first mask plate on the thin film sample, the first mask plate being provided with a plurality of first linear patterns, and placing the first mask plate in a magnetron sputtering device for magnetron sputtering, thereby forming a positive electrode of a thermocouple on the surface of the thin film sample; Step S3, fixing a circular second mask plate on the thin film sample, on which a plurality of second linear patterns are arranged, so that the first linear pattern and the second linear pattern overlap at the ends, placing the thin film sample in a magnetron sputtering device for magnetron sputtering, thereby forming a negative electrode of a thermocouple on the surface of the thin film sample, and the overlapping ends form a thermocouple junction; Step S4, plating or bonding a protective layer on the surface of the thin film sample according to the requirements of the measured environment to obtain a plurality of thin film thermocouples on the thin film sample; Step S5, cutting the thin film thermocouple from the thin film sample, and fixing the positive and negative electrode leads at the positive and negative electrodes of each thin film thermocouple by bonding or welding; Step S6, using aerogel as a heat insulation layer, and pasting it on the thin film thermocouple through a gluing process to form a thin film thermocouple based on the heat insulation layer.

2. The method according to claim 1, characterized in that The insulating bottom film is made of ceramic, sapphire or polyimide film, and the thickness of the insulating bottom film is 0.1mm to 5mm.

3. The method according to claim 2, characterized in that A polyimide film with a thickness of 0.1 mm is selected to make the insulating bottom film.

4. The method according to any one of claims 1 to 3, characterized in that A NiCr alloy target is used to form the first linear pattern, and a NiSi alloy target is used to form the second linear pattern. The sputtering power is not more than 100W, the sputtering time is not more than 1 hour, and the vacuum degree is not more than 10 -4 The magnetron sputtering was carried out under the condition of Pa.

5. The method according to any one of claims 1 to 3, characterized in that: When the measured environment is a low-temperature environment, a polyimide protective layer is bonded on the surface of the sensitive layer. When the measured environment is a high-temperature environment or a metal medium is tested, an Al2O3 protective layer is plated on the surface of the sensitive layer.

6. The method according to any one of claims 1 to 3, characterized in that The lead wire is made of a thermocouple compensation wire with the same graduation as the film thermocouple.

7. The method according to any one of claims 1 to 3, characterized in that Aerogel with a thermal conductivity of no more than 0.02 W / (m·K) is used as the heat insulation layer.

8. The method according to any one of claims 1 to 3, characterized in that A step is provided at the bottom of the aerogel for bonding the lead wire so that the lead wire bonding position is kept level with the plane of the thin film thermocouple.

9. A thin film thermocouple based on a thermal insulation layer, characterized in that: It is prepared by the method according to any one of claims 1 to 8.

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