Electricity-substituted planar radiation measurement detector and preparation method thereof

Abstract

The present invention relates to the technical field of radiation measurement, and particularly to an electrical substitution planar radiation measurement detector. The electrical substitution planar radiation measurement detector includes a substrate, and the substrate includes an upper surface and a lower surface; a heating wire is provided on the upper surface, and a thermopile is provided on the lower surface; a via hole is further provided on the electrical substitution planar radiation measurement detector, and the heating wire is led to the lower surface through the via hole. The present invention uses microfabrication technology to fabricate an electrically heated wire on the upper surface of the planar detector substrate and a thermopile on the lower surface. Similar to the measurement principle of the cavity-type detector, electrical substitution measurement is carried out through the planar detector, which can ignore the change of ambient temperature and ensure a certain measurement accuracy within a relatively wide measurement temperature range.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation measurement, and in particular to an electrically substituted planar radiation measurement detector and a preparation method thereof. Background Art

[0002] Solar radiation is the main external energy source of the earth. By precisely measuring the Total Solar Irradiance (TSI), the slight changes in solar radiation can be used to predict the changes in the earth's climate, which has good guiding significance for agricultural meteorology and marine meteorology.

[0003] At present, high-precision radiation measurement and metrology worldwide mainly use cavity-type electrically substituted absolute radiometers. The core detector is a blackbody cavity, where the optical power is reflected and absorbed multiple times in the blackbody cavity, resulting in a new equilibrium state of the cavity temperature. Based on the measurement principle of electrical substitution, the change in cavity temperature generated by the optical power is reproduced by electrical power, and the unknown optical power can be obtained through the accurately measured equivalent electrical power. The measurement result can be directly traced back to the current in the International System of Units (SI). Currently, the DIARADs-type absolute radiometer of the Royal Belgian Institute, the TIM of the National Aeronautics and Space Administration (NIST) of the United States, the PMO6 of the World Radiation Center in Switzerland, and the Total Solar Irradiance Monitor (TSIM) independently developed in China all use this cavity-type electrically substituted radiometer.

[0004] The advantages of the cavity-type electrically substituted detector are high measurement accuracy, and it is currently the radiation meter with the highest accuracy at room temperature in the world. However, its disadvantages are also obvious. First, the manufacturing process is very complex, resulting in a high cost. Second, the volume is relatively large. At the same time, in order to reduce the influence of the electro-optical non-equivalence, silver with a relatively large thermal conductivity is used, and the heat capacity of the overall cavity is relatively large, resulting in a long measurement time. Third, limited by the structural form, it can only be used to measure direct solar radiation, and total radiation, scattered radiation, and long-wave radiation cannot use the cavity-type electrically substituted detector.

[0005] Due to these disadvantages, the cavity-type electrically substituted detector is not suitable for the measurement of ground total radiation, scattered radiation, long-wave radiation, etc. Because different from direct space radiation, total radiation may suddenly change in a short time, and a relatively long measurement time will lead to inaccurate measurement during sudden changes. The used planar detector. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides an electrically substituted planar radiation measurement detector with a new structure, and further solves the problem that the existing planar detector cannot perform electrically substituted radiation measurement.

[0007] The electric substitution planar radiation measurement detector provided by the present invention includes a substrate, and the substrate includes an upper surface and a lower surface; a heating wire is provided on the upper surface, and a thermopile is provided on the lower surface; a via hole is further provided on the electric substitution planar radiation measurement detector, and the heating wire is led to the lower surface through the via hole.

[0008] Preferably, the material of the substrate is silicon nitride ceramic material.

[0009] Preferably, the thermopile is a three-layer structure.

[0010] Preferably, the heating wire completely covers the upper surface.

[0011] Preferably, the material of the heating wire is constantan wire, pure copper wire, nickel-chromium wire or iron-chromium-aluminum wire.

[0012] Preferably, the width of the heating wire is 1 mm, the thickness of the heating wire is 20 nm, and the total resistance of the heating wire is 1000 ohms.

[0013] Preferably, a light absorption material is provided on the upper surface.

[0014] Preferably, the light absorption material is gold black.

[0015] Preferably, a lead pad is further provided on the lower surface, and the lead pad includes an upper lead pad and a lower lead pad.

[0016] On the other hand, the present invention also provides a preparation method of the above-mentioned electric substitution planar radiation measurement detector, and the preparation method includes the steps:

[0017] S1. Cut out the shape of the substrate according to the design value, and polish the upper surface and the lower surface to a roughness better than 20 nm;

[0018] S2. Make a via hole according to the structural design of the electric substitution planar radiation measurement detector;

[0019] S3. Make the heating wire on the upper surface through a microfabrication process, and lead the heating wire to the lower surface through the via hole; make the thermopile on the lower surface through a microfabrication process.

[0020] The electric substitution planar radiation measurement detector and its preparation method of the present invention creatively adopt a microfabrication process to make an electric heating wire on the upper surface of the planar detector substrate and a thermopile on the lower surface. Similar to the measurement principle of the cavity-type detector, through the planar detector for electric substitution measurement, the change of the ambient temperature can be ignored, and a certain measurement accuracy can be guaranteed within a relatively wide measurement temperature range. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0022] Figure 2 It is a schematic structural diagram of a heating wire in an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0023] Figure 3 It is a thermal analysis steady-state result diagram of applying optical power to an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0024] Figure 4 It is a simulation curve diagram of applying optical power to an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0025] Figure 5 It is a thermal analysis steady-state result diagram of applying electrical power to an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0026] Figure 6 It is a simulation curve diagram of applying electrical power to an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0027] Figure 7 It is a schematic diagram of the coverage area of a heating wire in an electrical substitution planar radiation measurement detector according to an embodiment of the present invention.

[0028] Reference numerals:

[0029] Substrate 1, lower surface 2, upper lead pad 3, lower lead pad 4, thermopile 5, heating wire 6, upper surface 7, lead pad 8. Detailed implementation manners

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0031] As Figure 1 and Figure 2As shown, it is a schematic structural diagram of an electrical substitution planar radiation measurement detector according to an embodiment of the present invention. It can be seen from the figure that the electrical substitution planar radiation measurement detector provided by the specific embodiment of the present invention includes a substrate 1, and the substrate 1 includes an upper surface 7 and a lower surface 2; specifically, the upper surface 7 is the front surface of the electrical substitution planar radiation measurement detector, and the lower surface 2 is the back surface of the electrical substitution planar radiation measurement detector; a heating wire 6 is provided on the upper surface 7, and a thermopile 5 is provided on the lower surface 2; a via hole is also provided on the electrical substitution planar radiation measurement detector, and the heating wire 6 is led to the lower surface 2 through the via hole. Specifically, there is no requirement for the size of the via hole provided on the electrical substitution planar radiation measurement detector, as long as it can ensure conductivity, and it can be processed according to the standard size of the circuit board.

[0032] In a specific embodiment, the material of the substrate 1 is a silicon nitride ceramic material. The outer shape of the substrate 1 is cut according to the design value, and the upper surface 7 and the lower surface 2, these two upper and lower planes, are polished to facilitate the subsequent production of the thermopile 5 and the heating wire 6 respectively. The thermopile 5 is composed of multiple pairs of thermocouples. In a preferred embodiment, the thermopile 5 is a three-layer structure to increase the number of thermocouples and thus increase the sensitivity; specifically, the thermopile 5 can include 300 pairs of thermocouples. After specific polishing, the roughness of the upper surface 7 and the lower surface 2 is at least better than 20 nm, so that it is not easy to break when electroplating the heating wire and the thermocouple on the upper surface and the lower surface respectively. By leading the heating wire 6 made on the upper surface 7 to the lower surface 2 through the via hole, the flatness of the upper surface 7 can be better ensured, so that the field of view angle of the electrical substitution planar radiation measurement detector of the present invention can reach 2π, which is convenient for the accurate measurement of total radiation and scattered radiation.

[0033] In a specific embodiment, as Figure 2 shown, the heating wire 6 is an electric heating wire, and its material can be selected from constantan, pure copper, nickel-chromium, iron-chromium-aluminum, etc. Specifically, it can be selected according to the resistivity and the requirements of the manufacturing process. By using constantan wire to make the heating wire 6 on the upper surface 7, the heating wire 6 completely covers the entire upper surface 7 to reduce the photoelectric non-equivalence. In this embodiment, the width of the heating wire 6 is 1 mm, the thickness of the heating wire 6 is 20 nm, and the total resistance of the heating wire 6 is 1000 ohms. Specifically, the total resistance of the heating wire 6 can be determined according to the irradiation magnitude of the measurement target and the magnitude of the applied voltage. Through the magnitude of the total resistance requirement, the width, thickness and length of the heating wire 6 are then set.

[0034] In a specific embodiment, as Figure 1As shown, a lead pad is further provided on the lower surface 2. The lead pad includes an upper lead pad 3 and a lower lead pad 4. The heating wire 6 is led to the lower surface 2 through the via hole, and the upper lead pad 3 is formed on the lower surface 2 to ensure the flatness of the upper surface 7. In addition, the lead pads of the thermopile 5 provided on the lower surface 2 are also provided on the lower surface 2, that is, the lower lead pads 4. Through the two upper lead pads 3 and the two lower lead pads 4, the external power connection wires of the electrical substitution planar radiation measurement detector can be better imitated.

[0035] In a preferred embodiment, after the thermopile 5, the heating wire 6, and the lead pad 3 are respectively fabricated on the upper surface and the lower surface of the substrate 1, a light absorption material is provided on the upper surface of the detector by spraying or growing. The light absorption rate of the light absorption material is not less than 95%. Further preferably, the light absorption material can be gold black, etc. By setting gold black, the measurement accuracy can be improved by increasing the absorption rate. At the same time, it also has the ability to resist degradation.

[0036] On the other hand, in the specific embodiment of the present invention, a preparation method of the above electrical substitution planar radiation measurement detector is further provided. The preparation method includes the steps:

[0037] S1. Cut out the outer shape of the substrate 1 according to the design value, and polish the upper surface 7 and the lower surface 2 to a roughness better than 20 nm to ensure the flatness of the two surfaces. Specifically, the substrate 1 is made of a ceramic material, and the outer shape of the substrate 1 is fabricated by a laser cutting process. The specific design value can be determined according to the mechanical properties, sensitivity requirements, and the number of thermocouple pairs required for the electrical substitution planar radiation measurement detector.

[0038] S2. Fabricate vias according to the structural design of the electrical substitution planar radiation measurement detector. Specifically, a powerful laser can be used to fabricate vias. The position of the vias is close to the edge of the substrate 1. Preferably, the distance from the edge of the substrate 1 is 0.5 mm to better ensure the stiffness of the vias.

[0039] S3. Fabricate the heating wire 6 on the upper surface 7 through a microfabrication process. The heating wire 6 is led to the lower surface 2 through the via hole. Fabricate the thermopile 5 on the lower surface 2 through a microfabrication process. The description of this step does not limit the order of fabricating the heating wire 6 on the upper surface 7 and fabricating the thermopile 5 on the lower surface 2. Specifically, after the number of thermocouple pairs is designed according to the design value, a layer of constantan is sputtered on the lower surface 2 of the detector substrate 1. According to the design three-dimensional diagram as Figure 1 shown, the redundant parts are etched away, and only 300 pairs of thermocouples shown in the figure are retained. Then, pure copper is electroplated on the surface of half of the constantan wire according to the thermocouple measurement mechanism, and finally the pads are fabricated to complete the fabrication of the thermopile 5.

[0040] The electric substitution planar radiation measurement detector and its preparation method of the present invention creatively use microfabrication technology to fabricate an electric heating wire on the upper surface of the planar detector substrate and a thermopile on the lower surface. Similar to the measurement principle of the cavity detector, through the electric substitution measurement of the planar radiation measurement detector, the change of the ambient temperature can be ignored, and a certain measurement accuracy can be guaranteed within a relatively wide measurement temperature range.

[0041] Performance test

[0042] For the electric substitution planar radiation measurement detector provided in the embodiment of the present invention, detailed analysis is carried out using the finite element analysis software COMSOL. The sensitivity of the detector designed in the embodiment of the present invention can reach 14 μV / (W·m -2 ), and the 95% response time is less than 4 s, which fully meets the measurement requirements of the secondary radiation meter formulated by the meteorological bureau for sensitivity and response time.

[0043] The simulation analysis method is used to verify the measurement ability of the electric substitution planar radiation measurement detector provided by the present invention. Specifically, in the simulation analysis, a heat flux power of 1000 W·m -2 is applied to the upper surface of the electric substitution planar radiation measurement detector provided by the present invention to simulate the total radiation intensity, and the purpose is to obtain the sensitivity, response time of the designed detector, and the magnitude of the photoelectric non-equivalence during the electric substitution radiation measurement.

[0044] (1) Stable ambient temperature

[0045] First, when considering that the ambient temperature remains unchanged (293.15 K), the output of the temperature difference of the detector is examined, and the response time can be calculated at the same time. The input conditions for the simulation analysis are: the cold point is the constant ambient temperature, and a heat flux power of 1000 W·m -2 is applied to the upper surface of the detector. The measurement parameters adopt the thermophysical parameters of the actual substrate silicon nitride ceramic material. Since this material can be directly commercially available, the relevant parameters can be obtained from the manufacturer.

[0046] The steady-state result diagram and the simulation curve diagram of the thermal analysis for applying optical power to the electric substitution planar radiation measurement detector provided in the embodiment of the present invention are respectively as Figure 3 Figure 4 shown. The ordinate in the figure is the temperature value, with the unit K, and the other two coordinates are both dimension values, with the unit m; the five curves from top to bottom in the figure respectively represent the comprehensive temperature difference, the temperature of side probe 1, the temperature of side probe 2, the temperature of side probe 3, and the temperature of side probe 4. Among them, side probe 1, side probe 2, and side probe 3 respectively represent Figure 1The temperature of the hot spot of the thermopile 5 with the three-layer structure from the inside out shown in the figure, while the edge probe 4 represents the temperature of the cold spot of the detector; it can be seen from the figure that through processing, the 95% response time of the detector is about 3.5 s; the sensitivity of the detector is calculated by the following formula:

[0047] s = n*S k *ΔT / P

[0048] where n is the number of thermocouple pairs, S k is the Seebeck coefficient, ΔT is the temperature difference, and P is the light irradiance.

[0049] After calculation, the sensitivity of the electrical substitution planar radiation measurement detector provided in the inventive embodiment is about 14 μV / (W·m -2 ).

[0050] (2) Simulation analysis of electrical substitution measurement

[0051] In order to further verify the measurement ability and measurement effect of the electrical substitution planar radiation measurement detector provided by the present invention, simulation analysis is carried out according to the actual situation. Apply the heat flux power density of the optical power magnitude before equivalence to the electric heating wire, compare the analysis results with the previous ones, and calculate the difference between the electrical power measurement and the optical power measurement.

[0052] The steady-state thermal analysis result diagram and simulation curve diagram of applying electrical power to the electrical substitution planar radiation measurement detector provided in the inventive embodiment are respectively as Figure 5 Figure 6 shown. The ordinate in the figure is the temperature value, with the unit K, and the other two coordinates are both dimension values, with the unit m; the five curves from top to bottom in the figure respectively represent the temperature of edge probe 1, the comprehensive temperature difference, the temperature of edge probe 2, the temperature of edge probe 3, and the temperature of edge probe 4; similarly, edge probe 1, edge probe 2, and edge probe 3 respectively represent Figure 1 the temperature of the hot spot of the thermopile 5 with the three-layer structure from the inside out shown in the figure, while edge probe 4 represents the temperature of the cold spot of the detector, and the comprehensive temperature difference refers to the weighted average temperature difference between the three hot spots and the cold spot, and the weight is the number of thermocouple pairs in each layer; it can be seen from the figure that by comparing the simulation results and through calculation, the difference between the output temperature differences of applying electrical power and applying optical power to the detector designed by the present invention is less than 0.5%, and the photoelectric non-equivalence quantity value is relatively small, which can be used for electrical substitution radiation measurement.

[0053] In other embodiments, according to different measurement targets, the production area of the heating wire 6 can be changed. For example, when measuring direct radiation, there will be a precision aperture in front of the detector, so the production area of the heating wire 6 should be equal to the area of the precision aperture; as Figure 7As shown, the area of the middle heating wire 6 represents the heating wire with the same area as the diaphragm, and the blank area is the upper surface 7 of the detector substrate. In addition, it can be seen that the lead pads 8 are made under the detector for facilitating wire soldering.

[0054] The electric substitution planar radiation measurement detector and its preparation method of the present invention can be used not only for electric substitution measurement but also for the measurement of radiation power meters and radiation heat flux meters.

[0055] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0056] The above specific implementation manners of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An electric substitution planar radiation measurement detector, characterized in that The electric substitution planar radiation measurement detector includes a substrate made of silicon nitride ceramic material, the substrate including an upper surface and a lower surface; a heating wire is provided on the upper surface, and a thermopile is provided on the lower surface, the thermopile being composed of multiple pairs of thermocouples; The electric substitution planar radiation measurement detector is further provided with a via hole, and the heating wire is led to the lower surface through the via hole; The lower surface is further provided with lead pads, the lead pads including upper lead pads and lower lead pads.

2. The electric substitution planar radiation measurement detector according to claim 1, characterized in that, The thermopile is a three-layer structure.

3. The planar radiation measurement detector with electrical substitution as claimed in claim 1, wherein The heating wire completely covers the upper surface.

4. The electrical substitution planar radiation measurement detector according to claim 1, characterized in that, The material of the heating wire is constantan wire, pure copper wire, nichrome wire or FeCrAl wire.

5. The electrical substitution planar radiation measurement detector according to claim 1, characterized in that, The width of the heating wire is 1 mm, the thickness of the heating wire is 20 nm, and the total resistance of the heating wire is 1000 ohms.

6. The electrical substitution planar radiation measurement detector according to claim 1, characterized in that, A light absorption material is provided on the upper surface.

7. The electric substitution planar radiation measurement detector according to claim 6, wherein The light absorption material is gold black.

8. The preparation method of the electrical substitution planar radiation measurement detector according to any one of claims 1 to 7, characterized in that The preparation method includes the steps: S1. Cut out the shape of the substrate according to the design value, and polish the upper surface and the lower surface to a roughness better than 20 nm; the material of the substrate is silicon nitride ceramic material; S2. Fabricate the via hole according to the structural design of the electric substitution planar radiation measurement detector; S3. Fabricate the heating wire on the upper surface through a microfabrication process, lead the heating wire to the lower surface through the via hole, and form upper lead pads on the lower surface; fabricate the thermopile on the lower surface through a microfabrication process; The process of fabricating the thermopile is as follows: sputter a layer of constantan on the lower surface of the substrate, etch away the redundant parts, only leaving the remaining thermocouples, then electroplate pure copper on the surface of half of the constantan wire according to the thermocouple measurement mechanism, and finally fabricate the lower lead pads to complete the fabrication of the thermopile.

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