Gas sensor and manufacturing method thereof

Abstract

A gas sensor and a manufacturing method thereof belong to the technical field of sensors. In order to solve the problems of large volume, high energy consumption, low sensitivity, complex manufacturing process and the like of the traditional gas sensor, the method comprises the following steps: performing electrolytic oxidation material increase on the basic shape of a chip substrate to obtain a primary chip substrate; then photoresist is smeared on the corresponding positions of the bottom heat insulation groove and the top heat insulation groove, and photosensitive curing is carried out; carrying out electrolytic oxidation material adding again, and then removing the photoresist to obtain a chip substrate with a bottom heat insulation groove and a top heat insulation groove; generating a signal electrode, a reference electrode and an electrode bonding pad which are composed of platinum films by using a magnetron sputtering film forming technology; preparing an aluminum nitrate doped noble metal catalyst into slurry, uniformly stirring and mixing, completely covering a signal electrode area and a reference electrode area, then drying and calcining at high temperature to obtain a primary sensor core body, spraying a desensitizer, and then calcining at high temperature to obtain a sensor core body; and packaging with a packaging shell to obtain the gas sensor.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a gas sensor and a manufacturing method thereof. Background Art

[0002] As a new generation of clean energy, hydrogen and cars powered by hydrogen fuel cells are the focus of future new energy development. Hydrogen itself is flammable and explosive, and is in gaseous form at room temperature. High-pressure containers are often required for transportation. At the same time, the radius of hydrogen atoms is small, and it is easy to diffuse into the gaps between metal atoms, resulting in weakened binding forces between metal atoms and brittle fracture. These factors make hydrogen difficult to transport and store, while ammonia has a low ignition point, stable storage properties, and high hydrogen content, making it one of the medium options for hydrogen transportation and storage. In the process of hydrogen to ammonia transmission and storage, ammonia and hydrogen leakage will inevitably occur. Gas sensors are required to monitor ammonia and hydrogen concentrations in real time. Traditional gas sensors are large in size and have low sensitivity. In addition, since gas sensors often need to work properly in a high-temperature environment, traditional gas sensor cores dissipate heat quickly and consume high energy. The manufacture of traditional gas sensors also often involves subtractive manufacturing processes such as cutting and chemical etching, which is relatively complicated. Summary of the invention

[0003] The problem to be solved by the present invention is to solve the problems of large size, high energy consumption, low sensitivity and complex manufacturing process of traditional gas sensors, and propose a gas sensor and a manufacturing method thereof.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for manufacturing a gas sensor comprises the following steps:

[0006] Step 1: Cut the high-purity aluminum foil according to the size of the chip substrate to obtain the basic shape of the chip substrate;

[0007] Step 2: Place the basic shape of the chip substrate into an electrolytic device, add boric acid as an electrolyte for electrolytic oxidation and material addition, grow porous γ-Al2O3 material on the basic shape of the chip substrate, and obtain a preliminary chip substrate;

[0008] Step 3, soaking the preliminary chip substrate in a chromic acid phosphate solution at room temperature to obtain a soaked preliminary chip substrate, then applying photoresist to the corresponding positions of the bottom insulation groove and the top insulation groove, and then covering the preliminary chip substrate coated with the photoresist with a photoresist plate to perform photosensitive curing;

[0009] Step 4: Place the preliminary chip substrate after photosensitive curing into an electrolytic device, add boric acid as an electrolyte to perform electrolytic oxidation and material addition, and then remove the photoresist to obtain a chip substrate with a bottom insulation groove and a top insulation groove;

[0010] Step 5: On the upper surface of the chip substrate having the bottom heat insulation groove and the top heat insulation groove, a signal electrode, a reference electrode and an electrode pad composed of a platinum film are formed by using a magnetron sputtering film forming technology;

[0011] Step 6: doping aluminum nitrate with a noble metal catalyst, mixing the doped powder with a binder into a slurry, stirring and mixing evenly, completely covering the signal electrode area and the reference electrode area, and then drying and calcining at a high temperature to obtain a preliminary sensor core;

[0012] Step 7: spraying a desensitizer on the reference electrode area of ​​the preliminary sensor core, and then calcining at high temperature to obtain the sensor core;

[0013] Step 8: Weld the sensor core and package it with a packaging shell to obtain a gas sensor.

[0014] Furthermore, the specific process parameters of the electrolytic oxidation additive in step 2 and step 4 are 4-6wt% boric acid, 5-7h electrolytic oxidation time, and a constant voltage of 29-30V.

[0015] Furthermore, in step three, the concentration of the phosphoric acid solution is 5-10wt%, the concentration of the chromic acid solution is 2-5wt%, the volume ratio of phosphoric acid to chromic acid is 1:1, and the soaking time of the preliminary chip substrate is 0.5-1 hour.

[0016] Furthermore, in step five, the signal electrode and the reference electrode are connected to the electrode pads respectively, and the thickness of the platinum film generated by magnetron sputtering is 1-2 μm.

[0017] Furthermore, in step six, the precious metal catalyst is iridium nitrate and palladium chloride, the mass ratio of aluminum nitrate to iridium nitrate and palladium chloride is 95:3:2, the binder is glycerol, the mass ratio of the doped powder to the binder is 1:2, the high-temperature calcination temperature is 600-800°C, and the high-temperature calcination time is 0.5-2h.

[0018] Furthermore, in step seven, the desensitizer is lead acetate solution, the concentration of the lead acetate solution is 5-6.5wt%, the high-temperature calcination temperature is 600-800°C, and the high-temperature calcination time is 0.5-2h.

[0019] Furthermore, in step eight, the packaging shell is a stainless steel powder metallurgy shell with a mesh size of 80 to 120 and a thickness of 1 to 2 mm for explosion-proof packaging.

[0020] A method for manufacturing a gas sensor, comprising a sensor core, leads and a packaging shell thereof, wherein the sensor core comprises a top heat insulation groove, a sensitive material layer, a bottom heat insulation groove, an electrode pad, a signal electrode, a reference electrode, an inactivated sensitive material layer and a chip substrate;

[0021] A top heat-insulating groove is arranged on the upper surface of the chip substrate, and a bottom heat-insulating groove is arranged on the lower surface. A signal electrode is arranged in the left area of ​​the top heat-insulating groove, and a reference electrode is arranged in the right area. The signal electrode area is covered with a sensitive material layer, and the reference electrode area is covered with an inactivation sensitive material layer; both ends of the signal electrode and the reference electrode are connected to electrode pads respectively.

[0022] Furthermore, the number of the electrode pads is 4, the electrode pads are arranged outside the top insulation groove, and the edge width of the electrode pad from the chip substrate is the same as the edge width of the bottom insulation groove from the chip substrate.

[0023] Furthermore, the top heat insulation groove and the bottom heat insulation groove are discontinuous rectangular frame structures, and the signal electrode and the reference electrode are arch structures.

[0024] Beneficial effects of the present invention:

[0025] The manufacturing method of a gas sensor described in the present invention adopts an additive manufacturing method of aluminum foil oxidation growth to manufacture a chip substrate, eliminating subtractive processes such as cutting, so that the chip substrate can be formed in one step.

[0026] The present invention discloses a method for manufacturing a gas sensor, wherein the signal electrode and the sensitive material of the signal electrode are sensitive to ammonia and hydrogen. When the concentration of ammonia and hydrogen changes, the resistance value thereof will change accordingly. The reference electrode is insensitive to ammonia and hydrogen, but the manufacturing process is similar to that of the signal electrode. The reference electrode is additionally sprayed with a desensitizer, and while being insensitive to ammonia and hydrogen, other properties are similar to those of the signal electrode. Using the reference electrode and the signal electrode simultaneously can effectively reduce environmental interference.

[0027] In a method for manufacturing a gas sensor described in the present invention, thermal insulation grooves are distributed around the signal electrode and the reference electrode. This structure slows down the heat loss, so that the ammonia and hydrogen sensors have a fast thermal response speed and low power consumption, and at the same time have higher structural strength than the hollow structure.

[0028] The manufacturing method of a gas sensor described in the present invention uses iridium nitrate and palladium chloride as noble metal catalysts, which can improve the detection accuracy of ammonia and hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a top view of the sensitive core of the present invention;

[0030] Figure 2 It is a right side view of the sensitive core of the present invention;

[0031] Figure 3 This is a front view of the sensitive core of the present invention;

[0032] Among them, 1 is the top insulation groove, 2 is the sensitive material layer, 3 is the bottom insulation groove, 4 is the electrode pad, 5 is the signal electrode, 6 is the reference electrode, 7 is the inactivated sensitive material layer, and 8 is the chip substrate. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with 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 are not used to limit the present invention, that is, the specific embodiments described are only part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0034] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0035] In order to further understand the content, features and effects of the present invention, the following specific implementation methods are given as examples, and the attached Figure 1 -Attached Figure 3 The detailed instructions are as follows:

[0036] Embodiment 1:

[0037] A method for manufacturing a gas sensor comprises the following steps:

[0038] Step 1: Cut the high-purity aluminum foil according to the size of the chip substrate to obtain the basic shape of the chip substrate;

[0039] Furthermore, the thickness of the high-purity aluminum foil is 0.2 to 0.25 mm;

[0040] Step 2: Place the basic shape of the chip substrate into an electrolytic device, add boric acid as an electrolyte for electrolytic oxidation and material addition, grow porous γ-Al2O3 material on the basic shape of the chip substrate, and obtain a preliminary chip substrate;

[0041] Furthermore, the specific process parameters of the electrolytic oxidation additive in step 2 are 4-6wt% boric acid, electrolytic oxidation time 5-7h, and constant voltage 29-30V;

[0042] Furthermore, the boric acid concentration used was 4%, and the oxidation growth was 7 hours;

[0043] Step 3, soaking the preliminary chip substrate in a chromic acid phosphate solution at room temperature to obtain a soaked preliminary chip substrate, then applying photoresist to the corresponding positions of the bottom insulation groove and the top insulation groove, and then covering the preliminary chip substrate coated with the photoresist with a photoresist plate to perform photosensitive curing;

[0044] Furthermore, in step three, the concentration of the phosphoric acid solution is 5-10wt%, the concentration of the chromic acid solution is 2-5wt%, the volume ratio of phosphoric acid to chromic acid is 1:1, and the soaking time of the preliminary chip substrate is 0.5-1 hour.

[0045] Step 4: Place the preliminary chip substrate after photosensitive curing into an electrolytic device, add boric acid as an electrolyte to perform electrolytic oxidation and material addition, and then remove the photoresist to obtain a chip substrate with a bottom insulation groove and a top insulation groove;

[0046] Furthermore, the specific process parameters of the electrolytic oxidation additive in step 4 are 4-6wt% boric acid, electrolytic oxidation time 5-7h, and constant voltage 29-30V;

[0047] Furthermore, the boric acid concentration used was 6%, and the oxidation growth was performed for 5 hours. The obtained alumina chip substrate was porous γ-Al2O3.

[0048] Step 5: On the upper surface of the chip substrate having the bottom heat insulation groove and the top heat insulation groove, a signal electrode, a reference electrode and an electrode pad composed of a platinum film are formed by using a magnetron sputtering film forming technology;

[0049] Furthermore, in step five, the signal electrode and the reference electrode are connected to the electrode pads respectively, and the thickness of the platinum film generated by magnetron sputtering is 1-2 μm.

[0050] Step 6: doping aluminum nitrate with a noble metal catalyst, mixing the doped powder with a binder into a slurry, stirring and mixing evenly, completely covering the signal electrode area and the reference electrode area, and then drying and calcining at a high temperature to obtain a preliminary sensor core;

[0051] Furthermore, in step 6, the precious metal catalyst is iridium nitrate and palladium chloride, the mass ratio of aluminum nitrate to iridium nitrate and palladium chloride is 95:3:2, the binder is glycerol, the mass ratio of the doped powder to the binder is 1:2, the high temperature calcination temperature is 600-800°C, and the high temperature calcination time is 0.5-2h;

[0052] In the step 6, the mass ratio of the doped aluminum nitrate, iridium nitrate and palladium chloride is 95:3:2, which makes the material sensitive to ammonia and hydrogen; the heat treatment temperature is 700° C., and the heat treatment time is 1 hour;

[0053] Step 7: spraying a desensitizer on the reference electrode area of ​​the preliminary sensor core, and then calcining at high temperature to obtain the sensor core;

[0054] Furthermore, in step seven, the desensitizer is lead acetate solution, the concentration of the lead acetate solution is 5-6.5wt%, the high temperature calcination temperature is 600-800°C, and the high temperature calcination time is 0.5-2h;

[0055] Further, the heat treatment temperature is 650°C and the heat treatment time is 1 hour;

[0056] Step 8: Weld the sensor core and package it with a packaging shell to obtain a gas sensor.

[0057] Furthermore, in step eight, the packaging shell is a stainless steel powder metallurgy shell with a mesh size of 80 to 120 and a thickness of 1 to 2 mm for explosion-proof packaging.

[0058] Furthermore, the chip substrate is manufactured by an additive process of aluminum oxide, and the top and bottom insulation grooves make the sensor heat up quickly and have a higher structural strength. The sensitive material is located at the signal electrode and its vicinity. When it is in a working state and the concentration of ammonia or hydrogen changes, it will cause the resistance value of the signal electrode to change. There are also sensitive materials at the reference electrode and its vicinity, but the activity of the sensitive material is removed by a desensitizer, and the reference electrode will not change its resistance value due to changes in the concentration of ammonia or hydrogen. The present invention manufactures a gas sensor with a simple manufacturing process, high sensitivity and low power consumption.

[0059] Embodiment 2:

[0060] A gas sensor manufactured by the manufacturing method of a gas sensor described in embodiment 1 comprises a sensor core, leads and a packaging shell thereof, wherein the sensor core comprises a top thermal insulation groove 1, a sensitive material layer 2, a bottom thermal insulation groove 3, an electrode pad 4, a signal electrode 5, a reference electrode 6, an inactivated sensitive material layer 7, and a chip substrate 8;

[0061] The upper surface of the chip substrate 8 is provided with a top insulation groove 1, and the lower surface is provided with a bottom insulation groove 3. The left area of ​​the top insulation groove 1 is provided with a signal electrode 5, and the right area is provided with a reference electrode 6. The signal electrode 5 area is covered with a sensitive material layer 2, and the reference electrode 6 area is covered with an inactivated sensitive material layer 7; both ends of the signal electrode 5 and the reference electrode 6 are respectively connected to electrode pads 4.

[0062] Furthermore, the number of the electrode pads 4 is 4, and the electrode pads 4 are arranged outside the top insulation groove 1 , and the edge width of the electrode pads 4 from the chip substrate 8 is the same as the edge width of the bottom insulation groove 3 from the chip substrate 8 .

[0063] Furthermore, the top heat-insulating groove 1 and the bottom heat-insulating groove 3 are discontinuous rectangular frame structures, and the signal electrode 5 and the reference electrode 6 are arch structures.

[0064] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0065] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for manufacturing a gas sensor, characterized in that: The steps include: Step 1: Cut the high-purity aluminum foil according to the size of the chip substrate to obtain the basic shape of the chip substrate; Step 2: Place the basic shape of the chip substrate into an electrolytic device, add boric acid as an electrolyte for electrolytic oxidation and material addition, grow porous γ-Al2O3 material on the basic shape of the chip substrate, and obtain a preliminary chip substrate; Step 3, soaking the preliminary chip substrate in a chromic acid phosphate solution at room temperature to obtain a soaked preliminary chip substrate, then applying photoresist to the corresponding positions of the bottom insulation groove and the top insulation groove, and then covering the preliminary chip substrate coated with the photoresist with a photoresist plate to perform photosensitive curing; Step 4: Place the preliminary chip substrate after photosensitive curing into an electrolytic device, add boric acid as an electrolyte to perform electrolytic oxidation and material addition, and then remove the photoresist to obtain a chip substrate with a bottom insulation groove and a top insulation groove; Step 5: On the upper surface of the chip substrate having the bottom heat insulation groove and the top heat insulation groove, a signal electrode, a reference electrode and an electrode pad composed of a platinum film are formed by using a magnetron sputtering film forming technology; Step 6: doping aluminum nitrate with a noble metal catalyst, mixing the doped powder with a binder into a slurry, stirring and mixing evenly, completely covering the signal electrode area and the reference electrode area, and then drying and calcining at a high temperature to obtain a preliminary sensor core; Step 7: spraying a desensitizer on the reference electrode area of ​​the preliminary sensor core, and then calcining at high temperature to obtain the sensor core; Step 8: Weld the sensor core and package it with a packaging shell to obtain a gas sensor.

2. The method for manufacturing a gas sensor according to claim 1, characterized in that: The specific process parameters of the electrolytic oxidation additive in step 2 and step 4 are 4-6wt% boric acid, 5-7h electrolytic oxidation time, and constant voltage of 29-30V.

3. A method for manufacturing a gas sensor according to claim 1 or 2, characterized in that: In step three, the concentration of the phosphoric acid solution is 5-10wt%, the concentration of the chromic acid solution is 2-5wt%, the volume ratio of phosphoric acid to chromic acid is 1:1, and the soaking time of the preliminary chip substrate is 0.5-1h.

4. The method for manufacturing a gas sensor according to claim 3, characterized in that: In step five, the signal electrode and the reference electrode are connected to the electrode pads respectively, and the thickness of the platinum film generated by magnetron sputtering is 1-2 μm.

5. The method for manufacturing a gas sensor according to claim 4, characterized in that: In step six, the precious metal catalyst is iridium nitrate and palladium chloride, the mass ratio of aluminum nitrate to iridium nitrate and palladium chloride is 95:3:2, the binder is glycerol, the mass ratio of the doped powder to the binder is 1:2, the high-temperature calcination temperature is 600-800°C, and the high-temperature calcination time is 0.5-2h.

6. The method for manufacturing a gas sensor according to claim 5, characterized in that: In step seven, the desensitizer is lead acetate solution, the concentration of the lead acetate solution is 5-6.5wt%, the temperature of high-temperature calcination is 600-800°C, and the time of high-temperature calcination is 0.5-2h.

7. The method for manufacturing a gas sensor according to claim 6, characterized in that: In step eight, the packaging shell is a stainless steel powder metallurgy shell with a mesh size of 80 to 120 and a thickness of 1 to 2 mm for explosion-proof packaging.

8. A gas sensor manufactured by the method for manufacturing a gas sensor according to any one of claims 1 to 7, characterized in that: The invention comprises a sensor core, leads and a packaging shell thereof, wherein the sensor core comprises a top heat-insulating groove (1), a sensitive material layer (2), a bottom heat-insulating groove (3), an electrode pad (4), a signal electrode (5), a reference electrode (6), an inactivated sensitive material layer (7) and a chip substrate (8); The chip substrate (8) is provided with a top heat insulation groove (1) on its upper surface and a bottom heat insulation groove (3) on its lower surface; a signal electrode (5) is provided in the left region of the top heat insulation groove (1) and a reference electrode (6) is provided in the right region; the signal electrode (5) region is covered with a sensitive material layer (2) and the reference electrode (6) region is covered with an inactivated sensitive material layer (7); and both ends of the signal electrode (5) and the reference electrode (6) are respectively connected to electrode pads (4).

9. A gas sensor manufactured by the method for manufacturing a gas sensor according to claim 8, characterized in that: The number of the electrode pads (4) is four, and the electrode pads (4) are arranged outside the top heat insulation groove (1), and the edge width of the electrode pads (4) from the chip substrate (8) is the same as the edge width of the bottom heat insulation groove (3) from the chip substrate (8).

10. A gas sensor manufactured by the method for manufacturing a gas sensor according to claim 9, characterized in that: The top heat insulation groove (1) and the bottom heat insulation groove (3) are discontinuous rectangular frame structures, and the signal electrode (5) and the reference electrode (6) are arch structures.

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