Metal film pressure core and preparation method thereof

Abstract

The present invention provides a metal film pressure core and a preparation method, which relates to the technical field of pressure sensor sensitive elements, so as to optimize the pressure core structure to a certain extent, improve the output sensitivity, zero temperature drift and sensitivity temperature drift of the pressure measuring bridge, and enhance the working temperature range and accuracy of the sensor. The metal film pressure core provided by the present invention includes an elastic substrate, an insulating layer, a compensation resistor, an alloy resistor, a silicon strain component, a connector and a lead; a pressure inlet is formed on the pressure-sensing side of the elastic substrate, the insulating layer is attached to the back pressure side of the elastic substrate, and the compensation resistor, the alloy resistor and the silicon strain component are all deposited on the insulating layer; the connector connects the alloy resistor and the silicon strain component to form a Wheatstone measuring bridge, one end of the lead is connected to the Wheatstone measuring bridge, and the other end is connected to an external signal processing circuit.

Description

Technical Field

[0001] The invention relates to the technical field of pressure sensor sensitive elements, and in particular to a metal film pressure core and a preparation method thereof. Background Art

[0002] Metal film pressure sensor is a pressure sensitive element that uses thin film or thick film technology to make a thin film strain circuit on a metal elastomer. The adhesive layer is replaced by a dielectric layer such as glass or ceramic. It has the advantages of small creep, good long-term stability, high reliability, and high temperature resistance.

[0003] The sputtered thin film force sensitive resistor made by thin film technology is a metal alloy material. On the one hand, the sensitivity of the sensor is low, and the output signal will cause a large measurement error after being amplified; on the other hand, in a wide temperature range working environment, due to the resistance-temperature characteristics of metal materials, it is generally a positive temperature coefficient, that is, the resistance value of the resistor will increase with the increase of temperature, and the temperature drift caused cannot be ignored, and the compensation circuit is complex, the compensation temperature range is narrow, and the accuracy is not high.

[0004] The force-sensitive resistor of the micro-melt sensor using thick-film silk-screen printing and high-temperature sintering technology is a semiconductor material. Compared with metal alloy materials, its sensitivity coefficient is high, which can be increased by about 50-100 times, but its resistance and temperature coefficient are also larger, generally a negative temperature coefficient, that is, the resistance value of the resistor will decrease with the increase of temperature. The temperature compensation in a wide temperature range and the accuracy in the full temperature range also face great challenges.

[0005] Therefore, there is an urgent need to provide a metal film pressure core and a preparation method to solve the problems existing in the prior art to a certain extent. Summary of the invention

[0006] The purpose of the present invention is to provide a metal film pressure core and a preparation method, so as to optimize the pressure core structure to a certain extent, improve the output sensitivity, zero temperature drift and sensitivity temperature drift of the pressure measuring bridge, and enhance the operating temperature range and accuracy of the sensor.

[0007] The metal film pressure core provided by the present invention comprises an elastic substrate, an insulating layer, a compensation resistor, an alloy resistor, a silicon strain component, a connector and a lead; a pressure inlet is formed on the pressure-sensing side of the elastic substrate, the insulating layer is attached to the back-pressure side of the elastic substrate, the compensation resistor, the alloy resistor and the silicon strain component are all deposited on the insulating layer; the connector connects the alloy resistor and the silicon strain component to form a Wheatstone measurement bridge, one end of the lead is connected to the Wheatstone measurement bridge, and the other end is connected to an external signal processing circuit.

[0008] The pressure inlet forms a fixed support portion and a thin film portion on the elastic matrix, the compensation resistor is arranged corresponding to the back pressure side of the fixed support portion, and the alloy resistor is arranged corresponding to the back pressure side of the thin film portion.

[0009] The metal film pressure core provided by the present invention further comprises a positioning layer, wherein the positioning layer is formed on the insulating layer and fixes the silicon strain component on the insulating layer.

[0010] Specifically, a protection layer is formed on the insulating layer, the positioning layer is formed on the protection layer, and the silicon strain component is fixed on the protection layer.

[0011] Furthermore, the insulating layer and the protective layer are both made of silicon dioxide material, the compensation resistor and the alloy resistor are both made of metal or alloy material, and the compensation resistor and the alloy resistor are both formed by magnetron sputtering coating technology.

[0012] Furthermore, an electrode film is formed on the back-pressure side of the elastic substrate, and the insulating layer, the compensation resistor, the alloy resistor, the electrode film and the protective layer are formed in sequence.

[0013] Wherein, the elastic matrix is ​​made of metal material, and the surface roughness of the back-pressure side of the elastic matrix formed by grinding and polishing does not exceed 0.1 mm.

[0014] Specifically, the positioning layer is micro-melted glass, formed by screen printing and high-temperature sintering processes, printed and fired on the protective layer, and the thickness of the positioning layer is 25 μm-50 μm.

[0015] Furthermore, the silicon strain assembly includes a silicon strain gauge and a silicon force sensitive resistor, the number of the silicon strain gauges is two, the number of the silicon force sensitive resistors is four, and they are arranged in pairs on the silicon strain gauge; the resistance change directions of the two silicon force sensitive resistors on the same silicon strain gauge are opposite; the number of the alloy resistors is the same as the number of the silicon force sensitive resistors, and two of the alloy resistors are located in the same area as the silicon force sensitive resistors on the two silicon strain gauges, and the other two alloy resistors are located in the same area as the other two force sensitive resistors on the two silicon strain gauges.

[0016] Compared with the prior art, the metal film pressure core provided by the present invention has the following advantages:

[0017] The metal film pressure core provided by the present invention comprises an elastic substrate, an insulating layer, a compensation resistor, an alloy resistor, a silicon strain component, a connector and a lead; a pressure inlet is formed on the pressure-sensing side of the elastic substrate, the insulating layer is attached to the back-pressure side of the elastic substrate, and the compensation resistor, the alloy resistor and the silicon strain component are all deposited on the insulating layer; the connector connects the alloy resistor and the silicon strain component to form a Wheatstone measuring bridge, one end of the lead is connected to the Wheatstone measuring bridge, and the other end is connected to an external signal processing circuit.

[0018] From this analysis, it can be seen that by forming a pressure inlet on the pressure-sensing side of the elastic body, the elastic matrix can be formed into a thin area. It can be understood that the thin area is more likely to deform, so the pressure sensing accuracy can be higher. Correspondingly, by attaching an insulating layer on the back pressure side, the elastic matrix and the compensation resistor, alloy resistor and silicon strain component can be isolated to prevent the resistor from being affected and ensure the detection accuracy.

[0019] The alloy resistor and silicon strain assembly formed on the insulating layer have a low pressure sensitivity coefficient of the alloy resistor, which is expressed as a positive temperature coefficient, while the pressure sensitivity coefficient of the silicon strain assembly is high, which is expressed as a negative temperature coefficient. Therefore, connecting the alloy resistor and the silicon strain assembly in series through a connector can improve the output sensitivity. When the temperature changes in a large range, the alloy resistor and the silicon strain assembly with positive and negative resistance temperature coefficients compensate each other and sense the temperature at the same time, resulting in a fast temperature response and high compensation accuracy, so that the resistance of a single bridge arm is maintained in a relatively constant state, thereby solving the problems of sensitivity and temperature drift from the pressure-sensitive element and the pressure measuring bridge, and improving the operating temperature range and accuracy of the sensor.

[0020] In addition, the present invention also provides a method for preparing a metal film pressure core, comprising the following steps: step one, processing a pressure inlet on the pressure-sensing side of an elastic substrate, forming a thin film portion and a fixed support portion, and grinding and polishing the back-pressure side of the elastic substrate; step two, sequentially forming an insulating layer, a compensation resistor, an alloy resistor, an electrode film and a protective layer on the back-pressure side of the elastic substrate, and fixing a silicon strain component on the insulating layer using a positioning layer; step three, connecting the alloy resistor and the silicon strain component through a connector to form a Wheatstone measurement bridge; step four, welding a lead, connecting one end of the lead to the Wheatstone measurement bridge, and the other end to an external signal processing circuit.

[0021] By adopting the preparation method provided in the present application, the metal film pressure core provided in the present application can be formed, thereby providing a metal film pressure core with a higher operating temperature range and precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A cross-sectional view of a metal film pressure core provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the arrangement of alloy resistors, silicon strain components and compensation resistors on an elastic substrate in a metal film pressure core provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of the structure of a Wheatstone bridge composed of an alloy resistor, a silicon strain gauge component and a compensation resistor in a metal film pressure core provided by an embodiment of the present invention;

[0026] Figure 4 The present invention provides a flowchart of the preparation method of the present invention.

[0027] In the figure: 1-elastic matrix; 101-pressure inlet; 102-fixed support; 103-thin film; 104-tensile stress area; 105-compressive stress area; 2-insulating layer; 3-positioning layer; 4-compensation resistor; 5-alloy resistor; 6-silicon strain gauge; 7-silicon force sensitive resistor; 8-protective layer; 9-electrode film; 10-connector; 11-lead. DETAILED DESCRIPTION

[0028] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0029] In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or are the positions or positional relationships in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0033] For ease of description, spatial relative terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the drawings. Such spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings.

[0034] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0035] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0036] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application. In addition, the technical solutions between the various embodiments may be combined with each other, but must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present application.

[0037] like Figure 1 As shown, the present invention provides a metal film pressure core, including an elastic substrate 1, an insulating layer 2, a compensation resistor 4, an alloy resistor 5, a silicon strain component, a connector 10 and a lead 11; a pressure inlet 101 is formed on the pressure-sensing side of the elastic substrate 1, the insulating layer 2 is attached to the back-pressure side of the elastic substrate 1, and the compensation resistor 4, the alloy resistor 5 and the silicon strain component are all deposited on the insulating layer 2; the connector 10 connects the alloy resistor 5 and the silicon strain component to form a Wheatstone measurement bridge, one end of the lead 11 is connected to the Wheatstone measurement bridge, and the other end is connected to an external signal processing circuit.

[0038] Compared with the prior art, the metal film pressure core provided by the present invention has the following advantages:

[0039] The metal film pressure core provided by the present invention can form a thin area in the elastic base 1 by forming a pressure inlet 101 on the pressure sensing side of the elastic body. It can be understood that the thin area is more likely to deform, so the pressure sensing accuracy can be higher. Accordingly, the elastic base 1 and the compensation resistor 4, the alloy resistor 5 and the silicon strain component can be isolated by the insulating layer 2 attached to the back pressure side, so as to avoid the resistor being affected and ensure the detection accuracy.

[0040] The alloy resistor 5 and the silicon strain assembly formed on the insulating layer 2 have a low pressure sensitivity coefficient, which is expressed as a positive temperature coefficient, while the pressure sensitivity coefficient of the silicon strain assembly is high, which is expressed as a negative temperature coefficient. Therefore, the output sensitivity can be improved by connecting the alloy resistor 5 and the silicon strain assembly in series through the connector 10. When the temperature changes in a large range, the alloy resistor 5 and the silicon strain assembly with positive and negative resistance temperature coefficients compensate each other and sense the temperature at the same time, so that the temperature response is fast and the compensation accuracy is high, so that the single bridge arm resistance is maintained in a relatively constant state, so that the sensitivity and temperature drift problems can be solved from the pressure-sensitive element and the pressure measuring bridge, thereby improving the operating temperature range and accuracy of the sensor.

[0041] Preferably, if Figure 1 As shown, the pressure inlet 101 in the present application forms the elastic base 1 into a fixed support portion 102 and a thin film portion 103 , the compensation resistor 4 is arranged corresponding to the back pressure side of the fixed support portion 102 , and the alloy resistor 5 is arranged corresponding to the back pressure side of the thin film portion 103 .

[0042] In the actual pressure measurement stage, after the thin film part 103 is deformed by pressure, the pressure value needs to be obtained through the resistance change of the alloy resistor 5 and the silicon strain component on the back pressure side of the thin film part 103. Therefore, by forming the alloy resistor 5 and the silicon strain component on the back pressure side of the thin film part 103, the pressure change can be accurately sensed.

[0043] Accordingly, since the compensation resistor 4 is used to compensate for the resistance value, it does not need to sense the pressure change of the elastic base 1 . Therefore, by arranging the compensation resistor 4 corresponding to the fixed support portion 102 , the stability of the compensation resistor 4 can be improved.

[0044] The compensation resistor 4 in the present application includes two types, one of which is connected in series to the bridge arm of the Wheatstone bridge, and balances the bridge arm resistance by fine-tuning the resistance value to achieve zero-point output and zero-point temperature drift. The other is connected in series to the power input end of the bridge to compensate for the sensitivity temperature drift of the sensor.

[0045] Alternatively, if Figure 1 As shown, the metal film pressure core provided by the present invention further includes a positioning layer 3 , which is formed on the insulating layer 2 to fix the silicon strain component on the insulating layer 2 .

[0046] Preferably, the positioning layer 3 in the present application is a micro-melted glass material, and the micro-melted glass in the present application is integrated onto the silicon dioxide protective layer 8 by screen printing and high-temperature sintering process, and the thickness of the positioning layer 3 is 25μm-50μm.

[0047] In actual preparation, the micro-melted glass is first printed and burned on the protective layer 8 by a screen printing process, and then solidified and formed by a high-temperature sintering process. Finally, the silicon strain component is bonded to the micro-melted glass, and the silicon strain component and the micro-melted glass are integrated by high-temperature sintering to achieve stable positioning of the silicon strain component.

[0048] Alternatively, if Figure 1 As shown, a protective layer 8 is formed on the insulating layer 2 in the present application, a positioning layer 3 is formed on the protective layer 8 , and the silicon strain component is fixed on the protective layer 8 .

[0049] The insulating layer 2 and the protective layer 8 in the present application are both formed of silicon dioxide. In actual preparation, the insulating layer 2 of silicon dioxide is first formed on the elastic substrate 1, and then the electrode film 9, the alloy resistor 5 and the compensation resistor 4 are deposited on the insulating layer 2, and finally the silicon dioxide protective layer 8 is deposited. After the protective layer 8 is deposited, the micro-melted glass is screen-printed on the protective film using a screen printing process, and the silicon strain component is bonded to the micro-melted glass after solidification, and is fused with the micro-melted glass through high-temperature sintering. Finally, the alloy resistor 5 is connected to the silicon strain component through a connector 10 to form a Wheatstone bridge, and the preparation of the metal film pressure core is completed.

[0050] It can be understood that the connector 10 actually connects the electrode film 9 and the silicon strain assembly mentioned above. Since the electrode film 9 is in contact with the alloy resistor 5, the circuit can be connected.

[0051] Preferably, the material of the electrode film 9 in the present application is gold. A mask is first formed on the gold layer by photolithography, and then an electrode pattern is etched out by etching liquid to facilitate the subsequent forming of the alloy resistor 5 and the compensation resistor 4.

[0052] It should be additionally explained here that the compensation resistor 4 and the alloy resistor 5 in the present application are both made of metal or alloy materials, and the compensation resistor 4 and the alloy resistor 5 are both formed by magnetron sputtering coating technology.

[0053] Since the compensation resistor 4 and the alloy resistor 5 in the present application are formed on the elastic substrate 1 by magnetron sputtering coating technology, the alloy resistor 5 can form a low pressure sensitivity coefficient, which is expressed as a positive temperature coefficient. The silicon strain component adopts thick film screen printing and high temperature sintering technology to actually form a semiconductor material, so that the pressure sensitivity coefficient is high, which is expressed as a negative temperature coefficient. The silicon strain component and the alloy resistor 5 in the present application are connected in series to form a Wheatstone bridge. Therefore, when the temperature changes in a large range, the silicon strain component and the alloy resistor 5 can compensate each other, so that the temperature can be felt at the same time, so that the temperature response is fast, the compensation accuracy is high, and the single bridge arm resistance is maintained in a relatively constant state, which fundamentally improves the output sensitivity, zero temperature drift and sensitivity temperature drift of the pressure measuring bridge, and improves the operating temperature range and accuracy of the sensor.

[0054] Optionally, the elastic substrate 1 in the present application is made of metal material, and the surface roughness of the back-pressure side of the elastic substrate 1 formed by grinding and polishing does not exceed 0.1 mm.

[0055] In the present application, the metal material of the elastic matrix 1 is specifically 17-4PH stainless steel (martensitic precipitation hardening stainless steel), so as to ensure the sputtering forming of the above-mentioned alloy resistor 5 and silicon strain assembly and other structures, and ensure the structural strength of the pressure core.

[0056] It is understandable that if Figure 1-Figure 3 As shown, the silicon strain assembly in the present application includes a silicon strain gauge 6 and a silicon force sensitive resistor 7, the number of the silicon strain gauges 6 is two, the number of the silicon force sensitive resistors 7 is four, and they are arranged in pairs on the silicon strain gauge 6; the resistance change directions of the two silicon force sensitive resistors 7 on the same silicon strain gauge 6 are opposite; the number of alloy resistors 5 is the same as the number of silicon force sensitive resistors 7, and two of the alloy resistors 5 are located in the same area with the silicon force sensitive resistors 7 on the two silicon strain gauges 6, and the other two alloy resistors 5 are located in the same area with the other two force sensitive resistors on the two silicon strain gauges 6.

[0057] like Figure 2 Combination Figure 3 As shown, the number of silicon strain gauges 6 in the present application is two, and two silicon force sensitive resistors 7 are integrated on each silicon strain gauge 6, and the two silicon force sensitive resistors 7 and the two alloy resistors 5 located at the inner position are located in the tensile stress zone 104 of the elastic matrix 1, while the two silicon force sensitive resistors 7 and the two alloy resistors 5 located at the outer position are located in the compressive stress zone 105 of the elastic matrix 1.

[0058] When under pressure, the resistance of one silicon force sensitive resistor 7 on one of the silicon strain gauges 6 increases, while the resistance of the other silicon force sensitive resistor 7 decreases. Correspondingly, the resistance of the silicon force sensitive resistor 7 on the other silicon strain gauge 6, which is located in the same stress zone as the silicon force sensitive resistor 7 with increased resistance, increases, while the resistance of the other silicon force sensitive resistor 7 on the other silicon strain gauge 6 decreases, and the above resistance changes are equal.

[0059] Furthermore, when the silicon strain gauge 6 is subjected to pressure, the resistance values ​​of the two groups of silicon force sensitive resistors 7 change in opposite directions, and there are two ways of having the same size. In one method, the silicon force sensitive resistors 7 are all located in the same stress zone of the elastic matrix 1, that is, in the tensile stress zone 104 or the compressive stress zone 105, and the crystal directions of the crystal planes where the two groups of silicon force sensitive resistors 7 are located are perpendicular to each other. At this time, the silicon strain gauge 6 is a silicon-sapphire strain gauge using a heteroepitaxial growth process.

[0060] The present application preferably adopts that one group of silicon force sensitive resistors 7 is located in the tensile stress region 104 of the elastic substrate 1, and the other group is located in the compressive stress region 105, and the crystal orientation of the crystal planes where the two groups of silicon force sensitive resistors 7 are located is the same, such as Figure 2 As shown, the silicon strain gauge 6 is a half-bridge silicon strain gauge.

[0061] It should be noted here that the connector 10 in the present application is a bonding wire, and the connector 10 is made of gold wire. Through the wire bonding process 11, the interconnection and bridging between the alloy resistor 5 and the silicon force sensitive resistor 7 are realized, and the connector 10 made of gold wire can improve the high temperature resistance of the sensor.

[0062] It should be further explained here that the alloy resistor 5 and the compensation resistor 4 in the present application are both made of nickel-based high-temperature alloy, which has excellent high-temperature strength, corrosion resistance and oxidation resistance as well as good resistance to stress corrosion cracking.

[0063] It can be understood that since the number of alloy resistors 5 in the present application is also four, and two of them correspond to the tensile stress zone 104, and the other two correspond to the compressive stress zone 105, therefore, when the measured pressure causes the film portion 103 to deform, the resistance values ​​of the alloy resistors 5 in the tensile stress zone 104 and the compressive stress zone 105 change, and the resistance values ​​are equal in magnitude and opposite in direction, that is, when the resistance values ​​of the alloy resistor 5 and the silicon force sensitive resistor 7 in the tensile stress zone 104 increase, the resistance values ​​of the alloy resistor 5 and the silicon force sensitive resistor 7 in the compressive stress zone 105 decrease.

[0064] In addition, if Figure 4As shown, the present invention also provides a method for preparing a metal film pressure core, comprising the following steps: step one, processing a pressure inlet 101 on the pressure-sensing side of an elastic substrate 1, and forming a film portion 103 and a fixed support portion 102, and grinding and polishing the back-pressure side of the elastic substrate 1; step two, forming an insulating layer 2, a compensation resistor 4, an alloy resistor 5, an electrode film 9 and a protective layer 8 in sequence on the back-pressure side of the elastic substrate 1, and fixing the silicon strain component on the insulating layer 2 by using a positioning layer 3; step three, connecting the alloy resistor 5 and the silicon strain component through a connector 10 to form a Wheatstone measuring bridge; step four, welding a lead 11, connecting one end of the lead 11 to the Wheatstone measuring bridge, and connecting the other end to an external signal processing circuit.

[0065] By adopting the preparation method provided in the present application, the metal film pressure core provided in the present application can be formed, thereby providing a metal film pressure core with a higher operating temperature range and precision.

[0066] Specifically, step 2 in the present application includes: in a vacuum chamber with a vacuum degree of 6×10-4Pa, using a silicon dioxide target material with a purity better than 99.99%, using magnetron sputtering and ion beam sputtering coating processes, silicon dioxide is deposited on the back pressure side of the elastic substrate 1, and the thickness is about 500nm;

[0067] The method also includes depositing high-purity gold as a target material on the silicon dioxide insulating layer 2 in a vacuum chamber with a vacuum degree of 6×10-4 Pa to form an electrode film 9 and to produce an electrode pattern;

[0068] It also includes using a high-temperature nickel-based alloy as a target material in a vacuum chamber with a vacuum degree of 6×10-4Pa, and adopting magnetron sputtering and ion beam sputtering coating processes to deposit the nickel-based alloy in the form of molecules on the silicon dioxide insulating layer 2 to produce a strain circuit pattern with a thickness of about 250nm.

[0069] The strain circuit includes four alloy resistors 5 formed in the tensile stress area 104 and the compressive stress area 105 of the elastic substrate 1 and a compensation resistor 4 located on the fixed support portion 102;

[0070] It also includes using magnetron sputtering and ion beam sputtering coating processes to deposit a silicon dioxide protective layer 8 on the strain circuit pattern;

[0071] It also includes using a screen printing process to screen print the micro-melted glass slurry onto the silicon dioxide protective layer 8, and then solidifying and forming it through a high-temperature sintering technology, and the sintering temperature is 500° C.-600° C., and the thickness is 25 μm-40 μm;

[0072] It also includes bonding the silicon strain gauge 6 to the micro-melted glass and fusing it with the glass through high-temperature sintering. The sintering temperature is 500°C-600°C. A pair of silicon force-sensitive resistors 7 on the half-bridge silicon strain gauge 6 are respectively located in the tensile stress zone 104 and the compressive stress zone 105 of the elastic substrate 1.

[0073] Specifically, in step three, the alloy resistor 5 and the silicon force-sensitive resistor 7 are connected in series through the connector 10 by using a gold wire bonding process to form a Wheatstone bridge.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Metal film pressure core, characterized in that: It includes an elastic substrate, an insulating layer, a compensation resistor, an alloy resistor, a silicon strain component, a connector and a lead; A pressure inlet is formed on the pressure-sensing side of the elastic substrate, the insulating layer is attached to the back-pressure side of the elastic substrate, and the compensation resistor, the alloy resistor and the silicon strain component are all deposited on the insulating layer; The connecting piece connects the alloy resistor and the silicon strain assembly to form a Wheatstone measuring bridge, one end of the lead is connected to the Wheatstone measuring bridge, and the other end is connected to an external signal processing circuit; The silicon strain component includes a silicon strain gauge and a silicon force-sensitive resistor, wherein the number of the silicon strain gauges is two, and the number of the silicon force-sensitive resistors is four, and the silicon strain gauges are arranged on the silicon strain gauges in pairs; The resistance values ​​of the two silicon force-sensitive resistors on the same silicon strain gauge change in opposite directions; The number of the alloy resistors is the same as the number of the silicon force-sensitive resistors, and two of the alloy resistors are located in the same area as the silicon force-sensitive resistors on the two silicon strain gauges, and the other two alloy resistors are located in the same area as the other two force-sensitive resistors on the two silicon strain gauges; Each bridge arm of the Wheatstone measuring bridge is connected in series with an alloy resistor and a silicon force-sensitive resistor, the alloy resistor has a positive temperature coefficient, and the silicon force-sensitive resistor has a negative temperature coefficient. When the temperature changes over a large range, the alloy resistor and the silicon force-sensitive resistor with positive and negative resistance temperature coefficients connected in series on each bridge arm compensate each other.

2. The metal film pressure core according to claim 1, characterized in that: The pressure inlet forms a fixed support portion and a thin film portion on the elastic matrix, the compensation resistor is arranged corresponding to the back pressure side of the fixed support portion, and the alloy resistor is arranged corresponding to the back pressure side of the thin film portion.

3. The metal film pressure core according to claim 1, characterized in that: The invention also comprises a positioning layer, wherein the positioning layer is formed on the insulating layer and fixes the silicon strain component on the insulating layer.

4. The metal film pressure core according to claim 3, characterized in that: A protection layer is formed on the insulating layer, the positioning layer is formed on the protection layer, and the silicon strain component is fixed on the protection layer.

5. The metal film pressure core according to claim 4, characterized in that: The insulating layer and the protective layer are both made of silicon dioxide material, the compensation resistor and the alloy resistor are both made of metal or alloy material, and the compensation resistor and the alloy resistor are both formed by magnetron sputtering coating technology.

6. The metal film pressure core according to claim 5, characterized in that: An electrode film is also formed on the back pressure side of the elastic substrate, and the insulating layer, the compensation resistor, the alloy resistor, the electrode film and the protective layer are formed in sequence.

7. The metal film pressure core according to claim 1, characterized in that: The elastic matrix is ​​made of metal material, and the surface roughness of the back-pressure side of the elastic matrix formed by grinding and polishing does not exceed 0.1 mm.

8. The metal film pressure core according to claim 4, characterized in that: The positioning layer is made of micro-melted glass, formed by screen printing and high-temperature sintering processes, printed and fired on the protective layer, and has a thickness of 25 μm-50 μm.

9. A method for preparing a metal film pressure core according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: processing a pressure inlet on the pressure-sensing side of the elastic base, forming a film portion and a fixed support portion, and grinding and polishing the back-pressure side of the elastic base; Step 2: forming an insulating layer, a compensation resistor, an alloy resistor, an electrode film and a protective layer in sequence on the back pressure side of the elastic substrate, and fixing the silicon strain component on the insulating layer by using a positioning layer; Step 3: Connect the alloy resistor and the silicon strain gauge assembly through a connector to form a Wheatstone measurement bridge; Step 4: Weld a lead wire, connect one end of the lead wire to the Wheatstone measurement bridge, and connect the other end of the lead wire to an external signal processing circuit.

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