A method of assembling a sensor piezoelectric assembly

Abstract

This invention discloses an assembly method for a piezoelectric sensor component, relating to the field of sensor manufacturing technology. Its main technical solution includes the following operations: S1, placing a quartz wafer in a vacuum cleaning chamber and performing ion bombardment cleaning on the quartz wafer using glow discharge; S2, depositing electrode layers on both sides of the quartz wafer using magnetron vacuum ion sputtering; wherein the electrode layers comprise an adhesion layer, a barrier layer, and a conductive layer sequentially arranged; S3, performing low-temperature annealing on the quartz wafer with the deposited electrode layers in a vacuum environment. The magnetron vacuum ion sputtering method forms nanoscale multilayer electrodes on the quartz wafer, aiming to enhance electrode adhesion, high-temperature resistance, and oxidation resistance, thereby reducing the risk of signal drift.

Description

Technical Field

[0001] This invention relates to the field of sensor manufacturing technology, and more specifically to an assembly method for a sensor piezoelectric assembly. Background Technology

[0002] A cavity pressure sensor is a precision device specifically designed to monitor and measure pressure changes within the mold cavity during injection molding. By acquiring real-time pressure data from the mold cavity, it provides crucial technical support for optimizing injection molding processes, improving product quality, and reducing production costs. The core function of a cavity pressure sensor is to convert the physical pressure within the mold cavity into a measurable electrical signal output. This sensor is typically installed inside or near the mold cavity, accurately capturing pressure changes as molten plastic fills the mold cavity during injection molding.

[0003] However, under the existing coating process conditions, the electrode adhesion of the cavity pressure sensor is poor, which makes the cavity pressure sensor prone to detachment or oxidation in high-temperature environments, thus causing signal drift problems. Summary of the Invention

[0004] The purpose of this invention is to provide an assembly method for a sensor piezoelectric component, which solves the problem that under existing coating process conditions, the electrode adhesion of the cavity pressure sensor is poor, making the cavity pressure sensor prone to detachment or oxidation in high-temperature environments, thereby causing signal drift.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for assembling a sensor piezoelectric assembly is provided, comprising the following operations:

[0007] S1, the quartz wafer is placed in the vacuum cleaning chamber and the quartz wafer is cleaned by ion bombardment using glow discharge.

[0008] S2, using magnetron vacuum ion sputtering, electrode layers are deposited on both sides of a quartz wafer; wherein the electrode layers comprise an adhesion layer, a barrier layer, and a conductive layer arranged sequentially.

[0009] S3, a low-temperature annealing process is performed on a quartz wafer with an electrode layer deposited in a vacuum environment.

[0010] A further option is that the adhesion layer is made of titanium or chromium, and the thickness of the adhesion layer is 50-100 nm.

[0011] A further alternative is that the barrier layer is made of nickel or platinum.

[0012] A further proposed solution is that the conductive layer is made of gold, and the thickness of the conductive layer is 30-300 nm.

[0013] A further step is to include chamfering the edges of the quartz wafer before S1; the chamfer angle is 45°±15° and the chamfer width is 0.05mm-0.2mm.

[0014] A further step is to include polishing the quartz wafer before chamfering its edges, so that the parallelism between the two sides of the quartz wafer is ≤1µm and the surface roughness Ra of the quartz wafer is ≤0.1µm.

[0015] A further step is to include S4 after S3, in which the insulating pad, lower electrode, first quartz crystal, second quartz crystal, upper electrode and pressure-transmitting diaphragm are sequentially placed into the stainless steel housing, and a butterfly spring pre-tightening device is used to make the pre-tightening force between the stainless steel housing and the pressure-transmitting diaphragm 1-1.5 times the full-scale pressure of the sensor to obtain the pre-assembled sensor assembly; wherein the first quartz crystal and the second quartz crystal are stacked in opposite directions.

[0016] A further step is to include, after S4, placing the pre-installed sensor assembly into a vacuum brazing furnace and ensuring the pressure in the furnace is ≤10. -3 pa; using gold-nickel or silver-copper as the brazing filler metal, and raising the temperature inside the vacuum brazing furnace to above the melting point of the brazing filler metal under vacuum conditions, so that the brazing filler metal forms a metallurgical bonding layer between the pressure-transmitting diaphragm and the stainless steel shell, and between the electrode leads and the insulator.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] A nanoscale multilayer electrode was formed on a quartz wafer using magnetron vacuum ion sputtering. The aim was to enhance electrode adhesion, high-temperature resistance, and oxidation resistance, thereby reducing the risk of signal drift. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating an assembly method for a sensor piezoelectric component in this embodiment. Detailed Implementation

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Example: This example provides a method for assembling a sensor piezoelectric assembly, such as... Figure 1 As shown, the following operations are included:

[0022] S100. Place the quartz wafer in a vacuum cleaning chamber and use glow discharge to perform ion bombardment cleaning on the quartz wafer;

[0023] In this embodiment, before S100, the edge of the quartz wafer is chamfered; wherein the chamfer angle is 45°±15° and the chamfer width is 0.05mm-0.2mm.

[0024] In this embodiment, before chamfering the edge of the quartz wafer, the quartz wafer is further polished to make the parallelism between the two sides of the quartz wafer ≤1um and the surface roughness Ra of the quartz wafer ≤0.1um.

[0025] For example, in the implementation process, the quartz crystal is first subjected to ultra-precision machining and edge passivation treatment to obtain a quartz wafer that meets the requirements. The process of ultra-precision machining and edge passivation treatment of the quartz crystal includes directional cutting and grinding, as well as edge chamfering.

[0026] The process of directional cutting and grinding is as follows: high-purity artificial quartz crystals are selected and precisely cut along the X-axis or Y-axis to obtain quartz wafers; a double-sided grinding machine is used to grind the quartz wafers so that the parallelism between the two sides of the quartz wafers is ≤1um and the surface roughness Ra of the quartz wafers is ≤0.1um.

[0027] The edge chamfering process is as follows: CNC precision grinding is used to chamfer the edge of the quartz wafer, and the chamfer angle is 45°±15°, or a rounded corner is used, and the chamfer width is 0.05mm-0.2mm.

[0028] The assembly method of the sensor piezoelectric component in this embodiment employs CNC precision grinding to chamfer the edges of the quartz wafer. This aims to eliminate sharp edges, thereby reducing stress concentration under high voltage that could lead to edge chipping, and also minimizing the risk of edge leakage current.

[0029] After the quartz wafer undergoes an edge chamfering process, it is placed in a vacuum cleaning chamber and subjected to ion bombardment cleaning using glow discharge to remove organic contaminants and oxide layers from the surface of the quartz wafer.

[0030] S200. Electrode layers are deposited on both sides of a quartz wafer using a magnetron vacuum ion sputtering method; wherein the electrode layers comprise an adhesion layer, a barrier layer, and a conductive layer disposed sequentially.

[0031] In this embodiment, the adhesion layer is titanium or chromium, and the thickness of the adhesion layer is 50-100 nm.

[0032] In this embodiment, the barrier layer is nickel or platinum.

[0033] In this embodiment, the conductive layer is gold, and the thickness of the conductive layer is 30-300 nm.

[0034] For example, during implementation, magnetron vacuum ion sputtering technology is used to deposit electrode layers on both sides of a quartz wafer.

[0035] The electrode layer assembly comprises an adhesion layer, a barrier layer, and a conductive layer, which are sequentially deposited on the side surface of the quartz wafer. Specifically, the adhesion layer is deposited on the side surface of the quartz wafer, the barrier layer is deposited on the side of the adhesion layer away from the quartz wafer, and the conductive layer is deposited on the side of the barrier layer away from the quartz wafer.

[0036] The adhesive layer is made of titanium or chromium and has a thickness of 50-100 nm to ensure that the electrode and the quartz wafer form a strong chemical bond.

[0037] The barrier layer is made of nickel or platinum to reduce the risk of substrate atomic diffusion.

[0038] The conductive layer is made of gold and has a thickness of 30-300 nm to provide a low-resistance conductive path.

[0039] S300. In a vacuum environment, a quartz wafer with an electrode layer is subjected to low-temperature annealing.

[0040] For example, during the implementation process, a quartz wafer with deposited electrode layers is subjected to low-temperature annealing in a vacuum environment. This is intended to eliminate sputtering stress and thereby improve the film density.

[0041] In this embodiment, after S300, there is also S400, in which the insulating pad, lower electrode, first quartz crystal, second quartz crystal, upper electrode and pressure-transmitting diaphragm are sequentially placed into the stainless steel housing, and the pre-tightening device of the butterfly spring is used to make the pre-tightening force between the stainless steel housing and the pressure-transmitting diaphragm 1-1.5 times the full-scale pressure of the sensor to obtain the pre-assembled sensor assembly; wherein the first quartz crystal and the second quartz crystal are stacked in opposite directions.

[0042] For example, during implementation, a preload device is used to precisely assemble quartz wafers after low-temperature annealing. The process of precisely assembling quartz wafers after low-temperature annealing using a preload device includes stacking, constant force preload, and setting the preload force.

[0043] The stacking process involves sequentially placing an insulating pad, a lower electrode, a quartz crystal assembly, an upper electrode, and a pressure-transmitting diaphragm within a stainless steel casing. The quartz crystal assembly comprises two quartz crystals, designated as the first and second crystals, which are stacked in reverse order. This is intended to eliminate the pyroelectric effect.

[0044] The constant force preload process involves introducing two disc springs as preload devices. These disc springs possess non-linear characteristics, enabling them to maintain a relatively constant preload even under high-temperature expansion.

[0045] Two disc springs are respectively positioned against the stainless steel housing on the side away from the pressure-transmitting diaphragm and on the side of the pressure-transmitting diaphragm away from the upper electrode. A force-controlled tightening machine is used to drive the two disc springs closer together, so that the two disc springs precisely apply axial preload to the quartz crystal assembly.

[0046] The preload setting process involves applying a preload force of 1-1.5 times the full-scale pressure of the sensor to the disc spring between the stainless steel housing and the pressure-transmitting diaphragm, resulting in a pre-assembled sensor assembly. This aims to ensure that the quartz crystal assembly remains under pressure throughout its operating range, thereby reducing the risk of loosening or tensile stress in the quartz crystal assembly.

[0047] In this embodiment, after S400, the method further includes: placing the pre-installed sensor assembly into a vacuum brazing furnace, and ensuring that the pressure in the vacuum brazing furnace is ≤10. -3 pa; using gold-nickel or silver-copper as the brazing filler metal, and raising the temperature inside the vacuum brazing furnace to above the melting point of the brazing filler metal under vacuum conditions, so that the brazing filler metal forms a metallurgical bonding layer between the pressure-transmitting diaphragm and the stainless steel shell, and between the electrode leads and the insulator.

[0048] For example, during implementation, the pre-installed sensor assembly is vacuum-sealed. The process of vacuum-sealing the pre-installed sensor assembly includes creating a vacuum environment and high-temperature brazing.

[0049] The process of creating the vacuum environment involves placing the pre-installed sensor components into a vacuum brazing furnace and ensuring the pressure inside the furnace is ≤10. -3 pa.

[0050] The high-temperature brazing process involves using gold-nickel (Au-Ni) or silver-copper (Ag-Cu) brazing filler metal and heating it in a vacuum brazing furnace to above the melting point of the filler metal, so that a metallurgical bond is formed between the pressure-transmitting diaphragm and the stainless steel shell, as well as between the electrode leads and the insulator.

[0051] The assembly method for the sensor piezoelectric assembly in this embodiment utilizes a vacuum environment to reduce the risk of oxidation and porosity at the welding interface. This aims to effectively ensure the airtightness of the sensor assembly (leakage rate < 1 × 10⁻⁶). -9 Pa.m 3 The purpose is to achieve high insulation resistance ( / s).

[0052] The assembly method of the sensor piezoelectric component in this embodiment has the following aspects: First, a unique edge chamfering process is used to effectively disperse edge stress, increasing the pressure resistance limit of the quartz wafer by more than 30%. Second, a magnetron vacuum ion sputtering method is used to form nanoscale multilayer electrodes on the quartz wafer. This aims to enhance electrode adhesion, high temperature resistance, and oxidation resistance, thereby reducing the risk of signal drift. Third, a disc spring preload device is used to effectively compensate for the differences in the coefficients of thermal expansion of different materials at high temperatures. This aims to effectively ensure a constant preload force, thereby significantly reducing hysteresis error (hysteresis error < 0.2%FS). Fourth, a vacuum welding process is used to ensure the absolute sealing and electrical insulation reliability of the sensor component in harsh industrial environments.

[0053] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter arrangement within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A method for assembling a piezoelectric sensor assembly, characterized in that, Includes the following operations: S1, the quartz wafer is placed in the vacuum cleaning chamber and the quartz wafer is cleaned by ion bombardment using glow discharge. S2, using magnetron vacuum ion sputtering, electrode layers are deposited on both sides of a quartz wafer; wherein the electrode layers comprise an adhesion layer, a barrier layer, and a conductive layer arranged sequentially. S3, a low-temperature annealing process is performed on a quartz wafer with an electrode layer deposited in a vacuum environment.

2. The assembly method according to claim 1, characterized in that: The adhesive layer is made of titanium or chromium, and the thickness of the adhesive layer is 50-100 nm.

3. The assembly method according to claim 1, characterized in that: The barrier layer is made of nickel or platinum.

4. The assembly method according to claim 1, characterized in that: The conductive layer is made of gold, and the thickness of the conductive layer is 30-300 nm.

5. The assembly method according to claim 1, characterized in that, Before S1, the edge of the quartz wafer is chamfered; the chamfer angle is 45°±15° and the chamfer width is 0.05mm-0.2mm.

6. The assembly method according to claim 5, characterized in that, Before chamfering the edges of the quartz wafer, the quartz wafer is also polished to ensure that the parallelism between the two sides of the quartz wafer is ≤1µm and the surface roughness Ra of the quartz wafer is ≤0.1µm.

7. The assembly method according to claim 5, characterized in that, After S3, it also includes: S4. The insulating pad, lower electrode, first quartz crystal, second quartz crystal, upper electrode and pressure-transmitting diaphragm are placed into the stainless steel housing in sequence, and the pre-tightening device of the butterfly spring is used to make the pre-tightening force between the stainless steel housing and the pressure-transmitting diaphragm 1-1.5 times the full-scale pressure of the sensor to obtain the pre-assembled sensor assembly; wherein the first quartz crystal and the second quartz crystal are stacked in opposite directions.

8. The assembly method according to claim 7, characterized in that, After S4, it also includes: Place the pre-loaded sensor assembly into the vacuum brazing furnace and allow the pressure in the vacuum brazing furnace to be <10 -3 Pa; Using gold-nickel or silver-copper brazing filler metal, and raising the temperature inside the vacuum brazing furnace to above the melting point of the filler metal under vacuum conditions, a metallurgical bonding layer is formed between the pressure-transmitting diaphragm and the stainless steel shell, and between the electrode leads and the insulator.

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