Insulating mounting base for piezoelectric vibration sensor and method for manufacturing the same

Abstract

The application provides an insulating mounting base of a piezoelectric vibration sensor and a preparation method thereof, relates to the technical field of piezoelectric vibration sensors, and rigidly connects an insulating gasket between an upper seat and a lower seat in a fusion welding mode, realizes electrical insulation between the upper seat and the lower seat through the barrier of the insulating gasket, and realizes the rigid connection between the upper seat, the insulating gasket and the lower seat through a eutectic welding process combining an aluminum nitride ceramic copper-clad plate and a tin-silver-copper soldering sheet, so that the bonding strength of the bonding surface is high and the mechanical impact resistance is good. The upper seat of the insulating mounting base is fixed on the piezoelectric ceramic vibration sensor through screwing, and then the lower seat is fixed on the object to be tested through screwing, so that the rigid connection between the sensor and the object to be tested is realized, the GND crosstalk problem is solved, the structure is simple and compact, the cost is low, the use is convenient, the insulation effect is good, the rigid connection is realized, and the sensor output signal can be prevented from being disturbed.

Description

TECHNICAL FIELD

[0001] The present application relates to piezoelectric vibration sensor related technology, especially to a kind of piezoelectric vibration sensor insulating mounting base and preparation method thereof. BACKGROUND

[0002] Piezoelectric ceramic vibration sensor has the advantages of small size, light weight, high output sensitivity, good frequency response characteristics, etc., and is widely used in consumer electronics, industrial control, system monitoring, national defense and military fields.

[0003] The traditional fixed piezoelectric ceramic vibration sensor has the following two ways: the first is to use adhesive, generally using epoxy, resin and other adhesives to directly paste the sensor on the measured object. This method is easy to implement, simple and fast, but when the measured object has large vibration level and high test environment temperature, the sensor may fall off; and the adhesive is not a rigid connection, which will seriously affect the output accuracy of the sensor in high-precision measurement field; the second way is to use threaded rod to rigidly connect the sensor and the magnetic base, and the magnetic base is adsorbed on the measured object. This method is mainly used for large volume and ferromagnetic sensors. Therefore, for piezoelectric ceramic vibration sensors with small size, high measurement accuracy, large vibration level, high test environment temperature and insulation performance requirements, an effective and convenient installation method is urgently needed.

[0004] As shown in Figure 1 , the piezoelectric ceramic vibration sensor generally consists of a piezoelectric element 01, a shell 02, a mass block 03, a bolt 04, a base 05, a signal output end 06, etc. The piezoelectric element 01 and the mass block 03 are fixed on the base 05 by the bolt 04, when the mass block 03 is subjected to acceleration, it is converted into a force proportional to the acceleration and loaded on the piezoelectric material, and the piezoelectric material generates an electric charge signal proportional to the acceleration on its surface after being stressed, which is output externally through the signal output end.

[0005] As shown in Figure 1 , the base 05 acts as a negative electrode during the generation of the electric charge signal, and when the base 05 is directly connected to the test object, it will seriously affect the charge accumulation of the piezoelectric vibration sensor, and also produce ground signal crosstalk (GND crosstalk) to the test object. When there is slight displacement and deformation between the base 05 and the test object, the output accuracy of the piezoelectric vibration sensor will be affected. SUMMARY

[0006] The embodiment of the present application provides an insulating mounting base of a piezoelectric vibration sensor and a preparation method thereof, the prepared insulating mounting base has high strength, high precision and good insulation function, can realize high-precision signal transmission of the piezoelectric ceramic vibration sensor, reduces the influence of base deformation on sensor signal output and zero drift in the high-strength vibration process, and can also avoid GND crosstalk between a measured object and the sensor.

[0007] The first aspect of the embodiment of the present application provides a preparation method of an insulating mounting base of a piezoelectric vibration sensor, the insulating mounting base of the piezoelectric vibration sensor comprises an upper seat, an insulating gasket and a lower seat, wherein the insulating gasket is located between the upper seat and the lower seat, the insulating gasket and the upper seat and the lower seat are rigidly connected with each other in a fusion welding mode, the outer surfaces of the upper seat and the lower seat are provided with a nickel plating layer with a thickness of 3-10 mu m, and the preparation method of the insulating mounting base comprises the following steps:

[0008] Titanium alloy bars are used to make upper seat blank parts and lower seat blank parts through preforming treatment, wherein the upper seat blank parts and the lower seat blank parts are both in the shape of cylindrical bosses;

[0009] After surface pretreatment is performed on the upper seat blank parts and the lower seat blank parts, chemical nickel plating treatment is performed, the thickness of the nickel plating layer is controlled to be 3-10 mu m, and after the nickel plating treatment is completed, heat treatment at a temperature of 300-500 DEG C is directly performed;

[0010] Aluminum nitride ceramic copper-clad technology is used to directly heat aluminum nitride ceramic at a high temperature of 1000-1100 DEG C in a mixed gas environment of nitrogen and oxygen, then a copper foil layer with a thickness of 20 mu m-40 mu m is directly welded on the surface of the aluminum nitride ceramic, and an aluminum nitride ceramic copper-clad plate is formed;

[0011] A nickel-palladium-gold layer with a thickness of 1-3 mu m is formed on the surface of the aluminum nitride ceramic copper-clad plate by using high-temperature sintering nickel plating technology, and then a laser cutting process is used to form an insulating gasket with an octagonal structure;

[0012] The insulating gasket is placed between the lower surface of the upper seat blank part and the upper surface of the lower seat blank part, a layer of tin-silver-copper solder sheet is placed between the insulating gasket and the lower surface of the upper seat blank part, and a layer of tin-silver-copper solder sheet is placed between the insulating gasket and the upper surface of the lower seat blank part, and after the upper seat blank part, the insulating gasket, the lower seat blank part and the tin-silver-copper solder sheet are combined, a sandwich structure is formed;

[0013] The eutectic welding treatment technology is used to realize the fusion welding rigid connection between the upper seat blank part, the insulating gasket and the lower seat blank part in cooperation with the tin-silver-copper solder sheet;

[0014] A connecting thread is processed at the end of the upper seat blank and the lower seat blank, and then the insulating mounting base is prepared.

[0015] Optionally, the eutectic welding process cooperated with the tin-silver-copper solder sheet to realize the fusion welding rigid connection among the upper seat blank, the insulating gasket and the lower seat blank comprises:

[0016] The controllable atmosphere eutectic furnace is subjected to at least two times of vacuumizing and nitrogen filling reciprocating cycle pretreatment, and then the controllable atmosphere eutectic furnace is subjected to temperature rising preheating treatment;

[0017] The controllable atmosphere eutectic furnace is vacuumized, and then heated to a formic acid environment with a temperature 30-50℃ higher than the temperature at the end of the vacuumizing treatment, and the eutectic heat preservation welding treatment is performed, and the sandwich structure formed after the combination of the upper seat blank, the insulating gasket, the lower seat blank and the tin-silver-copper solder sheet is subjected to pressurization of 20g-40g during the eutectic heat preservation welding treatment;

[0018] After the eutectic heat preservation welding treatment is completed, the cooling treatment is performed, and after the room temperature is reached, the eutectic welding process cooperated with the tin-silver-copper solder sheet to realize the fusion welding rigid connection among the upper seat blank, the insulating gasket and the lower seat blank is completed.

[0019] Optionally, the thickness of the tin-silver-copper solder sheet in the sandwich structure formed after the combination of the upper seat blank, the insulating gasket, the lower seat blank and the tin-silver-copper solder sheet is 0.8mm-1.5mm, and the thickness of the insulating gasket is 1mm-1.5mm.

[0020] Optionally, the high-temperature sintering nickel plating process is used to form a layer of nickel-palladium-gold layer with a thickness of 1-3μm on the surface of the aluminum nitride ceramic copper-clad plate, which comprises:

[0021] The pretreated aluminum nitride ceramic copper-clad plate is placed in a quartz boat, and sintered at a peak temperature of 850-900℃ for 8-12min;

[0022] A layer of nickel-palladium-gold layer with a thickness of 1-3μm is formed on the upper and lower surfaces of the aluminum nitride ceramic copper-clad plate by using a thick film screen printing high-temperature sintering process.

[0023] Optionally, the pretreatment process of the aluminum nitride ceramic copper-clad plate comprises:

[0024] The deionized water, hydrochloric acid with a concentration of 37% and hydrogen peroxide are mixed in a volume ratio of 5:1:1 to prepare a cleaning solution, and then the aluminum nitride ceramic copper-clad plate is soaked in the cleaning solution and boiled for 1 hour;

[0025] Rinse the soaked aluminum nitride ceramic copper clad plate with deionized water at 50℃~70℃ for 30min~35min;

[0026] Submerge the rinsed aluminum nitride ceramic copper clad plate in anhydrous ethanol to dehydrate the aluminum nitride ceramic copper clad plate; then use a nitrogen gas gun to dry the aluminum nitride ceramic copper clad plate for standby.

[0027] Optionally, the thick film screen printing high-temperature sintering process includes:

[0028] Use a 250-mesh, 50-μm-thick latex polyester mesh to uniformly print the palladium-silver paste on the front surface of the aluminum nitride ceramic copper clad plate, and level the print for 5~10min;

[0029] Place the wet-film aluminum nitride ceramic copper clad plate on a mesh belt infrared drying oven, set the drying oven temperature to 120~150℃, and set the belt speed to 120mm / min, and dry for 25~30min;

[0030] After the palladium-silver paste on the front surface of the aluminum nitride ceramic copper clad plate is dried and solidified, use the same screen printing process described above to print a layer of palladium-silver paste on the back surface of the aluminum nitride ceramic copper clad plate, and use the infrared drying oven to dry and solidify;

[0031] Place the aluminum nitride ceramic copper clad plate printed with palladium-silver paste on both surfaces in a quartz boat, and place the quartz boat in a chain sintering furnace, and sinter at a peak temperature of 850~900℃ for 10~15min, and after sintering, form a layer of nickel-palladium-gold layer with a thickness of 1~3μm on the upper and lower surfaces of the aluminum nitride ceramic copper clad plate.

[0032] Optionally, the surface pretreatment of the upper seat blank and the lower seat blank before the chemical nickel plating treatment includes:

[0033] Sand blast the upper seat blank and the lower seat blank to increase the surface roughness thereof;

[0034] After sand blasting, clean the upper seat blank and the lower seat blank with an organic solvent, and then clean the upper seat blank and the lower seat blank with an inorganic solvent, and then perform chemical nickel plating treatment on the upper seat blank and the lower seat blank.

[0035] Optionally, the at least 2 times of vacuum pumping and nitrogen gas filling reciprocating cycle pretreatment of the controllable atmosphere eutectic furnace includes:

[0036] Perform the first vacuum pumping of the controllable atmosphere eutectic furnace at 0℃, and then perform the first nitrogen gas filling treatment, and during the first nitrogen gas filling, increase the temperature of the controllable atmosphere eutectic furnace to 60℃~80℃;

[0037] The controllable atmosphere eutectic furnace is subjected to a second nitrogen filling treatment after a second vacuumization at a temperature range of 60-80℃, and the temperature of the controllable atmosphere eutectic furnace is raised to 120-180℃ during the second nitrogen filling.

[0038] The controllable atmosphere eutectic furnace is maintained at a temperature range of 120-180℃ for a time length of 80-100s, and a third vacuumization of the controllable atmosphere eutectic furnace is realized during the time length.

[0039] The second aspect of the embodiment of the present application provides an insulating mounting base prepared by the preparation method of any one of the first aspect, the insulating mounting base being used for a piezoelectric vibration sensor, the insulating mounting base comprising an upper seat, an insulating gasket and a lower seat, wherein the insulating gasket is located between the upper seat and the lower seat, the insulating gasket and the upper seat and the lower seat are rigidly connected to each other in a fusion welding manner, the outer surfaces of the upper seat and the lower seat are provided with a nickel plating layer with a thickness of 3-10μm, the insulating gasket is an aluminum nitride ceramic copper-clad plate, and the upper surface and the lower surface of the aluminum nitride ceramic copper-clad plate are provided with a nickel-palladium-gold layer.

[0040] Optionally, the thickness of the insulating gasket is 1-1.5mm, and the thickness of the nickel-palladium-gold layer is 1-3μm.

[0041] The third aspect of the embodiment of the present application provides an electronic device, comprising:

[0042] a processor, a memory and a transmission interface for data transmission with the other device;

[0043] the memory stores computer execution instructions;

[0044] the processor executes the computer execution instructions stored in the memory to realize the method of any one of the first aspect.

[0045] The fourth aspect of the embodiment of the present application provides a computer storage medium, wherein computer program instructions are stored, the computer program instructions being used to realize the method of any one of the first aspect.

[0046] The application provides an insulating mounting base of a piezoelectric vibration sensor and a preparation method thereof, rigidly connecting an insulating gasket between the upper base and the lower base in a fusion welding manner, realizing electrical insulation between the upper base and the lower base through the barrier of the insulating gasket, and realizing rigid connection between the upper base, the insulating gasket and the lower base through a eutectic welding process of an aluminum nitride ceramic copper-clad plate combined with a tin-silver-copper soldering sheet, the bonding surface has high connection strength and good mechanical impact resistance, the upper base of the insulating mounting base is fixed on the piezoelectric ceramic vibration sensor through screwing, and then the whole sensor is fixed on the object to be tested through screwing of the lower base, rigid connection between the sensor and the object to be tested is realized through the fixing mode, the GND crosstalk problem is solved, the structure is simple and compact, the cost is low, the use is convenient, the insulation effect is good, rigid connection is realized, the sensor output signal can be prevented from being disturbed, and reliable work of the sensor in a high-impact high-vibration scene can be met. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 A structure diagram of a piezoelectric vibration sensor provided by the prior art is shown in the figure.

[0048] Figure 2 A structure diagram of the upper base blank and the lower base blank provided by the application is shown in the figure.

[0049] Figure 3 A structure diagram of the insulating gasket provided by the application is shown in the figure.

[0050] Figure 4 A eutectic welding process provided by the application is shown in the figure.

[0051] Figure 5 A structure diagram of the insulating mounting base provided by the application is shown in the figure.

[0052] Figure 6 A use diagram of the insulating mounting base provided by the application is shown in the figure. DETAILED DESCRIPTION

[0053] To make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application, obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0054] The terms "first", "second", "third", "fourth" and the like in the description and in the claims of the present application, and above-mentioned drawings, if any, are used to distinguish between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the use of the terms so construed can be interchanged, under appropriate circumstances, to describe the embodiments of the present application herein described with other than the described or illustrated order, or uses.

[0055] It should be understood that, in various embodiments of the present application, the magnitude of the serial number of each process does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0056] It should be understood that in the present application, "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0057] It should be understood that in the present application, "a plurality of" means two or more. "And / or" is only a description of the relationship between the associated objects, which means that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after are in an "or" relationship. "Including A, B and C", "including A, B, C" means that A, B and C are all included, "including A, B or C" means that one of A, B and C is included, and "including A, B and / or C" means that any one or any two or three of A, B and C is included.

[0058] It should be understood that in the present application, "B corresponding to A", "B corresponding to A", "A corresponding to B" or "B corresponding to A" means that B is associated with A, and B can be determined according to A. Determining B according to A does not mean that B is determined only according to A, but also can be determined according to A and / or other information. The matching of A and B means that the similarity of A and B is greater than or equal to a preset threshold.

[0059] Depending on the context, "if" as used herein can be interpreted as "when" or "while" or "in response to determining" or "in response to detecting".

[0060] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0061] ReferenceFigure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown in the drawings, the application provides a preparation method of an insulating mounting base of a piezoelectric vibration sensor, and the insulating mounting base of the piezoelectric vibration sensor prepared by the preparation method comprises an upper seat 1, an insulating gasket 2 and a lower seat 3, wherein the insulating gasket 2 is located between the upper seat 1 and the lower seat 3, the insulating gasket 2 and the upper seat 1 and the lower seat 3 are rigidly connected by fusion welding, and the outer surfaces of the upper seat 1 and the lower seat 3 are provided with a nickel plating layer of 3-10 μm. The preparation method of the insulating mounting base provided by the embodiment of the application comprises:

[0062] Step 100: titanium alloy bar materials are used to make upper seat blank and lower seat blank by preforming treatment, wherein, as shown in the drawings, the upper seat blank and the lower seat blank are both in the shape of a cylindrical boss. Figure 2 As shown in the drawings, the materials of the upper seat and the lower seat are selected from titanium alloy bar materials, and the upper seat and the lower seat are processed on a horizontal milling machine, as shown in the drawings, the upper seat blank and the lower seat blank in the shape of a cylindrical boss are formed.

[0063] Figure 2 As shown in the drawings, the materials of the upper seat and the lower seat are selected from titanium alloy bar materials, and the upper seat and the lower seat are processed on a horizontal milling machine, as shown in the drawings, the upper seat blank and the lower seat blank in the shape of a cylindrical boss are formed. Figure 2

[0064] Step 110: after the surface pretreatment of the upper seat blank and the lower seat blank, chemical nickel plating treatment is performed, the thickness of the nickel plating layer is controlled to be 3-10 μm, and after the nickel plating treatment is completed, heat treatment at 300-500 ℃ is directly performed.

[0065] Specifically, first, the upper seat blank and the lower seat blank are subjected to sand blasting treatment to improve the surface roughness thereof; after the sand blasting treatment, the upper seat blank and the lower seat blank are cleaned with organic solvent, and then cleaned with inorganic solvent, and then the upper seat blank and the lower seat blank are subjected to chemical nickel plating treatment.

[0066] The embodiment of the application forms a layer of weldable nickel on the surfaces of the upper seat and the lower seat made of titanium alloy by chemical nickel plating treatment process, thereby improving the weldability of the surfaces of the upper seat and the lower seat made of titanium alloy, and in order to improve the adhesion of the nickel plating layer on the surfaces of the upper seat and the lower seat, first, the upper seat blank and the lower seat blank are subjected to sand blasting treatment to improve the surface roughness thereof; then the upper seat blank and the lower seat blank are cleaned with organic solvent and then cleaned with inorganic solvent, so that the surfaces of the upper seat blank and the lower seat blank are cleaned, and then chemical nickel plating treatment is performed, the thickness of the nickel plating layer is controlled to be 3-10 μm; after the nickel plating is completed, the embodiment of the application adds heat treatment process at 300-500 ℃ to accelerate the diffusion of the nickel plating layer on the surface of titanium alloy, so as to form stronger interface bonding capacity.

[0067] ​​Step 120: Directly heat the aluminum nitride ceramic in a mixed gas environment of nitrogen and oxygen at a high temperature of 1000-1100℃ by using an aluminum nitride ceramic copper clad process, and then directly weld a copper foil layer with a thickness of 20-40μm on the surface of the aluminum nitride ceramic, thereby forming an aluminum nitride ceramic copper clad plate.

[0068] Step 130: Form a nickel-palladium-gold layer 4 with a thickness of 1-3μm on the surface of the aluminum nitride ceramic copper clad plate by using a high-temperature sintering nickel plating process, and then form an octagonal structure of the insulating gasket by using laser cutting.

[0069] Specifically, the pretreated aluminum nitride ceramic copper clad plate is placed in a quartz boat, and sintered at a peak temperature of 850-900℃ for 8-12min; a thick film screen printing high-temperature sintering process is used to sinter a nickel-palladium-gold layer with a thickness of 1-3μm on the upper and lower surfaces of the aluminum nitride ceramic copper clad plate.

[0070] First, the deionized water, 37% hydrochloric acid and hydrogen peroxide are mixed in a volume ratio of 5:1:1 to prepare a cleaning solution, and then the aluminum nitride ceramic copper clad plate is soaked in the cleaning solution and boiled for 1 hour; the soaked aluminum nitride ceramic copper clad plate is washed with deionized water at 50-70℃ for 30-35min; the washed aluminum nitride ceramic copper clad plate is soaked in anhydrous ethanol to dehydrate the aluminum nitride ceramic copper clad plate; and then the aluminum nitride ceramic copper clad plate is blown dry with a nitrogen gas gun for standby.

[0071] Then, the palladium-silver paste is uniformly printed on the front surface of the aluminum nitride ceramic copper clad plate by using a 250-mesh, 50μm-thick polyester mesh, and leveled for 5-10min after printing; the wet film aluminum nitride ceramic copper clad plate is placed on a mesh belt infrared drying oven, the drying oven temperature is set to 120-150℃, the belt speed is 120mm / min, and the drying time is 25-30min; after the palladium-silver paste on the front surface of the aluminum nitride ceramic copper clad plate is dried and solidified, the same screen printing process is used to print a layer of palladium-silver paste on the back surface of the aluminum nitride ceramic copper clad plate, and the infrared drying oven is also used for drying and solidification; the aluminum nitride ceramic copper clad plate with palladium-silver paste printed on both sides is placed in a quartz boat, and the quartz boat is placed in a chain sintering furnace, sintered at a peak temperature of 850-900℃ for 10-15min, and a nickel-palladium-gold layer with a thickness of 1-3μm is formed on the upper and lower surfaces of the aluminum nitride ceramic copper clad plate after sintering.

[0072] The insulating gasket 2 of the embodiment of the present application is selected from aluminum nitride ceramic copper clad plate, and a direct copper clad process (DBC) is adopted to heat at a high temperature of about 1063 DEG C in nitrogen containing oxygen, so as to directly weld a copper foil on the surface of the aluminum nitride ceramic. The embodiment of the present application innovatively utilizes the copper-oxygen eutectic liquid phase formed during sintering of copper and oxygen to wet the surfaces of the two materials in contact, i.e. the surface of the copper foil and the surface of the ceramic, and also reacts with aluminum oxide to generate CuAlO2, Cu(AlO2)2 and other composite oxides, which serve as solder for eutectic brazing, and innovatively realizes firm combination of the copper foil and the ceramic. Since the aluminum nitride is a non-oxide ceramic, the key to cladding the copper foil is to form an oxide transition layer on the surface thereof, and then realize cladding of the AlN and the copper foil through the above-mentioned transition layer and the Cu foil. After the aluminum nitride copper clad plate is manufactured, a layer of nickel-palladium-gold with a thickness of 1-3 microns is electroplated on the surface thereof to increase the weldability, and finally laser cutting is performed to manufacture the octagonal insulating gasket as shown in Figure 3 The thickness of the insulating gasket is 1-1.5 mm.

[0073] Step 140: placing the insulating gasket between the lower surface of the upper seat blank and the upper surface of the lower seat blank, and placing a layer of tin-silver-copper soldering sheet between the insulating gasket and the lower surface of the upper seat blank and between the insulating gasket and the upper surface of the lower seat blank, so that the upper seat blank, the insulating gasket, the lower seat blank and the tin-silver-copper soldering sheet form a sandwich structure.

[0074] Specifically, the embodiment of the present application cuts the tin-silver-copper soldering sheet (SAC305 soldering sheet with a thickness of 1 mm) for eutectic welding according to the size of the insulating gasket, wherein the size of the tin-silver-copper soldering sheet is smaller than the size of the ceramic substrate, and such arrangement can ensure high rigid connection strength after eutectic welding and prevent the tin-silver-copper soldering sheet from being exposed. The cut tin-silver-copper soldering sheet is cleaned with deionized water, then cleaned with ultrasonic waves in an ethanol solution, and finally dried for standby use. Then the lower seat blank is placed in a special eutectic welding tool, a piece of cut tin-silver-copper soldering sheet is placed on the front surface of the lower seat blank, then the insulating gasket is placed, a piece of cut tin-silver-copper soldering sheet is placed on the front surface of the insulating gasket, and finally the upper seat blank is placed; the upper seat blank, the lower seat blank, the tin-silver-copper soldering sheet and the insulating gasket are stacked to form a "sandwich" structure through the tool, and such arrangement can improve the connection rigidity after fusion welding of the upper seat, the lower seat and the insulating gasket.

[0075] The thickness of the tin-silver-copper solder sheet in the sandwich structure formed by combining the upper seat blank, the insulating gasket, the lower seat blank and the tin-silver-copper solder sheet is 0.8mm-1.5mm, and the thickness of the insulating gasket is 1mm-1.5mm, and the eutectic welding process can ensure the connection rigidity and reliability between the upper seat, the lower seat and the insulating gasket.

[0076] Step 150: The eutectic welding process is used to realize the fusion welding rigid connection between the upper seat blank, the insulating gasket and the lower seat blank.

[0077] Specifically, the controllable atmosphere eutectic furnace is subjected to at least two times of vacuum pumping and nitrogen filling reciprocating cycle pretreatment to discharge oxygen and water vapor in the controllable atmosphere eutectic furnace, and then the controllable atmosphere eutectic furnace is subjected to temperature preheating treatment; the embodiment of the application reduces the oxygen and water vapor content in the furnace by pretreatment during vacuum eutectic welding, thereby improving the structural strength and reliability of eutectic welding. The controllable atmosphere eutectic furnace is pumped to a vacuum environment, and then heated to a formic acid environment with a temperature higher than the temperature at the end of the vacuum pumping treatment by 30-50℃ for eutectic holding welding treatment, and the sandwich structure formed by combining the upper seat blank, the insulating gasket, the lower seat blank and the tin-silver-copper solder sheet is subjected to pressure of 20g-40g during the eutectic holding welding treatment. After the eutectic holding welding treatment is completed, the cooling treatment is performed, and the fusion welding rigid connection process between the upper seat blank, the insulating gasket and the lower seat blank is completed by using the eutectic welding process with the tin-silver-copper solder sheet.

[0078] In the first vacuum pumping of the controllable atmosphere eutectic furnace at 0℃, the first nitrogen filling treatment is performed, and the temperature of the controllable atmosphere eutectic furnace is raised to 60-80℃ during the first nitrogen filling; the second vacuum pumping of the controllable atmosphere eutectic furnace at 60-80℃ is performed, and the second nitrogen filling treatment is performed, and the temperature of the controllable atmosphere eutectic furnace is raised to 120-180℃ during the second nitrogen filling; the controllable atmosphere eutectic furnace is maintained at a temperature environment of 120-180℃ for a time length of 80-100s, and the third vacuum pumping of the controllable atmosphere eutectic furnace is realized during this period.

[0079] Reference Figure 4As shown, in the pre-treatment stage, the controllable atmosphere eutectic furnace is subjected to at least two times of vacuum pumping and nitrogen filling reciprocating cycles to discharge oxygen and water vapor in the controllable atmosphere eutectic furnace. That is, in the interval of t1~t5 (for example, t1= t2= t3= t4= t5= 60~100s), the controllable atmosphere eutectic furnace is subjected to at least two times of vacuum pumping and nitrogen filling reciprocating cycles to discharge oxygen and water vapor in the controllable atmosphere eutectic furnace, and finally form an inert protective atmosphere of nitrogen in the welding furnace chamber to prevent oxidation of the tin-silver-copper solder sheet (SAC305 solder sheet). In the process of the first nitrogen filling, the temperature of the controllable atmosphere eutectic furnace is raised to 60~80℃ (θ1 platform); after the second vacuum pumping of the controllable atmosphere eutectic furnace in the temperature range of 60~80℃, the second nitrogen filling treatment is carried out, and in the process of the second nitrogen filling, the temperature of the controllable atmosphere eutectic furnace is raised to 120~180℃ (θ2 platform); and in the temperature environment of 120~180℃, the third vacuum pumping treatment of the controllable atmosphere eutectic furnace is realized for a time length of 80s~100s. At the θ2 platform temperature, the upper seat, the insulating gasket, the lower seat, the SAC305 solder sheet, the welding tooling, etc. are preheated for about 90s.

[0080] Reference Figure 4 As shown, in the welding stage, in the interval of t6~t7 (for example, t6=t7=90~120s), the temperature is raised to 240~260℃ (θ3 platform) to reach above 30~50℃ of the melting point temperature (217℃) of the SAC305 solder sheet; at the same time, the atmosphere of formic acid is provided during the welding process, so that the SAC305 solder sheet is fully melted, and the upper seat, the insulating gasket, and the lower seat of the "sandwich" structure are simultaneously subjected to a pressure of 20g~40g by using the tooling clamp during the solder sheet melting process, so as to realize reliable welding between the upper seat, the insulating gasket, and the lower seat. In the cooling stage, in the interval of t8 (120~180s), nitrogen is blown into the controllable atmosphere eutectic furnace chamber to reduce the furnace chamber temperature to below 217℃, so as to realize cooling and solidification of the SAC305 solder sheet, so as to rigidly weld the upper seat, the insulating gasket, and the lower seat together.

[0081] The preparation method of the insulating mounting base provided by the embodiment of the application reduces the oxygen and water vapor content in the air in the furnace through the reciprocating cycle of vacuum extraction and nitrogen filling in the eutectic welding process, avoids the oxidation of the solder alloy in the eutectic process, and ensures that the surface to be welded is uniformly heated to the welding temperature and then is heat treated for welding; the controllable atmosphere eutectic furnace is used, formic acid is used as a reducing agent and a flux, and a tin-silver-copper solder sheet (SAC305 solder sheet) is used to replace the traditional solder paste to perform eutectic welding between the upper seat, the insulating gasket and the lower seat, the formic acid environment is matched with the tin-silver-copper solder sheet to control the temperature and time in the welding process, and the welding quality is greatly improved, so that the bonding surface after welding can withstand a 5000g mechanical impact test.

[0082] Step 160: threads are machined at the ends of the upper seat blank and the lower seat blank, respectively, and then the insulating mounting base is prepared.

[0083] The insulating mounting base of the piezoelectric vibration sensor and the preparation method thereof provided by the application rigidly connect an insulating gasket between the upper seat and the lower seat by means of fusion welding, realize electrical insulation between the upper seat and the lower seat through the blocking of the insulating gasket, and realize the fusion welding rigid connection between the upper seat, the insulating gasket and the lower seat by means of the eutectic welding process of the aluminum nitride ceramic copper-clad plate combined with the tin-silver-copper solder sheet, the bonding strength is high and the mechanical impact resistance is good, the upper seat of the insulating mounting base is fixed on the piezoelectric ceramic vibration sensor through threads, and then the whole sensor is fixed on the object to be tested through the lower seat threads; through the installation and fixation in this way, the rigid connection between the sensor and the object to be tested can be realized, and the GND crosstalk problem can be solved, the structure is simple and compact, the cost is low, the use is convenient, the insulation effect is good, the rigid connection can be achieved, the sensor output signal can be prevented from being disturbed, and the reliable work of the sensor in a high-impact high-vibration scene can be met.

[0084] Reference Figure 5 and Figure 6As shown, the insulating mounting base prepared by the insulating mounting base of the embodiment of the application is used for the piezoelectric vibration sensor 5, and the insulating mounting base comprises an upper seat 1, an insulating gasket 2 and a lower seat 3, wherein the insulating gasket 2 is located between the upper seat 1 and the lower seat 3, the insulating gasket 2 and the upper seat 1 and the lower seat 3 are rigidly connected with each other by means of fusion welding, the outer surfaces of the upper seat 1 and the lower seat 3 are provided with a nickel plating layer of 3-10 mu m, the insulating gasket 2 is made of aluminum nitride ceramic copper-clad plate, and the upper surface and the lower surface of the aluminum nitride ceramic copper-clad plate are provided with a nickel-palladium-gold layer, the thickness of the insulating gasket 2 is 1 mm-1.5 mm, and the thickness of the nickel-palladium-gold layer is 1 mu m-3 mu m. The upper seat of the insulating mounting base is fixed on the piezoelectric ceramic vibration sensor by screwing, and then the whole sensor is fixed on the object to be tested by screwing the lower seat; through the installation and fixation in this way, not only the rigid connection between the sensor and the object to be tested can be realized, but also the GND crosstalk problem can be solved, which is not only simple in structure, low in cost, convenient to use, good in insulating effect, but also can realize rigid connection, prevent the sensor output signal from being interfered, and meet the reliable work of the sensor in the high-impact and high-vibration scene.

[0085] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing an insulating mounting base for a piezoelectric vibration sensor, characterized in that, The insulating mounting base of the piezoelectric vibration sensor includes an upper base, an insulating pad, and a lower base. The insulating pad is located between the upper base and the lower base. The insulating pad and the upper and lower bases are rigidly connected to each other by fusion welding. The outer surfaces of the upper and lower bases are provided with a 3-10 μm nickel plating layer. The method for preparing the insulating mounting base includes: The upper and lower seat blanks are made by preforming titanium alloy bars, wherein both the upper and lower seat blanks are cylindrical bosses. After surface pretreatment of the upper and lower blanks, chemical nickel plating is performed, with the nickel plating layer thickness controlled at 3~10μm. After the nickel plating is completed, heat treatment at 300~500℃ is performed directly. The aluminum nitride ceramic copper clad board is formed by heating the aluminum nitride ceramic at a high temperature of 1000~1100℃ in a mixed gas environment of nitrogen and oxygen, and then welding a copper foil layer with a thickness of 20μm~40μm directly onto the surface of the aluminum nitride ceramic. A nickel-palladium-gold layer with a thickness of 1~3μm is formed on the surface of aluminum nitride ceramic copper-clad laminate by high-temperature sintering nickel plating process, and then an octagonal insulating pad is formed by laser cutting. An insulating pad is placed between the lower surface of the upper blank and the upper surface of the lower blank, and a tin-silver-copper solder sheet is placed between the insulating pad and the lower surface of the upper blank, and a tin-silver-copper solder sheet is placed between the insulating pad and the upper surface of the lower blank. The upper blank, the insulating pad, the lower blank and the tin-silver-copper solder sheet are combined to form a sandwich-like structure. A eutectic welding process is used in conjunction with the tin-silver-copper solder sheet to achieve a rigid fusion weld connection between the upper blank, the insulating pad, and the lower blank; Connecting threads are machined at the ends of the upper and lower blanks respectively, and then the insulating mounting base is obtained. The process of forming a 1-3 μm thick nickel-palladium-gold layer on the surface of the aluminum nitride ceramic copper-clad laminate using a high-temperature sintering nickel plating process includes: The pretreated aluminum nitride ceramic copper-clad plate was placed in a quartz boat and sintered at a peak temperature of 850℃~900℃ for 8min~12min. A nickel-palladium-gold layer with a thickness of 1~3μm is formed on the upper and lower surfaces of an aluminum nitride ceramic copper-clad laminate by using a thick film screen printing high-temperature sintering process. The process of forming a 1-3 μm thick nickel-palladium-gold layer on the upper and lower surfaces of the aluminum nitride ceramic copper-clad laminate using a thick-film screen printing and high-temperature sintering process includes: Palladium silver paste was uniformly printed onto the front side of aluminum nitride ceramic copper-clad board using a 250-mesh polyester screen with a latex thickness of 50μm. After printing, the leveling process took 5-10 minutes. The wet film aluminum nitride ceramic copper-clad plate was placed on a mesh belt infrared drying oven. The oven temperature was set to 120~150℃, the belt speed was 120mm / min, and the drying time was 25~30min. After the palladium-silver paste on the front side of the aluminum nitride ceramic copper-clad laminate is dried and cured, a layer of palladium-silver paste is printed on the back side of the aluminum nitride ceramic copper-clad laminate using the same screen printing process described above, and then dried and cured using an infrared drying oven. The aluminum nitride ceramic copper-clad laminate, after double-sided printing of palladium-silver paste, is placed in a quartz boat, which is then placed in a chain sintering furnace and sintered at a peak temperature of 850~900℃ for 10~15 minutes. After sintering, a nickel-palladium-gold layer with a thickness of 1~3μm is formed on the upper and lower surfaces of the aluminum nitride ceramic copper-clad laminate.

2. The method for preparing an insulating mounting base according to claim 1, characterized in that, The method of using eutectic welding process in conjunction with tin-silver-copper solder sheets to achieve a rigid fusion weld connection between the upper blank, the insulating gasket, and the lower blank includes: The controlled atmosphere eutectic furnace is subjected to at least two cycles of vacuuming and nitrogen purging pretreatment, followed by a heating preheating treatment. The controlled atmosphere eutectic furnace is evacuated to a vacuum environment, and then heated to a formic acid environment at a temperature 30-50°C higher than the temperature at the end of the vacuuming process for eutectic heat preservation welding. During the eutectic heat preservation welding process, the sandwich-like structure formed by the combination of the upper blank, the insulating gasket, the lower blank and the tin-silver-copper solder sheet is pressurized by 20g-40g. After the eutectic insulation welding process is completed, a cooling process is carried out. After the temperature drops to room temperature, the rigid connection process between the upper blank, the insulating pad, and the lower blank is achieved by using the eutectic welding process in conjunction with the tin-silver-copper solder sheet.

3. The method for preparing an insulating mounting base according to claim 1, characterized in that, In the sandwich-like structure formed by combining the upper blank, the insulating pad, the lower blank, and the tin-silver-copper solder sheet, the thickness of the tin-silver-copper solder sheet is 0.8mm~1.5mm, and the thickness of the insulating pad is 1mm~1.5mm.

4. The method for preparing an insulating mounting base according to claim 3, characterized in that, The pretreatment process for the aluminum nitride ceramic copper-clad laminate includes: A cleaning solution was prepared by mixing deionized water, 37% hydrochloric acid, and hydrogen peroxide in a volume ratio of 5:1:

1. The aluminum nitride ceramic copper-clad laminate was then immersed in the cleaning solution and boiled for 1 hour. Rinse the aluminum nitride ceramic copper-clad laminate soaked in deionized water at 50℃~70℃ for 30min~35min; After rinsing, the aluminum nitride ceramic copper-clad board is immersed in anhydrous ethanol to dehydrate it; then, it is dried with a nitrogen gas gun for later use.

5. The method for preparing an insulating mounting base according to claim 4, characterized in that, The process of performing electroless nickel plating after surface pretreatment of the upper and lower blanks includes: The upper and lower blanks are sandblasted to improve their surface roughness. After sandblasting, the upper and lower blanks are cleaned with organic solvents, and then cleaned with inorganic solvents. Finally, the upper and lower blanks are chemically nickel-plated.

6. The method for preparing an insulating mounting base according to claim 2, characterized in that, The pretreatment of the controlled atmosphere eutectic furnace by at least two cycles of vacuuming and nitrogen purging includes: After the first vacuuming of the controlled atmosphere eutectic furnace at 0°C, the first nitrogen purging process is carried out, and the temperature of the controlled atmosphere eutectic furnace is raised to 60°C~80°C during the first nitrogen purging process. After the controlled atmosphere eutectic furnace is evacuated for the second time within a temperature range of 60℃ to 80℃, it is then purged with nitrogen for the second time. During the second nitrogen purging process, the temperature of the controlled atmosphere eutectic furnace is raised to 120℃ to 180℃. The temperature is maintained at 120℃~180℃ for 80s~100s, during which the third vacuuming process of the controllable atmosphere eutectic furnace is carried out.

7. An insulating mounting base prepared by the preparation method according to any one of claims 1 to 6, the insulating mounting base being used for a piezoelectric vibration sensor, characterized in that, The insulating mounting base includes an upper base, an insulating pad, and a lower base. The insulating pad is located between the upper base and the lower base. The insulating pad and the upper base and the lower base are rigidly connected to each other by fusion welding. The outer surfaces of the upper base and the lower base are provided with a nickel plating layer of 3~10μm. The insulating pad is made of aluminum nitride ceramic copper-clad laminate, and both the upper and lower surfaces of the aluminum nitride ceramic copper-clad laminate are provided with nickel palladium gold layers.

8. The insulating mounting base according to claim 7, characterized in that, The thickness of the insulating pad is 1mm to 1.5mm, and the thickness of the nickel-palladium-gold layer is 1μm to 3μm.

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