Quartz base planar differential type quartz beam accelerometer and packaging method thereof

Abstract

The application belongs to the technical field of inertial devices, and particularly relates to a quartz base planar differential quartz vibrating beam accelerometer and a packaging method thereof. The accelerometer comprises a shell, a circuit board, VIA chips, a quartz substrate and conductive pins. The inside of the shell is a vacuum cavity. The quartz substrate is composed of a quartz body, a rectangular step and a solder film. The rectangular step is used for positioning and fixing the VIA chips. The solder film realizes the soldering connection of the chips. Two VIA chips output positive and negative signals through differential detection. The circuit board provides driving signals for the chips and amplifies the output signals. The conductive pins transmit signals and receive control signals to regulate the working state of the chips. Through the vacuum cavity design, the differential detection technology, the high-precision assembly method and the reliable packaging process, the application solves the instability caused by the mismatch of the adhesive process and the thermal expansion coefficient and the performance problem affected by the assembly error in the prior art, and improves the measurement accuracy, the anti-interference ability and the assembly stability of the accelerometer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inertial devices, and particularly relates to a quartz base planar differential quartz vibrating beam accelerometer and a packaging method thereof. BACKGROUND

[0002] A quartz vibrating beam accelerometer is a high-precision sensor that measures acceleration using the piezoelectric effect and elastic properties of quartz material. It is considered a key development direction for the next generation of high-performance accelerometers due to its direct frequency output, high precision, small size, low cost, and all-solid-state advantages. It can measure the acceleration of an object in a certain direction and is commonly used in inertial navigation systems, attitude control, motion monitoring, and other fields. The high sensitivity and low drift characteristics of the quartz vibrating beam accelerometer make it a core component in high-precision inertial navigation systems such as aviation, aerospace, and submarine navigation. It can also be used for vibration monitoring and diagnosis of industrial equipment and machinery to detect abnormal conditions and prevent failures. In the field of aerospace, it is used to monitor and adjust the attitude of aircraft and satellites to ensure their trajectory and position stability. It can also be used for health monitoring of large structures such as bridges and buildings to analyze their acceleration response under external environmental conditions such as earthquakes and wind loads.

[0003] Compared with the widely used quartz flexible accelerometer, the quartz vibrating beam accelerometer has the characteristic of direct frequency output, which does not require the use of an IF board (Intermediate Frequency Board) for signal processing systems, especially in electronic instruments and communication equipment for processing intermediate frequency signals. This simplifies the structure and reduces the cost. At the same time, it has excellent performance, with a maximum precision of 0.1 μg and a batch production precision of 10 μg, making it a potential strategic level accelerometer and achieving mass production of navigation level accelerometers. In addition, the quartz vibrating beam accelerometer chip is made using a wet etching process, which has the advantages of low cost and batch production, and can be further miniaturized and microfabricated by combining modern microfabrication technology.

[0004] The mainstream product structure of the current quartz vibrating beam accelerometer is a cylindrical barrel design, which includes quartz chips, TO bases (Transistor Outline Base), conductive support columns, vacuum packaging structures, and circuit boards. The quartz chip is the core component of the quartz vibrating beam accelerometer. The current mainstream chip assembly method usually uses a glue bonding process to fix the chip on the TO base, and then connects the two TO bases to the conductive support column. The main material of the TO base is metal, and the four conductive support columns are connected to the chip and the TO base using a ceramic sealing process to form the assembly.

[0005] However, such a traditional design has large performance fluctuations, poor stability, low long-term reliability and other problems. There is little fundamental solution to the above problems in existing literature and research, therefore, an innovative technical solution is urgently needed to fundamentally improve the performance and reliability of the quartz vibrating beam accelerometer, while reducing production costs and promoting its application in a wider range. SUMMARY

[0006] The present application is directed to the defects of the prior art, and proposes a quartz base planar differential quartz vibrating beam accelerometer and a packaging method thereof, which can solve the stress and process consistency problems caused by the gluing of the chip and the TO base, and realize low-stress and batch chip welding. The quartz base maintains the same thermal expansion coefficient as the chip, which can improve the high-low temperature characteristics and impact resistance. The planar differential structure design and assembly of high precision and miniaturization are realized.

[0007] In one aspect, the present application provides a packaging method of a quartz base planar differential quartz vibrating beam accelerometer, which comprises a box and a tube shell that are buckled together, and a circuit board, a VIA chip, a quartz substrate and a conductive pin arranged inside the box and the tube shell. The quartz substrate comprises a quartz body, a rectangular step and a solder film, wherein the rectangular steps are spaced apart on the quartz body and used for positioning and fixing the VIA chip; the solder film is plated on the rectangular step and used for realizing the soldering connection of the VIA chip; the packaging method comprises:

[0008] Step 1: pretreat the surface of the rectangular step of the quartz substrate, and plate a solder film on the surface of the rectangular step;

[0009] Step 2: initially place two VIA chips on the rectangular step of the quartz substrate, and use a micromechanical adjustment tool to accurately adjust the position of the VIA chips;

[0010] Step 3: heat the assembly formed by the quartz substrate and the VIA chips to the melting point temperature of the solder at a set heating rate, and then slowly cool down at a set cooling rate after maintaining for a certain time, so as to realize the soldering of the quartz substrate and the VIA chips;

[0011] Step 4: install the assembly formed by the soldered quartz substrate and the VIA chips to the middle region of the tube shell;

[0012] Step 5: bond the circuit board to the two ends of the quartz substrate, respectively;

[0013] Step 6: install the conductive pin to the tube shell, and electrically connect the circuit board to the conductive pin through the metal electrode and the VIA chip;

[0014] Step 7: A box cover is arranged above the tube shell, vacuum packaging is performed, and after welding is completed, vacuum leakage testing, mechanical performance testing, and electromagnetic shielding testing are sequentially performed.

[0015] In the preferred implementation, further, in step 1, the process of plating the solder film includes:

[0016] The rectangular step surface of the quartz substrate is activated by plasma cleaning or chemical cleaning to remove the surface oxide layer and particulate impurities;

[0017] The solder film is prepared by a magnetron sputtering or evaporation process: a magnetron sputtering process is used, the working gas pressure is controlled at 0.5-1.0 Pa, the sputtering power is controlled at 150 W-300 W, and the sputtering rate is adjusted to 0.1 μm / min; or an evaporation process is used, the heating temperature is controlled below the melting point of the solder alloy, and the vacuum degree is maintained at 10 -5 Torr;

[0018] During the magnetron sputtering or evaporation process, the film thickness is monitored in real time by a quartz crystal microbalance or a quartz crystal oscillation film thickness meter, the film thickness is accurately monitored, and the thickness of the solder film is accurately controlled within the range of 1 μm-100 μm, with a thickness deviation of ≤5%.

[0019] In the preferred implementation, further, in step 1, the solder film is composed of a metal alloy base, a wetting enhancer, an antioxidant, and a conductive enhancer; the metal alloy base is one of gold-tin alloy, indium-tin alloy, bismuth-tin alloy, silver-tin alloy, and indium-bismuth-tin alloy, but is not limited thereto; the wetting enhancer includes one of titanium, chromium, zirconium, nickel, and molybdenum, but is not limited thereto. The antioxidant includes one of palladium, iridium, platinum, rhenium, and manganese, but is not limited thereto. The conductive enhancer includes one of silver, copper, tungsten, and zinc, but is not limited thereto.

[0020] In the preferred implementation, further, in step 2, the parallelism deviation of the two VIA chips is ≤5 μm, and the positioning accuracy deviation is ≤100 μm.

[0021] In the preferred implementation, further, in step 3, the soldering process of the VIA chip and the quartz substrate includes: under the condition of a vacuum degree of 10 -6 Torr, the solder film on the rectangular step surface of the quartz substrate is uniformly heated to the melting point temperature range of the solder at a heating rate of ≤5 ℃ / min by using a precision temperature-controlled hot plate or an infrared heating system or a laser heater; the solder film is maintained at the melting point temperature range for 5-10 minutes to ensure that the solder is completely melted and fully combined with the VIA chip and the quartz substrate to form a stable soldering interface; after soldering is completed, the soldering area is slowly cooled at a cooling rate of ≤5 ℃ / min.

[0022] In the preferred implementation, further, in step 4, the combined quartz substrate and VIA chip assembly is mounted to the middle region of the tube shell using low outgassing rate vacuum glue or metal solder; in step 5, the circuit board is bonded to both ends of the quartz substrate using low outgassing rate vacuum glue or metal solder.

[0023] In the preferred implementation, further, in step 6, the circuit board and VIA chip are connected to the conductive pins through metal electrodes using gold wire bonding or precision welding process.

[0024] In the preferred implementation, further, in step 7, the vacuum packaging adopts any one of vacuum laser welding, eutectic welding and brazing welding process.

[0025] In another aspect, the application also provides a quartz base planar differential quartz vibration beam accelerometer, which is prepared by the packaging method as described in any one of the above.

[0026] In the preferred implementation, further, the inside of the box and the tube shell clamped together is a vacuum cavity; the two VIA chips output positive and negative signals respectively through differential detection; one side of each VIA chip is provided with a circuit board, which includes a driving circuit and an amplification circuit, and the driving circuit and the amplification circuit are connected with the metal electrodes of the corresponding VIA chip; the circuit board is used to provide driving signals for the VIA chip, and receive and amplify the output signals of the VIA chip; the outer side of each circuit board is provided with a conductive pin, which is embedded on the tube shell, and the conductive pin is used to transmit the processed signals of the circuit board to external equipment and receive control signals from external equipment to regulate the working state of the VIA chip.

[0027] The application has the following beneficial effects:

[0028] Firstly, the assembly method provided by the application ensures the high-precision positioning and stable connection of the VIA chip by pre-treating the rectangular stepped surface of the quartz substrate and plating a solder film, reduces internal stress and welding defects by using a welding process with a set temperature rising rate, thereby improving the mechanical stability and long-term reliability of the assembly. During the assembly process, microscopic mechanical adjustment tools and precise electrical connection process are used to ensure that the signal transmission path between the VIA chip and the circuit board and the conductive pin is stable and has low loss. The vacuum packaging process of the box and the tube shell, combined with strict test procedures, further optimizes the vacuum sealing performance and anti-interference performance of the equipment, overcomes the defects of measurement error, signal attenuation and poor environmental adaptability caused by insufficient assembly precision in the prior art, and makes the assembly process more suitable for mass production and more stable in performance.

[0029] Second, in the preferred implementation, the step 1 of the present application pre-processes the quartz substrate rectangular step surface by plasma cleaning or chemical cleaning, which can effectively remove surface impurities and oxide layer, improve the adhesion and uniformity of the solder film; the thickness of the solder film is 1-100 microns, which can ensure the thickness consistency and surface finish of the film, thereby improving the reliability and conductivity of the welding process.

[0030] Third, in the preferred implementation, the present application strictly controls the parallelism deviation (≤5 microns) and positioning accuracy deviation (≤100 microns) of the two VIA chips in step 2, which improves the assembly accuracy of the chips and ensures the symmetry consistency of the two chips in the differential detection process. Such high-precision assembly effectively reduces the signal deviation caused by installation errors, improves the sensitivity and measurement accuracy of the accelerometer, and enhances the anti-environmental interference ability. Both the chip and the base are made of quartz material, and the thermal expansion coefficient and other characteristics are consistent, which effectively avoids the stress and strain problem caused by temperature change.

[0031] Fourth, in the preferred implementation, the step 3 of the present application uses a precision temperature-controlled hot plate or an infrared heating system or a laser heater, which strictly controls the heating and cooling rate at ≤5℃ / min and maintains it for 5-10 minutes within the melting point range of the solder, which can effectively reduce the thermal stress and welding defects caused by rapid temperature change during the welding process, and improve the reliability and consistency of the welding interface.

[0032] Fifth, in the preferred implementation, the low outgassing rate vacuum adhesive of the present application can effectively reduce the gas release in the cavity, maintain the long-term stability of the vacuum environment, and the metal solder provides excellent thermal conductivity and mechanical strength, ensuring the reliability of the assembly in high and low temperature cycle and vibration environment.

[0033] Sixth, in the preferred implementation, the present application uses gold wire bonding or precision welding process to connect the circuit board and VIA chip to the conductive pin through metal electrodes, which ensures high stability and low loss of signal transmission, and has strong mechanical strength and long-term reliability; vacuum packaging uses any one of vacuum laser welding, eutectic welding or brazing process, which can be flexibly selected according to application requirements, ensuring high airtightness and mechanical strength of the shell, and effectively realizing electromagnetic shielding.

[0034] Seventh, the quartz base plane differential type quartz vibration beam accelerometer provided by the application effectively reduces the influence of air resistance on the vibration of the vibration beam, improves the vibration quality factor (Q value) of the vibration beam, and thus enhances the sensitivity and precision of acceleration measurement. At the same time, the high-precision positioning and stable connection of the VIA chip are realized through the rectangular step and the solder film on the quartz substrate, the environmental interference such as temperature drift and common-mode noise is suppressed by combining the differential detection technology, and the measurement precision and anti-interference ability are further improved. Compared with the problems of large temperature drift, weak anti-interference ability and difficult to guarantee the installation precision in the prior art, the chip structure layout and circuit design of the application are optimized, so that the system has higher measurement stability and reliability, and has excellent batch assembly characteristics.

[0035] Eighth, in the preferred implementation mode, the conductive pin embedded tube shell design of the application makes the signal transmission path more stable, and the ceramic sealing technology ensures that the conductive performance and the vacuum sealing performance are considered; the welding connection mode of the box and the tube shell not only improves the overall mechanical strength and air tightness of the shell, but also effectively realizes electromagnetic shielding, avoiding the influence of external electromagnetic interference on the performance of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is an assembly schematic diagram of the quartz vibration beam accelerometer of the embodiment of the application;

[0037] Figure 2 is a three-dimensional structural diagram of the quartz vibration beam accelerometer of the embodiment of the application without assembling the box;

[0038] Figure 3 is a three-dimensional structural diagram of the quartz vibration beam accelerometer of the embodiment of the application with assembling the box;

[0039] Figure 4 is a three-dimensional structural diagram of the quartz substrate of the embodiment of the application;

[0040] Figure 5 is a flowchart of the assembly method of the quartz vibration beam accelerometer of the embodiment of the application.

[0041] Among them, 1 is a box; 2 is a circuit board; 3 is a VIA chip; 4 is a quartz substrate; 4-1 is a quartz body; 4-2 is a rectangular step; 4-3 is a solder film; 5 is a tube shell; 6 is a conductive pin. DETAILED DESCRIPTION

[0042] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and embodiments.

[0043] In the description of the present application, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; the term "multiple" refers to two or more, unless otherwise explicitly limited. The terms "mounting", "connecting", "connecting", "fixing" and the like should be broadly understood, for example, "connecting" can be fixed connection, or detachable connection, or integrally connected; "connected" can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the description of the present application, it should be understood that the terms "up", "down", "left", "right", "front", "back" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or units referred to must have a particular direction, be constructed and operated in a particular orientation, therefore, cannot be understood as a limitation on the present application.

[0045] In the description of the present application, the terms "one embodiment / way", "some embodiments / ways", "specific embodiments / ways" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments / ways or examples are included in at least one embodiment / way or example of the present application. In the present description, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments / ways or examples in a suitable manner.

[0046] The quartz vibrating beam accelerometer is a high-precision sensor that can directly convert acceleration into frequency signal output by using the unique piezoelectric effect and elastic properties of quartz material. However, in the process of use, the inventors found that the quartz vibrating beam accelerometer would have large performance fluctuations, poor stability and low long-term reliability.

[0047] After a large number of experimental researches, the inventors found the root cause of the problem. The inventors found that the performance fluctuation was mainly caused by the fixing of the core chip assembly by the metal base and the gluing process. This fixing method would not cause a large problem for general chips, but would seriously affect the performance of the chip in the accelerometer. In extreme temperature and complex mechanical environment, the aging and performance inconsistency of the gluing material would easily lead to device failure. In addition, the inventors found that due to the mismatch of the thermal expansion coefficients of the metal base and the quartz chip, thermal stress would be generated in the high and low temperature cycle environment, which would cause chip performance fluctuation or even damage.

[0048] In view of the above technical bottleneck, based on a large number of experimental researches, the quartz base planar differential type quartz vibrating beam accelerometer is provided, the quartz base is adopted to replace the metal base, the high-precision rectangular step is designed, and the stable installation of the chip is realized through the solder film technology, which improves the reliability of the assembly and eliminates the defects caused by the adhesive process. By introducing the specially designed solder film and optimizing the welding conditions, the defects of the traditional process are fundamentally solved, the solder film is made of low-melting-point high-strength metal alloy material, the composition is accurately matched, and good heat conductivity and oxidation resistance are combined, the thickness of the solder film is controlled in the range of 1-100 mu m, and the magnetron sputtering or evaporation process is used to prepare the solder film to ensure the uniformity of the film thickness and the strength of the bonding force, the wetting enhancer and the antioxidant (such as titanium, chromium and palladium) are added in the film to improve the bonding capacity with the quartz substrate, and the oxidation and interface delamination in the high-temperature welding process are avoided. At the same time, in view of the high-temperature sensitivity of the solder film, a special welding process condition is adopted, and the potential damage of the high-temperature welding to the quartz chip and the substrate is successfully solved, and the thermal stress problem of the device is reduced. In the experiment, the material ratio, thickness uniformity and heat treatment process of the solder film are optimized, the mismatching problem of the thermal expansion coefficient between the chip and the base is successfully solved, and the performance stability of the device in extreme environment is greatly improved. At the same time, a simplified planar differential structure is designed, and the chip is arranged symmetrically to further improve the anti-interference ability and measurement precision. The optimized vacuum packaging process reduces the assembly complexity and manufacturing cost, and promotes the batch production of the device. The technical scheme not only effectively overcomes the shortcomings of the prior art, but also lays a solid foundation for the application of high-precision quartz vibrating beam accelerometer in complex environment.

[0049] As shown in the accompanying drawings Figures 1-4 The quartz base planar differential type quartz vibrating beam accelerometer is disclosed, which comprises a shell, and a circuit board 2, a VIA chip 3, a quartz substrate 4 and a conductive pin 6 arranged in the shell.

[0050] The shell is internally a vacuum cavity, which is designed to effectively optimize the performance of the quartz vibrating beam accelerometer. Specifically, it reduces air resistance, improves temperature stability, and reduces the impact of environmental pollutants. The vacuum environment eliminates the obstruction of air to the vibration of the vibrating beam in the VIA chip 3, reduces energy loss, and thus improves the vibration quality factor (Q value) of the vibrating beam. This allows the vibrating beam to maintain higher sensitivity when subjected to external disturbances, ensuring the accuracy of the acceleration measurement. The vibration frequency of the quartz vibrating beam is very sensitive to temperature changes. The presence of air can cause heat conduction effects, which in turn affect the temperature stability of the vibrating beam. The vacuum cavity isolates the effects of air, providing a more stable working environment for the vibrating beam, further improving the reliability of the measurement. The vacuum cavity effectively prevents moisture, dust and other pollutants from entering the shell, isolates the long-term effects of moisture and particulate matter on the vibrating beam, avoids potential damage to the performance of the VIA chip 3 and the quartz substrate 4, prolongs the life of internal components, and ensures the long-term stability of the device.

[0051] The quartz substrate 4 includes a quartz body 4-1, a rectangular step 4-2, and a solder film 4-3. The quartz body 4-1 is used to provide base support and structural stability. The rectangular steps 4-2 are spaced apart on the quartz body 4-1 and are used to precisely position and secure the VIA chips 3. The solder film 4-3 is plated on the rectangular steps 4-2 to provide an efficient soldering interface for the installation of the VIA chips 3. Two VIA chips 3 are installed between two spaced-apart rectangular steps 4-2 and are secured by the solder film 4-3, achieving a stable mechanical connection and reliable signal transmission. The two VIA chips 3 are designed to differentially detect acceleration and output positive and negative signals, respectively. Differential detection can effectively suppress environmental noise interference, further improving measurement accuracy and anti-interference ability. Each VIA chip 3 is provided with a circuit board 2 on one side. The drive circuit and amplification circuit on the circuit board 2 are connected to the metal electrodes of the corresponding VIA chip 3. The drive circuit on the circuit board 2 provides the drive signal required for the vibrating beam resonance of the VIA chip 3, ensuring stable operation of the vibrating beam, and receives the vibrating beam frequency signal from the VIA chip 3 and performs preliminary signal amplification and processing through the amplification circuit.

[0052] Each circuit board 2 is provided with a conductive pin 6 connected to it on the outside. The conductive pin 6 transmits the processed signal of the circuit board 2 to the external device, realizing the signal output of the accelerometer and the external system. The control signal of the external device is transmitted to the circuit board 2 through the conductive pin 6, thereby realizing accurate regulation and control of the vibrating beam working state of the VIA chip 3. The circuit board 2, as a signal transfer and processing station, connects the VIA chip 3 and the conductive pin 6, forming an efficient interaction path between the internal signal and the external system, ensuring real-time response and high-precision measurement capability of the device.

[0053] In the preferred implementation of the present application, the circuit board 2 uses miniaturized, temperature-insensitive components to reduce the impact of external environment on performance.

[0054] The VIA chip 3 is the core component of the quartz beam accelerometer, responsible for sensing external acceleration and converting it into an electrical signal. The VIA chip 3 includes a beam, a mass, a flexible hinge, a vibration isolation frame, a fixed frame, and metal electrodes. The beam is the key component for acceleration sensing. When the quartz beam accelerometer is subjected to external acceleration, the beam will undergo a small elastic deformation, causing a change in vibration frequency. This frequency change is proportional to the size of the acceleration, providing a basis for subsequent signal processing. The mass is used to provide inertial mass and is the direct source of force on the beam. Under the action of external acceleration, the mass will generate an inertial force, causing the beam to deform, forming a proportional relationship between acceleration and beam frequency, ensuring the physical accuracy of the sensing process. The flexible hinge connects the beam and the mass, providing structural support and flexible deformation capability. Its design allows the beam to vibrate freely under the action of inertial force while maintaining the mechanical stability of the system. The vibration isolation frame is used to isolate high-frequency vibrations and mechanical shocks from the external environment, avoiding external interference on the vibration of the beam and ensuring the purity of the signal. The fixed frame is used to provide mechanical support for the entire VIA chip, allowing it to be securely mounted on the quartz substrate while reducing possible displacement or deviation during beam vibration. The metal electrodes are used to convert the frequency change of the beam into a processable electrical signal output, providing input for subsequent signal amplification and processing by the circuit board 2.

[0055] To improve measurement accuracy, the quartz beam accelerometer uses a differential detection scheme. The quartz base plane differential quartz beam accelerometer uses two VIA chips 3 with consistent structure and performance, one for positive acceleration signal detection and the other for negative acceleration signal detection. The frequency signals output by the two VIA chips 3 are acceleration responses in the positive and negative directions, respectively. By differentiating the positive and negative signals, error sources such as temperature drift and common-mode noise can be effectively eliminated. Since the responses of the two chips to temperature changes are consistent, differential operation can reduce errors caused by temperature changes, and the suppression effect on external common-mode noise (such as mechanical vibration and electromagnetic interference) is significant. Differential detection can improve the sensitivity and accuracy of acceleration measurement, ensuring the stability and reliability of the system.

[0056] Specifically, when external acceleration acts on the accelerometer, the inertial mass (within the VIA chip) generates a corresponding force, causing the vibration beam to deform. The deformation of the vibration beam causes a change in its vibration frequency, which is detected by the metal electrode and an electrical signal is output. The oscillation circuit of the circuit board 2 provides a driving signal for the vibration beam to ensure its resonance. The frequency signal output by the vibration beam is amplified by the signal amplification circuit of the circuit board to enhance the signal strength and reduce noise. Two VIA chips 3 differentially detect acceleration, with one positive and one negative output signal. The differential output can eliminate environmental errors (such as frequency drift caused by temperature changes) and improve measurement accuracy. The processed acceleration signal is transmitted to external devices through the conductive pins 6 for subsequent analysis or display.

[0057] Further, differential detection uses two VIA chips with consistent structural performance to detect signal changes in the same acceleration environment, eliminates common-mode interference and errors through subtraction operation, and improves measurement accuracy. Two VIA chips (referred to as chip A and chip B) measure acceleration simultaneously, but in opposite directions (one detects positive acceleration and the other detects negative acceleration). The difference between the output signals can effectively eliminate environmental noise and system errors such as temperature drift and mechanical vibration. The differential formula is:

[0058] Δf = f A -f B

[0059] In the formula, Δf represents the net frequency signal after differential, which is directly proportional to the external acceleration; f A represents the frequency signal output by chip A; and f B represents the frequency signal output by chip B.

[0060] The two VIA chips 3 are installed on the quartz substrate 4 and are symmetrically placed. The vibration beam directions of the chips are opposite (for example, one is upward and the other is downward). Under the action of the same acceleration, the vibration beams of the two chips are subjected to forces in opposite directions, resulting in opposite signs of the output frequency changes. Each VIA chip 3 has an independent driving circuit, but shares the same environmental conditions (temperature, pressure, etc.).

[0061] External acceleration (such as gravitational acceleration or linear acceleration) acts on the entire system, and the inertial masses of the two VIA chips 3 respectively feel inertial forces of the same size but opposite directions. Acceleration causes the deformation of the vibration beam, resulting in an increase (or decrease) in the frequency of the vibration beam of chip A and a decrease (or increase) in the frequency of the vibration beam of chip B. Since the chips are symmetrically arranged, the frequency change amplitudes of the two chips are the same but the signs are opposite. The circuit board receives the frequency signals f A and f BThe net frequency change Δf is obtained by differential calculation. Differential calculation can automatically offset common-mode noise, such as temperature drift: temperature changes have the same effect on the frequencies of the two chips, which is offset after differential calculation. Mechanical vibration: random vibration in the non-acceleration direction has the same effect on the two chips, which is also offset after differential calculation. After the net frequency change Δf is processed by circuit (such as amplification, linearization), the corresponding acceleration value is output.

[0062] In the preferred implementation of the present application, the elastic coefficient of the tuning fork of the VIA chip 3, the weight of the mass block, the stiffness of the flexible hinge, and the conductivity of the metal electrode are strictly matched to ensure that the two VIA chips 3 have consistent performance. The vibration isolation frame and the fixed frame are made of high-strength and low-expansion materials to maximize the isolation of external interference and ensure the stability of the working environment of the tuning fork. The differential signals of the two VIA chips 3 are amplified and filtered by the amplification circuit of the circuit board 2 with high gain to further enhance the noise immunity.

[0063] The quartz body 4-1 is used to provide a stable mounting platform for the VIA chip 3. The quartz body 4-1 is processed by high-precision machining technology, and the surface has extremely low roughness (Ra value), which ensures that the chip can be smoothly attached and reduces the vibration and deviation that may occur during installation, thereby improving the working stability and measurement accuracy of the chip. The rectangular steps 4-2 on the quartz body 4-1 are evenly distributed and arranged at intervals to accurately position the mounting position of the VIA chip 3. The rectangular steps 4-2 provide support for the VIA chip 3 while positioning, and ensure that the VIA chip 3 is fixed and stable through the welding process, and is not easily affected by external forces or environmental factors to cause displacement or looseness. The solder film 4-3 is uniformly plated on the surface of the rectangular step by magnetron sputtering or evaporation process, which ensures that the film thickness is consistent and the bonding force is strong, meeting the high-precision installation requirements. The solder film 4-3 not only has excellent conductivity, but also has high thermal conductivity, which can quickly dissipate the heat generated by the VIA chip 3 during operation, avoiding the influence of local overheating on the performance of the VIA chip 3.

[0064] In the preferred implementation of the present application, the quartz body 4-1 is made of high-purity quartz material, which has excellent mechanical strength and thermal expansion coefficient matching performance, and can provide stable support in extreme environments. The length of each rectangular step 4-2 is 20-30 mm, the width is 0.5-2 mm, and the height is 0.2-1 mm. The machining precision of the rectangular step 4-2 is controlled within microns to ensure the accuracy of chip positioning. The uniformity of the solder film 4-3 is achieved by optimizing the process of magnetron sputtering or evaporation. The solder can be indium, indium-tin alloy, tin-silver alloy or tin-silver-copper alloy, etc. The thickness of the solder film 4-3 is 1-100 μm. At the same time, the bonding force between the solder film 4-3 and the rectangular step 4-2 is further improved by controlling the surface pretreatment (such as cleaning, plasma activation) of the rectangular step 4-2. In the VIA chip 3 welding process, precise positioning tooling and temperature control welding technology are used to ensure the integrity of the solder film 4-3 and the close contact of the VIA chip 3. After welding, thermal cycle test and mechanical vibration test are carried out to verify the installation reliability of the VIA chip 3.

[0065] The conductive pins 6 are used to transmit the output signals of the circuit board and the VIA chip to external devices. The conductive pins 6 are made of metal (such as gold-plated copper or beryllium copper) with excellent conductivity and oxidation resistance to ensure the stability and low loss of signal transmission. The conductive pins 6 are connected with the shell through a ceramic sealing process. The ceramic sealing material has excellent airtightness, which can effectively prevent gas leakage in the vacuum cavity and isolate the intrusion of external moisture or contaminants. The ceramic sealing material also has high resistivity, which ensures the insulation performance between the conductive pins 6 and the shell, avoiding leakage or interference in signal transmission.

[0066] To improve the structural stability, the sealing material and the pins are made of materials with matching thermal expansion coefficients (such as the composite structure of alumina ceramic and metal pins), which are firmly combined through the metallized ceramic surface, thereby avoiding sealing failure or mechanical loosening caused by temperature changes. In the preferred implementation of the present application, the ceramic sealing material is high-purity alumina, and the pin material surface is plated with gold or silver, which not only improves the conductivity but also enhances the corrosion resistance. The sealing process uses active brazing or glass ceramic sealing process to ensure the bonding strength and airtightness of the ceramic and metal pins. The sealing performance is tested by vacuum leakage rate to ensure the long-term stability of the vacuum cavity.

[0067] Further, the shell of the quartz base planar differential quartz beam accelerometer includes a can 1 and a tube 5. The can 1 is precisely machined from high-strength metal material (such as Kovar alloy, stainless steel or copper alloy), which has excellent mechanical strength, air tightness and electrical conductivity, and is suitable for vacuum sealing and electromagnetic shielding requirements. The tube 5 includes a metal base, and a conductive pin 6 is embedded in the metal base to provide a signal input and output path. The metal base and the can 1 are vacuum sealed and electromagnetically shielded by one of the following high-reliability welding techniques:

[0068] 1. Vacuum laser welding: The welding is completed in a vacuum environment using a high-energy density laser beam. It has the advantages of narrow weld, small heat-affected zone and high welding strength, effectively avoiding the influence of thermal deformation on the vacuum sealing performance.

[0069] 2. Eutectic welding: The combination of the metal base and the can is completed by forming a eutectic phase of the welding material at a specific temperature. It has the advantages of high bonding strength, high temperature resistance and low temperature resistance, and is suitable for long-term stable use.

[0070] 3. Brazing: The gap between the can 1 and the tube 5 is filled with solder, and the solder is melted by heating to achieve sealing. The process is relatively simple and suitable for medium-precision sealing requirements.

[0071] After welding, the surface of the can 1 and the tube 5 is treated to prevent oxidation (such as nickel plating or passivation) to enhance corrosion resistance and prolong equipment life. The welded tube 5 and can 1 can be subjected to vacuum leak testing, mechanical performance testing and electromagnetic shielding testing. Vacuum leak testing is performed using a helium mass spectrometer to ensure long-term vacuum stability of the welded seal. Mechanical performance testing is performed by vibration, impact and thermal cycle testing to verify the mechanical reliability of the welded joint. Electromagnetic shielding testing is performed by EMI (electromagnetic interference) testing to evaluate whether the shielding performance meets the design requirements.

[0072] Example 1

[0073] By comparing the structure of the existing technology cylindrical barrel type quartz beam accelerometer and the quartz base planar differential quartz beam accelerometer of the present application, the advantages of the quartz base planar differential quartz beam accelerometer of the present application are illustrated.

[0074] Table 1

[0075]

[0076]

[0077] As described in the specification Figure 5 , the present application also describes a packaging method of a quartz base planar differential quartz beam accelerometer, which comprises:

[0078] Step 1: Pre-treat the rectangular stepped surface of the quartz substrate and plate solder film on the rectangular stepped surface.

[0079] The purpose of Step 1 is to enhance the bonding force between the quartz substrate surface and the solder film, ensure that the film does not fall off or warp, and improve the reliability and stability of the assembly. Provide a uniform and high-quality solder film as the basis for subsequent welding or bonding, ensuring the thermal conductivity and mechanical strength of the welded area. Ensure the consistency of the film thickness, reduce process deviation, and improve the quality consistency and controllability of mass production.

[0080] Specifically, the solder film is made of low-melting-point high-strength metal alloy, and through careful design of the formula combination, the welding performance, mechanical strength and oxidation resistance are considered. The composition of the solder film includes metal alloy matrix, wetting enhancer, antioxidant and conductive enhancer.

[0081] The metal alloy base is the main component of the solder film, which is used to provide the base material for the melting soldering, and determines the soldering temperature range and the mechanical properties after soldering. The metal alloy base includes one of gold-tin alloy (Au80Sn20), indium-tin alloy (In50Sn50), bismuth-tin alloy (Bi58Sn42), silver-tin alloy (Ag3Sn), and indium-bismuth-tin alloy (In52Bi32Sn16), but is not limited thereto. The gold-tin alloy (Au80Sn20) is composed of 80% gold (Au) and 20% tin (Sn), has excellent low melting point performance (melting point about 280℃) and high mechanical strength, and shows excellent electrical conductivity and corrosion resistance after soldering. The indium-tin alloy (In50Sn50) is composed of 50% indium (In) and 50% tin (Sn), has a lower melting point (about 200℃), is suitable for more stringent temperature control scenarios, and has good flexibility and stability in a thermal cycle environment. The bismuth-tin alloy (Bi58Sn42) is composed of 58% bismuth (Bi) and 42% tin (Sn), has a low melting point (about 138℃), is suitable for very low temperature soldering, avoids overheating of the chip, and the addition of bismuth (Bi) increases the mechanical strength and fatigue resistance of the soldering point. The silver-tin alloy (Ag3Sn) is composed of 3% silver (Ag) and 97% tin (Sn), can provide high electrical conductivity and good wettability, has strong high temperature resistance, and meets the high electrical conductivity requirement of precision assembly. The indium-bismuth-tin alloy (In52Bi32Sn16) is composed of 52% indium (In), 32% bismuth (Bi), and 16% tin (Sn), has a low melting point (about 90℃), shows good flexibility and reliability at ultra-low temperature, and the enhancement of bismuth (Bi) improves the vibration resistance of the soldering point, meeting the application requirements of low temperature environment and high vibration. The metal alloy base reduces the soldering temperature (90℃-300℃), and reduces the damage of high temperature to the quartz substrate and the chip. Among them, the tin in the base metal composition can enhance the heat diffusion capacity of the soldering point, prevent local overheating or rapid cooling caused by stress.

[0082] The wetting enhancer includes one of titanium (Ti), chromium (Cr), zirconium (Zr), nickel (Ni), molybdenum (Mo), but is not limited thereto. Titanium (Ti) as a wetting enhancer, the content is controlled at 1% to 2%, can improve the wettability of the solder film and the surface of the quartz substrate, promote the chemical combination of the metal and non-metal interface. Chromium (Cr) has a similar effect as titanium, the content is controlled at 0.5% to 1%, improves the bonding strength of the solder film, reduces the possibility of interface peeling. The doping amount of zirconium (Zr) is 0.1% to 0.5%, which can improve the interface wettability of the metal film and the substrate, and also has good chemical stability in high temperature welding. The doping amount of nickel (Ni) is 0.5% to 1%, which can enhance the wetting performance of the film, improve the fatigue resistance of the welding point, and also provide good corrosion resistance. The doping amount of molybdenum (Mo) is 0.1% to 0.3%, which can improve the wetting performance and reduce the interfacial tension during welding, and also plays an important role in improving the interfacial bonding strength.

[0083] The antioxidant includes one of palladium (Pd), iridium (Ir), platinum (Pt), rhenium (Re), manganese (Mn), but is not limited thereto. The doping amount of palladium (Pd) is 0.1% to 0.5%, which can effectively inhibit the oxidation of the solder surface due to its stable chemical properties, and prolong the service life of the welding point. The doping amount of iridium (Ir) is 0.05% to 0.2%, which can enhance the oxidation resistance while improving the high temperature resistance and mechanical strength of the solder film. The doping amount of platinum (Pt) is 0.1% to 0.5%, which has high oxidation resistance and can effectively inhibit the oxidation reaction on the surface of the solder in high temperature environment, thereby prolonging the service life of the welding point. The doping amount of rhenium (Re) is 0.05% to 0.1%, which can provide high temperature oxidation resistance and enhance the durability and stability of the solder film. The doping amount of manganese (Mn) is 0.1% to 0.3%, which can improve the oxidation resistance and form a protective film on the welding area, thereby reducing the corrosion and aging of the welding point.

[0084] The conductive enhancer includes one of silver (Ag), copper (Cu), tungsten (W), zinc (Zn), but is not limited thereto. The doping amount of silver (Ag) is 1% to 3%, which can improve the electrical conductivity and thermal conductivity of the solder film, and also form a fine grain structure in the welding area to enhance the mechanical strength. The doping amount of copper (Cu) is 1% to 3%, which can provide good electrical conductivity and thermal conductivity, and also improve the mechanical strength of the welding area. The doping amount of tungsten (W) is 0.5% to 1%, which can maintain good electrical conductivity in high temperature environment, provide high thermal conductivity, and reduce the thermal resistance of the welding area. The doping amount of zinc (Zn) is 0.1% to 0.3%, which can improve the electrical conductivity of the film, and also optimize the coefficient of thermal expansion matching of the welding point to provide more stable signal transmission capability.

[0085] Preparation of the solder film:

[0086] S1: Surface treatment before coating: The rectangular step surface of the quartz substrate is activated by plasma cleaning or chemical cleaning (such as dilute hydrofluoric acid solution) to remove the oxide layer and particulate impurities, and to enhance the adhesion of the solder film.

[0087] S2: Sputtering or evaporation technology: The working gas pressure is controlled at 0.5-1.0 Pa, the sputtering power is controlled at 150W-300W, and the sputtering rate is adjusted to 0.1 μm / min to ensure the uniformity of thin film deposition. For the evaporation process, the heating temperature is strictly controlled below the melting point of the solder alloy, and the vacuum degree is maintained at 10 -5 Torr.

[0088] S3: Thickness uniformity control: The thin film thickness is accurately monitored by a quartz crystal microbalance to ensure that the solder film thickness is uniformly distributed within the range of 1 μm-100 μm, and the thickness deviation is ≤5%.

[0089] Step 2: The two VIA chips are initially placed on the rectangular step of the quartz substrate, and the position of the VIA chips is precisely adjusted using a micro-mechanical adjustment tool.

[0090] The purpose of step 2 is to achieve precise alignment of the chips on the rectangular step of the quartz substrate, ensuring that the chip spacing, parallelism and positioning accuracy meet the design requirements. It provides a reliable structural foundation for high-precision detection of differential quartz beam accelerometers, reducing performance deviations caused by assembly errors. Precise tools and detection equipment are used to optimize the chip position adjustment process, reducing the error rate of manual adjustment and adapting to large-scale automated assembly.

[0091] Specifically, the two VIA chips are pre-aligned at the specified position of the rectangular step using a high-precision manipulator, and then a preliminary position detection is performed using an optical microscope. After precise position adjustment using a micro-mechanical adjustment tool, a laser interferometer is used to assist in detecting the parallelism and position deviation of the two VIA chips. The parallelism deviation is controlled to be ≤5 μm, and the positioning accuracy deviation is controlled to be ≤100 μm. Through the design of planar structure and high-precision adjustment, the high precision and stability of differential detection are ensured.

[0092] Step 3: The assembly of the quartz substrate and the VIA chips is heated to the melting point temperature of the solder at a set heating rate, and then slowly cooled at a set cooling rate after a certain period of time to realize the welding of the quartz substrate and the VIA chips.

[0093] The purpose of Step 3 is to achieve a firm connection between the quartz substrate and the VIA chip, forming a stable electrical and mechanical junction, ensuring reliability over long-term use. Precise temperature control is used to avoid material thermal stress caused by thermal shock or uneven heating, reducing deformation and internal defects of the assembly after soldering. An alternative bonding process is provided, reducing reliance on solder and improving assembly adaptability by using UV or optical glue for different application scenarios.

[0094] Specifically, the heating equipment uses precise temperature control hot plates or infrared heating systems or laser heaters for uniform heating. During the soldering process in Step 3, in order to solve the high-temperature soldering problems that may be caused by the thin thickness of the solder film (only 1-100 μm) (such as uneven melting of the film, chip damage or insufficient soldering strength), the following special soldering processes and conditions must be used:

[0095] 1. Precise temperature control rate: Due to the thin thickness of the solder film, the heating rate needs to be strictly controlled at ≤5 ℃ / min to ensure uniform heating and avoid damage to the chip structure caused by thermal shock. The cooling rate is also kept at ≤5 ℃ / min to prevent material deformation or cracking caused by accumulated thermal stress.

[0096] 2. Local heating technology: Laser heating or infrared local heating technology is used, and the heating equipment uses precise temperature control hot plates or infrared heating systems or laser heaters. Through focused high energy density heating, only the soldering area is heated to avoid thermal damage to other areas of the quartz substrate and chip.

[0097] 3. High vacuum environment soldering: During the soldering process, the environmental vacuum degree needs to reach 10 -6 Torr to reduce oxidation and contamination, ensuring the cleanliness and bonding strength of the soldering interface.

[0098] 4. High precision real-time monitoring: Optical interferometer or infrared thermal imager is used to monitor the temperature distribution of the soldering area and the state of the soldering film in real time, ensuring uniform melting of the solder and good bonding with the quartz substrate and chip.

[0099] Alternatively, the quartz substrate and VIA chip can also use a bonding process using low-stress UV glue or deep optical glue applied to the surface of the quartz material through UV curing technology. Since both the quartz substrate and the VIA chip are quartz materials, the internal stress is reduced through homogenous bonding, suitable for high and low temperature environments, and solder can be optional or unnecessary. After bonding, the bonding quality is verified through mechanical vibration and thermal cycle tests.

[0100] Step 4: Install the assembly formed by the soldered quartz substrate and VIA chip into the middle area of the tube shell.

[0101] The purpose of Step 4 is to ensure that the combined components are stably fixed in the tube shell, providing a solid and precise positional reference for subsequent assembly steps. It improves the anti-vibration performance and impact resistance of the entire device, adapting to complex working environments. By choosing vacuum glue or metal solder, long-term vacuum performance of the components is ensured, meeting strict requirements for environmental airtightness.

[0102] Specifically, the combined quartz substrate 4 and VIA chip 3 components are installed in the middle region of the tube shell 5 using low outgassing rate vacuum glue or metal solder, ensuring the stability and long-term vacuum performance of the components. Process parameters include glue curing temperature: 50-100°C, time control for 1-2 hours. Welding process: low-temperature eutectic welding, solder melting point 150-200°C. After welding, a three-coordinate measuring instrument is used to calibrate the installation position, ensuring the flatness and stability of the components and the tube shell 5.

[0103] Step 5: Bond the circuit board to both ends of the quartz substrate.

[0104] The purpose of Step 5 is to achieve the fixation of the circuit board and the quartz substrate through reliable bonding methods, preventing the device from failing under vibration and impact conditions. Ensure the uniformity of the glue layer during the bonding process to avoid signal transmission instability caused by bonding defects. Provide high-strength bonding while verifying the bonding quality through detection to ensure the long-term stability of the bonding site.

[0105] Specifically, the circuit board is bonded to both ends of the quartz substrate using low outgassing rate vacuum glue or metal solder, ensuring uniform coverage of the glue layer at the bonding site and avoiding voids. The glue layer thickness is controlled at 0.1-0.5mm. After bonding, preliminary curing is performed, and then bonding strength is detected through tensile and shear experiments. A thermal infrared detection system is used to scan the bonding site to ensure there are no thermal defects.

[0106] Step 6: Install conductive pins on the tube shell, and electrically connect the circuit board and VIA chip to the conductive pins through metal electrodes.

[0107] The purpose of Step 6 is to establish reliable electrical connections between the circuit board and the VIA chip, ensuring efficient signal transmission. Provide effective electromagnetic shielding measures to avoid signal crosstalk caused by external interference, improving the signal integrity of the device. Ensure the mechanical strength and long-term electrical conductivity of the solder joints to meet the stable working requirements in complex electromagnetic environments.

[0108] Specifically, the circuit board and VIA chip are connected to the conductive pins through metal electrodes using a gold wire bonding or precision welding process. The wire material is selected to be gold or silver wire with a diameter of 20-50 μm to ensure conductivity and mechanical strength. The welding equipment uses an ultrasonic gold wire bonder combined with a temperature control system, and the welding temperature is controlled at 150-200°C. During the welding process, a local shielding structure is added to avoid signal crosstalk caused by external electromagnetic interference. The wire is covered with a shielding net or conductive coating to improve electromagnetic compatibility.

[0109] Step 7: Install the box cover above the tube shell and perform vacuum packaging. After welding, perform vacuum leak testing, mechanical performance testing, and electromagnetic shielding testing in sequence.

[0110] The purpose of step 7 is to perform airtight packaging of the device to protect internal components from external environments such as moisture and dust, extending the service life. Enhance the mechanical strength and structural integrity of the device to meet the vibration and impact requirements in complex working conditions. Ensure electromagnetic shielding performance to avoid the influence of external electromagnetic interference on device performance, and verify the sealing and performance stability of the device through multiple tests.

[0111] Specifically, vacuum packaging can use any one of vacuum laser welding, eutectic welding, and brazing welding processes (selected according to requirements), and the welding environment maintains a vacuum degree of 10 -6 Torr. The laser power and welding speed of the welding process are adjusted according to the material thickness to avoid overheating damage to the components, for example, the eutectic welding temperature is set at 180-220°C.

[0112] Through the above assembly method, the assembly precision and reliability of the quartz base planar differential quartz vibration beam accelerometer are improved, and the consistency and batch efficiency of the production process are optimized, providing strong support for the production of high-performance accelerometers.

[0113] Example 2

[0114] By comparing the assembly method of the cylindrical barrel type quartz vibration beam accelerometer of the prior art and the quartz base planar differential quartz vibration beam accelerometer of the present application, the advantages of the assembly method of the quartz base planar differential quartz vibration beam accelerometer of the present application are illustrated.

[0115] Table 2

[0116]

[0117]

[0118] As can be seen from Table 2, the application significantly improves the assembly precision and consistency, especially in welding, bonding and positioning adjustment, ensures the high-quality output of mass production, eliminates the influence of temperature drift and common-mode noise through differential detection and vacuum packaging technology, improves the detection precision and anti-interference ability, optimizes the solder film and bonding process, and the vacuum packaging technology ensures the long-term stability and environmental adaptability of the assembly.

[0119] The quartz base planar differential quartz vibration beam accelerometer provided by the application effectively reduces the influence of air resistance on the vibration of the vibration beam, improves the vibration quality factor (Q value) of the vibration beam, and thus enhances the sensitivity and precision of acceleration measurement. The rectangular step on the quartz substrate and the solder film realize high-precision positioning and stable connection of the VIA chip, effectively suppress environmental interference such as temperature drift and common-mode noise by combining differential detection technology, and greatly improve the measurement precision and anti-interference ability. The assembly method pre-treats the surface of the rectangular step and plates a solder film, uses a welding process with a set temperature rising rate, reduces internal stress and welding defects, and ensures the mechanical stability and long-term reliability of the assembly. During the assembly process, the micro-mechanical adjustment tool and the precise electrical connection process ensure the stability and low loss of signal transmission between the VIA chip, the circuit board and the conductive pin. The vacuum packaging process of the box and the tube shell is combined with a strict test process, which optimizes the vacuum sealing property and anti-interference performance, overcomes the problems of large temperature drift, weak anti-interference ability and insufficient assembly precision in the prior art, and makes the device have higher measurement stability, reliability and mass production adaptability.

[0120] The above-mentioned is only an embodiment of the application, and the common knowledge of specific structures and characteristics in the scheme is not described in detail. It is obvious for those skilled in the art that the application is not limited to the details of the above-mentioned exemplary embodiments, and the application can be realized in other specific forms without departing from the spirit or essential characteristics of the application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application. Any reference signs in the claims should not be regarded as limiting the claims.

Claims

1. A packaging method for a quartz base planar differential quartz vibrating beam accelerometer, characterized in that, The quartz base planar differential quartz vibrating beam accelerometer includes a sealed box (1) and a tube shell (5) fastened together, and a circuit board (2), a VIA chip (3), a quartz substrate (4), and conductive pins (6) disposed inside the sealed box (1) and the tube shell (5); the quartz substrate (4) includes a quartz body (4-1), rectangular steps (4-2), and a solder film (4-3), wherein the rectangular steps (4-2) are spaced apart on the quartz body (4-1) for positioning and fixing the VIA chip (3); the solder film (4-3) is plated on the rectangular steps (4-2) for soldering the VIA chip (3); the packaging method includes: Step 1: Pre-treat the rectangular step surface of the quartz substrate and deposit a solder film on the rectangular step surface; In step 1, the solder film comprises a metal alloy matrix, a wetting enhancer, an antioxidant, and a conductivity enhancer; the metal alloy matrix is ​​one of gold-tin alloy, indium-tin alloy, bismuth-tin alloy, silver-tin alloy, or indium-bismuth-tin alloy; the wetting enhancer is one of titanium, chromium, zirconium, nickel, or molybdenum; the antioxidant is one of palladium, iridium, platinum, rhenium, or manganese; and the conductivity enhancer is one of silver, copper, tungsten, or zinc. Step 2: Place the two VIA chips on the rectangular steps of the quartz substrate and use a micromechanical adjustment tool to precisely adjust the position of the VIA chips; Step 3: Heat the assembly formed by the quartz substrate and the VIA chip to the melting point of the solder at a set heating rate, hold for a certain time, and then slowly cool down at a set cooling rate to achieve the welding of the quartz substrate and the VIA chip. Step 4: Install the assembly formed by the welded quartz substrate and VIA chip into the middle area of ​​the tube shell. Step 5: Attach the circuit board to both ends of the quartz substrate; Step 6: Install the conductive pins onto the housing, and connect the circuit board to the VIA chip via metal electrodes and the conductive pins. Step 7: Place the sealing box on top of the tube shell and perform vacuum sealing. After welding, perform vacuum leakage test, mechanical performance test and electromagnetic shielding test in sequence.

2. The packaging method according to claim 1, characterized in that, Step 1, the process of depositing the solder film includes: The rectangular step surface of the quartz substrate is activated by plasma cleaning or chemical cleaning to remove the oxide layer and particulate impurities on the surface. Solder films can be prepared using magnetron sputtering or vapor deposition: For magnetron sputtering, the working gas pressure should be controlled at 0.5 ~ 1.0 Pa, the sputtering power at 150 W ~ 300 W, and the sputtering rate at 0.1 μm / min; or for vapor deposition, the heating temperature should be controlled below the melting point of the solder alloy while maintaining a vacuum level of [missing information]. ; During magnetron sputtering or evaporation, the film thickness is monitored in real time using a quartz crystal microbalance or quartz crystal film thickness measuring instrument. The film thickness is accurately monitored and controlled within the range of 1μm-100μm, with a thickness deviation of ≤5%.

3. The packaging method according to claim 1, characterized in that, In step 2, the parallelism deviation of the two VIA chips is ≤ 5μm, and the positioning accuracy deviation is ≤ 100μm.

4. The packaging method for the quartz base planar differential quartz vibrating beam accelerometer according to claim 1, characterized in that, In step 3, the welding process between the VIA chip and the quartz substrate includes: welding under a vacuum of... Under the specified conditions, a precision temperature-controlled hot plate, an infrared heating system, or a laser heater is used to uniformly heat the solder film on the rectangular step surface of the quartz substrate to the melting point temperature range of the solder at a heating rate of ≤5℃ / min. The solder film is then kept within the melting point temperature range for 5-10 minutes to ensure that the solder completely melts and fully bonds with the VIA chip and the quartz substrate to form a stable welding interface. After welding, the welding area is slowly cooled at a cooling rate of ≤5℃ / min.

5. The packaging method for the quartz base planar differential quartz vibrating beam accelerometer according to claim 1, characterized in that, In step 4, a low-outgassing-rate vacuum adhesive or metal solder is used to install the assembled quartz substrate and VIA chip assembly into the middle area of ​​the housing; in step 5, a low-outgassing-rate vacuum adhesive or metal solder is used to bond the circuit board to both ends of the quartz substrate.

6. The packaging method for the quartz base planar differential quartz vibrating beam accelerometer according to claim 1, characterized in that, In step 6, gold wire bonding or precision soldering is used to connect the circuit board and the VIA chip to conductive pins via metal electrodes.

7. The packaging method for the quartz base planar differential quartz vibrating beam accelerometer according to claim 1, characterized in that, In step 7, vacuum packaging employs any one of the following welding processes: vacuum laser welding, eutectic welding, and brazing.

8. A quartz base planar differential type quartz vibrating beam accelerometer, characterized in that, The quartz base planar differential quartz vibrating beam accelerometer is manufactured by the packaging method described in any one of claims 1-7.

9. The quartz base planar differential quartz vibrating beam accelerometer according to claim 8, characterized in that, The inside of the sealed box (1) and the tube shell (5) that are fastened together is a vacuum cavity; the two VIA chips (3) are mounted on the quartz substrate (4) and output positive and negative signals respectively through differential detection; each VIA chip (3) has a circuit board (2) on one side, the circuit board (2) includes a driving circuit and an amplification circuit, the driving circuit and the amplification circuit are connected to the metal electrode of the corresponding VIA chip (3); the circuit board (2) is used to provide driving signals for the VIA chip (3), and to receive and amplify the output signals of the VIA chip (3); each circuit board (2) has a conductive pin (6) on its outer side, the conductive pin (6) is embedded in the tube shell (5), the conductive pin (6) is used to transmit the signal processed by the circuit board (2) to an external device, and to receive control signals from the external device to regulate the working state of the VIA chip (3).

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