CN114354034A - Pressure sensor and manufacturing method thereof - Google Patents

Abstract

A pressure sensor and method of manufacture, the pressure sensor comprising: the shell is in a cylinder shape with one end opened and the other end closed; the conductive pins are inserted into the other end of the shell in parallel with the axial direction of the shell; the sensitive element is arranged in the shell and comprises a first cylinder and a second cylinder which are sequentially communicated, one end of the first cylinder, which is far away from the second cylinder, is closed, and the surface of one end of the first cylinder is provided with a plurality of resistors and a plurality of bonding pads which are electrically connected with the resistors; a lead element located within the housing and connected to the first cylinder of the sensing element; and the conductive curved pin is inserted in the lead element, one end of the conductive curved pin is electrically connected to the conductive pin, and the other end of the conductive curved pin is electrically connected to the bonding pad. The pressure sensor utilizes the lead element to replace a circuit board to communicate the bonding pad of the sensitive element with an external cable, greatly improves the high temperature resistance of the sensor, meets the requirement of measuring the environmental pressure of a high-temperature or wide-temperature area, and is suitable for various occasions of high-pressure measurement in a high-temperature environment.

Description

Pressure sensor and manufacturing method thereof

Technical Field

The invention belongs to the technical field of sensors, and particularly relates to a pressure sensor and a manufacturing method thereof.

Background

The pressure sensor is a basic mechanical sensor widely applied in the fields of industrial production, military equipment, aerospace, navigation and the like. The measurement principle mostly utilizes a Wheatstone bridge principle, a resistance strain effect or a piezoresistive effect, strain generated by the surface of an elastic body where bridge arm resistors are located under the action of pressure (pressure intensity) is converted into resistance value change of a resistance strain gauge, and then the resistance change is converted into a voltage signal through a Wheatstone bridge.

In some industrial fields, such as petroleum, chemical and metallurgical industries or fields, there is often a need for measuring medium and high pressure in a high temperature environment (above 200 ℃) for a long time, and in the fields of explosion tests and engine tests in aerospace and military fields, there are often high temperature and medium and high pressure test requirements, which have high requirements for frequency response (usually reaching above several kilohertz). When the silicon pressure-combined type force transducer based on the MEMS process is applied to the high-temperature field, a plurality of limitations, such as temperature compensation, are met, and when the silicon pressure-combined type force transducer is applied to the high-temperature environment, a relatively expensive compensation chip is needed, when the silicon pressure-combined type force transducer is applied to the medium-pressure field (dozens of atmospheric pressures to dozens of atmospheric pressures), silicon oil is generally needed to be filled to adapt to different medium characteristics, and the frequency response is greatly reduced; the silicon piezoresistive pressure sensor with high temperature resistance (above 200 ℃) has high requirements on raw materials and manufacturing equipment, generally cannot measure medium-high pressure, has poor temperature impact performance, cannot bear high temperature if packaged by silicone oil filling, has frequency response which is difficult to meet the requirements, and is expensive. The substrate of the strain gauge and the surface mount adhesive are organic matters, so that the aging is accelerated in a high-temperature environment, the service life is greatly reduced, the service life of the strain gauge in a typical metal smelting and petroleum industry hardly reaches half a year or more, the performance is obviously reduced in the high-temperature environment, the temperature characteristic consistency of the resistance strain gauge is hardly controlled, and the effective temperature compensation range is narrow by adopting temperature compensation on one hand, and the temperature influence is great on the other hand; for the requirement of medium-high pressure measurement in a high-temperature environment (above 200 ℃), the service life of a patch type pressure sensor is often not long enough, the problems of shutdown, test stop and the like are often caused when the sensor is replaced, larger loss and even technical bottleneck are caused, the patch type pressure sensor can be only used for one-time test under more conditions, the temperature compensation range is limited, the temperature impact performance is poor, and the requirements of high precision and repeated use are difficult to meet.

In addition, due to the rapid development of technologies such as computer technology, information technology, artificial intelligence and the like, military equipment and related fields of some core industries have higher requirements on distributed pressure measurement, sensors required in the occasions need to have the requirements of small volume and convenient installation besides the strict requirements on high temperature resistance and corrosivity, and also have the requirements on a test state (the shape of a pressure sensing surface of a test piece), the pressure sensing cross section is often required to be as small as possible, the influence on the pressure sensing surface of the test piece is reduced as much as possible, although silicon piezoresistive sensors have natural advantages in the aspects of miniaturization and mass production, the volume is difficult to control once a silicon oil filling technology is adopted during medium-high pressure measurement, patch type pressure sensors can be very small, but need high-level skilled personnel to manually assemble, the mass production is difficult, and the resistance value of the used strain gauges is difficult to be larger because of being too small, the sensor has large self-heating and poor thermal stability, and the preheating time and the measurement precision can influence the actual use effect; more complicated, the fields of industry, aerospace, military industry and the like which are continuously emerging are increasingly high in comprehensive requirements on the pressure sensor, sometimes, the special requirements of the different fields are overlapped, the requirements on the pressure sensor are multiplied, the pressure sensor belongs to a product with a large using amount, and if the mass production cannot be realized, the technical development is difficult to be effectively promoted, and good social benefits are generated.

Therefore, there is a need for a pressure sensor that is resistant to high temperatures, small in size, has a high frequency response, can cover at least the medium pressure range, has excellent lifetime and reliability, and is easy to mass produce.

Disclosure of Invention

The invention aims to provide a pressure sensor and a manufacturing method thereof, and aims to solve the problems that the traditional pressure sensor is difficult to meet the requirement of medium-high pressure measurement in a high-temperature environment (above 200 ℃) and is difficult to realize small measurement.

In order to achieve the above object, the present invention provides a pressure sensor comprising:

the shell is in a cylinder shape with one end open and the other end closed;

the conductive pins are inserted into the other end of the shell in parallel to the axial direction of the shell;

the sensitive element is arranged in the shell and comprises a first cylinder and a second cylinder which are sequentially communicated, one end of the first cylinder, which is far away from the second cylinder, is closed, and the surface of one end of the first cylinder is provided with a plurality of resistors and a plurality of bonding pads which are electrically connected with the resistors;

a lead element located within the housing and connected to the first cylinder of the sensing element;

the conductive curved pin is inserted in the lead element, one end of the conductive curved pin is electrically connected to the conductive pin, and the other end of the conductive curved pin is electrically connected to the pad.

Preferably, the sensing element and the shell are both made of martensitic stainless steel or high-temperature alloy, the shell comprises a first cylinder section, a second cylinder section and a third cylinder section which are sequentially communicated, the first cylinder section is in a hexagonal cylinder shape, one end of the first cylinder section is closed and provided with a plurality of needle holes, and each conductive needle penetrates through one needle hole; the outer wall of the second cylinder section is provided with external threads, and the outer diameter of the third cylinder section is smaller than that of the second cylinder section;

the second cylinder is inserted into the third cylinder section.

Preferably, the first cylinder is provided with a notch on the periphery thereof, the notch is parallel to the central axis of the first cylinder, the lead element is made of ceramic, austenitic stainless steel or high-temperature alloy, and comprises a connecting plate and a complementary circular plate extending from the connecting plate, the complementary circular plate is arranged at the notch and is used for complementing the notch.

Preferably, the sensor further comprises a hoop, wherein the hoop is sleeved on the peripheries of the first cylinder and the complementary circular plate and is in contact with the periphery of the first cylinder of the sensing element;

the first cylinder has an outer diameter less than an outer diameter of the second cylinder, and the hoop has an outer diameter the same as the outer diameter of the second cylinder.

Preferably, two resistor pairs are arranged on the end surface of the first cylinder of the sensing element, each resistor pair comprises a pair of resistors connected in series, and the resistor pairs are mutually and electrically connected to form a Wheatstone bridge;

the pad is electrically connected with the leading-out end of the resistor, and the pad is far away from the notch.

Preferably, at least one compensation resistor is further disposed on the end surface of the first cylinder of the sensing element, and the compensation resistor is electrically connected to the wheatstone bridge for bridge zero point compensation;

the resistor and the compensation resistor are both thin film resistors.

Preferably, the surface of the pad of the sensitive element, the surface of the conductive pin and the surface of the conductive bent pin are plated with gold layers.

Preferably, one end of the conductive curved pin, which is located in the housing, is provided with an insertion hole, the conductive curved pin comprises a vertical part and a horizontal part bent from the top end of the vertical part, the horizontal part of each conductive curved pin is electrically connected to one of the pads through a gold wire, and the other end of the vertical part of each conductive curved pin is inserted into one of the insertion holes.

Preferably, the sealing piece is connected with the other end of the shell in a sealing mode, the other end of the shell is provided with an air exhaust hole, the air exhaust hole is a stepped hole, and the sealing piece is connected with the inside of the stepped hole in a sealing mode and does not protrude out of the surface of the other end of the shell.

The invention also provides a manufacturing method of the pressure sensor, which comprises the following steps:

step 1: manufacturing the first cylinder and the second cylinder of the sensitive element, and forming the resistor, the bonding pad and an embedded connecting wire for electrically connecting the resistor and the bonding pad on the surface of one end of the first cylinder by using a sputtering film process;

step 2: manufacturing the lead element, the shell, the conductive curved pin and the conductive pin, and sintering the conductive curved pin on the lead element and the conductive pin on the other end of the shell by adopting a glass powder sintering process;

and step 3: connecting the lead element to a first cylinder of the sensitive element, and electrically connecting the bonding pad of the sensitive element and the conductive bent pin by using gold wire ball bonding;

and 4, step 4: inserting the conductive curved pin into the conductive pin to form contact conduction, sleeving the shell on the sensitive element, and welding, fixing and sealing the sensitive element and the shell by welding;

and 5: and placing the pressure sensor in a vacuum environment for a preset time, pumping out gas between the shell and the sensitive element, sealing the shell, and taking out the pressure sensor from the vacuum environment.

The invention relates to a pressure sensor, which has the beneficial effects that: the lead element is used for replacing a circuit board to communicate the bonding pad of the sensitive element with an external cable, so that the high temperature resistance of the sensor is greatly improved; the invention effectively solves the contradiction between multiple harsh requirements such as high precision, medium and high pressure, small volume, high frequency response, long service life, high reliability and the like under the environmental pressure measurement requirements of various high-temperature or wide-temperature areas, and is suitable for various occasions of high-pressure measurement in high-temperature environments in the fields of industry, aerospace and military industry.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.

FIG. 1 illustrates a first perspective structural view of a pressure sensor in accordance with an exemplary embodiment of the present invention;

FIG. 2 illustrates a second perspective structural view of a pressure sensor in accordance with an exemplary embodiment of the present invention;

FIG. 3 illustrates a schematic structural view of a housing in a pressure sensor in accordance with an exemplary embodiment of the present invention;

FIG. 4 illustrates a first perspective connection diagram of a sensing element, a lead element, and a hoop in a pressure sensor in accordance with an exemplary embodiment of the present invention;

FIG. 5 illustrates a second perspective connection diagram of the sense element, lead elements and hoop in the pressure sensor of an exemplary embodiment of the present invention;

FIG. 6 is a schematic diagram illustrating the angular connections of the sensing elements and lead elements in a pressure sensor in accordance with an exemplary embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating the structure of a sensing element in a pressure sensor in accordance with an exemplary embodiment of the present invention;

FIG. 8 shows a schematic diagram of the resistive arrangement of the sensing elements in the pressure sensor of an exemplary embodiment of the present invention;

FIG. 9 illustrates a schematic diagram of a Wheatstone bridge in a pressure sensor according to an exemplary embodiment of the invention.

Description of reference numerals:

1. a sensing element; 101. a first cylinder; 102. a second cylinder; 2. a housing; 201. a first barrel section; 202. a second barrel section; 203. a third barrel section; 3. a lead element; 301. a connecting plate; 302. supplementing a circular plate; 4. a hoop; 5. conducting bent pins; 6. a conductive pin; 7. gold thread; 8. a pad; 9. cutting the dough; 10. an external thread; 11. sealing plate, 12, resistance; 13. compensation resistor, 14, pinhole; 15. inserting holes; 16. air extraction holes 17 and a clamping table.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

In order to solve the problems in the prior art, the present invention provides a pressure sensor, as shown in fig. 1 and 9, including:

the shell 2 is in a cylinder shape with one end opened and the other end closed;

a plurality of conductive pins 6, the plurality of conductive pins 6 being inserted in the other end of the housing 2 in parallel with the axial direction of the housing 2;

the sensing element 1 is arranged in the shell 2 and comprises a first cylinder 101 and a second cylinder 102 which are communicated in sequence, one end of the first cylinder 101, which is far away from the second cylinder 102, is closed, and the surface of one end of the first cylinder 101 is provided with a plurality of resistors 12 and a plurality of bonding pads 8 which are electrically connected with the resistors 12;

a lead element 3, the lead element 3 being located within the housing 2 and connected to the first cylinder 101 of the sensor 1;

and the conductive curved pin 5 is inserted in the lead element 3, one end of the conductive curved pin 5 is electrically connected to the conductive pin 6, and the other end of the conductive curved pin 5 is electrically connected to the pad 8.

According to the pressure sensor, the lead element 3 is used for replacing a circuit board to communicate the bonding pad 8 of the sensitive element 1 with an external cable, so that the high temperature resistance of the sensor is greatly improved; the invention effectively solves the contradiction between multiple harsh requirements such as high precision, medium and high pressure, small volume, high frequency response, long service life, high reliability and the like under the environmental pressure measurement requirements of various high-temperature or wide-temperature areas, and is suitable for various occasions of high-pressure measurement in high-temperature environments in the fields of industry, aerospace and military industry.

As shown in fig. 1 to 3, the sensing element 1 and the housing 2 are both made of martensitic stainless steel or high-temperature alloy, the housing 2 includes a first cylinder section 201, a second cylinder section 202 and a third cylinder section 203 which are sequentially communicated, the first cylinder section 201 is in a hexagonal cylinder shape, one end of the first cylinder section 201 is closed and is provided with a plurality of pinholes 14, and each conductive needle 6 penetrates through one pinhole 14; the outer wall of the second cylinder section 202 is provided with external threads 10, and the outer diameter of the third cylinder section 203 is smaller than that of the second cylinder section 202;

the second cylinder 102 is inserted into the third cylinder section 203, and the end surface of the second cylinder 102 is aligned with the end surface of the third cylinder section 203.

The shell 2 is arranged on the sensing element 1, and the end face of one end of the second cylinder 102 of the sensing element 1, which is far away from the first cylinder 101, and the end face of one end of the third cylinder section 203 of the shell 2, which is far away from the first cylinder section 201, are in the same plane, so that when the sensor is arranged and used, a squeezing sealing mode is adopted between the plane and a use occasion interface plane.

Preferably, the sensing element 1 and the housing 2 are hermetically connected by welding, such as laser welding, argon arc welding, electron beam welding, or other fusion welding methods.

Adopt laser welding to weld sensing element 1 and shell 2 as an organic whole, the welding seam both can guarantee structural strength, does not take place relative motion under sensor installation pretightning force and medium pressure effect, can make again between sensing element 1 and the shell 2 not have the gap, and inside gas and other foreign matter can not get into the sensor from the junction, realize sealedly.

The sensing element 1 is made of an elastic membrane, when the working temperature is not more than 300 ℃, the sensing element 1 and the shell 2 usually use martensitic stainless steel with high strength and corrosion resistance, and when the temperature is higher, high-temperature alloy is adopted, and the high-temperature alloy can be selected according to the use requirement.

As shown in fig. 1 and 2, the outer wall of the second cylinder section 202 of the housing 2 is provided with the external thread 10, so that the volume of the sensor can be greatly reduced by reducing the height of the sensor, the cavity in the sensing element 1 has a larger diameter-depth ratio, and the sensor has a higher frequency response; the outer cylindrical surface of the first cylinder section 201 is hexagonal cylinder, which has six sides and rounded corners, and the outer cylindrical surface of the first cylinder section 201 may also be square or cylindrical. The first, second and third cylinder sections 201, 202 and 203 form a mounting space inside, and the mounting space is stepped. The conductive pin 6 penetrates the first barrel section 201 to the inside of the housing 2, and is arranged axially parallel to the housing 2.

The first cylinder 101 and the second cylinder 102 are internally spliced into a cylindrical cavity, when in use, the first cylinder 101 of the sensing element 1 is arranged in the shell 2, and pressure to be detected acts on the inner side surface of the first cylinder 101.

As shown in fig. 7, the outer circumference of the first cylinder 101 is provided with a notch 9, the notch 9 is not communicated with the cylindrical cavity, the notch 9 is parallel to the central axis of the first cylinder 101, and the notch 9 makes the first cylinder 101 form a cutting surface which is parallel to the axial direction of the first cylinder 101; the lead element 3 is made of ceramic, austenitic stainless steel or high temperature alloy, and includes a connection plate 301 and a complementary circular plate 302 extending from the connection plate 301, wherein the complementary circular plate 302 is disposed at the notch 9 and is complementary to the notch 9.

Preferably, the lead element 3 is made of ceramic, and can be applied to a temperature environment exceeding 200 ℃.

In other embodiments of the present application, the lead element 3 may also be made of austenitic stainless steel or a high temperature alloy, so as to be suitable for a temperature environment around 200 ℃, in which the use of austenitic stainless steel or high temperature alloy is more economical than the use of ceramics.

As shown in fig. 5 and 6, the connecting plate 301 of the lead element 3 is formed by cutting a cylinder parallel to the axial direction thereof, the connecting plate 301 may be a large circular segment, a small circular segment or a semicircle, and a part of the circular plate is cut in the thickness direction, so as to avoid the operation when the wire bending needle 5 and the bonding pad 8 are welded; the plenary plate 302 is also formed by cutting a cylinder parallel to the axial direction thereof, the plenary plate 302 is a small circular cut circle, and the plenary plate 302 is clamped at the notch 9 and forms a complete circle with the outer periphery of the first cylinder 101.

As shown in fig. 4 and 5, the pressure sensor further includes a hoop 4, the hoop 4 is sleeved on the outer peripheries of the first cylinder 101 and the complement plate 302, and contacts with the outer periphery of the first cylinder 101 of the sensing element 1, so as to fasten the complement plate 302 with the first cylinder 101;

the first cylinder 101 has an outer diameter smaller than the outer diameter of the second cylinder 102 and the hoop 4 has an outer diameter equal to the outer diameter of the second cylinder 102.

The hoop 4 is of a circular ring structure, the outer diameter of the first cylinder 101 is smaller than that of the second cylinder 102 to form a step, a clamping table 17 is arranged on the inner wall of the shell 2, one end of the hoop 4 is clamped on the step, the other end of the hoop is clamped on the clamping table 17, the hoop 4 is enabled to axially compress the first cylinder 101 and the lead element 3, it is ensured that the sensitive element 1 and the lead element 3 are still firmly fixed under the influence of mechanical environments such as vibration, impact, acceleration and thermal expansion and contraction of a thermal environment, and the lead element 3 is used for fixing the conductive bent needle 5.

Preferably, the hoop 4 and the outer wall of the sensing element 1 can be welded together by welding methods such as laser welding, so that the internal structure of the sensor is firmer.

Two resistor pairs are arranged on one end surface of the first cylinder 101 of the sensing element 1, each resistor pair comprises a pair of resistors 12 connected in series, and the resistor pairs are mutually and electrically connected to form a Wheatstone bridge;

the pad 8 is electrically connected to the terminal of the resistor 12, and the pad 8 is disposed away from the notch 9.

In one embodiment of the present application, as shown in fig. 8, the two resistor pairs are symmetrically distributed.

In other embodiments of the present application, the two resistor pairs are axially symmetrically distributed along the diameter direction of the first cylinder 101, and the diameter direction is parallel to the gap 9 of the first cylinder 101, the symmetry axis is perpendicular to the diameter direction of the two resistor pairs, there is one resistor pair on each side of the symmetry axis, and each resistor pair contains two resistors 12.

Because the stress surface of the pressure sensor, that is, the inner surface of one end of the first cylinder 101, is uniformly stressed, the arrangement of the resistor pairs may not be symmetrical or limited, and is determined according to the actual situation.

At least one compensation resistor 13 is further arranged on one end surface of the first cylinder 101 of the sensing element 1, and the compensation resistor 13 is electrically connected to a Wheatstone bridge and used for bridge zero point compensation;

the resistor 12 and the compensation resistor 13 are both thin film resistors.

As shown in fig. 9, the wheatstone bridge has four terminals, where terminals a (a) and d are a positive power supply terminal and a negative power supply terminal, terminals c (a) and d are a positive power supply terminal and a negative power supply terminal, respectively, terminals a (a) and (b) are open terminals, and have two connection points, two leading-out terminals of the compensation resistor 13 are connected to the two connection points, respectively, and the serial position of the compensation resistor 13 is adjusted according to the actual situation and the test result, so that the terminal a is used as the positive output terminal or the terminal a is used as the negative output terminal, thereby making the potential difference between the positive output terminal and the negative output terminal close to 0.

As shown in fig. 3, the conductive pins 6 have insertion holes 15 at one end thereof in the housing 2, the conductive curved pins 5 include a vertical portion and a horizontal portion bent from one end of the vertical portion, the horizontal portion of each conductive curved pin 5 is electrically connected to one pad 8 via a gold wire 7, and the other end of the vertical portion of each conductive curved pin 5 is inserted into one insertion hole 15.

The conductive curved pin 5 and the conductive pin 6 can be made of high-temperature alloy, and gold is plated after sintering and fixing. The gold thread 7 adopts a standard product commonly found in the market.

The vertical part of the conductive curved needle 5 coincides with the axis of the insertion hole 15 and is matched with the shaft hole, the vertical part of the conductive curved needle 5 is parallel to the axial direction of the first cylinder 101, and the horizontal part is perpendicular to the axial direction of the first cylinder 101.

When the shell 2 is installed, the inserting hole 15 of the conductive pin 6 of the shell 2 is sleeved on the conductive curved pin 5 of the lead element 3, so that the conductive performance is ensured by firm extrusion contact, and the stability of the lead element 3 is improved, so that the lead element 3 can resist the influence of mechanical environment and thermal environment more easily.

Preferably, the inlet of the insertion hole 15 may be provided with a bell mouth structure, so that the conductive bent pin 5 is easy to assemble when the axis of the vertical part and the axis of the insertion hole 15 are not completely perpendicular due to accumulation of processing and assembling errors.

As an alternative, the diameter of the insertion hole 15 may be larger than the diameter of the vertical portion of the conductive curved pin 5, and a plurality of spring pieces are arranged in the insertion hole 15 and arch up to the inner axis of the hole and around the circumference of the hole, so that the assembly is easy, and when the conductive curved pin 5 is inserted into the insertion hole 15, the spring pieces are tightly pressed on the periphery of the conductive curved pin 5 along the circumferential direction of the conductive curved pin 5 due to the elastic force, thereby achieving good electrical contact.

The surface of the bonding pad 8 of the sensitive element 1, the surface of the conductive pin 6 and the surface of the conductive bent pin 5 are plated with gold layers. The bonding pad 8, the conductive pin 6 and the conductive bent pin 5 are plated with gold and connected by a gold wire 7, so that the corrosion of the environmental atmosphere can be prevented, the service life is prolonged, and the reliability is improved. The bonding pad 8, the conductive bent needle 5 and the gold wire 7 are fixed through gold wire ball bonding. The gold wire ball bonding process is mature and efficient, is suitable for batch production, and is convenient for batch production of the sensor.

In other embodiments of the present application, the sensing element 1 and the conductive curved pin 5 can adopt a high-temperature manual brazing method which is convenient for small-scale production; the lead is welded with the pad 8 of the sensitive element 1 and the conductive bent needle 5 by adopting high-melting point brazing material and using equipment such as a high-temperature soldering iron, a flame welding gun or a hot oven, so that the conduction between the pad 8 of the sensitive element 1 and the conductive bent needle 5 is realized.

In one embodiment of the present application, the number of the pads 8 is five, and the pads are arranged in an arc shape and located below the cut portion of the connection board 301, so as to facilitate the processing.

The number of the conductive bent pins 5 is four, each conductive bent pin 5 is electrically connected with one bonding pad 8 through one gold wire 7, part of the bonding pads 8 on the sensing element 1 are connected with the conductive bent pins 5 on the lead element 3 through the gold wires 7, the inserting holes 15 of the conductive pins 6 of the shell 2 are sleeved on the vertical part of the conductive bent pins 5 on the lead element 3, the resistors 12 on the sensing element 1 form a Wheatstone bridge, the conductive pins 6 exposed on the shell 2 output zero-point signals outwards, and when media fill the cavity in the sensing element 1 and act on the inner surface of the first cylinder 101 of the sensing element 1, the sensor outputs signals proportional to pressure.

In one embodiment of the present application, a three-proofing protective layer may be coated on the surface of the sensitive element 1, and in particular, the three-proofing protective layer is disposed on one end surface of the first cylinder 101 for waterproofing, dust-proofing and antistatic the resistor 12 and the pad 8. Under the severe environment, such as damp and heat, frosting pollution and the like, the sensor can be damaged, so that the surface of the elastic membrane of the sensitive element 1 is subjected to three-proofing treatment, high-precision measurement can be stably realized for a long time under the severe environment, and the material of the three-proofing protective layer can be selected according to the working temperature and the specific environment, such as organic silicon three-proofing paint or polyurethane three-proofing paint and the like. The material of the three-proofing protective layer is selected to be suitable for the working temperature, so that the capability of resisting the corrosion of the environmental atmosphere on the surface of the sensitive element is improved.

In other embodiments of the present application, the inside of the housing 2 may be vacuumized to make the sensing element 1 in a vacuum environment, in which case, the surface of the sensing element 1 may not be provided with a three-proofing protective layer.

Pressure sensor still includes gasket 11, and the other end of shell 2 is equipped with aspirating hole 16, and aspirating hole 16 is the shoulder hole, including big footpath section and path section, and big footpath section is close to the other end surface of shell 2, and gasket 11 sealing connection is in the shoulder hole, and does not bulge in the surface of the other end of shell 2. The sealing plate 11 is connected with the shell 2 through welding.

Sealing piece 11 is connected in the major diameter section of shoulder hole, with the cooperation of 16 shaft holes in aspirating hole, the exposed one end of sealing piece 11 flushes with 2 surfaces of shell, and the shoulder hole both can make the inside gas of sensor discharge fast under vacuum environment, can regard as the plummer of sealing piece 11 again for inside sealing piece 11 can not fall into the sensor, shell 2 flushes with 11 surfaces of sealing piece and is convenient for implement the welding.

In an embodiment of the application, weld sealing plate 11 and shell 2 through vacuum electron beam welding, at first need place the sensor in the vacuum chamber that electron beam welded, the inside gas outgoing of sensor can be realized simultaneously to the evacuation process, uses electron beam with sealing plate 11 and shell 2 welded fastening back, and the welding seam has the sealing effect equally, takes out the sensor from the vacuum chamber after, the inside vacuum environment that forms of sensor.

In other embodiments of the present application, the sensor is placed in a vacuum chamber, after the internal gas is exhausted, vacuum grease is coated on the contact surface between the sealing sheet 11 and the housing 2, or a sealing pad is provided, a certain pressure is applied to the sealing sheet 11 by using a tool, and after the sensor is taken out from the vacuum chamber, the sealing sheet 11 and the housing 2 are fixedly sealed by using laser welding.

The interior of the sensor is kept in a vacuum state through the air exhaust hole 16, so that the interior material of the sensor is not corroded by various environmental gas components, and the phenomenon that the indication value of the sensor drifts along with the temperature or the measurement precision is reduced due to the temperature influence of the interior gas state is avoided.

When the pressure sensor of this application used, the sensor passed through external screw thread 10 on the shell 2 and installed on using the end interface, can adopt the raw material area to seal or sealed the pad seal according to using the end interface shape, and the raw material area or the sealed pad of polytetrafluoroethylene that use commonly used generally are used for below 300 ℃, should use the metal packing pad or the lug weld on the pressure-measuring pipeline during higher temperature. The electric part adopts a crimping contact pin with a hole to connect with an exposed conductive pin 6 on the shell 2, the other end is connected with a crimping lead to connect with a test instrument and meter, an electric signal is output, when a medium is led into the cavity of the sensitive element 1 to form pressure and the upper surface of the sensitive element 1 is deformed, the sensor outputs an electric signal which is approximately in linear relation with the applied pressure.

The sensor of the invention greatly reduces the volume of the sensor by arranging the external thread 10 on the shell 2, connects the sensing element 1 and the lead element 3 by the gold thread 7 for gold wire ball bonding, avoids using common tin solder, the pad 8 of the sensing element 1 adopts gold plating protection, the lead element 3, the conductive bent pin 5 and the conductive pin 6 of the shell 2 are fixed in the corresponding holes by a glass powder sintering method, can ensure the fixing strength and resist high temperature and sealing performance, the surfaces of the conductive bent pin 5 and the conductive pin 6 are plated with gold, ensure that the lead and lead welding points can resist high temperature far exceeding 200 ℃, and the chemical and physical conductivity can be kept stable, the shell 2 and the sensing element 1 are fixed and sealed by laser welding, the shell 2 and the sealing sheet 11 are fixed and sealed by electron beam welding in a vacuum environment, thereby not only keeping the vacuum state in the sensor for a long time, but also ensuring that the sensing element 1 and each electrical connection point are not slowly corroded by various environmental gas components, the pressure measurement value is not slowly drifted or the precision is not reduced due to the change of the internal sealed gas state under the condition of the environmental temperature under the vacuum state, meanwhile, the welding strength can be ensured by laser welding and electron beam welding, the strength requirement of the structure when bearing the installation pretightening force and the test pressure is met, the excellent test precision and the excellent temperature drift performance under the uncompensated state can be realized by the structural characteristics of the sensitive element 1 and the film resistor, the better diameter-depth ratio of the inner cavity of the sensitive element 1 can ensure the frequency response requirement under most application environments; the invention effectively solves the contradiction between multiple harsh requirements such as high precision, medium and high pressure, small volume, high frequency response, long service life, high reliability and the like under the environmental pressure measurement requirements of various high-temperature or wide-temperature areas, and is suitable for various occasions of high-pressure measurement in high-temperature environments in the fields of industry, aerospace and military industry.

The invention also provides a manufacturing method of the pressure sensor, which comprises the following steps:

step 1: manufacturing a first cylinder 101 and a second cylinder 102 of the sensitive element 1, and forming a resistor 12, a bonding pad 8 and an embedded connecting wire for electrically connecting the resistor 12 and the bonding pad 8 on one end surface of the first cylinder 101 by using a sputtering film process;

step 2: manufacturing a lead element 3, a shell 2, a conductive curved pin 5 and a conductive pin 6, sintering the conductive curved pin 5 on the lead element 3 and sintering the conductive pin 6 on the other end of the shell 2 by adopting a glass powder sintering process;

and step 3: connecting the lead element 3 to the first cylinder 101 of the sensitive element 1, and electrically connecting the bonding pad 8 of the sensitive element 1 and the conductive bent pin 5 by gold wire ball bonding;

and 4, step 4: inserting a conductive curved needle 5 into a conductive needle 6 to form contact conduction, sleeving a shell 2 on a sensitive element 1, and welding, fixing and sealing the sensitive element 1 and the shell 2 by welding;

and 5: and (3) placing the pressure sensor in a vacuum environment for a preset time, pumping out the gas between the shell 2 and the sensitive element 1, sealing the shell 2, and taking out the pressure sensor from the vacuum environment.

The sensitive element 1 is manufactured by adopting a sputtering film process in the step 1, so that miniaturization is easier to realize, the using temperature range is wide, the working and low-temperature drift characteristics of a wide temperature zone are ensured, the temperature performance of the full temperature zone is very excellent when the temperature is not compensated, for example, the zero drift value of the full temperature zone is mostly within 3 percent FS/even within 2 percent FS/within-50 ℃ to 250 ℃, and the temperature can be further improved by temperature compensation; the normal temperature precision of the sensor can reach 0.2% FS even within 0.1% FS; the diameter of the sensor can reach 10mm or less, the thread of the shell reaches M10 multiplied by 1 or less, and the total height of the sensor can reach 20mm or less; the diameter-depth ratio of the cavity of the sensitive element can reach about 1, the natural frequency of the pressure sensing surface of the sensitive element of the sensor can reach more than tens of kHz, and the effective frequency response of the sensor can reach several kHz and even more than ten kHz.

In step 2, each conductive curved pin 5 is sintered in a corresponding hole on the lead element 3 by a glass powder sintering process, and each conductive pin 6 is sintered in a corresponding pin hole 14 on the housing 2 so as to be fixed.

In step 3, the hoop 4 is sleeved outside the first cylinder 101 of the sensing element 1, and the supplementary circular plate 302 of the lead element 3 is inserted into a gap between the first cylinder 101 and the hoop 4 to supplement the gap 9; a first point is bonded to the terminal pad 8 of the bridge of the sensor 1 by gold ball bonding, and then a second point is bonded to the end of the conductive bent pin 5 of the lead member 3.

In the step 4, the shell 2 is installed, the conductive pins 6 are sleeved on the conductive bent pins 5 on the lead element 3 one by one to form contact conduction, meanwhile, the shell 2 is sleeved on the sensitive element 1, and the sensitive element 1 and the shell 2 are welded, fixed and sealed by adopting welding modes such as laser welding and the like.

In step 5, after the gas between the shell 2 and the sensitive element 1 is pumped out, the sealing sheet 11 is arranged at the position of the pumping hole 16 on the shell 2, the shell 2 and the sealing sheet 4 are welded, fixed and sealed by adopting vacuum electron beam welding, and the sensor is taken out from a vacuum environment for integral debugging and testing.

In other embodiments of the present application, when the pressure sensor is not vacuumized, a three-proofing protection layer may be applied to one end surface of the first cylinder 101 of the sensing element 1, that is, a three-proofing protection layer is uniformly coated on the surface of the pad 8 of the sensing element 1 and cured to protect the pad 8 and the resistor 12.

The method for manufacturing the pressure sensor is mature in technology, convenient, fast and easy, and is very suitable for batch production in a mechanized and assembly line mode.

All processing and manufacturing methods adopted by the whole sensor are mature and easy, and the sputtering film process used for processing and manufacturing the sensitive element 1 is quite suitable for mass production in a mechanized and flow line mode. The rest parts can be realized through the traditional machining process, the sintering process, the integrated circuit packaging, welding, assembling process and the like, the relative bottleneck is manual assembling, debugging and testing tests, and the problems of manual welding, assembling, debugging and testing tests can be solved through electric tools, special tools and welding equipment which are widely used in the mature common sensor production line. The whole scheme can be divided according to the procedures of the production flow of the mature sensor in the process, and an appropriate number of assembly tools and calibration and test inspection tools are configured according to the required scale to realize batch production.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (10)

1. A pressure sensor, comprising:

the shell (2), the said shell (2) is a tube shape that one end is open, another end is closed;

a plurality of conductive pins (6), wherein the conductive pins (6) are inserted into the other end of the shell (2) in parallel with the axial direction of the shell (2);

the sensing element (1) is arranged in the shell (2) and comprises a first cylinder (101) and a second cylinder (102) which are communicated in sequence, one end of the first cylinder (101) departing from the second cylinder (102) is closed, and the surface of one end of the first cylinder (101) is provided with a plurality of resistors (12) and a plurality of bonding pads (8) electrically connected with the resistors (12);

-a lead element (3), said lead element (3) being located inside said casing (2) and being connected to said first cylinder (101) of said sensitive element (1);

the lead element comprises a lead element (3), a conductive curved needle (5), wherein the conductive curved needle (5) is inserted into the lead element (3), one end of the conductive curved needle (5) is electrically connected to the conductive needle (6), and the other end of the conductive curved needle (5) is electrically connected to the pad (8).

2. A pressure sensor according to claim 1, wherein the sensing element (1) and the housing (2) are made of martensitic stainless steel or high temperature alloy, the housing (2) comprises a first cylinder section (201), a second cylinder section (202) and a third cylinder section (203) which are communicated in sequence, the first cylinder section (201) is in a hexagonal cylinder shape, one end of the first cylinder section (201) is closed and is provided with a plurality of needle holes (14), and each conductive needle (6) penetrates through one needle hole (14); an external thread (10) is arranged on the outer wall of the second cylinder section (202), and the outer diameter of the third cylinder section (203) is smaller than that of the second cylinder section (202);

the second cylinder (102) is inserted into the third cylinder section (203).

3. A pressure sensor according to claim 2, characterized in that the outer circumference of the first cylinder (101) is provided with a notch (9), the notch (9) being parallel to the central axis of the first cylinder (101), the lead element (3) being made of ceramic, austenitic stainless steel or a high temperature alloy, comprising a connection plate (301) and a complementary plate (302) protruding from the connection plate (301), the complementary plate (302) being provided at the notch (9) and complementing the notch (9).

4. A pressure sensor according to claim 3, characterized by further comprising a hoop (4), wherein the hoop (4) is sleeved on the outer peripheries of the first cylinder (101) and the plenary plate (302) and is in contact with the outer periphery of the first cylinder (101) of the sensing element (1);

the first cylinder (101) has an outer diameter smaller than the outer diameter of the second cylinder (102), and the hoop (4) has an outer diameter identical to the outer diameter of the second cylinder (102).

5. A pressure sensor according to claim 3, characterized in that said one end surface of said first cylinder (101) of said sensor element (1) is provided with two pairs of resistors, each pair comprising a pair of said resistors (12) connected in series, said pairs being electrically connected to each other to form a wheatstone bridge;

the bonding pad (8) is electrically connected with a leading-out end of the resistor (12), and the bonding pad (8) is far away from the notch (9).

6. Pressure sensor according to claim 5, characterized in that said one end surface of said first cylinder (101) of said sensing element (1) is further provided with at least one compensation resistor (13), said compensation resistor (13) being electrically connected to said Wheatstone bridge for bridge zero compensation;

the resistor (12) and the compensation resistor (13) are both thin film resistors.

7. A pressure sensor according to claim 1, characterized in that the surface of the pad (8), the surface of the conductive pin (6) and the surface of the conductive bent pin (5) of the sensor (1) are plated with a gold layer.

8. The pressure sensor according to claim 1, wherein one end of the conductive pin (6) in the housing (2) is provided with an insertion hole (15), the conductive curved pin (5) comprises a vertical part and a horizontal part bent from one end of the vertical part, the horizontal part of each conductive curved pin (5) is electrically connected to one of the pads (8) through a gold wire (7), and the other end of the vertical part of each conductive curved pin (5) is inserted into one of the insertion holes (15).

9. The pressure sensor according to claim 1, further comprising a sealing plate (11), wherein the other end of the housing (2) is provided with a pumping hole (16), the pumping hole (16) is a stepped hole, and the sealing plate (11) is connected in the stepped hole in a sealing manner and does not protrude from the surface of the other end of the housing (2).

10. A method of making a pressure sensor according to any of claims 1 to 9, the method comprising:

step 1: manufacturing the first cylinder (101) and the second cylinder (102) of the sensitive element (1), and forming the resistor (12), the pad (8) and a buried connecting wire for electrically connecting the resistor (12) and the pad (8) on one end surface of the first cylinder (101) by using a sputtering film process;

step 2: manufacturing the lead element (3), the shell (2), the conductive bent pin (5) and the conductive pin (6), sintering the conductive bent pin (5) on the lead element (3) and sintering the conductive pin (6) on the other end of the shell (2) by adopting a glass powder sintering process;

and step 3: connecting the lead element (3) to a first cylinder (101) of the sensitive element (1), and electrically connecting the bonding pad (8) of the sensitive element (1) and the conductive bent pin (5) by using gold wire ball bonding;

and 4, step 4: inserting the conductive curved needle (5) into the conductive needle (6) to form contact conduction, sleeving the shell (2) on the sensitive element (1), and welding, fixing and sealing the sensitive element (1) and the shell (2) by welding;

and 5: and placing the pressure sensor in a vacuum environment for a preset time, pumping out gas between the shell (2) and the sensitive element (1), sealing the shell (2), and taking out the pressure sensor from the vacuum environment.

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