CN212409938U

CN212409938U - MEMS pressure sensor oil-filled core

Info

Publication number: CN212409938U
Application number: CN202021071699.8U
Authority: CN
Inventors: 王小平; 曹万; 李凡亮; 王红明; 施涛; 吴登峰; 李兵
Original assignee: Wuhan Finemems Inc
Current assignee: Wuhan Finemems Inc
Priority date: 2020-06-11
Filing date: 2020-06-11
Publication date: 2021-01-26
Anticipated expiration: 2030-06-11

Abstract

The utility model relates to the technical field of pressure sensors, and discloses an oil-filled core body of an MEMS pressure sensor, which comprises an upper cover, a base and a sensitive component; the lower end of the upper cover is hermetically connected with the base, the base and the upper cover form a sealed cavity, and a detection medium is filled in the sealed cavity; and a sensitive component is arranged on the base and positioned in the sealed cavity. This MEMS pressure sensor oil charge core adopts silicon elastic diaphragm and semiconductor resistor and the chip that the signal calibration module constitutes, the outside need not to set up signal processing circuit, lead wire interconnection is few, moreover, the steam generator is simple in structure, and is with low costs, the product reliability is high, the production of being convenient for, and semiconductor resistor and signal calibration module are located different planes, and the signal calibration module is located around the silicon elastic diaphragm, avoid silicon elastic diaphragm's stress variation to influence the signal calibration module, lead to the impaired risk of circuit among the signal calibration module, be favorable to guaranteeing the precision.

Description

MEMS pressure sensor oil-filled core

Technical Field

The utility model relates to a pressure sensor technical field specifically is a MEMS pressure sensor oil charge core.

Background

The pressure sensor mainly has the function of converting an external pressure signal into an electric signal, and is widely applied to the fields of automotive electronics, aerospace, petrochemical industry, medical appliances, consumer electronics and the like.

The pressure chip is used as a core device of the pressure sensor and mainly can be divided into pressure sensors of diffused silicon piezoresistive type, capacitive type, piezoelectric type, resonant type and the like; the pressure-sensitive element is manufactured in the pressure-sensitive membrane area by an ion implantation mode; in addition, the MEMS pressure sensor has small volume, light weight, low cost, high sensitivity, wide application environment and different requirements on the packaging modes of the MEMS pressure sensor by different application environments, and the oil-filled cores of the pressure sensors with different packaging modes are published for meeting the medium compatibility of the sensors; the prior oil-filled core packaging mode is difficult to get rid of the defects of high product cost, complex manufacturing process, low precision, poor reliability and the like, and the patent CN106768592A discloses 'a pressure transmitter oil-filled core with a signal processing function', wherein a base is a high-pressure sintering seat, the base body is machined and manufactured, the machining efficiency is low, the cost is high, the manufacturing process cannot be compatible with the mature semiconductor packaging process, such as automatic high-speed paster and full-automatic high-speed lead bonding, in addition, the temperature measurement module, the signal processing unit and the pressure sensing unit are arranged on the same working surface, and because the pressure sensing unit belongs to the weakest region of a sensor chip and continuously deforms along with the pressure change, the signal processing unit is also arranged on the working surface, the internal microcircuit faces the risk of fatigue damage; in the medium isolation type pressure sensor packaging structure disclosed by the patent CN1056343A, a pressure sensor packaging module is arranged in an oil filling cavity, the packaging module cannot ensure that no gas remains in the sealed cavity due to the moisture absorption of the material and the existence of air holes, and meanwhile, the output temperature drift of the pressure sensor is increased due to the excessive filling volume of the internal silicone oil, so that the precision of the sensor is reduced; patent CN208721309U has announced "a simple and easy oil-filled core", paste the direct riveting of tube shell that has the pressure chip, and this process leads to the huge stress of tube shell product, and stress transfer to pressure chip to cause sensor output drift, uniformity and precision degrade, in addition, the inside sealing washer that is provided with the thermal expansion coefficient far surpasses the silicon chip of seal chamber, causes the output temperature drift of sensor increase sensor under high low temperature condition.

SUMMERY OF THE UTILITY MODEL

Technical problem to be solved

To prior art not enough, the utility model provides a MEMS pressure sensor oil charge core possesses the oil charge core and detects advantages such as precision height, has solved prior art in temperature measurement module, signal processing unit and pressure sensing unit setting at same working face, because the pressure sensing unit belongs to the sensor chip weakest and constantly takes place deformation region along with pressure variation, signal processing unit also sets up the risk that will make the inside microcircuit of chip face fatigue damage here, the problem that makes the sensor precision reduce.

(II) technical scheme

For realizing the high purpose of above-mentioned oil charge core detection precision, the utility model provides a following technical scheme: an oil-filled core body of an MEMS pressure sensor comprises an upper cover, a base and a sensitive component;

the lower end of the upper cover is hermetically connected with the base, the base and the upper cover form a sealed cavity, and a detection medium is filled in the sealed cavity;

a sensitive component is arranged on the base and positioned in the sealed cavity; the sensitive assembly comprises a silicon elastic membrane and a signal calibration module which are positioned on the same plane;

the signal calibration module is positioned around the silicon elastic membrane;

and the silicon elastic membrane is provided with a semiconductor resistor.

Preferably, the upper surface of the base is provided with a patch adhesive and positioning marks, the patch adhesive is used for adhering the sensitive components, and the positioning marks are distributed on the periphery of the patch adhesive.

Preferably, a back pressing sheet is further arranged between the patch glue and the sensitive component.

Preferably, the center that the paster was glued is equipped with the round hole, the lower surface of base is equipped with the through-hole with the round hole intercommunication.

Preferably, the base is further provided with a pin, the pin is provided with a lead electrically connected with the sensitive component, and the joint of the pin and the base is provided with sintered glass.

Preferably, the base is further provided with a filling hole, and the lower surface of the base is located in the filling hole and connected with a steel ball.

Preferably, a first welding ring with a conical section is arranged on a contact surface of the base and the lower end of the upper cover in sealing connection.

Preferably, the upper cover includes ring, pressure diaphragm and shell, be equipped with the second welding circle on the shell, the shell passes through the second welding circle and the ring is connected, the pressure diaphragm is located between shell and the ring, pressure diaphragm and shell are the metal of same model.

Preferably, the upper surface of the shell is provided with a pressure-resistant blocking groove, and the lower surface of the shell is provided with a medium groove; the medium groove is communicated with the overpressure blocking groove.

(III) advantageous effects

Compared with the prior art, the utility model provides a MEMS pressure sensor oil charge core possesses following beneficial effect:

1. this MEMS pressure sensor oil charge core adopts silicon elastic diaphragm and semiconductor resistor and the chip that the signal calibration module constitutes, the outside need not to set up signal processing circuit, lead wire interconnection is few, moreover, the steam generator is simple in structure, and is with low costs, the product reliability is high, the production of being convenient for, and semiconductor resistor and signal calibration module are located different planes, and the signal calibration module is located around the silicon elastic diaphragm, avoid silicon elastic diaphragm's stress variation to influence the signal calibration module, lead to the impaired risk of circuit among the signal calibration module, be favorable to guaranteeing the precision.

2. According to the oil-filled core body of the MEMS pressure sensor, the circular ring, the pressure membrane and the shell are made of metal of the same type, and are packaged by adopting all metal, so that the inside of the sealed cavity body is free of materials with stronger hygroscopicity and larger thermal expansion coefficient, such as PCBs, plastic parts and the like, and the inside of the sealed cavity body is prevented from generating bubbles, moisture and thermal deformation, so that the reliability and precision of a product are reduced.

3. According to the oil-filled core body of the MEMS pressure sensor, the medium filling amount in the sealed cavity is controlled to be the minimum volume, the smaller the medium filling volume is, the smaller the contraction and expansion amount of a product caused by the CTE of a medium material is under the high and low temperature change, and the improvement of the high and low temperature precision of the oil-filled core body of the MEMS pressure sensor is facilitated.

4. This MEMS pressure sensor oil charge core is equipped with paster gum and location sign through the upper surface of base, and paster gum is used for bonding sensitive subassembly, and the location sign distributes in paster gluey periphery, fixes a position, is convenient for realize high-speed automatic paster.

Drawings

Fig. 1 is a cross-sectional view of a first embodiment of an oil filled core structure of a MEMS pressure sensor according to the present invention.

Fig. 2 is a structural diagram of an upper cover in a first embodiment of an oil filled core of a MEMS pressure sensor according to the present invention.

Fig. 3 is a structural diagram of a base and a sensing assembly in a first embodiment of an oil filled core of a MEMS pressure sensor according to the present invention.

Fig. 4 is a structural diagram of a sensing assembly in a first embodiment of an oil filled core of a MEMS pressure sensor according to the present invention.

Fig. 5 is a top view of a base in a first embodiment of an oil filled core of a MEMS pressure sensor according to the present invention.

Fig. 6 is a cross-sectional view of a second embodiment of an oil filled core of a MEMS pressure sensor in accordance with the present invention.

Fig. 7 is a structural diagram of a sensing assembly in a second embodiment of an oil filled core of a MEMS pressure sensor according to the present invention.

In the figure: 10 upper cover, 20 base, 201 pin, 202 base upper surface, 203 first welding ring, 204 filling hole, 205 sintered glass, 206 positioning mark, 301 lead, 302 patch glue, 40 sensitive component, 41 silicon elastic diaphragm, 42 signal calibration module, 43 semiconductor resistor, 44 backpressure sheet, 510 through hole, 11 ring, 12 pressure diaphragm, 13 shell, 131 overpressure blocking groove, 132 medium groove, 14 second welding ring, 15 steel ball, 16 sealing cavity, 17 detection medium.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The first embodiment is as follows:

referring to fig. 1-5, an oil core of a MEMS pressure sensor includes an upper cover 10, a base 20, and a sensing assembly 40; the base 20 is provided with a sensitive component 40; the sensitive assembly 40 comprises a silicon elastic diaphragm 41 and a signal calibration module 42, wherein the silicon elastic diaphragm 41 and the signal calibration module 42 are both arranged on the die and positioned on the same horizontal plane; the signal calibration module 42 is positioned around the silicon elastic membrane 41; the silicon elastic membrane 41 is provided with the semiconductor resistor 43, so that the semiconductor resistor 43 and the signal calibration module 42 are located on different planes, and the signal calibration module 42 is located around the silicon elastic membrane 41, thereby avoiding the risk that the stress change of the silicon elastic membrane 41 affects the signal calibration module 42 to cause the damage of a circuit in the signal calibration module 42, and being beneficial to ensuring the precision; the principle is that the silicon elastic diaphragm 41 is stressed to generate strain, so that the resistance value of the semiconductor resistor 43 on the silicon elastic diaphragm is changed differently under the action of piezoresistive effect and anisotropy of the material, a voltage signal corresponding to a pressure value is output through the principle of a Wheatstone bridge, and the voltage signal is amplified, high-low temperature and linear compensated through a signal calibration module 42 integrated on a pressure chip and then outputs a voltage signal meeting the use requirement of a terminal;

the lower end of the upper cover 10 is hermetically connected with the base 20, the base 20 and the upper cover 10 form a sealed cavity 16, a detection medium 17 is filled in the sealed cavity 16 in a vacuum manner, the detection medium can be silicone oil, and the sensitive component 40 is positioned in the sealed cavity 16 and is in contact with the detection medium 17; the base 20 is also provided with a filling hole 204 for filling the sealing cavity 16 with a medium, and the lower surface of the base 20, which is positioned in the filling hole 204, is connected with a steel ball 15 for sealing; a first welding ring 203 with a conical section is arranged on the contact surface of the base 20 and the lower end of the upper cover 10 in a sealing connection manner, so that a uniform and compact welding surface can be formed during welding, and the sealing performance and the structural stability of the welding surface are ensured;

the base 20 is provided with pins 201, the joints of the pins 201 and the base 20 are provided with sintered glass 205, the sintered glass 205 is used for insulating and sealing the pins from the base 20, the pins 201 and the base 20 are made of metal, preferably Kovar with low CTE, and the surface layer is plated with gold; the base pin 201 is provided with a lead 301 electrically connected with the sensitive component 40, the connection is completed in a full-automatic thermosonic bonding mode, the lead 301 can be a gold wire, an aluminum wire or a copper wire, and the lead is preferably a gold wire; the upper surface 202 of the base 20 is provided with a patch adhesive 302 and positioning marks 206, the patch adhesive 302 is used for adhering the sensitive component 40, and the positioning marks 206 are distributed on the periphery of the patch adhesive 302 for positioning, so that high-speed automatic patch mounting is realized conveniently; a back pressure sheet 44 is arranged between the patch adhesive 302 and the sensitive component 40 to ensure the back pressure of the sensitive component 40;

the upper cover 10 comprises a circular ring 11, a pressure diaphragm 12 and a shell 13, wherein a second welding ring 14 is arranged on the shell 13, the shell 13 is connected with the circular ring 11 through the second welding ring 14, the pressure diaphragm 12 is positioned between the shell 13 and the circular ring 11, and the pressure diaphragm 12 is a flat diaphragm or a corrugated pressure diaphragm; the circular ring 11, the pressure diaphragm 12 and the shell 13 are all made of metal of the same type, preferably stainless steel of the same type, so that thermal stress caused by CTE mismatch among materials is eliminated, and reduction of output accuracy of the sensor is avoided;

the upper surface 202 of the housing 13 is provided with an overpressure blocking groove 131 to prevent the pressure diaphragm 12 from being deformed too much and damaged due to the overload of the external pressure; the lower surface of shell 13 is equipped with medium groove 132, and medium groove 132 is linked together with excessive pressure and blocks groove 131, and the groove depth of medium groove 132 can influence the volume of seal chamber 16, and then reduces the filling volume of medium 17, makes the medium keep at the minimum, avoids reducing the product output drift that medium 17 expend with heat and contract with cold and lead to.

Example two:

referring to fig. 6-7, the difference from the first embodiment is that there is no back pressure sheet between the patch adhesive 302 and the sensing assembly 40, and the center of the patch adhesive 302 is provided with a circular hole, and the lower surface of the base 20 is provided with a through hole 510 communicating with the circular hole, so that the oil-filled core is conducted with the atmosphere, and the measured value relative to the atmospheric pressure can be detected.

When in use:

(1) the external pressure acts on the pressure diaphragm 12, the medium 17 filled in the sealed cavity 16 is squeezed through the pressure diaphragm 12, and then the pressure is transmitted to the sensing assembly 40 through the medium 17, so that the change of the silicon elastic diaphragm 41 on the sensing assembly 40 is caused, the silicon elastic diaphragm 41 is subjected to the stress to generate strain, the resistance value of the semiconductor resistor 43 on the silicon elastic diaphragm is changed differently under the piezoresistive effect and the anisotropy of the material, and a voltage signal corresponding to the pressure value is output through the principle of a stoneway bridge.

(2) The circular ring 11, the pressure diaphragm 12 and the shell 13 are all made of metal of the same type, so that thermal stress caused by CTE mismatch among materials is eliminated, and reduction of output accuracy of the sensor caused by CTE mismatch is avoided.

When in use, the utility model is used,

in summary, compared with the prior art, the oil-filled core body of the MEMS pressure sensor adopts a chip composed of the silicon elastic diaphragm 41, the semiconductor resistor 43 and the signal calibration module 42, no signal processing circuit is required to be arranged outside, the interconnection of the lead wires 301 is less, the structure is simple, the cost is low, the product reliability is high, the semiconductor resistor 43 and the signal calibration module 42 are located on different planes, and the signal calibration module 42 is located around the silicon elastic diaphragm 41, so that the risk that the stress change of the silicon elastic diaphragm 41 affects the signal calibration module 42, which causes the circuit in the signal calibration module 42 to be damaged is avoided, and the accuracy is favorably ensured;

the circular ring 11, the pressure diaphragm 12 and the shell 13 are all made of metal of the same type, and are packaged by all metals, so that materials with stronger hygroscopicity and thermal expansion coefficients, such as a PCB (printed Circuit Board) and a plastic piece, are not arranged in the sealed cavity 16, and bubbles, moisture and thermal deformation generated in the sealed cavity are avoided, so that the reliability and the precision of a product are reduced;

the filling amount of the medium 17 in the sealed cavity 16 is controlled to be the minimum volume, the smaller the filling volume of the medium 17 is, the smaller the contraction and expansion amount of the product caused by the CTE of the medium material is correspondingly under the high and low temperature change, and the improvement of the high and low temperature precision of the oil-filled core of the MEMS pressure sensor is facilitated; the upper surface 202 of the base 20 is provided with the patch adhesive 302 and the positioning marks 206, the patch adhesive 302 is used for adhering the sensitive component 40, and the positioning marks 206 are distributed on the periphery of the patch adhesive 302 for positioning, so that high-speed automatic patch is realized conveniently; the problem of among the prior art with temperature measurement module, model processing unit and pressure sensing unit setting at same working face, because the pressure sensing unit belongs to the sensor chip weakest and constantly takes place the deformation region along with pressure variation, signal processing unit also sets up and will make the inside microcircuit of chip face fatigue damage at this face, make the sensor precision reduce is solved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a MEMS pressure sensor oil charge core which characterized in that: comprises an upper cover (10), a base (20) and a sensitive component (40);

the lower end of the upper cover (10) is hermetically connected with a base (20), the base (20) and the upper cover (10) form a sealed cavity (16), and a detection medium (17) is filled in the sealed cavity (16);

a sensitive component (40) is arranged on the base (20) and in the sealed cavity (16); the sensitive assembly (40) comprises a silicon elastic diaphragm (41) and a signal calibration module (42) which are positioned on the same plane;

the signal calibration module (42) is positioned around the silicon elastic membrane (41);

and a semiconductor resistor (43) is arranged on the silicon elastic membrane (41).

2. The MEMS pressure sensor oil filled core of claim 1, wherein: the upper surface (202) of the base (20) is provided with patch glue (302) and positioning marks (206), the patch glue (302) is used for adhering the sensitive component (40), and the positioning marks (206) are distributed on the periphery of the patch glue (302).

3. The MEMS pressure sensor oil filled core of claim 2, wherein: and a back pressing sheet (44) is also arranged between the patch adhesive (302) and the sensitive component (40).

4. The MEMS pressure sensor oil filled core of claim 2, wherein: the center of paster glue (302) is equipped with the round hole, the lower surface of base (20) is equipped with through-hole (510) with the round hole intercommunication.

5. The MEMS pressure sensor oil filled core of claim 1, wherein: still be equipped with pin (201) on base (20), be equipped with on pin (201) with sensitive subassembly (40) electrical connection's lead wire (301), the junction of pin (201) and base (20) is equipped with fritted glass (205).

6. The MEMS pressure sensor oil filled core of claim 1, wherein: the base (20) is further provided with a filling hole (204), and the lower surface of the base (20) is located in the filling hole (204) and connected with a steel ball (15).

7. The MEMS pressure sensor oil filled core of claim 1, wherein: and a first welding ring (203) with a conical section is arranged on the contact surface of the base (20) and the lower end of the upper cover (10) in sealing connection.

8. The MEMS pressure sensor oil filled core of claim 1, wherein: upper cover (10) include ring (11), pressure diaphragm (12) and shell (13), be equipped with second welding circle (14) on shell (13), shell (13) are connected through second welding circle (14) and ring (11), pressure diaphragm (12) are located between shell (13) and ring (11), pressure diaphragm (12) and shell (13) are the metal of same model.

9. The MEMS pressure sensor oil filled core of claim 8, wherein: the upper surface (202) of the shell (13) is provided with a pressure-resistant blocking groove (131), and the lower surface of the shell (13) is provided with a medium groove (132); the dielectric groove (132) is communicated with the overpressure blocking groove (131).