CN113532704A - Pressure sensor - Google Patents
Pressure sensor Download PDFInfo
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- CN113532704A CN113532704A CN202010292154.8A CN202010292154A CN113532704A CN 113532704 A CN113532704 A CN 113532704A CN 202010292154 A CN202010292154 A CN 202010292154A CN 113532704 A CN113532704 A CN 113532704A
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- ceramic
- pressure sensor
- pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
- G01L1/2287—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges constructional details of the strain gauges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
- G01L9/04—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of resistance-strain gauges
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- Measuring Fluid Pressure (AREA)
Abstract
The invention provides a pressure sensor which comprises a sensing module and a processing module, wherein the sensing module comprises a ceramic diaphragm and a measuring element, the processing module comprises a ceramic substrate and a processing element, the measuring element is installed on the upper surface of the ceramic diaphragm, the processing element is installed on the upper surface of the ceramic substrate, the upper surface of the ceramic diaphragm is sealed and connected with the lower surface of the ceramic substrate, the processing element is in communication connection with the measuring element, the measuring element is configured to generate corresponding resistance change when the ceramic diaphragm is deformed under stress and output the resistance change to the processing element in the form of an electric signal, and the processing element is configured to acquire corresponding pressure information according to the received electric signal. The pressure measuring device has the advantages of simple circuit structure, high reliability of pressure measurement and low manufacturing cost.
Description
Technical Field
The invention relates to the technical field of pressure measurement, in particular to a pressure sensor.
Background
A pressure sensor is the most common sensor in practice and is widely used in various fields. The pressure sensor is a device that converts a pressure of a medium into an electric signal and outputs the electric signal. The sensing element is an important part of the pressure sensor, can convert the medium pressure into an initial electric signal and transmit the initial electric signal to the processing element through the conductor, and the processing element acquires the medium pressure according to the electric signal. The sensing element with the ceramic as the base material has the advantages of high temperature resistance, strong medium corrosion resistance and good temperature stability, and is widely applied to pressure sensors.
Most of the existing ceramic sensing elements are ceramic capacitive sensing elements, and the technology has the following defects:
firstly, because the ceramic capacitive sensing element has high requirement on a dielectric medium, the capacitor needs to be sealed in an internal cavity, relative pressure cannot be measured, only absolute pressure can be measured, and the ceramic capacitive sensing element cannot be used in occasions where the relative pressure needs to be directly measured;
secondly, the ceramic capacitive sensing element has high requirements on a dielectric medium and needs high sealing performance, so that a processing chip and related protection elements need to be mounted on a separate circuit board, and the cost of raw materials of the sensor is high and the structure is complex;
and thirdly, a capacitance signal output by the ceramic capacitance type sensing element is transmitted to the circuit board and needs to be connected by a single wire, so that the process cost is high and the structure is complex.
Disclosure of Invention
In order to solve the above technical problems, the present invention provides a pressure sensor, which can measure both relative pressure and absolute pressure, and does not require a circuit board or separate wiring, thereby simplifying a circuit structure for pressure detection, improving reliability of pressure detection, and reducing cost of pressure detection.
The pressure sensor specifically comprises a sensing module and a processing module, wherein the sensing module comprises a ceramic diaphragm and a measuring element, and the processing module comprises a ceramic substrate and a processing element;
the measuring element is arranged on the upper surface of the ceramic diaphragm, the processing element is arranged on the upper surface of the ceramic substrate, the upper surface of the ceramic diaphragm is sealed with the lower surface of the ceramic substrate, and the processing element is in communication connection with the measuring element; wherein: the measuring element is configured to generate corresponding resistance change when the ceramic diaphragm is deformed under the stress, and the resistance change is output to the processing element in an electric signal mode; the processing element is configured to obtain corresponding pressure information from the received electrical signal.
Optionally, the pressure sensor further includes a conductive circuit, the conductive circuit includes a first conductive layer, a second conductive layer and a third conductive layer, and the first conductive layer, the third conductive layer and the second conductive layer are electrically connected in sequence;
the first conducting layer is integrated with the ceramic substrate and is electrically connected with the processing element; the second conducting layer is directly formed on the upper surface of the ceramic diaphragm and is electrically connected with the measuring element; the third conductive layer is formed directly inside the ceramic base.
Optionally, the first conductive layer includes a plurality of conductive lines, and a plurality of the conductive lines are printed on the upper surface of the ceramic substrate, or a plurality of the conductive lines are embedded inside the ceramic substrate. When the first conducting layer comprises a plurality of conducting wires, the conducting wires can be printed on the upper surface of the ceramic substrate or embedded in the ceramic substrate through a thick film printing process and a sintering curing process in sequence. When the first conductive layer comprises a plurality of leads, the leads can be printed on the upper surface of the ceramic substrate or embedded in the ceramic substrate by a high-temperature co-firing ceramic process. When the first conducting layer comprises a plurality of conducting wires, the conducting wires can be printed on the upper surface of the ceramic substrate or embedded in the ceramic substrate through a low-temperature co-firing ceramic process.
Optionally, the ceramic substrate has a through hole penetrating through upper and lower surfaces of the ceramic substrate, and the third conductive layer is disposed in the through hole.
Optionally, the third conductive layer is a conductive material, and the conductive material is filled in the through hole, or the third conductive layer is a wire, and the wire is fixed in the through hole.
Optionally, the measuring element is a wheatstone bridge, the second conductive layer includes a plurality of bridge leads and a plurality of bridge pads, two ends of each bridge arm of the wheatstone bridge are connected to one of the bridge leads, and each bridge lead is electrically connected to a corresponding one of the bridge pads;
the number of the through holes is consistent with that of the bridge pads, one third conducting layer is arranged in each through hole, and each bridge pad is electrically connected to one corresponding third conducting layer.
Optionally, the wheatstone bridge is printed on the upper surface of the ceramic diaphragm sequentially through a thick film printing process and a sintering curing process.
Optionally, the bridge leads are printed on the upper surface of the ceramic membrane sequentially through a thick film printing process and a sintering process.
Optionally, the conductive line further comprises a fourth conductive layer; the fourth conducting layer is directly formed on the upper surface of the ceramic substrate and is electrically connected with the processing element; the processing element is in communication connection with the outside through the fourth conductive layer.
Optionally, the fourth conductive layer includes a plurality of lead pads, and each of the lead pads is electrically connected to the processing element by a wire.
Optionally, the sensing module further comprises a compensation circuit disposed on the ceramic diaphragm or the ceramic substrate for biasing an output of the measurement element below a predetermined value when the ceramic diaphragm is not stressed.
Optionally, the measuring element is a wheatstone bridge, and the compensation circuit includes at least one compensation resistor, and at least one compensation resistor is connected in parallel or in series on at least one leg end of the wheatstone bridge.
Optionally, the processing module further comprises a passive element disposed on an upper surface of the ceramic substrate.
Optionally, the processing element comprises at least one processing chip, which is a package structure or a die.
Optionally, an accommodating space is formed between the ceramic substrate and the ceramic diaphragm, the accommodating space is centrally disposed, and the measuring element is located in the accommodating space.
Optionally, the accommodating space has at least one opening;
the ceramic diaphragm is configured such that a lower surface senses a first pressure of the medium and an upper surface senses a second pressure of the medium through the opening;
the measuring element is further configured to generate first resistance information when the lower surface of the ceramic diaphragm is subjected to the first pressure, and output the first resistance information to the processing element as a first electrical signal; the measuring element is further configured to generate second resistance information when the upper surface of the ceramic diaphragm is subjected to the second pressure, and output the second resistance information to the processing element as a second electrical signal;
the processing element is configured to obtain differential pressure information from the received first and second electrical signals.
Optionally, the accommodating space is a sealed space, a part of the upper surface of the ceramic membrane is sealed with the ceramic substrate, and the other part of the upper surface is located in the sealed space;
the ceramic diaphragm is configured to sense a first pressure of the medium on the lower surface;
the measuring element is configured to generate first resistance information when the lower surface of the ceramic diaphragm is subjected to the first pressure, and output the first resistance information to the processing element as a first electrical signal;
the processing element is configured to obtain absolute pressure information from the received first electrical signal.
Optionally, the ceramic substrate and the ceramic diaphragm are bonded by a colloid, and the accommodating space includes a hole formed above the colloid.
Optionally, the gel exposes the resistors of the wheatstone bridge and the compensation resistor, and the gel also exposes the through holes on the ceramic substrate.
Optionally, the wheatstone bridge is a half bridge circuit or a full bridge circuit.
The pressure sensor provided by the invention has at least one of the following advantages:
first, the pressure sensor of the present invention generates a resistance change by the ceramic diaphragm being deformed by pressure, and obtains a pressure value to be detected from the resistance change. Because the detection mode is based on the piezoresistive principle, the requirement on dielectric medium is not high, so the sealing requirement can be reduced, a circuit board can be omitted, and a processing element is directly installed on a ceramic substrate.
Secondly, the pressure sensor of the invention realizes the communication between the processing element and the measuring element directly through the conductive layers formed on the ceramic substrate and the ceramic diaphragm, and does not need to be separately wired, thereby further simplifying the circuit structure, improving the reliability of pressure measurement and further reducing the cost.
Drawings
The drawings are included to provide a better understanding of the invention and are not to be construed as unduly limiting the invention. Wherein:
FIG. 1 is an assembled structural view of a pressure sensor in an embodiment of the present invention;
FIG. 2 is an exploded structural view of a pressure sensor in an embodiment of the present invention;
FIG. 3 is a backside view of a ceramic substrate according to an embodiment of the present invention;
FIG. 4 is an enlarged view of a portion of the pressure sensor shown in FIG. 1 in area A;
fig. 5 is a schematic structural diagram of a colloid in an embodiment of the present invention.
In the figure:
10-a pressure sensor;
11-a ceramic matrix; 111-a via; 112-wire bond pads; 113-a groove;
12-a ceramic membrane; 13-a processing element; 14-a measuring element; 15-passive elements; 16-colloid; 161-breaking the hole; 162. 163-notch; 17-opening.
Detailed Description
The present invention will be described in more detail with reference to the accompanying drawings, in order to make the objects and features of the present invention more comprehensible, embodiments thereof will be described in detail below, but the present invention may be implemented in various forms and should not be construed as being limited to the embodiments described. As used in this specification, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the plural form "a plurality" is intended to include two or more. As used in this specification, the word "a" or "an" means an indefinite amount.
The core idea of the invention is to provide a pressure sensor, which is based on the piezoresistive principle to realize pressure measurement, thereby reducing the requirement of the sensor on dielectric medium, reducing the sealing requirement, thereby omitting a circuit board, and also installing a processing element to realize pressure detection, so that the circuit structure of the pressure sensor can be simplified, the reliability of the circuit structure can be improved, and the manufacturing cost can be reduced.
Specifically, the pressure sensor of the present invention includes a sensing module including a ceramic diaphragm and a measurement element, and a processing module including a ceramic substrate and a processing element. The measuring element is mounted on the upper surface of the ceramic diaphragm. The processing element is mounted on an upper surface of the ceramic base. The upper surface of the ceramic diaphragm is sealed with the lower surface of the ceramic substrate. And the processing element is in communication with the measurement element. In practical application, the ceramic diaphragm is used for sensing the pressure of a medium and generating deformation, in the deformation process, the measuring element generates corresponding resistance change and outputs the resistance change to the processing element in an electric signal mode, and then the processing element can obtain corresponding pressure information according to the received electric signal.
The "upper surface" and "lower surface" are not limitations on the orientation of the pressure sensor. It will also be appreciated that the processing element may be an integrated circuit having signal processing capabilities. The processing element may be an existing processing chip, and a person skilled in the art can know how to select the processing element based on the disclosure of the present application in combination with common knowledge in the art. And one or more processing chips can be set according to the measurement requirements. The packaging method of the processing element is not limited in the present invention, and the processing chip may be a chip packaged in a standard form such as SSOP or QFN, or may be integrated on a ceramic substrate in a bare chip form. In addition, in order to enhance the performance of the pressure sensor, the upper surface of the ceramic substrate is also provided with passive elements, wherein the passive elements are mainly peripheral circuit elements such as resistors, capacitors, magnetic beads, transient voltage suppression tubes and the like, and the passive elements can enhance the performance of the pressure sensor and ensure the reliability of pressure measurement. However, the present invention is not limited to specific number, specific type and layout of passive components, and the user can selectively set the passive components according to his/her own needs to meet the respective measurement requirements. In addition, the measuring element includes, but is not limited to, a wheatstone bridge, and may be other bridge circuits as long as the deformation of the ceramic diaphragm can be converted into a resistance change. In one embodiment, the measurement element is a Wheatstone bridge, which may be a half-bridge or a full-bridge circuit, and the Wheatstone bridge is secured to the ceramic wafer by means well known to those skilled in the art (including thick film printing processes and high temperature sintering curing processes).
The application scenario of the pressure sensor of the present invention is not limited, and the pressure sensor may be used in a vehicle or other devices requiring pressure measurement. For a clearer understanding of the present invention, the pressure sensor according to the present invention will be described in more detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 and 2 show an assembled structure and an exploded structure of a pressure sensor of the present embodiment, and in particular, the present embodiment provides a pressure sensor 10 including a sensing module and a processing module, wherein the processing module includes a ceramic substrate 11 and a processing element 13, and the sensing module includes a ceramic diaphragm 12 and a measuring element 14. The processing element 13 is mounted on the upper surface of the ceramic substrate 11, and the measuring element 14 is mounted on the upper surface of the ceramic diaphragm 12. The upper surface of the ceramic diaphragm 12 is sealed with the lower surface of the ceramic substrate 11 (i.e. ceramic sealing), and after sealing, the processing element 13 is in communication connection with the measuring element 14.
The specific measurement principle is as follows: the ceramic diaphragm 12 is deformed by sensing the pressure of the medium on the surface of the ceramic diaphragm 12, the measuring element 14 generates a corresponding resistance change by the deformation of the ceramic diaphragm 12, the measuring element 14 outputs the resistance change to the processing element 13 in an electric signal manner, and the processing element 13 processes the received electric signal to obtain corresponding pressure information. Here, the processing element 13 may obtain a pressure value, which may be an absolute pressure value or a differential pressure value, by digitizing the received electrical signal in a manner known to those skilled in the art. Wherein the electrical signal may be a voltage signal or a current signal, preferably a voltage signal.
In one embodiment, the lower surface of the ceramic diaphragm 12 senses a first pressure of a medium, and the upper surface of the ceramic diaphragm 12 may sense a second pressure of the medium, so that the measuring element 14 generates first resistance information when the lower surface of the ceramic diaphragm 12 receives the first pressure, and outputs the first resistance information to the processing element 13 as a first electrical signal, and the measuring element 14 generates second resistance information when the upper surface of the ceramic diaphragm 12 receives the second pressure, and outputs the second resistance information to the processing element 13 as a second electrical signal, and the processing element 13 acquires differential pressure information according to the received first electrical signal and the received second electrical signal.
In another embodiment, the upper surface of the ceramic diaphragm 12 is in a sealed environment, and the lower surface of the ceramic diaphragm 12 alone senses a first pressure of a medium, so that the measuring element 14 generates first resistance information when the lower surface of the ceramic diaphragm 12 receives the first pressure, and outputs the first resistance information to the processing element 13 as a first electrical signal, and the processing element 13 obtains absolute pressure information according to the received first electrical signal.
Therefore, the pressure sensor 10 of the present embodiment can realize measurement of a relative pressure or an absolute pressure. Compared with the prior art, the pressure sensor 10 of the present embodiment generates a resistance change in the measuring element 14 by the ceramic diaphragm 12 being deformed by pressure, and the processing element 13 can obtain a relative pressure value or an absolute pressure value to be detected according to the resistance change of the measuring element 14. Since the detection mode is based on the piezoresistive principle, the pressure sensor 10 of the present invention has low requirements for dielectrics, so that the sealing requirements can be reduced, thereby omitting a circuit board (such as a ceramic circuit board, a flexible circuit board or a PCB board, etc.), and directly mounting the processing element 13 on the ceramic substrate 11. By doing so, pressure detection's circuit structure is simpler, and pressure measurement's reliability is also higher, and pressure detection is with low costs moreover, and two surfaces of the ceramic diaphragm of also being convenient for simultaneously all can experience medium pressure to can realize relative pressure or absolute pressure's measurement, thereby improve pressure measurement's flexibility, the various measurement demands of better satisfying from this. The thickness of the ceramic diaphragm 12 is not limited in the present invention, and is selected according to the range of the pressure sensor, and generally the larger the range, the larger the thickness is selected, for example, the thickness of the ceramic diaphragm 12 may be 0.2mm, 0.25mm, 0.38mm, or 0.5 mm.
Further, the pressure sensor 10 further includes a conductive circuit, and the processing element 13 is in communication with the outside and in communication with the measuring element 14 through the conductive circuit, and also electrically connected to the passive element. Furthermore, the conductive circuit comprises a first conductive layer, a second conductive layer and a third conductive layer, and the first conductive layer, the third conductive layer and the second conductive layer are electrically connected in sequence. Wherein the first conductive layer is integrated with the ceramic substrate 11 and electrically connected to the processing element 13, for example, a conductive line is printed on the upper surface of the ceramic substrate or a conductive line is printed inside the ceramic substrate, so that the ceramic substrate forms a multilayer ceramic structure; the second conductive layer is directly formed on the upper surface of the ceramic diaphragm 12 and is electrically connected to the measuring element 14; the third conductive layer is formed directly inside the ceramic base 11. Thus, the electrical connection between the processing element 13 and the measuring element 14 can be realized quickly and simply by the first conductive layer, the second conductive layer, and the third conductive layer, and in doing so, separate routing and wiring are not required, so that the circuit structure can be simplified, and the reliability of the circuit structure can be improved and the cost can be further reduced.
The first conductive layer specifically includes a plurality of conductive lines, and the specific number of the conductive lines is not limited. The plurality of leads of the first conductive layer may be printed on the upper surface of the ceramic substrate 11 or inside the ceramic substrate by a thick film printing process, or may be printed on the upper surface of the ceramic substrate 11 or inside the ceramic substrate by a high temperature co-firing ceramic process, or may be printed on the upper surface of the ceramic substrate 11 or inside the ceramic substrate by a low temperature co-firing ceramic process. That is, the wires of the first conductive layer may be prepared on the upper surface or inside of the ceramic substrate 11 by a manufacturing process known to those skilled in the art.
The ceramic substrate 11 preferably has a through hole 111 (or a via hole), the through hole 111 penetrates through the upper surface and the lower surface of the ceramic substrate 11, and a third conductive layer is disposed in the through hole 111. The number of the through holes 111 corresponds to the number of the output terminals of the measuring element 14, for example, when the measuring element 14 is a wheatstone bridge, four arms of the wheatstone bridge form four output terminals, and each output terminal is electrically connected to the third conductive layer through the second conductive layer. In this embodiment, the number of the through holes 111 is four, and one third conductive layer is disposed in each through hole 111, so that each output end is electrically connected to a corresponding third conductive layer through the second conductive layer. Further, the third conductive layer is a conductive material, the conductive material is filled in the through hole 111, and the conductive material may be copper or gold, and the conductive material is not limited in the present invention. In the alternative, the third conductive layer may be a wire (i.e., a wire) directly fixed within the through hole 111.
The second conductive layer also includes a plurality of conductive lines, and the specific number of conductive lines is not limited. The plurality of conducting wires of the second conducting layer can be printed on the upper surface of the ceramic diaphragm 12 through a thick film printing process, and then the conducting wires are sintered and solidified at high temperature to be solidified on the upper surface of the ceramic diaphragm 12. In this embodiment, the measuring element 14 is a wheatstone bridge, and accordingly, the second conductive layer includes a plurality of bridge leads, and more preferably, the second conductive layer further includes a plurality of bridge pads, two ends (i.e., two output ends) of each bridge arm of the wheatstone bridge are connected to one of the bridge leads, and each of the bridge leads is electrically connected to a corresponding one of the bridge pads. Similarly, the bridge leads are sequentially formed on the upper surface of the ceramic diaphragm 12 by a thick film printing process and a high-temperature sintering and curing process. Each bridge pad is electrically connected with a corresponding third conductive layer, so that the signal output by the measuring element 14 is transmitted to the processing element 13 through the conductive material or the conducting wire in the through hole, and the circuit structure is simple and the assembly is convenient.
With continued reference to fig. 1, the conductive circuit further includes a fourth conductive layer directly formed on the upper surface of the ceramic substrate 11, and the processing element 13 is configured to communicate with the outside, for example, to connect to an external output port through the fourth conductive layer. Preferably, the fourth conductive layer includes a plurality of lead pads 112, and the number of the lead pads 112 is optionally three, one of the lead pads is used for grounding, one of the lead pads is used for connecting with a power supply, and the other lead pad is used for signal transmission. More specifically, the signal processed by the processing element 13 is transmitted to the lead pad 112 through the wires of the first conductive layer. The shape of the bridge pad and/or the wire pad is not limited, and includes, but is not limited to, a circular shape. In addition, in an alternative embodiment, the fourth conductive layer may also be replaced by a pin, and the communication between the pressure sensor and the outside is realized through the pin.
In order to improve the accuracy of the pressure measurement, the sensing module further comprises a compensation circuit, which is arranged on the ceramic diaphragm 12, preferably on the upper surface of the ceramic diaphragm 12, or on the ceramic substrate 11. The compensation circuit is used to bias the output of the measurement element 14 below a predetermined value when the ceramic diaphragm 11 is not under load (i.e. zero pressure). Further, the compensation circuit includes at least one compensation resistor R, as shown in fig. 2, wherein at least one compensation resistor R is connected in parallel or in series on at least one arm end of the wheatstone bridge, so that the output voltage of the wheatstone bridge is zero at zero pressure, and the wheatstone bridge is in a balanced state. The compensation resistor R may be printed on the upper surface of the ceramic diaphragm 12, or may be printed on the upper surface of the ceramic substrate 11. Preferably, the surface of the compensation resistor and the bridge resistor is covered with a protective layer, so that the wheatstone bridge and the compensation resistor can be protected from the influence of the measuring medium, and the reliability of the measurement can be ensured. The protective layer can be glass glaze and is coated on the surfaces of the compensation resistor and the bridge resistor. As mentioned above, the compensation resistor R can also be fixed by a thick film printing process and a high temperature sintering curing process.
The treatment module further comprises passive components 15 mounted on the upper surface of the ceramic substrate 11 and distributed around the treatment components 13. The passive element 15 is mainly a resistor, a capacitor, a magnetic bead, a transient voltage suppression tube and other peripheral circuit elements, and the arrangement of the passive element can enhance the performance of the pressure sensor and ensure the reliability of pressure measurement.
Continuing to refer to fig. 2, in actual assembly, the ceramic substrate 11 and the ceramic diaphragm 12 are ceramic sealed together, and at least the measuring element 14 is located between the ceramic substrate 11 and the ceramic diaphragm 12, and an accommodating space is formed between the ceramic diaphragm 12 and the ceramic substrate 11, so that the measuring element 14 is directly located in the accommodating space, thereby reserving a space for strain. Preferably, the accommodating space is arranged in the middle, and more preferably, the accommodating space is further used for limiting the displacement of the deformation of the ceramic diaphragm 12 towards the ceramic substrate 11, so that the effectiveness of the ceramic diaphragm 12 is ensured, and the failure caused by overlarge deformation is avoided.
Specifically, the ceramic substrate 11 and the ceramic diaphragm 12 are bonded together by a colloid 16, and the more specific implementation manner is as follows: for example, glass paste is printed on the upper surface of the ceramic diaphragm 12 or the lower surface of the ceramic substrate 11 by a thick film printing process, and after printing, the ceramic diaphragm 12 and the ceramic substrate 11 are sintered and cured together by a high temperature sintering and curing process. Preferably, when the glass paste is printed, the bridge resistor, the compensation resistor and the through hole are avoided, so that the bridge resistor, the compensation resistor and the through hole are not covered by the glass paste. As shown in fig. 2, the glass paste is solidified to form a gel 16, a break hole 161 is formed in the gel 16, the break hole 161 is centrally disposed to avoid a wheatstone bridge, and a notch 162 to avoid the compensation resistor R and a notch 163 to avoid the through hole 111 are formed around the break hole 161. The shapes of the hole 161 and the notches 162 and 163 are not limited, but are preferably the same as the shape of the element to be avoided. So that the bridge wire pad is electrically connected to the third conductive layer in the via hole 111 through the gap 163. It should be understood that the hole 161 is a part of the accommodating space.
Referring to fig. 3, a groove 113 is formed on the lower surface of the ceramic substrate 11, and the groove 113 is a blind hole, and the depth of the blind hole limits the displacement of the deformation of the ceramic diaphragm 12. That is, the depth of the groove 113 is determined according to the span of the pressure sensor, and optionally, the depth of the groove 113 is not more than 0.5 mm. Optionally, the shape of the groove 113 is circular, and the diameter is between 3.0mm and 10.0mm, for example, the diameter may be 3.0mm, 4.0mm, 8.0mm or 10.0 mm. Furthermore, the groove 113 and the broken hole 161 may be axially aligned, that is, the groove 113, the colloid 16, the ceramic diaphragm 12 and the ceramic substrate 11 jointly define the accommodating space.
As mentioned above, the pressure sensor 10 of the present embodiment can realize the measurement of the relative pressure, in this case, as shown in fig. 1, fig. 2 and fig. 4, an incompletely sealed ceramic sealing structure is formed between the ceramic substrate 11 and the ceramic diaphragm 12, that is, the accommodating space has an opening 17 communicated with the atmosphere, so that the internal pressure of the accommodating space is the same as the ambient pressure, and this way, the pressure sensor 10 can directly measure the relative pressure. Specifically, the upper surface of the ceramic diaphragm 12 can sense the second pressure of the medium through the opening 17, and the lower surface of the ceramic diaphragm 12 can sense the first pressure of the medium. In this embodiment, the opening 17 communicating with the hole 161 is directly formed on the solidified glue 16, so that the accommodating space communicates with the external atmosphere, and the cross section of the hole 161 is an unclosed surface. Further, the opening 17 may be one or more, and the shape of the opening is not limited.
In other embodiments, the pressure sensor 10 can measure absolute pressure, and in this case, as shown in fig. 5, a completely sealed ceramic sealing structure is formed between the ceramic substrate 11 and the ceramic diaphragm 12, that is, no opening is formed on the cured gel 16, and the cross section of the broken hole 161 is a closed surface, so that the accommodating space is completely sealed and is in vacuum (complete vacuum or partial vacuum is available), so that the upper surface of the ceramic diaphragm 12 is in a sealed environment, and the first pressure of the medium is sensed through the lower surface.
In summary, the above embodiments have described the sealing method of the pressure sensor and the implementation method of the conductive circuit in detail, but it is understood that the present invention is not limited to the embodiments described above, and any changes based on the embodiments provided above are within the scope of the present invention. One skilled in the art can take the contents of the above embodiments to take a counter-measure.
It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (15)
1. A pressure sensor comprising a sensing module comprising a ceramic diaphragm and a measuring element, and a processing module comprising a ceramic substrate and a processing element;
the measuring element is arranged on the upper surface of the ceramic diaphragm, the processing element is arranged on the upper surface of the ceramic substrate, the upper surface of the ceramic diaphragm is sealed with the lower surface of the ceramic substrate, and the processing element is in communication connection with the measuring element; wherein: the measuring element is configured to generate corresponding resistance change when the ceramic diaphragm is deformed under the stress, and the resistance change is output to the processing element in an electric signal mode; the processing element is configured to obtain corresponding pressure information from the received electrical signal.
2. The pressure sensor of claim 1, further comprising conductive traces including a first conductive layer, a second conductive layer, and a third conductive layer, the first conductive layer, the third conductive layer, and the second conductive layer being electrically connected in sequence;
the first conducting layer is integrated with the ceramic substrate and is electrically connected with the processing element; the second conducting layer is directly formed on the upper surface of the ceramic diaphragm and is electrically connected with the measuring element; the third conductive layer is formed directly inside the ceramic base.
3. The pressure sensor according to claim 2, wherein the ceramic base has a through hole penetrating through upper and lower surfaces of the ceramic base, and the third conductive layer is disposed in the through hole.
4. The pressure sensor of claim 3, wherein the third conductive layer is a conductive material, the conductive material filling the through hole; alternatively, the first and second electrodes may be,
the third conducting layer is a conducting wire which is fixed in the through hole.
5. The pressure sensor of claim 4, wherein the measuring element is a Wheatstone bridge, the second conductive layer comprises a plurality of bridge leads and a plurality of bridge pads, one bridge lead is connected to each end of each bridge arm of the Wheatstone bridge, and each bridge lead is electrically connected to a corresponding one of the bridge pads;
the number of the through holes is consistent with that of the bridge pads, one third conducting layer is arranged in each through hole, and each bridge pad is electrically connected to one corresponding third conducting layer.
6. The pressure sensor of claim 1, further comprising an electrically conductive trace, the electrically conductive trace comprising a fourth electrically conductive layer; the fourth conducting layer is directly formed on the upper surface of the ceramic substrate and is electrically connected with the processing element; the processing element is in communication connection with the outside through the fourth conductive layer.
7. The pressure sensor of claim 6, wherein the fourth conductive layer includes a plurality of wire bond pads, each of the wire bond pads being electrically connected to the processing element by a wire.
8. The pressure sensor of claim 1, wherein the sensing module further comprises a compensation circuit disposed on the ceramic diaphragm or the ceramic substrate for biasing an output of the measurement element below a predetermined value when the ceramic diaphragm is not under force.
9. A pressure sensor as claimed in claim 8, characterized in that the measuring element is a Wheatstone bridge and the compensating circuit comprises at least one compensating resistor, at least one of which is connected in parallel or in series at least one leg end of the Wheatstone bridge.
10. The pressure sensor of claim 1, wherein the processing module further comprises a passive component disposed on an upper surface of the ceramic substrate.
11. The pressure sensor of claim 1, wherein the processing element comprises at least one processing chip, the processing chip being a package structure or a die.
12. The pressure sensor of claim 1, wherein a receiving space is formed between the ceramic substrate and the ceramic diaphragm, the receiving space is centrally disposed, and the measuring element is located in the receiving space.
13. The pressure sensor of claim 12, wherein the receiving space has at least one opening;
the ceramic diaphragm is configured such that a lower surface senses a first pressure of the medium and an upper surface senses a second pressure of the medium through the opening;
the measuring element is further configured to generate first resistance information when the lower surface of the ceramic diaphragm is subjected to the first pressure, and output the first resistance information to the processing element as a first electrical signal; the measuring element is further configured to generate second resistance information when the upper surface of the ceramic diaphragm is subjected to the second pressure, and output the second resistance information to the processing element as a second electrical signal;
the processing element is configured to obtain differential pressure information from the received first and second electrical signals.
14. The pressure sensor of claim 12, wherein the receiving space is a sealed space, and a part of the upper surface of the ceramic diaphragm is sealed with the ceramic substrate, and another part of the upper surface is located in the sealed space;
the ceramic diaphragm is configured to sense a first pressure of a medium on the lower surface;
the measuring element is configured to generate first resistance information when the lower surface of the ceramic diaphragm is subjected to the first pressure, and output the first resistance information to the processing element as a first electrical signal;
the processing element is configured to obtain absolute pressure information from the received first electrical signal.
15. The pressure sensor of claim 12, wherein the ceramic substrate and the ceramic diaphragm are bonded by a gel, and the receiving space includes a hole formed on the gel.
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| CN202010292154.8A CN113532704A (en) | 2020-04-14 | 2020-04-14 | Pressure sensor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010292154.8A CN113532704A (en) | 2020-04-14 | 2020-04-14 | Pressure sensor |
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| CN113532704A true CN113532704A (en) | 2021-10-22 |
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| CN114112122A (en) * | 2021-11-30 | 2022-03-01 | 无锡胜脉电子有限公司 | High-precision ceramic pressure sensor |
| CN114739544A (en) * | 2022-02-23 | 2022-07-12 | 万津实业(赤壁)有限公司 | Pressure monitoring diaphragm, assembly and pressure monitoring method |
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