CN113816329B - Resonance pressure sensitive chip probe of vacuum packaging structure and packaging method thereof - Google Patents
Resonance pressure sensitive chip probe of vacuum packaging structure and packaging method thereof Download PDFInfo
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- CN113816329B CN113816329B CN202110984929.2A CN202110984929A CN113816329B CN 113816329 B CN113816329 B CN 113816329B CN 202110984929 A CN202110984929 A CN 202110984929A CN 113816329 B CN113816329 B CN 113816329B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/0032—Packages or encapsulation
- B81B7/0035—Packages or encapsulation for maintaining a controlled atmosphere inside of the chamber containing the MEMS
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00261—Processes for packaging MEMS devices
- B81C1/00277—Processes for packaging MEMS devices for maintaining a controlled atmosphere inside of the cavity containing the MEMS
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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
- G01L1/10—Measuring force or stress, in general by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0264—Pressure sensors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
A resonance pressure sensitive chip probe of a vacuum packaging structure and a packaging method thereof relate to a probe and a packaging method thereof. The invention aims to solve the problems of low Q value, reduced measurement accuracy and reduced long-term stability of the existing resonance pressure sensitive chip. The kovar alloy pins are arranged on the lead holes, the silicon resonance pressure sensitive chip is arranged on the chip bonding surface, a gap is reserved between the silicon resonance pressure sensitive chip and the side wall of the step groove, and the silicon resonance pressure sensitive chip is connected with the kovar alloy pins through electrode bonding leads; the sealing cover plate is arranged on the contact surface of the sealing cover plate, and a closed cavity for protecting the resonance pressure sensitive chip is formed between the probe medium transmission channel and the three-stage stepped groove of the sealing tube seat. The packaging method comprises the following steps: and (3) carrying out secondary packaging on the resonant layer to enable the silicon resonant pressure sensitive chip to work in a vacuum medium. The invention is used for measuring pressure and packaging the pressure chip probe.
Description
Technical Field
The invention relates to a resonance pressure sensitive chip probe and a packaging method thereof, in particular to a resonance pressure sensitive chip probe of a vacuum packaging structure and a packaging method thereof, belonging to the field of MEMS resonance type pressure sensors.
Background
The silicon resonance pressure sensor indirectly measures pressure by measuring the change of the natural frequency of silicon, the accuracy is 1-2 orders of magnitude higher than that of a general pressure sensor, the operation is reliable, and the stability and the repeatability are good; the core part of the silicon resonant pressure sensor is a resonator, the Q value is a core index for evaluating the resonator, and the larger the Q value is, the better the performance of the resonator is. The resonant layer of the silicon resonant pressure sensor needs to be in a low pressure environment to maintain operation at a normal Q value, and the pressure of the working environment of the sealed cavity is inversely proportional to the Q value. The stable vacuum environment can ensure that the resonator works with a fixed Q value, thereby ensuring that the silicon resonant pressure sensor has high stability.
Leak rate is an important parameter for the stability performance of the resonant pressure sensor chip. The most common pressure absolute measurement die seal is made by silicon-silicon bonding, silicon glass bonding, and other crystalline material bonding. The existing packaging method generally adopts the absolute pressure cavity to be exposed in the atmospheric pressure range, so that the leak rate of the sealing cavity of the high-precision absolute pressure sensor is increased, the pressure in the vacuum cavity is increased, the signal output value of the sensor chip is directly influenced, and the problems of reduced measurement precision and long-term stability of the sensor chip are caused.
In summary, the existing resonant pressure sensitive chip has the problems of low Q value, and influence on the measurement accuracy and application range thereof, and the existing packaging method has the problems of reduced measurement accuracy and long-term stability.
Disclosure of Invention
The invention aims to solve the problems that the existing resonant pressure sensitive chip has low Q value and affects the measurement accuracy and the application range, and the existing packaging method has the problems of reduced measurement accuracy and long-term stability. And further provides a resonance pressure sensitive chip probe of a vacuum packaging structure and a packaging method thereof.
The technical scheme of the invention is as follows: the resonance pressure sensitive chip probe of the vacuum packaging structure comprises a sealing cover plate, a silicon resonance pressure sensitive chip, kovar alloy pins, electrode bonding leads, a probe medium transmission channel and a sealing tube seat; the upper end face of the sealing tube seat is a sealing cover plate contact face, a three-level stepped groove is formed in the sealing cover plate contact face, a middle stepped face of the stepped groove is a lead hole face, a lower stepped face is a chip bonding face, a probe medium transmission channel is formed in the chip bonding face, a plurality of lead holes are vertically formed in the lead hole face, an annular sealing groove is formed in the middle of the outer cylindrical face of the sealing tube seat, and a pressure buffer groove is formed in the lower portion of the outer cylindrical face of the sealing tube seat; the kovar alloy pins are vertically arranged on lead holes of the sealing tube seat in a glass sintering mode, the silicon resonance pressure sensitive chip is arranged on a chip bonding surface of the sealing tube seat in an adhesive mode, a gap is reserved between the silicon resonance pressure sensitive chip and the side wall of the stepped groove, and the silicon resonance pressure sensitive chip is connected with the kovar alloy pins through electrode bonding leads; the sealing cover plate is arranged on the contact surface of the sealing cover plate, and a closed cavity for protecting the silicon resonance pressure sensitive chip is formed between the probe medium transmission channel and the three-stage stepped groove of the sealing tube seat.
The invention also provides a packaging method, which comprises the following steps:
step one: manufacturing and cleaning a sealing tube seat;
the glass slurry sinters the lead hole and the upper and lower pins in the sealing tube seat together to form a sealing pin structure, and the sealing tube seat is made of stainless steel;
respectively clamping a silk fabric cleaning sealing tube seat adhered with acetone and absolute ethyl alcohol by using stainless steel tweezers with the heads coated with polytetrafluoroethylene, cleaning the sealing tube seat for more than 20s by using absolute ethyl alcohol, and drying in a drying oven; placing the silicon resonance pressure sensitive chip into acetone and absolute ethyl alcohol in sequence, respectively carrying out ultrasonic cleaning on the sealing tube seat and the silicon resonance pressure sensitive chip for 15min, and placing the special fixture ceramic ring into acetone and absolute ethyl alcohol in sequence for ultrasonic cleaning for 15+/-3 min;
step two: gluing and bonding;
fixing a sealing tube seat on a fixture, picking 730 glue by using a toothpick or using an automatic glue dispenser to uniformly point 6 points on the sealing tube seat according to the appearance of a silicon resonance pressure sensitive chip, embedding the silicon resonance pressure sensitive chip in the sealing tube seat, tightly pressing the upper part of a chip upper cover of the silicon resonance pressure sensitive chip by using a ceramic rod to ensure that an external pressure hole on the sealing tube seat corresponds to a pressure sensing through hole of a stress isolation layer, continuously picking 730 glue by using the toothpick or using an automatic glue dispenser to carry out glue dispensing, protecting a kovar alloy pin corresponding to a through hole of a ceramic ring of a special fixture, and taking out the ceramic ring after the glue is coated;
step three: curing the glue;
placing the sealing tube seat bonded with the silicon resonance pressure sensitive chip in the second step in a constant temperature and humidity environment for curing for 20-30 hours;
step four: bonding electrode bonding wires;
step four, first: fixing the sealing tube seat on a fixture, and welding the electrode bonding lead and the extraction electrode together at a position where the diameter of the electrode bonding lead on the surface of the extraction electrode is 2.5 times as large as that of the tip of the chopper;
step four, two: welding the other end of the electrode bonding wire on the kovar alloy pin through a hot welding pen, wherein the length of the electrode bonding wire is automatically formed when two points are pressed and welded;
and step four, three: carrying out a breaking force test on the electrode bonding lead 4 until the breaking force meets the design requirement;
step five: performing insulation test on the Kovar alloy pin 3 and the sealing tube seat 6;
an insulation resistance tester is adopted to test insulation resistance between each pin of the kovar alloy pins 3 and the sealing tube seat 6, and the resistance is larger than a design limit value;
step six: testing the basic performance of the silicon resonance pressure sensitive chip;
the water absorbing ball is adopted to blow the pressure guiding hole, the pressure change is less than hundreds of hertz, and meanwhile, the temperature frequency is not changed; at this time, the silicon resonance pressure sensitive chip meets the design requirement;
step seven: welding the sealing cover plate on the sealing tube seat;
placing the sealing cover plate on a sealing tube seat, welding by using argon arc or electron beam, and then performing penetration test; repeating the fifth step;
step eight: plugging the sealing tube seat;
firstly sealing a vacuum-pumping hole with the diameter of 1.3mm by using a phi 2 steel ball, and then sealing and welding the vacuum-pumping closed cavity by using electron beam welding;
thus, the encapsulation of the resonance pressure sensitive chip probe of the vacuum encapsulation structure is completed;
step nine: electrically testing the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
performing electrical test under constant normal pressure, and stabilizing the resonance pressure sensitive chip probe to be qualified in less than 3 seconds when the resonance pressure sensitive chip probe does not generate frequency hopping phenomenon and the frequency changes towards one direction;
step ten: performing pressure fatigue and aging tests on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
the resonance pressure sensitive chip probe is arranged on the clamp and is connected with the pneumatic fatigue machine or the hydraulic fatigue machine, the fatigue times are 5000/10000, and the temperature aging experiment is carried out in a high-low temperature test box, so that the internal stress of the resonance pressure sensitive chip probe is released together, and the output stability of the resonance pressure sensitive chip of the vacuum packaging structure is improved;
step eleven: performing air tightness detection on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
connecting the resonance pressure sensitive chip probe with a pressure controller for air tightness detection, wherein the pressure change value is not more than +/-2 Pa, and the air tightness of the resonance pressure sensitive chip probe is qualified at the moment;
step twelve: and (3) performing laser marking and screening on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging, and transferring to the next production stage.
Compared with the prior art, the invention has the following effects:
1. the method for carrying out secondary vacuum packaging on the resonant chip can reduce the working environment pressure of the sealed cavity, thereby reducing the pressure difference between the sealed cavity and the external environment, and realizing the reduction of the integral leakage rate of the chip under the condition that the leakage rate of the sealed cavity of the chip is the same, thereby reducing the pressure change in the cavity of the sealed cavity caused by the leakage rate and improving the stability of the sensor.
2. The external pressure value of the chip sealing cavity of the silicon resonance pressure sensitive probe prepared by the invention is 100Pa-1000Pa, and the chip sealing cavity in the traditional packaging mode is directly exposed to the atmospheric pressure environment, and is usually about 100000 Pa. Because the leak rate of the seal cavity is in direct proportion to the pressure difference between the seal cavity and the outside, the pressure of the seal cavity after bonding is generally below 100 Pa. Therefore, the chip leakage rate can be reduced by two orders of magnitude under the condition of the same chip bonding process by adopting a secondary vacuum packaging method.
3. The vacuum packaging structure can isolate the silicon resonance pressure sensitive chip 2 from the external atmospheric environment in a sealing way, and the secondary packaging method of the resonance chip can reduce the working environment pressure of the sealing cavity, thereby reducing the pressure difference between the sealing cavity and the external environment, reducing the pressure change in the cavity caused by leakage rate of the sealing cavity, and improving the stability of the sensor.
Drawings
FIG. 1 is a full cross-sectional view of a silicon resonant pressure sensitive chip probe of the vacuum package structure of the present invention;
FIG. 2 is a front cross-sectional view of a silicon resonant pressure sensitive chip;
FIG. 3 is a front cross-sectional view of the seal cover plate;
FIG. 4 is a top view of the seal cover plate;
FIG. 5 is a front cross-sectional view of a kovar pin;
FIG. 6 is a front cross-sectional view of a seal tube holder;
fig. 7 is a top view of a resonant layer.
Detailed Description
The technical scheme of the invention is not limited to the specific embodiments listed below, and also comprises any reasonable combination of the specific embodiments.
The first embodiment is as follows: referring to fig. 1 to 7, a resonant pressure sensitive chip probe of a vacuum package structure according to the present embodiment includes a sealing cover plate 1, a silicon resonant pressure sensitive chip 2, kovar pins 3, electrode bonding wires 4, a probe medium transfer passage 5, and a sealing socket 6; the upper end face of the sealing tube seat 6 is a sealing cover plate contact face 601, a three-level stepped groove is formed in the sealing cover plate contact face 601, a middle stepped face of the stepped groove is a lead hole face 604, a lower stepped face of the stepped groove is a chip bonding face 602, a probe medium transmission channel 5 is formed in the chip bonding face 602, a plurality of lead holes 603 are vertically formed in the lead hole face 604, an annular sealing groove 605 is formed in the middle of the outer cylindrical face of the sealing tube seat 6, and a pressure buffer groove 606 is formed in the lower portion of the outer cylindrical face of the sealing tube seat 6;
the kovar alloy pins 3 are vertically arranged on the lead holes 603 of the sealing tube seat 6 in a glass sintering mode, the silicon resonance pressure sensitive chip 2 is arranged on the chip bonding surface 602 of the sealing tube seat 6 in an adhesive mode, a gap is reserved between the silicon resonance pressure sensitive chip 2 and the side wall of the stepped groove, and the silicon resonance pressure sensitive chip 2 and the kovar alloy pins 3 are connected through electrode bonding leads 4; the sealing cover plate 1 is arranged on the contact surface 601 of the sealing cover plate, and a closed cavity for protecting the silicon resonance pressure sensitive chip 2 is formed between the probe medium transmission channel 5 and the three-stage stepped groove of the sealing tube seat 6.
The second embodiment is as follows: referring to fig. 2, the silicon resonant pressure sensitive chip 2 of the present embodiment includes a chip upper cover 201, a resonant layer 202, a silicon substrate 2021, and a stress isolation layer 203, where the chip upper cover 201, the resonant layer 202, the silicon substrate 2021, and the stress isolation layer 203 are sequentially connected from top to bottom and made into a whole, and an inverted trapezoidal pressure sensing groove is formed on a lower end surface of the silicon substrate 2021, where an insulating chamber is formed between the chip upper cover 201 and the silicon substrate 2021, and the resonant layer 202 is located in the insulating chamber. The arrangement is that the inverted trapezoid pressure sensing groove on the lower end face of the silicon substrate 2021 is convenient for accurately sensing the medium pressure and transmitting the medium pressure to the resonant layer 202, and meanwhile, an absolute pressure chamber formed between the silicon substrate 2021 and the silicon substrate 2021 is used for protecting the resonant layer 202, so that resistance of other mediums received when the resonant layer 202 is in a working state is avoided, and further the measuring accuracy of the probe is affected. Other components and connection relationships are the same as those of the first embodiment.
And a third specific embodiment: the present embodiment will be described with reference to fig. 2, in which a pressure-sensitive through-hole 2031 is formed in the middle of the stress isolation layer 203. The arrangement is convenient for transmitting pressure to the silicon substrate 2021 and then to the resonance layer 202, so as to achieve the purpose of pressure sensing. Other components and connection relationships are the same as those of the first or second embodiment.
The specific embodiment IV is as follows: the resonant layer 202 of this embodiment includes four lead-out electrodes 3050, two driving electrodes 3023, a back-up electrode 3024, two sensitive comb electrodes 3025, two stabilizing beams 3026, two cross-tie beams 3027, anchor blocks 3028 and electrode passages 3029,
the two driving electrodes 3023 are arranged in parallel up and down, the left side and the right side of each driving electrode 3023 are respectively provided with one extraction electrode 3050, the opposite sides of the two driving electrodes 3023 are respectively provided with one sensitive comb electrode 3025, the inner sides of the two sensitive comb electrodes 3025 are respectively provided with one stable beam 3026, the inner sides of the two stable beams 3026 are respectively provided with one transverse beam 3027, an anchor block 3028 is arranged between the two transverse beams 3027, and the anchor block 3028 is connected with the standby electrode 3024 through an electrode passage 3029. So set up, electrode passageway 3029 constitutes triangle-shaped stable structure, under the prerequisite of guaranteeing signal transmission, promotes the intensity that the electrode was admittedly propped up, can effectively promote the stability of resonance layer to be applicable to the deformation range that higher frequency vibration and pressure change arouse. Meanwhile, the anchor block 3028 is arranged, the side length of the force arm is increased, the torque generated by stress of the anchor block 3028 can be effectively improved, and the deformation of the rear end connected with the related stress beam is improved. Thereby improving the resonant frequency and increasing the resolution of the sensor. Other compositions and connection relationships are the same as any one of the first to third embodiments.
Fifth embodiment: the present embodiment will be described with reference to fig. 7, in which each of the tie beams 3027 has a Y-beam structure at its end. The Y-shaped beam structure with double fixed fulcrums is arranged in the way, so that a triangular stable structure is formed, the rigidity strength can be improved, and the reliability of the sensor is improved. Other compositions and connection relationships are the same as those in any one of the first to fourth embodiments.
Specific embodiment six: describing the present embodiment in conjunction with fig. 7, each stabilizing beam 3026 of the present embodiment includes two stabilizing units that are symmetrical left and right,
each stabilizing unit comprises a first connecting support beam 901, a first cable-stayed beam parallel support beam 901-1, a first cable-stayed beam vertical support beam 901-2, a first parallel support beam vertical beam 901-3, a first cable-stayed beam stabilizing beam 901-4 and a second cable-stayed beam stabilizing beam 901-5,
a trapezoid structure is formed among the first cable-stayed beam parallel support beam 901-1, the first cable-stayed beam stabilizing beam 901-4, the second cable-stayed beam stabilizing beam 901-5 and the sensitive comb electrode 3025, the first cable-stayed beam vertical support beam 901-2 and the first parallel support beam vertical beam 901-3 are vertical to the first cable-stayed beam parallel support beam 901-1, right triangles are formed between the first cable-stayed beam vertical support beam 901-2 and the first parallel support beam vertical beam 901-3 and the first cable-stayed beam stabilizing beam 901-4 and the second cable-stayed beam stabilizing beam 901-5 as well as between the first cable-stayed beam parallel support beam 901-1,
one end of the first connecting support beam 901 coincides with the intersection point of the first cable-stayed beam vertical support beam 901-2 and the first cable-stayed beam parallel support beam 901-1, and the other end of the first connecting support beam 901 coincides with the intersection point of the first parallel support beam vertical beam 901-3 and the second cable-stayed beam stabilizing beam 901-5. So set up, can form triangle bearing structure, the oblique pulling force of each supporting beam of increase syntonizing layer and sensitive broach electrode 3025 to increase mechanical vibration transmission intensity, improve chip vibration frequency, and then can effectively increase the measurement range, and reduced external disturbance, thereby promote stability. Other compositions and connection relationships are the same as those in any one of the first to fifth embodiments.
Seventh embodiment: the probe medium transfer passage 5 of the present embodiment includes a pilot hole 501, an external pressure hole 502 and an internal pressure line 503,
the pressure guiding hole 501 is arranged on the die bonding surface 602 and is communicated with the silicon substrate 2021, the external pressure hole 502 is arranged on the annular sealing groove 605, and the pressure guiding hole 501 and the external pressure hole 502 are connected through an internal pressure pipeline 503.
So set up, the external pressure hole 502 of probe medium transfer passageway 5 can be with by external measured pressure after the internal pressure pipeline 503 transmits to leading pressure hole 501, get into the pressure sensing face of silicon resonance pressure sensitive chip 2, and silicon resonance pressure sensitive chip 2 keeps apart with outside atmospheric environment simultaneously, maintains vacuum packaging state. Other compositions and connection relationships are the same as those in any one of the first to sixth embodiments.
Eighth embodiment: referring to fig. 3 and 4, the sealing cover plate 1 of the present embodiment includes a T-shaped table 101, a vacuumizing hole 102, a circular boss 103 and a notch 104, the circular boss 103 is embedded in a groove on an upper end surface of the T-shaped table 101, the vacuumizing hole 102 is formed in the vertical direction of the T-shaped table 101, and four notches 104 are uniformly formed in the circular boss 103.
The sealing cover plate 1 is arranged at the top of the vacuum packaging structure, and is generally made of weldable metal materials, the external dimension of the sealing cover plate 1 and the dimension of the upper end of the contact surface of the sealing tube seat 6 are required to be matched, and meanwhile, the sealing cover plate 1 and the sealing tube seat 6 are made of weldable materials. The front surface of the sealing cover plate 1 is provided with a vacuumizing hole 102, vacuumizing is carried out through the vacuumizing hole 102, and after the vacuumizing hole 102 is welded after the vacuumizing degree requirement is met, the internal vacuum degree of the vacuum packaging structure is ensured. Other compositions and connection relationships are the same as those in any one of the first to seventh embodiments.
Detailed description nine: the packaging method of the present embodiment will be described with reference to fig. 1 to 7, and includes the steps of:
step one: manufacturing and cleaning a sealing tube seat 6;
the glass slurry sinters the lead hole 603 and the upper and lower pins in the sealing tube seat 6 together to form a sealing pin structure, and the sealing tube seat 6 is made of stainless steel;
respectively clamping a silk cleaning sealing tube seat 6 adhered with acetone and absolute ethyl alcohol by using stainless steel tweezers with the heads coated with polytetrafluoroethylene, cleaning the silk cleaning sealing tube seat by using absolute ethyl alcohol for more than 20s, and drying the silk cleaning sealing tube seat in a drying oven; placing the silicon resonance pressure sensitive chip 2 into acetone and absolute ethyl alcohol in sequence, respectively carrying out ultrasonic cleaning on the sealing tube seat 6 and the silicon resonance pressure sensitive chip 2 for 15min, and placing the special fixture ceramic ring into acetone and absolute ethyl alcohol in sequence for ultrasonic cleaning for 15+/-3 min;
step two: gluing and bonding;
fixing a sealing tube seat 6 on a clamp, picking 730 glue by using a toothpick or using an automatic glue dispenser to uniformly point 6 points on the sealing tube seat 6 according to the appearance of a silicon resonance pressure sensitive chip 2, embedding the silicon resonance pressure sensitive chip 2 into the sealing tube seat, pressing the upper part of a chip upper cover 201 of the silicon resonance pressure sensitive chip 2 by using a ceramic rod, ensuring that an external pressure hole on the sealing tube seat 6 corresponds to a pressure sensing through hole 2031 of a stress isolation layer 203, continuously picking 730 glue by using the toothpick or using an automatic glue dispenser to carry out glue dispensing, protecting the kovar alloy pins 3 by corresponding to the through holes of a ceramic ring of the special clamp, and taking out the ceramic ring after the glue is coated;
step three: curing the glue;
placing the sealing tube seat 6 bonded with the silicon resonance pressure sensitive chip 2 in the second step in a constant temperature and humidity environment for curing for 20-30 hours;
step four: bonding the electrode bonding wire 4;
step four, first: fixing the sealing tube seat 6 on a fixture, and welding the electrode bonding lead 4 and the extraction electrode 3050 together at a position where the diameter of the electrode bonding lead 4 on the surface of the extraction electrode 3050 is 2.5 times from the tip of the chopper;
step four, two: welding the other end of the electrode bonding wire 4 on the kovar alloy pin 3 through a hot welding pen, wherein the length of the electrode bonding wire 4 is automatically formed when two points are pressed and welded;
and step four, three: carrying out a breaking force test on the electrode bonding lead 4 until the breaking force meets the design requirement;
step five: performing insulation test on the Kovar alloy pin 3 and the sealing tube seat 6;
an insulation resistance tester is adopted to test insulation resistance between each pin of the kovar alloy pins 3 and the sealing tube seat 6, and the resistance is larger than a design limit value;
step six: basic performance test of the silicon resonance pressure sensitive chip 2;
the water absorbing ball is adopted to blow the pressure guiding hole, the pressure change is less than hundreds of hertz, and meanwhile, the temperature frequency is not changed; at this time, the silicon resonance pressure sensitive chip 2 satisfies the design requirement;
step seven: welding the sealing cover plate 1 on the sealing tube seat 6;
placing the sealing cover plate 1 on the sealing tube seat 6, welding by argon arc or electron beam, and then performing penetration test; repeating the fifth step;
step eight: plugging the sealing tube seat 6;
firstly sealing a vacuumizing hole 102 with the diameter of 1.3mm by using phi 2 steel balls, and then sealing and welding a vacuumized closed cavity by using electron beam welding;
thus, the encapsulation of the resonance pressure sensitive chip probe of the vacuum encapsulation structure is completed;
step nine: electrically testing the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
performing electrical test under constant normal pressure, and stabilizing the resonance pressure sensitive chip probe to be qualified in less than 3 seconds when the resonance pressure sensitive chip probe does not generate frequency hopping phenomenon and the frequency changes towards one direction;
step ten: performing pressure fatigue and aging tests on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
the resonance pressure sensitive chip probe is arranged on the clamp and is connected with the pneumatic fatigue machine or the hydraulic fatigue machine, the fatigue times are 5000/10000, and the temperature aging experiment is carried out in a high-low temperature test box, so that the internal stress of the resonance pressure sensitive chip probe is released together, and the output stability of the resonance pressure sensitive chip of the vacuum packaging structure is improved;
step eleven: performing air tightness detection on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
connecting the resonance pressure sensitive chip probe with a pressure controller for air tightness detection, wherein the pressure change value is not more than +/-2 Pa, and the air tightness of the resonance pressure sensitive chip probe is qualified at the moment;
step twelve: and (3) performing laser marking and screening on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging, and transferring to the next production stage.
The working principle of the invention is as follows:
the invention can reduce the pressure difference between the chip sealing cavity and the external working environment based on the secondary vacuum packaging of the chip probe, seal the silicon resonance pressure sensitive chip 2 inside the sealing tube seat 6, weld the chip electrode and the kovar alloy pin 3 through the electrode bonding lead 4, transmit the sensor signal, and meanwhile the kovar alloy pin 3 ensures the air tightness inside the whole sealing tube seat 6.
Claims (8)
1. A resonance pressure sensitive chip probe of a vacuum packaging structure is characterized in that: the device comprises a sealing cover plate (1), a silicon resonance pressure sensitive chip (2), kovar alloy pins (3), electrode bonding wires (4), a probe medium transmission channel (5) and a sealing tube seat (6);
the upper end face of the sealing tube seat (6) is a sealing cover plate contact surface (601), a three-level stepped groove is formed in the sealing cover plate contact surface (601), a middle stepped surface of the stepped groove is a lead hole surface (604), a lower stepped surface of the stepped groove is a chip bonding surface (602), a probe medium transmission channel (5) is formed in the chip bonding surface (602), a plurality of lead holes (603) are vertically formed in the lead hole surface (604), an annular sealing groove (605) is formed in the middle of the outer cylindrical surface of the sealing tube seat (6), and a pressure buffer groove (606) is formed in the lower portion of the outer cylindrical surface of the sealing tube seat (6);
the Kovar alloy pins (3) are vertically arranged on lead holes (603) of the sealing tube seat (6) in a glass sintering mode, the silicon resonance pressure sensitive chip (2) is arranged on a chip bonding surface (602) of the sealing tube seat (6) in an adhesive mode, a gap is reserved between the silicon resonance pressure sensitive chip (2) and the side wall of the stepped groove, and the silicon resonance pressure sensitive chip (2) and the Kovar alloy pins (3) are connected through electrode bonding leads (4); the sealing cover plate (1) is arranged on the contact surface (601) of the sealing cover plate, and a closed cavity for protecting the silicon resonance pressure sensitive chip (2) is formed between the probe medium transmission channel (5) and the three-stage stepped groove of the sealing tube seat (6);
the silicon resonance pressure sensitive chip (2) comprises a chip upper cover (201), a resonance layer (202), a silicon-based substrate (2021) and a stress isolation layer (203), wherein the chip upper cover (201), the resonance layer (202), the silicon-based substrate (2021) and the stress isolation layer (203) are sequentially connected from top to bottom and are made into a whole, an inverted trapezoid pressure sensing groove is formed in the lower end face of the silicon-based substrate (2021), an absolute cavity is formed between the chip upper cover (201) and the silicon-based substrate (2021), and the resonance layer (202) is located in the absolute cavity.
2. The vacuum packaging structure resonant pressure sensitive chip probe of claim 1, wherein: the middle part of the stress isolation layer (203) is provided with a pressure sensing through hole (2031).
3. The vacuum packaging structure of claim 2, wherein the resonant pressure sensitive chip probe is characterized in that: the resonance layer (202) comprises four leading-out electrodes (3050), two driving electrodes (3023), a standby electrode (3024), two sensitive comb teeth electrodes (3025), two stable beams (3026), two transverse pull beams (3027), an anchor block (3028) and an electrode passage (3029),
two driving electrodes (3023) are arranged in parallel up and down, an extraction electrode (3050) is respectively arranged on the left side and the right side of each driving electrode (3023), a sensitive comb electrode (3025) is arranged on the opposite side of each driving electrode (3023), a stable beam (3026) is respectively arranged on the inner side of each sensitive comb electrode (3025), a transverse pulling beam (3027) is respectively arranged on the inner side of each stable beam (3026), an anchor block (3028) is arranged between each transverse pulling beam (3027), and the anchor blocks (3028) are connected with a spare electrode (3024) through an electrode passage (3029).
4. A vacuum packaging structure resonant pressure sensitive chip probe as defined in claim 3, wherein: the end of each transverse tension beam (3027) is of a Y-shaped beam structure.
5. The vacuum packaging structure of claim 4, wherein the resonant pressure sensitive chip probe is characterized in that: each stabilizing beam (3026) comprises two stabilizing units which are symmetrical left and right,
each stabilizing unit comprises a first connecting support beam (901), a first cable-stayed beam parallel support beam (901-1), a first cable-stayed beam vertical support beam (901-2), a first parallel support beam vertical beam (901-3), a first cable-stayed beam stabilizing beam (901-4) and a second cable-stayed beam stabilizing beam (901-5),
a trapezoid structure is formed among the first cable-stayed beam parallel support beam (901-1), the first cable-stayed beam stabilizing beam (901-4), the second cable-stayed beam stabilizing beam (901-5) and the sensitive comb tooth electrode (3025), the first cable-stayed beam vertical support beam (901-2) and the first parallel support beam vertical beam (901-3) are vertical to the first cable-stayed beam parallel support beam (901-1), right triangles are formed between the first cable-stayed beam vertical support beam (901-2) and the first parallel support beam vertical beam (901-3) and the first cable-stayed beam stabilizing beam (901-4) and the second cable-stayed beam stabilizing beam (901-5) as well as between the first cable-stayed beam parallel support beam (901-1),
one end of the first connecting support beam (901) coincides with an intersection point of the first cable-stayed beam vertical support beam (901-2) and the first cable-stayed beam parallel support beam (901-1), and the other end of the first connecting support beam (901) coincides with an intersection point of the first parallel support beam vertical beam (901-3) and the second cable-stayed beam stabilizing beam (901-5).
6. The vacuum packaging structure of claim 5, wherein the resonant pressure sensitive chip probe is characterized in that: the probe medium transmission channel (5) comprises a pressure guiding hole (501), an external pressure hole (502) and an internal pressure pipeline (503),
the pressure guiding hole (501) is formed in the chip bonding surface (602) and is communicated with the silicon-based substrate (2021), the external pressure hole (502) is formed in the annular sealing groove (605), and the pressure guiding hole (501) is connected with the external pressure hole (502) through an internal pressure pipeline (503).
7. The vacuum packaging structure of claim 6, wherein the resonant pressure sensitive chip probe is characterized in that: the sealing cover plate (1) comprises a T-shaped table (101), a vacuumizing hole (102), a round boss (103) and a notch (104),
the circular boss (103) is embedded in a groove on the upper end face of the T-shaped table (101), the T-shaped table (101) is provided with vacuumizing holes (102) in the vertical direction, and four openings (104) are uniformly formed in the circular boss (103).
8. A method of packaging a resonant pressure sensitive chip probe for a vacuum package structure as recited in claim 7, wherein: it comprises the following steps:
step one: manufacturing and cleaning a sealing tube seat (6);
the glass slurry sinters the lead hole (603) and the upper and lower pins in the sealing tube seat (6) together to form a sealing pin structure, and the sealing tube seat (6) is made of stainless steel;
respectively clamping a silk cleaning sealing tube seat (6) adhered with acetone and absolute ethyl alcohol by using stainless steel tweezers with the heads coated with polytetrafluoroethylene, cleaning the sealing tube seat for more than 20s by using absolute ethyl alcohol, and drying the sealing tube seat in a drying oven; placing the silicon resonance pressure sensitive chip (2) into acetone and absolute ethyl alcohol in sequence, respectively carrying out ultrasonic cleaning on the sealing tube seat (6) and the silicon resonance pressure sensitive chip (2) for 15min, and placing the special fixture ceramic ring into the acetone and the absolute ethyl alcohol in sequence for ultrasonic cleaning for 15+/-3 min;
step two: gluing and bonding;
fixing a sealing tube seat (6) on a clamp, picking 730 glue by using a toothpick or using an automatic dispenser to uniformly dot 6 points on the sealing tube seat (6) according to the appearance of a silicon resonance pressure sensitive chip (2), embedding the silicon resonance pressure sensitive chip (2) into the sealing tube seat, pressing the upper part of a chip upper cover (201) of the silicon resonance pressure sensitive chip (2) by using a ceramic rod, ensuring that an external pressure hole on the sealing tube seat (6) corresponds to a pressure sensing through hole (2031) of a stress isolation layer (203), continuously picking 730 glue by using the toothpick or using an automatic dispenser to dispense glue, protecting the kovar alloy pins (3) corresponding to the through holes of a ceramic ring of the special clamp, and taking out the ceramic ring after the glue is coated;
step three: curing the glue;
placing the sealing tube seat (6) bonded with the silicon resonance pressure sensitive chip (2) in the second step in a constant temperature and humidity environment for curing for 20-30 hours;
step four: bonding the electrode bonding wire (4);
step four, first: fixing a sealing tube seat (6) on a fixture, and welding the electrode bonding wire (4) and the extraction electrode (3050) together at a position where the diameter of the tip of the chopper is 2.5 times that of the electrode bonding wire (4) on the surface of the extraction electrode (3050);
step four, two: welding the other end of the electrode bonding wire (4) on the kovar alloy pin (3) through a hot welding pen, wherein the length of the electrode bonding wire (4) is automatically formed when two points are pressed and welded;
and step four, three: carrying out a breaking force test on the electrode bonding lead (4) until the breaking force meets the design requirement;
step five: performing insulation test on the Kovar alloy pins (3) and the sealing tube seat (6);
an insulation resistance tester is adopted to test insulation resistance between each pin of the kovar alloy pins (3) and the sealing tube seat (6), and the resistance is larger than a design limit value;
step six: basic performance test of the silicon resonance pressure sensitive chip (2);
the water absorbing ball is adopted to blow the pressure guiding hole, the pressure change is less than hundreds of hertz, and meanwhile, the temperature frequency is not changed; at the moment, the silicon resonance pressure sensitive chip (2) meets the design requirement;
step seven: welding the sealing cover plate (1) on the sealing tube seat (6);
placing the sealing cover plate (1) on a sealing tube seat (6), welding by using argon arc or electron beam, and then performing penetration test; repeating the fifth step;
step eight: plugging a sealing tube seat (6);
firstly sealing a vacuumizing hole (102) with the diameter of 1.3mm by using phi 2 steel balls, and then sealing and welding a vacuumized closed cavity by adopting electron beam welding;
thus, the encapsulation of the resonance pressure sensitive chip probe of the vacuum encapsulation structure is completed;
step nine: electrically testing the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
performing electrical test under constant normal pressure, and stabilizing the resonance pressure sensitive chip probe to be qualified in less than 3 seconds when the resonance pressure sensitive chip probe does not generate frequency hopping phenomenon and the frequency changes towards one direction;
step ten: performing pressure fatigue and aging tests on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
the resonance pressure sensitive chip probe is arranged on the clamp and is connected with the pneumatic fatigue machine or the hydraulic fatigue machine, the fatigue times are 5000/10000, and the temperature aging experiment is carried out in a high-low temperature test box, so that the internal stress of the resonance pressure sensitive chip probe is released together, and the output stability of the resonance pressure sensitive chip of the vacuum packaging structure is improved;
step eleven: performing air tightness detection on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;
connecting the resonance pressure sensitive chip probe with a pressure controller for air tightness detection, wherein the pressure change value is not more than +/-2 Pa, and the air tightness of the resonance pressure sensitive chip probe is qualified at the moment;
step twelve: and (3) performing laser marking and screening on the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging, and transferring to the next production stage.
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