High-reliability miniaturized MEMS automobile pressure sensor

Abstract

The invention, which belongs to the technical field of the pressure sensor, provides a high-reliability miniaturized MEMS automobile pressure sensor comprising a sintered shell, a circuit unit, a protection structure and a shell cover. The circuit unit comprises a circuit substrate and a ceramic pressure core body, the protection structure comprises a protection cap and a protection glue layer, the protection cap sleeves the outer side of the ceramic pressure core body and is connected with the circuit substrate, and a filling glue layer is arranged between the protection cap and the detection end of the ceramic pressure core body; the protective glue layer covers the circuit substrate, and the end face of the protective glue layer is attached to the upper portion of the protective cap. According to the high-reliability miniaturized MEMS automobile pressure sensor provided by the invention, the circuit substrate and the ceramic pressure core body are protected, so that a fluid to be detected is only in contact with the detection end of the ceramic pressure core body, the reliability and durability of the pressure sensor are improved, and the pressure sensor is more suitable for a high-temperature, high-humidity and high-corrosion working environment.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure sensors, and more specifically, relates to a high-reliability miniaturized MEMS automobile pressure sensor. Background Art

[0002] At present, the pressure sensor for measuring fluid pressure signals in passenger car gearboxes mainly adopts a structure in which a MEMS (MicroElectromechanical System) pressure chip is sintered and bonded to the housing, and the gold wire bonding process is used to contact the spring to achieve electrical signal connection. Not only is the price high, but there are also defects such as complex production process, poor durability, low reliability, and easy connection failure. During actual vehicle driving, the pressure sensor is basically damaged after about 30,000 kilometers and must be repaired and replaced. Summary of the invention

[0003] The object of the present invention is to provide a high-reliability miniaturized MEMS automobile pressure sensor, aiming to improve the reliability and durability of the pressure sensor.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a high-reliability miniaturized MEMS automobile pressure sensor, comprising: A sintered shell, comprising a shell body and a metal pin, wherein the metal pin passes through a bottom plate of the shell body, and a glass insulating structure is provided between the metal pin and the shell body; The circuit unit comprises a circuit substrate and a ceramic pressure core, wherein the circuit substrate is located in the inner cavity of the shell body, and the ceramic pressure core is connected to a side of the circuit substrate facing the opening of the shell body; the end of the metal pin is connected to the circuit substrate; The protection structure comprises a protection cap and a protection rubber layer, wherein the protection cap is sleeved on the outer side of the ceramic pressure core and connected to the circuit substrate, and a filling rubber layer is provided between the protection cap and the detection end of the ceramic pressure core; the protection rubber layer covers the circuit substrate, and the end surface of the protection rubber layer is attached to the upper part of the protection cap; A shell cover is connected to the port of the shell body, a through hole is left on the shell cover, a detection cavity is formed between the shell cover and the end face of the protective rubber layer, and the detection cavity connects the through hole and the detection end of the ceramic pressure core.

[0005] As another embodiment of the present application, the ceramic pressure core comprises: A ceramic circuit board, wherein the ceramic circuit board is fixed to the circuit substrate by welding; A pressure chip, wherein the bottom of the pressure chip has a solder ball, and the pressure chip is soldered to a side of the ceramic circuit board away from the circuit substrate by means of the solder ball.

[0006] As another embodiment of the present application, a plurality of positioning grooves are reserved at the upper end of the ceramic circuit board, and the plurality of positioning grooves are evenly distributed for connecting the solder balls.

[0007] As another embodiment of the present application, the inner wall of the protective cap is fitted to the ceramic pressure core or a gap is left between the inner wall of the protective cap and the outer wall of the ceramic pressure core.

[0008] As another embodiment of the present application, the filling glue layer extends to the lower part of the pressure chip along the thickness direction.

[0009] As another embodiment of the present application, the height of the protective cap is greater than the height of the ceramic pressure core; and the protective rubber layer extends to the lower end surface of the folded edge structure along the thickness direction.

[0010] As another embodiment of the present application, the bottom of the inner cavity of the shell body has a first limiting step, the circuit substrate is located on the first limiting step and is limited by the protective rubber layer, and a gap is left between the circuit substrate and the bottom of the inner cavity of the shell body.

[0011] As another embodiment of the present application, a connection hole is provided on the circuit substrate to allow the metal pin to pass through, and the metal pin is fixed to the hole wall of the connection hole by soldering.

[0012] As another embodiment of the present application, the upper portion of the inner cavity of the shell body has a second limiting step, the shell cover is located on the second limiting step, and the shell cover is welded and sealed to the shell body.

[0013] As another embodiment of the present application, the bottom of the shell body has a pin connecting portion extending downward, and the outer diameter of the pin connecting portion is smaller than the outer diameter of the shell body; the metal pin passes through the pin connecting portion.

[0014] The beneficial effects of the high-reliability miniaturized MEMS automobile pressure sensor provided by the present invention are as follows: compared with the prior art, the high-reliability miniaturized MEMS automobile pressure sensor of the present invention has a sintered shell connected to a circuit substrate to realize the transmission of electrical signals, thereby ensuring the characteristics of stable and reliable electrical connection; the protective cap separates the ceramic pressure core on the circuit substrate from other components, thereby increasing the protection of the ceramic pressure core, and forms a protective glue layer and a filling glue layer by glue pouring, thereby realizing the protection of the circuit substrate and the ceramic pressure core, so that the fluid to be measured only contacts the detection end of the ceramic pressure core, thereby improving the reliability and durability of the pressure sensor, and making the pressure sensor more suitable for high temperature, high humidity and high corrosive working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of the structure of a high-reliability miniaturized MEMS automobile pressure sensor provided by an embodiment of the present invention; Figure 2 A schematic structural diagram of a high-reliability miniaturized MEMS automobile pressure sensor provided by an embodiment of the present invention with its shell cover removed; Figure 3 A schematic diagram of the structure of a circuit substrate provided by an embodiment of the present invention; Figure 4 A schematic diagram of the installation position of the protective cap provided in an embodiment of the present invention; Figure 5 A schematic structural diagram of a housing provided in an embodiment of the present invention.

[0017] In the figure: 1. Shell body; 2. Pin connection part; 3. Metal pin; 4. Glass insulation structure; 5. Protective rubber layer; 6. Protective cap; 7. Folding structure; 8. Pressure chip; 9. Filling rubber layer; 10. Circuit substrate; 11. Ceramic circuit board; 12. Connection hole; 13. First limit step; 14. Second limit step. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] See also Figures 1 to 5The high-reliability miniaturized MEMS automotive pressure sensor provided by the present invention is now described. The high-reliability miniaturized MEMS automotive pressure sensor comprises a sintered shell, a circuit unit, a protective structure and a shell cover; the sintered shell comprises a shell body 1 and a metal pin 3, the metal pin 3 penetrates the bottom plate of the shell body 1, and a glass insulating structure 4 is provided between the metal pin 3 and the shell body 1; the circuit unit comprises a circuit substrate 10 and a ceramic pressure core, the circuit substrate 10 is located in the inner cavity of the shell body 1, and the side of the circuit substrate 10 opening toward the shell body 1 is connected to the ceramic pressure core; the end of the metal pin 3 is connected to the ceramic pressure core; The protective structure includes a protective cap 6 and a protective rubber layer 5, the protective cap 6 is sleeved on the outside of the ceramic pressure core and connected to the circuit substrate 10, and a filling rubber layer 9 is provided between the protective cap 6 and the detection end of the ceramic pressure core; the protective rubber layer 5 covers the circuit substrate 10, and the end face of the protective rubber layer 5 is attached to the upper part of the protective cap 6; the shell cover is connected to the port of the shell body 1, and a through hole is left on the shell cover, and a detection cavity is formed between the shell cover and the end face of the protective rubber layer 5, and the detection cavity connects the through hole and the detection end of the ceramic pressure core.

[0020] Compared with the prior art, the high-reliability miniaturized MEMS automotive pressure sensor provided by the present invention realizes the transmission of electrical signals through the connection of the sintered shell with the circuit substrate 10, thereby ensuring the characteristics of stable and reliable electrical connection; the protective cap 6 separates the ceramic pressure core on the circuit substrate 10 from other components, thereby increasing the protection of the ceramic pressure core; and the protective glue layer 5 and the filling glue layer 9 are formed by glue pouring, thereby realizing the protection of the circuit substrate 10 and the ceramic pressure core, so that the fluid to be measured only contacts the detection end of the ceramic pressure core, thereby improving the reliability and durability of the pressure sensor, and making the pressure sensor more suitable for high temperature, high humidity and high corrosive working environments.

[0021] The pressure sensor is designed based on the domestically produced silicon piezoresistive MEMS flip-chip pressure chip 8 and combined with the domestically produced ASIC chip. It has the advantages of rapid and sensitive response, high test accuracy, few components, simple assembly and low cost.

[0022] Specifically, other electronic components are installed on the circuit substrate 10. During installation, firstly, corresponding electronic components, ceramic pressure core and protective cap 6 are installed on the circuit substrate 10, and then the circuit substrate 10 is placed inside the shell and connected to the metal pin 3 at the bottom of the shell by soldering to complete the circuit connection; then, glue is poured into the inner cavity of the shell, a part of the glue is poured into the inside of the protective cap 6, and the glue solidifies to form a filling glue layer 9 to protect the ceramic pressure core, and the other part is poured into the upper layer of the circuit substrate 10 and covers the electronic components on the circuit substrate 10, and the glue solidifies to form a protective glue layer 5, and the protective glue layer 5 does not exceed the upper end of the protective cap 6; finally, the shell cover is installed.

[0023] When in use, the fluid to be tested enters the detection cavity between the protective rubber layer 5 and the shell cover through the through hole of the shell cover, and the fluid to be tested in the detection cavity enters the inner side of the protective cap 6 from the opening of the protective cap 6 and contacts the detection end of the ceramic pressure core to achieve pressure detection. The detection result is transmitted to the circuit substrate 10 by the ceramic pressure core, and then the metal pin 3 completes the electrical signal transmission.

[0024] In some possible embodiments, see Figure 3 The ceramic pressure core includes a ceramic circuit board 11 and a pressure chip 8; the ceramic circuit board 11 is welded and fixed to the circuit substrate 10; the bottom of the pressure chip 8 has a solder ball, and the pressure chip 8 is welded to the side of the ceramic circuit board 11 away from the circuit substrate 10 by means of the solder ball.

[0025] The pressure chip 8 is a silicon piezoresistive MEMS flip-chip pressure chip 8, and the pressure chip 8 is soldered on the ceramic circuit board 11 through a reflow soldering process. Specifically, the side of the pressure chip 8 away from the test end is the bottom of the pressure chip 8, and only a tin ball is soldered to the bottom. The tin ball is soldered to the ceramic circuit board 11 to form a connection structure, and the tin ball can also support the pressure chip 8.

[0026] During installation, firstly, solder balls are planted on the bottom of the pressure chip 8, and the solder balls can be arranged at the four corners of the bottom surface of the pressure chip 8; then the solder balls are soldered on the ceramic circuit board 11 through the reflow soldering process; finally, the ceramic circuit board 11 and the electronic components are soldered on the circuit substrate 10 through the reflow soldering process. The circuit substrate 10 can be an epoxy resin circuit substrate 10.

[0027] Correspondingly, a plurality of positioning grooves are left at the upper end of the ceramic circuit board 11, and the plurality of positioning grooves are evenly distributed for connecting the solder balls. The number of positioning grooves is consistent with the number of solder balls, and the positioning grooves correspond to the solder balls one by one. The positioning grooves are grooves recessed on the ceramic circuit board 11 to facilitate the determination of the position of the solder balls and increase the contact area between the ceramic circuit board 11 and the solder balls.

[0028] Through the cooperation of the solder balls and the positioning grooves, not only can the ceramic circuit board 11 and the pressure chip 8 be effectively connected, but also the transmission effect of the electrical signal can be guaranteed.

[0029] In some possible embodiments, see Figure 4 The protective cap 6 is glued to the circuit substrate 10, the inner wall of the protective cap 6 is attached to the ceramic pressure core or a gap is left between the inner wall of the protective cap 6 and the outer wall of the ceramic pressure core, and the filling glue layer 9 fills and covers the gap.

[0030] After the ceramic circuit board 11 of the ceramic pressure core is welded on the circuit substrate 10, the protective cap 6 is sucked by the negative pressure nozzle of the negative pressure tooling, and the detection end of the ceramic pressure core is sleeved on the outside of the ceramic pressure core until the end of the protective cap 6 is attached to the circuit substrate 10. The protective cap 6 is glued and fixed to the circuit substrate 10 by dispensing and curing between the protective cap 6 and the circuit substrate 10. Finally, glue is poured into the protective cap 6 to form a filling glue layer 9 to protect the ceramic pressure core.

[0031] Since the ceramic pressure core includes a ceramic circuit board 11 and a pressure chip 8, the area of ​​the ceramic circuit board 11 is larger than the area of ​​the pressure chip 8. The inner wall of the protective cap 6 is fitted to the outer wall of the ceramic circuit board 11 or a gap is left between the inner wall of the protective cap 6 and the outer wall of the ceramic circuit board 11. When the inner wall of the protective cap 6 is fitted to the outer wall of the ceramic circuit board 11, the filling rubber layer 9 only covers the upper end of the ceramic circuit board 11 and covers the connection position of the solder ball; when there is a gap between the inner wall of the protective cap 6 and the outer wall of the ceramic circuit board 11, the filling rubber layer 9 fills the gap and extends upward to cover the connection position of the solder ball.

[0032] The filling rubber layer 9 extends to the lower part of the pressure chip 8 in the thickness direction. The filling rubber layer 9 completely covers the ceramic circuit board 11 and fits with the outer side wall of the lower part of the pressure chip 8 to protect the ceramic circuit board 11 from contacting the fluid to be measured. The filling rubber layer 9 forms a protective layer on the outer side of the ceramic circuit board 11, which improves the service life of the ceramic pressure core in a high temperature, high humidity and high corrosive working environment.

[0033] The height of the protective cap 6 is greater than that of the ceramic pressure core, and the upper end of the protective cap 6 has a folded edge structure 7 extending outward; the protective rubber layer 5 extends along the thickness direction to the lower end surface of the folded edge structure 7. The protective cap 6 protrudes from the ceramic pressure core to completely wrap the ceramic pressure core, and when the glue is poured inside, the detection end of the pressure chip 8 is left.

[0034] Under the premise of not affecting installation and use, a folding structure 7 that expands outward is reserved at the upper end of the protective cap 6. Since the protective cap 6 needs to be adsorbed and positioned by a negative pressure tooling during installation, the folding structure 7 can increase the contact area between the negative pressure suction nozzle and the protective cap 6, making it easier to adsorb the negative pressure suction nozzle. The protective cap 6 is made by injection molding, and the folding structure 7 is formed at the upper end of the protective cap 6. During injection molding, the folding structure 7 can be integrally injection molded.

[0035] In some possible embodiments, see Figure 5 The bottom of the inner cavity of the shell body 1 has a first limiting step 13 , the circuit substrate 10 is located on the first limiting step 13 and is limited by the protective rubber layer 5 , and a gap is left between the circuit substrate 10 and the bottom of the inner cavity of the shell body 1 .

[0036] A first limiting step 13 is formed on the inner side wall of the bottom of the housing body 1 , and there is a height difference between the first limiting step 13 and the inner cavity bottom surface of the housing body 1 . The circuit substrate 10 is inserted from the opening end of the housing body 1 and fits on the first limiting step 13 .

[0037] The circuit substrate 10 is provided with a connection hole 12 that allows the metal pin 3 to pass through, and the metal pin 3 is fixed to the hole wall of the connection hole 12 by soldering. The metal pin 3 is connected and fixed to the housing. When installing, it is only necessary to match the connection hole 12 of the circuit substrate 10 with the metal pin 3 and put the circuit substrate 10 into the housing. The metal pin 3 passes through the connection hole 12, and the metal pin 3 is fixed to the hole wall of the connection hole 12 and the circuit substrate 10 around the connection hole 12 by soldering.

[0038] The circuit substrate 10 is fixed on the first limiting step 13 by means of the protective adhesive layer 5. After curing, the protective adhesive layer 5 is connected to the circuit substrate 10 at its lower end surface and to the shell in the circumferential direction, while completely covering the portion of the metal pin 3 extending out of the circuit substrate 10.

[0039] In some possible embodiments, see Figure 5 The upper part of the inner cavity of the shell body 1 has a second limiting step 14, the shell cover is located on the second limiting step 14, and the shell cover is welded and sealed with the shell body 1.

[0040] The second limiting step 14 is located at the upper part of the shell body 1, and the shell cover is embedded at the port of the shell body 1 and fits on the second limiting step 14. The circumferential side wall of the shell cover fits on the inner side wall of the shell body 1, and the interface is sealed by laser welding.

[0041] The shell cover is laser welded to the shell body and the glass sintering process is used to seal the other end of the shell body. The bidirectional seal reduces the chance of leakage and does not require the installation of a sealing ring, thereby improving the overall reliability.

[0042] For the glass sintering process of the shell, in order to ensure the sealing between the metal pin 3 and the shell, a pin connection part 2 extending downward is provided at the bottom of the shell body 1, and the outer diameter of the pin connection part 2 is smaller than the outer diameter of the shell body 1; the metal pin 3 passes through the pin connection part 2. The pin connection part 2 increases the contact area between the metal pin 3 and the glass insulation structure 4, ensuring the sealing effect of the shell.

[0043] The glass insulating structure 4 between the housing and the metal pin 3 is formed by glass sintering. The metal pin 3 is located on the center line of the hole, and the thickness of the glass insulating structure 4 in the circumferential direction is uniform.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. High reliability miniaturized MEMS automotive pressure sensor, characterized by: include: A sintered shell, comprising a shell body (1) and a metal pin (3), wherein the metal pin (3) passes through a bottom plate of the shell body (1), and a glass insulating structure (4) is provided between the metal pin (3) and the shell body (1); The circuit unit comprises a circuit substrate (10) and a ceramic pressure core, wherein the circuit substrate (10) is located in the inner cavity of the housing body (1), and the side of the circuit substrate (10) facing the opening of the housing body (1) is connected to the ceramic pressure core; the end of the metal pin (3) is connected to the circuit substrate (10); The protective structure comprises a protective cap (6) and a protective rubber layer (5), wherein the protective cap (6) is sleeved on the outer side of the ceramic pressure core and connected to the circuit substrate (10), and a filling rubber layer (9) is provided between the protective cap (6) and the detection end of the ceramic pressure core; the protective rubber layer (5) covers the circuit substrate (10), and the end surface of the protective rubber layer (5) is attached to the upper part of the protective cap (6); A shell cover, the shell cover is connected to the port of the shell body (1), a through hole is left on the shell cover, a detection cavity is formed between the shell cover and the end face of the protective rubber layer (5), and the detection cavity is connected to the through hole and the detection end of the ceramic pressure core.

2. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, characterized in that: The ceramic pressure core comprises: A ceramic circuit board (11), wherein the ceramic circuit board (11) is fixed to the circuit substrate (10) by welding; A pressure chip (8), wherein the bottom of the pressure chip (8) has a solder ball, and the pressure chip (8) is soldered to a side of the ceramic circuit board (11) away from the circuit substrate (10) by means of the solder ball.

3. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 2, characterized in that: A plurality of positioning grooves are left at the upper end of the ceramic circuit board (11), and the plurality of positioning grooves are evenly distributed and used for connecting the solder balls.

4. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, characterized in that: The inner side wall of the protective cap (6) is fitted to the ceramic pressure core or a gap is left between the inner side wall of the protective cap (6) and the outer side wall of the ceramic pressure core.

5. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 4, characterized in that: The filling glue layer (9) extends to the lower part of the pressure chip (8) along the thickness direction.

6. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, characterized in that: The height of the protective cap (6) is greater than the height of the ceramic pressure core; and the protective rubber layer (5) extends along the thickness direction to the lower end surface of the folded edge structure (7).

7. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, characterized in that: The bottom of the inner cavity of the shell body (1) has a first limiting step (13), the circuit substrate (10) is located on the first limiting step (13) and is limited by the protective rubber layer (5), and a gap is left between the circuit substrate (10) and the bottom of the inner cavity of the shell body (1).

8. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 7, characterized in that: The circuit substrate (10) is provided with a connection hole (12) for allowing the metal pin (3) to pass through, and the metal pin (3) is fixed to the hole wall of the connection hole (12) by soldering.

9. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, characterized in that: The upper part of the inner cavity of the shell body (1) is provided with a second limiting step (14), the shell cover is located on the second limiting step (14), and the shell cover is welded and sealed with the shell body (1).

10. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, characterized in that: The bottom of the shell body (1) has a pin connection portion (2) extending downwards, the outer diameter of the pin connection portion (2) being smaller than the outer diameter of the shell body (1); the metal pin (3) passes through the pin connection portion (2).

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