High-reliability miniaturized MEMS automobile pressure sensor

Abstract

The utility model, which belongs to the technical field of the pressure sensor, provides a high-reliability miniaturized MEMS automobile pressure sensor comprising a sealing housing, a circuit unit and a protection structure. 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 utility model, the circuit substrate and the ceramic pressure core body are protected, so that fluid to be detected is only contacted 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 utility model belongs to pressure sensor technical field, more specifically, relate to a kind of miniaturization MEMS automobile pressure sensor of high reliability. BACKGROUND

[0002] The pressure sensor for measuring fluid pressure signal in passenger car gearbox currently mainly adopts MEMS (MicroElectromechanical System) pressure chip sintering adhesion on shell, gold wire bonding process and spring contact to realize electrical signal connection structure, not only high price, but also complex production process, poor durability, low reliability, connection failure and other defects.In the process of driving, the pressure sensor is damaged about 30,000 kilometers, and must be repaired and replaced. UTILITY MODEL CONTENTS

[0003] The utility model aims at providing a kind of miniaturization MEMS automobile pressure sensor of high reliability, to improve the reliability and durability of pressure sensor.

[0004] To achieve the above object, the utility model adopts the technical scheme of providing a kind of miniaturization MEMS automobile pressure sensor of high reliability, comprising:

[0005] Sealing shell, one end of the sealing shell is connected with lead wire, and the end of the lead wire extends into the inner cavity of the sealing shell;The other end of the sealing shell has a through hole communicating the inner cavity of the sealing shell;

[0006] Circuit unit, including circuit substrate (10) and ceramic pressure core, the circuit substrate (10) is located in the inner cavity of the shell body (1), and is connected with the lead wire;The ceramic pressure core is located on the side of the circuit substrate (10) towards the through hole;

[0007] Protection structure, including protective cap (6) and protective adhesive layer (5), the protective cap (6) is sleeved on the outside of the ceramic pressure core and is connected with the circuit substrate (10), the protective cap (6) has filling adhesive layer (9) between the detection end of the ceramic pressure core, the upper end of the protective cap (6) has adsorption end face;The protective adhesive layer (5) is covered on the circuit substrate (10), and the end face of the protective adhesive layer (5) is attached to the upper part of the protective cap (6).

[0008] As another embodiment of the application, the ceramic pressure core comprises:

[0009] Ceramic circuit board (11), the ceramic circuit board (11) is welded and fixed with the circuit substrate (10);

[0010] A pressure chip (8) has a tin ball at the bottom, and is welded to the side of the ceramic circuit board (11) away from the circuit substrate (10) by the tin ball.

[0011] As another embodiment of the application, the upper end of the ceramic circuit board (11) is provided with a plurality of positioning grooves, and the plurality of positioning grooves are uniformly distributed for connecting the tin ball.

[0012] As another embodiment of the application, the inner side wall of the protective cap (6) is attached 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.

[0013] As another embodiment of the application, the filling glue layer (9) extends to the lower part of the pressure chip (8) in the thickness direction.

[0014] As another embodiment of the application, the height of the protective cap (6) is greater than the height of the ceramic pressure core, the upper end of the protective cap (6) has an outwardly extending folding edge structure (7), and the protective glue layer (5) extends to the lower end surface of the folding edge structure (7) in the thickness direction.

[0015] As another embodiment of the application, the bottom of the inner cavity of the sealing shell has a first limiting step (13), the circuit substrate (10) is located on the first limiting step (13) and is limited by the protective glue layer (5), and a gap is left between the circuit substrate (10) and the bottom of the inner cavity of the sealing shell.

[0016] As another embodiment of the application, the sealing shell comprises a shell body (1) and a shell cover, the lead wire penetrates through the shell body (1), and the through hole is formed on the shell cover; the shell cover is welded and sealed with the shell body (1).

[0017] The high-reliability miniaturized MEMS automobile pressure sensor has the advantages that: compared with the prior art, the high-reliability miniaturized MEMS automobile pressure sensor of the utility model realizes the transmission of electrical signals by connecting the sintered shell with the circuit substrate, guarantees the characteristics of stable and reliable electrical connection, separates the ceramic pressure core on the circuit substrate from other components, increases the protection of the ceramic pressure core, forms the protective glue layer and the filling glue layer by pouring glue, realizes the protection of the circuit substrate and the ceramic pressure core, makes the to-be-measured fluid only contact the detection end of the ceramic pressure core, improves the reliability and durability of the pressure sensor, and makes the pressure sensor more suitable for high-temperature, high-humidity and high-corrosion working environments. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0019] Figure 1 The structure schematic diagram of the high-reliability miniaturized MEMS automobile pressure sensor provided by the embodiment of the present application is shown in the figure.

[0020] Figure 2 The structure schematic diagram of the high-reliability miniaturized MEMS automobile pressure sensor provided by the embodiment of the present application is shown in the figure.

[0021] Figure 3 The structure schematic diagram of the circuit substrate provided by the embodiment of the present application is shown in the figure.

[0022] Figure 4 The installation position schematic diagram of the protective cap provided by the embodiment of the present application is shown in the figure.

[0023] Figure 5 The structure schematic diagram of the shell provided by the embodiment of the present application is shown in the figure.

[0024] In the figure: 1, shell body; 2, pin connecting part; 3, metal pin; 4, glass insulation structure; 5, protective adhesive layer; 6, protective cap; 7, folding edge structure; 8, pressure chip; 9, filling adhesive layer; 10, circuit substrate; 11, ceramic circuit board; 12, connecting hole; 13, first limiting step; 14, second limiting step. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the following will further describe the present application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0026] Please refer to Figures 1 to 5The utility model provides a high reliability's miniaturized MEMS automobile pressure sensor, and compared with the prior art, the sintering shell is connected with the circuit substrate 10 to realize the transmission of electric signal, guarantees the characteristics of stable and reliable electric connection, the protection cap 6 separates the ceramic pressure core body on the circuit substrate 10 from other components, increases the protection of ceramic pressure core body, and through the filling of adhesive forms the protection adhesive layer 5 and filling adhesive layer 9, realizes the protection of circuit substrate 10 and ceramic pressure core body, makes the fluid to be measured only contact with the detection end of ceramic pressure core body, improves the reliability and durability of pressure sensor, makes the pressure sensor more suitable for high temperature and high humidity and high corrosive working environment, in addition, the adsorption end face is convenient for negative pressure adsorption installation.

[0027] The utility model provides a high reliability's miniaturized MEMS automobile pressure sensor, and compared with the prior art, the sintering shell is connected with the circuit substrate 10 to realize the transmission of electric signal, guarantees the characteristics of stable and reliable electric connection, the protection cap 6 separates the ceramic pressure core body on the circuit substrate 10 from other components, increases the protection of ceramic pressure core body, and through the filling of adhesive forms the protection adhesive layer 5 and filling adhesive layer 9, realizes the protection of circuit substrate 10 and ceramic pressure core body, makes the fluid to be measured only contact with the detection end of ceramic pressure core body, improves the reliability and durability of pressure sensor, makes the pressure sensor more suitable for high temperature and high humidity and high corrosive working environment, in addition, the adsorption end face is convenient for negative pressure adsorption installation.

[0028] The above-mentioned pressure sensor is designed based on domestic silicon piezoresistive MEMS flip-chip pressure chip, combined with domestic ASIC chip, and has the advantages of rapid and sensitive response, high test precision, few components, simple assembly, low cost and the like.

[0029] The sealing shell comprises a shell body 1 and a shell cover, the lead wire penetrates through the shell body 1, and the through hole is arranged on the shell cover; the shell cover is welded and sealed with the shell body 1. The lead wire is a metal pin 3, and the metal pin 3 and the shell body 1 form a sintering seat shell. A glass insulation structure 4 is formed between the metal pin 3 and the shell body 1.

[0030] Specifically, other electronic components are mounted on the circuit substrate 10. In the mounting, first, the corresponding electronic components, the ceramic pressure core and the protective cap 6 are mounted on the circuit substrate 10, then the circuit substrate 10 is placed in the interior of the housing body and is tin soldered with the metal pin 3 of the housing bottom to complete the connection of the circuit; then the glue is poured in the inner cavity of the housing body, a part of the glue is poured in the interior of the protective cap 6, the glue is solidified to form the filling glue layer 9 for protecting the ceramic pressure core, another part is poured on the upper layer of the circuit substrate 10 and covers the electronic components on the circuit substrate 10, the glue is solidified to form the protective glue layer 5, and the protective glue layer 5 does not exceed the upper end of the protective cap 6; finally, the housing cover is mounted.

[0031] In use, the fluid to be measured enters the detection cavity between the protective glue layer 5 and the housing cover through the through hole of the housing cover, the fluid to be measured in the detection cavity enters the interior of the protective cap 6 from the opening of the protective cap 6 and contacts the detection end of the ceramic pressure core to realize pressure detection. The result of the detection is transmitted by the ceramic pressure core to the circuit substrate 10, and then the electrical signal transmission is completed by the metal pin 3.

[0032] In some possible embodiments, referring to 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 with the circuit substrate 10; the bottom of the pressure chip 8 has a tin 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 tin ball.

[0033] The pressure chip 8 is a silicon piezoresistive MEMS flip-chip pressure chip 8, and the pressure chip 8 is welded on the ceramic circuit board 11 by means of reflow soldering. Specifically, the bottom of the pressure chip 8 is on the side of the pressure chip 8 away from the test end, and only the tin ball is welded on the bottom, and the tin ball is welded with the ceramic circuit board 11 to form a connecting structure, and the tin ball can also support the pressure chip 8.

[0034] In the mounting, first, the tin ball is planted on the bottom of the pressure chip 8, and the tin ball can be arranged at the four corners of the bottom surface of the pressure chip 8; then the tin ball is welded on the ceramic circuit board 11 by means of reflow soldering; finally, the ceramic circuit board 11 and the electronic components are welded on the circuit substrate 10 by means of reflow soldering. The circuit substrate 10 can adopt an epoxy circuit substrate 10.

[0035] Correspondingly, a plurality of positioning grooves are left on the upper end of the ceramic circuit board 11, and the plurality of positioning grooves are uniformly distributed for connecting the tin balls. The number of the positioning grooves is consistent with the number of the tin balls, and the positioning grooves correspond to the tin balls one by one. The positioning grooves are groove bodies recessed on the ceramic circuit board 11, so as to facilitate the determination of the position of the tin ball and increase the contact area of the ceramic circuit board 11 and the tin ball.

[0036] Through the cooperation of the tin ball and the positioning groove, not only the effective connection of the ceramic circuit board 11 and the pressure chip 8 can be realized, but also the transmission effect of the electric signal can be ensured.

[0037] In some possible embodiments, referring to Figure 4 The inner side wall of the protective cap 6 is attached 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, and the filling glue layer 9 fills and covers the gap.

[0038] After the ceramic circuit board 11 of the ceramic pressure core is welded on the circuit substrate 10, the protective cap 6 is adsorbed by the negative pressure suction nozzle of the negative pressure tooling, and is sleeved on the outer side of the ceramic pressure core from the detection end 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 on the circuit substrate 10 by curing through dispensing between the protective cap 6 and the circuit substrate 10. Finally, the protective cap 6 is filled with glue, forming a filling glue layer 9, to achieve protection of the ceramic pressure core.

[0039] Since the ceramic pressure core includes the ceramic circuit board 11 and the pressure chip 8, the area of the ceramic circuit board 11 is greater than that of the pressure chip 8. The inner side wall of the protective cap 6 is attached to the outer side wall of the ceramic circuit board 11 or a gap is left between the inner side wall of the protective cap 6 and the outer side wall of the ceramic circuit board 11. When the inner side wall of the protective cap 6 is attached to the outer side wall of the ceramic circuit board 11, the filling glue layer 9 only covers the upper end of the ceramic circuit board 11 and covers the connection position of the tin ball; when the inner side wall of the protective cap 6 and the outer side wall of the ceramic circuit board 11 exist a gap, the filling glue layer 9 fills the gap and extends upward to cover the connection position of the tin ball.

[0040] The filling glue layer 9 extends to the lower part of the pressure chip 8 in the thickness direction. The filling glue layer 9 completely covers the ceramic circuit board 11 and is attached to the outer side wall of the lower part of the pressure chip 8, protecting the ceramic circuit board 11 from contacting the fluid to be measured. The filling glue layer 9 forms a protective layer on the outer side of the ceramic circuit board 11, improving the service life of the ceramic pressure core in a high-temperature, high-humidity and highly corrosive working environment.

[0041] The height of the protective cap 6 is greater than the height of the ceramic pressure core, and the upper end of the protective cap 6 has a flange structure 7 extending outwardly; the protective glue layer 5 extends to the lower end surface of the flange structure 7 in the thickness direction. The protective cap 6 protrudes from the ceramic pressure core to completely wrap the ceramic pressure core, and when filling glue in the inside, a detection end of the pressure chip 8 is left. The upper end surface of the flange structure 7 forms an adsorption end surface.

[0042] A flange structure 7 is formed at the upper end of the protective cap 6 to expand outwardly without affecting the installation and use. Since the protective cap 6 needs to be adsorbed and positioned by a tool using negative pressure during installation, the flange structure 7 can increase the contact area between the negative pressure suction nozzle and the protective cap 6, facilitating the adsorption of the negative pressure suction nozzle. The protective cap 6 is made by injection molding, and the upper end of the protective cap 6 forms the flange structure 7, which can be integrally injection molded during injection molding.

[0043] In some possible embodiments, referring to Figure 5 , the bottom of the inner cavity of the shell body 1 has a first limiting step 13, and the circuit board 10 is located on the first limiting step 13 and is limited by the protective adhesive layer 5. The circuit board 10 has a gap with the bottom of the inner cavity of the shell body 1.

[0044] The first limiting step 13 is formed on the inner side wall of the bottom of the shell body 1, and there is a height difference between the first limiting step 13 and the bottom surface of the inner cavity of the shell body 1. The circuit board 10 is placed from the opening end of the shell body 1 and is attached to the first limiting step 13.

[0045] The circuit board 10 is provided with a connecting hole 12 allowing the metal pin 3 to pass through, and the metal pin 3 is fixed by soldering with the hole wall of the connecting hole 12. The metal pin 3 is fixed with the shell, and during installation, only the connecting hole 12 of the circuit board 10 is required to correspond to the metal pin 3, and the circuit board 10 is placed into the shell. The metal pin 3 penetrates through the connecting hole 12, and the metal pin 3 is fixed by soldering with the hole wall of the connecting hole 12 and the circuit board 10 around the connecting hole 12.

[0046] The circuit board 10 is fixed on the first limiting step 13 by means of the protective adhesive layer 5. After curing, the lower end surface of the protective adhesive layer 5 is connected with the circuit board 10, the circumferential surface is connected with the shell, and the part of the metal pin 3 extending out of the circuit board 10 is completely wrapped and covered.

[0047] In some possible embodiments, referring to Figure 5 , the upper part of the inner cavity of the shell body 1 has a second limiting step 14, and the shell cover is located on the second limiting step 14 and is sealed by welding with the shell body 1.

[0048] 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 is attached to the second limiting step 14. The circumferential side wall of the shell cover is attached to the inner side wall of the shell body 1, and the interface is sealed by laser welding.

[0049] The shell cover is laser welded with the shell to seal the other end of the shell by a glass sintering process, which is bidirectional sealing to reduce the leakage probability, and there is no need to install a sealing ring for sealing, thereby improving the overall reliability.

[0050] For the glass sintering process of the shell, in order to ensure the sealing of the metal pin 3 and the shell, the shell body 1 has a downward extending pin connecting part 2 at the bottom, the outer diameter of the pin connecting part 2 is smaller than the outer diameter of the shell body 1; the metal pin 3 penetrates through the pin connecting part 2. The pin connecting part 2 increases the contact area of the metal pin 3 and the glass insulation structure 4, and ensures the sealing effect of the shell.

[0051] The glass insulation structure 4 between the shell 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 circumferential glass insulation structure 4 is uniform.

[0052] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. High reliability miniaturized MEMS automotive pressure sensor, characterized by: include: A sealed housing, one end of which is connected to a lead wire, the end of which extends into the inner cavity of the sealed housing; and the other end of the sealed housing has a through hole communicating with the inner cavity of the sealed housing; 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 sealed housing and is connected to the lead; and the ceramic pressure core is provided on a side of the circuit substrate (10) facing the through hole. A protective structure comprises a protective cap (6) and a protective adhesive layer (5); the protective cap (6) is sleeved on the outside of the ceramic pressure core and connected to the circuit substrate (10); a filling adhesive layer (9) is provided between the protective cap (6) and the detection end of the ceramic pressure core; the upper end of the protective cap (6) has an adsorption end face; the protective adhesive layer (5) covers the circuit substrate (10), and the end face of the protective adhesive layer (5) is attached to the upper part of the protective cap (6).

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) has a solder ball at its bottom, 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, wherein: 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 2, characterized in that: The filling rubber 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 upper end of the protective cap (6) has a folded edge structure (7) extending outward; the protective rubber layer (5) extends to the lower end surface of the folded edge structure (7) along the thickness direction.

7. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, wherein: The bottom of the inner cavity of the sealed housing 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 sealed housing.

8. The high-reliability miniaturized MEMS automotive pressure sensor according to claim 1, wherein: The sealed housing comprises a housing body (1) and a housing cover, the lead wire passes through the housing body (1), and the through hole is provided on the housing cover; the housing cover and the housing body (1) are welded and sealed.

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