Pressure sensor packaging structure

Abstract

The utility model relates to the technical field of pressure sensors, and provides a pressure sensor packaging structure, which comprises a silicon cup and a protective shell, an induction diaphragm is carried on the silicon cup, the silicon cup divides the protective shell into a high-pressure cavity and a low-pressure cavity and is filled with silicone oil, and the high-pressure cavity and the low-pressure cavity are respectively positioned on the front side and the back side of the induction diaphragm. The protective shell is provided with a high-pressure inlet and a low-pressure inlet which correspond to the two cavities respectively, the high-pressure inlet is sealed through a first protective diaphragm, the first protective diaphragm is of a corrugated structure, a protective protrusion is fixed to the portion, on the inner side of the high-pressure cavity, of the protective shell, and the protective protrusion and the first protective diaphragm are arranged in a spaced mode. A plurality of drainage grooves distributed in a radial shape are carved in the surface, facing the first protection membrane, of the protection protrusion. The beneficial effects of the utility model are that overload protection can be carried out on the pressure sensor through multiple protection mechanisms, and the sensing diaphragm is prevented from being damaged.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of pressure sensor, specifically, relate to a pressure sensor packaging structure. BACKGROUND

[0002] The packaging of pressure sensor is a very critical link, which directly determines the performance, reliability, life and application scene of the sensor, protects the fragile silicon micromechanical structure (MEMS chip) while accurately transmitting pressure and realizing stable electrical connection. Among them, the differential pressure sensor is widely used in industrial process control to measure flow, liquid level, etc. In use, the sudden opening and closing of the valve and the start / stop of the pump will generate an instantaneous shock wave in the pipeline, which is several times the normal working pressure. This is the most deadly threat to the differential pressure sensor. The core MEMS silicon diaphragm of the differential pressure sensor is extremely precise and fragile. Pressure overload will directly cause the deformation of the silicon diaphragm to exceed the elastic limit, resulting in plastic deformation, permanent damage or direct rupture. SUMMARY

[0003] The utility model provides a pressure sensor packaging structure, can carry out overload protection to pressure sensor through multiple protection mechanism, prevent sensing diaphragm damage.

[0004] To this end, the technical scheme adopted is as follows:

[0005] A pressure sensor packaging structure, comprising a silicon cup and a protective shell, the silicon cup carries a sensing diaphragm, the silicon cup separates the protective shell into a high-pressure cavity and a low-pressure cavity and fills them with silicon oil, the high-pressure cavity and the low-pressure cavity are located on the front and back sides of the sensing diaphragm respectively, and the protective shell is provided with a high-pressure inlet and a low-pressure inlet corresponding to the two cavities respectively, the high-pressure inlet is closed by a protective diaphragm one, the protective diaphragm one is of a corrugated structure, the protective shell is fixed with a protective protrusion inside the high-pressure cavity, the surface of the protective protrusion facing the protective diaphragm one is engraved with a plurality of drainage grooves distributed in a radial pattern.

[0006] Further technical solutions are that the silicon cup outputs a resistance signal through a lead.

[0007] Further technical solutions are that the low-pressure inlet is closed by a protective diaphragm two, the protective diaphragm two is of a corrugated structure, the protective shell is fixed with a protective protrusion inside the low-pressure cavity, the surface of the protective protrusion facing the protective diaphragm two is engraved with a plurality of drainage grooves distributed in a radial pattern.

[0008] Further technical solutions are that the sidewall of the protective shell is provided with a liquid storage groove, the liquid storage groove is closed by a protective diaphragm three, and the protective diaphragm three is of a corrugated structure.

[0009] Further, the protective film piece one and the protective film piece two are annular structures, including a fixed ring at the periphery fixed to the protective shell and a wave-shaped plate inside.

[0010] Further, the protective protrusion is a circular ring structure, and the drainage groove is uniformly arranged around the center of the circular ring structure.

[0011] Further, the silicon cup is bonded with a rigid back plate, the rigid back plate is arranged in a spaced manner with the sensing diaphragm, and a pressure channel corresponding to the low-pressure inlet is formed in the rigid back plate.

[0012] Further, the protective shell is provided with an oil injection hole, and the oil injection hole can be closed by a steel ball.

[0013] The working principle and beneficial effects of the present application are as follows:

[0014] 1. The protective film piece one and the protective film piece two are used to protect the pressure sensor from overload, and the double mechanism of external stroke limiting and internal rigid stop is used to protect the fragile sensing diaphragm. When the sensor is subjected to overpressure or pressure impact far exceeding its range, the displacement of the protective film piece one, the protective film piece two and the sensing diaphragm is limited to prevent plastic deformation or rupture due to stress exceeding the yield strength of the material.

[0015] 2. The protective protrusion is provided with a drainage groove for limiting the protective film piece, and the oil path is unobstructed when the protective film piece deforms under normal pressure. When the protective film piece is completely pressed against the plane of the protective protrusion under overload, the silicone oil is completely sealed between the two surfaces, resulting in inaccurate pressure reading or slow rebound of the diaphragm. The radial drainage groove provides an escape and balance path for the silicone oil, and helps the silicone oil flow back quickly when the pressure recovers after overload, helping the diaphragm to separate smoothly from the boss and restore normal work.

[0016] 3. The protective film piece three is used to provide ultimate protection for the pressure sensor. When the pressure is abnormally high and exceeds the design capacity of the above two anti-overload structures, the internal pressure will cause the protective film piece three to rupture or permanently deform. Due to the existence of the liquid storage tank, this will provide a relief space for the internally expanded silicone oil, thereby actively and irreversibly releasing the pressure, avoiding the explosion of the entire sensor shell or the damage of the sensing diaphragm, providing ultimate protection and preventing more serious catastrophic failure. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0018] Figure 1 The present application is a schematic diagram of the overall structure;

[0019] Figure 2 As Figure 1 the enlarged structural schematic view of the middle A part;

[0020] Figure 3 As Figure 1 the enlarged structural schematic view of the middle B part;

[0021] Figure 4 As Figure 1 the enlarged structural schematic view of the middle C part;

[0022] Figure 5 the structural schematic view of the protective film one described in the application;

[0023] Figure 6 the structural schematic view of the protective convex described in the application;

[0024] Figure 7 the structural schematic view of the rigid backboard described in the application.

[0025] In the figure: 100, a silicon cup; 10, a protective shell; 101, a sensing film; 102, a lead wire; 11, a high-pressure cavity; 111, a high-pressure inlet; 12, a low-pressure cavity; 121, a low-pressure inlet; 13, silicone oil; 21, a protective film one; 211, a fixed ring; 212, a wave-shaped plate; 22, a protective film two; 23, a protective film three; 231, a liquid storage groove; 3, a protective convex; 31, a drainage groove; 4, a rigid backboard; 41, a pressure channel; 5, an oil injection hole. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] As Figures 1-7 shown, a pressure sensor packaging structure includes a silicon cup 100 and a protective shell 10, the silicon cup 100 carries a sensing film 101, the silicon cup 100 is a cup-shaped or groove-shaped structure etched from single crystal silicon material through micro-machining technology. It is the base and core mechanical structure of the MEMS pressure sensor chip, and the sensing film 101 carried can convert external pressure into mechanical deformation through elastic deformation, and the thick cup body provides a solid frame for the fragile pressure sensing film, so that the chip can be safely installed.

[0028] The silicon cup 100 divides the protective shell 10 into a high-pressure chamber 11 and a low-pressure chamber 12 and fills them with silicone oil 13. The high-pressure chamber 11 and the low-pressure chamber 12 are located on the front and back sides of the sensing diaphragm 101, respectively. The protective shell 10 has a high-pressure inlet 111 and a low-pressure inlet 121 corresponding to the two chambers, respectively. The high-pressure inlet 111 is sealed by a protective diaphragm 21, which has a corrugated structure. The protective shell 10 has protective protrusions 3 fixed inside the high-pressure chamber 11, which are spaced apart from the protective diaphragm 21. The protective protrusions 3 have several radially distributed drainage grooves 31 engraved on their surface facing the protective diaphragm 21. The silicon cup 100 outputs the resistance signal through the lead wire 102.

[0029] This embodiment provides overload protection for the pressure sensor through a protective diaphragm 21. Specifically, when the protective diaphragm 21 of the high-pressure inlet 111 rapidly bulges into the cavity under enormous pressure, a tiny gap exists between it and the protective protrusion 3. This gap is set to accommodate the maximum safe deformation of the protective diaphragm 21. When this safe limit is reached, the protective diaphragm 21 is stopped from further deformation. Since the filled silicone oil 13 is almost incompressible, pressure transmission is mechanically blocked at this point. This does not affect the internal sensing diaphragm 101.

[0030] Among them, such as Figure 6 As shown, the protective protrusion 3 not only limits the movement of the protective diaphragm, but also has a drainage groove 31. This ensures that the oil passage of the protective diaphragm 21 is unobstructed when it deforms under normal pressure. This prevents the silicone oil 13 from being completely sealed between the two surfaces when the protective diaphragm 21 is fully pressed against the plane of the protective protrusion 3 under overload conditions, which could lead to inaccurate pressure readings or slow diaphragm rebound. The radial drainage groove 31 provides a path for the silicone oil 13 to escape and balance. Furthermore, it helps the silicone oil 13 to flow back quickly when the pressure recovers after an overload, helping the protective diaphragm 21 to smoothly separate from the protrusion and return to normal operation.

[0031] Similarly, the low-pressure inlet 121 is sealed by a protective diaphragm 22, which has a corrugated structure. The protective shell 10 has protective protrusions 3 fixed inside the low-pressure cavity 12, spaced apart from the protective diaphragm 22. Several radially distributed drainage grooves 31 are engraved on the surface of the protective protrusions 3 facing the protective diaphragm 22. The protective diaphragm 22 protects the low-pressure inlet 121, and the specific process is the same as for the high-pressure inlet, so it will not be described again.

[0032] At the same time, such as Figure 4As shown, the application also includes a liquid storage groove 231 on the sidewall of the protective shell 10, which is closed by a protective diaphragm 3, which is a corrugated structure. The protective diaphragm 3 provides ultimate protection for the pressure sensor. When the pressure is abnormally high and exceeds the design capacity of the two anti-overload structures mentioned above, the internal pressure will cause the protective diaphragm 3 to rupture or permanently deform. Due to the existence of the liquid storage groove 231, it will provide a relief space for the internally expanding silicone oil 13, thereby actively and irreversibly releasing the pressure, avoiding the entire sensor shell from bursting or the sensing diaphragm 101 from being damaged, providing ultimate protection and preventing more serious catastrophic failures.

[0033] In addition, on the basis of the above, the silicon cup 100 is bonded with a rigid back plate 4, which is spaced apart from the sensing diaphragm 101, as shown in Figure 7 The rigid back plate 4 has a pressure channel 41 corresponding to the low-pressure inlet 121. The rigid back plate 4 has the same effect as the protective protrusion 3. There is only a small gap between the low-pressure side of the sensing diaphragm 101 and the sensing diaphragm 101. The sensing diaphragm 101 normally bends under pressure difference. The gap ensures its free deformation. When the pressure difference is too large, the sensing diaphragm 101 bends to the limit and directly adheres to the rigid back plate 4. Due to the large contact area, the pressure is evenly distributed, and the sensing diaphragm 101 cannot be further deformed, thereby being protected. At the same time, the pressure channel 41 has two effects. It can accommodate the pressure of the low-pressure inlet 121 to the sensing diaphragm 101, which will not affect the transmission of pressure. Even if a small amount of pressure is transmitted to make the sensing diaphragm 101 bend, it will immediately adhere to the internal rigid glass back plate for final protection. When the external overpressure disappears, the sensing diaphragm 101 restores by relying on its own elasticity and can still be used normally.

[0034] As shown in Figure 5 One embodiment of the protective diaphragm 1, the protective diaphragm 2 and the protective diaphragm 3 is a ring structure, including a fixed ring 211 fixed to the protective shell 10 and an internal corrugated plate 212. Correspondingly, the protective protrusion 3 is a matching circular ring structure, and the drainage groove 31 is uniformly surrounded around the center. The corrugated design is more likely to linearly elastically deform under pressure, can guide the protective diaphragm to bend more evenly and more predictably, thereby ensuring that the pressure and displacement have a good proportional relationship, and a smaller pressure can deform it, improving the sensitivity of the sensor. And the stress distribution is more uniform, can withstand millions of pressure cycles without rupture, as the first ring of pressure transmission, it is easier to transmit external pressure to the internal silicone oil 13 without loss, at the same time, the protective diaphragm also acts as a sealing structure to ensure that the internal silicone oil 13 does not leak and external medium does not invade.

[0035] Specifically, the packaging structure, in use, will fix the silicon cup 100 with isolation diaphragm, rigid backboard 4 and protective shell 10, and various protective diaphragms and other parts at the pressure interface together to form a closed cavity. In a vacuum environment, high-purity silicone oil 13 is injected into the cavity through a small oil injection hole 5. The incompressibility of the silicone oil 13 accurately and non-destructively transmits external pressure to the chip, ensuring that all air bubbles are completely exhausted. The oil injection hole 5 is blocked with a steel ball, and a laser weld is used for permanent sealing. In the wire bonding area 102, soft potting glue is usually filled to further mechanically protect, insulate and prevent moisture from the gold wire and solder joint.

[0036] During operation, external pressure is applied to the outer surface of the protective diaphragm 21. This pressure overcomes the rigidity of the protective diaphragm 21 and the resistance of the internal silicone oil 13, forcing the protective diaphragm 21 to undergo a very small elastic deformation inward. As the isolation diaphragm moves inward, it will try to reduce the total volume of the high-pressure cavity 11, pushing the internal silicone oil 13. This part of the silicone oil 13 has nowhere to go, causing the pressure in the high-pressure cavity 11 system to rise instantaneously. According to Pascal's principle, external pressure will be transmitted synchronously and without loss to every point in the oil-filled cavity, including the front of the sensing diaphragm 101 and the back of the sensing diaphragm 101. The corresponding low-pressure cavity 12 synchronously transmits pressure to the sensing diaphragm 101, thereby forming a pressure difference on both sides. Under the action of this pressure difference, the sensing diaphragm 101 also undergoes a micron-level bending deformation. This deformation causes the resistance value of the pressure-sensitive resistor on it to change, thereby outputting an electrical signal.

[0037] When an overload occurs, the high-pressure inlet 111 protective diaphragm 21 rapidly bulges into the cavity under the pressure. When it is about to exceed the safe deformation limit, it will contact the protective protrusion 3 inside the shell, and the protective diaphragm 21 will be stopped from deforming further. Since the silicone oil 13 is almost incompressible, the pressure transmission is mechanically blocked here, and the same is true at the low-pressure inlet 121. When the pressure is abnormally high and exceeds the design capacity of the two anti-overload structures mentioned above, the internal pressure will cause the protective diaphragm 23 to break or permanently deform. Due to the existence of the liquid storage tank 231, this will provide a space for the internal silicone oil 13 to expand, thereby actively and irreversibly releasing pressure, avoiding the explosion of the entire sensor shell or the damage of the sensing diaphragm 101, providing ultimate protection and preventing more serious catastrophic failures. Even if a small amount of pressure is transmitted to make the sensing diaphragm 101 bend, it will immediately adhere to the internal rigid backboard 4 for final protection. When the external overpressure disappears, the sensing diaphragm 101 relies on its own elasticity to restore to a free state, and the sensor continues to work normally.

[0038] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pressure sensor packaging structure, comprising a silicon cup (100) and a protective shell (10), wherein a sensing diaphragm (101) is mounted on the silicon cup (100), characterized in that: The silicon cup (100) divides the protective shell (10) into a high-pressure chamber (11) and a low-pressure chamber (12) and fills it with silicone oil (13). The high-pressure chamber (11) and the low-pressure chamber (12) are located on the front and back sides of the sensing diaphragm (101), respectively. The protective shell (10) has a high-pressure inlet (111) and a low-pressure inlet (121) corresponding to the two chambers, respectively. The high-pressure inlet (111) is closed by a protective diaphragm (21). The protective diaphragm (21) has a corrugated structure. The protective shell (10) has a protective protrusion (3) fixed inside the high-pressure chamber (11) at intervals from the protective diaphragm (21). The protective protrusion (3) has several radially distributed drainage grooves (31) engraved on the surface of the protective protrusion (3) facing the protective diaphragm (21).

2. The pressure sensor packaging structure according to claim 1, characterized in that, The silicon cup (100) outputs the resistance signal through the lead (102).

3. The pressure sensor packaging structure according to claim 1, characterized in that, The low-pressure inlet (121) is sealed by a protective diaphragm (22), which has a corrugated structure. The protective shell (10) has protective protrusions (3) fixed inside the low-pressure cavity (12) at intervals from the protective diaphragm (22). The protective protrusions (3) facing the protective diaphragm (22) have several radially distributed drainage grooves (31).

4. The pressure sensor packaging structure according to claim 1, characterized in that, The protective shell (10) has a liquid storage tank (231) on its side wall. The liquid storage tank (231) is closed by a protective diaphragm (23), which has a corrugated structure.

5. The pressure sensor packaging structure according to claim 3, characterized in that, Both the first protective diaphragm (21) and the second protective diaphragm (22) are annular structures, including a fixing ring (211) fixed to the outer shell (10) and an inner corrugated plate (212).

6. The pressure sensor packaging structure according to claim 5, characterized in that, The protective protrusion (3) has a circular structure, and the drainage groove (31) is uniformly surrounded around its center.

7. The pressure sensor packaging structure according to claim 1, characterized in that, The silicon cup (100) is bonded with a rigid backplate (4), the rigid backplate (4) is spaced apart from the sensing diaphragm (101), and a pressure channel (41) corresponding to the low pressure inlet (121) is opened on the rigid backplate (4).

8. The pressure sensor packaging structure according to claim 1, characterized in that, The protective shell (10) has an oil injection hole (5) and can be sealed by a steel ball.

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