Assembly structure of pressure sensor and pressure sensor

Abstract

The utility model relates to the technical field of pressure detection, and discloses an assembly structure of a pressure sensor and the pressure sensor, and the assembly structure comprises a PCB and a substrate. The PCB is provided with a first through hole, the top surface of the PCB is provided with a bonding pad at the periphery of the first through hole, and the inner diameter of the bonding pad is the same as the aperture of the first through hole; a second through hole is formed in the substrate, the substrate is located on the top surface of the PCB, and the aperture of the second through hole is smaller than that of the first through hole; when in use, the diameter of the second through hole is smaller than that of the first through hole by the assembly structure, so that the scaling powder flying to the sensitive surface of the MEMS chip is blocked by the second through hole of the substrate during SMT (surface mount technology) welding, and the probability that the MEMS chip is polluted is reduced; in addition, a metal coating is not arranged on the inner wall of the first through hole, so that soldering tin cannot climb into the hole wall of the first through hole during SMT welding; and finally, the diameter of the first through hole is larger than that of the second through hole, so that the possibility that the first through hole is blocked by tin slag can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of pressure detection, in particular to an assembly structure of a pressure sensor and a pressure sensor. Background Art

[0002] Pressure sensors are required for pressure detection in the fields of monitoring and control of hydraulic, pneumatic and hydraulic systems in the industrial field, blood vessel and nerve pressure detection in the medical field, and tire pressure detection in the automobile field. The pressure sensor includes a PCB board and a substrate on the PCB board, a ventilating channel and a MEMS chip are provided on the top surface of the substrate, a through hole with the same width as the ventilating channel is provided on the PCB board, a metal plating layer is provided on the inner wall of the through hole, and a ring pad is provided on the PCB board at one end of the through hole close to the substrate, and the inner diameter of the ring pad is the same as the width of the through hole and the ventilating channel.

[0003] At present, in the assembly design of MEMS pressure sensor modules, the following two methods are usually used to achieve the sealing between MEMS and substrate, as follows:

[0004] Method 1: Use glue to connect the MEMS and the substrate to form a seal. However, in actual use, this method has the following defects: the consistency and stability of the glue process seal are poor, and it cannot be used for the production of large-range pressure sensors.

[0005] Method 2: The MEMS sensor module is soldered to the PCB board through the circular pad through the reflow soldering process to achieve air path sealing. The reflow soldering process has better consistency and stability. Compared with glue sealing, it can withstand higher pressure and has a wider range of applications. However, the existing reflow soldering assembly structure has the following problems in actual manufacturing:

[0006] 1. During the welding process, the flux in the solder paste will produce a "burst" phenomenon due to the rapid rise in temperature, that is, the flux will splash in different directions. Since the pad position design lacks a blocking structure, part of the flux will fly to the sensing film of the MEMS chip through the air permeable channel of the substrate, affecting the sensitivity of the sensing film, causing the product to have an output drift problem, affecting the accuracy of high-precision pressure signal detection;

[0007] Second, because the through-holes of the PCB board are metal-plated and connected to the pads, solder can easily creep into the through-holes, which is called through-hole tin creeping. If this phenomenon is serious, it will cause pore blockage, resulting in sensor failure, thereby increasing manufacturing costs. Utility Model Content

[0008] In view of the shortcomings of the background technology, the utility model provides an assembly structure of a pressure sensor and a pressure sensor. The technical problem to be solved is that during reflow soldering, the PCB board and substrate of the existing pressure sensor have the phenomenon that flux flies onto the sensing film of the MEMS chip and tin creeps in the through hole of the PCB board, which affects the use of the pressure sensor.

[0009] To solve the above technical problems, in a first aspect, the utility model provides the following technical solutions: an assembly structure of a pressure sensor, comprising a PCB board and a substrate;

[0010] The PCB board is provided with a first through hole for transmitting pressure, and the top surface of the PCB board is provided with an annular pad outside the first through hole, and the inner diameter of the pad is the same as the aperture of the first through hole;

[0011] The substrate is provided with a second through hole for transmitting pressure. The substrate is located on the top surface of the PCB board, and the aperture of the second through hole is smaller than the aperture of the first through hole.

[0012] In a certain embodiment of the first aspect, an upward extension line of a line segment connecting a lower opening of the second through hole and an upper opening of the first through hole is below the upper opening of the second through hole.

[0013] In a certain embodiment of the first aspect, a vertical center line of the first through hole and a vertical center line of the second through hole are on the same straight line.

[0014] In a second aspect, the utility model further provides a pressure sensor, comprising the above-mentioned assembly structure of a pressure sensor, wherein the substrate is soldered on the PCB board through the soldering pad.

[0015] In a certain embodiment of the second aspect, a MEMS chip is provided on the top surface of the substrate at the periphery of the second through hole, the sensitive surface of the MEMS chip faces the second through hole, and the contact surface between the MEMS chip and the substrate is sealed.

[0016] In a certain implementation manner of the second aspect, the top surface of the substrate is further provided with an upper cover, and the MEMS chip and the ASIC chip are both inside the upper cover.

[0017] In a certain embodiment of the second aspect, a ventilation hole is opened on the top surface of the upper cover, and the ventilation hole is used to connect the outside with the inside of the upper cover.

[0018] In a certain implementation manner of the second aspect, a signal processing circuit is provided on the top surface of the PCB board, and the signal processing circuit is used to process the output signal of the MEMS chip.

[0019] In a certain implementation manner of the second aspect, the utility model further includes a housing, and the PCB board is installed in the housing.

[0020] Compared with the prior art, the utility model has the following beneficial effects: for the assembly structure of the utility model, by making the diameter of the second through hole smaller than the diameter of the first through hole, when performing SMT process welding, the solder flux flying toward the sensitive surface of the MEMS chip will be blocked by the second through hole of the substrate, thereby reducing the probability of the MEMS chip being contaminated during SMT process welding; in addition, by not providing a metal plating layer on the inner wall of the first through hole, the solder can not climb into the hole wall of the first through hole during SMT welding; finally, by making the diameter of the first through hole larger than the diameter of the second through hole, the possibility of tin slag blocking the first through hole can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the assembly structure in Example 1;

[0022] Figure 2 It is a schematic diagram of the MEMS chip in the first embodiment on the assembly structure;

[0023] Figure 3 It is a schematic diagram of the structure of the pressure sensor in the second embodiment. DETAILED DESCRIPTION

[0024] Now the utility model is further described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the utility model in a schematic manner, and therefore only show the components related to the utility model.

[0025] like Figure 1 As shown, an assembly structure of a pressure sensor includes a PCB board 1 and a substrate 3;

[0026] A first through hole 10 for transmitting pressure is provided on the PCB board 1, and a ring-shaped pad 2 is provided on the top surface of the PCB board 1 outside the first through hole 10, and the inner diameter of the pad 2 is the same as the aperture of the first through hole 10;

[0027] A second through hole 30 for transmitting pressure is provided on the substrate 3 . The substrate 3 is located on the top surface of the PCB board 1 , and the aperture of the second through hole 30 is smaller than the aperture of the first through hole 10 .

[0028] Specifically, in Figure 1 In the embodiment, the vertical center line of the first through hole 10 and the vertical center line of the second through hole 30 are on the same straight line.

[0029] exist Figure 1In the figure, a is the thickness of the substrate 3, b is the thickness of the pad 2, c is the ring width of the pad 2, d is the thickness of the PCB board, e1 is the diameter of the first through hole 10, and f is the diameter of the second through hole 30.

[0030] Specifically, in Figure 1 In the embodiment, the diameter e1 of the first through hole 10 and the diameter of the second through hole 30 need to be set so that the upward extension line of the line segment connecting the lower opening of the second through hole 30 and the upper opening of the first through hole 10 is below the upper opening of the second through hole 30 .

[0031] In this embodiment, the MEMS chip Figure 1 The structural diagram of the structure shown is as follows Figure 2 As shown, in actual use, by making the diameter of the second through hole 30 smaller than the diameter of the first through hole 10, when performing SMT process welding, the flux flying to the sensitive surface of the MEMS chip 4 will be blocked by the second through hole 30 of the substrate 3, thereby reducing the probability of the MEMS chip 4 being contaminated during SMT process welding; in addition, by not providing a metal plating layer on the inner wall of the first through hole 10, the solder cannot climb into the hole wall of the first through hole 10 during SMT welding; finally, by making the diameter of the first through hole 10 larger than the diameter of the second through hole 30, the possibility of tin slag blocking the first through hole 10 can be reduced.

[0032] Embodiment 2

[0033] like Figure 3 As shown, this embodiment provides a pressure sensor, including an assembly structure of a pressure sensor in Embodiment 1, wherein a substrate 3 is soldered on a PCB board 1 through a solder pad 2 .

[0034] Specifically, in this embodiment, a MEMS chip 4 is disposed on the top surface of the substrate 3 at the periphery of the second through hole 30 , the sensitive surface of the MEMS chip 4 faces the second through hole 30 , and the contact surface between the MEMS chip 4 and the substrate 1 is sealed.

[0035] In actual use, the pressure source to be detected can reach the sensitive surface of the MEMS chip 4 from the first through hole 10 and the second through hole 30 for detection.

[0036] In addition, in this embodiment, an upper cover 6 is further provided on the top surface of the substrate 3 , and the MEMS chip 5 and the ASIC chip 4 are both inside the upper cover 6 .

[0037] In order to realize the gauge pressure detection, a vent hole 60 is opened on the top surface of the upper cover 6 , and the vent hole 60 is used to connect the outside with the inside of the upper cover 6 .

[0038] Specifically, in this embodiment, a signal processing circuit 7 is provided on the top surface of the PCB board 1, and the signal processing circuit 7 is used to process the output signal of the MEMS chip to obtain an output signal that ultimately represents the detection pressure, wherein the output signal can be either a voltage or a current.

[0039] Specifically, in this embodiment, the utility model further includes a housing, and the PCB board 1 is installed in the housing.

[0040] The above is based on the disclosure of the utility model. Through the above description, relevant staff can make various changes and modifications without deviating from the technical concept of the utility model. The technical scope of the utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An assembly structure of a pressure sensor, characterized in that: It comprises a PCB board (1) and a substrate (3); The PCB board (1) is provided with a first through hole (10) for transmitting pressure, and the top surface of the PCB board (1) is provided with an annular solder pad (2) outside the first through hole (10), and the inner diameter of the solder pad (2) is the same as the aperture of the first through hole (10); The substrate (3) is provided with a second through hole (30) for transmitting pressure, the substrate (3) is located on the top surface of the PCB board (1), and the aperture of the second through hole (30) is smaller than the aperture of the first through hole (10).

2. The assembly structure of a pressure sensor according to claim 1, characterized in that: An upward extension line of a line segment connecting a lower opening of the second through hole (30) and an upper opening of the first through hole (10) is below the upper opening of the second through hole (30).

3. The assembly structure of a pressure sensor according to claim 1, characterized in that: The vertical center line of the first through hole (10) and the vertical center line of the second through hole (30) are on the same straight line.

4. A pressure sensor, characterized in that: An assembly structure of a pressure sensor comprising the structure described in any one of claims 1 to 3, wherein the substrate (3) is soldered on the PCB board (1) via the soldering pad (2).

5. A pressure sensor according to claim 4, characterized in that: A MEMS chip (4) is provided on the top surface of the substrate (3) at the periphery of the second through hole (30), the sensitive surface of the MEMS chip (4) faces the second through hole (30), and the contact surface between the MEMS chip (4) and the substrate (3) is sealed.

6. A pressure sensor according to claim 5, characterized in that: The top surface of the substrate (3) is also provided with an upper cover (6), and the MEMS chip (4) and the ASIC chip (5) are both inside the upper cover (6).

7. A pressure sensor according to claim 6, characterized in that: The top surface of the upper cover (6) is provided with an air vent (60), and the air vent (60) is used to connect the outside with the inside of the upper cover (6).

8. A pressure sensor according to claim 7, characterized in that: A signal processing circuit (7) is provided on the top surface of the PCB board (1), and the signal processing circuit (7) is used to process the output signal of the MEMS chip (4).

9. A pressure sensor according to any one of claims 2 to 8, characterized in that: It also comprises a housing, in which the PCB board (1) is installed.

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