Transmit-receive split type ultrasonic sensor module

Abstract

This invention provides a transceiver-type ultrasonic sensor module, including a substrate; a housing, which is sealed to the substrate and has a transmitting sound hole and a receiving sound hole; a MEMS transmitting chip, which is located inside the transmitting cavity and has its back side fixed to the substrate, and is electrically connected to the substrate; a MEMS receiving chip, which is located inside the receiving cavity; and welding protrusions, which are provided on the surface of the substrate near the MEMS receiving chip for electrical connection between the substrate and the MEMS receiving chip; and a sealed cavity defined by the space between the substrate and the MEMS receiving chip. This invention, through the housing having a transmitting cavity and a receiving cavity, and by forming transmitting and receiving sound holes on the housing corresponding to the transmitting and receiving directions of the two cavities, a Helmholtz resonant cavity is formed to enhance the sound pressure level of the transmitting chip and to form a receiving resonant cavity, thereby enhancing the sensitivity of the receiving chip.

Description

Technical Field

[0001] This specification relates to the field of sensor technology, and more particularly to a transceiver-type ultrasonic sensor module. Background Technology

[0002] A transceiver-separated ultrasonic sensor module refers to a module where the sensors transmitting and receiving ultrasonic signals are separate. Using this type of transceiver-separated ultrasonic sensor module, the blind zone time can be reduced to almost zero. Currently, transceiver-separated ultrasonic sensor modules have a wide range of applications, such as ranging, obstacle avoidance, and level detection.

[0003] Currently available discrete ultrasonic sensor modules are mostly piezoelectric ceramic type, which has the following disadvantages:

[0004] Due to their large size, the dimensions of a single ultrasonic probe are generally φ10mm*20mm (including the pin height). With the addition of the substrate and some simple circuits, the size of the entire discrete ultrasonic sensor module generally exceeds 30*20*20mm, which greatly limits the application scenarios of discrete ultrasonic sensor modules.

[0005] Assembly is difficult because ultrasonic probes are pin-type and incompatible with SMT processes, requiring individual assembly and resulting in low efficiency. Furthermore, this also means that separate ultrasonic sensor modules are incompatible with SMT processes, leading to low assembly efficiency. Therefore, this application proposes a separate transceiver ultrasonic sensor module to solve the aforementioned problems. Summary of the Invention

[0006] The present invention aims to solve one of the problems mentioned in the background art. The purpose of one or more embodiments of this specification is to propose a transceiver-type ultrasonic sensor module, which uses MEMS chips processed by semiconductor technology and module packaging manufacturing by automated packaging technology, and has the advantages of small size and easy assembly while ensuring high sensitivity.

[0007] Based on the above objectives, one or more embodiments of this specification provide a transceiver-type ultrasonic sensor module, comprising: a substrate; a housing, the housing being sealed to the substrate, the housing having two mutually sealed transmitting cavities and receiving cavities for housing, the housing having transmitting holes corresponding to the positions of the transmitting cavities, and the housing having receiving holes corresponding to the positions of the receiving cavities; a MEMS transmitting chip, the MEMS transmitting chip having opposing front and back sides, the back side having a back cavity, the MEMS transmitting chip being located inside the transmitting cavities, and the back side of the MEMS transmitting chip being attached and fixed to the substrate, the MEMS transmitting chip being electrically connected to the substrate; a MEMS receiving chip, the MEMS receiving chip having opposing front and back sides, the MEMS receiving chip being located inside the receiving cavity; a welding protrusion, the surface of the substrate near the MEMS receiving chip being provided with a welding protrusion, the welding protrusion being used for electrical connection between the substrate and the MEMS receiving chip; the space between the substrate and the MEMS receiving chip defining a sealed cavity.

[0008] In some embodiments, the height of the MEMS receiving chip is higher than the height of the MEMS transmitting chip.

[0009] In some embodiments, the MEMS transmitter chip is electrically connected to the substrate via gold wires.

[0010] In some specific embodiments, the back side of the MEMS emitting chip is packaged with the substrate by bonding, and the back side of the MEMS emitting chip is fixedly connected to the substrate by a hard adhesive patch.

[0011] In some specific embodiments, the front side of the MEMS receiver chip is provided with solder pads, and the solder protrusions are electrically connected to the solder pads.

[0012] In some embodiments, the space between the substrate and the MEMS receiving chip is defined as a sealed cavity by potting compound.

[0013] In some embodiments, the thickness of the sealing cavity is the same as the height of the weld protrusion.

[0014] In some embodiments, the back side of the MEMS receiver chip is sealed to the top wall of the receiver cavity of the housing using adhesive.

[0015] As can be seen from the above, the present invention has the following beneficial effects:

[0016] The present invention uses a housing with a transmitting cavity and a receiving cavity. The receiving chip is set up in an inverted manner and is higher than the transmitting chip. This prevents the air coupling vibration of the transmitting chip from affecting the receiving chip. In addition, after the receiving chip is inverted, the contact area between it and the substrate is small, which reduces the vibration impact transmitted from the transmitting chip to the receiving chip through the substrate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in one or more embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one or more embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the external structure of the ultrasonic sensor module in an embodiment of the present invention;

[0019] Figure 2 This is an exploded view of the ultrasonic sensor module in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the internal structure of the ultrasonic sensor module in an embodiment of the present invention;

[0021] Figure 4 This is an internal cross-sectional view of the receiving cavity in the ultrasonic sensor module of this invention.

[0022] Figure 5 This is a schematic diagram of the substrate structure in the ultrasonic sensor module of this invention.

[0023] Figure 6 This is a cross-sectional view of the ultrasonic sensor module in an embodiment of the present invention;

[0024] Figures 7-8 This is a schematic diagram illustrating the impact of vibration transmission in existing technologies.

[0025] In the attached diagram, the following are the reference numerals: 1. Outer shell; 2. Gold wire; 3. MEMS transmitter chip; 4. Substrate; 5. Solder protrusion; 6. Encapsulating adhesive; 7. MEMS receiver chip; 8. Adhesive for shell mounting; a. Transmitting sound hole; b. Receiving cavity; c. Receiving sound hole; d. Sealed cavity; e. Transmitting cavity. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0027] The following is based on Figures 1-6This section describes the specific structure of the transceiver-separated ultrasonic sensor module in the embodiments of the present invention.

[0028] Please see Figures 1-6 According to the embodiments of the present invention, the transceiver-separated ultrasonic sensor module includes a substrate 4, a housing 1, a MEMS transmitting chip 3, a MEMS receiving chip 7, a connector 5, and potting compound 6.

[0029] The outer casing 1 is sealed to the substrate 4. The outer casing 1 effectively prevents vibrations from the transmitting chip coupled to the receiving chip via air. Inside the outer casing 1 are two mutually sealed cavities: a transmitting cavity e and a receiving cavity b. The MEMS transmitting chip 3 is located inside the transmitting cavity e, and has a front and a back facing. The MEMS receiving chip 7 is located inside the receiving cavity b, and also has a front and a back facing. The outer casing 1 has a transmitting sound hole a corresponding to the position of the transmitting cavity e. The diameter of the transmitting sound hole a is preferably 0.6-1.0 mm. The cavity of the transmitting chip, combined with the size of the transmitting sound hole a, forms a Helmholtz resonant cavity to enhance the transmitted sound pressure level. The Helmholtz resonant cavity is essentially a narrowband filter, amplifying signals within its frequency band and suppressing signals outside its band. The resonant frequency of the cavity can be calculated using the following formula:

[0030]

[0031] In the formula: f is the cavity resonant frequency; c is the speed of sound in air; V is the volume of the front cavity; S is the area of ​​the sound hole; t is the wall thickness of the sound hole; a is the radius of the sound hole; λ is the correction coefficient.

[0032] The outer shell 1 has a receiving sound hole c at the position corresponding to the receiving cavity b. The diameter of the receiving sound hole c is preferably 0.3-0.6mm. The diameter of the receiving sound hole c is smaller than the diameter of the transmitting sound hole a. The MEMS receiving chip 7 forms a Helmholtz resonant cavity for receiving through the size of the chip back cavity and the sound outlet hole, which is used to enhance the receiving sensitivity.

[0033] The MEMS emitting chip 3 has a front and a back side, with a cavity on the back side. The MEMS emitting chip 3 is located inside the emitting cavity e, and its back side is bonded and fixed to the substrate 4, with electrical communication between them. Optionally, the MEMS emitting chip 3 is electrically connected to the substrate 4 via gold wires 2. Optionally, the MEMS emitting chip 3 is packaged to the substrate 4 by bonding, which ensures that the emitted sound pressure level of the MEMS emitting chip 3 is not suppressed. Optionally, the MEMS emitting chip 3 is connected to the substrate 4 via a rigid adhesive patch, which allows the sound pressure level of the diaphragm cavity of the MEMS emitting chip 3 to be reflected and superimposed, thus enhancing the emitted sound pressure level to some extent. Finally, through the Helmholtz resonator described above, the emitted sound pressure level can be further amplified.

[0034] The MEMS receiver chip 7 has a front and a back side, and is located inside the receiving cavity b. A welding protrusion 5 is provided on the surface of the substrate 1 near the MEMS receiver chip 7. The welding protrusion 5 is used for electrical connection between the substrate 4 and the MEMS receiver chip 7, reducing the contact area between the receiver chip and the substrate 4. This significantly reduces the vibration transmitted from the MEMS transmitter chip 3 to the MEMS receiver chip 7 through the substrate 4, achieving the effect of suppressing dead zones. Figure 7 As shown. Optionally, the solder bump 5 is a solder ball with a diameter of 50-150μm. Optionally, the solder bump 5 is made of conductive adhesive or conductive silver paste. Optionally, a solder pad is provided on the front side of the MEMS receiving chip 7, and the solder bump 5 is electrically connected to the solder pad. Optionally, the thickness of the sealing cavity d is the same as the height of the solder bump 5. The space between the substrate 4 and the MEMS receiving chip 7 defines the sealing cavity d. Optionally, the space between the substrate 4 and the MEMS receiving chip 7 is defined by potting compound 6 to form the sealing cavity d, and the sealing cavity d applies air damping to the diaphragm of the MEMS receiving chip 7, thereby reducing the dead zone time of the entire transceiver-type ultrasonic sensor module.

[0035] In some specific embodiments, the height of the MEMS receiving chip 7 is higher than the height of the MEMS transmitting chip 3. Through the housing 1, the height difference between the MEMS transmitting chip 3 and the MEMS receiving chip 7 can reduce the vibration of the MEMS transmitting chip 3 coupled to the MEMS receiving chip 7 via air coupling. Figure 8 As shown.

[0036] In some specific embodiments, the back of the MEMS receiver chip 7 is sealed to the top wall of the receiver cavity b of the outer shell 1 by adhesive 8, which increases the stability of the MEMS receiver chip 7.

[0037] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the scope of protection of this disclosure.

Claims

1. A transceiver-type ultrasonic sensor module, characterized in that, include: substrate(4); A housing (1) is sealed to a substrate (4). The housing (1) has two mutually sealed transmitting cavities (e) and receiving cavities (b) for housing. A transmitting sound hole (a) is provided in the housing (1) corresponding to the position of the transmitting cavity (e), and a receiving sound hole (c) is provided in the housing (1) corresponding to the position of the receiving cavity (b). MEMS emitting chip (3), the MEMS emitting chip (3) has a front and a back side, the back side has a back cavity, the MEMS emitting chip (3) is located inside the emitting cavity (e), and the back side of the MEMS emitting chip (3) is attached and fixed to the substrate (4), the MEMS emitting chip (3) and the substrate (4) are electrically connected. MEMS receiver chip (7), the MEMS receiver chip (7) has a front and a back facing each other, and the MEMS receiver chip (7) is located inside the receiver cavity (b); Welding protrusion (5): The substrate (4) is provided with welding protrusion (5) on the surface near the MEMS receiver chip (7). The welding protrusion (5) is used for electrical connection between the substrate (4) and the MEMS receiver chip (7). The space between the substrate (4) and the MEMS receiving chip (7) is defined by potting compound (6) to form a sealed cavity (d). The height of the MEMS receiver chip (7) is higher than the height of the MEMS transmitter chip (3).

2. The transceiver-type ultrasonic sensor module according to claim 1, characterized in that, The MEMS transmitter chip (3) is electrically connected to the substrate (4) via gold wire (2).

3. The transceiver-type ultrasonic sensor module according to claim 2, characterized in that, The back side of the MEMS emitting chip (3) is packaged with the substrate (4) by bonding, and the back side of the MEMS emitting chip (3) is fixedly connected to the substrate (4) by hard adhesive patch.

4. The transceiver-separated ultrasonic sensor module according to claim 2, characterized in that, The front side of the MEMS receiver chip (7) is provided with a solder pad, and the solder protrusion (5) is electrically connected to the solder pad.

5. The transceiver-type ultrasonic sensor module according to claim 1, characterized in that, The thickness of the sealing cavity (d) is the same as the height of the welding protrusion (5).

6. The transceiver-type ultrasonic sensor module according to claim 1, characterized in that, The back of the MEMS receiver chip (7) is sealed to the top wall of the receiver cavity (b) of the outer shell (1) by means of adhesive (8).

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