WO2022104930A1

WO2022104930A1 - Mems sensor

Info

Publication number: WO2022104930A1
Application number: PCT/CN2020/133739
Authority: WO
Inventors: 柏杨; 张睿
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2020-11-17
Filing date: 2020-12-04
Publication date: 2022-05-27
Also published as: CN214299264U

Abstract

A MEMS sensor (100), and a metal lead (40) electrically connecting a MEMS chip (20) and an ASIC chip (30). The metal lead (40) comprises a first solder joint (41) provided on the MEMS chip (20), a first extension portion (43) extending from the first solder joint (41), a first bent portion (44) bent and extending from the first extension portion (43) in a direction away from the MEMS chip (20), a second solder joint (42) arranged on the ASIC chip, a second extension portion (45) extending from the second solder joint (42), a second bent portion (46) bent and extending from the second extension portion (45) in a direction away from the ASIC chip (30), and a third extension portion (47) connecting the first bent portion (44) and the second bent portion (46). The metal lead (40) has a quadrilateral shape, and can both expand and contract at the first bent portion (44) and the second bent portion (46), thereby alleviating deformation caused by thermal stress concentration. The metal lead (40) cannot be easily broken, thereby improving the reliability of the MEMS sensor (100).

Description

A MEMS sensor

technical field

The present application relates to the technical field of acoustics and electricity, and in particular, to a MEMS sensor.

Background technique

The functions of mobile terminals such as smartphones and tablets are becoming more and more powerful, and the application fields of MEMS sensors are becoming more and more extensive, and the requirements for reliability are becoming higher and higher. MEMS (Micro-Electro-Mechanical-System, Micro-Electro-Mechanical-System, MEMS for short) sensors in the prior art, such as MEMS microphones, MEMS ultrasonic transducers, MEMS pressure sensors, etc., have their package structures as shown in Figures 1 to 3 , the MEMS chip 20 and the ASIC chip 30 are attached to the substrate 11, the casing 12 is bonded to the substrate 11 to form a package cavity 10a, the MEMS chip 20 and the ASIC chip 30, and the ASIC chip 30 and the substrate 11 are respectively electrically connected by metal wire bonding, for example , using heat, pressure and ultrasonic energy to make the metal lead 4 and the pad tightly welded. In addition, after metal wire bonding, in order to protect the MEMS chip or ASIC chip from external static electricity, corrosion, etc., or to buffer the stress to ensure the measurement accuracy of the MEMS sensor, a layer of glue is usually covered around the ASIC chip (as shown in Figure 1). ); or cover a layer of glue on the periphery of the MEMS chip (as shown in Figure 2), further, when the ASIC chip is a processor, after covering a layer of glue on the periphery of the MEMS chip, it is usually necessary to encapsulate the ASIC chip with epoxy plastic material wrap (as described in Figure 3), so that the metal leads 4 may pass through materials with different thermal expansion coefficients. In the environmental scenario of thermal cycle such as temperature shock, the materials with different thermal expansion coefficients that the metal lead 4 passes through are quite different. In the MEMS sensor in the prior art, the shape of the metal lead 4 is a triangular arc, and the metal lead 4 is only bent at one point between two solder joints. The metal lead 4 may be subject to material differences in thermal expansion coefficients during environmental tests such as thermal cycling. Additional cyclic thermal stress is generated on the metal lead 4, causing plastic deformation of the metal lead 4, and even causing fatigue disconnection, which has a great potential reliability hazard. Especially when the first welding point of the metal lead 4 is ball welding and the second welding point is wedge welding, the thermal stress is concentrated in the wedge welding fishtail area of the metal lead 4, which is very easy to cause the metal lead 4 to be disconnected. This leads to device failure and reduces the reliability of the MEMS sensor.

technical problem

The purpose of the present application is to provide a MEMS sensor to solve the technical problem of low reliability of the MEMS sensor in the prior art due to the fracture of metal leads.

technical solutions

The technical solution of the present application is as follows: a MEMS sensor, comprising a housing having a packaging cavity, and a MEMS chip and an ASIC chip mounted in the packaging cavity, the housing includes a housing for mounting the MEMS chip and the ASIC chip. A substrate of the ASIC chip and a casing surrounding the substrate to form the packaging cavity, the MEMS sensor further includes metal leads electrically connecting the MEMS chip and the ASIC chip, the metal leads comprising A first solder joint of the MEMS chip, a first extension portion extending from the first solder joint, a first bending portion bent and extended from the first extension portion in a direction away from the MEMS chip, disposed on the A second solder joint of the ASIC chip, a second extension portion extending from the second solder joint, a second bending portion bent and extended from the second extension portion in a direction away from the ASIC chip, and connecting the first A bent portion and a third extension of the second bent portion.

Preferably, the first solder joints are ball solder joints and the second solder joints are wedge solder joints.

Preferably, the first solder joints are wedge solder joints, and the second solder joints are ball solder joints.

Preferably, the MEMS sensor further includes a first glue layer covering the outside of the MEMS chip, and the first extension portion and the first bending portion are covered in the first glue layer.

Preferably, the MEMS sensor further includes a second glue layer wrapped outside the ASIC chip, and the second extension portion and the second bending portion are wrapped in the second glue layer.

Preferably, the MEMS sensor further includes a first glue layer wrapped around the MEMS chip, and the first extension portion and the first bending portion are wrapped in the first glue layer;

The MEMS sensor further includes a second glue layer wrapped outside the ASIC chip, and the second extension portion and the second bending portion are wrapped in the second glue layer;

Wherein, the thermal expansion coefficients of the first glue layer and the second glue layer are different.

Preferably, the height of the side of the first glue layer away from the substrate relative to the substrate on which the MEMS chip is provided is the same as the height of the side of the MEMS chip away from the substrate relative to the substrate. The height difference between the heights of one side of the MEMS chip is greater than 50 μm.

Preferably, the height of the side of the second glue layer away from the substrate relative to the substrate on which the MEMS chip is provided is the same as the height of the side of the ASIC chip away from the substrate relative to the substrate. The height difference between the heights of one side of the MEMS chip is greater than 50 μm.

Preferably, the Young's modulus of the first glue layer is less than 2Mpa.

Preferably, the Young's modulus of the second glue layer is less than 2Mpa.

beneficial effect

The beneficial effect of the present application is that in the MEMS sensor of the present application, the metal wire electrically connecting the MEMS chip and the ASIC chip includes a first solder joint disposed on the MEMS chip, and a first extension portion extending from the first solder joint. , a first bent portion bent and extended from the first extension portion to a direction away from the MEMS chip, a second solder joint disposed on the ASIC chip, and a second extension portion extended from the second solder joint , a second bending portion extending from the second extending portion to a direction away from the ASIC chip, and a third extending portion connecting the first bending portion and the second bending portion; by the above method , The shape of the metal lead has been improved. The shape of the metal lead is quadrilateral, which can be stretched at the first bending part and the second bending part, which alleviates the deformation caused by thermal stress concentration, and the metal lead is not easy to break. reliability of MEMS sensors.

Description of drawings

1 is a schematic structural diagram of a first MEMS sensor in the prior art;

2 is a schematic structural diagram of a second type of MEMS sensor in the prior art;

3 is a schematic structural diagram of a third MEMS sensor in the prior art;

4 is a schematic structural diagram of a MEMS sensor according to an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a MEMS sensor in a first preferred manner in an embodiment of the application;

6 is a schematic structural diagram of a MEMS sensor in a second preferred manner in an embodiment of the application;

FIG. 7 is a schematic structural diagram of a MEMS sensor in a third preferred manner in an embodiment of the present application.

Embodiments of the present invention

In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

In the following, many aspects of the present application will be better understood with reference to the accompanying drawings. Features in the figures are not necessarily drawn to scale. Instead, emphasis is placed on clearly illustrating components of the present application. Furthermore, like reference numerals indicate corresponding parts throughout the several views of the drawings.

The words "exemplary" or "illustrative" as used herein mean serving as an example, instance, or illustration. Any implementation described herein as "exemplary" or "illustrative" is not necessarily to be construed as preferred or advantageous over other implementations. All embodiments described below are exemplary embodiments provided to enable those skilled in the art to make and use examples of the disclosure and are not intended to limit the scope of the disclosure, which is defined by The claims are limited. In other instances, well-known features and methods have been described in detail so as not to obscure the application. For the purposes of this description, the terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal" and derivatives thereof will be oriented as in FIG. 1 of utility models. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, utility summary or the following detailed description. It should also be appreciated that the specific apparatus and processes illustrated in the drawings and described in the following specification are simple exemplary embodiments of the inventive concept defined in the appended claims. Therefore, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be construed as limiting unless the claims expressly state otherwise.

The embodiment of the present application provides a MEMS sensor 100. Please refer to FIG. 4. As shown in FIG. 4, the MEMS sensor 100 includes a housing 10 having a packaging cavity 10a, a MEMS chip 20 and an ASIC chip 30 installed in the packaging cavity 10a. and the metal leads 40 electrically connecting the MEMS chip 20 and the ASIC chip 30 .

Wherein, the casing 10 includes a substrate 11 for mounting the MEMS chip 20 and the ASIC chip 30 and a casing 12 surrounding the substrate 11 to form the packaging cavity 10a.

The metal lead 40 includes a first pad 41 on the MEMS chip 20 , a second pad 42 on the ASIC chip, and a first extension 43 extending from the first pad 41 . , a first bending portion 44 extending from the first extending portion 43 to a direction away from the MEMS chip 20 , a second extending portion 45 extending from the second solder joint 42 , extending from the second The portion 45 is a second bending portion 46 extending away from the ASIC chip 30 and a third extending portion 47 connecting the first bending portion 44 and the second bending portion 46 . Further, the first solder joint 41 is a ball solder joint, and the second solder joint 42 is a wedge solder joint; or, the first solder joint 41 is a wedge solder joint, and the second solder joint 42 is a ball joint solder joints.

In this embodiment, the shape of the metal lead 40 is a quadrangle, and both the first bending part 44 and the second bending part 46 can be stretched, which relieves the deformation caused by the thermal stress concentration, and the metal lead 40 is not easy to be broken. The reliability of the MEMS sensor 100 is improved.

In a first optional implementation manner, as shown in FIG. 5 , the MEMS sensor 100 of this embodiment further includes a first glue layer 50 covering the MEMS chip 20 , and the first extension portion 43 and the first bending portion 44 are both covered in the first glue layer 50 . When the metal lead 40 is additionally thermally stressed due to the thermal expansion of the first glue layer 50 , the stress concentration can be effectively relieved by the expansion and contraction of the first bending portion 44 , and the metal lead 40 is not easily broken.

Further, the height of the side of the first glue layer 50 away from the substrate 11 is h1 relative to the side of the substrate 11 where the MEMS chip 20 is provided, and the MEMS chip 20 is away from a side of the substrate 11 . The height of the side with the MEMS chip 20 relative to the substrate 11 is h2, and the height difference between h1 and h2 is greater than 50 μm.

Further, the Young's modulus of the first glue layer 50 is less than 2Mpa, and the texture of the first glue layer 50 is relatively soft. The first bending portion 44 in the first glue layer 50 is more easily stretched, which further relieves the stress concentration of the metal lead 40 . The material of the first glue layer 50 may be silica gel.

In a second optional implementation manner, please refer to FIG. 6 , the MEMS sensor 100 of this embodiment further includes a second glue layer 60 wrapped around the ASIC chip 30 , and the second extension portion 45 and the second bending portion 46 is wrapped in the second glue layer 60 . When the metal lead 40 is additionally thermally stressed due to the thermal expansion of the second glue layer 60 , the stress concentration can be effectively relieved by the expansion and contraction of the second bending portion 46 , and the metal lead 40 is not easily broken.

Further, the height of the side of the second glue layer 60 away from the substrate 11 is h3 relative to the side of the substrate 11 where the MEMS chip 20 is provided, and the ASIC chip 30 is away from a side of the substrate 11 . The height of the side with the MEMS chip 20 relative to the substrate 11 is h4, and the height difference between h3 and h4 is greater than 50 μm.

Further, the Young's modulus of the second glue layer 60 is less than 2Mpa, and the texture of the second glue layer 60 is relatively soft. The second bending portion 46 in the second glue layer 60 is easier to expand and contract, which further relieves the stress concentration of the metal lead 40 . The material of the second glue layer 60 may be silica gel.

In a third optional implementation manner, the MEMS sensor 100 of this embodiment also includes a first glue layer 50 covering the outside of the MEMS chip 20 and a second glue layer covering the outside of the ASIC chip 30 at the same time layer 60, the first extension portion 43 and the first bending portion 44 are both covered in the first glue layer 50, and the second extension portion 45 and the second bending portion 46 are covered In the second glue layer 60 , and the thermal expansion coefficients of the first glue layer 50 and the second glue layer 60 are different. In this embodiment, the metal leads 40 pass through the first glue layer 50 and the second glue layer 60 with different thermal expansion coefficients at the same time. The difference causes additional thermal stress to the metal lead 40 . The expansion and contraction of the first bending portion 44 and the second bending portion 46 can effectively relieve stress concentration, and the metal lead 40 is not easily broken.

Further, the Young's modulus of the first glue layer 50 is less than 2Mpa, and the Young's modulus of the second glue layer 60 is less than 2Mpa. In the thermal cycle environment, since the Young's modulus of the first glue layer 50 and the second glue layer 60 are small, the first bending part 44 wrapped in the first glue layer 50 and the second glue layer The second bending portion 46 in the 60 is easier to expand and contract, which further relieves the stress concentration of the metal lead 40 .

The above are only the embodiments of the present application. It should be pointed out that for those of ordinary skill in the art, improvements can be made without departing from the creative concept of the present application, but these belong to the present application. scope of protection.

Claims

1. A MEMS sensor, comprising a housing having a packaging cavity and a MEMS chip and an ASIC chip mounted in the packaging cavity, the housing comprising a substrate for mounting the MEMS chip and the ASIC chip, and The casing surrounding the substrate to form the packaging cavity is characterized in that the MEMS sensor further includes a metal lead electrically connecting the MEMS chip and the ASIC chip, and the metal lead includes a metal lead provided on the MEMS chip. a first solder joint of the chip, a first extension part extending from the first solder joint, a first bending part bent and extended from the first extension part in a direction away from the MEMS chip, arranged on the ASIC A second solder joint of the chip, a second extension portion extending from the second solder joint, a second bending portion bent and extended from the second extension portion in a direction away from the ASIC chip, and connecting the first A bent portion and a third extension of the second bent portion.

2. The MEMS sensor of claim 1, wherein the first solder joint is a ball solder joint, and the second solder joint is a wedge solder joint.

3. The MEMS sensor of claim 1, wherein the first solder joint is a wedge solder joint, and the second solder joint is a ball solder joint.

4. The MEMS sensor according to claim 1, wherein the MEMS sensor further comprises a first glue layer covering the outside of the MEMS chip, the first extension part and the first bending part wrapped in the first glue layer.

5. The MEMS sensor according to claim 1, wherein the MEMS sensor further comprises a second glue layer coated on the outside of the ASIC chip, the second extension part and the second bending part wrapped in the second glue layer.

6. The MEMS sensor according to claim 1, wherein the MEMS sensor further comprises a first glue layer covering the outside of the MEMS chip, the first extension part and the first bending part wrapped in the first glue layer;

7. The MEMS sensor according to claim 4 or 6, characterized in that, the height of the side of the first glue layer away from the substrate relative to the side of the substrate on which the MEMS chip is provided is the same as the height of the MEMS The height difference between the side of the chip away from the substrate and the height of the side of the substrate on which the MEMS chip is provided is greater than 50 μm.

8. The MEMS sensor according to claim 5 or 6, wherein a side of the second glue layer away from the substrate has a height relative to the side of the substrate on which the MEMS chip is provided with the ASIC The height difference between the side of the chip away from the substrate and the height of the side of the substrate on which the MEMS chip is provided is greater than 50 μm.

9. The MEMS sensor according to claim 4 or 6, wherein the Young's modulus of the first glue layer is less than 2Mpa.

10. The MEMS sensor according to claim 5 or 6, wherein the Young's modulus of the second glue layer is less than 2Mpa.