CN211770287U

CN211770287U - Packaging structure of inertial sensor

Info

Publication number: CN211770287U
Application number: CN201922314462.1U
Authority: CN
Inventors: 邓登峰
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-10-27
Anticipated expiration: 2029-12-20

Abstract

Disclosed is a package structure of an inertial sensor, including: a substrate having opposing first and second surfaces; a first die attached to a first surface of a substrate; a second die attached to the first die; a frame structure fixed on the first surface of the substrate such that the first die and the second die are located in the frame structure; and a plastic package body located on the first surface of the substrate and covering the first die and the second die and the frame structure. The utility model provides an among inertial sensor's the packaging structure, adopt to fix the frame construction on the first surface of base plate, lie in frame construction with first tube core and second tube core, because frame construction's high modulus absorbs the stress to the production of sensor tube core among the encapsulation process, makes the sensor tube core avoid or alleviate stress and deformation that external stress leads to.

Description

Packaging structure of inertial sensor

Technical Field

The utility model relates to a MEMS inertial sensor encapsulates technical field, in particular to inertial sensor's packaging structure.

Background

A Micro Electro Mechanical System (MEMS), which is a new scientific technology developed on the basis of microelectronic technology and integrating micromachine, microsensors, microactuator, signal processing, and intelligent control. The MEMS inertial sensor comprises an acceleration sensor, an angular velocity sensor, an IMU inertial measurement unit, an attitude heading reference system and the like.

The MEMS inertial sensor contains a movable mass block inside, the movable mass block realizes the detection function of acceleration and rotating speed, but because the movable mass block can move, the movable mass block often causes various early damages to a mass block body due to external stress. Early damage of the MEMS inertial sensor is divided into damage in a packaging process, damage in a testing process and damage in a surface mounting process. At present, the MEMS inertial sensor is mostly packaged by adopting epoxy resin, the Young modulus of the epoxy resin at room temperature is 800-.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention is directed to a package structure of an inertial sensor, which realizes protection of a mass block inside a sensor die.

According to an aspect of the utility model, a provide an inertial sensor's packaging structure, include: a substrate having opposing first and second surfaces;

a first die attached to a first surface of the substrate;

a second die secured to the first die;

a frame structure secured to the first surface of the substrate with the first die and the second die positioned in the frame structure; and a molding compound on the first surface of the substrate and covering the first die and the second die and the frame structure.

Preferably, the frame structure is provided with a hollow hole.

Preferably, the Young's modulus of the frame structure is 190-210GPa, and the thermal expansion coefficient is 17 x 10^-6-20×10^-61/K。

Preferably, the package structure of the inertial sensor further includes: a first bond wire for connecting the second die to the substrate; a second bond wire for connecting the first die to the second die.

Preferably, the first die is secured to the first surface of the substrate by a first adhesive layer; the second die is secured to the first die by a second adhesive layer.

Preferably, the first adhesive layer and/or the second adhesive layer are both silicone layers.

Preferably, the first adhesive layer has a rectangular shape, and the second adhesive layer has a rectangular shape.

Preferably, the silica gel layer is a single-component thermosetting silica gel layer.

Preferably, the first bonding layer and/or the second bonding layer are/is a silica gel layer with Young modulus of 2-4 Mpa at room temperature.

Preferably, the thickness of silica gel layer is 20 ~ 100 um.

Preferably, the number of the first die is one or more, and the number of the second die is one or more.

Preferably, the first die is an inertial sensor die and the second die is a signal processing circuit die.

Preferably, the frame structure is a stainless steel frame.

Preferably, the substrate is at least one layer of a PCB board.

The utility model provides an among inertial sensor's the packaging structure, the adoption is fixed frame construction on the first surface of base plate will first tube core with the second tube core is located among the frame construction. Due to the high modulus of the frame structure, the stress generated to the sensor tube core in the packaging process is absorbed, so that the stress and the deformation caused by the external stress of the sensor tube core are avoided or reduced, the original physical characteristics of the movable block in the sensor are kept, and the excellent zero drift performance and temperature drift performance of the sensor are realized.

Further, the substrate and the first die and the second die are bonded together by using the silica gel layer. Due to the room-temperature low-modulus characteristic of the silica gel layer, stress generated to the sensor tube core in the packaging process is further reduced, and therefore protection of the mass block inside the sensor tube core is achieved.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

fig. 1 and 2 show a cross-sectional view and a top view, respectively, of a packaging structure of an inertial sensor provided according to an embodiment of the present invention.

Detailed Description

Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.

The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples.

The packaging structure of the present invention can be applied to a micro mechanical sensor structure, such as a MEMS sensor, or other structures.

Fig. 1 and 2 show a cross-sectional view and a top view, respectively, of a packaging structure of an inertial sensor provided according to an embodiment of the present invention. As shown in fig. 1 and 2, the package structure 100 of the inertial sensor includes a substrate 110, a first die 130 located on the substrate 110, a second die 150 located on the first die 130, and a frame structure 160 and a molding compound 170 located on the first substrate 110.

Wherein the substrate 110 has a first surface and a second surface opposite to each other. A first die 130 is secured to the first surface of the first substrate by a first adhesive layer 120; a second die 150 is secured to the first die 130 by a second adhesive layer 140; a frame structure 160 is secured to the first surface of the substrate 110 such that the first die 130 and the second die 150 are located in the frame structure 160.

In this embodiment, the substrate 110 is used to carry the first die 130 and the second die 150 thereon, and may be a PCB including at least two layers, but may also be a single-layer PCB in some embodiments.

The first die 130 and the second die 150 may be chips or devices, and the number thereof may be single or multiple. For example, the first die 130 is an inertial sensor die that contains fixed and movable elements inside. The second die 150 is a signal processing circuit die.

The first adhesive layer 120 and the second adhesive layer 140 are silicone layers. The Young modulus of the silica gel layer at room temperature is 2-4 Mpa. The thickness of silica gel layer includes but not limited to 20 ~ 100um, can change according to the silica gel volume of atress performance adjustment packing the thickness of silica gel layer. The material of the silica gel layer is single-component thermosetting silica gel, and the Young modulus of the silica gel layer at room temperature is one thousandth of that of the epoxy resin.

A first adhesive layer 120 is located between the substrate 110 and the first die 130, in contact with the first surface of the substrate 110 and the lower surface of the first die 130; a second adhesive layer 140 is located between the first die 130 and the second die 150 in contact with the upper surface of the first die 130 and the lower surface of the second die. The first adhesive layer 120 and the second adhesive layer 140 are rectangular in shape. The first adhesive layer 120 and the second adhesive layer 140 are formed by dispensing with TSE 322S.

A frame structure 160 is fixed on the first surface of the substrate 110 by dispensing, such that the first die 130 and the second die 150 are located in the frame structure 160. The frame structure 160 is a stainless steel frame, and each surface thereof is provided with a hollow hole 161 to reduce the weight of the plastic package body. The frame structure has Young's modulus of 200GPa and thermal expansion coefficient of 17 × 10^-6-20×10^-61/K. Due to the high modulus of the frame structure, stresses on the sensor die during packaging can be absorbed.

The molding compound 170 may be a resin-containing composite, ceramic, or the like, such as an epoxy, which is fixed to the substrate 110 to cover the first die 130 and the second die 150, so as to provide protection for the first die 130 and the second die 150 together with the substrate 110.

In a preferred embodiment, the package structure 100 further comprises a first bond wire 180 and a second bond wire 190, wherein the first bond wire 180 is used to connect the second die 150 to the substrate 110; the second bond wire 190 is used to connect the first die 130 to the second die 150.

In the present embodiment, the first bonding wire 180 and the second bonding wire 190 are metal wires, and the conductive material thereof is copper, tungsten, aluminum, silver, gold, or the like, or a combination thereof.

In the process of the loading procedure, a pick-up head of the loading machine picks up a first tube core from a cut blue film disc and places the first tube core on a substrate, and impact force is generated between the pick-up head and the substrate in the process of placing the tube core; in the gold wire bonding process, the cleaver can perform ultrasonic impact on a welding point; in the testing process, the testing clamp presses the packaging structure, and the stress of external pressing is transmitted to the sensor chip; in the mounting process, the temperature of the reflow oven is increased from the ambient temperature to 260 ℃, and is maintained at 260 ℃ for at least 20s, and strong thermal stress is generated in the packaging body due to the high temperature. In the above steps, the sensor tube core is damaged by impact force, pressure holding stress, and thermal stress. The package structure provided by the embodiment adopts the silica gel layer to fix between the substrate and the first die and between the first die and the second die, and is protected by the silica gel with low Young modulus, so that the package structure is prevented from being impacted by large stress.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An inertial sensor package, comprising:

a substrate having opposing first and second surfaces;

a first die attached to a first surface of the substrate;

a second die secured to the first die;

a frame structure secured to the first surface of the substrate with the first die and the second die positioned in the frame structure; and

a molding compound on the first surface of the substrate and covering the first and second dies and the frame structure.

2. The inertial sensor package according to claim 1, wherein the frame structure is provided with a hollowed-out hole.

3. The inertial sensor package structure according to claim 1, wherein the frame structure has a young's modulus of 190-^-6-20×10^-61/K。

4. The inertial sensor package of claim 1, further comprising:

a first bond wire for connecting the second die to the substrate;

a second bond wire for connecting the first die to the second die.

5. The inertial sensor package structure according to claim 1, wherein the first die is fixed on the first surface of the substrate by a first adhesive layer; the second die is secured to the first die by a second adhesive layer.

6. The encapsulation structure of the inertial sensor according to claim 5, wherein the first adhesive layer and/or the second adhesive layer are both silicone layers.

7. The packaging structure of an inertial sensor according to claim 5,

the first adhesive layer is rectangular in shape,

the second adhesive layer is rectangular in shape.

8. The encapsulation structure of the inertial sensor according to claim 6, wherein the silicone layer is a one-component thermosetting silicone layer.

9. The encapsulation structure of the inertial sensor according to claim 6, wherein the first adhesive layer and/or the second adhesive layer is a silicone layer having a Young's modulus at room temperature of 2-4 MPa.

10. The encapsulation structure of the inertial sensor of claim 6, wherein the thickness of the silicone layer is 20-100 um.

11. The package structure of an inertial sensor according to claim 1, wherein the first die is one or more in number and the second die is one or more in number.

12. The package structure of an inertial sensor according to claim 1, wherein the first die is an inertial sensor die and the second die is a signal processing circuit die.

13. The inertial sensor package of claim 1, wherein the frame structure is a stainless steel frame.

14. The inertial sensor package according to claim 1, wherein the substrate is at least one layer of a PCB board.