Sensor package structure against mechanical stress and method for manufacturing the same

Abstract

The application provides a mechanical stress-resistant sensor packaging structure and a preparation method thereof. The mechanical stress-resistant sensor packaging structure comprises a substrate and a functional chip assembly arranged on the substrate. An annular inner shell is arranged on the substrate, and the bottom of the functional chip assembly is fixed in the annular inner shell through adhesive. The adhesive is limited in the annular inner shell. The application can solve the problem of poor mechanical stress resistance of the existing sensor structure.

Description

Technical Field

[0001] This invention relates to the field of sensor design technology, and more specifically, to a sensor packaging structure resistant to mechanical stress and its fabrication method. Background Technology

[0002] In the era of the Internet of Things, sensors have become standard components in smart hardware such as mobile phones, watches, and computers. These smart devices achieve different detection functions by configuring different sensors; for example, temperature sensors are used to measure ambient temperature, and pressure sensors are used to measure pressure.

[0003] In practical use, smart devices such as mobile phones, watches, and computers permeate every aspect of users' lives. During use, they encounter various mechanical actions, such as a mobile phone suddenly falling from a height, a watch being accidentally placed in a washing machine, or a computer being placed on a vibrating motorcycle. These high-intensity mechanical actions place high demands on the reliability of the sensors inside these smart devices. If the sensor design is inadequate, it is highly likely that under high-intensity mechanical conditions, the internal sensor components will vibrate, or even cause the gold wire to break, resulting in performance failure.

[0004] Based on the aforementioned technical issues, there is an urgent need for a sensor structure that can effectively resist mechanical stress in order to meet the needs of smart hardware in different application scenarios. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a sensor packaging structure and its preparation method that are resistant to mechanical stress, so as to solve the problem of poor mechanical stress resistance of existing sensor structures.

[0006] The mechanical stress-resistant sensor packaging structure provided by the present invention includes a substrate and a functional chip assembly disposed on the substrate. An annular inner shell is provided on the substrate, and the bottom of the functional chip assembly is fixed inside the annular inner shell by adhesive; wherein the adhesive is confined within the annular inner shell.

[0007] Alternatively, the thickness of the adhesive can be less than the height of the annular inner shell.

[0008] In addition, an alternative solution is, An outer shell assembly is disposed on the substrate, covering the functional chip assembly and the annular inner shell; wherein, the outer shell assembly includes a wall shell surrounding the functional chip assembly.

[0009] Alternatively, the wall shell can be filled with potting compound that covers the solder joints of the functional chip assembly.

[0010] Alternatively, an optional solution is to provide a glue inlet at the top of the wall shell, and the outer shell assembly further includes a top shell adapted to the glue inlet; and, After the potting compound inside the wall shell has been filled through the potting port, the potting port is fixed and sealed by the top shell.

[0011] Alternatively, the functional chip assembly may include an ASIC chip fixed to the substrate by the adhesive and a MEMS chip fixed to the ASIC chip.

[0012] Alternatively, gold wires are connected between the ASIC chip and the MEMS chip, as well as between the ASIC chip and the substrate, and each gold wire is fixed by the potting compound.

[0013] Alternatively, the substrate can be a PCB board.

[0014] Alternatively, at least one through hole can be provided on the top shell.

[0015] On the other hand, the present invention also provides a method for fabricating a sensor packaging structure resistant to mechanical stress as described above, the method comprising: An annular inner shell is mounted on the substrate; The functional chip assembly is bonded and fixed inside the annular inner shell by an adhesive, wherein the adhesive is confined within the annular inner shell; A wall shell surrounding the functional chip assembly is mounted on the substrate; wherein, an injection port is provided at the top of the wall shell; Encapsulating adhesive is injected into the wall shell through the injection port to cover the solder joints of the functional chip assembly; A top shell covering the glue inlet is attached to the top of the wall shell.

[0016] Compared with existing roof expansion joint design technology, the sensor packaging structure and its preparation method for resisting mechanical stress provided by the present invention have the following beneficial effects: by setting an annular inner shell around the adhesive, it is possible to effectively prevent the adhesive from shaking with the substrate, avoid gold wire breakage and solder joint detachment, thereby significantly improving the overall sensor's resistance to mechanical stress; in addition, by setting the outer shell assembly as a wall shell with a filling port and a top shell for sealing the filling port, it is possible to orderly realize the filling of the wall shell and the sealing of the filling port during the actual preparation process, thereby preparing a sensor packaging structure with the internal covering of the filling adhesive of the solder joints of the functional chip components.

[0017] To achieve the foregoing and related objectives, one or more aspects of the invention include the features which will be described in detail below and specifically pointed out in the claims. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to include all such aspects and their equivalents. Attached Figure Description

[0018] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings and the contents of the claims, and with a more complete understanding of the invention. In the drawings: Figure 1 This is a schematic diagram of an existing sensor packaging structure; Figure 2 This is a front cross-sectional view of a sensor packaging structure resistant to mechanical stress provided according to an embodiment of the present invention; Figure 3 This is a partially enlarged view of a sensor packaging structure resistant to mechanical stress according to an embodiment of the present invention; Reference numerals: substrate 1', soft adhesive 2', functional chip 3', outer shell 4', substrate 1, adhesive 2, ASIC chip 3, MEMS chip 4, annular inner shell 5, potting compound 6, wall shell 7, gold wire 8, top shell 9. Detailed Implementation

[0019] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for ease of description of one or more embodiments.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate structural component; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Before detailing the mechanical stress-resistant sensor packaging structure provided by this invention, a brief overview of existing sensor packaging structures will be provided. Figure 1 Existing sensor packaging structures are shown, such as Figure 1 As shown, the existing sensor packaging structure includes a substrate 1' and a housing 4' fixed on the substrate 1'. A functional chip 3' is disposed inside the housing 4'. The functional chip 3' is bonded to the surface of the substrate 1' by a soft adhesive 2'. In actual use, when the entire sensor is subjected to a large mechanical action (such as an impact), the soft adhesive 2' at the bottom of the functional chip 3' will shake, causing slight displacement of the functional chip soft adhesive. This, in turn, causes the gold wire (not marked in the figure) on the functional chip soft adhesive to shift. In severe cases, it can even cause the gold wire to break, causing the entire sensor to lose its detection function.

[0022] The structure of the mechanical stress-resistant sensor packaging structure provided by this invention is described in detail below. Figure 2 The front cross-sectional view of the sensor packaging structure resistant to mechanical stress provided according to an embodiment of the present invention is shown. Figure 3 A partially enlarged structure of a sensor packaging structure resistant to mechanical stress provided according to an embodiment of the present invention is shown.

[0023] Combination Figure 2 and Figure 3As can be seen, the sensor packaging structure for resisting mechanical stress provided in the embodiments of the present invention includes a substrate 1 (such as a PCB board, i.e., a printed circuit board) for carrying the internal functional chip components of the sensor as a carrier and the functional chip components disposed on the substrate 1. The functional chip components are connected to the circuits on the substrate 1 through gold wires 8, pins, etc., so as to realize electrical connection with other external devices or electronic devices through the circuits on the substrate 1 to complete the transmission of detection signals.

[0024] In the sensor packaging structure for resisting mechanical stress provided by the present invention, in order to improve the sensor's resistance to mechanical stress, an annular inner shell 5 is first set (attached) around the mounting preset area of ​​the functional chip assembly on the substrate 1, and then the bottom of the functional chip assembly is fixed on the substrate 1 inside the annular inner shell 5 by adhesive 2; at this time, the adhesive 2 is correspondingly limited inside the annular inner shell 5.

[0025] In actual use, when the sensor is subjected to large mechanical movements, although the adhesive 2 may tend to shake, the fixed position of the annular inner shell restricts the adhesive 2. At this time, the inner walls around the annular inner shell will generate a corresponding reaction force on the adhesive 2, making the actual shaking of the adhesive 2 very small (even negligible). Correspondingly, the displacement of the functional chip component is also very small (even negligible). Therefore, the gold wire 8 on the functional chip component is basically unaffected, thus significantly improving the sensor's resistance to mechanical stress.

[0026] It should be noted that in the actual design process, the height of the inner ring shell needs to be slightly higher than the thickness of adhesive 2, and not too low. If the height of the inner ring shell is lower than the thickness of adhesive 2, adhesive 2 will overflow from the top of the inner ring shell to the outside, thus losing the function of the inner ring shell in limiting adhesive 2. Of course, the height of the inner ring shell cannot be too high either. If the inner ring shell is designed to be too high, when mounting functional chip components, if adhesive is applied using a perimeter scribing method, the scribing nozzle may come into contact with the inner ring shell. Therefore, the height of the inner ring shell should be designed to ensure that the scribing nozzle does not touch the inner ring shell.

[0027] In another specific embodiment of the present invention, in order to further improve the sensor's resistance to mechanical stress, the present invention also proposes a scheme of mounting a wall shell 7 + filling with protective adhesive + mounting a top shell 9.

[0028] Specifically, in order to protect the functional chip components on the substrate 1, an outer shell assembly covering the functional chip components and the annular inner shell 5 is also provided on the substrate 1, and potting compound 6 covering the solder joints of the functional chip components is filled inside the outer shell assembly.

[0029] Furthermore, to facilitate the potting of the housing assembly with potting compound 6, the housing assembly may include a wall shell 7 surrounding the functional chip assembly, the wall shell 7 being filled with potting compound 6 covering the solder joints of the functional chip assembly, and a potting port being provided at the top of the wall shell 7. The housing assembly also includes a top shell 9 adapted to the potting port.

[0030] In the actual manufacturing process, after the functional chip assembly is mounted, a wall shell 7 is mounted on the substrate 1, surrounding the functional chip assembly. The top of the wall shell 7 has a potting port for potting the interior. The wall shell 7 acts like a sealed wall, providing a container for the potting adhesive 6. After mounting the wall shell 7, the interior is potted. The amount of adhesive is sufficient to submerge the solder joints on the functional chip assembly, further reducing the risk of gold wire 8 breaking due to movement of the adhesive 2. After potting, a top shell 9 is mounted at the potting port on the top of the wall shell 7 to securely seal the potting port. The top shell 9 protects the internal chips and devices of the sensor.

[0031] Furthermore, for certain types of sensors that require openings to sense external physical signals, such as microphones and barometric pressure sensors, functional openings, such as acoustic or vent holes, can be made on the top shell 9 to allow communication between the sensor's internal and external environments. Conversely, for other sensors that do not require communication with the external environment, openings on the top shell 9 are unnecessary, such as accelerometers.

[0032] On the other hand, to further illustrate the fabrication process of the mechanical stress-resistant sensor packaging structure provided by the present invention, the present invention also provides a method for fabricating the aforementioned mechanical stress-resistant sensor packaging structure, the method comprising: An annular inner shell 5 is attached to substrate 1; The functional chip assembly is bonded and fixed inside the annular inner shell 5 by adhesive, wherein it is limited within the annular inner shell 5. A wall shell 7 surrounding the functional chip assembly is mounted on the substrate 1; wherein, an injection port is provided at the top of the wall shell 7. Encapsulating adhesive 6, covering the solder joints of the functional chip assembly, is injected into the wall shell 7 through the injection port. A top shell 9 is attached to the top of the wall shell 7 to cover the glue inlet.

[0033] It should be noted that, for a sensor, the internal functional chip components typically include an ASIC (Application-Specific Integrated Circuit) chip 3 fixed to the substrate 1 by the adhesive 2, and a MEMS (Micro-Electro-Mechanical Systems) chip 4 fixed to the ASIC chip. The ASIC chip is a dedicated integrated circuit chip, a signal processing chip specifically designed for a particular type of sensor, not a general-purpose chip. Its core function is to transform the sensor's raw, weak signal into a usable, stable, and standard electrical signal. The MEMS chip is the sensor's sensing component, responsible for converting physical signals into electrical signals; it is the micro-mechanical structure chip that truly senses external signals.

[0034] Furthermore, to enable electrical signal transmission between the MEMS chip and the ASIC chip, gold wires 8 are connected between the ASIC chip and the MEMS chip, as well as between the ASIC chip and the substrate 1. During actual operation, the MEMS chip converts sensed external signals into electrical signals and transmits them to the ASIC chip via the gold wires 8. The ASIC chip optimizes the electrical signals received from the MEMS chip (e.g., amplification, compensation, calibration, conversion, etc.). The optimized electrical signals from the ASIC chip are then transmitted back to the substrate 1 via the gold wires 8, and finally transmitted to external devices or components through the circuitry on the substrate 1. It should be noted that to improve the mechanical stress resistance of each gold wire 8, each gold wire 8 can be fixed by embedding it with the potting compound 6.

[0035] The following section uses a functional chip component including a MEMS chip and an ASIC chip as an example to further illustrate the fabrication method of the sensor packaging structure resistant to mechanical stress provided by the present invention.

[0036] First, an inner ring shell is attached to the periphery of the preset position of the ASIC chip on substrate 1. Then, the ASIC chip is attached to the preset position on substrate 1 using adhesive. Subsequently, the MEMS chip is attached to the ASIC chip. Finally, gold wires 8 are used to complete the electrical connection between the ASIC chip and the MEMS chip, as well as the electrical connection between the ASIC chip and substrate 1. In actual use, when the sensor is subjected to significant mechanical movement, although the adhesive 2 may tend to wobble, the actual wobble is very small due to the constraint of the inner ring shell. The displacement of the ASIC chip is also very small (and correspondingly, the displacement of the MEMS chip is also very small). Therefore, the gold wires 8 connecting the ASIC chip and the MEMS chip are essentially unaffected. It should be noted that the height of the inner ring shell needs to be slightly higher than the thickness of the adhesive 2 and cannot be too short. When the height of the inner ring shell is shorter than the adhesive 2, the adhesive 2 will overflow outside the inner ring shell, thus losing the function of the inner ring shell in constraining the adhesive 2. Of course, the height of the inner shell of the ring cannot be too high. If the height of the inner shell of the ring is too high, when mounting the ASIC chip, if the glue is applied by swiping around the perimeter, the glue applicator may come into contact with the inner shell of the ring.

[0037] Then, after completing the mounting of the ASIC chip and MEMS chip and the connection of the gold wire 8, the wall shell 7 is mounted on the substrate 1. The top of the wall shell 7 is provided with a potting port for easy potting. The wall shell 7 acts as a sealed enclosure to provide a container for the potting compound 6. After mounting the wall shell 7, potting is performed. The amount of potting adhesive needs to completely submerge all solder points on the ASIC chip, thereby further reducing the risk of gold wire 8 breaking when the adhesive 2 on the bottom of the ASIC chip shakes. At the same time, the amount of potting adhesive should not submerge the upper surface of the MEMS chip, as there is a sensitive film on the upper surface of the MEMS chip, and submerging the MEMS chip may cause the potting adhesive 6 to have a certain impact on the response performance of the MEMS chip. After potting, the top shell 9 is mounted. The function of the top shell 9 is to protect the inside of the sensor, especially the MEMS chip, ASIC chip, and gold wire 8.

[0038] As per the above reference Figure 2 and Figure 3 The mechanical stress-resistant sensor packaging structure and its fabrication method according to the present invention are described by way of example. However, those skilled in the art should understand that various modifications can be made to the mechanical stress-resistant sensor packaging structure and its fabrication method proposed in the present invention without departing from the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the content of the appended claims.

Claims

1. A sensor packaging structure resistant to mechanical stress, comprising a substrate and a functional chip assembly disposed on the substrate; characterized in that, An annular inner shell is provided on the substrate, and the bottom of the functional chip assembly is fixed inside the annular inner shell by adhesive; wherein the adhesive is confined within the annular inner shell.

2. The sensor packaging structure resistant to mechanical stress as described in claim 1, characterized in that, The thickness of the adhesive is less than the height of the annular inner shell.

3. The sensor packaging structure resistant to mechanical stress as described in claim 2, characterized in that, A housing assembly covering the functional chip assembly and the annular inner shell is disposed on the substrate; wherein, The housing assembly includes a wall shell surrounding the functional chip assembly.

4. The sensor packaging structure resistant to mechanical stress as described in claim 3, characterized in that, The wall shell is filled with potting compound that covers the solder joints of the functional chip assembly.

5. The sensor packaging structure resistant to mechanical stress as described in claim 4, characterized in that, A glue-filling port is provided at the top of the wall shell, and the outer shell assembly further includes a top shell adapted to the glue-filling port; and, After the potting compound inside the wall shell has been filled through the potting port, the potting port is fixed and sealed by the top shell.

6. The sensor packaging structure resistant to mechanical stress as described in claim 5, characterized in that, The functional chip assembly includes an ASIC chip fixed to the substrate by the adhesive and a MEMS chip fixed to the ASIC chip.

7. The sensor packaging structure resistant to mechanical stress as described in claim 6, characterized in that, Gold wires are connected between the ASIC chip and the MEMS chip, as well as between the ASIC chip and the substrate, and each gold wire is fixed by the potting compound.

8. The sensor packaging structure resistant to mechanical stress as described in claim 7, characterized in that, The substrate includes a PCB board.

9. The sensor packaging structure resistant to mechanical stress as described in claim 8, characterized in that, At least one through hole is provided on the top shell.

10. A method of manufacturing a mechanically-stressed sensor package structure according to any one of claims 1 to 9, characterized by, include: An annular inner shell is mounted on the substrate; The functional chip assembly is bonded and fixed inside the annular inner shell by an adhesive, wherein the adhesive is confined within the annular inner shell; A wall shell surrounding the functional chip assembly is mounted on the substrate; wherein, an injection port is provided at the top of the wall shell; Encapsulating adhesive is injected into the wall shell through the injection port to cover the solder joints of the functional chip assembly; A top shell covering the glue inlet is attached to the top of the wall shell.

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