WO2020238773A1

WO2020238773A1 - Package structure and mobile terminal

Info

Publication number: WO2020238773A1
Application number: PCT/CN2020/091685
Authority: WO
Inventors: 曲林; 叶润清; 吕秀启; 史洪宾; 龙浩晖
Original assignee: 华为技术有限公司
Priority date: 2019-05-27
Filing date: 2020-05-22
Publication date: 2020-12-03
Also published as: CN110600432A

Abstract

The present application provides a package structure and a mobile terminal. The package structure comprises a substrate, wherein the substrate is provided with a first surface with a device. The package structure further comprises a sealing cavity cover used for protecting a pressure sensitive device. The sealing cavity cover is in sealed connection with the substrate. When the pressure sensitive device is arranged, the pressure sensitive device is located in a protective cavity of the sealing cavity cover and is electrically connected to the substrate. Furthermore, the package structure also comprises a first package layer, and the first package layer is used for packaging the device on the first surface of the substrate and packaging the sealing cavity cover. When the first package layer is formed, a package mold flow process is needed, and a mold flow pressure parameter of a package mold flow tends to be increased along with the increase of the size and the integration level of system integration. The pressure sensitive device is protected in the present application by means of the arranged sealing cavity cover, and the mold flow pressure is borne by means of the sealing cavity cover, such that the safety of the pressure sensitive device is improved, and the quality of the package structure is improved.

Description

Packaging structure and mobile terminal

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China, the application number is 201910443664.8, and the invention title is "a packaging structure and terminal equipment" on May 27, 2019, and it is filed on August 15, 2019 The State Intellectual Property Office of China, the application number is 201910754539.9, the title of the invention is "a packaging structure and mobile terminal" Chinese patent application priority, the entire content of which is incorporated into this application by reference.

Technical field

This application relates to the field of packaging technology, and in particular to a packaging structure and a mobile terminal.

Background technique

There are more and more scenarios where system-in-package chips are used in terminal products such as mobile phones, watches and system board module products. For example, RF-packaged chips have used system-in-package, and wearable smart watches have also applied system-in-package design. In the manufacturing process of the system-in-package chip, packaging processing is required, and the packaging mold flow process is required here. As the size and integration of system integration increase, the requirements for mold flow fillability will only become higher, which makes mold flow pressure parameters increase, and the increase in packaging integration requires use in the package The devices should be assembled using bare chips as much as possible. When the bare chip is used in the case of the original package size is small, the mold flow pressure is relatively low, and the pressure damage to the mold flow device is small. The increase in the solder joint density of the components in the package leads to a decrease in the height gap of the solder joints and an increase in the number of chips, which will require an increase in the mold flow pressure to achieve more reliable filling. The die and mold flow pressure sensitive devices (filters, filters, The reliability of crystal oscillator, etc.) has brought new challenges. In the existing packaging process, the injection pressure of the mold is generally 5-10 MPa, and some devices have already experienced a problem of failure due to excessive molding pressure at 6 MPa.

Summary of the invention

The present application provides a packaging structure and a mobile terminal, which are used to improve the safety of the pressure sensitive device of the mobile terminal, thereby improving the quality of the packaging structure.

In a first aspect, a package structure is provided, which is applied to a mobile terminal, wherein the package structure includes a substrate, which is basically used to carry a device, and the substrate has a first surface. When the device is set, the device can be set On the first surface. In addition, the packaging structure further includes a sealed cavity cover, which serves as a protection device for protecting the devices that cannot withstand greater pressure among the devices provided on the first surface. The sealed cavity cover is arranged on the first surface of the substrate and is connected to the substrate in a sealed manner. In addition, the sealed cavity cover has a protection cavity, and the device to be protected can be located in the protection cavity. The device to be protected is a pressure sensitive device, and the pressure sensitive device is the above-mentioned device that cannot withstand greater pressure. When the pressure sensitive device is set, the pressure sensitive device is located in the protection cavity and electrically connected to the substrate. In addition, the packaging structure further includes a first packaging layer for packaging the devices on the first surface of the substrate and packaging the sealed cavity cover. When forming the first encapsulation layer, a packaging mold flow process is required. As the size and integration of the system increase, the mold flow pressure parameter tends to increase. In this application, it is set The sealed cavity cover protects the pressure sensitive device, and the sealed cavity cover bears the pressure of the mold flow, thereby improving the safety of the pressure sensitive device and further improving the quality of the packaging structure.

In a specific implementation, the sealed cavity cover is connected to the substrate in a sealed manner. Through the sealed connection of the sealed cavity cover and the substrate, the protection cavity is isolated from the outside.

In a specific implementation, the sealed cavity cover is connected to the substrate by welding or adhesive connection. The sealing connection effect is achieved through different processes.

In a specific implementation, there is a gap between the sealed cavity cover and the pressure sensitive device. Improve the safety of pressure sensitive devices.

In a specific implementation, the sealed cavity cover includes an annular protective wall, and a protective cover covering the protective wall, and the protective cover and the protective wall are in a sealed connection. The sealed cavity cover is realized through different structures.

In a specific implementation, the protective wall and the protective cover are an integral structure. The sealed cavity cover is realized through different structures.

In a specific implementation, the sealed cavity cover is a sealed cavity cover made of metal or ceramic materials. The sealed cavity cover is prepared from different materials.

In a specific implementation, the sealed cavity cover includes a second packaging layer, and the second packaging layer wraps the pressure sensitive device. The pressure sensitive device is protected by the second encapsulation layer.

In a specific implementation, the thickness from the second packaging layer to the pressure sensitive device is greater than the set thickness to ensure that the second packaging layer can withstand the mold flow pressure.

In a specific implementation, the sealed cavity cover includes: a limit cover surrounding the pressure sensitive device, and a third encapsulation layer filled in the limit cover and wrapping the pressure sensitive device. The limit cover ensures the molding of the third packaging layer, and the pressure sensitive device is protected by the third packaging layer.

In a specific implementation, an opening is provided on the side of the limit cover facing away from the first surface. The third encapsulation layer is filled through the opening.

In a specific implementation, it further includes a limiting plate covering the opening, and the limiting plate and the limiting cover are hermetically connected. Seal again through the limit plate to protect the pressure sensitive device.

In a second aspect, a mobile terminal is provided. The mobile terminal includes a housing, and the packaging structure of any one of the foregoing disposed in the housing.

Description of the drawings

FIG. 1 is a schematic structural diagram of a mobile terminal provided by an embodiment of the application;

2 is a schematic diagram of the first package structure provided by an embodiment of the application;

FIG. 3a is a schematic diagram of a connection mode of the sealed cavity cover and the substrate provided by an embodiment of the application;

3b is a schematic diagram of another connection method between the sealed cavity cover and the substrate provided by an embodiment of the application;

Figure 4a is a schematic structural diagram of a sealed cavity cover provided by an embodiment of the application;

FIG. 4b is a schematic diagram of another structure of the sealed cavity cover provided by the embodiment of the application;

Fig. 5a is a schematic diagram of a package structure in the prior art;

Figure 5b is a schematic diagram of stress analysis of a bare chip in the prior art;

Figure 5c is a force analysis diagram of a pressure sensitive device provided by an embodiment of the application;

FIG. 6 is a schematic diagram of a second package structure provided by an embodiment of the application;

Figure 7 is a schematic diagram of the pressure of different pre-package materials and different pre-package sizes on pressure sensitive devices;

FIG. 8 is a schematic diagram of a third package structure provided by an embodiment of the application;

FIG. 9 is a schematic diagram of a fourth package structure provided by an embodiment of the application.

Detailed ways

In order to facilitate the understanding of the packaging structure provided by the embodiments of the present application, firstly, the application scenarios are explained. The packaging structure is applied to terminal products, such as mobile phones, tablet computers, or wearable devices (such as electronic watches, etc.).

As shown in FIG. 1, taking a mobile phone as an example, the mobile terminal includes a housing 20 and a printed circuit board arranged in the housing 20. The printed circuit board may be the main board 30 of the mobile terminal, and the printed circuit board is provided with a packaging structure. 10. When the package structure 10 is connected to the main board 30, the package structure 10 may be electrically connected to the main board 30 through LGA (Grid Array) or BGA (Ball Array). As shown in FIG. 1, the package structure 10 may be connected through BGA (FIG. 1 The solder ball array shown by a plurality of black dots) is electrically connected to the main board 30.

Referring to FIG. 2 together, FIG. 2 shows a schematic structural diagram of a package structure provided by an embodiment of the present application. The package structure 10 may include a substrate 11, and the substrate 11 may be a printed circuit board or other types of circuit boards. The substrate 11 has a first surface and a second surface opposite to each other, wherein the first surface is used to carry the device, and the second surface is used to connect to the main board 30 shown in FIG. 1.

Continuing to refer to FIG. 2, the first surface of the substrate 11 provided by the embodiment of the present application is provided with a plurality of devices, and the foregoing devices may be packaged chips, bare chips, passive devices, and other devices. When the device is connected to the substrate 11, a circuit layer is provided on the substrate 11, and the device can be electrically connected to the circuit layer of the substrate 11 through pads.

In order to protect the aforementioned devices, the packaging structure 10 provided by the embodiments of the present application may further include a first packaging layer 13 covering the first surface of the substrate 11 and used for packaging the aforementioned devices. In the specific packaging, the above-mentioned devices can be packaged by the packaging mold flow process. When the above-mentioned packaging mold flow process is sampled, the substrate 11 carrying the device needs to be placed in the mold, and then the high-pressure and high-temperature packaging is performed by the packaging equipment The material is filled into the mold and cooled and solidified. In the above process, the device needs to withstand greater mold flow pressure. Therefore, for the convenience of description, the above devices are divided here. The device that can withstand greater pressure during packaging is called compression-resistant device 12. The device that is subjected to greater pressure is called the pressure sensitive device 15, and the pressure sensitive device 15 may be a device such as a filter, a crystal oscillator, and the like. In order to ensure the safety of the pressure sensitive device 15 during packaging, the packaging structure 10 provided by the embodiment of the present application is further provided with a sealed cavity cover 14, which serves as a protection device for protecting the aforementioned pressure sensitive device 15 .

As shown in Figure 2, when the sealed cavity cover 14 is connected to the substrate 11, the sealed cavity cover 14 is provided on the first surface of the substrate 11 and is connected to the substrate 11 in a sealed manner, and when the sealed cavity cover 14 is connected to the substrate 11 Cover the pressure sensitive device 15. The sealed cavity cover 14 has a protective cavity, and the aforementioned pressure sensitive device 15 is located in the protective cavity. Continuing to refer to FIG. 2, the pressure sensitive device 15 is sealed in a protective space through the sealed cavity cover 14 and the substrate 11. When the packaging mold flow process is used for packaging, the sealed cavity cover 14 provides force against mold flow pressure, The mold flow pressure will not directly act on the pressure sensitive device 15. Therefore, the safety of the pressure sensitive device 15 can be improved. And in specific implementation, the sealed cavity cover 14 can not only protect a pressure sensitive device 15 as shown in FIG. 2, but the specific number of pressure sensitive devices 15 to be protected can be determined according to needs. When the number of pressure sensitive devices 15 is multiple, either different sealed cavity covers 14 can be used to protect one pressure sensitive device 15 respectively, or one sealed cavity cover 14 can be used to protect multiple pressure sensitive devices 15 at the same time, that is, In other words, one pressure sensitive device 15 may be provided in the cavity formed by the sealing of the sealed cavity cover 14 and the substrate 11, of course, multiple pressure sensitive devices 15 may also be provided, which is not limited in this application.

As shown in FIG. 3a, FIG. 3a shows a specific connection method between the sealed cavity cover 14 and the substrate 11. In FIG. 3a, the sealed cavity cover 14 and the substrate 11 can be completely sealed and welded by solder 101. During specific welding, the position where the sealed cavity cover 14 and the substrate 11 are welded can be plated (a metal layer is plated on the sealed cavity cover 14), and the plating layer is selected from a material that can react with the solder 101, that is can. And during welding, all the contact positions of the sealed cavity cover 14 and the substrate 11 are welded and sealed, so that a sealed protective space is formed between the sealed cavity cover 14 and the substrate 11.

As shown in FIG. 3b, FIG. 3b shows another specific connection between the sealed cavity cover 14 and the substrate 11. In FIG. 3b, the sealed cavity cover 14 is adhesively connected to the substrate 11 through an adhesive 102. In the specific bonding, first buckle the sealed cavity cover 14 to the pressure sensitive device 15, and then apply a circle of adhesive 102 around the sealed cavity cover 14. The adhesive 102 connects the sealed cavity cover 14 with The substrate 11 is bonded and connected, and during coating, the adhesive 102 is continuously applied to ensure a sealed connection between the sealed cavity cover 14 and the substrate 11. In addition, the surface of the sealed cavity cover 14 for connecting with the substrate 11 can be coated with an adhesive 102. When the sealed cavity cover 14 is covered on the substrate 11, the adhesive 102 is used for pre-positioning. Afterwards, a circle of adhesive 102 is applied for bonding, so as to improve the bonding strength between the sealed cavity cover 14 and the substrate 11, and at the same time, the sealing effect between the sealed cavity cover 14 and the substrate 11 can be improved. .

When the sealed cavity cover 14 is specifically prepared, the material of the sealed cavity cover 14 can be metal, ceramic, or resin, which can provide certain structural strength protection. The purpose is to make the sealed cavity cover 14 have a higher structural strength to absorb the size of the subsequent mold flow pressure. If the strength of the material itself is high, the thickness of the sealed cavity cover 14 can be designed to be slightly thinner. And for the structure of the sealed cavity cover 14, either an integrated structure or a split structure may be adopted. As shown in FIG. 4a, the sealed cavity cover 14 shown in FIG. 4a adopts an integrated structure. At this time, the sealed cavity cover 14 includes a protective wall 142 and a protective cover 141, and the protective wall 142 and the protective cover 141 are integrally formed When preparing, it can be made of metal material by stamping or casting process. When using an integrated structure, the sealed cavity cover 14 has good pressure resistance, and when it is connected to the substrate 11, only sealing is required. It is sufficient to seal the gap between the cavity cover 14 and the substrate 11.

As shown in FIG. 4b, FIG. 4b shows another structure of the sealed cavity cover 14. In FIG. 4b, the sealed cavity cover 14 includes an annular protective wall 142, and a protective cover 141 covering the protective wall 142, and the protective cover 141 and the protective wall 142 are connected in a sealed manner. During specific preparation, the protective wall 142 and the protective cover 141 can be sealed and connected by welding or bonding. If the method of welding is adopted, the protective wall 142 and the protective cover 141 are made of metal materials, and then the protective cover 141 is covered on the protective wall 142, and the solder 143 is welded to make the protective cover 141 and the protective wall 142 sealed. connection.

Refer to FIG. 2 and FIG. 5a together, wherein FIG. 5a shows a schematic diagram of a package structure in the prior art. The packaging structure in the prior art includes a substrate 1, a device 2 and a device 4 carried on the substrate 1, and an encapsulation layer 3 encapsulated on the device 2 and the device 4. During packaging, the encapsulation layer 3 is directly connected to the device 2 and Device 4 contacts. In order to facilitate understanding of the difference between the packaging structure provided by the embodiment of the present application and the packaging structure in the prior art. Refer to FIG. 5b and FIG. 5c together. FIG. 5b shows the mold flow pressure of the device in the prior art, and FIG. 5c shows the mold flow pressure of the pressure sensitive device provided by the embodiment of the present application. First, referring to Fig. 5b, in the prior art packaging structure packaging, since the packaging material directly acts on the device 4, the device 4 is subjected to mold flow pressure in all directions up, down, left, right, front, and back. For devices with relatively small stress, damage is extremely easy. In the packaging structure provided by the embodiment of the present application, since the pressure sensitive device 15 is sealed in a protective space by the sealed cavity cover 14 and the substrate 11, the mold flow pressure is all applied to the sealed cavity cover 14 during packaging. , And the sealed cavity cover 14 has a certain strength, so it can provide a force against the pressure of the mold flow. In addition, when the sealed cavity cover 14 covers the pressure sensitive device 15, there is a certain gap between the sealed cavity cover 14 and the pressure sensitive device 15, so even if the sealed cavity cover 14 is deformed, it will not be squeezed. The pressure sensitive device 15 better guarantees the safety of the pressure sensitive device 15.

In addition, when using the technology of Figure 1, in order to solve the problem of squeezing the device, it is often used to optimize device selection, select device specifications with high pressure resistance, or use lower mold flow pressure to reduce damage to the device. The first method is to avoid stress damage to the device caused by excessive mold flow pressure. Reducing the mold flow pressure will bring about insufficient encapsulation, and cause problems such as encapsulation holes or interface cracks due to insufficient interface bonding. The use of devices with high withstand voltage will further increase the constraints on the devices, which may cause insufficient production capacity. However, in the package structure provided by the embodiment of the present application, due to the protection of the sealed cavity cover, there is no need to reduce the mold flow pressure, and the device does not need to be optimized, which can not only reduce the requirements for device selection, but also ensure the packaging reliability.

As shown in Figure 6, Figure 6 shows another package structure. The same reference numerals in FIG. 6 can refer to the reference numerals in FIG. 2. The difference between the packaging structure provided in FIG. 6 and the packaging structure provided in FIG. 2 lies in the difference of the sealed cavity cover. In Figure 6, the sealed cavity cover uses an encapsulation layer to provide sealing. At this time, the sealed cavity cover includes the second packaging layer 16. The second packaging layer 16 wraps the pressure sensitive device 15. In the specific setting, one second encapsulation layer 16 may only wrap one pressure sensitive device 15, and when there are multiple pressure sensitive devices 15, different second encapsulation layers 16 may be used to separately wrap each pressure sensitive device 15; Or when the multiple pressure sensitive devices 15 are relatively close, the multiple pressure sensitive devices 15 can also be sealed with a second encapsulation layer 16. When the second encapsulation layer 16 is specifically prepared, the pressure-sensitive device 15 is also sealed by the packaging mold flow process, but since the second encapsulation layer 16 only encapsulates the pressure-sensitive device 15, a smaller mold flow pressure can be used. It is: the mold flow pressure for preparing the second encapsulation layer 16 is lower than the mold flow pressure for preparing the first encapsulation layer 13. Therefore, the pressure sensitive device 15 can be encapsulated by the second encapsulation layer 16, and the first encapsulation layer 13 can be prepared after the second encapsulation layer 16 is cured, so as to ensure that the second encapsulation layer 13 is prepared when the first encapsulation layer 13 is prepared. The layer 16 can protect the pressure sensitive device 15.

6, when the second encapsulation layer 16 is prepared, the pressure sensitive device 15 is wrapped and sealed by the second encapsulation layer 16. Therefore, when the first encapsulation layer 13 is prepared, mold flow pressure will not be caused to the pressure sensitive device 15. Moreover, the effect of the second encapsulation layer 16 against mold flow pressure is related to the thickness of the second encapsulation layer 16. Therefore, the thickness of the second encapsulation layer 16 to the pressure sensitive device 15 can be greater than the set thickness during installation to ensure the second The encapsulation layer 16 can withstand the mold flow pressure, and the set thickness can be limited according to actual needs, which is not specifically limited here. Refer to FIG. 7 together, which shows a schematic diagram of the pressure of different pre-package materials and different pre-package sizes on the pressure-sensitive device 15, that is, the second package layer 16 with different thicknesses can provide resistance to mold flow. pressure. It can be seen from FIG. 7 that as the thickness of the second packaging layer 16 continues to increase, the mold flow pressure that the second packaging layer 16 can resist continues to increase.

As shown in FIG. 8, FIG. 8 shows another package structure provided by an embodiment of the present application, wherein the same reference numerals in FIG. 8 can refer to those shown in FIG. 2 and FIG. 6. The difference between the packaging structure shown in FIG. 8 and the packaging structure shown in FIG. 6 lies in the structure of the sealed cavity cover. In the packaging structure shown in FIG. 8, the sealed cavity cover includes: a limit cover surrounding the pressure sensitive device 15, the limit cover is a cylindrical structure, and the top and bottom ends of the limit cover are open; The bottom of the limit cover is connected with the first surface of the substrate 11 by welding or by bonding with adhesive. An opening is provided on the side of the limit cover facing away from the first surface, and the packaging material is filled into the limit cover through the opening by a packaging mold flow process, and the pressure sensitive device 15 is wrapped. After cooling and solidification, a third encapsulation layer 17 that wraps the pressure sensitive device 15 is formed. Then, the first encapsulation layer 13 is prepared through the encapsulation mold flow process to encapsulate all devices.

Referring to FIG. 9, FIG. 9 shows a schematic diagram of another package structure provided by an embodiment of the present application. The same reference numbers in FIG. 9 can be referred to as shown in FIG. 2 and FIG. 6 and FIG. 8. The difference between the packaging structure shown in FIG. 9 and the packaging structure shown in FIG. 8 lies in the structure of the sealed cavity cover. In the packaging structure shown in FIG. 9, the sealed cavity cover includes: a limit cover 192 surrounding the pressure sensitive device 15, the limit cover 192 is a cylindrical structure, and the top and bottom ends of the limit cover 192 are open; The bottom of the limit cover 192 is connected to the first surface of the substrate 11 by welding or by bonding with adhesive. An opening is provided on the side of the limit cover 192 facing away from the first surface, and the encapsulation material is filled into the limit cover 192 through the opening by a packaging mold flow process, and the pressure sensitive device 15 is wrapped to form the third encapsulation layer 17. The sealed cavity cover may further include a limiting plate 191 covering the opening, and the limiting plate 191 is in sealed connection with the limiting cover 192. During the specific connection, the limit plate 191 and the limit cover 192 are sealed and connected by welding. When the limit cover 192 and the substrate 11 are sealed and connected, the limit cover 192, the limit plate 191 and the substrate 11 enclose a sealed space to protect the pressure sensitive device 15. At this time, there are two layers of protection outside the pressure sensitive device 15: a cover composed of the third encapsulation layer 17, the limit cover 192 and the limit plate 191. The pressure sensitive device 15 is protected by the two-layer structure, and the safety of the pressure sensitive device 15 is better improved.

Continuing to refer to FIG. 1, an embodiment of the present application also provides a mobile terminal. The mobile terminal includes a housing 20 and a printed circuit board provided in the housing 20. The printed circuit board may be the main board 30 of the mobile terminal. A package structure 10 is provided on the printed circuit board. The packaging structure 10 can be any of the aforementioned packaging structures. When the package structure 10 is connected to the main board 30, the package structure 10 can be electrically connected to the main board 30 through LGA (Grid Array) or BGA (Ball Array). As shown in FIG. 1, the package structure 10 is connected through BGA (Ball Array). ) Is electrically connected to the motherboard 30. The pressure sensitive device is protected by the sealed cavity cover, and the pressure of the mold flow is absorbed by the sealed cavity cover, thereby improving the safety of the pressure sensitive device and further improving the quality of the packaging structure.

The above are only specific implementations of this application, but the scope of protection of this application is not limited to this. Anyone familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this application, and they should all cover Within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Claims

A packaging structure, characterized in that it comprises:

A substrate, the substrate having a first surface;

The sealed cavity cover is arranged on the first surface of the substrate and is connected to the substrate in a sealed manner; the sealed cavity cover has a protective cavity;

A pressure sensitive device located in the protective cavity and electrically connected to the substrate;

The first encapsulation layer encapsulates the sealed cavity cover.
The package structure according to claim 1, wherein the sealed cavity cover is in sealed connection with the substrate.
The package structure according to claim 2, wherein the sealed cavity cover is connected to the substrate by welding or bonding.
The package structure of claim 2, wherein a gap is provided between the sealed cavity cover and the pressure sensitive device.
The packaging structure according to claim 2, wherein the sealed cavity cover comprises an annular protective wall, and a protective cover covering the protective wall, and the protective cover and the protective wall are sealed connection.
The packaging structure of claim 5, wherein the protective wall and the protective cover are an integral structure.
3. The packaging structure of claim 1, wherein the sealed cavity cover is a second packaging layer, and the second packaging layer wraps the pressure sensitive device.
The packaging structure according to claim 1, wherein the sealed cavity cover comprises: a limit cover surrounding the pressure sensitive device, and a limit cover filled in the limit cover and wrapped around the pressure sensitive device The third packaging layer.
8. The packaging structure of claim 8, wherein the limit cover is provided with an opening on a side facing away from the first surface.
9. The packaging structure of claim 9, further comprising a limiting plate covering the opening, and the limiting plate and the limiting cover are hermetically connected.
A mobile terminal, characterized by comprising a casing, and the packaging structure according to any one of claims 1 to 10 arranged in the casing.