Circuit board assembly, method of manufacturing the same, and electronic device

Abstract

Embodiments of the present application disclose a circuit board assembly, a manufacturing method thereof and an electronic device. The circuit board assembly comprises a circuit board, a chip arranged on the circuit board, a metal layer covering at least a surface of the chip away from the circuit board, a shielding structure arranged on the circuit board and surrounding the chip, the shielding structure being provided with a hollow part, the shielding structure being overlapped with the metal layer at the hollow part, a heat-conducting layer arranged on a surface of the metal layer away from the chip, at least part of the heat-conducting layer being arranged in the hollow part, and a heat sink arranged on the heat-conducting layer. The embodiments of the present application can improve the heat dissipation efficiency and reduce the distance between the heat sink and the chip.

Description

Technical Field

[0001] This application relates to the field of circuit board technology, and in particular to a circuit board assembly and its manufacturing method, and electronic equipment. Background Technology

[0002] Chips generate electromagnetic radiation noise when they are working. If this electromagnetic radiation noise is received by the antenna in the electronic device, it will cause the antenna sensitivity to deteriorate, which in turn leads to a decrease in communication quality. Therefore, it is necessary to shield the chip.

[0003] In related technologies, a circuit board contains a chip and a shielding structure. The shielding structure covers the chip to form a shielding cavity with the circuit board, thus shielding the chip. The chip generates heat during operation; therefore, the electronic device also includes a heat sink. The heat sink is located on the side of the shielding structure away from the chip, and a thermally conductive layer is provided between the heat sink and the shielding structure, as well as between the shielding structure and the chip. This results in a large number of structural layers between the heat sink and the chip, and a relatively large distance between them, leading to low heat dissipation efficiency. Summary of the Invention

[0004] This application provides a circuit board assembly and its manufacturing method, as well as an electronic device, which can improve heat dissipation efficiency.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect of this application, a circuit board assembly is provided. The circuit board assembly includes a circuit board, a chip, a metal layer, a shielding structure, a thermally conductive layer, and a heat sink.

[0007] The chip is mounted on a circuit board. A metal layer covers at least the surface of the chip facing away from the circuit board. A shielding structure is mounted on the circuit board and surrounds the chip. The shielding structure has cutouts, and the shielding structure overlaps with the metal layer at the cutouts. Thus, the circuit board, shielding structure, and metal layer together form a shielding cavity, within which the chip is located, thereby shielding the chip.

[0008] A thermally conductive layer is located on the surface of the metal layer facing away from the chip, and at least a portion of the thermally conductive layer is located within a cutout. A heat sink is disposed on the thermally conductive layer. That is, the thermally conductive layer is located between the metal layer and the heat sink. A thermally conductive layer is disposed between the metal layer and the heat sink, forming a thermally conductive interface between the metal layer and the thermally conductive layer, and another thermally conductive interface is formed between the thermally conductive layer and the heat sink; in other words, two thermally conductive interfaces are formed between the metal layer and the heat sink. Since the metal layer covers the surface of the chip, during chip heat dissipation, the metal layer and the chip can be considered as a single unit for heat dissipation. Therefore, it can also be said that two thermally conductive interfaces are formed between the chip and the heat sink. This reduces the number of thermally conductive interfaces between the chip and the heat sink, thereby reducing the obstruction of heat dissipation by these interfaces and improving heat dissipation efficiency.

[0009] In addition, a metal layer and a thermally conductive layer are provided between the chip and the heat sink. Compared with the three-layer structure in related technologies, this application can reduce the number of structural layers between the chip and the heat sink, thereby reducing the distance between the chip and the heat sink and thus reducing the thickness of the entire circuit board assembly.

[0010] In some embodiments of this application, the metal layer also covers the sides of the chip. Specifically, the chip may include four sides, and the metal layer may cover some of these four sides. For example, the metal layer may cover one, two, or three sides. Alternatively, the metal layer may cover all four sides, i.e., the metal layer covers all four sides. In this way, the metal layer covers the surface (top surface) and sides of the chip facing away from the circuit board, thereby providing shielding for the chip from multiple directions and improving the shielding effect. Furthermore, the circuit board may include multiple chips, all disposed on the circuit board and located within a shielding cavity. When the metal layer also covers the sides of the chip, it also provides shielding between chips, preventing electromagnetic interference between chips.

[0011] In some embodiments of this application, the shielding structure overlaps at least one of the metal layer's surface away from the circuit board or the side of the metal layer at the cutout portion.

[0012] In one example, the shielding structure overlaps the metal layer at the cutout on the surface away from the circuit board. In this example, the projection of the cutout onto the metal layer is smaller than the metal layer itself. The metal layer's distance from the circuit board surface provides sufficient space for the shielding structure to overlap, resulting in a larger overlap area between the shielding structure and the metal layer, thereby improving overlap reliability.

[0013] In another example, the shielding structure overlaps the side of the metal layer at the cutout. Specifically, the cutout may surround the metal layer and be attached to and overlap the metal layer.

[0014] In another example, the shielding structure overlaps the surface of the metal layer away from the circuit board and the side of the metal layer at the cutout. This further increases the overlap area between the shielding structure and the metal layer, thereby improving the reliability of the overlap.

[0015] In some embodiments of this application, the shielding structure includes a shielding cover and a shielding film. The shielding cover is disposed on the circuit board and surrounds the chip. The shielding film has a cutout portion, and a portion of the shielding film overlaps with the surface of the shielding cover facing away from the circuit board. The shielding film overlaps with the metal layer at the cutout portion. That is, the shielding structure is a split structure. Due to manufacturing errors, the surface of the shielding cover facing away from the circuit board may be higher or lower than the surface of the metal layer facing away from the circuit board. When the shielding film is overlapped on the shielding cover and the metal layer, the manufacturing error can be absorbed by the deformation of the shielding film itself, thereby making the shielding film tightly adhere to the metal layer and tightly adhere to the shielding cover.

[0016] Regarding the structure of the shielding film, in one possible embodiment of this application, the shielding film includes a flexible metal layer and an adhesive layer stacked together. A portion of the adhesive layer connects the flexible metal layer and the shielding cover, while the adhesive layer connects the flexible metal layer and the metal layer at the perforated portions. The adhesive layer is typically a conductive adhesive, which also possesses a certain degree of flexibility. Furthermore, the perforated portions of the shielding film enhance its flexibility. Therefore, the shielding film comprising the flexible metal layer and the adhesive layer is a flexible film. Due to manufacturing errors, the shielding cover may be higher or lower than the surface of the metal layer facing away from the circuit board. When the shielding film is fixed to the metal layer and the shielding cover, the flexible shielding film can absorb manufacturing errors through its own deformation, thereby ensuring a tight fit between the shielding film and the metal layer, as well as a tight fit between the shielding film and the shielding cover.

[0017] In another possible embodiment of this application, the shielding film includes conductive adhesive. The conductive adhesive has both conductive and adhesive functions; a portion of the conductive adhesive can be adhered to the surface of the shielding cover facing away from the circuit board, and a portion can be adhered to the surface of the metal layer facing away from the circuit board. Furthermore, the conductive adhesive itself is a flexible structure, which can also absorb manufacturing errors through its own deformation, thereby achieving a better and tighter fit with both the metal layer and the shielding cover.

[0018] In some embodiments of this application, the metal layer includes a seed layer, a shielding layer, and a protective layer, sequentially stacked on the chip surface. The seed layer is located at the innermost edge of the metal layer, i.e., on the chip surface, and its main function is to improve the adhesion between the metal layer and the chip surface. The shielding layer is located in the middle layer of the metal layer, and its main function is to shield the chip. The protective layer is located at the outermost edge of the metal layer, and its main function is to prevent the shielding layer from being scratched or oxidized by direct contact with air.

[0019] In some embodiments of this application, the seed layer comprises stainless steel, the shielding layer comprises copper, and the protective layer comprises at least one of stainless steel or nickel. When the shielding layer comprises copper, the shielding effect of the shielding layer on the chip can be improved.

[0020] In a second aspect of this application, a method for manufacturing a circuit board assembly is also provided. This method can be used to manufacture circuit board assemblies according to any of the above embodiments. The method includes: covering a chip surface with a metal layer; placing the chip covered with the metal layer on a circuit board, with at least a portion of the metal layer located on the side of the chip facing away from the circuit board; placing a shielding structure on the circuit board, the shielding structure surrounding the chip, the shielding structure having a cutout portion, the shielding structure overlapping the metal layer at the cutout portion; placing a thermally conductive layer on the metal layer, with at least a portion of the thermally conductive layer located within the cutout portion; and placing a heat sink on the thermally conductive layer.

[0021] In this application, the circuit board, shielding structure, and metal layer can be combined to form a shielding cavity, and the chip is located inside the shielding cavity, thereby enabling the chip to be shielded.

[0022] Furthermore, a thermally conductive layer is located between the metal layer and the heat sink. A thermally conductive layer is placed between the metal layer and the heat sink, forming a thermally conductive interface between the metal layer and the thermally conductive layer, and another thermally conductive interface between the thermally conductive layer and the heat sink. In other words, two thermally conductive interfaces are formed between the metal layer and the heat sink. Since the metal layer covers the surface of the chip, the metal layer and the chip can be considered as a single unit for heat dissipation. Therefore, it can also be said that two thermally conductive interfaces are formed between the chip and the heat sink. This reduces the number of thermally conductive interfaces between the chip and the heat sink, thereby reducing the obstruction to heat dissipation and improving heat dissipation efficiency.

[0023] In addition, a metal layer and a thermally conductive layer are provided between the chip and the heat sink. Compared with the three-layer structure in related technologies, this application can reduce the number of structural layers between the chip and the heat sink, thereby reducing the distance between the chip and the heat sink and thus reducing the thickness of the entire circuit board assembly.

[0024] In a third aspect of this application, an electronic device is also provided, comprising: a circuit board assembly according to any of the above embodiments. The electronic device is capable of achieving all the effects of the circuit board assembly. Attached Figure Description

[0025] To illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.

[0026] Figure 1 This is a perspective view of an electronic device in an embodiment of this application when the electronic device is a mobile phone;

[0027] Figure 2 for Figure 1 The disassembled structure diagram of the electronic device shown;

[0028] Figure 3 This is a schematic diagram of the circuit board assembly in the related technology;

[0029] Figure 4 This is a schematic diagram of the circuit board assembly according to the first embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the circuit board assembly according to the second embodiment of this application;

[0031] Figure 6 This is a schematic diagram of the circuit board assembly according to the third embodiment of this application;

[0032] Figure 7 This is a schematic diagram of the circuit board assembly according to the fourth embodiment of this application;

[0033] Figure 8 This is a schematic diagram of the circuit board assembly according to the fifth embodiment of this application;

[0034] Figure 9 This is a schematic diagram of the circuit board assembly according to the sixth embodiment of this application;

[0035] Figure 10 for Figure 8 The diagram shows the deformation of the shielding film.

[0036] Figure 11 for Figure 9 The diagram shows the deformation of the shielding film.

[0037] Figure 12 for Figure 4 A flowchart illustrating the manufacturing process of the circuit board assembly shown.

[0038] Figure 13 for Figure 4 A schematic diagram of part of the manufacturing process of the circuit board assembly shown;

[0039] Figure 14 for Figure 4 A schematic diagram illustrating the fabrication process of the remaining parts of the circuit board assembly shown.

[0040] Icons: 1000 - Electronic device; 100 - Screen; 200 - Mid-frame; 300 - Back cover; 400 - Circuit board assembly; 410 - Circuit board; 411 - Shielding cavity; 420 - Chip; 421 - Surface; 422 - Side; 430 - Shielding structure; 431 - Cutout; 432 - Shielding cover; 4321 - Surface; 4322 - Cutout; 433 - Shielding film; 4331 - Flexible metal layer; 4332 - Adhesive layer; 4333 - Conductive adhesive; 434 - Dielectric layer; 440 - Thermally conductive layer; 450 - Heat sink; 460 - Metal layer; 461 - Surface; 462 - Side; 463 - Seed layer; 464 - Shielding layer; 465 - Protective layer; 500 - Camera. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0042] In this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can refer to a mechanical or physical connection. It can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. It can also be understood as the physical contact and electrical conduction of components, or as the form of connection between different components in a circuit structure through physical lines capable of transmitting electrical signals, such as PCB copper foil or wires.

[0043] This application provides an electronic device, which can be, for example, a server, consumer electronics, home electronics, in-vehicle electronics, financial terminal products, communication electronic products, etc., and this application does not limit the scope of the application. Indicatively, the aforementioned consumer electronics can be mobile phones, tablet computers, laptops, personal computers (PCs), personal digital assistants (PDAs), smart wearable products (e.g., smartwatches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, drones, etc. Home electronics can be smart door locks, televisions, smart speakers, refrigerators, robot vacuum cleaners, etc. In-vehicle electronic products can be in-vehicle navigation systems, in-vehicle displays, etc. Financial terminal products can be automated teller machines (ATMs), self-service electronic devices, etc. Communication electronic products can be servers, storage devices, radar, base stations, and other communication equipment.

[0044] This application does not impose any special limitations on the specific form of the above-described electronic device. For ease of explanation, the following description uses this electronic device as an example. Figure 1 The example shown is a mobile phone.

[0045] Please refer to Figure 1 and Figure 2 , Figure 1 A perspective view of a mobile phone provided in some embodiments of this application. Figure 2 for Figure 1 The diagram shows the disassembled structure of the electronic device 1000. The electronic device 1000 may include, for example... Figure 2 The screen 100, the middle frame 200, the back cover 300, and the circuit board assembly 400 fixed on the middle frame 200 are shown.

[0046] Understandable Figure 1 and Figure 2 The electronic device 1000 is shown only schematically, and the actual shape, size, location, and construction of these components are not subject to change. Figure 1 and Figure 2 The limitations. In some other examples, the electronic device 1000 may also not include the screen 100. Alternatively, the electronic device 1000 may also include, for example... Figure 2 The camera shown is 500.

[0047] Circuit board assemblies typically include electronic components such as chips, resistors, capacitors, and inductors. These components generate electromagnetic radiation noise during operation. This noise is received by the antenna in the electronic device, causing a deterioration in antenna sensitivity and consequently reducing communication quality. Therefore, electronic components that easily generate radiation noise need to be placed in a metal shielded cavity to isolate electromagnetic radiation noise.

[0048] like Figure 3 As shown, in related technologies, the circuit board assembly 400 includes a circuit board 410, a chip 420, a shielding structure 430, a thermally conductive layer 440, and a heat sink 450. The chip 420 is disposed on the circuit board 410, and the shielding structure 430 covers the chip 420. The shielding structure 430 and the circuit board 410 together form a shielding cavity 411, within which the chip 420 is located. A thermally conductive layer 440 is disposed between the shielding structure 430 and the chip 420, and another thermally conductive layer 440 is disposed between the heat sink 450 and the shielding structure 430. Therefore, there are two thermally conductive layers 440 and one shielding structure 430 between the chip 420 and the heat sink 450, totaling three layers.

[0049] On one hand, a thermal interface 'a' is formed between the chip 420 and the thermally conductive layer 440; another thermal interface 'a' is formed between the thermally conductive layer 440 near the chip 420 and the shield 432; another thermal interface 'a' is formed between the shield 432 and the thermally conductive layer 440 near the heat sink 450; and yet another thermal interface 'a' is formed between the thermally conductive layer 440 near the heat sink 450 and the heat sink 450. Therefore, a total of four thermal interfaces 'a' are formed between the chip 420 and the heat sink 450. In the process of transferring heat from the chip 420 to the heat sink 450 through the thermally conductive layer 440 near the chip 420, the shield 432, and the thermally conductive layer 440 near the heat sink 450, the heat needs to pass through four thermal interfaces 'a'. Each thermal interface 'a' will hinder heat dissipation to a certain extent; therefore, the heat dissipation efficiency in related technologies is relatively low.

[0050] On the other hand, because there is a three-layer structure between chip 420 and heat sink 450, the number of layers is relatively large, resulting in a large spacing d between chip 420 and heat sink 450, which in turn leads to a large thickness D of circuit board assembly 400. For example, the minimum thickness of thermal conductive layer 440 is 50um, and the minimum thickness of shielding cover 432 is 80um. Therefore, the minimum spacing d between chip 420 and heat sink 450 is 50×2+80=180um.

[0051] Based on this, this embodiment provides a circuit board assembly 400. The circuit board assembly 400 can improve heat dissipation efficiency and reduce the distance d between the chip 420 and the heat sink 450, thereby reducing the thickness D of the circuit board assembly 400.

[0052] like Figure 4 As shown, the circuit board assembly 400 includes a circuit board 410, a chip 420, a metal layer 460, a shielding structure 430, a thermally conductive layer 440, and a heat sink 450.

[0053] In this embodiment, the circuit board 410 can be a printed circuit board (PCB) or a flexible circuit board.

[0054] like Figure 4 As shown, chip 420 is disposed on circuit board 410. Circuit board assembly 400 may include one chip 420 or multiple chips 420. When circuit board assembly 400 includes one chip 420, the chip 420 is disposed on circuit board 410. When circuit board assembly 400 includes multiple chips 420, the multiple chips 420 are all disposed flat on circuit board assembly 400.

[0055] Chip 420 can be a pre-packaged functional module. For example, chip 420 can be a system-on-chip (SOC), a test or dummy chip, a central processing unit (CPU), a graphics processing unit (GPU), memory, an input / output (I / O) chip, an integrated passive device (IPD), etc. It can also integrate other pre-packaged functional modules, such as high-bandwidth memory (HBM), die-on-silicon interposer (DOI), fan-out RDL interposer (FOI), etc.

[0056] like Figure 4 As shown, the multiple chips 420 include a chip 420a that requires heat dissipation and a chip 420b that does not require heat dissipation. The chip 420a that requires heat dissipation can be a high-power chip, such as a computing chip, for example, a System-on-a-Chip (SoC). The chip 420b that does not require heat dissipation can be a low-power chip, such as a communication chip, for example, an I / O chip.

[0057] like Figure 4 As shown, the metal layer 460 at least covers the surface 421 of the chip 420 facing away from the circuit board 410. It can be understood that the metal layer 460 may cover the surface of the chip 420a that requires heat dissipation.

[0058] In one example, such as Figure 4 As shown, the metal layer 460 only covers the surface 421 of the chip 420a that is away from the circuit board 410.

[0059] In another example, such as Figure 5 As shown, the metal layer 460 covers the surface 421 and side surfaces 422 of the chip 420a opposite to the circuit board 410. Specifically, the chip 420a may include four side surfaces 422, and the metal layer 460 may cover some of the four side surfaces 422. For example, the metal layer 460 may cover one, two, or three side surfaces 422. Alternatively, the metal layer 460 may cover all four side surfaces 422, that is, the metal layer 460 covers all four side surfaces 422.

[0060] Thus, as Figure 5As shown, the metal layer 460 can shield the chip 420a from multiple directions, thereby improving the shielding effect of the chip 420a. Furthermore, when the circuit board assembly 400 includes multiple chips 420, the portion of the metal layer 460 covering the side 422 can also act as a shield between chips 420 and 420b, preventing chip 420a from causing electromagnetic interference to other chips 420b.

[0061] like Figure 4 As shown, a shielding structure 430 is disposed on the circuit board 410 and surrounds the chip 420a. The shielding structure 430 has a cutout portion 431, and the shielding structure 430 overlaps with the metal layer 460 at the cutout portion 431. Thus, the circuit board 410, the shielding structure 430, and the metal layer 460 can be combined to form a shielding cavity 411, in which the chip 420a is located, thereby shielding the chip 420a. It can be understood that when the circuit board assembly 400 includes multiple chips 420, all multiple chips 420 are located within the shielding cavity 411.

[0062] Regarding the overlapping method of the shielding structure 430 on the metal layer 460, in one example, such as Figure 4 and Figure 5 As shown, the shielding structure 430 overlaps the surface 461 of the metal layer 460 facing away from the circuit board 410 at the cutout portion 431. In this example, the projection of the cutout portion 431 onto the metal layer 460 is smaller than the metal layer 460. The surface 461 of the metal layer 460 facing away from the circuit board 410 provides sufficient space for the overlap of the shielding structure 430. Therefore, the overlap area between the shielding structure 430 and the metal layer 460 is large, thereby improving the reliability of the overlap.

[0063] In another example, such as Figure 6 As shown, the shielding structure 430 overlaps the side surface 462 of the metal layer 460 at the cutout portion 431. Specifically, the cutout portion 431 can surround the metal layer 460 and is attached to and overlaps the side surface 462 of the metal layer 460.

[0064] In yet another example, such as Figure 7 As shown, the shielding structure 430 overlaps with the surface 461 and side 462 of the metal layer 460 at the cutout portion 431. This further increases the overlap area between the shielding structure 430 and the metal layer 460, thereby improving the reliability of the overlap.

[0065] like Figure 4As shown, the thermally conductive layer 440 is located on the surface 461 of the metal layer 460 facing away from the chip 420a, and at least a portion of the thermally conductive layer 440 is located within the cutout portion 431. That is, a portion of the thermally conductive layer 440 is located within the cutout portion 431, and the remaining portion is located outside the cutout portion 431. For example, the remaining portion may be located on the side of the cutout portion 431 facing away from the circuit board 410. Alternatively, the entire structure of the thermally conductive layer 440 may be located within the cutout portion 431.

[0066] The material of the thermal conductive layer 440 may include thermally conductive materials, specifically thermally conductive silicone grease.

[0067] The heatsink 450 may include a vapor chamber, specifically a vacuum chamber (VC). Figure 4 As shown, the heat sink 450 is disposed on the heat-conducting layer 440. That is, the heat-conducting layer 440 is located between the metal layer 460 and the heat sink 450.

[0068] In one example, such as Figure 4 As shown, there is a gap between the heat sink 450 and the shielding structure 430. A portion of the heat-conducting layer 440 is located inside the cutout portion 431, and a portion is located on the side of the cutout portion 431 away from the circuit board 410.

[0069] In another example, there is no gap between the heat sink 450 and the shielding structure 430, and the entire structure of the heat-conducting layer 440 is located within the cutout portion 431.

[0070] like Figure 4 As shown, a thermally conductive layer 440 is disposed between the metal layer 460 and the heat sink 450. A thermally conductive interface 'a' is formed between the thermally conductive layer 440 and the metal layer 460, and another thermally conductive interface 'a' is formed between the thermally conductive layer 440 and the heat sink 450. In other words, two thermally conductive interfaces 'a' can be formed between the metal layer 460 and the heat sink 450. Since the metal layer 460 covers the surface 421 of the chip 420a, when the chip 420a dissipates heat, the metal layer 460 and the chip 420a can be considered as a whole for heat dissipation. Therefore, it can also be said that two thermally conductive interfaces 'a' are formed between the chip 420a and the heat sink 450. This reduces the number of thermally conductive interfaces 'a' formed between the chip 420a and the heat sink 450, thereby reducing the obstruction of heat dissipation by the thermally conductive interfaces 'a' and improving heat dissipation efficiency.

[0071] In addition, a metal layer 460 and a thermally conductive layer 440 are disposed between the chip 420a and the heat sink 450, compared to Figure 3The three-layer structure shown in the related technology reduces the number of structural layers between chip 420a and heat sink 450, thereby reducing the spacing d between chip 420a and heat sink 450, and consequently reducing the thickness D of the entire circuit board assembly 400. For example, the thickness of metal layer 460 is typically around 10µm, and the minimum thickness of shielding film 433 can be 50µm. When there is no gap between heat sink 450 and shielding structure 430, the spacing D between chip 420a and heat sink 450 is 10µm + 50µm = 60µm. When there is a gap between heat sink 450 and shielding structure 430, the size of this gap can be 10-20µm; therefore, the spacing D between chip 420a and heat sink 450 is 70-80µm. Figure 3 The minimum spacing D in the related technologies shown is 180 μm. It can be seen that the spacing D in this embodiment is smaller than that in the related technologies.

[0072] In some embodiments of this application, such as Figure 4 As shown, the shielding structure 430 can be a split structure. Specifically, the shielding structure 430 includes a shielding cover 432 and a shielding film 433 that are connected to each other.

[0073] like Figure 4 As shown, a shielding cover 432 is disposed on the circuit board 410 and surrounds chips 420a and 420b. The shielding cover 432 has a cutout portion 4322, at which it surrounds chip 420a, with a gap between the shielding cover 432 and chip 420a. The shielding cover 432 can be a rigid metal structure with a certain thickness. The material of the shielding cover 432 can include nickel-plated stainless steel or nickel plating, etc.

[0074] like Figure 4 As shown, the shielding film 433 has a cutout portion 431. Part of the shielding film 433 overlaps with the surface 4321 of the shielding cover 432 facing away from the circuit board 410. The shielding film 433 overlaps with the surface 461 of the metal layer 460 facing away from the circuit board 410 at the cutout portion 431. Thus, on the one hand, the shielding film 433 can be electrically connected to the shielding cover 432 and the metal layer 460 respectively, thereby forming a complete shielding cavity 411 together with the circuit board 410. On the other hand, the shielding cover 432 and the metal layer 460 can provide a certain degree of support for the shielding film 433.

[0075] Regarding the structure of the shielding film 433, in one possible implementation, such as Figure 4 As shown, the shielding film 433 includes a flexible metal layer 4331 and an adhesive layer 4332 stacked together. A portion of the adhesive layer 4332 is connected between the flexible metal layer 4331 and the shielding cover 432. The adhesive layer 4332 is connected between the flexible metal layer 4331 and the metal layer 460 at the hollow portion 431.

[0076] In one example, the flexible metal layer 4331 can be a metal foil, such as copper foil. Copper foil is typically thin, and when subjected to stress, it can undergo a certain degree of deformation, and is not easily damaged within the allowable deformation range.

[0077] In another example, the shielding film 433 can be a conductive cloth. The conductive cloth uses fiber cloth (commonly polyester fiber cloth) as the base material, which is pre-treated and then electroplated with a metal coating to give it metallic properties, thus becoming a conductive fiber cloth. The conductive part can be divided into: nickel-plated conductive cloth, gold-plated conductive cloth, carbon-plated conductive cloth, or aluminum foil fiber composite cloth, etc. The conductive cloth has a flexible structure and can undergo a certain degree of deformation under stress.

[0078] Adhesive layer 4332 is typically a conductive adhesive, thus possessing both conductive and adhesive functions. The material of adhesive layer 4332 can include epoxy resin, acrylic adhesive, or silicone. Since epoxy resin, acrylic adhesive, or silicone itself is not conductive, a conductive medium, such as mica or carbon black, can be added to the epoxy resin, acrylic adhesive, or silicone to achieve the conductivity of adhesive layer 4332.

[0079] The adhesive layer 4332 itself has a certain degree of flexibility. Furthermore, as... Figure 4 As shown, the shielding film 433 has a perforated portion 431, which further improves the flexibility of the shielding film 433. Therefore, the shielding film 433, including the flexible metal layer 4331 and the adhesive layer 4332, is a flexible film. Due to manufacturing errors, such as Figure 8 As shown, the shielding cover 432, facing away from the surface 4321 of the circuit board 410, may be higher than the metal layer 460, which faces away from the surface 461 of the circuit board 410. Or, as... Figure 9 As shown, the shielding cover 432 is away from the surface 4321 of the circuit board 410, and may be lower than the surface 461 of the metal layer 460 away from the circuit board 410. When the shielding film 433 is fixed on the metal layer 460 and the shielding cover 432, the shielding film 433, which has a certain degree of flexibility, can be deformed by itself (e.g., Figure 10 and Figure 11 (As shown) absorbs manufacturing errors, thereby ensuring that the shielding film 433 is tightly bonded to the metal layer 460 and to the shielding cover 432.

[0080] In another possible implementation, such as Figure 6As shown, the shielding film 433 includes conductive adhesive 4333. The conductive adhesive 4333 has both conductive and adhesive functions. A portion of the conductive adhesive 4333 can be adhered to the surface 4321 of the shielding cover 432 facing away from the circuit board 410, and a portion can be adhered to the surface 461 of the metal layer 460 facing away from the circuit board 410. Furthermore, the conductive adhesive 4333 itself is a flexible structure, which can also absorb manufacturing errors through its own deformation, thereby better and more tightly adhering to the metal layer 460 and the shielding cover 432 respectively.

[0081] The conductive adhesive 4333 can be made of epoxy resin, acrylic adhesive, or silicone. Since epoxy resin, acrylic adhesive, or silicone itself is not conductive, a conductive medium, such as mica or carbon black, can be added to the epoxy resin, acrylic adhesive, or silicone to achieve the conductivity of the adhesive layer 4332.

[0082] It is understandable that conductive adhesive 4333 can be applied to the shielding cover 432 and between the shielding cover 432 and the side 462 of the metal layer 460. The conductive adhesive 4333 is fluid before solidification. Therefore, to provide support for the conductive adhesive 4333, such as... Figure 6 As shown, the circuit board assembly 400 may further include a dielectric layer 434 located within a shielding cavity 411. A portion of the conductive adhesive 4333 is located on the surface 4321 of the shielding cover 432 facing away from the circuit board 410, and another portion is located on the dielectric layer 434 and overlaps with the side 462 of the metal layer 460.

[0083] In some embodiments of this application, such as Figure 4 As shown, the metal layer 460 may include a seed layer 463, a shielding layer 464, and a protective layer 465, which are sequentially stacked on the surface 421 of the chip 420a.

[0084] Among them, such as Figure 4 As shown, the seed layer 463 is located on the innermost side of the metal layer 460, that is, on the surface 421 of the chip 420a. Its main function is to improve the bonding force between the metal layer 460 and the surface 421 of the chip 420a. The seed layer 463 may include stainless steel.

[0085] like Figure 4 As shown, the shielding layer 464 is located in the middle layer of the metal layer 460, and its main function is to shield the chip 420a. The shielding layer 464 may include copper, thereby improving the shielding effect of the shielding layer 464 on the chip 420a.

[0086] like Figure 4As shown, the protective layer 465 is located on the outermost side of the metal layer 460, and its main function is to prevent the shielding layer 464 from being scratched or oxidized by direct contact with air. The protective layer 465 includes at least one of stainless steel or nickel. For example, the protective layer 465 includes stainless steel; or, the protective layer 465 includes nickel; or, the protective layer 465 includes both stainless steel and nickel.

[0087] This application also provides a method for manufacturing a circuit board assembly 400, which can be used to manufacture... Figure 4 The circuit board assembly 400 shown.

[0088] like Figure 12 The manufacturing method, as shown, includes:

[0089] S111, a metal layer is covered on the surface of the chip.

[0090] like Figure 13 As shown in (a), a metal layer 460 can be applied to the surface 421 of chip 420a using processes such as sputtering, electroplating, or electroless plating. When the metal layer 460 includes a seed layer 463, a shielding layer 464, and a protective layer 465, these layers can be sequentially applied to the surface 421. In this embodiment, the metal layer 460 may only cover one side surface 421 of chip 420a. When chip 420a is connected to circuit board 410 using a flip-chip packaging process, i.e., the front side of chip 420a faces circuit board 410, the metal layer 460 may be applied to the back side of chip 420a. In other embodiments, the metal layer 460 may cover both the back side and side 422 of chip 420a.

[0091] S112, placing the chip covered with a metal layer on the circuit board.

[0092] like Figure 13 As shown in (b), a chip 420a covered with a metal layer 460 can be mounted on a circuit board 410 by soldering. The metal layer 460 is located on the surface 421 of the chip 420a facing away from the circuit board 410. Alternatively, a chip 420b that does not require heat dissipation can also be mounted on the circuit board 410; that is, a chip 420b without a metal layer can be mounted on the circuit board 410.

[0093] S113, the shielding structure is placed on the circuit board.

[0094] The shielding structure 430 may include a shielding cover 432 and a shielding film 433, such as Figure 13 As shown in (c), the shield 432 can be first placed on the circuit board 410 by soldering, and the shield 432 surrounds the chip 420a and the chip 420b.

[0095] Next, as Figure 13 As shown in (d), the shielding film 433 is attached to the shielding cover 432 and the metal layer 460. The shielding film 433 has a cutout portion 431, and the shielding film 433 overlaps with the metal layer 460 at the cutout portion 431. The shielding film 433 also overlaps with the shielding cover 432.

[0096] The shielding film 433 may include a flexible metal layer 4331 and an adhesive layer 4332. The flexible metal layer 4331 may be first bonded to the adhesive layer 4332 to form the shielding film 433, and then the shielding film 433 may be attached to the shielding cover 432 and the metal layer 460. Alternatively, the adhesive layer 4332 may be first bonded to the shielding cover 432 and the metal layer 460, and then the flexible metal layer 4331 may be bonded to the adhesive layer 4332.

[0097] S114, a heat-conducting layer is provided on the metal layer.

[0098] Specifically, such as Figure 14 As shown in (a), a heat-conducting layer 440 may be disposed within a cutout 431 above the metal layer 460, with at least a portion of the heat-conducting layer 440 located within the cutout 431. For example, in this embodiment, a portion of the heat-conducting layer 440 is located within the cutout 431, while the remaining portion is located on the side of the cutout 431 facing away from the circuit board 410 and on the side of the shielding structure 430 facing away from the circuit board 410. In other embodiments, the entire structure of the heat-conducting layer 440 may be located within the cutout 431.

[0099] S115 places the heat sink on the thermally conductive layer.

[0100] The radiator 450 can be pre-set as follows: Figure 14 The heat sink 450 is mounted on the middle frame 200 as shown in (b). For example, the heat sink 450 is mounted on the middle frame 200 by means of welding or snap-fit. Then, the heat sink 450 can be placed on the thermally conductive layer 440, and the heat sink 450 and the metal layer 460 are connected through the thermally conductive layer 440 by extrusion.

[0101] In this embodiment, as Figure 14 As shown in (b), the circuit board 410, the shielding structure 430 and the metal layer 460 can be enclosed to form a shielding cavity 411, where chips 420a and 420b are located, thereby shielding chips 420a and 420b.

[0102] Moreover, such as Figure 14As shown in (b), the thermally conductive layer 440 is located between the metal layer 460 and the heat sink 450. That is, a thermally conductive layer 440 is disposed between the metal layer 460 and the heat sink 450. A thermally conductive interface a is formed between the thermally conductive layer 440 and the metal layer 460, and another thermally conductive interface a is formed between the thermally conductive layer 440 and the heat sink 450. In other words, two thermally conductive interfaces a can be formed between the metal layer 460 and the heat sink 450. Since the metal layer 460 covers the surface 421 of the chip 420a, when the chip 420a dissipates heat, the metal layer 460 and the chip 420a can be considered as a whole for heat dissipation. Therefore, it can also be said that two thermally conductive interfaces a are formed between the chip 420a and the heat sink 450. In this way, the number of thermally conductive interfaces a formed between the chip 420a and the heat sink 450 is reduced, thereby reducing the obstruction effect of the thermally conductive interfaces a on heat dissipation and improving heat dissipation efficiency.

[0103] In addition, such as Figure 14 As shown in (b), a two-layer structure, a metal layer 460 and a thermally conductive layer 440, is disposed between the chip 420a and the heat sink 450. Compared to Figure 3 The three-layer structure shown in the related technology can reduce the number of structural layers between chip 420a and heat sink 450 in this embodiment, thereby reducing the spacing d between chip 420a and heat sink 450, and thus reducing the thickness D of the entire circuit board assembly 400.

[0104] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A circuit board assembly, characterized in that, include: Circuit board; The chip is mounted on the circuit board; A metal layer, at least covering the surface of the chip facing away from the circuit board; A shielding structure is disposed on the circuit board and surrounds the chip. The shielding structure has a cutout portion, and the shielding structure overlaps with the metal layer at the cutout portion. A thermally conductive layer is located on the surface of the metal layer opposite to the chip, and at least a portion of the thermally conductive layer is located within the cutout portion; A heat sink is disposed on the thermally conductive layer.

2. The circuit board assembly according to claim 1, characterized in that, The metal layer also covers the sides of the chip.

3. The circuit board assembly according to claim 1 or 2, characterized in that, The shielding structure overlaps at the cutout portion on at least one of the surface of the metal layer facing away from the circuit board or the side of the metal layer.

4. The circuit board assembly according to any one of claims 1-3, characterized in that, The shielding structure includes: A shielding cover is disposed on the circuit board and surrounds the chip; The shielding film has the cutout portion, and a portion of the shielding film overlaps with the surface of the shielding cover opposite to the circuit board. The shielding film overlaps with the metal layer at the cutout portion.

5. The circuit board assembly according to claim 4, characterized in that, The shielding film includes a flexible metal layer and an adhesive layer stacked together. A portion of the adhesive layer is connected between the flexible metal layer and the shielding cover. The adhesive layer is also connected between the flexible metal layer and the metal layer at the hollowed-out portion.

6. The circuit board assembly according to claim 4, characterized in that, The shielding film includes conductive adhesive.

7. The circuit board assembly according to any one of claims 1-6, characterized in that, The metal layer includes a seed layer, a shielding layer, and a protective layer that are sequentially stacked on the surface of the chip.

8. The circuit board assembly according to claim 7, characterized in that, The seed layer comprises stainless steel, the shielding layer comprises copper, and the protective layer comprises at least one of stainless steel or nickel.

9. A method for manufacturing a circuit board assembly, characterized in that, The manufacturing method includes: Cover the surface of the chip with a metal layer; The chip covered with the metal layer is disposed on a circuit board, with at least a portion of the metal layer located on the side of the chip facing away from the circuit board; A shielding structure is placed on the circuit board, the shielding structure surrounds the chip, the shielding structure has a cutout, and the shielding structure overlaps with the metal layer at the cutout; A heat-conducting layer is disposed on the metal layer, and at least a portion of the heat-conducting layer is located within the hollow portion; The heat sink is placed on the thermally conductive layer.

10. An electronic device, characterized in that, include: The circuit board assembly according to any one of claims 1-8.

Images