A special-shaped heat dissipation cover and electronic device packaging structure and method

Abstract

The present application provides a special-shaped heat dissipation cover and an electronic device packaging structure and method, which are applied to the field of electronic device packaging technology. The heat dissipation cover extends a preset area at the corners around the support block at the bottom of the heat dissipation cover to the bottom center area of ​​the heat dissipation cover plate to form an extension arm to increase the structural strength and contact area, which can effectively disperse the stress; the extension arm, the support block and the heat dissipation cover body are made of the same high thermal conductivity material, such as copper, stainless steel or ceramic, to ensure excellent thermal conductivity performance; the inner surface of the heat dissipation cover is coated with a thermal interface material containing metal additives to further improve the thermal conductivity efficiency. The heat dissipation cover designs an extension arm at the maximum stress point to increase the tension of the heat dissipation cover on the four corners of the FCBGA packaging substrate, thereby improving the heat dissipation performance of the electronic device packaging, thereby improving the influence of the warping of the packaging substrate on the packaging, and increasing the stability of the packaging, which is suitable for the packaging needs of high-density electronic devices.

Description

Technical Field

[0001] The present application relates to the technical field of electronic device packaging, and in particular to a special-shaped heat dissipation cover and an electronic device packaging structure and method. Background Art

[0002] In the field of electronic device packaging, with the continuous advancement of technology, electronic devices are developing towards smaller size, higher density and more diversified functions. This trend leads to a further increase in the size of chips and packages. However, due to the increase in package size, the risk of heat dissipation and warping increases. In order to solve the above problems, a heat dissipation cover is connected to the chip through a thermal interface material, and the thermal interface material fills the gap between the heterogeneous interfaces to reduce the heat transfer contact resistance and provide an effective heat dissipation channel. However, there are often differences in the thermal expansion coefficients between the chip, the packaging substrate and the heat dissipation cover. These differences will cause deformation and warping in the subsequent assembly process, especially for large-sized packaging structures, which will aggravate the thermal expansion mismatch, which not only reduces the coverage of the heat dissipation cover and the thermal interface material, but also may cause delamination, especially at the four corners of the thermal interface.

[0003] Therefore, in order to solve the above problems, the existing solutions mainly focus on optimizing the glue dispensing method. For example, the existing technology (Chinese patent application document: CN117524885A) optimizes the glue striping process to apply glue at the four corners of the FCBGA (Flip Chip Ball Grid Array) package substrate to reduce the stress at the four corners of the FCBGA package substrate. Although the existing technical solution can increase the connection strength to a certain extent, the solution has some technical defects, such as: the strength of the heat dissipation glue is limited, the process requirements are more, the glue is easy to overflow, and there is a risk of scratching the chip during the glue striping process.

[0004] Based on this, a new heat dissipation cover and electronic device packaging structure are needed. Summary of the invention

[0005] In view of this, the embodiments of this specification provide a special-shaped heat dissipation cover and an electronic device packaging structure and method, which can effectively solve the problem of degradation or even delamination of the edge of the thermal interface material caused by warping of large-sized chips and heat dissipation covers, resulting in reduced heat dissipation.

[0006] The embodiments of this specification provide the following technical solutions:

[0007] A special-shaped heat dissipation cover, comprising a heat dissipation cover plate and a support block arranged at the bottom of the heat dissipation cover plate;

[0008] The support block is arranged in a rectangular shape around the central area of ​​the bottom of the heat dissipation cover plate, and extends inwards at the four corners of the rectangular support block to form an extension arm, and the extension arm and the support block are arranged in an integral manner;

[0009] The extension arms are located inside the four corners of the inner surface of the heat dissipation cover, and the bottom of the heat dissipation cover is fixedly connected to the upper surface of the packaging substrate to form a stress dispersion structure.

[0010] Preferably, the support block and the heat dissipation cover plate are integrally formed to form a heat dissipation cover to form an integrated heat dissipation structure, and a thermal interface material is coated on the contact surface between the inner surface of the heat dissipation cover and the chip to reduce contact thermal resistance and further improve heat conduction efficiency.

[0011] In addition, by adjusting the packaging structure, an extension arm is added to the support block on the inner surface of the heat dissipation cover to enhance the overall rigidity, thereby improving the heat dissipation efficiency and reducing the warping phenomenon caused by the mismatch of thermal expansion coefficients.

[0012] Preferably, through structural optimization, extension arms are extended from the inner sides of the four corners of the support block on the inner surface of the heat dissipation cover. These extension arms provide additional pulling force at the points with the greatest stress to increase the pulling force of the heat dissipation cover on the four corners of the packaging substrate, effectively alleviating the warping problem caused by thermal expansion mismatch.

[0013] Preferably, the design of the extension arm improves the deformation of the four corners of the chip by increasing the contact area between the heat sink cover and the packaging substrate, increases the pulling force of the heat sink cover on the four corners of the packaging substrate, relieves product stress concentration, improves the degree of degradation of the thermal interface material, and prevents the thermal conductive adhesive from causing the interface to separate due to excessive deformation of the four corners of the chip, resulting in a decrease in coverage, that is, the coverage of the heat sink cover and the thermal interface material is reduced.

[0014] Preferably, the heat dissipation cover is made of copper, stainless steel or ceramic material with excellent thermal conductivity to ensure that heat can be quickly transferred from the chip to the heat dissipation cover.

[0015] Preferably, between the heat dissipation cover and the chip, an epoxy resin-based thermal conductive adhesive containing silver or copper additives or an indium sheet is used as a thermal interface material. These materials not only reduce the contact thermal resistance, but also play a role in bonding and fixing.

[0016] Preferably, during the packaging assembly process, the heat dissipation cover is connected to the packaging substrate through AD glue with high bonding strength, ensuring good bonding performance under various temperature conditions. The chip is installed on the packaging substrate through Bump flip-chip technology. Bump is a process in integrated circuit manufacturing. Bump is a process that connects the exposed metal leads of the integrated circuit to the metal bumps on the ceramic substrate. Through this connection method, the electrical and mechanical connection between the integrated circuit and the substrate can be achieved, thereby improving the reliability and performance of the circuit, and the electrical connection is completed through high-temperature reflow soldering.

[0017] In addition, Underfill is a process for sealing and filling the bottom solder joints. It mainly uses non-contact jet dispensing to perform bottom filling. Underfill is used to fill the gap between the chip and the packaging substrate to improve the bonding strength.

[0018] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0019] The technical solution increases the contact area between the heat dissipation cover and the FCBGA package substrate by adding extension arms on the inner sides of the four corners of the heat dissipation cover to form reinforcing ribs with a larger contact area, thereby increasing the pulling force of the heat dissipation cover on the four corners of the FCBGA package substrate, so that the stress between the chip and the heat dissipation cover, especially the contact stress between the four corners of the chip and the heat dissipation cover, is dispersed, thereby alleviating the stress on the four corners of the chip, especially the stress caused by the difference in thermal expansion coefficients, that is, the concentrated stress caused by the different thermal expansion coefficients between the heterogeneous interfaces can be dispersed, the warping phenomenon is reduced, and the problem of edge degradation and even delamination of the thermal interface material is well solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of a conventional heat dissipation cover in this application;

[0022] Figure 2 It is a schematic diagram of a special-shaped heat dissipation cover in this application;

[0023] Figure 3 It is a top view of a special-shaped heat dissipation cover in this application;

[0024] Figure 4It is a schematic diagram of the packaging structure of a special-shaped heat dissipation cover in this application;

[0025] Figure 5 It is a schematic diagram of the degree of degradation of the thermal interface material at the four corners of the edge of a conventional heat dissipation cover packaging structure in the present application;

[0026] Figure 6 It is a schematic diagram of the degree of degradation of the thermal interface material at the four corners of the edge of a special-shaped rib heat dissipation cover packaging structure in this application;

[0027] in:

[0028] 1. Heat dissipation cover; 2. Heat dissipation cover plate; 3. Support block; 4. Extension arm; 5. Package substrate; 6. Chip; 7. Thermal interface material; 8. AD glue; 9. Underfilled; 10. BGA. DETAILED DESCRIPTION

[0029] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0030] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0031] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0032] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0033] Furthermore, in the following description, specific details are provided to facilitate a thorough understanding of the examples.

[0034] As the integration of chips continues to increase, the power consumption and heat generation of chips also increase. Therefore, the chip heat dissipation problem has become one of the key factors restricting the performance improvement of electronic devices.

[0035] Currently, heat dissipation covers have been widely used in FCBGA structure packaging.

[0036] However, due to the differences in thermal expansion coefficients among the chip, packaging substrate and heat sink cover, deformation and warping are prone to occur in the packaging structure, which in turn causes degradation of the thermal interface material between the chip and the heat sink cover, resulting in uneven contact between the heat sink cover and the chip, reducing the heat dissipation effect.

[0037] Secondly, the large size of the heat sink cover is prone to stress concentration during the assembly process, especially at the edges and corners of the heat sink cover, which may cause degradation or even delamination of the thermal interface material, further reducing the heat dissipation performance.

[0038] In order to solve the above problems, since the coverage of thermal interface materials is the main factor affecting heat dissipation, the existing research directions are generally as follows: some studies focus on optimizing the performance of thermal interface materials, such as developing new thermal interface materials with higher thermal conductivity and better thermal stability. The chip and the heat dissipation cover are connected by thermal interface materials. The thermal interface materials are used to fill the gaps between heterogeneous interfaces and surface microgrooves to reduce heat transfer contact resistance and provide effective heat dissipation channels; other studies are committed to improving the packaging structure design, such as improving heat dissipation efficiency and structural stability by adjusting the shape of the heat dissipation cover or adding auxiliary structures.

[0039] refer to Figure 1 As shown in the figure, a heat sink cover is usually used in the existing packaging structure, that is, a concave heat sink area is formed in the central area of ​​the heat sink cover, and a supporting area is formed around the heat sink cover, wherein a thermal interface material is filled between the chip and the concave heat sink area of ​​the heat sink cover to realize heat conduction, and the heat sink cover support area is bonded and fixed to the packaging substrate, and then after bonding and fixing, the concave heat sink area of ​​the heat sink cover can press the chip and the thermal interface material, so that the thermal interface material can cover the top of the chip for as long as possible.

[0040] However, the large-size packaging structure using the above-mentioned heat dissipation cover will aggravate deformation and warping under high temperature. Even after high-temperature reflow soldering of the chip and long-term high-temperature storage testing, the four corners of the edge of the thermal interface material will be significantly degraded.

[0041] Therefore, although the existing heat dissipation cover packaging solution can improve the chip heat dissipation problem to a certain extent, it still has some limitations and cannot solve the heat dissipation and warping problems of large-size chips.

[0042] In addition, some existing technologies provide solutions to optimize the glue striping process (such as Chinese patent application: CN117524885A), that is, glue is applied at the four corners of the FCBGA package substrate (Dot), so as to reduce the stress at the four corners of the FCBGA package substrate in turn. Although this process increases the connection strength to a certain extent, the strength of the heat dissipation glue is limited, and the process requirements are relatively high. The glue is prone to overflow at the glue point, and a glue striping process is required. In addition, there is also a risk of scratching the chip during the glue striping process.

[0043] In summary, under the above research background, in-depth analysis and improvement exploration were carried out on the heat sink cover and packaging structure, and it was found that the traditional heat sink cover is prone to concentrated stress after packaging, especially at the edges and corners of the heat sink cover that are in contact with the chip, and these stresses should be the main reason for the degradation or even delamination of the thermal interface material.

[0044] Based on the above analysis, further in-depth analysis of the thermal interface material area inside the packaging structure is carried out. Figure 5 As shown in the figure, after reflow soldering (ball mounting), the thermal interface under the heat sink is not significantly degraded, probably because the time and number of thermal stress in reflow soldering are less, that is, the right-angle shape can be basically retained (see Figure 5 (a) The box in the figure shows the part), but after the high temperature storage life test (HTSL), such as the high temperature 150°, 500h test, after being subjected to multiple thermal stresses, the thermal interface material at the four corners where the heat sink and the chip meet has obviously degraded and has basically degenerated into a rounded shape (see Figure 5 (b) The box-illustrated part) may even delaminate, resulting in a significant decrease in the coverage of the thermal interface material.

[0045] Therefore, this technical solution proposes a new type of special-shaped heat sink cover design and its application in the FCBGA packaging structure. This solution effectively increases the pulling force of the heat sink cover on the packaging substrate by adding extension arms on the four corners of the heat sink cover to form reinforcing ribs, alleviates product stress concentration, and improves the degree of degradation of the thermal interface material, thereby significantly improving the heat dissipation performance and the stability of the packaging structure.

[0046] The technical solutions provided by various embodiments of the present application are described below in conjunction with the accompanying drawings.

[0047] like Figure 2 As shown, the heat dissipation cover 1 is composed of a heat dissipation cover plate 2 and support blocks 3 arranged around the bottom of the heat dissipation cover plate 2. The special-shaped heat dissipation cover design and packaging structure application are applied by adding extension arms 4 on the inner sides of the four corners of the heat dissipation cover 1. The extension arms 4 are equivalent to adding four reinforcing ribs on the inner sides of the four corners of the heat dissipation cover 1. In this way, the tension on the four corners of the FCBGA substrate can be increased at the maximum stress point. The heat dissipation cover 1 is used for heat dissipation and packaging of the chip 6 to improve the reliability and durability of the product.

[0048] Specifically, the heat dissipation cover 1 includes a heat dissipation cover plate 2 and support blocks 3 arranged around the bottom of the heat dissipation cover plate 2. The bottom center area of ​​the heat dissipation cover plate 2 is used to contact the chip 6. The heat dissipation cover plate 2 is used for heat conduction and heat dissipation of the chip 6.

[0049] In addition, the support block 3 is arranged in a rectangular shape around the bottom center area of ​​the heat dissipation cover plate 2, and a preset area is extended from the corners around the support block 3 to the bottom center area of ​​the heat dissipation cover plate 2 to form an extension arm 4. The extension arm 4 and the support block 3 are used together to bond with the packaging substrate 5 to increase the pulling force of the heat dissipation cover 1 on the four corners of the packaging substrate to disperse the contact stress between the heat dissipation cover plate 2 and the chip 6.

[0050] In addition, the extension arms 4 are located on the inner side of the four end corners of the inner surface of the heat dissipation cover 4. The extension arms 4 provide additional pulling force at the point where the stress is maximum, thereby enhancing the overall mechanical strength of the support block 3, especially when subjected to stress caused by thermal cycling. Since the corners of the support block 3 are areas where stress is concentrated, these extension arms 4 can disperse and absorb stress and enhance structural stability, thereby effectively alleviating the warping problem caused by thermal expansion mismatch and reducing the warping or deformation of the support block 3.

[0051] In addition, the design of the extension arm 4 not only takes into account the mechanical properties of stress, but also takes into account heat transfer management. The bottom of the heat dissipation cover 1 is fixedly connected to the upper surface of the packaging substrate 5 to form a stress dispersion structure. At the same time, the heat dissipation cover 1 is covered above the chip 6. The close contact of the extension arm 4 increases the contact area between the support block 3 and the packaging substrate 5, thereby improving the heat conduction efficiency.

[0052] In general, the design of the extension arm 4 not only enhances the connection strength between the heat dissipation cover 1 and the packaging substrate 5, but also increases the contact area and evenly distributes the stress, allowing heat to be more evenly transferred from the chip 6 to the heat dissipation cover 1 and then dissipated into the surrounding environment, effectively reducing the temperature of the hot spot area, thereby improving the heat dissipation performance.

[0053] In some embodiments, the support block 3 and the heat dissipation cover plate 2 are integrally formed to form the heat dissipation cover 1. The heat dissipation cover plate 2 and the support block 3 are manufactured as a heat dissipation cover 1 as a whole, which helps to improve the heat dissipation efficiency and the overall stability of the structure. The support block 3 and the heat dissipation cover plate 2 are integrally formed, and there is no seam or connection point between the extension arm 4 and the heat dissipation cover plate 2, which eliminates the thermal resistance and potential failure points that may be introduced by traditional connection methods. The extension arm 4 is generally designed to be distributed along the edge of the heat dissipation cover or the key stress area to maximize its contribution to the overall structural strength.

[0054] Specifically, the extension arm 4 serves as a mechanical support structure, which is integrated to improve the resistance of the packaged chip 6 to external impact and vibration, maximize the heat dissipation efficiency within a limited packaging space, and does not interfere with other components or circuits.

[0055] At the same time, the arrangement of the extension arms 4 at the four corners of the chip 6 helps to reduce the thermal stress generated by the chip 6 during operation, evenly distributes and reduces stress concentration points, and compensates for the expansion or contraction of the chip 6 and the package cover 1 under temperature changes.

[0056] At the same time, the one-piece heat sink cover 1 design can reduce connection points, reduce manufacturing costs, and may improve the mechanical strength and durability of the heat sink cover 1. When the one-piece design of the heat sink cover 1 uses materials with excellent thermal conductivity, such as copper, stainless steel or ceramic materials, better heat conduction can be achieved.

[0057] In some embodiments, the extension arm 4 is in an oblique angle shape, the distal end of the extension arm 4 is in an arc shape, and the proximal end of the extension arm connected to the edge of the support block 3 is in an arc shape. By designing the extension arm to be oblique and arc-shaped, the contact area between the heat dissipation cover and the packaging substrate is increased, the overall stability of the structure is improved, and the structural strength is enhanced.

[0058] Specifically, the extension arm 4 is designed to extend inward from the four corners of the support block 3 to form a concave structure. The optimized support block structure not only provides additional mechanical support, but also enhances the stability of the support block.

[0059] In some embodiments, both the distal end and the proximal end of the extension arm 4 are semicircular arcs. The concave design of the semicircular arc of the extension arm 4 allows the support block 3 to have greater flexibility at the corners, increasing the effective heat conduction path, while improving the heat conduction efficiency and the overall heat dissipation performance in the design of the heat sink 1.

[0060] In addition, the extension arm 4 is designed at the stress concentration area of ​​the heat dissipation cover 1, such as the edge or corner, to improve the structural strength and stability. The shape and size of the extension arm 4 are optimized according to the size of the heat dissipation cover 1 and the expected load.

[0061] It should be noted that the support block 3 on the inner surface of the heat dissipation cover 1 is in direct contact with the heat source of the chip 6. In order to cope with thermal expansion and mechanical stress, the heat dissipation cover 1 is designed with stress release structures, such as micropores and grooves, to absorb and disperse stress. It is usually designed to be as smooth as possible to ensure good heat conduction.

[0062] In some embodiments, the heat dissipation cover 1 is a structure made of a high thermal conductivity material, wherein the thermal conductivity material includes any one of the following materials: copper, aluminum, stainless steel or ceramic, to achieve efficient heat conduction. The heat dissipation cover 1 covers the top of the chip, and its shape and size are customized according to the requirements of the chip and application to achieve higher heat conduction efficiency.

[0063] Specifically, the high thermal conductivity material on the surface of the heat dissipation cover 1, copper has extremely high thermal conductivity, stainless steel has good corrosion resistance and structural strength, and ceramics have high thermal conductivity and high temperature resistance, which not only ensures that heat can be quickly transferred from the chip 6 to the heat dissipation cover 1, but also improves the thermal response speed of the entire packaging structure. Through the use of high thermal conductivity materials, the heat dissipation cover 1 can evenly diffuse heat when the surface is exposed to high heat loads. The application of high thermal conductivity materials allows the heat dissipation cover 1 and the support block 3 to quickly absorb heat from the heat source. Copper and aluminum are ideal heat dissipation materials due to their high thermal conductivity coefficients, and can efficiently transfer heat from the chip to the heat dissipation structure and ultimately disperse it into the environment.

[0064] In addition, the extension arm 4, as a part of the heat dissipation cover 1, is also made of high thermal conductivity material, which not only enhances the structural strength of the heat dissipation cover 1, but also increases the efficiency of heat conduction by increasing the contact area between the heat dissipation cover 1 and the packaging substrate 5, thereby reducing thermal stress and avoiding deformation of the packaging structure caused by temperature changes.

[0065] In addition, the heat dissipation cover plate 2, the support block 3 and the extension arm 4 are integrally formed to form the heat dissipation cover 1, and the surface of the heat dissipation cover 1 is specially treated, such as anodizing, plating or coating with high emissivity materials, which helps to improve the durability and stability under high temperature regulation.

[0066] During the packaging assembly process, the four extension arms 4 increase the connectivity between the packaging substrate 5 and the heat dissipation cover 1, thereby improving the impact of the warping of the packaging substrate 5 on the packaging, increasing the stability and impact resistance of the packaging, and thus increasing the reliability of the product.

[0067] like Figure 3 As shown, the extension arm 4 enhances the stability and heat dissipation efficiency of the overall structure. The extension arm 4 not only provides additional structural support and reduces deformation caused by thermal expansion, but also serves as an additional heat conduction path to improve the efficiency of dispersing and transferring heat.

[0068] In some embodiments, the heat dissipation cover 1 is fixedly connected to the packaging substrate 5, and the setting of the extension arm can evenly distribute the stress between the heat dissipation cover 1 and the packaging substrate 5. The heat dissipation cover 1 and the support block 3 are made of materials with the same thermal expansion coefficient to ensure that the thermal expansion between the extension arm 4 and the heat dissipation cover 1 matches when the temperature changes.

[0069] In addition, by buckling the chip 6 into the support block 3 in the heat dissipation cover 1 , additional rigidity is provided to prevent the corner area of ​​the chip 6 from warping or deformation due to thermal expansion or mechanical stress.

[0070] An electronic device packaging structure, such as Figure 4 As shown in the figure, the electronic device packaging structure includes a packaging substrate 5, a heat dissipation cover 1 and a chip 6. The thermal interface material 7 is evenly coated or filled on the chip 6 and the inner surface of the heat dissipation cover 1. The chip 6 is mounted on the upper surface of the packaging substrate 5 and is flip-chip mounted on the packaging substrate 5 through the flip-chip technology. The electrical connection between the chip 6 and the packaging substrate 5 is completed through high-temperature reflow soldering.

[0071] Specifically, in the electronic device packaging process, accurately placing and fixing the chip 6 on the packaging substrate 5 is a key step. The packaging substrate 5 and the chip 6 are flipped on the packaging substrate 5 using the flip chip technology, and then the chip 5 is mounted on the packaging substrate 5 by high-temperature reflow soldering to achieve electrical connection. The process first involves an electronic device chip with multiple electrical connection points, which will be used to establish electrical connection with an external circuit.

[0072] In addition, a thermal interface material 7 is coated between the surface of the chip 6 and the heat dissipation cover 1, and the heat dissipation cover 1 is bonded and fixed to the packaging substrate 5. The bonding and fixing of the heat dissipation cover 1 and the packaging substrate 5 ensures the stability of the electronic device packaging structure and the heat dissipation performance.

[0073] In some embodiments, the inner surface of the heat dissipation cover 1 is connected to the upper surface of the chip 6 through the thermal interface material 7. The chip 6 is flipped on the upper surface of the packaging substrate 5 through the flip-chip technology. The bottom of the packaging substrate 5 is provided with a ball grid array packaging solder joint. The flip-chip design can be used to directly connect the support block 3 to the chip 6 to achieve better heat dissipation.

[0074] Specifically, the flip-chip technology allows the chip 6 to be installed face down, so that the pins of the chip 6 are in direct contact with the packaging substrate 5, and the chip 6 is precisely aligned with the corresponding pads on the packaging substrate 5 to ensure that the chip 6 is aligned with the pads on the packaging substrate 5, so that the chip 6, the heat dissipation cover 1 and the packaging substrate 5 are packaged into one to form a packaging structure, which can reduce the occupied space and achieve a higher packaging density. The connection between the flip-chip chip 6 and the packaging substrate 5 uses a high-strength conductive adhesive, which provides good mechanical stability.

[0075] In addition, chip 6 is a flip chip ball grid array chip, and ball grid array packaging solder joints are set at the bottom of the packaging substrate 5. Chip 6 is flipped on the packaging substrate 5 through flip chip technology, wherein the flip chip technology includes forming solder joints on the surface of the chip and electrically connecting them with corresponding pads on the packaging substrate. The ball grid array packaging solder joints are used for electrical connection between the packaging substrate 5 and the PCB board.

[0076] In addition, a thermal interface material 7 is coated on the inner surface of the heat dissipation cover 1 and above the chip 6. The thermal interface material 7 is selected from a material that can improve the heat conduction efficiency. Then, the heat dissipation cover 1 with the extension arm 4 is installed above the chip 6. The heat dissipation cover 1 is connected to the packaging substrate 5 by AD glue 8. The AD glue 8 is selected from a material that can remain stable under thermal cycles.

[0077] In addition, the gap between the chip 6 and the packaging substrate 5 is filled with Underfill, so that the heat dissipation cover 1 and the packaging substrate 5 encapsulate the chip 6 inside as a whole, forming an electronic device packaging structure. Before the support block is mounted, the chip 6 is flipped on the upper surface of the packaging substrate 5 through Bump. The Bump flip technology allows the chip 6 to be installed above the packaging substrate 5, and the back side can be exposed to the outside for easy heat dissipation, which helps to improve the heat conduction efficiency. After high-temperature reflow, the electrical connection between the chip 6 and the packaging substrate 5 is completed to provide electrical connection.

[0078] In some embodiments, BGA (Ball Grid Array) is an interconnection technology widely used in electronic packaging, which provides an electrical interconnection channel between the packaging substrate 5 and the PCB. BGA uses an array of spherical solder joints to achieve interconnection, and these spherical solder joints are distributed on the bottom or surface of the packaging substrate.

[0079] Specifically, an electrical interconnection channel is a conductive path used to transmit electrical signals or power in an electronic device. In electronic packaging and printed circuit board (PCB) design, the realization of electrical interconnection channels is crucial, as they ensure effective electrical connections between electronic components.

[0080] Each spherical solder joint corresponds to a pad on the PCB. The bottom of the package structure includes BGA solder joints. When the BGA package substrate is aligned with the PCB and appropriate pressure and temperature are applied, the spherical solder joints melt and form an electrical connection. Since BGA solder joints are usually made of materials with good thermal conductivity, they can also help dissipate heat to a certain extent, conducting heat from the package substrate to the PCB.

[0081] BGA provides an electrical interconnection channel between the package substrate 5 and the PCB. In PCB design, the electrical interconnection channel appears in the form of lines, which connect different components and circuit nodes. BGA adopts a structure that hides circular or columnar points under the package, with large lead spacing and short lead length, eliminating the warping defects caused by lead problems in fine pitch devices.

[0082] At the same time, the electrical interconnection channel is connected to the pins or BGA solder joints of the electronic components through the pads to achieve electrical connection. The chip is connected to the package substrate, and the electrical connection between the chip 6 and the package substrate 5 is achieved. The chip 6 is mounted on the top surface of the package substrate 5 carrier. The heat dissipation cover 1 is welded on the package substrate 5 with sealing solder to protect the chip 6. The connected package body is treated with airtightness to improve its reliability and physical protection performance.

[0083] The chip 6 is mounted on the package substrate 5 through high-temperature reflow soldering. Through the thermal reflow soldering process, the chip 6 is combined with the pads on the package substrate 5 to form a stable electrical connection, while ensuring the mechanical strength of the connection point to achieve electrical connection.

[0084] Next, underfill material is injected between the chip 6 and the packaging substrate 5 to improve the mechanical stability of the structure and prevent damage due to thermal expansion or mechanical vibration. The heat dissipation cover 5 is aligned with the chip 6 and placed in place. The inner surface of the heat dissipation cover 1 is coated with a thermal interface material 7 to improve the heat conduction efficiency. The heat dissipation cover 1 with the extension arm 4 is placed above the chip 6. The thermal interface material 7, such as thermal conductive glue or indium sheet, is applied between the chip 6 and the heat dissipation cover 1 to fill the microscopic gaps and reduce the contact thermal resistance.

[0085] In some embodiments, the thermal interface material 7 includes one or more of the following materials: an epoxy resin-based thermal conductive adhesive with silver and / or copper as additives or an indium sheet as the thermal interface material 7. In addition to reducing the contact thermal resistance, the thermal interface material 7 can also structurally bond and fix the chip 6 and the heat sink cover 5.

[0086] At the same time, a certain amount of pressure needs to be applied during the installation process to ensure that the thermal interface material fills the gaps in all contact surfaces. The gaps between the chip and the packaging substrate are filled at the bottom by dispensing glue, and then the heat sink cover is accurately aligned with the chip and placed in the appropriate position. Gravity or moderate pressure is used to make the heat sink cover closely contact with the chip surface, and the heat sink cover and the packaging substrate are installed together to encapsulate the chip inside, ensuring that the extended arm features of the heat sink cover are completely matched with the shape of the chip. The heat sink cover is installed directly above the chip, and the high thermal conductivity of the thermal interface material is used to conduct heat from the heat source to the heat sink cover to form an integrated packaging structure.

[0087] In some embodiments, during the packaging assembly process, the heat dissipation cover 1 and the packaging substrate 5 are bonded and fixed by AD glue. The bottom of the heat dissipation cover 1 is bonded to the upper surface of the packaging substrate by AD adhesive with high bonding strength. The adhesive is an adhesive such as thermally conductive adhesive or thermally conductive epoxy resin. The gap between the chip 6 and the packaging substrate 5 is filled by a bottom filling process, and the bottom of the heat dissipation cover is connected to the packaging substrate. The contact area with the packaging substrate is increased by an extension arm to improve the connection stability. The adhesive not only plays a fixing role, but also can fill the tiny gaps between the contact surfaces, thereby improving the heat conduction efficiency, ensuring that good bonding performance can be maintained under various temperature conditions to improve the overall connection stability.

[0088] It should be noted that the heat dissipation cover 1 and the packaging substrate 5 are bonded and fixed with AD glue 8. The AD glue 8 is an adhesive with high bonding strength and good thermal stability, which can maintain bonding performance in a high temperature environment, thereby ensuring a long-term stable connection between the heat dissipation cover 1 and the packaging substrate 5. At the same time, the arrangement of the extension arm 4 on the heat dissipation cover plate 2 can ensure a firm connection between the heat dissipation cover 1 and the packaging substrate 5.

[0089] In some embodiments, the thickness and cross-sectional shape of the heat dissipation cover 1 affect its mechanical strength and thermal conductivity. The inner surface of the heat dissipation cover 1 body is designed with a micro-groove structure, such as micro-grooves or micro-bumps. After the thermal interface material 7 is applied to the inner surface of the heat dissipation cover, it is bonded and fixed to the upper surface of the chip 6 to increase the contact area with the thermal interface material 7, further improve the thermal conduction efficiency, and reduce the contact thermal resistance.

[0090] Specifically, the inner surface of the heat dissipation cover 1 is designed with a micro-groove structure, which not only increases the surface area of ​​the heat dissipation cover, but also provides surface conditions for the application of the thermal interface material 7. The thermal interface material 7 coated in the micro-groove can achieve effective thermal connection between the chip 6 and the heat dissipation cover 1, and the thermal interface material 7 has high thermal conductivity, can fill the micro-groove and adapt to the microscopic unevenness of the surface of the chip 6. The thermal interface material 7 is coated in the micro-groove of the inner surface of the heat dissipation cover 1 to form a layer of uniform heat transfer medium, which significantly reduces the contact thermal resistance and improves the heat dissipation efficiency of the chip 6.

[0091] In some embodiments, the thermal interface material is used to fill the gap between the chip and the heat dissipation cover to improve the heat conduction efficiency and reduce the contact thermal resistance. The thermal interface material includes high thermal conductivity metal additives such as silver and copper. These additives are evenly dispersed in the epoxy resin base to form a highly efficient thermal conductive adhesive.

[0092] Specifically, the thermal interface material 7 uses an epoxy resin-based thermal conductive adhesive with silver and copper as additives. Silver and copper have good thermal conductivity and are dispersed in the epoxy resin base in the form of particles or flakes, which increases the overall thermal conductivity of the material while maintaining the adhesive properties and flexibility of the resin.

[0093] In addition, the epoxy resin substrate itself has good adhesion, electrical insulation and mechanical stability, making it an ideal choice for making thermal interface materials. When metal additives such as silver and copper are added, it not only improves thermal conductivity, but also enhances the durability of the material under thermal cycles, ensuring long-term and reliable thermal management performance.

[0094] In addition to the form of thermal conductive adhesive, the thermal interface material 7 also adopts the form of indium sheet. The indium sheet has high ductility and plasticity, and can fill the microscopic unevenness of the contact surface under pressure to achieve a closer contact, thereby reducing the contact thermal resistance and improving the heat conduction efficiency.

[0095] In some embodiments, the local thickness of the connection between the extension arm 4 and the heat dissipation cover 1 is enhanced by a special molding process at the connection. The local thickness enhancement at the connection makes the transition area between the extension arm and the heat dissipation cover stronger and can withstand greater mechanical and thermal stresses.

[0096] Specifically, at the connection between the extension arm 4 and the heat dissipation cover 1 , the increase in local thickness not only improves the tensile strength of the connection point, but also helps to disperse and absorb local stress concentration caused by thermal expansion or mechanical load.

[0097] In some embodiments, the extension arm 4 helps to fix the thermal interface material 7, such as thermal conductive adhesive or gasket. The fixing effect of the inner extension arm can ensure that the thermal interface material 7 remains stable during packaging and use, avoiding displacement due to thermal expansion or mechanical vibration.

[0098] A method for packaging electronic devices, wherein a chip 6 is placed inside a heat dissipation cover 1 and a packaging substrate 5 for alignment and fixation, and then the chip 6 is electrically connected to the packaging substrate 5, wherein the chip 6 has a plurality of electrical connection points, and the packaging substrate 5 has pads corresponding to the electrical connection points, a bottom filling material is injected between the chip 6 and the packaging substrate 5, a thermal interface material 7 is coated on the inner surface of the heat dissipation cover 1 and above the chip 6, the bottom filling material is selected from a material that can enhance the stability and heat conduction efficiency of the chip 6 and the packaging structure, the packaging substrate 5 and the chip 6 are electrically connected by high-temperature reflow soldering using flip-chip technology, and a ball grid array package provides an electrical interconnection channel between the packaging substrate 5 and a PCB board.

[0099] The chip 6, the heat dissipation cover 1 and the packaging substrate 5 are packaged by bonding and fixing them together. The packaging material is selected from materials that can provide good protection and heat dissipation performance. The packaged electronic device is subjected to a thermal performance test to ensure that it meets the predetermined performance standards. The test includes but is not limited to a high temperature storage test and a temperature cycle test.

[0100] In addition, the chip 6 is a flip chip ball grid array chip, and the chip 6 is connected to the packaging substrate 5. This step can be completed in a variety of ways, including using flip chip technology to flip the chip 6 on the packaging substrate 5, installing the chip 6 on the packaging substrate 5 through high temperature reflow soldering, using conductive or non-conductive adhesives, welding, mechanical clamps or other fixing technologies. The fixing process not only ensures that the position of the chip 6 remains unchanged during the packaging process, but is also crucial to the reliability of the subsequent electrical interconnection and the overall packaging structure.

[0101] In addition, the adhesive or method for fixing the chip 6 needs to have good thermal and electrical conductivity, as well as long-term stability under thermal cycles and mechanical stress. The entire placement and alignment fixing process requires precise control to meet the requirements of high performance and high reliability of electronic devices.

[0102] First, the chip 6 is surface treated, and the bottom filling material is injected between the chip 6 and the packaging substrate 5. The appropriate packaging substrate material is selected, and the corresponding pads are designed and manufactured on the packaging substrate 5. These pads will correspond to the bottom of the chip. After the chip 6 and the packaging substrate 5 are positioned, the chip 6 and the packaging substrate 5 are aligned and fixed to enhance the stability of the chip 6 and the heat conduction efficiency in the packaging structure.

[0103] Then, the heat dissipation cover 1 is connected to the packaging substrate 5 by AD glue 8, and the packaging structure is cured to ensure that all adhesives and filling materials are fully hardened. The bottom filling process is used to fill the gap between the chip 6 and the packaging substrate 5. The assembled chip 6, heat dissipation cover 1 and packaging substrate 5 are subjected to processes such as ball planting, marking, appearance inspection and packaging. Then, the chip 6, heat dissipation cover 1 and packaging substrate 5 are packaged together to form a stable package body. The packaged electronic device is subjected to a thermal performance test to ensure that it meets the predetermined performance standards. The test includes but is not limited to a high-temperature storage test.

[0104] BM (Ball Mount) high temperature reflow soldering is a high temperature process used to complete the electrical connection between the package substrate 5 and the BGA solder ball. A layer of flux is applied to the ball pad of the package substrate 5 to facilitate ball placement and remove surface oxides. Then, Ball Placement is performed, and the solder ball is accurately placed on the ball pad of the substrate using a fixture. After ball placement, Reflow is performed to melt the solder ball and form a common metal with the solder ball pad to connect. Finally, the residual flux is cleaned with a solvent from the ball-placed product.

[0105] HTSL (High Temperature Storage Life) is a reliability test step used to evaluate the performance and stability of the package structure under long-term high temperature conditions. In this test, the packaged components are placed in a high temperature environment, usually at a temperature of 150°C, for 500 hours.

[0106] The purpose of high temperature storage test is to simulate the high temperature environment that the package structure may encounter during actual use, so as to detect its performance degradation under high temperature, such as degradation of thermal interface materials, warping and delamination of package structure, etc. Through HTSL test, the long-term reliability and durability of the package structure can be evaluated to ensure its stability in actual application.

[0107] After BM high-temperature reflow and HTSL high-temperature storage tests, the degradation of the four corners of the thermal interface material edge will be aggravated. However, after these high-temperature processes, the thermal interface material degradation of the heat sink with an angled extension arm design is significantly better than that of a conventional heat sink, showing better performance and stability. The angled extension arm design can effectively alleviate the impact of high temperature on the packaging structure and improve the heat dissipation performance and reliability of the product.

[0108] In some embodiments, a high temperature test is performed to compare the special-shaped heat dissipation cover and the conventional heat dissipation cover packaging structure with the angled heat dissipation cover packaging structure. Figure 5 and Figure 6 As shown in the figure, all of them have undergone BM (Ball Mount) and reliability test high temperature storage HTSL (High Temperature Storage Life) to detect the degree of degradation of the thermal interface material at the four corners of the chip. The storage condition of the high temperature test is 150°C and it needs to be tested for 500 hours.

[0109] Specifically, in the preparation stage of the BM process, the bottom of the substrate will be pre-printed with flux, which is a mixture with rosin as the main component and has a certain viscosity, so that the BGA solder ball is aligned with the substrate pad. After that, the entire assembly is placed in a reflow oven and heated to a certain temperature, which is usually higher than the melting point of the solder. At high temperature, the BGA solder ball melts and flows to the pad to form a spherical connection under the action of surface tension and wetting force. The assembly is then cooled and the solder re-solidifies to form a stable electrical and mechanical connection.

[0110] The high temperature heating during the BM (Ball Mount) process causes the thermal interface material to undergo thermal expansion and contraction, which may cause thermal stress. The BM is after the support block is mounted. The high temperature environment of the BM will cause the substrate and the chip to deform inconsistently, resulting in warping, thereby causing chip corner interface problems, such as Figure 5 (a) and Figure 6As shown in (a), the thermal interface degradation of the conventional heat sink and the special-shaped heat sink after ball mounting is compared. There is no obvious difference between the conventional heat sink and the special-shaped heat sink in the ball mount high-temperature reflow soldering thermal cycle test.

[0111] However, after high temperature storage of HTSL, Figure 5 As shown in (b), the thermal interface material at the four corners where the conventional heat dissipation cover and the chip meet has been significantly degraded, and the four corners of the chip on the conventional heat dissipation cover have basically become rounded, as shown in Figure 6 As shown in (b), although the four corners of the chip at the thermal interface of the special-shaped heat sink cover have degraded to a certain extent, the right-angle trend is obvious, and the effect is much better than that of the conventional heat sink cover. The special-shaped heat sink cover has better thermal stress resistance.

[0112] HTSL (High Temperature Storage Life) is a reliability test used to evaluate the long-term stability of electronic devices in high temperature environments. During the preparation stage, packaged electronic devices are placed in a specific test environment. The temperature of the test environment is set at a higher level, usually 150°C, to simulate the use of devices under extreme high temperature conditions. The devices are stored in a high temperature environment for a certain period of time. The test time mentioned in the document is 500 hours. After the test, the device is observed and analyzed to evaluate the impact of high temperature on its performance and structure.

[0113] like Figure 5 and Figure 6 As shown in the figure, the HTSL test is used to evaluate the effect of different heat sink cover designs on thermal interface material degradation. After long-term operation and multiple thermal cycles, the thermal interface material of the conventional heat sink cover degrades more obviously at the four corners, while the angled extension arm heat sink cover shows better performance and less degradation. This shows that the extension arm 4 design can effectively alleviate the adverse effects of high-temperature storage on the thermal interface material and improve the heat dissipation performance and reliability of the packaging structure. Due to its design advantages, the heat sink 1 may gradually show differences in thermal interface material degradation from the conventional heat sink cover.

[0114] In some embodiments, the special-shaped heat sink cover design effectively improves the structural stability of the heat sink cover by adding extension arms on the inner sides of the four corners of the heat sink cover to form extension arms. The angled extension arm packaging structure can avoid stress concentration at the edge of the thermal interface material, effectively alleviate the subsequent high-temperature reflow and degradation of the thermal interface material after reliability testing, optimize the product coverage, and improve the product's heat dissipation performance.

[0115] In addition, compared with the traditional heat sink cover, the heat sink cover design of the present application shows less thermal interface material degradation after high temperature storage test, maintains the performance of the thermal interface material, and thus optimizes the heat conduction efficiency. After the high temperature storage test (HTSL), the special-shaped heat sink cover shows a slower thermal interface material degradation rate and maintains long-term heat dissipation performance.

[0116] In some embodiments, the material selection of the heat dissipation cover 1 takes into account the matching of the thermal expansion coefficients of the chip and the packaging substrate, reducing the internal stress caused by thermal expansion mismatch. By optimizing the design of the heat dissipation cover and the extension arm, the reliability of the packaging structure of the present application in long-term operation is significantly improved.

[0117] It should be noted that the special-shaped heat dissipation cover 1 made of high thermal conductivity material, combined with the optimized geometric structure, significantly improves the heat conduction efficiency from the chip to the heat dissipation cover. The extension arms 4 extending from the inner sides of the four corners of the heat dissipation cover 1 effectively disperse the stress generated during assembly and operation, reduce warping, and improve the reliability of the packaging structure.

[0118] In addition, the material selection and surface treatment of the special-shaped heat dissipation cover 1 and the extension arm 4 take different environmental conditions into consideration, thereby ensuring the stability of the packaged device under various environmental conditions.

[0119] In this specification, the special-shaped heat dissipation cover brings a double improvement in heat dissipation performance and mechanical stability to the field of electronic device packaging, meets the strict requirements of high-performance electronic equipment on heat dissipation and reliability, and takes into account production costs and environmental adaptability.

[0120] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A special-shaped heat dissipation cover, characterized in that: Applied to chip heat dissipation and packaging, the heat dissipation cover comprises a heat dissipation cover plate and support blocks arranged around the bottom of the heat dissipation cover plate; Among them, the bottom center area of ​​the heat dissipation cover is used to contact the chip, and the heat dissipation cover is used for heat conduction and heat dissipation of the chip; the support block is arranged around the bottom center area of ​​the heat dissipation cover, and extends a preset area to the bottom center area of ​​the heat dissipation cover at the corners around it to form an extension arm, and the extension arm and the support block are used together to bond with the FCBGA packaging substrate, so that the extension arm is equivalent to adding four reinforcing ribs on the inner sides of the four corners of the heat dissipation cover, so as to increase the pulling force of the heat dissipation cover on the four corners of the FCBGA packaging substrate at the maximum stress point to disperse the contact stress between the heat dissipation cover and the chip.

2. The special-shaped heat dissipation cover according to claim 1, characterized in that: The distal end of the extension arm is in an arc shape; and / or the proximal end of the extension arm connected to the edge of the support block is in an arc shape.

3. The special-shaped heat dissipation cover according to claim 2, characterized in that: The distal end and the proximal end of the extension arm are both in the shape of semicircular arcs.

4. The special-shaped heat dissipation cover according to claim 1, characterized in that: The heat dissipation cover is a structural member made of a material with high thermal conductivity, and the material with high thermal conductivity includes any one of the following materials: copper, stainless steel, ceramic; And or, the support block, the extension arm and the heat dissipation cover plate are integrally formed.

5. An electronic device packaging structure, comprising a packaging substrate, a heat dissipation cover and a chip, characterized in that: The heat dissipation cover is a special-shaped heat dissipation cover as described in any one of claims 1 to 4; the chip is mounted on the upper surface of the packaging substrate; a thermal interface material is coated between the chip and the heat dissipation cover; the heat dissipation cover is bonded and fixed to the packaging substrate.

6. The electronic device packaging structure according to claim 5, characterized in that: The chip is a flip chip ball grid array chip, and the chip is flipped on the packaging substrate by flip chip technology, wherein the chip is mounted on the packaging substrate by high temperature reflow soldering; And / or, a ball grid array package solder joint is disposed at the bottom of the package substrate, and the ball grid array package solder joint is used for electrical interconnection between the package substrate and the PCB board.

7. The electronic device packaging structure according to claim 5, characterized in that: The heat dissipation cover and the packaging substrate are fixed by using AD glue; and / or, the gap between the chip and the packaging substrate is filled with a bottom filling process; And / or, the thermal interface material includes one or more of the following materials: epoxy resin-based thermal conductive adhesive with silver and / or copper as additives, and indium sheet.

8. A method for packaging an electronic device, characterized in that: include: electrically connecting the chip to the packaging substrate; Coating a thermal interface material on the inner surface of the heat dissipation cover and above the chip, wherein the heat dissipation cover is a special-shaped heat dissipation cover as claimed in any one of claims 1 to 4; The heat dissipation cover is bonded and fixed to the packaging substrate.

9. The electronic device packaging method according to claim 8, characterized in that: The chip is a flip chip ball grid array chip; electrically connecting the chip to the packaging substrate includes: using flip chip technology to flip the chip on the packaging substrate, wherein the chip is installed on the packaging substrate through high temperature reflow soldering.

10. The electronic device packaging method according to claim 8, characterized in that: The electronic device packaging method further comprises: using a bottom filling process to fill a gap between the chip and the packaging substrate.

Images