Chip packaging method, chip packaging structure and computer equipment
By using graphite sheets as thermal interface material in the chip packaging structure, the problems of low thermal performance and packaging efficiency of thermal interface materials in the prior art are solved, and more efficient thermal performance and more efficient packaging efficiency are achieved.
Patent Information
- Application Number
- CN202411569693.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-04
- Publication Date
- 2025-02-21
AI Technical Summary
In the existing chip packaging technology, the thermal interface material has low heat dissipation performance and packaging efficiency, especially during the use of high-power chips, resulting in unstable heat dissipation performance.
The graphite sheet is used as the thermal interface material between the chip and the heat dissipation cover. The graphite sheet is adhered to the thermal interface material setting area of the heat dissipation cover, and the graphite sheet is closely in contact with the surface of the chip and the heat dissipation cover by pressing to form a chip packaging structure. .
By using graphite sheets as thermal interface material, the cavity between the thermal interface material, the chip and the heat dissipation cover is avoided, the heat dissipation performance is improved, the packaging process is simplified, and the packaging efficiency is improved.
Smart Images
Figure CN119495573A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of chip packaging technology, and specifically to a chip packaging method, a chip packaging structure and a computer device. Background Art
[0002] As the power of the chip increases, the temperature of the chip during use is also getting higher and higher, which puts higher requirements on the heat dissipation performance and reliability of the chip packaging structure. In the chip packaging structure, TIM (Thermal Interface Material) is filled between the chip and the heat dissipation cover to transfer heat between the chip and the heat dissipation cover. Therefore, TIM is crucial to the heat dissipation performance and packaging effect of the chip packaging structure. In this context, how to provide a technical solution to improve the heat dissipation performance and packaging efficiency of the chip packaging structure has become a technical problem that technicians in this field need to solve urgently. Summary of the invention
[0003] To solve the above problems, the embodiments of the present application provide a chip packaging method, a chip packaging structure and a computer device.
[0004] In a first aspect, an embodiment of the present application provides a chip packaging method, comprising:
[0005] Providing a basic packaging structure, the basic packaging structure comprising a substrate and a flip chip connected to an upper surface of the substrate;
[0006] Adhere the graphite sheet to the thermal interface material setting area of the heat dissipation cover, wherein the thermal interface material setting area of the heat dissipation cover is used to set the thermal interface material; wherein the graphite sheet is made of a graphene sheet filled in a polymer material, and serves as the thermal interface material between the heat dissipation cover and the flip chip;
[0007] The heat dissipation cover is pressed together with the basic packaging structure, so that the graphite sheet adhered to the heat dissipation cover is pressed together with the heat dissipation cover and the surface of the flip chip to form a chip packaging structure.
[0008] In a second aspect, the embodiment of the present application further provides a chip packaging structure, including:
[0009] substrate;
[0010] a flip chip connected to the upper surface of the substrate;
[0011] A heat dissipation cover is pressed with the substrate, a graphite sheet is adhered to the thermal interface material setting area of the heat dissipation cover where the thermal interface material is set, and the graphite sheet is pressed with the surface of the flip chip; wherein the graphite sheet is made of a graphene sheet filled in a polymer material, and serves as the thermal interface material between the heat dissipation cover and the flip chip.
[0012] In a third aspect, an embodiment of the present application further provides a computer device, comprising the chip packaging structure as described in the second aspect.
[0013] The chip packaging method provided in the embodiment of the present application uses a graphite sheet as a thermal interface material to fill the space between the flip chip and the heat dissipation cover, adheres the graphite sheet to the thermal interface material setting area of the heat dissipation cover for setting the thermal interface material, and then presses the heat dissipation cover with the basic packaging structure to press the graphite sheet with the surface of the flip chip. The pressed graphite sheet is in close contact with the flip chip and the heat dissipation cover, which can avoid the generation of voids between the thermal interface material, the chip and the heat dissipation cover, thereby improving the heat dissipation performance; and by using the graphite sheet as the thermal interface material to fill the space between the chip and the heat dissipation cover, it can avoid the gradual deterioration of the heat dissipation effect of the indium metal material, or the voids generated during the welding process of the indium metal material affecting the heat dissipation performance of the chip and the complex welding process of the indium metal material, thereby improving the heat dissipation performance and packaging efficiency of the chip packaging. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0015] Figure 1 to Figure 4 It is a structural schematic diagram corresponding to each step in a chip packaging process.
[0016] Figure 5 It is a structural schematic diagram of a chip packaging method provided in an embodiment of the present application.
[0017] Figure 6 It is another structural schematic diagram of the chip packaging method provided in an embodiment of the present application.
[0018] Figure 7 It is a cross-sectional schematic diagram of another structure of the chip packaging method provided in an embodiment of the present application.
[0019] Figure 8a It is a schematic diagram of the first orientation surface of the graphite sheet in the chip packaging method provided in an embodiment of the present application.
[0020] Figure 8b It is a schematic diagram of the second orientation surface of the graphite sheet in the chip packaging method provided in an embodiment of the present application.
[0021] Fig. 9 This is another structural schematic diagram of the chip packaging method provided in an embodiment of the present application.
[0022] Fig.10 This is another structural schematic diagram of the chip packaging method provided in an embodiment of the present application.
[0023] Fig.11 It is a cross-sectional schematic diagram of another structure of the chip packaging method provided in an embodiment of the present application.
[0024] Fig.12a This is another schematic diagram of the first facing surface of the graphite sheet in the chip packaging method provided in an embodiment of the present application.
[0025] Figure 12b This is another schematic diagram of the second facing surface of the graphite sheet in the chip packaging method provided in an embodiment of the present application.
[0026] Fig.13 It is a schematic diagram of a chip packaging structure provided in an embodiment of the present application.
[0027] Fig.14 It is another schematic diagram of the chip packaging structure provided in an embodiment of the present application.
[0028] Fig.15 It is a schematic diagram of the structure of the graphite sheet provided in the embodiment of the present application. DETAILED DESCRIPTION
[0029] As described in the background technology section, there is room for improvement in the heat dissipation performance and packaging efficiency of existing chip packages.
[0030] In existing packaging technologies, organic materials or indium metal materials are usually used as thermal interface materials. However, as the package size becomes larger and larger, both organic materials and indium have their own problems.
[0031] The thermal conductivity of organic materials is relatively low, making it difficult to effectively cope with the high heat density of large-size chips. In addition, the mechanical properties of organic materials will gradually deteriorate under long-term high-temperature working conditions, which may cause the thermal interface material to fail or fall off, affecting the stability of the package's heat dissipation performance.
[0032] As a high thermal conductivity metal material, indium metal material has good thermal conductivity, but its thermal expansion coefficient does not match that of chips and packaging materials. In addition, if it is exposed to high temperature for a long time, indium metal material may degrade and affect the heat dissipation performance of the package.
[0033] It can be seen that the stability of the heat dissipation performance of the existing chip packaging needs to be improved. The following is an analysis of the reasons why the heat dissipation performance of the chip packaging needs to be improved in combination with a chip packaging process.
[0034] Figure 1-Figure 4 It is a schematic diagram of the various structures in the chip packaging process. Figure 1As shown, after the chip 200 is mounted on the substrate 100, the gap between the chip 200 and the substrate 100 is filled with bottom filling material 201. The substrate 100 is also provided with components 110. Specifically, the components 110 can be capacitors.
[0035] If indium metal material is used as thermal interface material to fill the space between the chip and the heat sink, in order to prevent the indium metal material from melting or boiling during the welding process, causing the indium metal material to contact components such as capacitors, such as Figure 2 As shown, a protective cover 111 for protecting the component 110 needs to be provided on the substrate 100. The protective cover protects the component 110 from contacting the indium metal material during the welding process.
[0036] Then, if Figure 3 As shown, after the soldering flux is sprayed on the chip 200, the indium metal material 202 is attached to the chip 200. Since the indium metal cannot directly form an IMC (Intermetallic compound) with the silicon on the chip, the indium metal cannot be welded on the chip, so the chip surface needs to be treated with backside metallization (BSM). In other words, the surface of the chip 200 that is attached to the indium metal material 202 has a layer of backside metal.
[0037] After the indium metal material 202 is attached to the chip 200, Figure 4 As shown, after the flux is sprayed on the indium metal material 202, the heat dissipation cover 210 is attached to the substrate 100, and the heat dissipation cover 210 is also attached to the indium metal material 202. Since the main material of the heat dissipation cover is nickel-plated copper, and the indium metal material and nickel cannot be directly welded, the heat dissipation cover 210 also needs to be gold-plated, that is, the surface where the heat dissipation cover 210 and the indium metal material 202 are attached needs to be plated with a layer of gold.
[0038] Afterwards, Figure 4 The package structure shown is subjected to high-temperature reflow soldering to make the chip 200, the indium metal material 202 and the heat dissipation cover 210 fit tightly together to form a final package structure.
[0039] The above chip packaging process uses indium metal material as TIM, which has the problems of low heat dissipation performance and low packaging efficiency of the chip packaging structure.
[0040] Specifically, indium metal material as TIM requires the introduction of BSM processing flow and gold plating processing flow in the chip packaging process. However, the BSM processing flow is complicated. The introduction of BSM processing flow and gold plating processing flow will extend the chip packaging operation cycle and affect the packaging efficiency.
[0041] The BSM process is also prone to abnormalities such as metal scratches or peeling, which can cause chip loss or large voids after welding, affecting heat dissipation performance. In addition, as the package size gradually increases, voids will be generated during the welding process of indium metal materials, affecting the heat dissipation effect. Furthermore, indium metal materials are prone to delamination during use as thermal interface materials, causing the heat dissipation effect of the chip to gradually deteriorate during operation, thereby affecting product performance and shortening product life.
[0042] It can be seen that the problems of low heat dissipation performance of the chip packaging structure and low packaging efficiency caused by unreasonable TIM selection need to be solved urgently.
[0043] Therefore, an embodiment of the present application provides a chip packaging method, including:
[0044] Providing a basic packaging structure, the basic packaging structure comprising a substrate and a flip chip connected to an upper surface of the substrate;
[0045] Adhere the graphite sheet to the thermal interface material setting area of the heat dissipation cover, wherein the thermal interface material setting area of the heat dissipation cover is used to set the thermal interface material; wherein the graphite sheet is made of a graphene sheet filled in a polymer material, and serves as the thermal interface material between the heat dissipation cover and the flip chip;
[0046] The heat dissipation cover is pressed together with the basic packaging structure, so that the graphite sheet adhered to the heat dissipation cover is pressed together with the heat dissipation cover and the surface of the flip chip to form a chip packaging structure.
[0047] The chip packaging method provided in the embodiment of the present application uses a graphite sheet as a thermal interface material to fill the space between the chip and the heat dissipation cover, adheres the graphite sheet to the thermal interface material setting area of the heat dissipation cover, and after the heat dissipation cover is pressed with the basic packaging structure, the graphite sheet adhered to the heat dissipation cover is pressed with the surfaces of the heat dissipation cover and the flip chip. The pressed graphite sheet is in close contact with the flip chip and the heat dissipation cover, which can avoid the generation of voids between the thermal interface material, the chip and the heat dissipation cover, thereby improving the heat dissipation performance; and by using the graphite sheet as the thermal interface material to fill the space between the chip and the heat dissipation cover, it can avoid the gradual deterioration of the heat dissipation effect of the indium metal material, or the voids generated during the welding process of the indium metal material affecting the heat dissipation performance of the chip and the complex welding process of the indium metal material, thereby improving the heat dissipation performance and packaging efficiency of the chip packaging.
[0048] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.
[0049] Figure 5 Schematic diagram of a chip packaging method provided by an embodiment of the present application. Figure 5 In the chip packaging method provided in the embodiment of the present application, a basic packaging structure is first provided, and the basic packaging structure includes a substrate 300 and a flip chip 400 connected to the upper surface of the substrate 300.
[0050] The basic packaging structure is a packaging structure formed by connecting the flip chip 400 to the substrate 300. Specifically, the flip chip 400 can be connected to the substrate 300 by welding; the flip chip 400 is electrically connected to the substrate 300, but the heat generated by the flip chip 400 in the working state needs to be dissipated through the heat dissipation cover. In some embodiments, the basic packaging structure also includes an underfill 401, which is used to reduce the stress of the solder joints and improve the reliability of the basic packaging structure.
[0051] After providing the basic package structure, refer to Figure 6 , the graphite sheet 402 is adhered to the thermal interface material setting area of the heat dissipation cover 410, and the thermal interface material setting area of the heat dissipation cover 410 is used to set the thermal interface material; wherein the graphite sheet 402 is made of a graphene sheet filled in a polymer material, and serves as the thermal interface material between the heat dissipation cover 410 and the flip chip 400, and the polymer material can be a combination of one or more materials such as polyethylene, epoxy resin, rubber, etc.
[0052] Since the graphite sheet 402 replaces indium as the thermal interface material between the heat dissipation cover 410 and the flip chip 400, there is no need to gold plate the heat dissipation cover, nor is there any need to perform back metallization on the surface of the flip chip. However, since the graphite sheet cannot be directly fixed on the heat dissipation cover, in order to prevent the graphite sheet from shifting or falling off during the subsequent pressing process, the graphite sheet 402 needs to be adhered to the thermal interface material setting area of the heat dissipation cover 410. The thermal interface material setting area of the heat dissipation cover 410 should at least cover the position of the inner side of the heat dissipation cover 410 corresponding to the flip chip 400, so that the heat generated by the flip chip 400 can be conducted to the heat dissipation cover 410 for heat dissipation.
[0053] In some embodiments, the graphite sheet 402 includes: a first facing surface facing the heat dissipation cover 410, and a second facing surface facing the flip chip 400; the first facing surface includes an adhesion area, and a first direct heat conduction area for direct heat conduction with the heat dissipation cover 410;
[0054] The step of adhering the graphite sheet 402 to the thermal interface material area of the heat dissipation cover 410 includes: coating a viscous thermally conductive material 403 on the adhesion area of the first facing surface of the graphite sheet 402; adhering the graphite sheet 402 to the thermal interface material setting area of the heat dissipation cover using the adhesion area coated with the viscous thermally conductive material, and the first direct heat conduction area is in contact with the thermal interface material setting area.
[0055] The first facing surface of the graphite sheet 402 facing the heat dissipation cover 410 includes an adhesion area and a first direct heat conduction area for direct heat conduction with the heat dissipation cover 410, wherein the adhesion area is coated with a viscous heat conductive material, and the graphite sheet 402 is adhered to the thermal interface material area of the heat dissipation cover 410 using the viscous heat conductive material 403, which can prevent the graphite sheet 402 from shifting or falling during the chip packaging process without sacrificing the heat dissipation performance. The viscous heat conductive material 403 includes but is not limited to thermal conductive silicone grease, thermal conductive silica gel, etc. The first direct heat conduction area is in contact with the thermal interface material setting area on the heat dissipation cover 410, so that the graphite sheet 402 and the heat dissipation cover 410 are directly heat-conducted, that is, the heat generated by the chip 400 can be directly conducted to the heat dissipation cover 410 through the first direct heat conduction area.
[0056] In some specific embodiments, the adhesion area is the edge area of the first facing surface, the first direct heat conduction area is the main area of the first facing surface, and the edge area of the first facing surface is located outside the main area of the first facing surface; the area of the main area of the first facing surface is larger than the area of the flip chip 400; coating the adhesive thermally conductive material 403 on the adhesion area of the first facing surface of the graphite sheet 402 includes: coating the adhesive thermally conductive material 403 on the adhesion area of the first facing surface of the graphite sheet 402 by a ring-shaped dispensing method; wherein the adhesion area is coated with the adhesive thermally conductive material 403 in a ring shape.
[0057] Figure 7 Yes Figure 6 The structure shown is a cross-sectional view of the A-A' plane, refer to Figure 7 , looking at the heat dissipation cover 410 from the A-A' plane, the adhesion area of the first facing surface of the graphite sheet 402 is formed by a ring-shaped dispensing method. Figure 7 As shown by the dotted line in , the adhesion area coated with the sticky thermal conductive material 403 is the edge area of the first facing surface. It can be seen that the outer edge of the first facing surface of the graphite sheet 402 facing the heat dissipation cover 410 is used to adhere to the heat dissipation cover 410. Figure 8a Schematic diagram of the first orientation of the graphite sheet in the chip packaging method provided in the embodiment of the present application, with reference to Figure 8a The outer edge of the first facing surface (i.e., the adhesion area) is coated with a viscous thermally conductive material 403, and the main area of the first facing surface (i.e., the first direct heat conduction area) is not coated with a viscous thermally conductive material. Since the thermal conductivity of the thermally conductive material is lower than that of the graphite sheet 402, the annular adhesion area coated with the thermally conductive material 403 surrounds the first direct heat conduction area, which can maximize the heat generated by the flip chip 400 and conduct it to the heat dissipation cover, thereby preventing the viscous thermally conductive material 403 from affecting the heat conduction and causing the thermal conductivity of the graphite sheet 402 to decrease.
[0058] The first direct heat conduction region is the main area of the first facing surface, the first direct heat conduction region is opposite to the flip chip 400 in contact with the second facing surface, and the area of the first direct heat conduction region is larger than the area of the flip chip 400; that is, the first direct heat conduction region opposite to the flip chip 400 does not have the thermal conductive material 403, so that the heat generated by the chip 400 can be directly conducted to the heat dissipation cover 410 through the first direct heat conduction region.
[0059] In some embodiments, the second facing surface includes: a second direct heat conduction region for direct heat conduction with the flip chip; the second direct heat conduction region of the second facing surface is opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is larger than that of the second direct heat conduction region.
[0060] Figure 8b Schematic diagram of the second orientation of the graphite sheet in the chip packaging method provided in the embodiment of the present application, with reference to Figure 8b , the area corresponding to the flip chip 400 is the second direct heat conduction area. After the heat dissipation cover is pressed together with the basic packaging structure, the graphite sheet adhered to the heat dissipation cover is pressed together with the surfaces of the heat dissipation cover and the flip chip, and the second direct heat conduction area is pressed together with the surface of the flip chip. Then, the heat generated by the flip chip 400 can be directly heat-conducted through the second direct heat conduction area, and then through the first direct heat conduction area, and finally conducted to the heat dissipation cover for heat dissipation.
[0061] Fig. 9 is another structural schematic diagram of the chip packaging method provided in the embodiment of the present application. Figure 7 and Fig. 9, the area of the first direct heat conduction region is larger than that of the second direct heat conduction region, and the size of the graphite sheet 402 is larger than that of the flip chip 400. For example, when the graphite sheet 402 and the flip chip 400 are both square, the width L2 of the graphite sheet 402 is larger than the width L1 of the flip chip 400. Specifically, the difference between the width L2 of the graphite sheet 402 and the width L1 of the flip chip 400 is 3 to 5 mm, for example, L2-L1=3 mm, 4 mm, 4.5 mm, 5 mm, etc. The area of the first direct heat conduction region is larger than that of the second direct heat conduction region, so that the width L2 of the graphite sheet 402 is larger than the width L1 of the flip chip 400, so that the efficiency of heat conduction will not be affected by the thermal conductive material 403, thereby improving the heat dissipation efficiency of the chip packaging structure.
[0062] In some embodiments, the number of the flip chips is at least two, the second facing surface has a plurality of second direct heat conduction regions for direct heat conduction with the flip chip, each of the plurality of second direct heat conduction regions is pressed against a corresponding flip chip; the plurality of second direct heat conduction regions are opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is greater than the area of the plurality of second direct heat conduction regions.
[0063] For example, Fig.10 Taking the structure shown as an example, when the number of the flip chips 400 is two, the second facing surface of the graphite sheet 402 has two second direct heat conduction areas for direct heat conduction with the two flip chips 400. The heat generated by one flip chip 400 is conducted to the heat dissipation cover 410 through a second direct heat conduction area on the second facing surface of the graphite sheet 402, so that one graphite sheet 402 can be used as a thermal interface material between the heat dissipation cover 410 and all the flip chips 400 to achieve heat dissipation for multiple flip chips 400.
[0064] Furthermore, the area of the first direct heat conduction region is greater than the areas of the plurality of second direct heat conduction regions, so that all the heat generated by the flip chips 400 can be efficiently conducted to the heat dissipation cover 410 through the graphite sheet 402, thereby achieving heat dissipation for the plurality of flip chips 400.
[0065] Fig.11 Yes Fig.10 The structure shown is a cross-sectional view of the A-A' plane, refer to Fig.11 , looking from the A-A' plane toward the heat dissipation cover 410, the adhesion area of the first facing surface of the graphite sheet 402 is formed by an annular dispensing method such as Fig.11As shown by the dotted line in , the adhesion area coated with the adhesive thermal conductive material 403 is the edge area of the first facing surface. Specifically, the area where the thermal conductive material 403 is applied by glue is an annular area, and the inner edge of the annular area surrounds the entire top surface area of the flip chip 400. It can be seen that the outer edge of the first facing surface of the graphite sheet 402 facing the heat dissipation cover 410 is used to adhere to the heat dissipation cover 410, and the adhesion area surrounds the entire top surface area of the flip chip 400.
[0066] Fig.12a is another schematic diagram of the first facing surface of the graphite sheet in the chip packaging method provided in an embodiment of the present application, with reference to Fig.12a The outer edge of the first facing surface (i.e., the adhesion area) is coated with a viscous thermally conductive material 403, and the main area of the first facing surface (i.e., the first direct heat conduction area) is not coated with a viscous thermally conductive material. Since the thermal conductivity of the thermally conductive material is lower than that of the graphite sheet 402, the annular adhesion area coated with the thermally conductive material 403 surrounds the first direct heat conduction area, which can maximize the heat generated by the flip chip 400 and conduct it to the heat dissipation cover, thereby preventing the viscous thermally conductive material 403 from affecting the heat conduction and causing the thermal conductivity of the graphite sheet 402 to decrease.
[0067] Figure 12b 2 is another schematic diagram of the second facing surface of the graphite sheet in the chip packaging method provided in an embodiment of the present application. Figure 12b , the area corresponding to one of the flip chips 400 is one of the second direct heat conduction areas. After the heat dissipation cover is pressed together with the basic packaging structure, the first facing surface is pressed together with the thermal interface material setting area of the heat dissipation cover, and each of the plurality of second direct heat conduction areas is pressed together with the surface of one of the flip chips corresponding thereto. Then, the heat generated by one of the flip chips 400 can be directly heat-conducted through one of the second direct heat conduction areas, and then through the first direct heat conduction area, and finally conducted to the heat dissipation cover for heat dissipation.
[0068] In some embodiments, when the number of the flip chips 400 is at least two, the number of the graphite sheets 402 disposed on the thermal interface material setting area is at least two, wherein at least two of the graphite sheets 402 have different thicknesses; each of the second facing surfaces has a second direct heat conduction area for direct heat conduction with the corresponding flip chip, and the first direct heat conduction area of each graphite sheet 402 is opposite to at least one second direct heat conduction area. When the number of the graphite sheets 402 is at least two, at least two graphite sheets 402 of different thicknesses are disposed, so that when the height difference of at least two flip chips 400 is large, heat can be dissipated for all of the flip chips 400 in the same chip packaging structure. Specifically, for example, when the number of the flip chips 400 is four, and the heights of the four flip chips 400 are 600um, 550um, 550um, and 450um respectively, the distances between the thermal interface material setting area of the heat dissipation cover and the upper surfaces of the four flip chips 400 are 150um, 200um, 200um, and 300um respectively, and four graphite sheets 402 are set on the thermal interface material setting area, and the thicknesses of the four graphite sheets 402 are 200um, 250um, 250um, and 350um respectively, so as to adapt to flip chips of different heights. After the heat dissipation cover is pressed together with the basic packaging structure, the heat generated by the four flip chips 400 can be directly heat conducted through the second direct heat conduction areas of the four graphite sheets 402, and then through the first direct heat conduction areas corresponding to the second direct heat conduction areas of the four graphite sheets 402, and finally conducted to the heat dissipation cover for heat dissipation.
[0069] After the graphite sheet 402 is adhered to the position of the inner side of the heat dissipation cover corresponding to the flip chip, Fig.13 , the heat dissipation cover 410 is pressed together with the basic packaging structure, and the graphite sheet 402 is pressed together with the surface of the flip chip 400 to form a chip packaging structure. Since the graphite sheet 402 is made of graphene sheets filled in a polymer material, wherein the polymer material has a certain elasticity, the heat dissipation cover 410 is pressed together with the basic packaging structure by pressing together, and the graphite sheet 402 adhered to the heat dissipation cover 410 is pressed together with the heat dissipation cover 410 and the surface of the flip chip, so that the graphite sheet 402 and the surface of the flip chip 400, and the graphite sheet 402 and the surface of the heat dissipation cover 410 can be closely attached under the action of pressure, avoiding the unevenness of the contact surface causing voids between the contact surfaces, and improving the heat dissipation performance of the chip packaging structure.
[0070] In some embodiments, the heat dissipation cover 410 is pressed together with the basic packaging structure so that the graphite sheet 402 adhered to the heat dissipation cover 410 is pressed together with the surfaces of the heat dissipation cover 410 and the flip chip 400 to form a chip packaging structure, including: pressing the heat dissipation cover together with the basic packaging structure so that the first facing surface is pressed together with the thermal interface material setting area of the heat dissipation cover, and the second direct heat conduction area is pressed together with the surface of the flip chip. It can be seen that the heat generated by the flip chip 400 is transferred to the graphite sheet 402 through the second direct heat conduction area on the graphite sheet 402. After the heat generated by the flip chip 400 is transferred to the graphite sheet 402, it is finally transferred to the heat dissipation cover 410 through the first direct heat conduction area and the thermal interface material setting area for heat dissipation.
[0071] In some embodiments, reference Fig.14 , the number of the flip chips is at least two, and the heat dissipation cover 410 is pressed together with the basic packaging structure so that the graphite sheet 402 adhered to the heat dissipation cover 410 is pressed together with the surfaces of the heat dissipation cover 410 and the flip chip 400 to form a chip packaging structure, including: pressing the heat dissipation cover and the basic packaging structure so that the first facing surface is pressed together with the thermal interface material setting area of the heat dissipation cover, and each of the multiple second direct heat conduction areas is pressed together with the surface of a corresponding flip chip. Furthermore, when the number of the graphite sheets 402 is at least two, wherein the thicknesses of at least two of the graphite sheets 402 are different, the heat dissipation cover 410 is pressed together with the basic packaging structure so that the graphite sheet 402 adhered to the heat dissipation cover 410 is pressed together with the surfaces of the heat dissipation cover 410 and the flip chip 400 to form a chip packaging structure, comprising: pressing the heat dissipation cover 410 together with the basic packaging structure so that the first facing surfaces of all the graphite sheets 402 are pressed together with the thermal interface material setting area of the heat dissipation cover 410, and each of the second direct heat conduction areas of all the graphite sheets 402 is pressed together with the surface of a corresponding flip chip 400. It can be seen that the heat generated by one of the flip chips 400 is conducted to the graphite sheet 402 through a second direct heat conduction area on the graphite sheet 402. After all the heat generated by the flip chip 400 is conducted to the graphite sheet 402, it is finally conducted to the heat dissipation cover 410 for heat dissipation through the first direct heat conduction area and the thermal interface material setting area.
[0072] In some specific implementations, during the process of pressing the heat dissipation cover 410 and the basic packaging structure, the displacement of the heat dissipation cover 410 is less than 0.1 mm, thereby ensuring the accuracy of the packaging process.
[0073] In some specific implementations, the pressure for pressing the heat dissipation cover 410 and the basic packaging structure is the number of flip chips multiplied by 9 kgf, which can make the chip packaging structure more solid while ensuring the heat dissipation performance of the chip packaging structure.
[0074] In some embodiments, the chip packaging method further includes: arranging components 310 on the substrate 300, and the components 310 are exposed in the heat dissipation cover 410 in the chip packaging structure. Since some components are large and cannot be packaged inside the flip chip, the components 310 are arranged on the substrate 300 as peripheral components of the flip chip 400. In the chip packaging method provided in the embodiment of the present application, since the graphite sheet 402 replaces indium as the thermal interface material between the heat dissipation cover 410 and the flip chip 400, the components 310 on the substrate 300 do not need to be protected. That is to say, in the embodiment of the present application, Fig.13 In the chip packaging structure shown, the component 310 is exposed in the heat dissipation cover 410 in the chip packaging structure, and there is no additional structure between the component 310 and the heat dissipation cover 410, thereby improving the internal space utilization of the packaging structure.
[0075] It should also be noted that in some embodiments, reference Fig.15 The graphene sheet 402 includes: at least one graphene sheet 4021 vertically distributed along the horizontal direction, and a polymer resin material 4022 filled on both sides of the graphene sheet.
[0076] Since the thermal conductivity of graphene has obvious anisotropic properties in different directions, for example, in the direction parallel to the graphene plane, the thermal conductivity of graphene can reach 1500W / (m·K), while in the direction perpendicular to the graphene plane, the thermal conductivity of graphene is only about 10W / (m·K). Therefore, in order to optimize the heat dissipation performance, the graphene sheet 4021 in the graphite sheet 402 is parallel to the direction of heat conduction, that is, the vertical direction of the graphite sheet 402, and corresponds to the height direction (BB' plane) of the flip chip 400. After the chip packaging structure is formed, the heat generated by the flip chip 400 is conducted to the heat dissipation cover 410 through the graphite sheet 402.
[0077] In some specific embodiments, the polymer resin material 4022 on both sides of the graphite sheet 402 is doped with auxiliary filling materials. The auxiliary filling materials are used to adjust the thermal conductivity and resilience of the graphite sheet 402 to adapt to different chip types. Specifically, the auxiliary filling materials are granular, and the auxiliary filling materials can be one or more of Ag, Cu, Al, AlN or Al2O3.
[0078] In some specific embodiments, the thermal conductivity of the graphite sheet in the vertical direction is greater than the thermal conductivity of indium. Using a graphite sheet with a thermal conductivity greater than the thermal conductivity of indium, 81 W / (m·K), can ensure the heat dissipation performance of the chip without using indium as the thermal interface material between the heat dissipation cover 410 and the flip chip 400. Specifically, in some embodiments, the thermal conductivity of the graphite sheet 402 is 90 W / (m·K).
[0079] In some specific embodiments, in order to match the thickness of different chips, the thickness of the graphite sheet is 200um to 400um, for example, 200um, 300um, 370um, 400um.
[0080] In some specific embodiments, the average density of the graphite sheet is 0.2 to 1.0 g / cm 3 , for example, 0.2 g / cm 3 , 0.4g / cm 3 , 0.75g / cm 3 , 1.0g / cm 3 Etc. The overall density of the graphite sheet can be adjusted by the ratio of the graphene sheet and the polymer resin material. In addition, since the greater the mass proportion of the graphene sheet in the graphite sheet, the better the heat dissipation performance, but relatively, the worse the elasticity of the graphite sheet, the graphite sheet may be broken or there may be voids on the bonding surface during the pressing process. Therefore, it is necessary to control the mass proportion of the graphene sheet in the graphite sheet. Specifically, the mass proportion of graphene in the graphite sheet is 5% to 30%, for example, 5%, 10%, 20%, 30%.
[0081] It can be seen that the chip packaging method provided by the present application uses a graphite sheet as a thermal interface material for filling the space between the chip and the heat dissipation cover, and adheres the graphite sheet to the thermal interface material setting area of the heat dissipation cover for setting the thermal interface material through a sticky thermal conductive material; further, a thermal conductive material is coated on the adhesion area of the first facing surface of the graphite sheet by a ring-shaped dispensing method, and there is no thermal conductive material on the first direct heat conduction area of the first facing surface, so as to avoid the thermal conductive material affecting the heat dissipation efficiency of the graphite sheet; after the heat dissipation cover is pressed with the basic packaging structure, the first facing surface is pressed with the thermal interface material setting area of the heat dissipation cover, and the second direct heat conduction area is pressed with the surface of the flip chip, and the pressed graphite sheet is in close contact with the flip chip and the heat dissipation cover, which can avoid the generation of voids between the thermal interface material, the chip and the heat dissipation cover, thereby improving the heat dissipation performance; and by using the graphite sheet as the thermal interface material for filling the space between the chip and the heat dissipation cover, it is avoided that the components inside the chip packaging structure are shielded by an additional structure, thereby improving the heat dissipation performance, packaging efficiency and internal space utilization of the chip packaging.
[0082] An embodiment of the present application also provides a chip packaging structure, comprising: a substrate; a flip chip connected to the upper surface of the substrate; a heat dissipation cover pressed with the substrate, wherein a graphite sheet is adhered to the thermal interface material setting area of the heat dissipation cover where the thermal interface material is set, and the graphite sheet is pressed with the surface of the flip chip; wherein the graphite sheet is made of a graphene sheet filled in a polymer material, and serves as a thermal interface material between the heat dissipation cover and the flip chip.
[0083] In some embodiments, the graphite sheet includes: a first facing surface facing the heat dissipation cover, and a second facing surface facing the flip chip; the first facing surface is pressed against the thermal interface material setting area of the heat dissipation cover, and the first facing surface includes: an adhesion area, an adhesion layer is provided between the adhesion area and the heat dissipation cover, and the adhesion layer is formed by a sticky thermal conductive material; and a first direct heat conduction area for direct heat conduction with the heat dissipation cover.
[0084] In some embodiments, the second facing surface includes: a second direct heat conduction region for direct heat conduction with the flip chip; the second direct heat conduction region of the second facing surface is opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is larger than that of the second direct heat conduction region.
[0085] In some embodiments, the adhesion area is the edge area of the first facing surface, the first direct heat conduction area is the main area of the first facing surface, and the edge area of the first facing surface is located outside the main area of the first facing surface; the area of the main area of the first facing surface is larger than the area of the flip chip.
[0086] In some embodiments, the number of the flip chips is at least two; the second facing surface has a plurality of second direct heat conduction regions for direct heat conduction with the flip chip, the plurality of second direct heat conduction regions are opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is greater than the area of the plurality of second direct heat conduction regions.
[0087] In some embodiments, the number of the flip chips is at least two; the number of the graphite sheets is at least two, wherein at least two of the graphite sheets have different thicknesses; each of the second-facing surfaces has a second direct heat conduction region for direct heat conduction with the corresponding flip chip, the second direct heat conduction region is opposite to the first direct heat conduction region of the first-facing surface, and the area of the first direct heat conduction region is greater than the area of the second direct heat conduction region.
[0088] In some embodiments, the graphite sheet includes: at least one graphene sheet distributed in a vertical direction, and a polymer resin material filled on both sides of the graphene sheet.
[0089] In some embodiments, the thermal conductivity of the graphene sheet in the vertical direction is greater than the thermal conductivity of indium.
[0090] In some embodiments, the graphene sheet has a thickness of 200 um to 400 um.
[0091] In some embodiments, the mass percentage of graphene in the graphite sheet is 5% to 30%.
[0092] In some implementations, the pressure of pressing the heat dissipation cover and the substrate is the number of the flip chips multiplied by 9 kgf.
[0093] In some embodiments, the chip packaging structure further includes: components disposed on the substrate, wherein the components are exposed in the heat dissipation cover.
[0094] An embodiment of the present application also provides a computer device, comprising the chip packaging structure as described in the above embodiment.
[0095] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application shall be subject to the scope defined by the claims.
Claims
1. A chip packaging method, characterized in that: include: Providing a basic packaging structure, the basic packaging structure comprising a substrate and a flip chip connected to an upper surface of the substrate; Adhere the graphite sheet to the thermal interface material setting area of the heat dissipation cover, wherein the thermal interface material setting area of the heat dissipation cover is used to set the thermal interface material; wherein the graphite sheet is made of a graphene sheet filled in a polymer material, and serves as the thermal interface material between the heat dissipation cover and the flip chip; The heat dissipation cover is pressed together with the basic packaging structure, so that the graphite sheet adhered to the heat dissipation cover is pressed together with the heat dissipation cover and the surface of the flip chip to form a chip packaging structure.
2. The chip packaging method according to claim 1, characterized in that: The graphite sheet comprises: a first facing surface facing the heat dissipation cover, and a second facing surface facing the flip chip; the first facing surface comprises an adhesion area, and a first direct heat conduction area for direct heat conduction with the heat dissipation cover; The thermal interface material area for adhering the graphite sheet to the heat dissipation cover comprises: Coating a viscous thermally conductive material on the adhesion area of the first facing surface of the graphite sheet; The graphite sheet is adhered to the thermal interface material setting area of the heat dissipation cover by using the adhesion area coated with adhesive thermal conductive material, and the first direct heat conduction area is in contact with the thermal interface material setting area.
3. The chip packaging method according to claim 2, characterized in that: The adhesion area is the edge area of the first facing surface, the first direct heat conduction area is the main area of the first facing surface, and the edge area of the first facing surface is located outside the main area of the first facing surface; the area of the main area of the first facing surface is larger than the area of the flip chip; The step of coating the adhesive thermally conductive material on the adhesion area of the first facing surface of the graphite sheet comprises: The adhesive region of the first facing surface of the graphite sheet is coated with a viscous thermally conductive material by means of a ring-shaped dispensing method; wherein the adhesive region is coated with the viscous thermally conductive material in a ring shape.
4. The chip packaging method according to any one of claims 2 to 3, characterized in that: The second facing surface comprises: a second direct heat conduction region for direct heat conduction with the flip chip; the second direct heat conduction region of the second facing surface is opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is larger than that of the second direct heat conduction region; The step of pressing the heat dissipation cover with the basic packaging structure so that the graphite sheet adhered to the heat dissipation cover is pressed with the heat dissipation cover and the surface of the flip chip to form a chip packaging structure comprises: The heat dissipation cover and the basic packaging structure are pressed together, so that the first facing surface is pressed together with the thermal interface material setting area of the heat dissipation cover, and the second direct heat conduction area is pressed together with the surface of the flip chip.
5. The chip packaging method according to any one of claims 2 to 3, characterized in that: The number of the flip chips is at least two; the second facing surface has a plurality of second direct heat conduction regions for direct heat conduction with the flip chips, the plurality of second direct heat conduction regions are opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is greater than the area of the plurality of second direct heat conduction regions; The step of pressing the heat dissipation cover with the basic packaging structure so that the graphite sheet adhered to the heat dissipation cover is pressed with the surfaces of the heat dissipation cover and the flip chip to form a chip packaging structure comprises: pressing the heat dissipation cover with the basic packaging structure so that the first facing surface is pressed with the thermal interface material setting area of the heat dissipation cover, and each of the plurality of second direct heat conduction areas is pressed with the surface of a corresponding flip chip.
6. The chip packaging method according to any one of claims 2 to 3, characterized in that: The number of the flip chips is at least two; the number of the graphite sheets is at least two, wherein at least two of the graphite sheets have different thicknesses; each of the second facing surfaces has a second direct heat conduction region for direct heat conduction with the corresponding flip chip, the second direct heat conduction region is opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is greater than the area of the second direct heat conduction region; The step of pressing the heat dissipation cover with the basic packaging structure so that the graphite sheet adhered to the heat dissipation cover is pressed with the surfaces of the heat dissipation cover and the flip chip to form a chip packaging structure includes: pressing the heat dissipation cover with the basic packaging structure so that the first facing surfaces of all the graphite sheets are pressed with the thermal interface material setting area of the heat dissipation cover, and each of the second direct heat conduction areas of all the graphite sheets is pressed with the surface of a corresponding flip chip.
7. The chip packaging method according to claim 1, characterized in that: The graphite sheet includes: at least one graphene sheet vertically distributed along a horizontal direction, and a polymer resin material filled on both sides of the graphene sheet.
8. The chip packaging method according to claim 7, characterized in that: The thermal conductivity of the graphite sheet in the vertical direction is greater than the thermal conductivity of indium.
9. The chip packaging method according to claim 7, characterized in that: The thickness of the graphite sheet is 200um-400um.
10. The chip packaging method according to claim 7, characterized in that: The average density of the graphite sheet is 0.2-1.0 g / cm 3 The mass proportion of graphene in the graphite sheet is 5% to 30%.
11. The chip packaging method according to claim 7, characterized in that: The polymer resin material filled on both sides of the graphene sheet is doped with auxiliary filling material.
12. The chip packaging method according to claim 1, characterized in that: The pressure for pressing the heat dissipation cover and the basic packaging structure together is the number of the flip chips multiplied by 9 kgf.
13. The chip packaging method according to claim 1, characterized in that: The method further comprises: Components are arranged on the substrate, and the components are exposed in the heat dissipation cover in the chip packaging structure.
14. A chip packaging structure, characterized in that: include: substrate; a flip chip connected to the upper surface of the substrate; A heat dissipation cover is pressed with the substrate, a graphite sheet is adhered to the thermal interface material setting area of the heat dissipation cover where the thermal interface material is set, and the graphite sheet is pressed with the surface of the flip chip; wherein the graphite sheet is made of a graphene sheet filled in a polymer material, and serves as the thermal interface material between the heat dissipation cover and the flip chip.
15. The chip packaging structure according to claim 14, characterized in that: The graphite sheet comprises: a first facing surface facing the heat dissipation cover, and a second facing surface facing the flip chip; the first facing surface is pressed against the thermal interface material setting area of the heat dissipation cover, and the first facing surface comprises: An adhesive region, wherein an adhesive layer is provided between the adhesive region and the heat dissipation cover, and the adhesive layer is formed of a viscous heat-conducting material; A first direct heat conduction region is directly heat-conducted with the heat dissipation cover.
16. The chip packaging structure according to claim 15, characterized in that: The adhesion area is the edge area of the first facing surface, the first direct heat conduction area is the main area of the first facing surface, the edge area of the first facing surface is located outside the main area of the first facing surface; the area of the main area of the first facing surface is larger than the area of the flip chip.
17. The chip packaging structure according to any one of claims 15 to 16, characterized in that: The second facing surface includes: a second direct heat conduction region for direct heat conduction with the flip chip; the second direct heat conduction region of the second facing surface is opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is larger than that of the second direct heat conduction region.
18. The chip packaging structure according to any one of claims 15 to 16, characterized in that: The number of the flip chips is at least two; the second facing surface has a plurality of second direct heat conduction regions for direct heat conduction with the flip chip, the plurality of second direct heat conduction regions are opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is greater than the area of the plurality of second direct heat conduction regions.
19. The chip packaging structure according to any one of claims 15 to 16, characterized in that: The number of the flip chips is at least two; the number of the graphite sheets is at least two, wherein at least two of the graphite sheets have different thicknesses; each of the second facing surfaces has a second direct heat conduction region for direct heat conduction with the corresponding flip chip, the second direct heat conduction region is opposite to the first direct heat conduction region of the first facing surface, and the area of the first direct heat conduction region is greater than the area of the second direct heat conduction region.
20. The chip packaging structure according to claim 14, characterized in that: The graphite sheet includes: at least one graphene sheet vertically distributed along a horizontal direction, and a polymer resin material filled on both sides of the graphene sheet.
21. The chip packaging structure according to claim 20, characterized in that: The thermal conductivity of the graphite sheet in the vertical direction is greater than the thermal conductivity of indium.
22. The chip packaging structure according to claim 20, characterized in that: The thickness of the graphite sheet is 200um-400um.
23. The chip packaging structure according to claim 20, characterized in that: The average density of the graphite sheet is 0.2-1.0 g / cm 3 The mass proportion of graphene in the graphite sheet is 5% to 30%.
24. The chip packaging structure according to claim 20, characterized in that: The polymer resin material filled on both sides of the graphene sheet is doped with auxiliary filling material.
25. The chip packaging structure according to claim 14, characterized in that: The pressure of pressing the heat dissipation cover and the substrate is the number of the flip chips multiplied by 9 kgf.
26. The chip packaging structure according to claim 14, characterized in that: The chip packaging structure further includes: components arranged on the substrate, and the components are exposed in the heat dissipation cover.
27. A computer device, characterized in that: It comprises the chip packaging structure as claimed in any one of claims 14 to 26.