Method for manufacturing chip heat dissipation structure

Abstract

This invention discloses a method for manufacturing a chip heat dissipation structure, belonging to the field of chip cooling devices. First, a low-viscosity thermally conductive resin is prepared and a thermally conductive wire is prepared. The thermally conductive resin is then immersed in the thermally conductive wire. The mixture is then formed through vacuum degassing and heat curing methods. The mixture is then cut into thin pads at a low temperature, the surface is insulated, and finally assembled to form a chip heat dissipation structure. The chip heat dissipation structure prepared by this method has the advantages of low thermal resistance, excellent insulation, and excellent heat dissipation.

Description

Technical Field

[0001] The invention belongs to the field of chip cooling devices and relates to a method for manufacturing a chip heat dissipation structure. Background Art

[0002] Modern electronic devices, such as AI graphics cards, power modules, and photovoltaic inverters, are becoming smaller, more integrated, and more versatile. This has led to an increase in the power density of these devices. The resulting heat buildup can lead to device failure and shortened service life. The main causes of electronic system failures include temperature, vibration, humidity, and dust, with temperature-related failures accounting for over 55%.

[0003] Traditional chip heat dissipation structures have high thermal resistance, slow heat transfer, and poor heat dissipation, making them difficult to meet the heat dissipation needs of developing artificial intelligence, high-power inverters, next-generation base stations, and high-power modules. The present invention provides a thermally conductive and insulating chip heat dissipation structure with the advantages of low thermal resistance, excellent insulation, and excellent heat dissipation. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for manufacturing a thermally conductive and insulating chip heat dissipation structure to solve the heat dissipation problem of chips with high heat generation, reduce the chip junction temperature and improve the chip reliability.

[0005] 1. A method for manufacturing a chip heat dissipation structure. The structure comprises a chip, a heat sink, a fastening structure, a circuit board, and a composite thermal pad. The manufacturing steps include:

[0006] S01, preparing thermal conductive resin: mixing thermal conductive fillers of a certain particle size and shape and adhesives in a certain proportion to obtain a flowable thermal conductive resin;

[0007] S02, preparing thermal conductive wires: cutting the thermal conductive film into thermal conductive wires of a certain width and length, spreading them in a container with an upper end open, and applying a certain pressure in the vertical direction to the thermal conductive wires through a mesh structure to compress them;

[0008] S03, preparing a mixture of thermally conductive wire and thermally conductive resin: pouring the thermally conductive resin obtained in step S01 into the container of S02, immersing the thermally conductive wire and the mesh structure, to obtain a mixture of thermally conductive wire and thermally conductive resin;

[0009] S04, vacuum defoaming: continuously pressing the mixture obtained in S03, and eliminating bubbles in the system by vacuum defoaming under conditions of a certain vacuum degree and a certain time;

[0010] S05, curing: curing the defoamed thermal conductive wire and thermal conductive resin mixture obtained in S04 at a certain temperature for a certain period of time to obtain a solid mixture;

[0011] S06, low temperature cutting: removing the mesh structure on the surface of the solid mixture obtained in S05, and cooling the mixture to a certain temperature to increase the hardness of the mixture, and then mechanically cutting the mixture to obtain a gasket of a certain thickness;

[0012] S07, surface insulation treatment: a sticky insulation layer is prepared on one or both sides of the gasket obtained in S06 by dipping or laminating, and then a release film is laminated on both sides to obtain a composite thermal pad with a certain insulation strength;

[0013] S08, assembly: The chip is mounted on the circuit board, with or without a heat sink mounted on the chip. According to the size of the chip or heat sink, the composite thermal pad is cut into a certain shape, the release film on one side of the insulating layer is peeled off, and the composite thermal pad is attached to the surface of the chip or heat sink. The release film on the other side is peeled off, and the heat sink is assembled and fastened to obtain the chip heat dissipation structure.

[0014] 2. Furthermore, it is characterized in that the thermally conductive filler in step S01 is one or more of alumina, aluminum nitride, silicon nitride, diamond, graphite, metal particles, silicon dioxide, boron nitride, carbon nanotubes, and graphene, and its particle size is 0.01-200 μm; the adhesive in step S01 is one or more of polyurethane, acrylic resin, and organic silicone, and its viscosity is 50-5000 mPa·s.

[0015] 3. Furthermore, it is characterized in that the thermally conductive film in step S02 is one or more of pyrolytic graphite film, expanded graphite film, carbon nanotube film, and reduced graphene oxide film; the surface of the thermally conductive film may or may not have an insulating coating, and the insulating coating is composed of one or more of polymer resins or ceramics; the thermal conductivity of the thermally conductive film is greater than 50 W / (m·K), and the cutting thickness is 5-300 μm, the cutting width is 100-5000 μm, and the cutting length is 0.1-1000 mm.

[0016] 4. Furthermore, it is characterized in that the pressure in the S02 step is less than 1 MPa, the material of the mesh structure is one or more of metal, polymer, and ceramic, and the mesh size is 10-2000 mesh.

[0017] 5. Furthermore, it is characterized in that the vacuum pressure in the S04 step is lower than -0.05MPa and the time is 0.5-24h.

[0018] 6. Furthermore, it is characterized in that the curing temperature of step S05 is 25-200°C and the curing time is 0.5-24.

[0019] 7. Furthermore, it is characterized in that the low temperature condition of the S06 step is minus 80°C or below, the mechanical cutting method is wire saw cutting or rotary blade cutting, and the cutting thickness is 0.03-10mm.

[0020] 8. Furthermore, it is characterized in that the insulating layer in step S07 is composed of an insulating thermally conductive filler and a resin, the insulating thermally conductive filler is one or more of alumina, diamond, glass fiber, silicon carbide, aluminum nitride, silicon nitride, and zinc oxide, and the resin is acrylic resin or silicone gel. The thickness of the insulating layer is 10-100 μm, and the volume resistivity is greater than 1.0×10 8 Ω·cm.

[0021] 9. Furthermore, it is characterized in that the chip package of the S08 is one or more of DIP, LGA, QFP, QFN, BGA, SOP, QFP, PGA, TO, and the heat flux density is 0.05-1000W / cm 2 , a side length of 0.5-100 mm, the heat sink material is one or more of metal, ceramic, and resin, and the thermal conductivity is greater than 10 W / (m·K).

[0022] 10. A method for manufacturing a chip heat dissipation structure, characterized in that the structure is prepared by any of the above methods and has the characteristics of insulation and high thermal conductivity, with a longitudinal thermal conductivity of 10-300 W / (m·K), a thickness of 50-8000 μm, and a volume resistivity greater than 1.0×10 8 Ω·cm.

[0023] Compared with the existing technology, this method has the following advantages:

[0024] (1) The thermally conductive and insulating chip heat dissipation structure provided by this method has the advantages of low thermal resistance, insulation, and good heat dissipation;

[0025] (2) The structure prepared by this method uses thermal conductive wires cut from high thermal conductivity films to construct a continuous thermal conduction path, resulting in high thermal conductivity and low thermal resistance;

[0026] (3) In the structure prepared by this method, the arrangement density of the thermal conductive wires is controlled by pressure, thereby controlling the mass percentage of the thermal conductive wires, achieving high thermal conductivity and low thermal resistance;

[0027] (4) The structure prepared by this method uses a resin immersion process, which can achieve batch preparation;

[0028] (5) The structure prepared by this method has a thermally conductive insulating layer, so it has good insulation and thermal conductivity;

[0029] (6) This method improves the cuttability of the mixture through a low-temperature cutting process to obtain a thin sheet structure, so the overall thermal resistance is smaller;

[0030] (7) The structure prepared by this method is suitable for heat dissipation of chips with various packaging structures, especially for heat dissipation of chips with large heat flux density. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attachment Figure 1 It is a process flow chart of the present invention.

[0032] Attachment Figure 2 It is a structural schematic diagram of the present invention.

[0033] Attachment Figure 3 This is a diagram of the chip junction temperature change. DETAILED DESCRIPTION

[0034] Specific embodiments of the present invention are described in detail below. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the present invention. In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other instances, well-known structures, circuits, materials, or methods are not specifically described to avoid obscuring the present invention.

[0035] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combinations and / or subcombinations in one or more embodiments or examples. The present invention is described in detail below with reference to the accompanying drawings.

[0036] In the following description of the technical solution of the present invention in conjunction with the accompanying drawings, the sizes, proportions and positional relationships of the elements are only exemplary, and the connection methods between the illustrated elements are only for illustration and are not intended to limit the present invention.

[0037] Example

[0038] The embodiment specifically describes a method for manufacturing a chip heat dissipation structure. A detailed description will be given below with reference to the accompanying drawings:

[0039] like Figure 2As shown, the chip heat dissipation structure mainly includes the following parts: thermal pad base 101, thermal wire 102, and insulation layer 103, which constitute the thermal pad assembly 104, substrate 105, chip 106, lower shell 107, and upper shell 108;

[0040] S01, preparing a low-viscosity thermally conductive resin: Mix a thermally conductive filler and an adhesive. The thermally conductive filler is spherical alumina powder with a D50 of 20 μm. The adhesive is silicone gel. The mass ratio of silicone gel to thermally conductive filler is 1:10. The preparation order is as follows: first, evenly mix silicone gel materials A and B, then add the spherical alumina powder, and stir evenly to obtain an uncured thermal pad substrate 101. The viscosity of the thermally conductive resin is 1400 mPa·s.

[0041] S02, preparing a thermal filament: cutting a thermal conductive film into 1 mm wide and 1 cm long thermal conductive filaments to obtain a thermal conductive filament 102. The thermal conductive film is a reduced graphene oxide film with a thickness of 100 μm and a 50 μm epoxy resin insulating coating on the surface. The thermal conductivity is 1200 W / (m·K). The thermal conductive filament is spread in a container with an open top. A certain pressure is applied vertically to the thermal conductive filament through a nylon mesh structure to compact the thermal conductive filament. The mesh size is 50 mesh and the pressure is 10 kPa.

[0042] S03, preparing a mixture of thermally conductive wire and thermally conductive resin: pouring the low-viscosity thermally conductive resin obtained in step S01 into the container of S02, immersing the thermally conductive wire and the mesh structure, to obtain a mixture of thermally conductive wire 102 and uncured thermally conductive pad substrate 101, wherein the mass percentage of the thermally conductive wire is 2.2%;

[0043] S04, vacuum degassing: continuously compress the mixture obtained in S03 and perform vacuum degassing at a pressure of -0.08 MPa for 10 h to eliminate bubbles in the system;

[0044] S05, curing: curing the defoamed thermal conductive wire and thermal conductive resin mixture obtained in S04 at 125° C. for 0.5 h to obtain a solid mixture;

[0045] S06, low-temperature cutting: removing the mesh structure on the surface of the solid mixture obtained in S05, and cooling the mixture to -120°C to increase the hardness of the mixture. The mixture is then cut by wire sawing using a cutting wire with diamond particles on the surface, a diameter of 0.3 mm, and a material of 1080 high-carbon steel to obtain a gasket with a thickness of 0.6 mm.

[0046] S07, Surface Insulation Treatment: A viscous insulation layer 103 is formed on both sides of the gasket obtained in S06 through a resin dipping process to obtain a thermal pad assembly 104. The insulation layer is composed of a mixture of alumina fiber felt and silicone gel, with a thickness of 50 μm. Release films are then applied to both sides to obtain a composite thermal pad with a certain insulation strength.

[0047] S08, assembly: The chip 106 is mounted on the substrate 105. The chip has a normal heat generation power of 30W. The package is BGA, not directly mounted on the heat sink. The size is 2cm×2cm, and the heat flux density is 7.5W / cm 2 The substrate is a PCB. Cut the composite thermal pad into chip size, peel off the release film on one side of the insulation layer, stick it to the surface of the chip 106, peel off the release film on the other side, assemble it to the lower shell 107 and fix it, and finally assemble the upper shell 108 and tighten it to obtain the chip heat dissipation structure. The lower shell 107 and the upper shell 108 are made of aluminum alloy, such as Figure 2 shown.

[0048] For the above structure, the chip is in normal working state, the chip heat generation power is 30W, and the heat mainly diffuses upward from the upper surface of the chip to the thermal pad assembly 104, first passing through the lower insulating layer 103, and then due to the presence of the thermal wire 102, the heat quickly diffuses to the upper insulating layer 103, and then the heat passes through the upper insulating layer 103 to the upper shell 108, and is transferred to the air through natural convection.

[0049] Comparative Example 1

[0050] The preparation process is basically the same as that of the embodiment, except that: Comparative Example 1 does not contain the heat conducting wire 102 and the insulating layer 103, and other process and material parameters are the same as those of the embodiment.

[0051] Comparative Example 2

[0052] The preparation process is basically the same as that of the embodiment, except that comparative example 2 does not contain the insulating layer 103, and other process and material parameters are the same as those of the embodiment.

[0053] Comparative Example 3

[0054] The preparation process is basically the same as that in Example 1, except that the cutting is performed at room temperature (20° C.), but no formed sheet structure can be obtained.

[0055] The above embodiment, comparative example 1, comparative example 2 and comparative example 3 were tested and detected, as shown in Table 1.

[0056] Table 1 Test and detection results of Example, Comparative Example 1, Comparative Example 2 and Comparative Example 3

[0057]

[0058] Note: Comparative Example 3 cannot obtain a formed sheet structure, and it is difficult to form the final heat dissipation structure.

[0059] Comparing the comparative example 1 with the embodiment, the comparative example 1 does not contain the heat conducting wire 102 and the insulating layer 103 during preparation. The longitudinal thermal conductivity of the thermal pad is reduced from 18.2W / (m·K) to 1.6W / (m·K), the junction temperature of the chip is increased from 78°C to 116°C, and the volume resistivity is increased from 5.6×10 11 Ω·cm increased to 4.5×10 13 Ω·cm, increasing thermal resistance from 0.086°C / W to 1.008°C / W. The introduction of thermal wire effectively improves the longitudinal thermal conductivity of the thermal pad, reducing thermal resistance and lowering chip junction temperature. Insulation layer 103 ensures insulation performance.

[0060] Comparing Comparative Example 2 with the embodiment, Comparative Example 2 does not contain the insulating layer 103 during preparation. The longitudinal thermal conductivity of the thermal pad is increased from 18.2W / (m·K) to 31.4W / (m·K), the junction temperature of the chip is reduced from 78°C to 74°C, and the volume resistivity is increased from 5.6×10 11 Ω·cm is reduced to 2.3Ω·cm, and thermal resistance is reduced from 0.086℃ / W to 0.05℃ / W. Although the introduction of the insulating layer reduces longitudinal thermal conductivity and increases thermal resistance, thereby increasing the chip junction temperature, it can effectively reduce the volume resistivity of the thermal pad to meet the requirements of insulation assembly.

[0061] Compare the junction temperatures of the three groups of chips, such as Figure 3 As shown, it can be observed that: compared with Comparative Example 1, the chip junction temperature of the embodiment and Comparative Example 2 is significantly reduced; compared with Comparative Example 2, the embodiment has good insulation and better overall performance.

[0062] In summary, the thermally conductive and insulating chip heat dissipation structure provided by this method has the advantages of low thermal resistance, good insulation and heat dissipation.

[0063] While the present invention has been described with reference to exemplary embodiments, it should be understood that the terms used are descriptive and illustrative rather than restrictive. Since the present invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above-described embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope of the appended claims. All changes and modifications that fall within the scope of the claims or their equivalents are intended to be covered by the appended claims.

Claims

1. A method for manufacturing a chip heat dissipation structure, characterized in that: The manufacturing steps include: S01, preparing thermal conductive resin: mixing thermal conductive filler with a particle size of 0.01-200 μm with an adhesive to obtain a flowable thermal conductive resin; S02, preparing thermal conductive wires: cutting the thermal conductive film into thermal conductive wires with a width of 100-5000 μm and a length of 0.1-1000 mm, spreading the thermal conductive wires in a container with an upper end open, and applying a pressure of less than 1 MPa in the vertical direction to the thermal conductive wires through a mesh structure to compact them; S03, preparing a mixture of thermally conductive wire and thermally conductive resin: pouring the thermally conductive resin obtained in step S01 into the container of S02, immersing the thermally conductive wire and the mesh structure, to obtain a mixture of thermally conductive wire and thermally conductive resin; S04, vacuum degassing: continuously compressing the mixture obtained in S03, and removing bubbles from the system by vacuum degassing under a vacuum pressure lower than -0.05 MPa for 0.5-24 h; S05, curing: curing the defoamed thermal conductive wire and thermal conductive resin mixture obtained in S04 at a temperature of 25-200° C. for a curing time of 0.5-24 hours to obtain a solid mixture; S06, low temperature cutting: removing the mesh structure on the surface of the solid mixture obtained in S05, and cooling the mixture to -80°C or below, thereby increasing the hardness of the mixture, and then mechanically cutting the mixture to obtain a gasket with a thickness of 0.03-10 mm; S07, surface insulation treatment: Prepare a sticky insulation layer on one or both sides of the gasket obtained in S06 by dipping or laminating, and then laminate release film on both sides to obtain a volume resistivity greater than 1.0×10 8 Ω·cm composite thermal pad; S08, assembly: The chip is mounted on the circuit board, with or without a heat sink mounted on the chip. According to the size of the chip or heat sink, the composite thermal pad is cut into corresponding shapes, the release film on one side of the insulating layer is peeled off, and the composite thermal pad is attached to the surface of the chip or heat sink. The release film on the other side is peeled off, and the heat sink is assembled and fastened to obtain the chip heat dissipation structure.

2. The preparation method according to claim 1, characterized in that The thermal conductive filler in step S01 is one or more of aluminum oxide, aluminum nitride, silicon nitride, diamond, graphite, metal particles, silicon dioxide, boron nitride, carbon nanotubes, and graphene; the adhesive in step S01 is one or more of polyurethane, acrylic resin, and organic silicone, with a viscosity of 50-5000 mPa·s.

3. The preparation method according to claim 1, characterized in that The thermally conductive film in step S02 is one or more of pyrolytic graphite film, expanded graphite film, carbon nanotube film, and reduced graphene oxide film. The surface of the thermally conductive film may or may not contain an insulating coating. The insulating coating is composed of one or more polymer resins or ceramics. The thermal conductivity of the thermally conductive film is greater than 50 W / (m·K) and the cutting thickness is 5-300 μm.

4. The manufacturing method according to claim 1, characterized in that In the step S02, the material of the mesh structure is one or more of metal, polymer, and ceramic, and the mesh size is 10-2000 mesh.

5. The manufacturing method according to claim 1, characterized in that The mechanical cutting method in step S06 is wire saw cutting or rotary blade cutting.

6. The manufacturing method according to claim 1, characterized in that The insulating layer in step S07 is composed of insulating thermal conductive filler and resin, the insulating thermal conductive filler is one or more of aluminum oxide, diamond, glass fiber, silicon carbide, aluminum nitride, silicon nitride, and zinc oxide, the resin is acrylic resin or silicone gel, and the thickness of the insulating layer is 10-100 μm.

7. The manufacturing method according to claim 1, characterized in that The chip package of S08 is one or more of DIP, LGA, QFP, QFN, BGA, SOP, QFP, PGA, TO, and the heat flux density is 0.05-1000W / cm 2 , a side length of 0.5-100 mm, the heat sink material is one or more of metal, ceramic, and resin, and the thermal conductivity is greater than 10 W / (m·K).

8. A chip heat dissipation structure, characterized in that: The structure is prepared by the method of any one of claims 1 to 7, and has the characteristics of insulation and high thermal conductivity, with a longitudinal thermal conductivity of 10-300 W / (m·K), a thickness of 50-8000 μm, and a volume resistivity greater than 1.0×10 8 Ω·cm.

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