Manufacturing method of chip heat dissipation structure

Abstract

The invention discloses a manufacturing method of a chip heat dissipation structure, and belongs to the field of chip cooling devices. The method comprises the following steps: firstly, preparing low-viscosity heat-conducting resin and preparing a heat-conducting wire, immersing the heat-conducting wire in the heat-conducting resin, then forming a mixture through methods such as vacuum defoaming and heating curing, then cutting the mixture into a thin pad at a low temperature, carrying out surface insulation treatment, and finally assembling to form the chip heat dissipation structure. The chip heat dissipation structure prepared by the method has the advantages of small thermal resistance, insulation and good 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, photovoltaic inverters, etc., have been developing towards smaller size, higher integration, and more functions, which has led to an increase in the power density of electronic devices. The heat accumulation caused by the increase in power density will lead to device failure and shortened service life. The main causes of electronic system failures include temperature, vibration, humidity, and dust, of which failures caused by temperature account for more than 55%.

[0003] The traditional chip heat dissipation structure has large thermal resistance, slow heat transfer and poor heat dissipation, which makes it difficult to meet the heat dissipation problems of developing artificial intelligence, high-power inverters, new 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, insulation and good 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 main components include a chip, a heat sink, a fastening structure, a circuit board, and a composite thermal pad; the manufacturing steps include: S01, preparing thermal conductive resin: mixing thermal conductive fillers with certain particle sizes and shapes and adhesives in a certain proportion to obtain flowable thermal conductive resin; S02, preparing a thermal conductive wire: cutting the thermal conductive film into thermal conductive wires of a certain width and length, spreading the thermal conductive wires in a container with an upper opening, and applying a certain pressure to the thermal conductive wires in a vertical direction through a mesh structure to compact the thermal conductive wires; S03, preparing a mixture of thermally conductive wires and thermally conductive resin: pouring the thermally conductive resin obtained in step S01 into the container of S02 to immerse the thermally conductive wires and the mesh structure, thereby obtaining a mixture of thermally conductive wires and thermally conductive resin; S04, vacuum defoaming: continuously compressing the mixture obtained in S03, and removing bubbles in the system by vacuum defoaming under the conditions of a certain vacuum degree and a certain time; 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; 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, the hardness of the mixture is increased, and then mechanical cutting is performed to obtain a gasket of a certain thickness; S07, surface insulation treatment: preparing a sticky insulation layer on one side or both sides of the gasket obtained in S06 by dipping or laminating process, and then laminating release films on both sides to obtain a composite thermal conductive pad with a certain insulation strength; S08, assembly: installing the chip on the circuit board, with or without a heat sink mounted on the chip, and cutting the composite thermal pad into a certain shape according to the size of the chip or the heat sink, peeling off the release film on one side of the insulating layer, attaching it to the surface of the chip or the heat sink, peeling off the release film on the other side, and then assembling the heat sink and fastening it to obtain a chip heat dissipation structure.

[0006] 2. Further, it is characterized in that the thermal 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 0.01-200μm; the adhesive in step S01 is one or more of polyurethane, acrylic resin, and organic silica gel, and its viscosity is 50-5000mPa·s.

[0007] 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, reduced graphene oxide film, the surface of the thermally conductive film contains or does 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 50W / (m·K), the cutting thickness is 5-300μm, the cutting width is 100-5000μm, and the cutting length is 0.1-1000mm.

[0008] 4. Furthermore, it is characterized in that the pressure in the S02 step is less than 1MPa, the material of the mesh structure is one or more of metal, polymer, and ceramic, and the mesh size is 10-2000 mesh.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 8. Furthermore, it is characterized in that the insulating layer of step S07 is composed of insulating thermal conductive filler and resin, the insulating thermal conductive filler is one or more of alumina, diamond, glass fiber, silicon carbide, aluminum nitride, silicon nitride, zinc oxide, 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.

[0013] 9. Furthermore, it is characterized in that the chip packaging form 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 , the side length is 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).

[0014] 10. A method for manufacturing a chip heat dissipation structure, characterized in that the structure is prepared by any of the above methods, has the characteristics of insulation and high thermal conductivity, has a longitudinal thermal conductivity of 10-300 W / (m·K), a thickness of 50-8000μm, and a volume resistivity greater than 1.0×10 8 Ω·cm.

[0015] Compared with the existing technology, this method has the following advantages: (1) The thermally conductive and insulating chip heat dissipation structure provided by the method has the advantages of low thermal resistance, insulation and good heat dissipation; (2) The structure prepared by this method uses a thermal conductive wire cut from a high thermal conductive film to construct a continuous thermal conductive path, so the thermal conductivity is high and the thermal resistance is small; (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, thereby achieving high thermal conductivity and low thermal resistance; (4) The structure prepared by this method uses a resin immersion process, which can achieve batch preparation; (5) The structure prepared by this method has a thermally conductive insulating layer, so it has good insulation and thermal conductivity; (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; (7) The structure prepared by this method is suitable for heat dissipation of chips with various packaging structures, especially the heat dissipation of chips with large heat flux density. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attached Figure 1 It is a process flow chart of the present invention.

[0017] Attached Figure 2It is a structural schematic diagram of the present invention.

[0018] Attached Figure 3 This is the chip junction temperature change diagram. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not have to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known structures, circuits, materials or methods are not specifically described.

[0020] Throughout the specification, references to "one embodiment", "an embodiment", "an example" or "an example" mean that a particular feature, structure or characteristic described in conjunction 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 do not necessarily all refer to the same embodiment or example. In addition, particular features, structures or characteristics may be combined in one or more embodiments or examples in any appropriate combination and / or subcombination. The present invention is described in detail below with reference to the accompanying drawings.

[0021] In the following description of the technical solution of the present invention in conjunction with the accompanying drawings, the size, proportion and position relationship of each element in the attachment are only exemplary, and the connection method between the illustrated elements is only for illustration and is not intended to limit the present invention.

[0022] Example The embodiment specifically describes a method for manufacturing a chip heat dissipation structure. The following will be described in detail with reference to the accompanying drawings: like Figure 2 As shown, the chip heat dissipation structure mainly includes the following parts: a thermal pad base 101, a thermal wire 102, and an insulating layer 103, which constitute a thermal pad assembly 104, a substrate 105, a chip 106, a lower shell 107, and an upper shell 108; S01, preparing low-viscosity thermally conductive resin: mixing thermally conductive filler and adhesive, wherein the thermally conductive filler is spherical alumina powder with a D50 of 20 μm, and the adhesive is silicone gel, and the mass ratio of silicone gel to thermally conductive filler is 1:10. The preparation sequence is: firstly uniformly mix silicone gel A and B materials, then add spherical alumina powder, and uniformly stir to obtain an uncured thermally conductive pad substrate 101, and the viscosity of the thermally conductive resin is 1400 mPa·s; S02, preparing a thermal conductive wire: cutting a thermal conductive film into thermal conductive wires of 1 mm width and 1 cm length to obtain a thermal conductive wire 102, wherein 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, and a thermal conductivity of 1200 W / (m·K), and is spread in a container with an upper opening, and a certain pressure is applied to the thermal conductive wire in a vertical direction through a nylon mesh structure to compress it, the mesh size is 50 mesh, and the pressure is 10 KPa; 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 to immerse the thermally conductive wire and the mesh structure, thereby obtaining a mixture of the thermally conductive wire 102 and the uncured thermally conductive pad substrate 101, wherein the mass percentage of the thermally conductive wire is 2.2%; S04, vacuum degassing: continue to press the mixture obtained in S03, and vacuum degassing at a pressure of -0.08 MPa for 10 h to eliminate bubbles in the system; 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; S06, low temperature cutting: remove the mesh structure on the surface of the solid mixture obtained in S05, and cool the mixture to -120°C, the hardness of the mixture is increased, and then the mixture is cut by wire saw, the cutting wire used is a 0.3mm diameter 1080 high carbon steel with diamond particles on the surface, to obtain a 0.6mm thick gasket; S07, surface insulation treatment: through the resin dipping process, a sticky insulation layer 103 is prepared on the front and back sides of the gasket obtained in S06 to obtain a thermal pad assembly 104, the insulation layer composition is a mixture of aluminum oxide fiber felt and silicone gel, the thickness is 50 μm, and then release films are attached to both sides to obtain a composite thermal pad with a certain insulation strength; S08, assembly: The chip 106 is mounted on the substrate 105. The chip has a normal working heat generation power of 30W. The package form 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 PCB. The composite thermal pad is cut into chip size, the release film on one side of the insulating layer is peeled off, and it is attached to the surface of the chip 106, and then the release film on the other side is peeled off, and then assembled to the lower shell 107 and fixed, and finally the upper shell 108 is assembled and fastened to obtain a chip heat dissipation structure. The lower shell 107 and the upper shell 108 are made of aluminum alloy, such as Figure 2 shown.

[0023] 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 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 the heat is transferred to the air through natural convection of the air.

[0024] Comparative Example 1 The preparation process is basically the same as that of the embodiment, except that: Comparative Example 1 does not contain the heat conductive wire 102 and the insulating layer 103, and other process and material parameters are the same as those of the embodiment.

[0025] Comparative Example 2 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.

[0026] Comparative Example 3 The preparation process is basically the same as that in the example, except that the cutting is performed at room temperature 20° C., but no formed sheet structure can be obtained.

[0027] The above embodiment, comparative example 1, comparative example 2 and comparative example 3 were tested and detected, as shown in Table 1.

[0028] Table 1 Test and detection results of Example, Comparative Example 1, Comparative Example 2 and Comparative Example 3

[0029] Note: Comparative Example 3 cannot obtain a formed sheet structure and is difficult to form the final heat dissipation structure.

[0030] Comparing the comparative example 1 with the embodiment, the comparative example 1 does not contain the heat conductive wire 102 and the insulating layer 103 during preparation, the longitudinal thermal conductivity of the thermal pad is reduced from 18.2 W / (m·K) to 1.6 W / (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 increases to 4.5×10 13 Ω·cm, the thermal resistance increases from 0.086℃ / W to 1.008℃ / W. The introduction of thermal wire can effectively improve the longitudinal thermal conductivity of the thermal pad, reduce thermal resistance and reduce the chip junction temperature. Insulation layer 103 ensures insulation capability.

[0031] 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 18.2 W / (m·K) to 31.4 W / (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 11Ω·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 insulation layer reduces the longitudinal thermal conductivity and increases the thermal resistance, thereby increasing the chip junction temperature, it can effectively reduce the volume resistivity of the thermal pad to meet the needs of insulation assembly.

[0032] 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 comprehensive performance.

[0033] In summary, the thermally conductive and insulating chip heat dissipation structure provided by the method has the advantages of low thermal resistance, good insulation and heat dissipation.

[0034] Although the present invention has been described with reference to typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should 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 fillers with certain particle sizes and shapes and adhesives in a certain proportion to obtain flowable thermal conductive resin; S02, preparing a thermal conductive wire: cutting the thermal conductive film into thermal conductive wires of a certain width and length, spreading the thermal conductive wires in a container with an upper opening, and applying a certain pressure to the thermal conductive wires in a vertical direction through a mesh structure to compact the thermal conductive wires; S03, preparing a mixture of thermally conductive wires and thermally conductive resin: pouring the thermally conductive resin obtained in step S01 into the container of S02 to immerse the thermally conductive wires and the mesh structure, thereby obtaining a mixture of thermally conductive wires and thermally conductive resin; S04, vacuum defoaming: continuously compressing the mixture obtained in S03, and removing bubbles in the system by vacuum defoaming under the conditions of a certain vacuum degree and a certain time; 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; 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, the hardness of the mixture is increased, and then mechanical cutting is performed to obtain a gasket of a certain thickness; S07, surface insulation treatment: preparing a sticky insulation layer on one side or both sides of the gasket obtained in S06 by dipping or laminating process, and then laminating release films on both sides to obtain a composite thermal conductive pad with a certain insulation strength; S08, assembly: installing the chip on the circuit board, with or without a heat sink mounted on the chip, and cutting the composite thermal pad into a certain shape according to the size of the chip or the heat sink, peeling off the release film on one side of the insulating layer, attaching it to the surface of the chip or the heat sink, peeling off the release film on the other side, and then assembling the heat sink and fastening it to obtain a chip heat dissipation structure.

2. The manufacturing 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, and its particle size is 0.01-200 μm; the adhesive in step S01 is one or more of polyurethane, acrylic resin, and organic silica gel, and its viscosity is 50-5000 mPa·s.

3. The manufacturing method according to claim 1, characterized in that: The thermally conductive film in step S02 is one or more of a pyrolytic graphite film, an expanded graphite film, a carbon nanotube film, and a reduced graphene oxide film. The surface of the thermally conductive film contains or does not contain an insulating coating, and the components of the insulating coating are one or more of a polymer resin or a ceramic. The thermal conductivity of the thermally conductive film is greater than 50W / (m·K), the cutting thickness is 5-300μm, the cutting width is 100-5000μm, and the cutting length is 0.1-1000mm.

4. The manufacturing method according to claim 1, characterized in that: In the step S02, the pressure 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.

5. The manufacturing method according to claim 1, characterized in that: In the step S04, the vacuum pressure is lower than -0.05 MPa and the time is 0.5-24 h.

6. The manufacturing method according to claim 1, characterized in that: The curing temperature of step S05 is 25-200° C., and the curing time is 0.5-24 hours.

7. The manufacturing method according to claim 1, characterized in that: The low temperature condition of the step S06 is minus 80° C. or below, and the mechanical cutting method is wire saw cutting or rotary blade cutting, with a cutting thickness of 0.03-10 mm.

8. The manufacturing method according to claim 1, characterized in that: The insulating layer of step S07 is composed of insulating thermal conductive filler and resin, wherein the insulating thermal 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.

9. The manufacturing method according to claim 1, characterized in that: The chip packaging form 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 , the side length is 0.5-100 mm, the heat sink material is one or more of metal, ceramic, resin, and the thermal conductivity is greater than 10 W / (m·K).

10. A method for manufacturing a chip heat dissipation structure, characterized in that: The structure is prepared by the method according to any one of claims 1 to 9, 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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