Aluminum-based silicon carbide substrate type integrated detector heat conduction assembly

Abstract

The invention provides an aluminum-based silicon carbide base material type integrated detector heat conduction assembly. The assembly comprises a graphite film heat conduction cable and a cold end head; the graphite film heat conduction cable comprises multiple layers of stacked graphite films, and the two ends of the graphite film heat conduction cable are a hot end and a cold end respectively. The hot end of the graphite film heat conduction cable is directly connected with the aluminum-based silicon carbide base material detector flange through brazing; the cold end of the graphite film heat conduction cable is fixed in the cold end head, and the cold end head is fixedly connected with a cold source to implement heat dissipation. The graphite film is used for replacing a copper cable to manufacture the heat conduction cable, so that the heat conduction capability is improved; a copper end of a traditional heat-conducting cable is removed, the heat-conducting cable and the aluminum-based silicon carbide flange are integrally formed through the high-temperature brazing and crimping forming technology, and the weight of a structural assembly is reduced while the contact thermal resistance of a heat dissipation link is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of image detector heat dissipation components, and in particular relates to an aluminum-based silicon carbide substrate-type integrated detector heat conduction component, which is used for heat dissipation control of precision image detectors with excessive power consumption, temperature sensitivity, and high temperature control accuracy. Background Art

[0002] In the field of image detection, with the continuous development of electronic imaging technology, image detectors tend to consume more and more power and are more and more sensitive to temperature, which places higher demands on detector temperature control. Therefore, efficient heat dissipation and precise temperature control of image detectors will become one of the key technologies in image detection research. At present, designs with extremely high requirements for temperature control require that the image detector be mounted on a flange to expand heat, and then use thermal cables to effectively transfer heat to the heat dissipation surface. However, traditional copper thermal cables are fixed to the aluminum-based silicon carbide detector flange with screws, resulting in an interface, resulting in a large contact thermal resistance, making heat diffusion difficult to meet the temperature control requirements of the detector. At the same time, the copper thermal cable has a high density and poor flexibility, which limits the promotion and application of the component and its operability.

[0003] Chinese Patent Publication No. CN201611201840X, "A Graphene-Reinforced Aluminum-Based Silicon Carbide Composite Material, Its Preparation Method, and Its Application," proposes a method for preparing graphene-reinforced aluminum-based silicon carbide composite materials using different components and proportions. However, this material is a high-hardness metal-based material that cannot be flexed, requiring additional space and weight for structural design, making it difficult to apply in the field of image detector heat dissipation. Patent No. CN202110485055.6, "A Method for Preparing a Graphite Film / Metal Composite Thermal Conductive Cable," discloses a method for preparing a graphite film / metal composite thermal conductive cable. Its thermal conductivity is several times that of a copper thermal conductive cable under the same conditions. However, the graphite film is not treated with anti-static treatment, which poses a risk of excess material during engineering applications. Li Chunjiang et al. (Preparation and Application of a Flexible Composite High-Conductivity Thermal Conductive Cable, Aerospace Manufacturing Technology, 2022, 2) disclose a design and preparation method for a flexible composite high-conductivity thermal conductive cable that effectively solves the heat dissipation problem of high-power chips. However, this structure uses screws to connect the thermal cable to the chip flange and structure, which is large in size and weight, and has multiple contact interfaces, resulting in high thermal resistance.

[0004] In summary, current high-performance image detectors mostly use a structural design of aluminum-based silicon carbide flanges and copper heat conductors for heat dissipation and temperature control. However, due to the presence of the interface, the heat transfer resistance is large, and there is room for improvement in both heat dissipation capacity and temperature control accuracy. In addition, this form of structure is relatively complex and heavy, which has certain limitations in actual engineering applications. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the inventors conducted intensive research and provided an aluminum-based silicon carbide substrate type integrated detector thermal conductive component, which uses graphite film instead of copper rope to make the thermal conductive rope to improve the thermal conductivity; the copper end of the traditional thermal conductive rope is removed, and the thermal conductive rope and the aluminum-based silicon carbide flange are integrally formed using high-temperature brazing and pressing molding technology, thereby reducing the contact thermal resistance of the heat dissipation link while reducing the weight of the structural component.

[0006] The technical solutions provided by the present invention are as follows:

[0007] In a first aspect, an aluminum-based silicon carbide substrate-type integrated detector thermal conductive component includes a graphite film thermal conductive cable and a cold end terminal;

[0008] The graphite film heat conducting cable consists of multiple layers of stacked graphite films, with a hot end and a cold end at the two ends respectively;

[0009] The hot end of the graphite film thermal cable is directly connected to the aluminum-based silicon carbide substrate detector flange by brazing;

[0010] The cold end of the graphite film heat conducting cable is fixed in the cold end terminal, and the cold end terminal is firmly connected to the cold source to realize heat dissipation.

[0011] In combination with the first aspect, a boss is designed on the aluminum-based silicon carbide substrate detector flange at the position where the thermal cable is connected. The middle of the boss is milled out to form an empty groove, and the graphite film thermal cable is welded to the upper and lower walls and both side walls of the empty groove through solder.

[0012] In combination with the first aspect, the height of the empty groove is 0.1 to 0.15 mm greater than the thickness of the thermal cable after compression molding, and the distance between the inner walls on both sides of the empty groove is 0.1 to 0.3 mm greater than the thickness of the thermal cable after compression molding.

[0013] In combination with the first aspect, the brazing filler metal used for brazing the hot end of the graphite film thermal cable and the aluminum-based silicon carbide substrate detector flange includes the following raw materials in parts by mass:

[0014]

[0015] In combination with the first aspect, the graphite film thermal cable has an intermediate section between the cold end and the hot end, and the outer surface of the intermediate section is coated with copper foil and polyimide film in sequence.

[0016] In a second aspect, a method for processing an aluminum-based silicon carbide substrate-type integrated detector thermal conductive component comprises the following steps:

[0017] Lay multiple layers of graphite film on top of each other and trim the four sides to obtain a graphite film thermal cable;

[0018] The outer surface of the hot end of the graphite film heat conducting cable is coated with brazing material and then extended into the empty groove machined on the aluminum-based silicon carbide substrate detector flange. The gap between the hot end of the graphite film heat conducting cable and the top and both side walls of the empty groove is filled with brazing material.

[0019] The outer surface of the cold end of the graphite film heat conducting cable is coated with solder and then inserted into the cold end terminal. The gap between the cold end of the graphite film heat conducting cable and the cold end terminal is filled with solder.

[0020] Use a brazing press to pressure braze the hot end of the graphite film thermal cable, the aluminum-based silicon carbide substrate detector flange, the cold end of the graphite film thermal cable and the cold end terminal to complete the processing of the thermal conductive component.

[0021] The aluminum-based silicon carbide substrate integrated detector thermal conductive component provided by the present invention has the following beneficial effects:

[0022] (1) Significantly reduced thermal resistance. The hot end of the graphite film thermal cable is directly connected to the aluminum-based silicon carbide substrate detector flange by brazing, eliminating the additional hot end head, successfully reducing the heat transfer interface and lowering the contact thermal resistance. Compared with traditional thermal conductive components, the thermal resistance is significantly reduced, effectively improving the heat transfer efficiency.

[0023] (2) Weight reduction. The aluminum-based silicon carbide substrate detector flange serves as both a hot end and a carrier for the image detector. Low-density graphite film replaces the traditional copper heat conductor, reducing the number of hot ends in the heat conductor structure. This alternative not only reduces thermal resistance but also reduces component weight, improving integration and operability.

[0024] (3) Improved reliability and mechanical properties. The proposed high-temperature brazing and pressing molding preparation technology ensures a good connection between the aluminum-based silicon carbide substrate detector flange and the graphite film conductive belt, abandoning the form of screw connection, reducing weight while maintaining good mechanical properties and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of aluminum-based silicon carbide substrate integrated thermal cable;

[0026] Figure 2 Schematic diagram of the cross section of a high thermal conductivity graphite film thermal cable;

[0027] Figure 3 It is a pressurized heating brazing molding system.

[0028] Explanation of Figure Numbers

[0029] 1-Copper foil and polyimide film; 2-Graphite film; 3-Aluminum-based silicon carbide substrate detector flange; 4-Boss; 5-Graphite film thermal conductor; 6-Cold end; 7-Image detector. DETAILED DESCRIPTION

[0030] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0031] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0032] The present invention provides an aluminum-based silicon carbide material integrated detector thermal conductive component, including a graphite film thermal conductive cable and a cold end head. The hot end of the graphite film thermal conductive cable is directly welded to the aluminum-based silicon carbide substrate detector flange using high-temperature brazing and pressing molding technology. The cold end of the graphite film thermal conductive cable is fixed in the cold end head, and the cold end head is in contact with a cold source to implement heat dissipation.

[0033] A high-thermal-conductivity graphite film thermal cable is designed based on considerations of heat dissipation, size, and structural shape. Carbon materials with a thermal conductivity greater than 1000 W / (m·K), such as methane, are selected. High-purity carbon powder is prepared through chemical vapor deposition (CVD). This carbon powder is then pressed into a film to create a graphite film. Multiple layers of micron-sized graphite films are stacked to form the graphite film thermal cable.

[0034] Multilayer thermally conductive films 2 are stacked into sheets (the specific thickness can be determined according to the required heat transfer) to improve the heat transfer efficiency. The thermal conductivity of the thermally conductive rope made of this material reaches 1000-1200W / (m·K) along the heat transfer direction, while the thermal conductivity of traditional copper thermally conductive ropes is about 350W / (m·K). In comparison, graphite film thermally conductive ropes have excellent thermal conductivity, can effectively reduce thermal resistance, and improve the temperature control accuracy of the probe. At the same time, graphite film materials are lighter in density and softer in texture, so they have greater engineering application prospects.

[0035] The size of the graphite film thermal cable can be adjusted according to actual needs, and the four sides can be trimmed evenly. A layer of copper foil is tightly wrapped around the middle section of the graphite film for protection.

[0036] The high-thermal conductivity graphite film thermal cable is efficiently connected to the aluminum-based silicon carbide detector flange using high-temperature compression molding technology. Specifically, a boss 4 is designed at the location on the aluminum-based silicon carbide detector flange 3 where the thermal cable is connected. The center of the boss 4 is milled to form a slot, and the graphite film thermal cable is welded to the upper and lower walls and both sides of the slot using brazing filler metal. The slot is sized to accommodate the hot end of the graphite film thermal cable 5. The slot height is 0.1 to 0.15 mm greater than the thickness of the thermal cable after compression molding, and the distance between the inner walls of the slot is 0.1 to 0.3 mm greater than the thickness of the thermal cable after compression molding, to fully fill the slot with brazing filler metal.

[0037] After applying solder to the hot end of the graphite film thermal cable, insert it into the reserved slot in the flange, with a depth no less than the slot depth (allowing for no more than 5mm of exposed cable). The cable's thickness should be as close as possible to the slot height to minimize compression during subsequent pressurization. If a gap exceeding 0.15mm remains at the slot height, add additional thermal film to fill it. If a significant gap remains in the slot after assembly, add a small piece of thermal film (with an area as close to the boss size as possible) to fill the gap.

[0038] The cold end of the graphite film heat conducting cable is coated with brazing material and then extended into the inner cavity of the cold end terminal 6. The cold end terminal 6 can be made of aluminum-based silicon carbide terminal or copper terminal, etc., preferably aluminum-based silicon carbide terminal.

[0039] A method for brazing aluminum-based silicon carbide materials and graphite film thermal cables has not yet been reported, and conventional brazing fillers, such as copper-based fillers, are difficult to achieve a secure connection between the two. Therefore, after extensive research, the inventors have identified a new aluminum-based brazing filler metal suitable for brazing aluminum-based silicon carbide materials and graphite film thermal cables. This brazing filler metal comprises the following raw materials in parts by weight:

[0040]

[0041] The raw material composition selection and dosage ratio of aluminum-based brazing filler metals affect the welding strength. If the above composition selection and dosage ratio are deviated, the aluminum-based silicon carbide material and the graphite film thermal conductive cable cannot be firmly connected.

[0042] During brazing, the entire thermal assembly and the aluminum-based silicon carbide detector flange are mounted on a fixture to ensure the correct positioning of the components. The components are then placed on a brazing press for pressure brazing. The key to the brazing process is determining parameters such as the brazing temperature, pressurization pressure, and hold time based on the brazing material to ensure weld quality, avoid internal cavities, and effectively improve the thermal conductivity of the assembly.

[0043] Depending on the selected solder, the soldering temperature is 450-500°C, the pressurization pressure is 60-75 MPa, and the holding time is 20-25 minutes.

[0044] After brazing is completed, the original protective copper foil is removed and the overflowed solder is cleaned. A new 25μm to 50μm thick copper foil is coated on the surface of the graphite film thermal conductor in turn, and a 25μm thick polyimide film 1 is pasted. GD414 silicone rubber is used to glue the edges and corners of the polyimide film. The copper foil plays a role in protecting the graphite film from powder loss and uniform heat dissipation, and the polyimide film plays a role in insulation and protection. Figure 2 .

[0045] Figure 1This is an integrated thermally conductive component based on an aluminum-based silicon carbide substrate, formed after welding. The image detector 7 is bonded to the hollow slot of the aluminum-based silicon carbide detector flange using silicone rubber. Heat from the detector is transferred to the aluminum-based silicon carbide detector flange, where it is then effectively transferred to the cold end via graphite film thermal cables. The cold end is designed with a mechanical interface to a heat sink, such as a heat sink, to achieve a secure connection between the components.

[0046] The following specific examples illustrate the structure and processing method of the heat conducting component of the present invention.

[0047] 100 layers of 25μm-thick graphite film are stacked together and trimmed to create a graphite film thermal cable. The middle section of the graphite film thermal cable is wrapped with a layer of copper foil for protection.

[0048] The outer surface of the hot end of the graphite film thermal cable is coated with brazing material and then extended into the empty groove obtained by machining the aluminum-based silicon carbide substrate detector flange. The penetration length is not less than the depth of the empty groove (the thermal cable is allowed to have an exposed length of no more than 5mm); the gap between the graphite film thermal cable and the top and both side walls of the empty groove is filled with brazing material.

[0049] The cold end of the graphite film heat conducting cable is coated with brazing material and then inserted into the inner cavity of the cold end head. The gap between the cold ends is filled with brazing material. The cold end head adopts aluminum-based silicon carbide end head. The composition of the cold end brazing material is the same as that of the hot end brazing material. The brazing material includes the following raw materials by weight:

[0050]

[0051]

[0052] Install the entire heat conducting assembly and the aluminum-based silicon carbide substrate detector flange on the fixed fixture, and use a brazing press to perform pressure brazing of the cold end and the hot end, see Figure 3 The welding process parameters are: welding temperature of 500℃, pressurization pressure of 70MPa, and holding time of 25min.

[0053] After brazing is completed, the original protective copper foil is removed and the overflowed solder is cleaned. A new 50μm thick copper foil is coated on the surface of the graphite film thermal cable, and a 25μm thick polyimide film 1 is pasted (with its own acrylic hot melt adhesive for adhesion). GD414 silicone rubber is used to glue the edges and corners of the polyimide film.

[0054] The welding effect of the rear end of brazing was tested. The empty groove between the graphite film thermal cable and the detector flange was filled with solder. The solder thickness of the upper part of the graphite film thermal cable was 0.1mm, the solder thickness of the lower part was 0.05mm, and the solder thickness on both sides was 0.15mm and 0.15mm.

[0055] According to the invented aluminum-based silicon carbide substrate integrated detector thermal conductive component method, a thermal conductive component with a thermal conductive cable width of 44mm, a length of 24mm, and a thickness of 2.5mm was processed. After vacuum thermal test, the heat load was 3.0W, and the equivalent thermal conductivity of the thermal conductive component (between the detector flange and the cold end) was not less than 1.0W / K, with excellent thermal conductivity.

[0056] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

[0057] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. An aluminum-based silicon carbide substrate type integrated detector thermal conductive component, characterized in that: Including graphite film heat conduction cable and cold end terminal; The graphite film heat conducting cable consists of multiple layers of stacked graphite films, with a hot end and a cold end at the two ends respectively; The hot end of the graphite film thermal cable is directly connected to the aluminum-based silicon carbide substrate detector flange by brazing; The cold end of the graphite film heat conducting cable is fixed in the cold end terminal, and the cold end terminal is firmly connected to the cold source to realize heat dissipation.

2. The aluminum-based silicon carbide substrate integrated detector thermal conductive component according to claim 1, characterized in that: The thermal conductivity of the graphite film heat-conducting cable along the heat transfer direction reaches above 1000 W / (m·K).

3. The aluminum-based silicon carbide substrate integrated detector thermal conductive component according to claim 1, characterized in that: A boss is designed on the aluminum-based silicon carbide substrate detector flange at the position where the thermal cable is connected. The middle of the boss is milled out to form an empty groove. The graphite film thermal cable is welded to the upper and lower walls and both side walls of the empty groove through solder.

4. The aluminum-based silicon carbide substrate integrated detector thermal conductive component according to claim 3, characterized in that: The height of the empty groove is 0.1 to 0.15 mm greater than the thickness of the heat-conducting cable after compression molding, and the distance between the inner walls on both sides of the empty groove is 0.1 to 0.3 mm greater than the thickness of the heat-conducting cable after compression molding.

5. The aluminum-based silicon carbide substrate integrated detector thermal conductive component according to claim 1, characterized in that: The brazing filler metal used for brazing the hot end of the graphite film thermal cable and the aluminum-based silicon carbide substrate detector flange includes the following raw materials in parts by mass: 100 parts of aluminum; 20-35 parts of silicon; 5-10 parts of magnesium; 5 to 10 parts of zinc.

6. The aluminum-based silicon carbide substrate integrated detector thermal conductive component according to claim 1, characterized in that: The middle section is located between the cold end and the hot end of the graphite film heat conducting cable, and the outer surface of the middle section is covered with copper foil and polyimide film in sequence.

7. A method for processing the aluminum-based silicon carbide substrate integrated detector thermal conductive component according to any one of claims 1 to 6, characterized in that: The steps include: Lay multiple layers of graphite film on top of each other and trim the four sides to obtain a graphite film thermal cable; The outer surface of the hot end of the graphite film heat conducting cable is coated with brazing material and then extended into the empty groove machined on the aluminum-based silicon carbide substrate detector flange. The gap between the hot end of the graphite film heat conducting cable and the top and both side walls of the empty groove is filled with brazing material. The outer surface of the cold end of the graphite film heat conducting cable is coated with solder and then inserted into the cold end terminal. The gap between the cold end of the graphite film heat conducting cable and the cold end terminal is filled with solder. Use a brazing press to pressure braze the hot end of the graphite film thermal cable, the aluminum-based silicon carbide substrate detector flange, the cold end of the graphite film thermal cable and the cold end terminal to complete the processing of the thermal conductive component.

8. According to the method for processing the aluminum-based silicon carbide substrate integrated detector thermal conductive component of claim 7, the process parameters of the pressure brazing include: The welding temperature is 450-500°C, the pressurization pressure is 60-75 MPa, and the holding time is 20-25 minutes.

9. The method for processing the aluminum-based silicon carbide substrate integrated detector thermal conductive component according to claim 7, further comprising: After brazing is completed, clean the overflowed solder, wrap the middle section of the graphite film thermal cable with copper foil and polyimide film in sequence, and reinforce the edges and corners of the polyimide film with silicone rubber glue.

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