CN116075124A

CN116075124A - Manufacturing method of high-heat-conductivity flexible heat-conducting belt and high-heat-conductivity flexible heat-conducting belt

Info

Publication number: CN116075124A
Application number: CN202211682477.3A
Authority: CN
Inventors: 王安源; 郑敏信; 魏鑫; 郭伟; 刘瑞姣
Original assignee: China Academy of Aerospace Aerodynamics CAAA
Current assignee: China Academy of Aerospace Aerodynamics CAAA
Priority date: 2022-12-26
Filing date: 2022-12-26
Publication date: 2023-05-05

Abstract

The invention discloses a manufacturing method of a high-heat-conductivity flexible heat-conducting belt and the high-heat-conductivity flexible heat-conducting belt, which comprises the following steps: a rigid terminal and a flexible segment connected to the rigid terminal. Aiming at the defects of large weight, poor flexibility and the like of the traditional metal heat dissipation plate, the novel carbon material graphene film and metal copper are adopted to manufacture the heat conduction belt with simple structure, light weight, thin thickness, good flexibility, easy processing and good heat conductivity. The two ends of the heat conduction belt are respectively matched with the high-temperature and low-temperature areas to form a flexible heat path, so that heat of the high-heating-value part is quickly transferred away, and the heat conduction belt has obvious advantages in the aspects of heat dissipation of electronic equipment in space and with relative motion.

Description

Manufacturing method of high-heat-conductivity flexible heat-conducting belt and high-heat-conductivity flexible heat-conducting belt

Technical Field

The invention relates to the technical field of thermal control, in particular to an ultralight ultrathin high-heat-conductivity flexible heat conduction belt design method and a heat conduction belt manufactured by the same.

Background

The high integration of electronic devices can cause serious heat accumulation problems, especially in space environments, heat is difficult to transfer away in an air convection mode, and heat can only be transferred to a device shell or a radiation panel in a heat transfer mode and then transferred to the environment in a radiation mode. The equipment such as a detector, a nano satellite and the like has strict requirements on weight and volume, and moving parts possibly exist, and the traditional soaking plates are made of metal materials, so that the weight is relatively large and the flexibility is poor.

For the occasions with complex and limited space and relative movement among parts, a flexible and bendable low-thermal-resistance structure is needed to connect a heating part and a heat dissipation part, heat is quickly transferred, the temperature of a large-power consumption area can be reduced, the whole isothermal of the equipment is facilitated, and the thermal deformation is reduced.

The information disclosed in the background section of the invention is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

In order to solve the problems, the novel high-performance carbon material graphene film is applied to the field of heat dissipation, and the problem that the welding difficulty of the material and metal is high is solved. The designed heat conduction belt has light weight, thin thickness and small thermal resistance, can well meet the space and weight requirements, has excellent flexibility, can be bent during assembly, and can rapidly transfer heat between parts moving relatively.

In order to achieve the above object, the present invention provides a high heat conduction flexible heat conduction tape, comprising a rigid terminal and a flexible section connected with the rigid terminal.

Further, the rigid terminal is a metal copper sheet.

Further, the flexible segment is a flexible graphene film.

Further, ag-Cu-Ti brazing filler metal is filled between the rigid terminal and the flexible heat conduction band.

Further, the flexible heat conduction band is a flexible graphene film with a double-layer structure.

According to another aspect of the present invention, there is provided a method of manufacturing a high thermal conductive flexible thermal conductive tape, comprising:

placing one end of the flexible graphene film in contact with a copper sheet, filling Ag-Cu-Ti brazing filler metal in the middle of the flexible graphene film, and pressing the upper part of the copper sheet by using a pressing block;

and placing the placed integral structure in a vacuum brazing furnace for welding.

Further, the temperature of the vacuum brazing process adopts three sections of heating, heat preservation and cooling: raising the temperature to 860 ℃ at the heating rate of 10 ℃/min, preserving the temperature for 15min, and then cooling to room temperature along with the furnace.

Further, the flexible graphene film is of a double-layer structure, and is obtained by bending a single-layer graphene film into a ring and then flattening the single-layer graphene film.

Further, two ends of the single-layer graphene film are bent into a ring shape in a butt joint mode and folded and flattened, and the butt joint position is located on the upper side of one flattened end.

Further, the butt joint of the flexible graphene film and the other symmetrical end are respectively placed in contact with the copper sheet.

Aiming at the defects of large weight, poor flexibility and the like of the traditional metal heat dissipation plate, the novel carbon material graphene film and metal copper are adopted to manufacture the heat conduction belt with simple structure, light weight, thin thickness, good flexibility, easy processing and good heat conductivity. The two ends of the heat conduction belt are respectively matched with the high-temperature and low-temperature areas to form a flexible heat path, so that heat of the high-heating-value part is quickly transferred away, and the heat conduction belt has obvious advantages in the aspects of heat dissipation of electronic equipment in space and with relative motion.

The method and apparatus of the present invention have other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the present invention.

Drawings

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the invention.

Fig. 1 is a schematic diagram of heat transfer from a thermally conductive strip according to an embodiment of the present invention.

Fig. 2 is a structural design of a heat conduction band according to an embodiment of the present invention.

Fig. 3 is a graph of vacuum brazing temperature variation according to an embodiment of the present invention.

Reference numerals:

1 flexible section, 2, rigid terminal, 3 graphene film, 4 copper sheet, 5 foil and 6 butt joint.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention are described below, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The invention discloses a design method of an ultrathin ultralight high-heat-conductivity flexible heat-conducting strip, wherein two ends of the heat-conducting strip are formed by vacuum brazing of graphene films and metal copper and are used for forming connection fit with a heat dissipation part, and the middle section is a double-layer graphene film.

The high-performance carbon material has been rapidly developed in recent years, and is widely applied in the field of heat dissipation, and the high-heat-conductivity graphite flake has good effect in heat dissipation of electronic products such as mobile phones. The novel carbon material graphene film adopts a production process of stacking graphene layer by layer, has the characteristic of high orientation, retains the ultrahigh thermal conductivity in the graphene surface as much as possible, and has the advantages of thin thickness, bending property, excellent thermal conductivity and wide application prospect.

The method of the invention uses a novel material graphene film, solves the problem of high welding difficulty between the material and metal, and uses an annular double-layer structure to improve the heat conduction performance. Compared with the existing graphite film heat conduction band, the heat conduction band prepared by the method has the advantages of light weight, thin thickness, excellent heat conduction performance, better flexibility, stronger applicability and simple batch production process, and can be applied to the field of heat dissipation of electronic circuits and moving parts.

The invention is further described below with reference to the drawings and specific examples, which are not intended to be limiting. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

Example 1

As shown in fig. 1, the present embodiment provides a high-heat-conductivity flexible heat-conducting tape, which includes a rigid terminal 2 and a flexible section 1 connected to the rigid terminal 2.

The heat is input from one end of the rigid terminal 2, and is output from the other end of the rigid terminal 2 through the middle flexible section 1. The rigid terminals 2 at the two ends are used for forming low thermal resistance fit with the heat conduction equipment.

As shown in fig. 2, in this embodiment, the rigid terminal 2 uses a copper sheet 4, which has high thermal conductivity, and can be connected to the surface of the heat conduction device by low-temperature soldering or mechanical riveting, and the middle flexible section 1 uses a graphene film 3 with high in-plane thermal conductivity, so that the thermal resistance in the long-distance heat transfer process can be reduced as much as possible, and a double-layer structure is adopted, which is equivalent to forming a double-layer heat path at the cold and hot ends, so that the heat transfer efficiency is further improved. The rigid terminal 2 and the middle flexible section 1 are connected in a vacuum active brazing mode, and the heat conduction performance of the joint is improved by controlling the welding process.

A foil 5, in this embodiment an Ag-Cu-Ti foil, is arranged between the copper sheet 4 and the graphene film 3. The foil 5 is used as a brazing filler metal, and the graphene film 3 and the copper sheet 4 are subjected to high-temperature vacuum brazing to form a rigid terminal 2 which is matched with a heat transfer surface. The Ag-Cu-Ti brazing filler metal is a carbon-philic brazing filler metal, has good wettability to the surface of the graphene film, and can form a copper/graphene film joint with high strength, low thermal resistance and thermal matching.

As shown in fig. 2, the two ends of the single-layer graphene film 3 are butt-bent into a ring shape, and folded and flattened, so that the butt joint 6 is located at the upper side of one flattened end. And placing the butt joint 6 of the flexible graphene film 3 in contact with the copper sheet 4.

Example two

The embodiment provides a manufacturing method of a high-heat-conductivity flexible heat-conducting belt, which comprises the following steps:

placing one end of the flexible graphene film in contact with a copper sheet, filling an Ag-Cu-Ti foil in the middle, and pressing the upper part of the copper sheet by using a pressing block;

Preferably, before contact placement, the surface dust of the graphene film 3 is wiped with alcohol cotton, and as shown in fig. 2, two ends of the single-layer graphene film 3 are butt-bent into a ring shape and folded and flattened, so that the butt joint 6 is on the upper side of one flattened end.

Preferably, the surface of the copper sheet 4 is polished with fine sand paper before contact placement, the surface oxide layer thereof is removed, and alcohol cotton is used for wiping. The Ag-Cu-Ti foil 5 was cut to a size slightly smaller than the copper 4, and the surface dust was wiped with alcohol cotton.

After the materials are prepared, the butt joint 6 of the flexible graphene film 3 and the other symmetrical end are placed in contact with the copper sheet 4, ag-Cu-Ti brazing filler metal is filled in the middle of the butt joint, and a pressing block is used for pressing the upper part of the copper sheet 4; and (3) placing the placed integral structure in a vacuum brazing furnace, heating to 860 ℃ at a heating rate of about 10 ℃/min, preserving heat for 15min, and cooling to room temperature along with the furnace, wherein the process is as shown in figure 3, so as to obtain the integral welding piece of the heat conducting belt.

The rigid terminal 2 of the embodiment is a three-layer composite structure obtained by vacuum brazing of a copper sheet 4, an Ag-Cu-Ti foil 5 and a graphene film 3. The graphene film 3 is a flexible material with very high in-plane thermal conductivity, and has small long-distance thermal conductivity and thermal resistance, and is an excellent material for the middle flexible section, and if the graphene film 3 is directly glued on the heat transfer surface, the thermal resistance of the glued joint is relatively large, so that the thermal conductivity of the joint is considered to be improved by a welding mode in the embodiment.

However, the welding requirements of the carbon materials are severe, the carbon materials are difficult to melt and are easy to oxidize when heated in the air, so that a welding mode of vacuum brazing is selected in the design, ag-Cu-Ti foil 5 is used as brazing filler metal, and high-temperature vacuum brazing graphene 3 and copper sheet 4 form a rigid terminal 2 which is matched with a heat transfer surface. The Ag-Cu-Ti brazing filler metal is a carbon-philic brazing filler metal, has good wettability to the surface of the graphene film, and can form a copper/graphene film joint with high strength, low thermal resistance and thermal matching.

The heat transfer capability of the flexible section single-layer graphene film 3 is limited, but because of the excellent flexibility, the graphene film 3 is bent into a ring and then flattened to obtain a ribbon structure of the double-layer graphene film, then copper sheets 4 are welded at two ends, and the butt joint 6 of the annular graphene film is just connected together by utilizing the welding of the graphene film 3 and the copper sheets 4. The whole heat conduction band is additionally provided with a heat passage between the cold end and the hot end under the condition of not adding any additional heat resistance and complex operation procedure, so that the heat conduction performance of the heat conduction band can be further improved.

In this embodiment, the vacuum brazing process is three stages, namely a temperature rising stage, a holding stage and a temperature falling stage, the maximum temperature is 860 ℃, the holding time is 15min, and the brazing filler metal needs to be ensured to be completely melted and wet the whole welding seam. However, the temperature cannot be too high, and the heat preservation time cannot be too long, because the welding piece is relatively thin, the temperature is too high, and the welding is easy to penetrate; and secondly, the temperature increase can lead to more vigorous reaction in the welding process, the range of a heat affected zone is increased, the range of an alloy zone of a welded joint is increased, and the boundary between phases is also increased, so that the heat conduction performance of the joint is reduced.

According to a modification, copper has excellent heat conductivity, certain rigidity, a plurality of matching connection modes with the heat transfer surface and low price, the graphene film 3 and the heat transfer surface can be riveted to form pressure contact matching through punching on the rigid terminal 2, if the heat transfer surface has higher requirements, such as a ceramic circuit substrate and the like, the punching is inconvenient, the high temperature cannot be born, and a low-temperature brazing technology of copper materials can be utilized to enable the rigid end and the graphene film 3 to form a low-thermal resistance joint for connection.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described.

Claims

1. A high thermal conductivity flexible thermal conductive tape comprising rigid terminals and flexible segments connected to the rigid terminals.

2. The flexible conductive strip of claim 1, wherein the rigid terminal is a sheet of copper.

3. The high thermal conductivity flexible thermal tape of claim 1, wherein the flexible segment is a flexible graphene film.

4. The flexible thermal tape of claim 1, wherein Ag-Cu-Ti solder is filled between the rigid terminals and the flexible thermal tape.

5. The flexible thermal conductive tape of claim 1, wherein the flexible thermal conductive tape is a bilayer structured flexible graphene film.

6. The manufacturing method of the high-heat-conductivity flexible heat-conducting belt is characterized by comprising the following steps of:

7. The method for manufacturing the high-heat-conductivity flexible heat-conducting strip according to claim 6, wherein the vacuum brazing process temperature adopts three steps of heating, heat preservation and cooling: raising the temperature to 860 ℃ at the heating rate of 10 ℃/min, preserving the temperature for 15min, and then cooling to room temperature along with the furnace.

8. The method for manufacturing a flexible heat conductive tape according to claim 6, wherein the flexible graphene film has a double-layer structure, and is obtained by bending a single-layer graphene film into a ring and then flattening the single-layer graphene film.

9. The method for manufacturing a flexible heat conductive tape with high heat conductivity according to claim 8, wherein the two ends of the single-layer graphene film are butt-jointed and bent into a ring shape and folded and flattened, and the butt joint is positioned on the upper side of one flattened end.

10. The method of manufacturing a flexible thermal tape of claim 9, wherein the butt joint of the flexible graphene film and the symmetrical other end are placed in contact with the copper sheet, respectively.