Welding method of a heat plate and a metal heat pipe

Abstract

This invention relates to a welding method for a heat spreader plate and a metal heat pipe, comprising the following steps: a cylindrical portion is integrally formed by protruding upwards from the upper end of the outer shell of the heat spreader plate corresponding to the periphery of the mounting hole; a stainless steel ring is fitted around the periphery of the cylindrical portion; the lower ends of both the metal heat pipe and the second capillary core are simultaneously inserted into the first inner cavity through the mounting hole; an annular brazing filler metal is fitted around the periphery of the cylindrical portion and stacked on top of the stainless steel ring to obtain a workpiece; the workpiece is placed in a vacuum brazing furnace for heating; during the heating process, the inner wall of the cylindrical portion is tightly fitted to the outer wall of the metal heat pipe, and the molten annular brazing filler metal is squeezed under clamping force, which greatly improves its wettability and prevents incomplete welding or local lack of fusion; during the cooling and solidification stage, the molten annular brazing filler metal is compacted during solidification, resulting in a higher weld density, no shrinkage cavities or porosity defects, and higher weld mechanical strength.

Description

Technical Field

[0001] This invention relates to the technical field of welding methods for heat spreaders and metal heat pipes, and in particular to a welding method for heat spreaders and metal heat pipes. Background Technology

[0002] With the rapid development of electronic devices, their operating capabilities are becoming increasingly powerful, generating more and more heat. Therefore, vapor chambers are widely used as heat sinks in high-power or highly integrated electronic products. When used properly, it can be simply understood as a component with a very high thermal conductivity.

[0003] Vapor chambers offer several advantages: low space requirements, large contact area, and rapid thermal response. These characteristics can be applied to heat sinks to reduce heat diffusion resistance and hot spots. Vapor chambers are categorized into 2D and 3D types. 2D vapor chambers are plate-type heat sinks, achieving heat conduction on a two-dimensional surface. 3D vapor chambers embed heat pipes within the heat sink, distributing the chip's heat evenly across the heat sink substrate or fins. Since the heat pipes are connected to the fins, heat can be more effectively dissipated into the air through the entire heat sink, achieving heat conduction on a three-dimensional surface.

[0004] The existing method for installing heat pipes and radiators in 3D vapor chambers typically involves directly connecting the heat pipes to the raised "nozzle structure" on the radiator's top cover, applying solder directly to the connection seam, and then performing vacuum gas shielded welding. This method has the following drawbacks: the molten solder rises excessively due to capillary action, flowing into and clogging the tiny vapor channels inside the radiator or heat pipes. Furthermore, the lack of guidance during assembly easily leads to eccentricity and misalignment, increasing welding difficulty and affecting product quality.

[0005] Therefore, in this patent application, the applicant has carefully studied a welding method for a heat spreader and a metal heat pipe to solve the above problem. Summary of the Invention

[0006] The present invention addresses the shortcomings of the prior art by providing a welding method for a heat spreader and a metal heat pipe. During the heating process, the inner wall of the cylinder is tightly fitted to the outer wall of the metal heat pipe. Furthermore, the molten annular brazing filler metal is compressed under clamping force, which greatly improves its wettability and prevents incomplete welding or local lack of fusion. During the cooling and solidification stage, the molten annular brazing filler metal is compacted during solidification, resulting in a higher weld density, no shrinkage cavities or porosity defects, and higher weld mechanical strength.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for welding a heat spreader to a metal heat pipe includes the following steps: Step S1: Prepare a metal heat pipe, an upper outer shell of a heat spreader plate, and a lower outer shell of a heat spreader plate. The upper outer shell of the heat spreader plate has a mounting hole that runs through its upper and lower sides. The upper end of the upper outer shell of the heat spreader plate is integrally formed with a cylindrical part protruding upwards from the periphery of the mounting hole. A stainless steel ring is fitted around the outer periphery of the cylindrical body, and the stainless steel ring is tightly fitted to the cylindrical body. The lower end of the stainless steel ring abuts against the outer shell of the heat spreader plate, and the upper end face of the stainless steel ring is higher than the upper end face of the cylindrical body. A first inner cavity is formed between the outer shell of the upper heat spreader plate and the lower shell of the heat spreader plate. The mounting hole communicates with the first inner cavity. A first upper capillary, a first lower capillary, and a liquid circulation capillary whose upper and lower ends are respectively connected to the first upper capillary and the first lower capillary are provided in the first inner cavity. The first upper capillary and the first lower capillary are respectively connected to the inner top wall and the inner bottom wall of the first inner cavity. At least one liquid circulation capillary is located directly below the mounting hole. The metal heat pipe has a second inner cavity with an opening at the lower end, and a second capillary core is provided on the inner wall of the second inner cavity. The second capillary core is a hollow structure with a clearance hole at the top and bottom. Step S2: The lower ends of both the metal heat pipe and the second capillary core are simultaneously inserted into the first inner cavity through the mounting hole and abutted against the liquid circulation capillary core located directly below the mounting hole to obtain a pre-assembled assembly. The first inner cavity is connected by the second capillary core to form an annular groove between the inner wall of the stainless steel ring of the second inner cavity, the upper end face of the cylinder, and the outer wall of the metal heat pipe. Step S3: A ring-shaped brazing filler metal is fitted around the outer periphery of the cylinder and stacked on top of the stainless steel ring to obtain the workpiece to be processed. The workpiece to be processed is placed in a vacuum brazing furnace for heating. After heating, the ring-shaped brazing filler metal melts and fills the annular groove and the connection gap between the metal heat pipe and the mounting hole. After cooling, an airtight seal is formed, and the welding of the heat spreader plate and the metal heat pipe is completed.

[0008] As a preferred embodiment, in step S3, the workpiece to be processed is placed in a vacuum brazing furnace and heated at a high temperature of 720 degrees Celsius to 920 degrees Celsius.

[0009] As a preferred embodiment, the upper end face of the mounting hole is formed into a trapezoidal frustum surface that is larger at the top and smaller at the bottom.

[0010] As a preferred embodiment, a support column is provided on the inner bottom wall of the first inner cavity. The first lower capillary and the liquid circulation capillary are respectively provided with a first positioning hole and a second positioning hole. The support column passes through the first positioning hole and the second positioning hole in sequence and abuts against the first upper capillary.

[0011] As a preferred embodiment, the first upper capillary core is provided with a clearance hole. In step S2, the lower ends of the metal heat pipe and the second capillary core pass through the mounting hole and the clearance hole in sequence and extend into the first inner cavity.

[0012] As a preferred embodiment, the lower end face of the stainless steel collar is formed into a trapezoidal frustum, which is smaller at the top and larger at the bottom.

[0013] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it mainly uses a stainless steel ring to fit around the outer periphery of the cylinder. During the heating process, the outer diameter of the cylinder increases due to thermal expansion and contraction, but the stainless steel ring has a small expansion amount and high rigidity, forming a continuous clamping force on the cylinder. This allows the inner wall of the cylinder to fit tightly against the outer wall of the metal heat pipe. In particular, the annular brazing filler melts after heating and fills the annular groove and the connection gap between the metal heat pipe and the mounting hole. Under the clamping force, it is squeezed, which greatly improves its wettability and prevents incomplete welding or local lack of fusion. During the cooling and solidification stage, the sleeve of the cylinder shrinks more than the stainless steel ring, continuously applying inward pressure. The molten annular brazing filler is compacted during the solidification process, resulting in higher weld density, no shrinkage cavities or porosity defects, and higher weld mechanical strength. Secondly, the upper end face of the mounting hole forms a trapezoidal frustum that is larger at the top and smaller at the bottom, which facilitates the guidance of the metal heat pipe during assembly, improves assembly efficiency, and consequently improves subsequent processing efficiency. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the pre-assembled component assembly structure of a preferred embodiment of the present invention.

[0015] Figure 2 This is an exploded view of the pre-assembled components according to a preferred embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of a partial cross-sectional structure of the workpiece to be processed according to a preferred embodiment of the present invention (mainly showing the annular brazing filler metal).

[0017] Icon descriptions included Metal heat pipe 10; second inner cavity 11; second capillary wick 12; The outer shell 21 is on the heat spreader plate; mounting holes 211; Trapezoidal frustum 212; cylindrical body 213; Lower outer casing of heat spreader 22; First inner cavity 23; Support column 231; First upper capillary core 24; clearance hole 241; First lower capillary core 25; First positioning hole 251; Liquid circulation capillary wick 26; second positioning hole 261; Stainless steel ring 30; trapezoidal round table 31; Annular groove 40; 50mm ring-shaped brazing filler metal; 60mm joint gap. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0019] like Figures 1 to 3 As shown, the present invention is a welding method for a heat spreader and a metal heat pipe, comprising the following steps: Step S1: Prepare the metal heat pipe 10, the outer shell 21 of the upper heat spreader, and the lower shell 22 of the heat spreader. The outer shell 21 of the upper heat spreader has a mounting hole 211 that runs vertically through its upper and lower sides. In this embodiment, the upper end surface of the mounting hole 211 forms a trapezoidal frustum 212 that is larger at the top and smaller at the bottom.

[0020] On the heat spreader plate, the upper end face of the outer shell 21 is integrally formed with a cylindrical part 213 protruding upwards corresponding to the periphery of the mounting hole 211, and a stainless steel collar 30 is fitted around the periphery of the cylindrical part 213. In this embodiment, the lower end face of the stainless steel collar 30 is formed with a trapezoidal frustum 31 that is smaller at the top and larger at the bottom.

[0021] The stainless steel collar 30 and the cylindrical body 213 are tightly connected. The lower end of the stainless steel collar 30 abuts against the outer shell 21 on the heat spreader plate, and the upper end face of the stainless steel collar 30 is higher than the upper end face of the cylindrical body 213. A first inner cavity 23 is formed between the outer shell 21 on the upper heat spreader plate and the lower outer shell 22 on the lower heat spreader plate. The mounting hole 211 communicates with the first inner cavity 23. The first inner cavity 23 is provided with a first upper capillary 24, a first lower capillary 25, and a liquid circulation capillary 26 whose upper and lower ends are respectively connected to the first upper capillary 24 and the first lower capillary 25. The first upper capillary 24 and the first lower capillary 25 are respectively connected to the inner top wall and the inner bottom wall of the first inner cavity 23. At least one liquid circulation capillary 26 is located directly below the mounting hole 211.

[0022] In this embodiment, a support column 231 protrudes upward from the inner bottom wall of the first inner cavity 23. The first lower capillary wick 25 and the liquid circulation capillary wick 26 are respectively provided with a first positioning hole 251 and a second positioning hole 261. The support column 231 passes through the first positioning hole 251 and the second positioning hole 261 in sequence and abuts against the first upper capillary wick 24. The first upper capillary wick 24 is provided with an avoidance hole 241.

[0023] The metal heat pipe 10 has a second inner cavity 11 with an opening at the lower end. A second capillary wick 12 is provided on the inner wall of the second inner cavity 11. The second capillary wick 12 has a hollow structure at the top and bottom.

[0024] In step S2, the lower ends of the metal heat pipe 10 and the second capillary wick 12 are simultaneously inserted into the first inner cavity 23 through the mounting hole 211 and abutted against the liquid circulation capillary wick 26 located directly below the mounting hole 211 to obtain a pre-assembled assembly. The first inner cavity 23 is connected to the second inner cavity 11 through the second capillary wick 12. An annular groove 40 is formed between the inner wall of the stainless steel ring 30, the upper end face of the cylinder portion 213, and the outer wall of the metal heat pipe 10.

[0025] Step S3: A ring-shaped brazing filler metal 50 is fitted around the outer periphery of the cylindrical part 213 and stacked on top of the stainless steel ring 30 to obtain the workpiece to be processed. The workpiece to be processed is placed in a vacuum brazing furnace for heating. In this embodiment, the workpiece to be processed is placed in a vacuum brazing furnace and heated at a high temperature of 720 degrees Celsius to 920 degrees Celsius.

[0026] The annular brazing filler metal 50 melts after heating and fills the annular groove 40 and the connection gap 60 between the metal heat pipe 10 and the mounting hole 211. After cooling, it forms an airtight seal, completing the welding of the heat spreader plate and the metal heat pipe.

[0027] An annular brazing filler metal 50 is pre-placed in the annular groove 40. The pre-assembled components are placed in a vacuum brazing furnace and heated at a high temperature of 720 degrees Celsius to 920 degrees Celsius. After heating, the annular brazing filler metal 50 melts and fills the connection gap 60 between the metal heat pipe 10 and the mounting hole 211. After cooling, an airtight seal is formed, completing the welding of the heat spreader plate and the metal heat pipe.

[0028] The key design features of this invention are as follows: It primarily uses a stainless steel ring fitted around the periphery of the cylindrical section. During heating, the outer diameter of the cylindrical section increases due to thermal expansion and contraction, but the stainless steel ring expands only slightly and is highly rigid, creating a continuous clamping force on the cylindrical section. This allows the inner wall of the cylindrical section to tightly adhere to the outer wall of the metal heat pipe. In particular, the annular brazing filler melts after heating and fills the annular groove and the connection gap between the metal heat pipe and the mounting hole. Under the clamping force, it is compressed, significantly improving its wettability and preventing incomplete welding or localized lack of fusion. During the cooling and solidification stage, the sleeve of the cylindrical section contracts more than the stainless steel ring, continuously applying inward pressure. The molten annular brazing filler is compacted during solidification, resulting in a denser weld with no shrinkage cavities or porosity defects, and higher weld mechanical strength. Secondly, the upper end face of the mounting hole forms a trapezoidal frustum that is larger at the top and smaller at the bottom, which facilitates the guidance of the metal heat pipe during assembly, improves assembly efficiency, and consequently improves subsequent processing efficiency.

Claims

1. A method for welding a heat spreader to a metal heat pipe, characterized in that, The steps include the following: Step S1: Prepare a metal heat pipe, an upper outer shell of a heat spreader plate, and a lower outer shell of a heat spreader plate. The upper outer shell of the heat spreader plate has a mounting hole that runs through its upper and lower sides. The upper end of the upper outer shell of the heat spreader plate is integrally formed with a cylindrical part protruding upwards from the periphery of the mounting hole. A stainless steel ring is fitted around the outer periphery of the cylindrical body, and the stainless steel ring is tightly fitted to the cylindrical body. The lower end of the stainless steel ring abuts against the outer shell of the heat spreader plate, and the upper end face of the stainless steel ring is higher than the upper end face of the cylindrical body. A first inner cavity is formed between the outer shell of the upper heat spreader plate and the lower shell of the heat spreader plate. The mounting hole communicates with the first inner cavity. A first upper capillary, a first lower capillary, and a liquid circulation capillary whose upper and lower ends are respectively connected to the first upper capillary and the first lower capillary are provided in the first inner cavity. The first upper capillary and the first lower capillary are respectively connected to the inner top wall and the inner bottom wall of the first inner cavity. At least one liquid circulation capillary is located directly below the mounting hole. The metal heat pipe has a second inner cavity with an opening at the lower end, and a second capillary core is provided on the inner wall of the second inner cavity. The second capillary core is a hollow structure with a clearance hole at the top and bottom. Step S2: The lower ends of both the metal heat pipe and the second capillary core are simultaneously inserted into the first inner cavity through the mounting hole and abutted against the liquid circulation capillary core located directly below the mounting hole to obtain a pre-assembled assembly. The first inner cavity is connected by the second capillary core to form an annular groove between the inner wall of the stainless steel ring of the second inner cavity, the upper end face of the cylinder, and the outer wall of the metal heat pipe. Step S3: A ring-shaped brazing filler metal is fitted around the outer periphery of the cylinder and stacked on top of the stainless steel ring to obtain the workpiece to be processed. The workpiece to be processed is placed in a vacuum brazing furnace for heating. After heating, the ring-shaped brazing filler metal melts and fills the annular groove and the connection gap between the metal heat pipe and the mounting hole. After cooling, an airtight seal is formed, and the welding of the heat spreader plate and the metal heat pipe is completed.

2. The welding method of the heat spreader and the metal heat pipe according to claim 1, characterized in that: In step S3, the workpiece to be processed is placed in a vacuum brazing furnace and heated at a high temperature of 720 degrees Celsius to 920 degrees Celsius.

3. The welding method of the heat spreader and the metal heat pipe according to claim 1, characterized in that: The upper surface of the mounting hole forms a trapezoidal frustum, which is larger at the top and smaller at the bottom.

4. The welding method of the heat spreader and the metal heat pipe according to claim 1, characterized in that: The inner bottom wall of the first inner cavity is provided with a support column protruding upwards. The first lower capillary and the liquid circulation capillary are respectively provided with a first positioning hole and a second positioning hole. The support column passes through the first positioning hole and the second positioning hole in sequence and abuts against the first upper capillary.

5. The welding method of the heat spreader and the metal heat pipe according to claim 1, characterized in that: The first upper capillary core has a clearance hole. In step S2, the lower ends of the metal heat pipe and the second capillary core pass through the mounting hole and the clearance hole in sequence and extend into the first inner cavity.

6. The welding method of the heat spreader and the metal heat pipe according to claim 1, characterized in that: The lower end face of the stainless steel collar forms a trapezoidal frustum, which is smaller at the top and larger at the bottom.

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