Preparation method of copper-molybdenum copper-copper multilayer composite heat sink material

Abstract

The invention relates to the technical field of preparation of composite heat sink materials, and discloses a preparation method of a copper-molybdenum-copper-copper multi-layer composite heat sink material, which comprises the following steps: S1, preparing two oxygen-free copper plates, a molybdenum copper plate and two sheet-shaped welding fluxes with corresponding sizes, s2, the copper plate, the welding flux, the molybdenum copper plate, the welding flux and the copper plate are stacked from bottom to top; the thermal expansion coefficient and the thermal conductivity are both within the normal range level, and a large amount of energy consumption cost, time cost and equipment cost are saved; a diffusion welding mode is adopted, and the method is mainly characterized in that production efficiency is high, and energy consumption is low; compared with hot-pressing compounding, the time of welding compounding is greatly shortened, the heating time, the heat preservation time and the cooling time of the hot-pressing compounding are increased by more than 20 hours, the welding compounding does not exceed 8 hours, a large amount of time cost is saved, and the welding temperature is lower than the hot-pressing temperature by more than 20%.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of composite heat sink materials, and in particular to a method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material. Background Art

[0002] Heat sink materials are mainly used in the field of electronic packaging. They provide stable packaging for high-power electronic components and are also responsible for conducting away the large amount of heat they emit, ensuring that their operating temperature is stable within the normal operating range.

[0003] At present, there are basically two ways for domestic and foreign companies to produce CPC. One is hot rolling: rolling uses mechanical meshing to bond the molybdenum copper with pre-proportioned thickness and size to the upper and lower copper sheets, and then hot rolling, warm rolling, and cold rolling until the final finished product thickness. The advantages of this method are simple equipment and high production efficiency, but the utilization rate of raw materials is very low, at about 60%.

[0004] The other is hot pressing composite. The main principle of this method is to squeeze the molybdenum copper sheet and the copper sheet firmly together by heating and pressurizing, so that the copper atoms in the copper sheet and the copper atoms in the molybdenum copper fit closely together to form a continuous copper channel. At the same time, the atoms between molybdenum and copper diffuse to achieve the effect of diffusion welding for composite. The advantages of this method are high material utilization / good composite effect, and it can basically be composited according to the designed size. However, the disadvantages of hot pressing are also obvious. First, the hot pressing cycle is long. Secondly, due to the long-term heat preservation and pressure maintenance, the requirements for the equipment itself are also relatively high. Compared with the rolling mill, it is more expensive and less efficient than the rolling composite method. In order to solve the shortcomings of hot rolling composite and hot pressing composite, improve production efficiency and improve material utilization, a preparation method of copper-molybdenum-copper-copper multilayer composite heat sink material is proposed. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material to solve the problem proposed in the above background technology of solving the shortcomings of hot rolling composite and hot pressing composite, improving production efficiency and improving material utilization.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material, comprising the following steps:

[0007] S1. Prepare two clean oxygen-free copper plates, a molybdenum copper plate, and two pieces of solder flakes of corresponding size without impurities or oxide scale on the surface;

[0008] S2, stacking from bottom to top in the order of copper plate-solder-molybdenum copper plate-solder-copper plate;

[0009] S3, placing a high temperature resistant heavy block on the top layer;

[0010] S4, placed in a heating furnace protected by atmosphere;

[0011] S5, taking out the composited CPC material;

[0012] S6. Perform X-ray flaw detection on the composite CPC material;

[0013] S7. Conduct thermal conductivity and thermal expansion tests on the composite CPC material.

[0014] As a further preferred embodiment of the present technical solution: in S1, the thickness of the two pieces of sheet solder is 0.1-0.02 mm.

[0015] As a further preferred embodiment of the present technical solution: in S2, the stacked copper plate-solder-molybdenum-copper plate-solder-copper plate are fixed to prevent relative sliding between the layers.

[0016] As a further preferred embodiment of the present technical solution: in S3, the weight of the high temperature resistant weight block is 1-20KG, and the stack is appropriately pressurized.

[0017] As a further preferred embodiment of the present technical solution: in S4, the temperature in the heating furnace is 300-1050°C, and the insulation time is 30min-4h.

[0018] As a further preferred embodiment of the present technical solution: in S5, the side and surface of the composite CPC material are subjected to grinding and sandblasting treatment.

[0019] As a further preferred embodiment of the present technical solution: in S6, the composite degree of the composited CPC material is checked by X-ray flaw detection.

[0020] As a further preferred embodiment of the present technical solution: in S4, in the heating furnace, the insulation temperature reaches the melting temperature of the solder but does not reach the melting point of copper and molybdenum-copper alloy. Therefore, the upper and lower metal plates can be welded together after the molten solder cools down. During the insulation process, atomic diffusion will also occur between the solder and the upper and lower plates to be welded, which can produce an effect similar to diffusion welding and make the welding stronger.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Compared with hot-rolled composite, the welding composite method of the present invention is simple, has fewer steps, and has a high material utilization rate, and will not cause cracking due to rolling.

[0023] 2. Compared with hot pressing compound, the welding compound time of the present invention is greatly reduced. The heating time, insulation time and cooling time of hot pressing compound are added together for more than 20 hours, while the welding compound does not exceed 8 hours, which saves a lot of time cost. In addition, the welding temperature is more than 20% lower than the hot pressing temperature.

[0024] 3. The thermal expansion coefficient and thermal conductivity of the present invention are both within the normal range, and a large amount of energy consumption cost, time cost and equipment cost are saved.

[0025] 4. The main feature of diffusion welding is high production efficiency and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of the stacking method of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0030] Example 1

[0031] In the prior art, in order to solve the shortcomings of hot rolling compounding and hot pressing compounding, the production efficiency is improved while improving the material utilization rate.

[0032] See also Figure 1 The present invention provides a technical solution: a method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material, comprising the following steps:

[0033] S1. Prepare two clean oxygen-free copper plates, molybdenum copper plates, and two silver-copper solders of corresponding sizes. The copper block is 50mm*50mm in size and 0.25mm in thickness; the molybdenum copper is Mo70Cu30, 50mm*50mm in size, 1mm in thickness, and the flatness is within 0.03mm; the silver-copper solder is Au72Cu28, 50mm*50mm in size and 0.05mm in thickness; the thickness ratio of copper to molybdenum copper is 1:4:1;

[0034] S2. Place the copper plate-silver-copper solder-molybdenum-copper plate-silver-copper solder-copper plate in layers from bottom to top, and fix them with molybdenum plates around to prevent relative sliding between layers;

[0035] S3. Place a high temperature resistant weight block weighing 3 kg on the top layer and apply appropriate pressure to the stack;

[0036] S4, placed in a heating furnace protected by hydrogen atmosphere, temperature 780 ℃, heat preservation time 2h, in the heating furnace, the heat preservation temperature reaches the melting temperature of the solder but does not reach the melting point temperature of copper and molybdenum copper alloy, so the molten solder can be used to weld the upper and lower metal plates after cooling. During the heat preservation process, atomic diffusion will occur between the solder and the upper and lower plates to be welded, which can produce an effect similar to diffusion welding to make the welding stronger. The solder is selected from silver-copper, gold-tin solder and other solders that can diffuse and dissolve with copper / molybdenum;

[0037] S5. Take out the composite CPC141 material and grind and sandblast the sides and surfaces;

[0038] S6. X-ray flaw detection was performed on the CPC141 after lamination, and it was found that the lamination was basically completed, with no unlaminated area;

[0039] S7. Conduct thermal conductivity and thermal expansion tests. The thermal expansion coefficient is 9.25×10-6 / °C (at 25°C-300°C), and the thermal conductivity is 226W / (m·K).

[0040] Example 2

[0041] See also Figure 1 , which is different from Example 1: the size of the copper block is 100mm*100mm, the thickness is 0.5mm, the size of the molybdenum copper block is 100mm*100mm, the thickness is 2mm, the flatness is within 0.04, the size of the silver copper solder is 100mm*100mm, the thickness is 0.05mm. The weight of the counterweight is 12KG.

[0042] The CPC141 heat sink material with a thermal expansion coefficient of 9.16×10-6 / °C (at 25°C-300°C) and a thermal conductivity of 221 W / (m·K) was prepared.

[0043] Example 3

[0044] See also Figure 1 , which is different from Example 1 and Example 2: the copper block is 100mm*100mm in size and 1mm in thickness, the molybdenum copper block is Mo60Cu40 in size and 100mm*100mm in thickness and 1mm in flatness within 0.04, the silver copper solder is 100mm*100mm in size and 0.05mm in thickness. The weight of the counterweight is 12KG.

[0045] The CPC141 heat sink material with a thermal expansion coefficient of 11.79×10-6 / °C (at 25°C-300°C) and a thermal conductivity of 210 W / (m·K) was prepared.

[0046] Example 4

[0047] See also Figure 1 , which is different from Example 1, Example 2 and Example 3: the copper block has a size of 100mm*100mm and a thickness of 1mm, the molybdenum copper block has a composition of Mo50Cu50, a size of 100mm*100mm, a thickness of 1mm, and a flatness within 0.04, and the silver copper solder has a size of 100mm*100mm and a thickness of 0.05mm. The weight of the counterweight is 12KG.

[0048] The CPC111 heat sink material with a thermal expansion coefficient of 12.86×10-6 / °C (at 25°C-300°C) and a thermal conductivity of 226W / (m·K) was prepared.

[0049] In summary,

[0050]

[0051]

[0052] The melting point of the selected solder is not higher than the melting point of copper 1083℃, and it can at least diffuse atoms between copper and molybdenum to achieve the effect of diffusion welding, such as gold-tin solder and silver-copper solder; the temperature of the heating furnace is above the melting point of the solder and below the melting point of copper, and the heat preservation time is long enough to allow the molten solder to fully diffuse between the upper and lower layers of metal; the number of layers can be 2, 3, 4, 5 or any other number of layers; the two materials of copper-molybdenum-copper-copper can be replaced by any metal material suitable for diffusion welding, and the proportion is not limited; the flatness of the middle core material must be controlled within 0.01mm-0.04mm according to the size of the welding area.

[0053] So far, the embodiments of the present invention have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each component are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in the field can simply change or replace them.

[0054] It should also be noted that, in the specific embodiments of the present invention, unless otherwise indicated, the numerical parameters in this specification and the attached claims are approximate values ​​and can be changed according to the desired characteristics obtained through the content of the present invention. Specifically, all numbers used in the specification and claims to express the size, range conditions, etc. of the composition should be understood to be modified by the term "about" in all cases. In general, the meaning of the expression is to include a change of ±10% in some embodiments, a change of ±5% in some embodiments, a change of ±1% in some embodiments, and a change of ±0.5% in some embodiments by a specific number.

[0055] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or combinations fall within the scope of the present invention.

[0056] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material, characterized in that: The following steps are involved: S1. Prepare two clean oxygen-free copper plates, a molybdenum copper plate, and two pieces of solder flakes of corresponding size without impurities or oxide scale on the surface; S2, stacking from bottom to top in the order of copper plate-solder-molybdenum copper plate-solder-copper plate; S3, placing a high temperature resistant heavy block on the top layer; S4, placed in a heating furnace protected by atmosphere; S5, taking out the composited CPC material; S6. Perform X-ray flaw detection on the composite CPC material; S7. Conduct thermal conductivity and thermal expansion tests on the composite CPC material.

2. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S1, the thickness of the two pieces of solder sheets is 0.1-0.02 mm.

3. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S2, the stacked copper plate-solder-molybdenum copper plate-solder-copper plate are fixed to prevent relative sliding between the layers.

4. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S3, the weight of the high temperature resistant weight block is 1-20KG, and the stack is appropriately pressurized.

5. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S4, the temperature in the heating furnace is 300-1050°C, and the insulation time is 30min-4h.

6. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S5, the side and surface of the composite-finished CPC material are subjected to grinding and sandblasting treatment.

7. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S6, the composite degree of the CPC material after composite is checked by X-ray flaw detection.

8. The method for preparing a copper-molybdenum-copper-copper multilayer composite heat sink material according to claim 1, characterized in that: In S4, in the heating furnace, the insulation temperature reaches the melting temperature of the solder but does not reach the melting point of copper and molybdenum-copper alloy. Therefore, the upper and lower metal plates can be welded together after the molten solder cools down. During the insulation process, atomic diffusion will occur between the solder and the upper and lower plates to be welded, which can produce an effect similar to diffusion welding and make the welding stronger.

Images