TWI435780B - Copper powder, manufacturing method and apparatus thereof and heat dissipater using the same - Google Patents

Description

Copper powder and manufacturing method thereof, manufacturing device and heat sink

The present invention relates to the field of metal powder materials, in particular to a copper powder having a bulk density of less than 2.0 g/cm ³ , a manufacturing method thereof, a manufacturing device and a heat sink having copper powder.

Copper powder is an important raw material for the electronics industry, machinery manufacturing and automotive industry, and the bulk density of copper powder is an important parameter for the performance of copper powder. Different application fields have different requirements for bulk density, such as injection. Molded products require high bulk density copper powder. In some areas (such as heat pipes and hot plates in the scattering industry), copper powder with low bulk density is required. Currently, the commercial copper powder has a bulk density of 2.8. g/cm3-3.8g/cm3, a few companies can produce low-density density copper powder of 2.0g/cm3-2.8g/cm3, which is blank for loose copper powder with density less than 2.0g/cm3. Some high-end products and new products are used to impose restrictions.

At present, methods for producing low bulk density copper powder include electrolysis, conventional water atomization, agglomeration and ball milling. In the electrolysis method, a thick copper plate is used as an anode, and a mixed solution of sulfuric acid and copper sulfate is used as an electrolyte. After electrification, copper powder can be precipitated at the cathode, but the shape of the copper powder obtained by electrolysis is a dendritic structure, and the fluidity is extremely low. In the actual application, it is difficult to fill the powder and other processes. The conventional water atomization method is to use a high-speed pure water to impinge a molten copper liquid stream, to break the copper liquid stream into droplets and then rapidly cool to obtain a metal copper powder, but the atomization water pressure kinetic energy and the cooling of the metal droplets in the production process Rate is difficult to control When it is in the best condition, it is easy to cause spheroidization of metal droplets, so that the bulk density is usually higher than 2.0g/cm3. The agglomeration method is to diffuse and sinter the fine copper powder at a high temperature, thereby obtaining a copper powder which is agglomerated into small particles by small particles, and the copper powder can reduce the bulk density to 2.0-3.0 g according to the different agglomeration process. /cm3, but each powder is composed of many fine powders, which are liable to cause instability of quality and fineness when being sieved, transported or used. As for the ball milling method, the mechanical shape of the powder is used to change the shape of the powder to reduce the bulk density of the powder. However, the shape of the copper powder obtained by this method is flake-shaped (thickness less than 1 micrometer), no fluidity, molding. Extremely poor, and easy to introduce impurities in the production process.

In view of the above problems, it is necessary to provide a new method for manufacturing ultra-low bulk density copper powder to solve the above problems.

The technical problem solved by the present invention is to provide an ultra-low bulk density copper powder and a preparation method thereof, which can produce a copper powder having a bulk density of less than 2.0 g/cm ³ .

The present invention can be realized by the following technical scheme: a copper powder having a bulk density of 0.8 g/cm ³ to 2.0 g/cm ³ and mainly composed of a non-dendritic irregular single-particle copper powder. The surface of the copper powder particles is rough and provided with holes or cracks, and the copper powder has a tap density of 1.2-2.5 g/cm3, which is vibrated and has a porosity of more than 63% after sintering at 980 ° C for 30 minutes.

Further, the fineness of the copper powder is from 18 mesh to 500 mesh.

The invention can also be implemented by the following technical solutions: a heat dissipating component comprising a heat-dissipating body of a metal material and a copper powder layer covering the heat-dissipating body, wherein the copper powder layer has a thickness of 0.2 mm to 10 mm, and the copper powder layer is The bulk density is from 0.8 g/cm ³ to 2.0 g/cm ³ of copper powder, and the copper powder is mainly composed of irregularly shaped single-particle copper powder, and the tap density of the copper powder is 1.2-2.5 g/cm ³ The porosity after tapping and sintering at 980 ° C for 30 minutes is greater than 63%.

Further, the fineness of the copper powder is from 18 mesh to 500 mesh.

Further, the heat dissipating body has a circular tubular shape and is provided with an inner cavity, and the inner cavity is provided with an inner surface, and the copper powder layer is disposed on the inner surface.

Further, the heat dissipation body has a flat shape.

Compared with the prior art, the copper powder manufacturing method and the manufacturing device described in the present invention can produce copper powder with complicated shape and variable shape, and effectively reduce the bulk density of the copper powder.

1‧‧‧furnace

2‧‧‧ molten copper

3‧‧‧ leaking holes

4‧‧‧Conical nozzle

5‧‧‧ nozzle

6‧‧‧ copper powder

7‧‧‧ storage bin

11‧‧‧ Missing package

A‧‧‧ copper particles

B‧‧‧ crack

20‧‧‧heat pipe

21‧‧‧heating body

22‧‧‧ lumen

23‧‧‧ inner surface

24‧‧‧ copper powder layer

30‧‧‧All temperature heat sink

31‧‧‧heating body

32‧‧‧ Inside cavity

33‧‧‧ copper powder layer

34‧‧‧Another outer surface of the uniform temperature heat sink

The first figure is a schematic diagram of the manufacturing device of the ultra-low bulk density copper powder according to the creation.

The second figure shows the structure of copper powder prepared by the method of making ultra-low bulk density copper powder.

The third figure shows the surface morphology of the copper particles in the copper powder obtained by the present creation method in the second figure.

The fourth figure shows the structure of the pores or cracks on the surface of the single-particle copper powder in the copper powder under the electron microscope.

The fifth figure is a schematic cross-sectional view of a heat pipe using the copper powder of the present invention.

The sixth figure is a schematic cross-sectional view of a uniform temperature heat sink using the copper powder of the present invention.

As shown in the first to sixth figures, the present invention provides a method for producing ultra-low bulk density copper powder, which is improved on a conventional water atomization method, and can achieve a bulk density of less than 0.8-2.0. The copper powder of g/cm ³ comprises at least the following steps: smelting treatment, atomization treatment, drying treatment, reduction treatment and post treatment.

The smelting treatment is performed at a temperature of 1150 ° C - 1400 ° C (the optimum temperature is 1220 ° C - 1350 ° C), the solid pure copper raw material is melted in the furnace 1, and an aeration operation is performed during the melting, the aeration The operation is to add oxygen to the furnace 1 such that the oxygen content of the molten copper liquid 2 after the aeration is 0.1%-10% (quality percentage), and the optimum value is 0.2%-5%, the aeration operation It is possible to blow oxygen or blow air to the molten metal copper in the furnace 1. The liquid copper melt 2 obtained by the smelting treatment is poured into the leak bag 11 and flows out from the leak hole 3 at the bottom of the leak bag 11, and then enters an atomization treatment process, and the hole diameter of the leak hole 3 is 4 mm to 10 mm (the most Good aperture is 6-8mm).

The atomization treatment is to spray liquid water (usually pure water) to the liquid copper melt 2 by using an atomizing device (the present invention refers to the nozzle 4) when the liquid copper melt 2 flows out of the furnace 1, so that the liquid copper is melted. Liquid 2 is rapidly cooled into granular copper powder 6. The spray head is a conical spray head 4 and is disposed below the furnace leak hole 3, as shown in the first figure, the spray head 4 is composed of 4 to 45 nozzles 5 arranged in a circular shape (the optimal number is 12 to 40), the number of nozzles 5 in the first figure is only illustrative, each of the nozzles 5 is sprayed toward the same injection point A located below the center of the circle, and the nozzles 5 The ejection apex angle (i.e., the angle between the ejection direction M and the vertical direction) is 30 degrees to 55 degrees, thus constituting the tapered nozzle 4. The diameter of the nozzle 5 is 1.0 mm to 4.0 mm (the optimum diameter is 2.0 mm to 3.0 mm), the water pressure in the nozzle 5 is 2 MPa to 10 MPa, and the liquid copper melt 2 flows out from the leak hole 3 The liquid copper melt 2 can be rapidly cooled to form the copper powder 6 under the action of the conical spray head 4 in the vertical direction, and is contained in the storage tub 7.

The drying treatment is to dry and dry the copper powder 6 obtained by the atomization treatment. Including normal temperature centrifuge dehydration drying or heat treatment, the two methods can be carried out separately or in combination, and the heating temperature in the heat treatment is between 100 ° C and 400 ° C.

The reduction treatment is to reduce the copper powder after the drying treatment by using a reducing gas, wherein the reducing gas comprises a hydrogen or a mixed gas of nitrogen and hydrogen, and the temperature of the reduction treatment is between 200 ° C and 800 ° C, wherein the optimal temperature is Between 300 ° C and 600 ° C.

The post-treatment includes crushing, anti-oxidation and sieving of the copper powder to obtain a finished copper powder having a bulk density of 0.8-2.0 g/cm ³ , wherein the anti-oxidation operation uses the antioxidant component C, H, O, N, Cl, F and Si are contained in an amount of 0.001 to 0.2% by mass.

The present invention changes the fluidity and surface tension of the molten metal by using the above smelting process, especially the aerobic operation process, and melts oxygen into the inside of the copper melt, thereby increasing the viscosity of the metal liquid, and better. The spheroidization process of the metal copper droplets during cooling and solidification is resisted, and at the same time, during the atomization treatment, the parameter setting of the cone nozzle 4 can effectively utilize the impact performance of the atomized water, and the optimal metal liquid can be obtained. The cooling rate is decreased, so that the copper particles A constituting the copper powder have a variable and irregular shape (only less than 10% of spherical or spheroidal powder exists), which can be effectively reduced as shown in the second figure. The bulk density of copper powder. In addition, the reduction treatment described in the present invention can effectively remove oxygen contained in the copper powder, so that hydrogen in the reducing gas combines with oxygen in the copper powder to form water and is evaporated at a high temperature, and evaporation of the water causes the copper particles A to Holes or cracks B are formed on the surface, as shown in the third figure.

Compared with the prior art, the manufacturing method described in the present invention can produce copper powder having a bulk density of between 0.8 and 2.0 g/cm ³ , and the copper powder is composed of single-particle copper powder A, since at 1220 The copper melt is rapidly cooled at an optimum temperature of °C-1350 °C, so that there is no or only a small number of agglomeration between the copper powder particles in the copper powder, and the fineness of the copper powder is 18 mesh to 500. Between the eyes, the surface of the single-particle copper powder A in the copper powder is rough and not smooth, and there are holes or cracks B formed by evaporation of water, please refer to the fourth figure. The pores and cracks B are generated during the above-mentioned reduction process. Due to the oxygenation operation during the smelting, a large amount of oxygen is dissolved in the copper liquid, and in the reducing atmosphere, the hydrogen atoms enter the copper powder due to the extremely small atomic radius thereof. Reacts with oxygen to form water vapor, which escapes from the inside of the copper powder, thereby forming a large number of cracks and pores on the surface of the copper powder particles. In addition, after the copper powder obtained by the creation is sintered by vibrating, the porosity is more than 63%, wherein the tapping density of the copper powder after tapping is 1.2-2.5 g/cm ³ , the sintering temperature is 980 ° C, and the sintering time is 30. Minutes, the so-called tap density is a comprehensive manifestation of various physical properties of the powder. It refers to the density (ie the mass per unit volume) of the powder contained in the container under the specified conditions (according to GB5162). In other words, the tap density is related to the bulk density, the particle morphology, the fineness distribution, etc. The copper powder described in the present invention is mainly composed of single-particle copper powder, and the shape of the single-particle copper powder is extremely irregular, thus The porosity between the copper powder particles is relatively high.

The copper powder having a bulk density of between 0.8 and 2.0 g/cm ³ as described in the present invention can be widely used in various fields due to its high porosity (greater than 63%) and irregular shape of single-particle copper powder. Therefore, the gap between the single-particle copper powder is larger and the number of voids is larger, and the copper powder is composed of single-particle copper powder, and there is no or a small number of agglomeration between the copper powder particles, and the foregoing structural characteristics determine The copper powder described in the present invention can be widely used in the field of heat dissipation, such as a CPU for a CPU or a heat sink for a VGA card, because the microstructure of the copper powder can make the heat medium such as air and cooling water well. Through the pores, the heat dissipation performance is good, and the heat dissipation effect of the heat sink can be effectively improved, as exemplified below.

The fifth figure shows a cross-sectional view of a heat pipe for a CPU or a VGA card. The heat sink body 21 of the heat pipe 20 is made of a metal material and has a circular tubular shape and a circular inner cavity 22. The inner cavity 22 is provided with an inner surface 23 and a copper powder layer 24 covering the inner surface 23. The copper powder layer 24 has a thickness of 0.2 mm to 10 mm, and the copper powder layer utilizes the looseness obtained by the creation. The copper powder with a density between 0.8-2.0 g/cm ³ has a higher bulk density and a change in the shape of the copper powder particles, which increases the surface area of the copper powder particles, and the higher porosity thereof also increases. The rate allows air or a cooling medium (such as cooling water) to pass very easily, which greatly improves the heat dissipation efficiency of the heat pipe. Compared with the copper powder in the prior art, the heat pipe of the copper powder of the present invention can greatly improve the heat dissipation. effect.

In addition, in addition to the heat dissipation tube, the VGA graphics card further has a vapor chamber (also referred to as a cavity soaking plate) 30, which is provided with a flat plate and is disposed above the wafer (not shown). The main body 31 is made of a metal material and is provided with an inner cavity 32. The inner surface of the inner cavity 32 is covered with a copper powder layer 33. The copper powder layer 33 is made of copper powder according to the present invention. The powder layer 33 contains a large amount of single-particle copper powder (the spherical copper powder particles in the sixth figure are only schematic, the copper powder particles described in the present invention are actually irregular shapes), and have more than 63% after tapping and sintering. The porosity allows the air or cooling water in the inner cavity 32 to smoothly flow through the gap between the copper powder particles, and the ring cooling is well performed in the inner cavity, thereby greatly improving the heat dissipation of the inner cavity surface of the heat dissipation body 31. Performance, heat can be transferred to the other outer surface 34 of the uniform temperature heat dissipation plate through the heat dissipation body 31, thereby improving the heat dissipation effect of the temperature uniform heat dissipation plate.

The above description is only the preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can use the method disclosed above to solve the technical solution of the present invention without departing from the scope of the present technical solution. Many possible variations and modifications are possible within the scope of the patent scope of the application.

1‧‧‧furnace

2‧‧‧ molten copper

3‧‧‧ leaking holes

4‧‧‧Conical nozzle

5‧‧‧ nozzle

6‧‧‧ copper powder

7‧‧‧ storage bin

11‧‧‧ Missing package

Claims (6)

a copper powder having a bulk density of 0.8 g/cm ³ to 2.0 g/cm ³ and mainly composed of a non-dendritic irregular single-grained copper powder having a rough surface and having pores or The crack, wherein the copper powder has a tap density of 1.2-2.5 g/cm ³ , which is vibrated and has a porosity of more than 63% after sintering at 980 ° C for 30 minutes. The copper powder according to claim 1, wherein the copper powder has a fineness of 18 mesh to 500 mesh. A heat dissipating member comprising a heat dissipating body of a metal material; a copper powder layer covering the heat dissipating body, wherein the copper powder layer has a thickness of 0.2 mm to 10 mm, and the copper powder layer has a bulk density of 0.8 g/cm ³ to 2.0 g/cm ³ of copper powder, and the copper powder is mainly composed of irregularly shaped single-particle copper powder having a tap density of 1.2-2.5 g/cm ³ , which is vibrated and sintered at 980 ° C. The porosity after 30 minutes is greater than 63%. The heat sink according to claim 3, wherein the copper powder has a fineness of 18 mesh to 500 mesh. The heat dissipating member according to claim 3 or 4, wherein the heat dissipating body has a circular tubular shape and is provided with an inner cavity, the inner cavity is provided with an inner surface, and the copper powder layer is disposed on the inner surface on. The heat dissipating member according to claim 5, wherein the heat dissipating body has a flat shape.