Method for plating tungsten and copper on surface of diamond

Abstract

The invention relates to a method for plating tungsten and copper on the surface of diamond, and belongs to the technical field of material surface metallization. The method comprises the following steps: firstly, plating tungsten by adopting a salt bath method: flatly laying auxiliary materials above raw materials, carrying out vacuum sintering for salt bath treatment, cleaning and drying to obtain diamond powder with the surface plated with tungsten; chemical surface modification treatment is conducted firstly, and then chemical copper plating is achieved through a replacement reaction; according to the method, a salt bath process is combined with a chemical plating process, the phenomenon that the thickness of a plating layer is not uniform can be solved, and a product prepared through the method is uniform in plating layer thickness and good in phase consistency of the plating layer; the obtained diamond particles and the surface coating have excellent bonding performance, the interface thermal resistance of the diamond particles is effectively reduced, meanwhile, the compactness of the diamond / copper composite material prepared through a subsequent powder metallurgy method is improved, and the heat dissipation performance of the diamond / copper composite material is improved.

Description

Technical Field

[0001] The present invention relates to a method for plating tungsten copper on the surface of diamond, belonging to the technical field of material surface metallization. Background Art

[0002] With the increasing heat dissipation requirements of the second-generation and third-generation high-power semiconductor chips and devices such as gallium arsenide (GaAs), gallium nitride (GaN), and silicon carbide (SiC), existing packaging materials, such as tungsten copper (WCu) and molybdenum copper (MoCu), can no longer meet the requirements and there is a trend of being phased out by the market. In order to meet the market demand, developing heat dissipation materials with high thermal conductivity and low coefficient of thermal expansion has become the key direction in the current heat dissipation field.

[0003] As a new-generation electronic packaging material, diamond / copper composite material has both the high thermal conductivity of diamond and the designability of the coefficient of thermal expansion of the composite material. Therefore, diamond / copper composite material has become the preferred material for heat dissipation of the second-generation and third-generation high-power semiconductor chips and devices. However, due to the poor wettability between diamond and copper phases, developing or optimizing feasible interface optimization methods has become the core of related research work.

[0004] Currently, there are many process methods for preparing diamond surface coatings, including vacuum evaporation plating method, chemical plating method, salt bath plating method, and thermal diffusion method, etc. Among them, the vacuum evaporation plating method is a coating technology that heats and evaporates the target substance under vacuum conditions and then forms a coating through sublimation and deposition; this method has the advantages of high coating purity, uniform thickness, and wide applicability, and at the same time, the disadvantages of this method are also obvious, mainly including high equipment cost, difficult maintenance, slow evaporation plating speed, and low production efficiency, etc. The chemical plating method is a method for preparing thin films through chemical redox reactions; the advantages of this method are simple process, good bonding strength between the coating and the substrate, high yield, low cost, and recyclable solution, etc., and the disadvantages are mainly that materials with thick coatings cannot be prepared. The salt bath plating method is a method that mixes salts, plating elements, and substrate elements with each other and obtains a coating under certain conditions by using high viscosity and capillary force; this method is simple to operate and does not require special equipment, but has high requirements for controlling process parameters and is extremely easy to coat unevenly. The thermal diffusion method is mainly a method that enables atoms to diffuse with each other at high temperature to form compounds; this method has the advantages of uniform coating thickness and high repeatability, etc., but because the principle adopted by this method is the atomic diffusion principle, it is very difficult to control the phase of the formed coating, and the required reaction temperature and vacuum degree are relatively high.

[0005] The purpose of diamond surface coating is mainly to make the bonding performance between diamond and copper better by introducing intermediate phase elements. Plating a metal on the surface of diamond can only solve one of the problems of tight bonding between diamond and coating, or improving the wettability of copper and coated diamond during the subsequent pressing of finished products, but cannot achieve the effect of taking both into account. However, by plating the tungsten copper layer on the surface of diamond, it is possible to obtain a tungsten carbide layer with high thermal conductivity and stable shape on the surface of diamond, and to achieve good wettability between diamond and copper, thus achieving the optimal performance requirements.

[0006] However, the existing diffusion method is used to plate a tungsten layer on the surface of diamond, and the chemical plating method is used to plate a copper layer. This method is limited by the conditions of the preparation process. The surface coating phase composition of the material prepared by the diffusion method is inconsistent, and there are many impurities on the surface of the material. It is difficult to achieve a uniform coating phase when forming a composite tungsten-copper layer; the existing salt bath method is used to plate tungsten on the surface of diamond. The thickness of the prepared surface tungsten layer is uneven, which will cause the copper plating thickness formed after the chemical copper plating to be inconsistent, affecting the overall quality of the diamond / copper composite material. Summary of the invention

[0007] In order to overcome the defects in the prior art, the purpose of the present invention is to provide a method for plating tungsten copper on the surface of diamond. The product prepared by the method has uniform coating thickness and good phase consistency.

[0008] To achieve the purpose of the present invention, the following technical solutions are provided.

[0009] A method for plating tungsten copper on a diamond surface, the method steps are as follows:

[0010] Step 1: Salt bath tungsten plating

[0011] The auxiliary material is spread on the raw material, vacuum sintered, salt bath treated, cleaned, and dried to obtain diamond powder with tungsten coated on the surface;

[0012] The raw materials are uniformly mixed diamond powder, tungsten powder and tungsten trioxide powder, and the mass ratio of the diamond powder, tungsten powder and tungsten trioxide powder is 1:3-6:3-6.

[0013] Preferably, the particle size of the diamond powder is 15 μm to 200 μm, the particle size of the tungsten powder is 50 μm to 300 μm, and the particle size of the tungsten trioxide powder is 50 μm to 300 μm.

[0014] The auxiliary material is an auxiliary salt commonly used in the salt bath method in the art. Preferably, the auxiliary material is a mixture of sodium chloride and potassium chloride, and the mass ratio of sodium chloride to potassium chloride is 1:1-1.2; or preferably, the auxiliary material is a mixture of sodium chloride and barium chloride, and the mass ratio of sodium chloride to barium chloride is 1:1-1.2.

[0015] The mass ratio of raw materials to auxiliary materials is 3 to 7:1.

[0016] The vacuum sintering is specifically as follows:

[0017] Vacuum is pumped. When the vacuum degree reaches 8.0×10 -3 Pa - 1.0×10 -2 Pa, heating is started. When the temperature reaches 270°C - 330°C, it is kept at a constant temperature for 40 min - 80 min, and then heating continues. When the temperature reaches 930°C - 1030°C, it is kept at a constant temperature for 60 min - 150 min, and then cooled with the furnace to obtain diamond with tungsten plating on the surface.

[0018] The cleaning is specifically as follows:

[0019] First, ultrasonic cleaning is performed with water, then ultrasonic cleaning is performed with organic solution A, then cleaning is performed with water, and finally cleaning is performed with organic solution B.

[0020] Organic solution A is a degreasing solvent, preferably acetone.

[0021] Organic solution B is a dehydrating solvent, preferably absolute ethanol.

[0022] The preferred ultrasonic cleaning is specifically as follows:

[0023] Ultrasonic cleaning with water: The ultrasonic frequency is 15 kHz - 40 kHz, the ultrasonic power is 120 W, and the cleaning time is 10 min - 30 min;

[0024] Ultrasonic cleaning with organic solution A: The ultrasonic frequency is 15 kHz - 40 kHz, the ultrasonic power is 120 W, the ultrasonic cleaning temperature is 30°C - 50°C, and the cleaning time is 20 min - 60 min.

[0025] Sieving can be performed according to the required powder particle size before cleaning. It is preferably sieved using a 50 - mesh to 200 - mesh sieve; a vibrating funnel sieve machine can be used for multiple sieving.

[0026] Since the diamond powder needs to be clean and dry on the surface, and the purchased diamond powder usually has dirt on the surface, the following method can be used to obtain clean and dry diamond powder on the surface:

[0027] The diamond powder is first cleaned with acid, then cleaned with water, then ultrasonically cleaned with organic solution A, the ultrasonically cleaned diamond powder is taken out, cleaned with water, then cleaned with organic solution B, and then dried to obtain clean and dry diamond powder on the surface.

[0028] Preferably, the acid is dilute sulfuric acid or dilute hydrochloric acid; more preferably, the acid is dilute sulfuric acid with a mass fraction of 2% - 10%.

[0029] Organic solution A is a degreasing solvent, preferably acetone.

[0030] The organic solution B is a dehydrating solvent, preferably absolute ethanol.

[0031] Preferably, the diamond powder is put into an acid, stirred and soaked for 30 min to 60 min for cleaning.

[0032] Preferably, the ultrasonic cleaning of the organic solution A is specifically as follows:

[0033] The ultrasonic frequency is 15 kHz to 40 kHz, the ultrasonic power is 120 W, the ultrasonic cleaning temperature is 30 °C to 50 °C, and the cleaning time is 20 min to 60 min.

[0034] Preferably, vacuum drying is carried out at 48 °C to 52 °C for 8 h to 12 h.

[0035] Furthermore, the specific operation of step one is as follows:

[0036] The raw materials are spread on the bottom of an open sintering container, the auxiliary materials are laid flat above the raw materials to cover the opening of the sintering container, and the sintering container containing the raw materials and the auxiliary materials is put into a vacuum sintering furnace for vacuum sintering for salt bath treatment, cleaning, and drying to obtain diamond powder with a tungsten coating on the surface.

[0037] The sintering container adopts a sintering container commonly used in the art, such as a ceramic crucible.

[0038] Since air flow will be generated during vacuum pumping in vacuum sintering, in order to prevent the air flow from carrying away the powdery raw materials and auxiliary materials and causing losses, it is necessary to cover the opening of the sintering container, for example, cover it with a cover plate.

[0039] Step two: Electroless copper plating

[0040] First, chemical surface modification treatment is carried out, and then displacement reaction is carried out to achieve electroless copper plating, specifically as follows:

[0041] (1) Chemical surface modification treatment:

[0042] ① Sensitization treatment

[0043] The diamond powder with a tungsten coating on the surface obtained in step one is put into a sensitizing solution, stirred for sensitization, left standing, and the powder is taken out for cleaning to obtain the sensitized powder.

[0044] The sensitizing solution is a stannous chloride sensitizing solution, which is prepared by mixing stannous chloride, hydrochloric acid solution and water; preferably, the formulation of the stannous chloride sensitizing solution is: 20 g to 40 g of stannous chloride and 40 ml to 80 ml of hydrochloric acid solution with a mass fraction of 37% are contained in each liter of water.

[0045] Preferably, the stirring time for sensitization is 5 min to 15 min.

[0046] Cleaning is a conventional cleaning method after sensitization treatment for preparing diamond surface coatings in this field, such as water washing.

[0047] ②Activation treatment

[0048] Put the sensitized powder into the activation solution, stir and activate it, let it stand, take out the powder and clean it to obtain the activated powder.

[0049] The activation solution is a palladium chloride solution. Preferably, the concentration of palladium chloride in the palladium chloride solution is 0.2 g / l to 0.5 g / l.

[0050] Preferably, the stirring and activation time is 5 min to 10 min.

[0051] Cleaning is a conventional cleaning method after activation treatment for preparing diamond surface coatings in this field, such as water washing.

[0052] (2) Displacement reaction

[0053] Put the activated powder into the plating solution, heat and stir the plating solution: the temperature of the plating solution is 43°C to 45°C, and the pH value of the plating solution is 12.5 to 13.5; when the color of the plating solution becomes colorless, stop heating and stirring, let it stand, then take out the powder, clean it, dry it, and obtain diamond with tungsten copper surface plating, and store it sealed.

[0054] Preferably, the plating solution formula is:

[0055] 13 g to 17 g of copper sulfate pentahydrate, 10 g to 18 g of formaldehyde, 12 g to 18 g of potassium sodium tartrate, 10 g to 15 g of ethylenediaminetetraacetic acid (EDTA), and 0.01 g to 0.03 g of potassium ferrocyanide trihydrate are added to 1 liter of water and mixed.

[0056] Preferably, a magnetic stirrer is used to heat and stir the plating solution, and the stirring speed is 20 revolutions per minute to 80 revolutions per minute.

[0057] Cleaning is a conventional cleaning and drying method after preparing diamond surface chemical coatings in this field. Specifically, it can be carried out in the following way:

[0058] First wash with water, then wash with absolute ethanol, and then dry in vacuum.

[0059] Preferably, the vacuum drying temperature is 48°C to 52°C, and the time is 8 h to 12 h.

[0060] In the present invention, preferably, the water is water with a purity higher than that of deionized water.

[0061] Beneficial effects

[0062] (1) The present invention provides a method for plating tungsten copper on the surface of diamond. The salt bath process provided in the method of the present invention is combined with a chemical plating process to solve the problem of uneven coating thickness. The product prepared by the method has a uniform coating thickness and good consistency of the coating.

[0063] (2) The present invention provides a method for plating tungsten and copper on the surface of diamond. The diamond particles obtained by the method of the present invention have excellent bonding properties with the surface coating, effectively reducing the thermal resistance of the diamond particle interface, while improving the density of the subsequent powder metallurgy method to prepare the diamond / copper composite material, thereby improving the heat dissipation performance of the diamond / copper composite material.

[0064] (3) The present invention provides a method for plating tungsten copper on the surface of diamond. In the method, when tungsten is plated on the surface of diamond by a salt bath method, tungsten powder and tungsten trioxide powder are selected as raw materials mainly because the reaction of tungsten and diamond to form tungsten carbide is a complicated process. Since the tungsten in tungsten trioxide has a high valence and high activity, adding a certain proportion of tungsten trioxide to tungsten powder makes it easier for tungsten to react with diamond to form tungsten carbide on the surface.

[0065] (4) The present invention provides a method for plating tungsten copper on a diamond surface. In the method, the mass ratio of raw materials diamond powder, tungsten powder and tungsten trioxide powder is designed to be 1:3-6:3-6, which can ensure that the diamond is not carbonized and the plating reaction is more complete and the thickness is more uniform; it can reduce the residue remaining on the diamond surface after the salt bath, shorten the reaction time in the furnace, and improve production efficiency.

[0066] (5) The present invention provides a method for plating tungsten copper on the surface of diamond. In the method, since airflow is generated during vacuum sintering, in order to prevent the airflow from carrying away powdered raw materials and auxiliary materials and causing losses, the opening of the sintering container needs to be covered.

[0067] (6) The present invention provides a method for plating tungsten copper on the surface of diamond. In the method, a sensitizing solution containing 20g to 40g of stannous chloride and 40ml to 80ml of a 37% hydrochloric acid solution per liter of water is used, which is more conducive to a sufficient sensitization reaction, improves the activity of the surface of the diamond particles, and is conducive to improving the bonding of the copper layer on the surface of the diamond particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a scanning electron microscope (SEM) image of the diamond powder with tungsten coated on the surface obtained in step 1 of Example 1.

[0069] Figure 2 This is a SEM image of the diamond with tungsten-copper coating on the surface obtained in step 2 of Example 1. DETAILED DESCRIPTION

[0070] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but it is not intended to limit the patent of the present invention.

[0071] A method for plating tungsten copper on the surface of diamond, the steps of the method are as follows:

[0072] Step 1: Plating tungsten by salt bath method

[0073] (1) Put the commercially available diamond powder into dilute sulfuric acid with a mass fraction of 2% - 10%, stir and soak for 30 min - 60 min, then wash with distilled water, and then put it into acetone for ultrasonic cleaning. The ultrasonic frequency is 15 kHz - 40 kHz, the ultrasonic power is 120 W, the ultrasonic cleaning temperature is 30°C - 50°C, and the cleaning time is 20 min - 60 min; take out the diamond powder after ultrasonic cleaning, wash it with distilled water, then put it into absolute ethanol for cleaning, and then put it into a vacuum drying oven for drying treatment. The drying temperature is 48°C - 52°C, and the drying time is 8 h - 12 h to obtain diamond powder with a clean and dry surface.

[0074] (2) The raw materials: diamond powder, tungsten powder and tungsten trioxide powder are proportioned according to a mass ratio of 1:3 - 6:3 - 6. The particle size of the diamond powder is 15 μm - 200 μm, the particle size of the tungsten powder is 50 μm - 300 μm, and the particle size of the tungsten trioxide powder is 50 μm - 300 μm; put the proportioned raw materials into a powder mixer for mixing for 2 h - 5 h to obtain uniformly mixed raw materials; the auxiliary materials are a mixture of sodium chloride and potassium chloride, and the mass ratio of sodium chloride to potassium chloride is 1:1 - 1.2, or the auxiliary materials are a mixture of sodium chloride and barium chloride, and the mass ratio of sodium chloride to barium chloride is 1:1 - 1.2;

[0075] Put the uniformly mixed raw materials at the bottom of a ceramic crucible, and then spread the uniformly mixed auxiliary materials on top of the raw materials. The mass ratio of the raw materials to the auxiliary materials is 3 - 7:1; then cover the top opening of the ceramic crucible with a cover plate;

[0076] Put the ceramic crucible filled with raw materials and auxiliary materials into a vacuum sintering furnace for vacuum sintering for salt bath treatment: evacuate, when the vacuum degree reaches 8.0×10 -3 Pa - 1.0×10 -2 Pa, start heating. When the temperature reaches 270°C - 330°C, keep the temperature constant for 40 min - 80 min, and then continue to heat. When the temperature reaches 930°C - 1030°C, keep the temperature constant for 60 min - 150 min, turn off the heating power, and cool down with the furnace to obtain diamond powder with tungsten plated on the surface.

[0077] (3) Use a vibrating funnel sieve machine to screen the diamond powder with tungsten plated on the surface multiple times with a 50 - mesh to 200 - mesh sieve to obtain diamond powder with tungsten plated on the surface with the required particle size.

[0078] (4) The diamond powder with tungsten coating on its surface screened out in step (3) is ultrasonically cleaned with deionized water for 10 min to 30 min, the ultrasonic frequency is 15 kHz to 40 kHz, the ultrasonic power is 120 W. After taking it out, it is ultrasonically cleaned in acetone for 20 min to 60 min, the ultrasonic frequency is 15 kHz to 40 kHz, the ultrasonic power is 120 W, and the ultrasonic cleaning temperature is 30 °C to 50 °C; take out the powder after ultrasonic cleaning, wash it with distilled water, and then put it into absolute ethanol for cleaning and take it out; after drying, clean diamond powder with tungsten coating on its surface is obtained.

[0079] Step Two: Electroless Copper Plating

[0080] First, perform chemical surface modification treatment, and then carry out displacement reaction to achieve electroless copper plating, specifically as follows:

[0081] (1) Chemical surface modification treatment:

[0082] ① Sensitization treatment

[0083] Put the diamond powder with tungsten coating on its surface prepared in step one into the sensitizing solution, stir sensitize it with magnetic stirring for 5 min to 15 min, let it stand, take out the powder, and wash it with distilled water to obtain the sensitized powder;

[0084] The sensitizing solution is stannous chloride sensitizing solution, which is prepared by mixing stannous chloride, hydrochloric acid solution and water; the specific formula of the stannous chloride sensitizing solution is: 20 g to 40 g of stannous chloride and 40 ml to 80 ml of hydrochloric acid solution with a mass fraction of 37% are contained in each liter of water.

[0085] ② Activation treatment

[0086] Put the sensitized powder into the activation solution, stir and activate it with magnetic stirring for 5 min to 10 min, let it stand, take out the powder, and wash it with distilled water to obtain the activated powder;

[0087] The activation solution is palladium chloride solution with a palladium chloride concentration of 0.2 g / l to 0.4 g / l.

[0088] (2) Displacement reaction

[0089] Put the activated powder into the plating solution, heat and stir the plating solution with a magnetic stirrer: the stirring speed is 20 revolutions per minute to 80 revolutions per minute, the temperature of the plating solution is 43 °C to 45 °C, and the pH value of the plating solution is 12.5 to 13.5; when the color of the plating solution becomes colorless, stop stirring and heating, let it stand, then take out the powder, wash the powder with distilled water, then put the powder into absolute ethanol for cleaning, and then put it into a vacuum drying oven for drying treatment, the drying temperature is 48 °C to 52 °C, and the time is 8 h to 12 h, to obtain diamond with tungsten - copper coating on its surface, take it out and store it sealed.

[0090] The plating solution formula is as follows:

[0091] Mix 13 g - 17 g of copper sulfate pentahydrate, 10 g - 18 g of formaldehyde, 12 g - 18 g of potassium sodium tartrate, 10 g - 15 g of ethylenediaminetetraacetic acid (EDTA), 0.01 g - 0.03 g of potassium ferrocyanide trihydrate with 1 liter of deionized water to prepare the plating solution.

[0092] Example 1

[0093] A method for plating tungsten - copper on the surface of diamond, the steps of the method are as follows:

[0094] Step 1: Plating tungsten by salt - bath method

[0095] (1) Put 20 g of commercially available diamond powder into dilute sulfuric acid with a mass fraction of 2% and stir and soak for 60 min; then wash it 5 times with distilled water; then put it into acetone for ultrasonic cleaning, the ultrasonic frequency is 15 kHz, the ultrasonic power is 120 W, the ultrasonic cleaning temperature is 50 °C, and the ultrasonic cleaning time is 60 min; take out the ultrasonically cleaned diamond powder, wash it 5 times with distilled water, then wash it 2 times with absolute ethanol, and then put it into a vacuum drying oven for drying treatment, the drying temperature is controlled at 48 °C, and the drying time is 8 h to obtain clean and dry diamond powder on the surface.

[0096] (2) Weigh the raw materials: 10 g of clean and dry diamond powder on the surface, 30 g of tungsten powder and 30 g of tungsten trioxide, the particle size of the diamond powder is 15 μm, the particle size of the tungsten powder is 100 μm, and the particle size of the tungsten trioxide powder is 100 μm; mix the three raw materials and put them into a powder mixer for 2 h of mixing to obtain uniformly mixed raw materials; weigh 5 g of sodium chloride and 5 g of potassium chloride, and mix them well as auxiliary materials;

[0097] Put the uniformly mixed raw materials at the bottom of a ceramic crucible, then spread the uniformly mixed auxiliary materials on top of the raw materials, and the mass ratio of the raw materials to the auxiliary materials is 7:1; then cover the top opening of the ceramic crucible with a cover plate;

[0098] Put the ceramic crucible filled with raw materials and auxiliary materials into a vacuum sintering furnace to evacuate, when the vacuum degree reaches 8.0×10 - 3 Pa, start heating, when the temperature reaches 300 °C, keep it at a constant temperature for 60 min, then continue heating, when the temperature reaches 980 °C, keep it at a constant temperature for 80 min, turn off the heating power, and cool down with the furnace to obtain diamond powder with tungsten plated on the surface.

[0099] (3) Use a vibrating funnel sieve machine to sieve the diamond powder with tungsten plated on the surface 4 times with a 200 - mesh sieve to obtain diamond powder with tungsten plated on the surface with a particle size of 15 μm.

[0100] (4) The diamond powder with tungsten plating on the surface screened out in step (3) is ultrasonically cleaned with deionized water for 10 min, the ultrasonic frequency is 15 kHz, and the ultrasonic power is 120 W. After taking it out, it is put into acetone and ultrasonically cleaned for 20 min, the ultrasonic frequency is 15 kHz, and the ultrasonic power is 120 W. The ultrasonic cleaning temperature is 30 °C; the powder after ultrasonic cleaning is taken out, washed 3 times with distilled water, then put into absolute ethanol and washed 2 times and then taken out; after drying, the clean diamond powder with tungsten plating on the surface is obtained.

[0101] Step Two: Electroless Copper Plating

[0102] First, perform chemical surface modification treatment, and then carry out displacement reaction to achieve electroless copper plating, specifically as follows:

[0103] (1) Chemical surface modification treatment:

[0104] ① Sensitization treatment

[0105] Put the diamond powder with tungsten plating on the surface prepared in step one into the sensitizing solution, stir sensitize it with magnetic stirring for 5 min, let it stand, take out the powder, and wash it 3 times with distilled water to obtain the sensitized powder;

[0106] The sensitizing solution is stannous chloride sensitizing solution, and the specific formula is as follows:

[0107] Prepare the sensitizing solution by mixing stannous chloride, hydrochloric acid with a mass fraction of 37% and deionized water. There are 35 g of stannous chloride and 50 ml of hydrochloric acid with a mass fraction of 37% in each liter of deionized water.

[0108] ② Activation treatment

[0109] Put the sensitized powder into the activation solution, stir and activate it with magnetic stirring for 10 min, let it stand, take out the powder, and wash it 3 times with distilled water to obtain the activated powder;

[0110] The activation solution is a palladium chloride solution with a concentration of 0.2 g / l.

[0111] (2) Displacement reaction

[0112] Put the activated powder into the plating solution, heat and stir the plating solution with a magnetic stirrer: the stirring speed is 40 revolutions per minute, the temperature of the plating solution is 45 °C, and the pH value of the plating solution is 12.5; when the color of the plating solution becomes colorless, stop heating and stirring, let it stand, then take out the powder, wash the powder 3 times with distilled water, then put the powder into absolute ethanol and wash it 2 times, and then put it into a vacuum drying oven for drying treatment, the drying temperature is 50 °C, and the time is 8 h, to obtain diamond with tungsten - copper plating on the surface, and store it sealed.

[0113] The plating solution formula is as follows:

[0114] Copper sulfate pentahydrate, formaldehyde, sodium potassium tartrate, ethylenediaminetetraacetic acid (EDTA), and potassium ferrocyanide trihydrate are mixed with deionized water to prepare a plating solution. There are 13 g of copper sulfate pentahydrate, 10 g of formaldehyde, 12 g of sodium potassium tartrate, 10 g of ethylenediaminetetraacetic acid, and 0.01 g of potassium ferrocyanide trihydrate in each liter of deionized water.

[0115] The diamond powder with tungsten plating on the surface prepared in Step 1 of this embodiment and the diamond with tungsten - copper plating on the surface prepared in Step 2 are tested and observed as follows:

[0116] The diamond powder with tungsten plating on the surface prepared in Step 1 of this embodiment is observed by a scanning electron microscope (SEM), as Figure 1 shown. Figure 1 In [figure], the bright - white part on the diamond surface is the morphology of tungsten plating on the diamond surface, and the bright spots on the material surface are impurities. It can be seen from the figure that the tungsten layer uniformly covers the diamond surface, and there is no large - area non - plating phenomenon, indicating that this process can ensure that the diamond is not carbonized, the plating reaction is more sufficient, and the thickness is more uniform.

[0117] The diamond with tungsten - copper plating on the surface prepared in Step 2 of this embodiment is observed by a scanning electron microscope, as Figure 2 shown. Figure 2 In [figure], the coating on the surface of the diamond after electroless copper plating has the same color and is smooth on the surface. It is proved that the copper - plating layer of the material is dense and the coating thickness is uniform. There are no impurities on the surface of the coating after cleaning, and the cleanliness is high.

[0118] Example 2

[0119] A method for plating tungsten - copper on the surface of diamond, the steps of the method are as follows:

[0120] Step 1: Tungsten plating by salt - bath method

[0121] (1) Put 20 g of commercially available diamond powder into dilute sulfuric acid with a mass fraction of 10% and stir - soak for 30 min; then wash it 3 times with distilled water; then put it into acetone for ultrasonic cleaning. The ultrasonic frequency is 30 kHz, the ultrasonic power is 120 W, the ultrasonic cleaning temperature is 30 °C, and the ultrasonic cleaning time is 20 min; take out the diamond powder after ultrasonic cleaning, wash it 3 times with distilled water, then wash it 2 times with absolute ethanol, and then put it into a vacuum drying oven for drying treatment. The drying temperature is controlled at 50 °C, and the drying time is 12 h to obtain clean and dry diamond powder.

[0122] (2) Weigh the raw materials: 10 g of diamond powder with a clean and dry surface, 40 g of tungsten powder, and 40 g of tungsten trioxide. The particle size of the diamond powder is 200 μm, the particle size of the tungsten powder is 300 μm, and the particle size of the tungsten trioxide powder is 300 μm. Mix the three raw materials and put them into a powder mixer for 5 h of mixing to obtain uniformly mixed raw materials. Weigh 14 g of sodium chloride and 16 g of potassium chloride, and mix them well as auxiliary materials.

[0123] Put the uniformly mixed raw materials at the bottom of a ceramic crucible, and then spread the uniformly mixed auxiliary materials evenly on top of the raw materials. The mass ratio of the raw materials to the auxiliary materials is 3:1. Then cover the top opening of the ceramic crucible with a cover plate.

[0124] Put the ceramic crucible filled with raw materials and auxiliary materials into a vacuum sintering furnace to evacuate. When the vacuum degree reaches 1.0×10 - 2 Pa, start heating. When the temperature reaches 270 °C, keep it at a constant temperature for 40 min, and then continue heating. When the temperature reaches 930 °C, keep it at a constant temperature for 60 min, turn off the heating power, and cool down with the furnace to obtain diamond powder with a tungsten coating on the surface.

[0125] (3) Use a vibrating funnel sieve machine to screen the diamond powder with a tungsten coating on the surface 3 times with a 150-mesh sieve to obtain diamond powder with a tungsten coating on the surface and a particle size of 200 μm.

[0126] (4) Ultrasonically clean the diamond powder with a tungsten coating on the surface screened in step (3) with deionized water for 20 min. The ultrasonic frequency is 30 kHz, and the ultrasonic power is 120 W. Take it out and put it into acetone for ultrasonic cleaning for 40 min. The ultrasonic frequency is 30 kHz, the ultrasonic power is 120 W, and the ultrasonic cleaning temperature is 40 °C. Take out the powder after ultrasonic cleaning, wash it 3 times with distilled water, and then put it into absolute ethanol for cleaning 2 times and then take it out. After drying, obtain clean diamond powder with a tungsten coating on the surface.

[0127] Step 2: Electroless copper plating

[0128] First, perform chemical surface modification treatment, and then carry out a displacement reaction to achieve electroless copper plating, specifically as follows:

[0129] (1) Chemical surface modification treatment:

[0130] ① Sensitization treatment

[0131] Put the diamond powder with a tungsten coating on the surface prepared in step 1 into the sensitizing solution, stir it magnetically for 15 min for sensitization, let it stand, take out the powder, and wash it 3 times with distilled water to obtain the sensitized powder.

[0132] The sensitizing solution is a stannous chloride sensitizing solution, and the specific formula is as follows:

[0133] Prepare a sensitizing solution by mixing stannous chloride, 37% hydrochloric acid, and deionized water. There are 20 g of stannous chloride and 40 ml of 37% hydrochloric acid in each liter of deionized water.

[0134] ②Activation treatment

[0135] Put the sensitized powder into the activation solution, stir magnetically for 5 min for activation, let it stand, take out the powder, and wash it 3 times with distilled water to obtain the activated powder.

[0136] The activation solution is a palladium chloride solution with a concentration of 0.4 g / l.

[0137] (2) Displacement reaction

[0138] Put the activated powder into the plating solution, heat and stir the plating solution with a magnetic stirrer: the stirring speed is 20 revolutions per minute, the temperature of the plating solution is 43 °C, and the pH value of the plating solution is 13.5; when the color of the plating solution becomes colorless, stop stirring and heating, let it stand, then take out the powder, wash the powder 3 times with distilled water, then put the powder into absolute ethanol and wash it 2 times, and then put it into a vacuum drying oven for drying treatment. The drying temperature is 52 °C and the time is 12 h to obtain diamond coated with tungsten copper on the surface, and store it sealed.

[0139] The plating solution formula is as follows:

[0140] Mix copper sulfate pentahydrate, formaldehyde, sodium potassium tartrate, ethylenediaminetetraacetic acid, and potassium ferrocyanide trihydrate with deionized water to prepare a plating solution. There are 17 g of copper sulfate pentahydrate, 18 g of formaldehyde, 18 g of sodium potassium tartrate, 15 g of ethylenediaminetetraacetic acid, and 0.03 g of potassium ferrocyanide trihydrate in each liter of deionized water.

[0141] Test and observe the diamond powder coated with tungsten on the surface prepared in Step 1 and the diamond coated with tungsten copper on the surface prepared in Step 2 of this example as follows:

[0142] Observe the diamond powder coated with tungsten on the surface prepared in Step 1 of this example using a scanning electron microscope. The result is Figure 1 similar. The result shows that the bright white part on the diamond surface is the morphology of tungsten coating on the diamond surface, and the bright spots on the material surface are impurities. It can be seen from the figure that the tungsten layer uniformly covers the diamond surface, and there is no large-area non-plating phenomenon, indicating that this process can ensure that the plating reaction is more sufficient and the thickness is more uniform under the condition that the diamond is not carbonized.

[0143] Observe the diamond coated with tungsten copper on the surface prepared in Step 2 of this example using a scanning electron microscope. The result is Figure 2Similar. The results show that the coating on the surface of the diamond after electroless copper plating has a consistent color and a smooth surface. It proves that the copper plating layer on the material is dense and the coating thickness is uniform. There are no impurities on the surface of the coating after cleaning, and the cleanliness is high.

[0144] Example 3

[0145] A method for tungsten-copper plating on the surface of diamond, the steps of the method are as follows:

[0146] Step 1: Tungsten plating by salt bath method

[0147] (1) Put 20 g of commercially available diamond powder into dilute sulfuric acid with a mass fraction of 8% and stir and soak for 60 min, then wash it 3 times with distilled water; then put it into acetone for ultrasonic cleaning, the ultrasonic frequency is 40 kHz, the ultrasonic power is 120 W, the ultrasonic cleaning temperature is 45 °C, and the ultrasonic cleaning time is 30 min; take out the diamond powder after ultrasonic cleaning, wash it 3 times with distilled water, then put it into absolute ethanol for cleaning 2 times, and then put it into a vacuum drying oven for drying treatment, the drying temperature is controlled at 52 °C, and the drying time is 8 h to obtain diamond powder with a clean and dry surface.

[0148] (2) Weigh the raw materials: 10 g of diamond powder with a clean and dry surface, 60 g of tungsten powder and 60 g of tungsten trioxide. The particle size of the diamond powder is 100 μm, the particle size of the tungsten powder is 50 μm, and the particle size of the tungsten trioxide powder is 50 μm; mix the three raw materials and put them into a powder mixer for 4 h of mixing to obtain uniformly mixed raw materials; weigh 10 g of sodium chloride and 10 g of potassium chloride and mix them well as auxiliary materials;

[0149] Put the uniformly mixed raw materials at the bottom of a ceramic crucible, then spread the uniformly mixed auxiliary materials on top of the raw materials, and the mass ratio of the raw materials to the auxiliary materials is 5.5:1; then cover the top opening of the ceramic crucible with a cover plate;

[0150] Put the ceramic crucible filled with raw materials and auxiliary materials into a vacuum sintering furnace to evacuate. When the vacuum degree reaches 1.0×10 - 2 Pa, start heating. When the temperature reaches 330 °C, keep it at a constant temperature for 80 min, then continue to heat. When the temperature reaches 1030 °C, keep it at a constant temperature for 150 min, turn off the heating power, and cool down with the furnace to obtain diamond powder with tungsten plated on the surface.

[0151] (3) Use a vibrating funnel sieve machine to sieve the diamond powder with tungsten plated on the surface 3 times with a 100-mesh sieve to obtain diamond powder with tungsten plated on the surface and a particle size of 100 μm.

[0152] (4) Ultrasonically clean the diamond powder with tungsten plating on its surface, which is screened out in step (3), in deionized water for 30 min, with an ultrasonic frequency of 40 kHz and an ultrasonic power of 120 W. After taking it out, ultrasonically clean it in acetone for 60 min, with an ultrasonic frequency of 40 kHz, an ultrasonic power of 120 W, and an ultrasonic cleaning temperature of 50 °C. Take out the powder after ultrasonic cleaning, wash it 3 times with distilled water, then put it into absolute ethanol and wash it 2 times before taking it out; after drying, obtain clean diamond powder with tungsten plating on its surface.

[0153] Step Two: Electroless Copper Plating

[0154] First, conduct chemical surface modification treatment, and then achieve electroless copper plating through displacement reaction, specifically as follows:

[0155] (1) Chemical surface modification treatment:

[0156] ① Sensitization treatment

[0157] Put the diamond powder with tungsten plating on its surface prepared in Step One into the sensitizing solution, stir it magnetically for 15 min for sensitization, let it stand, take out the powder, and wash it 3 times with distilled water to obtain the sensitized powder;

[0158] The sensitizing solution is a stannous chloride sensitizing solution, and the specific formula is as follows:

[0159] Prepare the sensitizing solution by mixing stannous chloride, hydrochloric acid with a mass fraction of 37% and deionized water. There are 40 g of stannous chloride and 80 ml of hydrochloric acid with a mass fraction of 37% in each liter of deionized water.

[0160] ② Activation treatment

[0161] Put the sensitized powder into the activation solution, stir it magnetically for 8 min for activation, let it stand, take out the powder, and wash it 3 times with distilled water to obtain the activated powder;

[0162] The activation solution is a palladium chloride solution with a concentration of 0.4 g / l.

[0163] (2) Displacement reaction

[0164] Put the activated powder into the plating solution, heat and stir the plating solution with a magnetic stirrer: the stirring speed is 80 revolutions per minute, the temperature of the plating solution is 44 °C, and the pH value of the plating solution is 13; when the color of the plating solution becomes colorless, stop stirring and heating, let it stand, then take out the powder, wash the powder 3 times with distilled water, then put the powder into absolute ethanol and wash it 2 times, and then put it into a vacuum drying oven for drying treatment, with a drying temperature of 48 °C and a time of 8 h, to obtain diamond with tungsten and copper plating on its surface, and store it sealed.

[0165] The plating solution formula is as follows:

[0166] Copper sulfate pentahydrate, formaldehyde, sodium potassium tartrate, ethylenediaminetetraacetic acid and potassium ferrocyanide trihydrate are mixed with deionized water to prepare a plating solution. There are 15 g of copper sulfate pentahydrate, 16 g of formaldehyde, 15 g of sodium potassium tartrate, 13 g of ethylenediaminetetraacetic acid and 0.02 g of potassium ferrocyanide trihydrate in each liter of deionized water.

[0167] The diamond powder with a tungsten coating on the surface obtained in Step 1 of the preparation of this example and the diamond with a tungsten - copper coating on the surface obtained in Step 2 are tested and observed as follows:

[0168] The diamond powder with a tungsten coating on the surface obtained in Step 1 of the preparation of this example is observed using a scanning electron microscope. The result is similar to Figure 1 that. The result shows that the bright - white part on the diamond surface is the morphology of the tungsten coating on the diamond surface, and the bright spots on the material surface are impurities. It can be seen from the figure that the tungsten layer uniformly covers the diamond surface, and there is no large - area non - plating phenomenon, indicating that this process can ensure that the diamond is not carbonized, the plating reaction is more sufficient, and the thickness is more uniform.

[0169] The diamond with a tungsten - copper coating on the surface obtained in Step 2 of the preparation of this example is observed using a scanning electron microscope. The result is similar to Figure 2 that. The result shows that the coating on the diamond surface has a consistent color and is smooth after electroless copper plating. It is proved that the copper - plating layer of the material is dense and the coating thickness is uniform. There are no impurities on the surface of the coating after cleaning, and the cleanliness is high.

Claims

1. A method for plating tungsten copper on the surface of diamond, characterized in that: Step 1: Plating tungsten by salt bath method Spread the auxiliary materials on top of the raw materials, conduct salt bath treatment through vacuum sintering, wash, and dry to obtain diamond powder with tungsten plated on the surface; The raw materials are uniformly mixed diamond powder, tungsten powder, and tungsten trioxide powder, and the mass ratio of diamond powder, tungsten powder, and tungsten trioxide powder is 1:3 - 6:3 - 6; The mass ratio of the raw materials to the auxiliary materials is 3 - 7:1; Step 2: Electroless copper plating (1) Chemical surface modification treatment: ① Sensitization treatment Put the diamond powder with tungsten plated on the surface into the sensitizing solution, stir and sensitize, let it stand, take out the powder and wash to obtain the sensitized powder; The sensitizing solution is a stannous chloride sensitizing solution, prepared by mixing stannous chloride, hydrochloric acid solution, and water; ② Activation treatment Put the sensitized powder into the activation solution, stir and activate, let it stand, take out the powder and wash to obtain the activated powder; The activation solution is a palladium chloride solution; (2) Displacement reaction Put the activated powder into the plating solution, heat and stir the plating solution: the temperature of the plating solution is 43°C - 45°C, and the pH value of the plating solution is 12.5 - 13.5; when the color of the plating solution becomes colorless, stop heating and stirring, let it stand, then take out the powder, wash, and dry to obtain diamond with tungsten copper plated on the surface.

2. The method for plating tungsten copper on the surface of diamond according to claim 1, characterized in that: Specifically, Step 1 is: Lay the raw materials at the bottom of an open sintering container, spread the auxiliary materials on top of the raw materials, cover the opening of the sintering container, put the sintering container containing the raw materials and auxiliary materials into a vacuum sintering furnace for vacuum sintering for salt bath treatment, wash, and dry to obtain diamond powder with tungsten plated on the surface.

3. A method for plating tungsten copper on the surface of diamond according to claim 1, characterized in that: In Step 1, the particle size of the diamond powder is 15μm - 200μm, the particle size of the tungsten powder is 50μm - 300μm, and the particle size of the tungsten trioxide powder is 50μm - 300μm; The auxiliary material is a mixture of sodium chloride and potassium chloride, and the mass ratio of sodium chloride to potassium chloride is 1:1 - 1.2; or the auxiliary material is a mixture of sodium chloride and barium chloride, and the mass ratio of sodium chloride to barium chloride is 1:1 - 1.2; In Step 2, the formula of the stannous chloride sensitizing solution is: 20g - 40g of stannous chloride and 40ml - 80ml of hydrochloric acid solution with a mass fraction of 37% are contained in each liter of water; The concentration of palladium chloride in the palladium chloride solution is 0.2g / l - 0.5g / l; The formula of the plating solution is: 13g - 17g of copper sulfate pentahydrate, 10g - 18g of formaldehyde, 12g - 18g of potassium sodium tartrate, 10g - 15g of ethylenediaminetetraacetic acid, and 0.01g - 0.03g of potassium ferrocyanide trihydrate are added to 1 liter of water and mixed and prepared.

4. A method for plating tungsten copper on the surface of diamond according to any one of claims 1 to 3, characterized in that: In Step 1, the vacuum sintering is specifically: Evacuate to a vacuum. When the vacuum degree reaches 8.0×10 -3 Pa to 1.0×10 -2 Pa, start heating up. When the temperature reaches 270°C to 330°C, keep it at a constant temperature for 40 min to 80 min, then continue heating up. When the temperature reaches 930°C to 1030°C, keep it at a constant temperature for 60 min to 150 min, and then cool down with the furnace to obtain diamond with tungsten coating on the surface; In Step 2, the stirring and sensitizing time is 5min - 15min; the stirring and activating time is 5min - 10min; use a magnetic stirrer to heat and stir the plating solution, and the stirring speed is 20 revolutions per minute - 80 revolutions per minute.

5. A method for plating tungsten copper on the surface of diamond according to claim 1, characterized in that: In Step 1, before washing, screen according to the required powder particle size using a 50 - mesh - 200 - mesh sieve.

6. A method for plating tungsten copper on the surface of diamond according to claim 1, characterized in that: In Step 1, the washing is specifically: First, wash ultrasonically with water, then wash ultrasonically with organic solution A, then wash with water, and finally wash with organic solution B; organic solution A is a degreasing solvent, and organic solution B is a dehydrating solvent; In Step 2, the cleaning and drying are specifically as follows: First, wash with water, then wash with absolute ethanol, and then perform vacuum drying. The vacuum drying temperature is 48°C to 52°C, and the time is 8h to 12h.

7. A method for plating tungsten copper on the surface of diamond according to claim 6, characterized in that: Wash with water by ultrasonic wave: The ultrasonic wave frequency is 15kHz to 40kHz, the ultrasonic power is 120W, and the cleaning time is 10min to 30min.

8. A method for plating tungsten copper on the surface of diamond according to claim 1, characterized in that: In Step 1, the following method is adopted to obtain diamond powder with a clean and dry surface: First, wash the diamond powder with acid, then wash with water, then perform ultrasonic cleaning with organic solution A. Take out the diamond powder after ultrasonic cleaning, wash with water, then wash with organic solution B, and then dry to obtain diamond powder with a clean and dry surface; organic solution A is a degreasing solvent, and organic solution B is a water-removing solvent.

9. A method for plating tungsten copper on the surface of diamond according to claim 8, characterized in that: The acid is dilute sulfuric acid or dilute hydrochloric acid; the diamond powder is put into dilute sulfuric acid with a mass fraction of 2% to 10% and stirred and soaked for 30min to 60min for cleaning; vacuum drying is performed at 48°C to 52°C for 8h to 12h.

10. A method for plating tungsten copper on the surface of diamond according to claim 6 or 8, characterized in that: Organic solution A is acetone, and organic solution B is absolute ethanol; Perform ultrasonic cleaning with organic solution A: The ultrasonic wave frequency is 15kHz to 40kHz, the ultrasonic power is 120W, the ultrasonic cleaning temperature is 30°C to 50°C, and the cleaning time is 20min to 60min.

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