A preparation method of gold, platinum and palladium for electronic paste

Abstract

The present invention belongs to the technical field of powder metallurgy, and specifically relates to a method for preparing gold, platinum and palladium for electronic paste. A method for preparing gold, platinum and palladium for electronic paste, the method comprising the following steps: high-energy ball milling of gold powder, platinum powder, palladium powder and aluminum powder to obtain a gold, platinum, palladium and aluminum mixed powder, and then high-temperature alkali dissolution to obtain a gold, platinum and palladium aluminum suspension solution, filtering, washing and drying to obtain a gold, platinum and palladium powder, and annealing in a tubular furnace to finally obtain a gold, platinum and palladium alloy powder. The process of the present invention is simple and stable, the degree of alloying of the powder is high, the gold, platinum and palladium are uniformly spherical, the dispersibility is good, and the particle size is controllable.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a method for preparing gold, platinum and palladium for electronic paste. Background Art

[0002] With the rapid development of modern science and technology, especially electronic information, communication technology, artificial intelligence technology, and high-end technologies such as aerospace, the requirements for multifunctionality, high reliability, and high integration of electronic components are increasing. At present, in the manufacturing technology of electronic products, the use of low-temperature co-fired ceramic technology has become a very important manufacturing technology. The substrate produced by this technology has the functions of realizing IC chip packaging, embedded passive components, and high-density circuit assembly. It can be widely used in various electronic devices, such as various mobile phones, Bluetooth headsets, automotive electronic devices, wireless local area networks, terrestrial digital broadcasting, global positioning system receiver components, digital signal processors and memories, and other power supply components and even digital circuit component substrates. Gold platinum palladium electronic paste has excellent properties, such as solderability and reliability, and can be used as solderability paste in LTCC. The most important component of gold platinum palladium electronic paste is gold platinum palladium alloy powder, so the performance of high-performance gold platinum palladium alloy powder is the guarantee of the characteristics of gold platinum palladium paste. In the preparation process of gold-platinum-palladium slurry, gold-platinum-palladium powder can be used in three forms: mixed powder, coprecipitated powder and alloy powder. Since gold, platinum and palladium in alloy powder are almost evenly distributed at the atomic level, practice has proved that it usually has better performance. However, the gold-platinum-palladium alloy powder currently used in my country is almost all imported and cannot be replaced at present, so it is very important to develop a preparation technology for gold-platinum-palladium alloy powder for electronic slurry.

[0003] The Chinese invention patent application with publication number CN103192090A discloses a liquid phase preparation method for monodisperse spherical gold, platinum and palladium alloy powder. The method is to add corresponding mass of gold, platinum and palladium metal raw materials into a beaker according to the ratio requirements of the three elements of gold, platinum and palladium in the target product, then add aqua regia and heat to dissolve it completely, and dilute the mixed solution containing gold, platinum and palladium with deionized water to a certain concentration as a raw material liquid; a certain amount of reducing agent is added to the solvent for dilution and mixed, and then a surfactant is added as a reducing liquid; the two solutions are mixed and reacted at a set temperature for 5 to 60 minutes, and the required alloy powder is obtained by precipitation, washing and drying. The method adopts the common liquid phase reduction method to synthesize monodisperse gold, platinum and palladium alloy microspheres. The gold, platinum and palladium obtained by this method are uniformly spherical, have good dispersibility, and controllable particle size. The slurry is prepared as LTCC solderable electronic slurry, which has very good printability, leveling, solderability and electrical properties. However, the particles prepared by this method have a low degree of alloying due to the reaction under low temperature conditions, and the nitrogen oxides produced by the dissolution of precious metals in aqua regia seriously pollute the environment. If the nitrate is not removed or the removal is not thorough, the reduction efficiency is low, resulting in a low direct yield.

[0004] The Chinese invention patent application with publication number CN104338530A discloses a supported gold-platinum-palladium catalyst with anti-sintering performance and a preparation method thereof. The method provides a supported gold-platinum-palladium catalyst with anti-sintering performance, which is composed of gold-platinum-palladium alloy nanoparticles supported on a porous carrier, the weight ratio of platinum to palladium is 1:4 to 2:1, and the size is less than 10nm. The method uses a one-step co-photodeposition method to prepare the catalyst, and maintains a uniform alloy structure at a calcination temperature above 700°C. Each uniform alloy structure is evenly distributed with three metals of gold, platinum and palladium, and the three metals are all in a metallic valence state, forming a single-phase alloy structure. The characteristics of this method are: 1) The prepared gold-platinum-palladium trimetallic catalyst has excellent anti-sintering performance; 2) It solves the problem that the gold-platinum-palladium catalyst is easily sintered and deactivated in high-temperature reactions above 700°C, and expands its high-temperature catalytic application, such as methane activation, automobile exhaust treatment, alkane oxidation and other high-temperature reactions; 3) The preparation method is simple and suitable for large-scale industrial production. However, the gold, platinum and palladium prepared by this method are synthesized on a carrier, and it is difficult to separate the alloy powder from the carrier. The process is complicated and not conducive to large-scale production.

[0005] Therefore, people are in urgent need of a method for preparing gold, platinum and palladium powder for high-performance composite electronic paste. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing gold, platinum and palladium for electronic paste in view of the above-mentioned deficiencies of the prior art. The technical solution adopted by the present invention is: a method for preparing gold, platinum and palladium for electronic paste, the method comprising the following steps.

[0007] Step 1: high-energy ball mill gold powder, platinum powder, palladium powder and aluminum powder to obtain gold-platinum-palladium-aluminum mixed powder.

[0008] Step 2: Dissolve the gold, platinum, palladium and aluminum mixed powder in alkali at high temperature to obtain a gold, platinum, palladium and aluminum suspension solution.

[0009] Step 3: Filter, wash and dry the gold-platinum-palladium aluminum-containing suspension solution to obtain gold-platinum-palladium powder.

[0010] Step 4: annealing the gold, platinum and palladium powder in a tube furnace to finally obtain gold, platinum and palladium alloy powder.

[0011] Compared with the method for preparing gold, platinum and palladium by traditional liquid phase reduction, the particle size distribution of gold, platinum and palladium powder prepared by liquid phase reduction is difficult to reach the micron level, and the requirement of gold, platinum and palladium slurry for powder is micron level, the obtained powder is easy to agglomerate, the dispersant is difficult to clean, and the obtained powder is difficult to be fully alloyed. The present invention directly mixes gold powder, platinum powder, palladium powder and aluminum powder for full ball milling, ensures the alloying degree of the powder, and then removes the aluminum in the alloy by high temperature alkali dissolution, ensures that only gold, platinum and palladium are left in the alloy, and finally forms micron-level spherical gold, platinum and palladium powder by annealing and calcining, and the process further ensures the alloying of the powder, and regulates the particle size and morphology of the powder, ensuring that the powder is micron-level spherical. Since the gold, platinum and palladium slurry needs to have good fluidity and viscosity in the application process of electronic slurry, and the slurry made of spherical powder has good fluidity and viscosity, which is conducive to the application of slurry, therefore, the micron-level spherical gold, platinum and palladium powder obtained by the preparation method of the present invention is suitable for the use of gold, platinum and palladium electronic slurry.

[0012] The above-mentioned method for preparing gold, platinum and palladium for electronic paste, in step 1, the mass ratios of gold powder, platinum powder, palladium powder and aluminum powder are: 3 to 8 parts of gold powder, 2 to 6 parts of platinum powder, 1 to 4 parts of palladium powder, and 5 to 30 parts of aluminum powder. Then place it in a ball mill and ball mill it at a speed of 500r / min to 1000r / min for 2h to 24h to obtain a gold, platinum, palladium and aluminum mixed powder. The present invention controls the raw material powder ratio, and then fully ball mills it to fully mix the four metal powders and alloy them, thereby laying a good foundation for the preparation of the final alloy powder.

[0013] In the above-mentioned method for preparing gold, platinum and palladium for electronic paste, the high-temperature alkali dissolution process described in step 2 is: putting the gold, platinum, palladium and aluminum mixed powder into a sodium hydroxide solution, heating it to 40-90°C, stirring it for 2-24 hours, and obtaining a gold, platinum and palladium aluminum suspension solution. The present invention ensures the full dissolution of aluminum in the ball-milled gold, platinum, palladium and aluminum alloy powder by controlling the concentration, temperature and dissolution time of the alkali solution, avoiding the presence of aluminum in the final product, and facilitating the smooth progress of subsequent processes.

[0014] In the above-mentioned method for preparing gold, platinum and palladium for electronic paste, the filtering, washing and drying process described in step 3 is: filtering the aluminum-containing suspension solution, washing 5-15 times, drying, the drying temperature is 60-120°C, and the drying time is 2-14 hours to obtain gold, platinum and palladium powder. The present invention cleans the aluminum on the surface of the gold, platinum and palladium powder by controlling the filtering, washing and drying process, and dries it for standby use, thereby ensuring the purity of the gold, platinum and palladium.

[0015] In the above-mentioned method for preparing gold, platinum and palladium for electronic paste, the annealing process described in step 4 is: placing the gold, platinum and palladium powder in a tubular furnace, and keeping it warm for 2h-6h at a temperature of 200°C to 500°C in a hydrogen atmosphere to obtain a gold, platinum and palladium alloy. The present invention controls the calcination process of the gold, platinum and palladium powder so that the gold, platinum and palladium powder is fully alloyed, and the particle size and morphology of the gold, platinum and palladium alloy powder are regulated.

[0016] In the above-mentioned method for preparing gold, platinum and palladium for electronic paste, the gold, platinum and palladium powder for electronic paste described in step 4 is characterized by being spherical, 1-4 microns in size, and having a face-centered cubic monophasic solid solution structure. The present invention prepares gold, platinum and palladium powder for electronic paste having the above-mentioned properties, which has good fluidity and viscosity after being made into slurry, making it suitable for use in electronic related devices.

[0017] Compared with the prior art, the present invention has the following advantages: 1. The present invention successfully prepares gold-platinum-palladium alloy powder by controlling the mixed ball milling, alkali dissolution and annealing of metal powder. The process of the present invention is simple and stable, the alloying degree of the powder is high, the gold-platinum-palladium is uniformly spherical, has good dispersibility, and the particle size is controllable. The paste is prepared as LTCC solderable electronic paste, and has very good printability, leveling, solderability and electrical properties. The prepared gold-platinum-palladium alloy powder is suitable for electronic paste.

[0018] 2. The gold-platinum-palladium alloy powder for electronic paste prepared by the present invention is spherical, has a size of 1-4 microns, and a face-centered cubic monophasic solid solution structure, which meets the needs of electronic paste.

[0019] 3. The preparation method of the present invention stably and effectively controls the morphology and phase structure of gold, platinum and palladium, has a simple process, a high yield, a large output, and is easy for industrial production.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of the preparation method of gold-platinum-palladium alloy powder for electronic paste.

[0022] Figure 2 This is a SEM image of the gold-platinum-palladium alloy powder for electronic paste prepared in Example 1 of the present invention.

[0023] Figure 3 This is the XRD pattern of the gold-platinum-palladium alloy powder for electronic paste prepared in Example 1 of the present invention. Implementation

[0024] The present invention will be further described below with reference to the embodiments.

[0025] Example 1.

[0026] like Figure 1 As shown, this embodiment includes the following steps.

[0027] Step 1: Mix 3 parts of gold powder, 2 parts of platinum powder, 4 parts of palladium powder and 30 parts of aluminum powder, then place them in a ball mill and mill them at a speed of 1000 r / min for 12 hours to obtain a gold, platinum, palladium and aluminum mixed powder.

[0028] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 24 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0029] Step 3: Filter the aluminum-containing suspension solution, wash it 10 times, and dry it at a drying temperature of 100° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0030] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 300° C. for 4 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0031] Figure 2 This is the SEM image of the gold-platinum-palladium alloy powder for electronic paste prepared in this embodiment. Figure 2 It can be seen that the gold-platinum-palladium alloy powder for electronic paste prepared in this embodiment has a microscopic morphology of spherical powder, a size of 1-4 microns, and a face-centered cubic monomial solid solution structure.

[0032] Figure 3 The XRD pattern of the gold-platinum-palladium alloy powder for electronic paste prepared in this embodiment is as follows: Figure 3 It can be seen that the gold-platinum-palladium alloy powder for electronic paste prepared in this embodiment has high phase purity and is gold-platinum-palladium alloy powder without other impurities.

[0033] Example 2.

[0034] like Figure 1 As shown, this embodiment includes the following steps.

[0035] Step 1: Mix 4 parts of gold powder, 3 parts of platinum powder, 3 parts of palladium powder, and 28 parts of aluminum powder, then place them in a ball mill and ball mill them at a speed of 1000 r / min for 12 hours to obtain a gold, platinum, palladium, and aluminum mixed powder.

[0036] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 24 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0037] Step 3: Filter the aluminum-containing suspension solution, wash it 10 times, and dry it at a drying temperature of 100° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0038] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 300° C. for 6 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0039] Comparing the test results of the gold-platinum-palladium alloy powder prepared in this example with those in Example 1, it can be seen that the particle size and morphology of the ruthenium oxide powder do not change much, and the powder has a face-centered cubic monomial solid solution structure.

[0040] Example 3.

[0041] like Figure 1 As shown, this embodiment includes the following steps.

[0042] Step 1: Mix 5 parts of gold powder, 3 parts of platinum powder, 3 parts of palladium powder, and 20 parts of aluminum powder, then place them in a ball mill and ball mill them at a speed of 1000 r / min for 12 hours to obtain a gold, platinum, palladium, and aluminum mixed powder.

[0043] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 4 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0044] Step 3: Filter the aluminum-containing suspension solution, wash it 10 times, and dry it at a drying temperature of 100° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0045] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 300° C. for 4 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0046] Comparing the test results of the gold-platinum-palladium alloy powder prepared in this example with those in Example 1, it can be seen that the particle size and morphology of the ruthenium oxide powder do not change much, and the XRD results show an aluminum characteristic peak in addition to the gold-platinum-palladium alloy powder. This is because the alkali dissolution time is reduced and the aluminum is not fully dissolved.

[0047] Example 4.

[0048] like Figure 1 As shown, this embodiment includes the following steps.

[0049] Step 1: Mix 5 parts of gold powder, 4 parts of platinum powder, 2 parts of palladium powder, and 18 parts of aluminum powder, then place them in a ball mill and ball mill them at a speed of 500 r / min for 3 hours to obtain a gold, platinum, palladium, and aluminum mixed powder.

[0050] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 24 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0051] Step 3: Filter the aluminum-containing suspension solution, wash it 10 times, and dry it at a drying temperature of 100° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0052] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 300° C. for 4 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0053] Comparing the test results of the gold-platinum-palladium alloy powder prepared in this example with those in Example 1, it can be seen that the particle size and morphology of the ruthenium oxide powder did not change much, and the XRD results showed mixed peaks. This is because the ball milling speed and time were not enough, resulting in insufficient alloying of the ball milled powder.

[0054] Example 5.

[0055] like Figure 1 As shown, this embodiment includes the following steps.

[0056] Step 1: Mix 6 parts of gold powder, 4 parts of platinum powder, 2 parts of palladium powder, and 13 parts of aluminum powder, then place them in a ball mill and ball mill them at a speed of 1000 r / min for 12 hours to obtain a gold, platinum, palladium, and aluminum mixed powder.

[0057] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 24 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0058] Step 3: Filter the aluminum-containing suspension solution, wash it 10 times, and dry it at a drying temperature of 100° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0059] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 500° C. for 6 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0060] Comparing the test results of the gold-platinum-palladium alloy powder prepared in this embodiment with those in Example 1, it can be seen that the XRD shows a face-centered cubic monophasic solid solution structure, the particle size and morphology of the ruthenium oxide powder have changed, and agglomeration has occurred. This is because the calcination temperature and time are too long, causing the gold-platinum-palladium to grow and agglomerate.

[0061] Example 6.

[0062] like Figure 1 As shown, this embodiment includes the following steps.

[0063] Step 1: Mix 7 parts of gold powder, 5 parts of platinum powder, 2 parts of palladium powder, and 8 parts of aluminum powder, then place them in a ball mill and ball mill them at a speed of 1000 r / min for 12 hours to obtain a gold, platinum, palladium, and aluminum mixed powder.

[0064] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 24 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0065] Step 3: Filter the aluminum-containing suspension solution, wash it 5 times, and dry it at a drying temperature of 100° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0066] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 300° C. for 4 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0067] Comparing the test results of the gold-platinum-palladium alloy powder prepared in this example with those in Example 1, it can be seen that the particle size and morphology of the ruthenium oxide powder do not change much. In addition to the gold-platinum-palladium alloy powder, the XRD results also show a small amount of aluminum characteristic peaks. This is because the number of cleaning times is too small and the aluminum is not fully dissolved.

[0068] Example 7.

[0069] like Figure 1 As shown, this embodiment includes the following steps.

[0070] Step 1: Mix 8 parts of gold powder, 6 parts of platinum powder, 1 part of palladium powder, and 5 parts of aluminum powder, then place them in a ball mill and ball mill them at a speed of 1000 r / min for 12 hours to obtain a gold, platinum, palladium, and aluminum mixed powder.

[0071] Step 2: Place the gold, platinum, palladium, and aluminum mixed powder into a sodium hydroxide solution, heat to 90° C., and stir for 24 hours to obtain a gold, platinum, palladium, and aluminum suspension solution.

[0072] Step 3: Filter the aluminum-containing suspension solution, wash it 10 times, and dry it at a drying temperature of 80° C. for 8 hours to obtain gold, platinum, and palladium powder.

[0073] Step 4: Place the gold-platinum-palladium powder in a tubular furnace, and keep it warm at 300° C. for 4 hours in a hydrogen atmosphere to obtain a gold-platinum-palladium alloy.

[0074] Comparing the test results of the gold-platinum-palladium alloy powder prepared in this example with those in Example 1, it can be seen that the particle size and morphology of the ruthenium oxide powder do not change much, and the powder has a face-centered cubic monomial solid solution structure.

[0075] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing gold, platinum and palladium for electronic paste, characterized in that: The method comprises the following steps: Step 1: high-energy ball milling gold powder, platinum powder, palladium powder and aluminum powder to obtain gold-platinum-palladium-aluminum mixed powder; Step 2, subjecting the gold, platinum, palladium and aluminum mixed powder to high-temperature alkali dissolution to obtain a gold, platinum, palladium and aluminum suspension solution; Step 3, filtering, washing and drying the gold-platinum-palladium aluminum-containing suspension solution to obtain gold-platinum-palladium powder; Step 4: annealing the gold-platinum-palladium powder in a tube furnace to finally obtain a gold-platinum-palladium alloy powder; The weight ratios of the gold powder, platinum powder, palladium powder and aluminum powder are as follows: 3 to 8 parts of gold powder, 2 to 6 parts of platinum powder, 1 to 4 parts of palladium powder, and 5 to 30 parts of aluminum powder; The high temperature alkali dissolution process is as follows: placing the gold, platinum, palladium and aluminum mixed powder into a sodium hydroxide solution, heating to 40-90° C., stirring for 2-24 hours, and obtaining a gold, platinum, palladium and aluminum suspension solution; The gold, platinum and palladium powder for electronic paste is characterized by being spherical, 1-4 microns in size and having a face-centered cubic monophasic solid solution structure; The annealing process described in step 4 is: placing the gold-platinum-palladium powder in a tubular furnace, keeping it warm at 200°C~500°C in a hydrogen atmosphere for 2h-6h to obtain the gold-platinum-palladium alloy powder.

2. The method for preparing gold, platinum and palladium for electronic paste according to claim 1, characterized in that: The ball milling process in step 1 is as follows: placing gold powder, platinum powder, palladium powder and aluminum powder in a ball mill and ball milling them at a rotation speed of 500 r / min~1000 r / min for 2h~24h to obtain a gold, platinum, palladium and aluminum mixed powder.

3. The method for preparing gold, platinum and palladium for electronic paste according to claim 1, characterized in that: The filtering, washing and drying process in step three is as follows: filtering the aluminum-containing suspension solution, washing it 5-15 times, and drying it at a drying temperature of 60-120° C. for a drying time of 2-14 hours to obtain gold, platinum and palladium powder.

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