A method for preparing platinum powder for platinum-silver paste and application thereof

Abstract

The present application belongs to the technical field of electrode paste, and relates to a preparation method of platinum powder for platinum-silver paste and application of the platinum powder. The preparation method comprises the steps of preparing surface-activated platinum powder and preparing a mixture containing a magnetic composite platinum powder precursor; and an electrode paste containing the platinum powder is also provided. The conductivity, stability and corrosion resistance of the electrode paste are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of electrode paste technology, and relates to a method for preparing platinum powder for platinum-silver paste and its application. Background Technology

[0002] Platinum-silver paste, as an important electronic material, plays a crucial role in the electronics industry. It consists of three parts: platinum powder, glass powder, and a carrier. Each part performs a specific function, and together they determine the properties of the paste.

[0003] As a high-performance electronic packaging material, platinum-silver paste's core components—platinum powder, glass powder, and carrier—directly determine the electrical performance and reliability of the final product. Currently, this material system exhibits problems such as insufficient conductivity, poor high-temperature stability, and poor corrosion resistance during application. These issues are closely related to the material composition ratio, microstructure, and preparation process. Conductivity defects mainly stem from discontinuous conductive pathways caused by uneven platinum powder distribution, interfacial stress caused by the mismatch in thermal expansion coefficients between the glass phase and the substrate, and micropore defects caused by residual volatilization from the carrier system. High-temperature performance issues are related to decreased grain boundary stability due to insufficient platinum powder content and a low softening temperature of the glass phase. Insufficient corrosion resistance is attributed to the formation of an oxide film on the platinum powder surface and insufficient chemical stability of the glass phase.

[0004] To address the aforementioned issues, extensive research and exploration have been conducted both within and outside the industry, resulting in a variety of solutions. However, the performance of traditional platinum-silver pastes still requires further optimization to meet the increasingly demanding requirements of electronic packaging. Summary of the Invention

[0005] This invention proposes a novel method for preparing platinum powder for platinum-silver paste, aiming to solve the problems existing in the prior art. Through innovative platinum powder modification methods, optimized glass powder formulations, and suitable carrier components, this invention achieves a significant improvement in the performance of platinum-silver paste, providing a new technical path for the development of electronic materials.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing platinum powder for platinum-silver paste, wherein the platinum powder is modified platinum powder, and the method for preparing the modified platinum powder includes the following steps: S1. Platinum powder is placed in a low-temperature plasma treatment device for activation treatment. A mixed gas of Ar and O2 with a volume ratio of 3:1-5:1 is used as the working gas. The treatment is carried out for 5-8 minutes under a radio frequency power of 50W to obtain surface-activated platinum powder. S2. Mix surface-activated platinum powder and silicon carbide coupled magnetic beads at a mass ratio of 10:1-20:1, add 3-mercaptopropyltriethoxysilane and polyvinylpyrrolidone, disperse by ultrasonication for 30-35 min, and stir and react in a constant temperature water bath at 60-70℃ for 3-5 h to obtain a mixture containing magnetic composite platinum powder precursor. S3. A permanent magnet separation device was used to perform magnetic separation on the mixture containing the magnetic composite platinum powder precursor. The lower precipitate was collected and washed three times each with deionized water and anhydrous ethanol, and then vacuum dried at 60°C for 2-2.5 h to obtain modified platinum powder. The preparation method of silicon carbide coupling magnetic beads is as follows: 1) Sonicate silicon carbide powder with 5M HCl for 30-35 min, then vacuum dry at 70-90℃ for 1-2 h to obtain pretreated silicon carbide powder; 2) Refrigerate the pretreated silicon carbide powder with KH-560 solution (pH 3.5-4.0) at 55-65℃ for 3-5 hours; then add distearate isopropylsilane and continue the reaction for 1.5-2.5 hours to obtain silanized silicon carbide; 3) React silanized silicon carbide and amino magnetic beads in PBS buffer (pH 6.0) with shaking at 55-65°C for 5-7 hours.

[0008] Preferably, the amount of 3-mercaptopropyltriethoxysilane is 1-3 wt% (this percentage represents the weight of 3-mercaptopropyltriethoxysilane to the total weight of the entire reaction mixture), and the amount of polyvinylpyrrolidone is 0.5-1.5 wt% (this percentage represents the weight of polyvinylpyrrolidone to the total weight of the entire reaction mixture). The reaction mixture comprises surface-activated platinum powder, silicon carbide coupling magnetic beads, 3-mercaptopropyltriethoxysilane, and polyvinylpyrrolidone.

[0009] Preferably, the mass ratio of silicon carbide powder to KH-560 is 1:0.05, the mass ratio of silicon carbide powder to distearate isopropylsilane is 1:0.03, and the mass ratio of silanized silicon carbide to amino magnetic beads is 1:1.5.

[0010] Secondly, a platinum powder for use in platinum-silver paste is provided, wherein the platinum powder is prepared by the preparation method described in this invention.

[0011] Thirdly, a platinum-silver paste is provided, wherein the platinum-silver paste comprises the platinum powder described in this invention.

[0012] Fourthly, a platinum-silver paste is provided, comprising, by weight, 29-30 parts of platinum powder as described in this invention, 5-6 parts of glass powder, and 7-8 parts of carrier.

[0013] Preferably, the platinum-silver paste comprises 29.5 parts of platinum powder as described in this invention, 5.5 parts of glass powder, and 7.5 parts of carrier.

[0014] Preferably, the glass powder is composed of 20-25 parts SiO2, 16-18 parts B2O3, 14-20 parts Al2O3, 3-6 parts CuO, 1-2 parts ZrO2 and 0.5-1.5 parts IrO2.

[0015] More preferably, the glass powder is composed of 22.5 parts SiO2, 17 parts B2O3, 17 parts Al2O3, 4.5 parts CuO, 1.5 parts ZrO2 and 0.5 parts IrO2.

[0016] Preferably, the carrier is ethyl cellulose resin and terpineol.

[0017] More preferably, the mass ratio of the ethyl cellulose resin to the terpineol is 1:4 to 1:6.

[0018] In this invention, by adjusting the mass ratio of ethyl cellulose resin to terpineol in the carrier to a range of 1:4 to 1:6, trace amounts of carbon residue can be ensured, which avoids both conductive loss and the introduction of insulating phase, and forms an interfacial gradient layer at the glass-metal interface, thereby improving corrosion resistance and water resistance.

[0019] It should be noted that the carrier of this invention can uniformly disperse the modified platinum powder and glass powder, avoiding agglomeration. This uniformity is a prerequisite for the glass powder to uniformly coat the modified platinum powder during subsequent sintering. Without the carrier of this invention, the dispersion may be uneven, resulting in localized exposure of platinum powder (easy oxidation) or excess glass powder (leading to poor conductivity), which will directly reduce high-temperature stability.

[0020] Fifthly, a method for preparing the platinum-silver paste according to the present invention is provided, wherein the preparation method is as follows: After melting the components in the glass powder, the powder is ball-milled to a particle size ≤1μm. The mixture of platinum powder, glass powder and carrier is then ground using a three-roll mill.

[0021] Sixthly, the invention provides the application of the platinum powder or platinum-silver paste described in this invention in improving the performance of electronic devices, wherein the performance of the electronic devices includes conductivity, high-temperature stability, and / or corrosion resistance.

[0022] Preferably, the electronic device is a flexible electronic sensor, a magnetic biosensor, or a microfluidic chip electrode.

[0023] In a seventh aspect, the application of the platinum powder or platinum-silver paste described in this invention in the preparation of conductive materials, wherein the conductive materials are electromagnetic shielding and absorbing materials and / or self-healing materials.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention significantly improves the conductivity, high-temperature stability, corrosion resistance, and water resistance of platinum-silver paste by introducing modified platinum powder, optimizing the preparation method of silicon carbide coupled magnetic beads, and improving the glass powder formulation and carrier composition. The platinum-silver paste of this invention is suitable for the encapsulation and protection of various high-performance electronic devices. Specifically, (1) Improved conductivity: On the one hand, in the preparation of silicon carbide coupled magnetic beads, KH-560 first reacts with the hydroxyl groups on the surface of silicon carbide to form covalent bonds and introduce epoxy groups; then it is modified by distearyloxyisopropylsilane, which not only enhances the chemical bonding with amino magnetic beads, but also reduces the surface energy through long-chain alkyl groups. This structure can form a stable composite network when combined with surface-activated platinum powder (low-temperature plasma treatment generates hydroxyl groups and unsaturated bonds on the surface of platinum powder) and 3-mercaptopropyltriethoxysilane; polyvinylpyrrolidone is adsorbed on the surface of the composite network, and prevents agglomeration through steric hindrance, ensuring uniform dispersion of platinum powder, reducing the break points of conductive pathways, thereby improving conductivity. In addition, after sintering, the magnetic beads can act as microcapacitor nodes in the composite network, balancing the current distribution, suppressing local Joule heating, and thus maintaining low resistivity. On the other hand, the ethyl cellulose resin and terpineol in the carrier give the slurry a suitable viscosity, which can be evenly spread through screen printing and ensure that the modified platinum powder is evenly distributed during the printing process, avoiding sedimentation. During sintering, terpineol volatilizes first and ethyl cellulose decomposes gradually, providing space for the glass powder to melt and flow. This allows the glass powder to fill the gaps between the modified platinum powders. The silane layer on the surface of the modified platinum powder forms Si-O-Si bonds with the SiO2 in the glass powder, making the platinum powder and the glass phase tightly bonded. This not only avoids voids after sintering and reduces the breakage of conductive pathways, but also maintains the continuous network of platinum powder through the supporting effect of the glass phase, thereby further reducing resistivity and improving conductivity.

[0025] (2) Improved high-temperature stability: On the one hand, the composite structure of silicon carbide and amino magnetic beads itself has high-temperature stability. The Si-O-Si bonds formed after the hydrolysis of KH-560 are stable at high temperatures, providing a rigid framework for the composite structure and resisting thermal shock. At the same time, the long-chain alkyl group of distearate isopropylsilane decomposes slowly at high temperatures, avoiding structural damage caused by violent gas production. After this magnetic bead (silicon carbide coupled magnetic bead) is combined with surface-activated platinum powder, the Si-O bonds formed by 3-mercaptopropyltriethoxysilane are heat-resistant and can resist thermal shock at 500℃. Ultimately, the core-shell or embedded structure formed by the combination of silicon carbide coupled magnetic beads, surface-activated platinum powder and 3-mercaptopropyltriethoxysilane maintains the integrity of particle morphology and conductive network at high temperatures. That is, the core-shell or embedded structure maintains structural integrity at high temperatures, does not agglomerate or oxidize, and maintains the stability of the conductive network. On the other hand, the carrier of this invention can also uniformly disperse the modified platinum powder and glass powder, avoiding agglomeration. The combination of the three ultimately achieves the integrity of the structure of the platinum-silver paste under long-term aging at 500℃, without oxidation or cracking, significantly improving high-temperature stability.

[0026] (3) Improved corrosion resistance and water resistance: On the one hand, after modification with KH-560 and distearate isopropylsilane, silicon carbide forms a composite layer with both polarity and hydrophobicity on its surface. The polar groups can condense with the silanol groups of 3-mercaptopropyltriethoxysilane on the surface of the activated platinum powder to form a dense cross-linked structure; the hydrophobic long chains hinder the penetration of water and acidic media. At the same time, polyvinylpyrrolidone is adsorbed on the surface of intermediate particles formed by the connection of activated platinum powder and silicon carbide coupled magnetic beads through 3-mercaptopropyltriethoxysilane. This not only prevents agglomeration, but its polar segments can also form hydrogen bonds with the silane layer, further strengthening the interface and preventing water and corrosive liquid from seeping into the surface of the platinum powder from the gaps. This makes the platinum silver paste less susceptible to corrosion in water and acidic environments, indirectly ensuring the integrity of the conductive network. On the other hand, the trace amounts of ethyl cellulose carbonization products remaining in the carrier form a "carbon-glass" gradient layer at the glass-metal interface, improving the interfacial bonding strength and ensuring that the tape does not fall off during the tear test. Detailed Implementation

[0027] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0028] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials are all commercially available.

[0029] The silicon carbide powder was purchased from Shanghai Bike New Materials Technology Co., Ltd., with a purity of 99.9%.

[0030] The amino magnetic beads were purchased from Suzhou Beaver Biomedical Engineering Co., Ltd., with an average particle size of 2 μm.

[0031] Example 1 This embodiment provides a platinum-silver paste, which comprises 29 parts platinum powder, 5 parts glass powder and 7 parts carrier by weight. The glass powder is composed of 20 parts SiO2, 16 parts B2O3, 14 parts Al2O3, 3 parts CuO, 1 part ZrO2 and 0.5 parts IrO2; The carrier is ethyl cellulose resin and terpineol, and the mass ratio of ethyl cellulose resin to terpineol is 1:4-1:6. The platinum powder is modified platinum powder, and the preparation method of the modified platinum powder includes the following steps: S1. Platinum powder was placed in a low-temperature plasma treatment device for activation treatment. A mixture of Ar and O2 with a volume ratio of 3:1 was used as the working gas. The treatment was carried out for 5 minutes at a radio frequency power of 50W to obtain surface-activated platinum powder. S2. Surface-activated platinum powder and silicon carbide coupled magnetic beads are mixed at a mass ratio of 10:1. 3-mercaptopropyltriethoxysilane and polyvinylpyrrolidone are added. After ultrasonic dispersion for 30 min, the mixture is stirred and reacted in a constant temperature water bath at 60℃ for 5 h to obtain a mixture containing magnetic composite platinum powder precursor. S3. A permanent magnet separation device was used to perform magnetic separation on the mixture containing the magnetic composite platinum powder precursor. The lower precipitate was collected and washed three times each with deionized water and anhydrous ethanol, and then dried under vacuum at 60°C for 2 hours to obtain modified platinum powder. The preparation method of silicon carbide coupling magnetic beads is as follows: 1) Silicon carbide powder was ultrasonically treated with 5M HCl for 30 min and then vacuum dried at 70℃ for 1 h to obtain pretreated silicon carbide powder; 2) The pretreated silicon carbide powder was refluxed with KH-560 solution at 55°C for 3 hours, pH 3.5; then distearate isopropylsilane was added and the reaction was continued for 1.5 hours to obtain silanized silicon carbide; 3) Silanized silicon carbide and amino magnetic beads were reacted in PBS buffer (pH 6.0) at 55°C with shaking for 5 hours; The amount of 3-mercaptopropyltriethoxysilane used is 1 wt%, the amount of polyvinylpyrrolidone used is 0.5 wt%, the mass ratio of silicon carbide powder to KH-560 is 1:0.05, the mass ratio of silicon carbide powder to distearyloxyisopropylsilane is 1:0.03, and the mass ratio of silanized silicon carbide to amino magnetic beads is 1:1.5.

[0032] Example 2 This embodiment provides a platinum-silver paste, which comprises 30 parts platinum powder, 6 parts glass powder and 8 parts carrier by weight. The glass powder is composed of 25 parts SiO2, 18 parts B2O3, 20 parts Al2O3, 6 parts CuO, 2 parts ZrO2 and 1.5 parts IrO2; The carrier is ethyl cellulose resin and terpineol, with a mass ratio of ethyl cellulose resin to terpineol of 1:6. The platinum powder is modified platinum powder, and the preparation method of the modified platinum powder includes the following steps: S1. Platinum powder was placed in a low-temperature plasma treatment device for activation treatment. A mixed gas of Ar and O2 with a volume ratio of 5:1 was used as the working gas. The treatment was carried out for 8 minutes under a radio frequency power of 50W to obtain surface-activated platinum powder. S2. Surface-activated platinum powder and silicon carbide coupled magnetic beads are mixed at a mass ratio of 20:1. 3-mercaptopropyltriethoxysilane and polyvinylpyrrolidone are added. After ultrasonic dispersion for 35 min, the mixture is stirred and reacted in a constant temperature water bath at 70℃ for 5 h to obtain a mixture containing magnetic composite platinum powder precursor. S3. A permanent magnet separation device was used to perform magnetic separation on the mixture containing the magnetic composite platinum powder precursor. The lower precipitate was collected and washed three times each with deionized water and anhydrous ethanol, and then dried under vacuum at 60°C for 2.5 h to obtain modified platinum powder. The preparation method of silicon carbide coupling magnetic beads is as follows: 1) Silicon carbide powder was ultrasonically treated with 5M HCl for 35 min and then vacuum dried at 90℃ for 2 h to obtain pretreated silicon carbide powder; 2) The pretreated silicon carbide powder was refluxed with KH-560 solution at 65℃ for 5 hours, pH 3.5; then distearate isopropylsilane was added and the reaction was continued for 2.5 hours to obtain silanized silicon carbide; 3) Silanized silicon carbide and amino magnetic beads were reacted in PBS buffer (pH 6.0) at 65°C with shaking for 7 hours; The amount of 3-mercaptopropyltriethoxysilane used is 3 wt%, the amount of polyvinylpyrrolidone used is 1.5 wt%, the mass ratio of silicon carbide powder to KH-560 is 1:0.05, the mass ratio of silicon carbide powder to distearyloxyisopropylsilane is 1:0.03, and the mass ratio of silanized silicon carbide to amino magnetic beads is 1:1.5.

[0033] Example 3 This embodiment provides a platinum-silver paste, which comprises 29.5 parts platinum powder, 5.5 parts glass powder, and 7.5 parts carrier by weight. The glass powder is composed of 22.5 parts SiO2, 17 parts B2O3, 17 parts Al2O3, 4.5 parts CuO, 1.5 parts ZrO2 and 0.5 parts IrO2; The carrier is ethyl cellulose resin and terpineol, with a mass ratio of ethyl cellulose resin to terpineol of 1:4. The platinum powder is modified platinum powder, and the preparation method of the modified platinum powder includes the following steps: S1. Platinum powder was placed in a low-temperature plasma treatment device for activation treatment. A mixed gas of Ar and O2 with a volume ratio of 5:1 was used as the working gas. The treatment was carried out for 5 minutes under a radio frequency power of 50W to obtain surface-activated platinum powder. S2. Surface-activated platinum powder and silicon carbide coupled magnetic beads are mixed at a mass ratio of 10:1. 3-mercaptopropyltriethoxysilane and polyvinylpyrrolidone are added. After ultrasonic dispersion for 30 min, the mixture is stirred and reacted in a constant temperature water bath at 60℃ for 3 h to obtain a mixture containing magnetic composite platinum powder precursor. S3. A permanent magnet separation device was used to perform magnetic separation on the mixture containing the magnetic composite platinum powder precursor. The lower precipitate was collected and washed three times each with deionized water and anhydrous ethanol, and then dried under vacuum at 60°C for 2 hours to obtain modified platinum powder. The preparation method of silicon carbide coupling magnetic beads is as follows: 1) Silicon carbide powder was ultrasonically treated with 5M HCl for 30 min and then vacuum dried at 80℃ for 2 h to obtain pretreated silicon carbide powder; 2) The pretreated silicon carbide powder was refluxed with KH-560 solution at 60℃ for 4 hours, pH 3.5; then distearate isopropylsilane was added and the reaction was continued for 2 hours to obtain silanized silicon carbide; 3) Silanized silicon carbide and amino magnetic beads were reacted in PBS buffer (pH 6.0) at 60°C with shaking for 6 hours; The amount of 3-mercaptopropyltriethoxysilane used is 3 wt%, the amount of polyvinylpyrrolidone used is 1.5 wt%, the mass ratio of silicon carbide powder to KH-560 is 1:0.05, the mass ratio of silicon carbide powder to distearyloxyisopropylsilane is 1:0.03, and the mass ratio of silanized silicon carbide to amino magnetic beads is 1:1.5.

[0034] Example 4 This embodiment provides a method for preparing platinum-silver paste, the method comprising: Preparation of glass powder: Each component of the glass powder is put into a corundum crucible and placed in a high-temperature melting furnace. The temperature is increased to 1450-1500℃ at 10℃ / min and held for melting for 2-3 hours to form a homogeneous glass melt. The molten glass is poured into deionized water and quenched to obtain broken glass pieces. Glass blocks and zirconia grinding balls (ball-to-material mass ratio 3:1) were loaded into a ball mill jar, and anhydrous ethanol was added as a medium. The mixture was then ball-milled in a planetary ball mill at 300 r / min for 4-6 h to obtain glass powder slurry. The glass powder slurry was vacuum dried at 80℃ for 2 hours and then passed through a 300-mesh sieve to obtain glass powder with a particle size ≤1μm. Preparation of carriers: Ethyl cellulose resin was slowly added to terpineol and stirred at 200 r / min in a 60°C water bath until completely dissolved, forming a transparent viscous liquid. The mixture was then allowed to stand for 1 hour to remove bubbles before use. Preparation of platinum-silver paste: After mixing the modified platinum powder, glass powder and carrier, the mixture is pre-dispersed in a planetary mixer at 200 r / min (60℃) for 30 min; then it is milled in a three-roll mill (the conditions for three-roll milling are: roller speed 200-300 r / min, milling time 2-3 h, roller temperature 25-40℃) to obtain the final product.

[0035] Example 5 This embodiment provides the application of the platinum-silver pastes of Examples 1-3 in improving the conductivity, high-temperature stability and corrosion resistance of electrodes in flexible electronic sensors, magnetic biosensors and microfluidic chips.

[0036] Regarding electrical conductivity: In Examples 1-3, platinum powder, after low-temperature plasma activation, increases surface active sites. When combined with silicon carbide coupled magnetic beads, and further processed with 3-mercaptopropyltriethoxysilane and polyvinylpyrrolidone, and then subjected to three-roll milling, platinum powder agglomeration is reduced, increasing the continuity of the conductive pathway. Platinum itself is a highly conductive noble metal, while glass powder, after high-temperature melting and ball milling, has a particle size ≤1μm, which can fill the gaps between platinum powder particles to form a dense structure, preventing the conductive pathway from breaking.

[0037] Flexible electronic sensors and microfluidic chip electrodes require continuous conductive paths, while magnetic biosensors need to possess both conductivity and magnetism (silicon carbide coupled magnetic beads provide magnetism without affecting the conductive network of platinum). Based on the characteristics of the uniformly dispersed highly conductive phase bonded to the dense glass phase, those skilled in the art can directly expect that the platinum-silver pastes of Examples 1-3 have better conductivity than unmodified or unevenly dispersed pastes.

[0038] Regarding high-temperature stability: Flexible electronic sensors need to withstand fluctuations in the operating environment temperature, magnetic biosensors need to withstand high sterilization temperatures, and microfluidic chip electrodes may need to come into contact with high-temperature reaction solutions. Based on the formulation design of the platinum-silver paste in Examples 1-3, those skilled in the art can expect it to maintain structural stability and no significant attenuation of conductivity in flexible electronic sensors, magnetic biosensors, and microfluidic chip electrodes.

[0039] Regarding corrosion resistance: Magnetic biosensors, microfluidic chip electrodes, and flexible electronic sensors are exposed to corrosive environments and are all subject to corrosion risks. Based on the formulation designs of the platinum-silver pastes in Examples 1-3, those skilled in the art can anticipate that these pastes will resist corrosive media and maintain stable performance in magnetic biosensors, microfluidic chip electrodes, and flexible electronic sensors.

[0040] Example 6 This embodiment provides the application of the platinum-silver pastes of Examples 1-3 in the preparation of electromagnetic shielding and absorbing materials and self-healing materials.

[0041] Based on conventional knowledge of material composition, microstructure, and performance relationships, combined with the design of the modified platinum powder, glass powder, and carrier system in Examples 1-3, and the precise process control such as three-roll milling, those skilled in the art can reasonably expect that the platinum-silver pastes in Examples 1-3 can be used to prepare electromagnetic shielding and absorbing materials as well as self-healing materials.

[0042] Comparative Example 1 This comparative example is the same as Example 3, except that the distearate isopropylsilane in the method for preparing silicon carbide coupled magnetic beads is replaced with dodecyltrimethoxysilane.

[0043] Comparative Example 2 This comparative example is the same as Example 3, except that KH-560 in the silicon carbide coupling magnetic bead preparation method is replaced with Dow Corning Z-6040.

[0044] Comparative Example 3 This comparative example is the same as Example 3, except that 3-mercaptopropyltriethoxysilane in the modified platinum powder preparation method is replaced with 3-mercaptopropyltrimethoxysilane.

[0045] Comparative Example 4 This comparative example is the same as Example 3, except that polyvinylpyrrolidone in the modified platinum powder preparation method is replaced with polyvinyl alcohol.

[0046] Effect verification Experimental subjects: Platinum-silver pastes prepared according to Example 4 in Examples 1-3 and Comparative Examples 1-4; Experimental methods: The above-mentioned platinum-silver paste was screen-printed onto 1206 alumina substrates (the substrates were ultrasonically cleaned with anhydrous ethanol for 10 min and dried at 120°C before use). The substrates were then dried at 130°C for 15 min, cured at 150°C for 30 min, and then heated to 850°C at 10°C / min in an air atmosphere muffle furnace and held for 10 min. The substrates were then cooled to room temperature in the furnace to obtain test samples, and finally, performance tests were conducted. Conductivity test: A four-probe resistivity / sheet resistance tester was used, with a probe spacing of 1 mm and a contact pressure of 0.3 N. The resistivity (μΩ·m) was measured at 5 different locations randomly selected from each sample, and the average value was taken as the final resistivity value of the sample.

[0047] High temperature stability test: Place the sample in a muffle furnace and age it at 500℃ for 300 hours in an air atmosphere. Observe whether cracks, peeling or oxidation discoloration appear on the surface of the sample. Corrosion resistance test: Immerse the sample in 20% dilute sulfuric acid solution for 96 hours, then peel the sample with 3M tape and observe whether it peels off. Experimental results are shown in Table 1.

[0048] Table 1 Performance test results of each group of samples

[0049] As shown in Table 1, the samples prepared using the platinum-silver paste of this invention exhibit excellent conductivity, high-temperature stability, and corrosion resistance. As a high-performance electronic packaging material, the platinum-silver paste of this invention, compared to platinum-silver paste without the formulation system of this invention, is well-suited for the packaging and protection of various high-performance electronic devices. Specifically, Regarding conductivity, the resistivity of each sample made from the platinum-silver paste of the present invention is relatively low, ranging from 15.2 to 17.0 μΩ·m. Among them, Example 3 has the lowest resistivity and the best conductivity. However, due to the replacement of key components, the resistivity of each sample in Comparative Examples 1-4 increased significantly, ranging from 38.9 to 43.0 μΩ·m.

[0050] Regarding high-temperature stability, under high-temperature conditions, the surface of the present invention remains intact, without cracks, peeling, or oxidation discoloration; while comparative examples 1-4, due to the replacement of key components, all groups of samples showed significant discoloration, cracks, or peeling, which means that they cannot maintain good stability under high-temperature conditions.

[0051] Regarding corrosion resistance, the coating of this invention remained intact without any peeling; however, comparative examples 1-4, due to the replacement of key components, showed a large amount of peeling in each group of samples, which means that they cannot maintain good stability in acidic environments.

[0052] The effect verification experiment shows that the platinum silver paste formulation system provided by the present invention is a whole. Specifically, the raw materials in the platinum silver paste support each other and have an interactive relationship. It is precisely because the raw materials support each other and have an interactive relationship that the platinum silver paste of the formulation system of the present invention has good conductivity, high temperature stability and corrosion resistance.

[0053] It should be understood that the disclosed invention is not limited to the specific methods, schemes, and substances described, as these are all subject to variation. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the invention, which is limited only by the appended claims.

Claims

1. A method for preparing platinum powder for platinum-silver paste, characterized in that, The platinum powder is modified platinum powder, and the preparation method of the modified platinum powder includes the following steps: S1. Platinum powder is placed in a low-temperature plasma treatment device for activation treatment to obtain surface-activated platinum powder; S2. Mix surface-activated platinum powder and silicon carbide coupled magnetic beads at a mass ratio of 10:1-20:1, add 3-mercaptopropyltriethoxysilane and polyvinylpyrrolidone, disperse by ultrasonication, and stir in a constant temperature water bath at 60-70℃ for 3-5 hours to obtain a mixture containing magnetic composite platinum powder precursor. S3. A permanent magnet separation device was used to perform magnetic separation on the mixture containing the magnetic composite platinum powder precursor. The lower precipitate was collected and washed three times each with deionized water and anhydrous ethanol, and then vacuum dried at 60°C for 2-2.5 h to obtain modified platinum powder. The preparation method of silicon carbide coupling magnetic beads is as follows: 1) Sonicate silicon carbide powder with 5M HCl for 30-35 min, then vacuum dry at 70-90℃ for 1-2 h to obtain pretreated silicon carbide powder; 2) The pretreated silicon carbide powder and KH-560 solution were refluxed at 55-65℃ for 3-5 hours; then distearate isopropylsilane was added and the reaction was continued for 1.5-2.5 hours to obtain silanized silicon carbide; 3) Silanized silicon carbide and amino magnetic beads were reacted in PBS buffer at 55-65℃ with shaking for 5-7 hours.

2. The preparation method according to claim 1, characterized in that, The amount of 3-mercaptopropyltriethoxysilane used is 1-3 wt%.

3. The preparation method according to claim 1, characterized in that, The amount of polyvinylpyrrolidone used is 0.5-1.5 wt%.

4. A platinum powder for use in platinum-silver paste, characterized in that, The platinum powder is prepared by the preparation method according to any one of claims 1-3.

5. A platinum-silver paste, characterized in that, The platinum-silver paste includes the platinum powder as described in claim 4.

6. A platinum-silver paste, characterized in that, The platinum-silver paste comprises, by weight, 29-30 parts of platinum powder as described in claim 4, 5-6 parts of glass powder, and 7-8 parts of carrier.

7. The platinum-silver paste according to claim 6, characterized in that, The glass powder is composed of 20-25 parts SiO2, 16-18 parts B2O3, 14-20 parts Al2O3, 3-6 parts CuO, 1-2 parts ZrO2 and 0.5-1.5 parts IrO2.

8. The platinum-silver paste according to claim 6, characterized in that, The carrier is ethyl cellulose resin and terpineol.

9. The use of the platinum powder according to claim 4 or the platinum-silver paste according to any one of claims 6-8 in the preparation of conductive materials, characterized in that, The conductive material is an electromagnetic shielding and absorbing material and / or a self-healing material.

10. The application of the platinum powder of claim 4 or the platinum-silver paste of any one of claims 6-8 in improving the performance of electronic devices, characterized in that, The electronic device's properties include conductivity, high-temperature stability, and / or corrosion resistance.

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