A method for preparing a low-oxygen-content silver evaporation material

Abstract

This invention belongs to the field of evaporation coating technology and relates to a method for preparing a low-oxygen silver evaporation coating material. The steps include: S1, casting an ingot; S2, turning; S3, heat preservation; S4, forming; S5, steel ball grinding; S6, ultrasonic cleaning; and S7, dehydration and drying. This method can remove the oxide layer on the surface of the silver ingot by turning, form it into a silver evaporation coating material, and then use steel ball grinding to remove a small amount of oxide layer on the surface of the silver evaporation coating material. Finally, the surface is ultrasonically cleaned to obtain a silver evaporation coating material with an oxygen content of less than 10 ppm. This avoids the problem of silver splashing caused by oxygen release during use and reduces material waste.

Description

Technical Field

[0001] This invention relates to the field of evaporation coating technology, and in particular to a method for preparing a silver evaporation coating material with low oxygen content. Background Technology

[0002] Evaporation coating technology is widely used in the semiconductor industry, and silver vapor deposition materials play a crucial role as the main material for silver films in semiconductor processes. However, high-purity silver vapor deposition materials currently on the market generally have a high oxygen content, which causes silver liquid to splash in the crucible during the evaporation process, resulting in significant losses and a decrease in the utilization rate of silver vapor deposition materials.

[0003] In existing technologies, the manufacturing process of silver vapor-deposited materials generally involves the following steps:

[0004] ① Electrolytic silver is melted into a liquid state, then kept at a certain temperature, and then cooled and shaped into silver ingots;

[0005] ② The silver ingots are subjected to a hot extrusion / granulation process to obtain intermediate material;

[0006] ③ The intermediate material is processed to obtain the silver vapor-plated material of the required size;

[0007] ④ Clean the formed silver vapor-plated material and then vacuum-pack it for storage.

[0008] The reason for the above problems is that when silver ingots are cast and cooled, they are inevitably exposed to the atmosphere. Electrolytic silver transforms from liquid to solid by passing through the melting point of silver (961.63℃). After undergoing a heat preservation process, at this temperature, oxygen molecules in the atmosphere first decompose into oxygen atoms. When these oxygen atoms come into contact with the surface of the silver ingot, they oxidize the surface silver atoms. This oxide layer cannot be effectively removed in subsequent steps. Therefore, the oxygen content of the silver ingot, intermediate material, and silver vapor deposition material remains above 100ppm. When the solid silver vapor deposition material is liquefied again, oxygen is released in large quantities as the temperature rises. In the environment of semiconductor industry applications, this manifests as oxygen bubbles being released from the silver liquid, causing a large amount of silver liquid to splash, resulting in the waste of silver material.

[0009] Therefore, it is necessary to develop a new process to solve the above problems. Summary of the Invention

[0010] The main objective of this invention is to provide a method for preparing silver vapor-deposited materials with low oxygen content, which can yield silver vapor-deposited materials with oxygen content as low as 10 ppm or less.

[0011] This invention achieves the above objective through the following technical solution: a method for preparing a low-oxygen-content silver vapor-deposited material, comprising the following steps:

[0012] S1. Casting: Electrolytic silver is melted until completely melted and then poured into a smooth silver ingot.

[0013] S2. Turning: Turn the surface of the silver ingot by 1-10 mm to obtain the turned silver ingot;

[0014] S3. Heat preservation: The machined silver ingot is kept in a vacuum environment at a temperature of 600-900℃ for 0.5-4 hours to obtain a heat-preserved silver ingot.

[0015] S4. Molding: The silver ingot, after being kept warm, is melted and shaped into the design size to obtain the silver vapor-plated material.

[0016] Specifically, the forming step involves extruding the silver ingot into wire of a designed diameter or granulating it into silver particles of a designed size.

[0017] Furthermore, the steps also include:

[0018] S5. Grinding with steel balls: Grind the silver vapor-plated material with stainless steel balls for 0.5 to 4 hours. Wash the grinding debris clean and sieve to obtain the ground silver vapor-plated material.

[0019] S6. Ultrasonic cleaning: Place the ground silver vapor-deposited material into an organic solvent and clean it under an ultrasonic atmosphere for 5-60 minutes. After taking it out, add it back into pure water and clean it again under an ultrasonic atmosphere for 5-60 minutes to obtain the cleaned silver vapor-deposited material.

[0020] S7. Dehydration and drying: Remove the moisture from the surface of the cleaned silver vapor-plated material to obtain a dry silver vapor-plated material.

[0021] Furthermore, the steel balls used in the steel ball grinding step are stainless steel balls with a diameter of 2 to 10 mm.

[0022] Furthermore, an oil-removing agent is added during the grinding of the steel balls, and the oil-removing agent is an aqueous solution containing a surfactant.

[0023] Furthermore, the organic solvent is acetone.

[0024] Specifically, the forming step involves pressing the silver sheet into a design thickness.

[0025] The beneficial effects of the technical solution of this invention are:

[0026] This method can remove the oxide layer on the surface of silver ingots by turning, shape them into silver vapor-plated materials, and then use steel balls to grind away a small amount of oxide layer on the surface of the silver vapor-plated materials. After ultrasonic cleaning, the surface is obtained with an oxygen content of less than 10 ppm. This avoids the problem of silver liquid splashing caused by oxygen release during use and reduces material waste. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments.

[0028] Example 1:

[0029] S1. Casting: Electrolytic silver is put into a vacuum melting furnace, melted completely, and then cast into a smooth silver ingot.

[0030] Electrolytic silver is produced by reducing anions at the cathode through an electrolytic reaction. During this process, the silver adheres firmly to the cathode, necessitating a melting process to separate the cathode material from the silver before it can be cast into ingots. In this process, the molten silver is exposed to air, causing its surface to absorb some oxygen. Because solid silver has a face-centered cubic structure, the radius of a silver lattice vacancy is smaller than the radius of an oxygen atom. Therefore, oxygen atoms cannot penetrate the solid silver interior but instead adsorb onto the surface of the silver vapor-deposited material, forming an oxide layer covering the ingot's surface.

[0031] S2. Turning: Turn the surface of the silver ingot by 1mm to obtain the turned silver ingot.

[0032] Turning is a mechanical method to remove the oxide layer covering the surface of the silver ingot. It is not only simple to operate, but also effectively reduces the overall oxygen content of the silver ingot.

[0033] S3. Heat preservation: The machined silver ingot is kept in a vacuum environment at a temperature of 600°C for 0.5 hours to obtain a heat-preserved silver ingot.

[0034] The vacuum environment prevents oxygen from contacting the surface of the machined silver ingot, and the heat preservation temperature is always lower than the melting point of silver, resulting in a relatively uniform temperature distribution. However, it softens the silver, increases its plasticity and makes it more uniform, so that it can be formed into silver vapor-plated material in the next step.

[0035] S4. Forming: The heat-insulated silver ingot is extruded into wire of the designed diameter to obtain silver vapor-plated material.

[0036] The forming process mainly involves transforming large silver ingots into smaller structures that can be used during vapor deposition. Depending on the application, the shape of the silver vapor-deposited material can be fine lines.

[0037] S5. Steel ball grinding: Mix the silver vapor-plated material with stainless steel balls and add degreasing agent for grinding. The grinding time is 0.5 hours. Wash the grinding debris clean and sieve to obtain the ground silver vapor-plated material.

[0038] If the silver vapor-deposited material is an extruded wire, a certain thickness of oxide layer may be formed on the surface due to heat melting. At this time, the surface of the silver vapor-deposited material is no longer flat but curved. Therefore, small stainless steel balls can be used for grinding. The diameter of the stainless steel balls is preferably 2-10 mm; if they are too large, they are easy to damage the shape of the silver vapor-deposited material during grinding.

[0039] A degreasing agent, which is an aqueous solution containing a surfactant, can be added during the grinding of steel balls. The surfactant can dissolve some oily substances on the surface of the silver vapor-deposited material into water, making them easy to remove after sieving, thus preventing any impact on the purity of the silver vapor-deposited material.

[0040] S6. Ultrasonic cleaning: The ground silver vapor-deposited material is placed in an organic solvent and cleaned under an ultrasonic atmosphere for 60 minutes. After removal, it is added back to pure water and cleaned again under an ultrasonic atmosphere for 60 minutes to obtain the cleaned silver vapor-deposited material.

[0041] Organic solvents can dissolve residual organic impurities on the surface of silver vapor-deposited materials. With the assistance of ultrasound, organic solvents can penetrate into very small areas of the silver vapor-deposited material and dissolve the organic impurities. Acetone is preferred as the organic solvent because it has good volatility and is less likely to leave residues after cleaning.

[0042] S7. Dehydration and drying: Remove the moisture from the surface of the cleaned silver vapor-coated material to obtain a dry silver vapor-coated material (oxygen content 7.49ppm). The silver vapor-coated material is in the form of fine lines.

[0043] Example 2:

[0044] S1. Casting: Electrolytic silver is put into a vacuum melting furnace, melted completely, and then cast into a smooth silver ingot.

[0045] S2, Turning: Turn the surface of the silver ingot by 3mm to obtain the turned silver ingot;

[0046] S3. Heat preservation: The machined silver ingot is kept in a vacuum environment at a temperature of 700℃ for 2 hours to obtain a heat-preserved silver ingot.

[0047] S4. Molding: Granulate the heat-insulated silver ingots into particles of the designed particle size to obtain silver vapor-plated material;

[0048] S5. Steel ball grinding: Mix the silver vapor-plated material with stainless steel balls and add degreasing agent for grinding. The grinding time is 4 hours. Wash the grinding debris clean and sieve to obtain the ground silver vapor-plated material.

[0049] S6. Ultrasonic cleaning: Place the ground silver vapor-deposited material into an organic solvent and clean it under an ultrasonic atmosphere for 5 minutes. After taking it out, add it back into pure water and clean it again under an ultrasonic atmosphere for 5 minutes to obtain the cleaned silver vapor-deposited material.

[0050] S7. Dehydration and drying: Remove the moisture from the surface of the cleaned silver vapor-coated material to obtain a dry silver vapor-coated material (oxygen content 4.52ppm). The silver vapor-coated material is in the form of particles.

[0051] Example 3:

[0052] S1. Casting: Electrolytic silver is put into a vacuum melting furnace, melted completely, and then cast into a smooth silver ingot.

[0053] S2. Turning: Turn the surface of the silver ingot by 10mm to obtain the turned silver ingot;

[0054] S3. Heat preservation: The machined silver ingot is kept in a vacuum environment at a temperature of 900°C for 4 hours to obtain a heat-preserved silver ingot.

[0055] S4. Molding: After heat preservation, the silver ingot is hot-pressed into a sheet of the designed thickness and then cut into small pieces of the set size to obtain silver vapor-plated material.

[0056] S5. Steel ball grinding: Mix the silver vapor-plated material with stainless steel balls and add degreasing agent for grinding. The grinding time is 4 hours. Wash the grinding debris clean and sieve to obtain the ground silver vapor-plated material.

[0057] S6. Ultrasonic cleaning: The ground silver vapor-deposited material is placed in an organic solvent and cleaned under an ultrasonic atmosphere for 30 minutes. After being taken out, it is added back to pure water and cleaned again under an ultrasonic atmosphere for 30 minutes to obtain the cleaned silver vapor-deposited material.

[0058] S7. Dehydration and drying: Remove the moisture from the surface of the cleaned silver vapor-deposited material to obtain a dried silver vapor-deposited material (oxygen content 9.14ppm). The silver vapor-deposited material is in the form of a thin sheet.

[0059] The oxygen content of the silver vapor-deposited materials obtained in Examples 1-3 is all below 10ppm, which is superior to the silver vapor-deposited materials on the market. This effectively avoids the problem of silver liquid splashing caused by oxygen release during use and reduces material waste.

[0060] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for producing a low-oxygen-content silver evaporation material, characterized by the steps of: include: ​ S1. Casting: Electrolytic silver is melted until completely melted and then poured into a smooth silver ingot. S2. Turning: Turn the surface of the silver ingot by 1~10mm to obtain the turned silver ingot; S3. Heat preservation: The machined silver ingot is kept in a vacuum environment at a temperature of 600~900℃ for 0.5~4h to obtain a heat-preserved silver ingot. S4. Molding: The heat-insulated silver ingot is melted and shaped into the design size to obtain the silver vapor-plated material; S5. Steel ball grinding: The silver vapor-plated material is mixed with stainless steel balls and ground. The steel balls are stainless steel balls with a diameter of 2~10mm. An oil remover is added during the grinding process. The oil remover is an aqueous solution containing a surfactant. The grinding time is 0.5~4h. The grinding debris is washed clean and sieved to obtain the ground silver vapor-plated material. S6. Ultrasonic cleaning: Place the ground silver vapor-deposited material into an organic solvent and clean it under an ultrasonic atmosphere for 5-60 minutes. After taking it out, add it back into pure water and clean it again under an ultrasonic atmosphere for 5-60 minutes to obtain the cleaned silver vapor-deposited material. S7. Dehydration and drying: Remove the moisture from the surface of the cleaned silver vapor-plated material to obtain a dry silver vapor-plated material.

2. The method for producing a low-oxygen-content silver evaporated material according to claim 1, characterized by: The forming steps involve extruding silver ingots into wires of a designed diameter, granulating them into silver particles of a designed size, or hot-pressing them into sheets of a designed thickness and then cutting them into small pieces of a set size.

3. The method for preparing low-oxygen silver vapor-deposited material according to claim 1, characterized in that: The organic solvent is acetone.