PET silver-plated film uses chemical silver plating to prepare a silver film with a thickness of 150 μm on the PET film.
PET silver-plated film is an electronic component packaging technology based on PET film. It has the advantages of high temperature resistance, corrosion resistance, small size, and light weight. It is widely used in the packaging of consumer electronic products.
PET silver-plated film uses chemical silver plating to prepare a silver film with a thickness of 150 μm on the PET film. The silver plating process and chemical silver plating process were studied, and the silver-plated film was tested. The thickness, composition, antistatic properties, barrier properties and heat resistance of the silver-plated film layer were studied. The results show that: the dipping method is used for electroplating silver, and the thickness of the silver layer is about 120 μm; the chemical silver plating method uses a silver plating liquid and a silver plating process, and the thickness of the coating is 150 μm in a vacuum environment. After heat treatment at 400°C for 3 hours, the silver film It has good heat resistance and antistatic properties; for PET silver-plated films, its barrier properties, barrier rate and mechanical properties increase with the increase of film thickness; when the thickness of the coating layer reaches 300μm, the silver film and PET The adhesion between the films will be significantly reduced, and the mechanical adhesion between the silver layer and the PET film will also be significantly reduced. The silver-plated film still has excellent mechanical properties, and its elongation at break, tensile strength and flexural strength are significantly higher than those of the non-silver-plated film. Therefore, PET silver-plated films prepared by chemical silver plating technology have good application prospects.
PET has excellent mechanical properties, is resistant to chemical corrosion, and is widely used in many aspects. However, PET itself has poor light transmittance and thermal stability, and it is easy to produce photochromism under light, heat or moisture conditions. Since PET material itself has excellent mechanical properties, people began to surface modify it and plate it with various metal alloys, metal oxides and other materials on its surface for processing.
At present, the most widely used silver plating process is a silver film prepared by chemical plating, and a metal or alloy film is deposited on the surface. The silver plating process has high production efficiency and low cost because the deposition and plating of the silver layer are relatively easy to automate. Therefore, the electroless silver plating method is widely used in the preparation of various thin film materials.
It is generally believed that the silver-plated film has better mechanical properties, barrier properties, thermal stability and other characteristics. However, for applications in some special fields, due to limitations in cost, processing conditions, etc., the chemical silver plating method cannot be widely used to prepare silver-plated films.
This article uses chemical silver plating to deposit a silver film with a thickness of 150 μm on the PET film. The thickness, composition, and mechanical properties of the silver film are tested and analyzed to provide insights into the application of PET silver films in the field of optical devices. Application provides a theoretical basis.
Silver plating process
(1) Cleaning: Use acetone or chloroform to remove dust, oil and metal surface oxides on the film. Use acetone to clean the film on the glass surface, and use ammonia to clean the oil film on the surface.
(2) Activation is a key step in chemical silver plating. First, disperse the silver paste in sulfuric acid, then mix it evenly with the active agent, then add a small amount of surfactant and additives, stir evenly, and then immerse the solution on the surface of the PET film. The immersion time should be controlled between 2 and 4 minutes. If the time is too long, a gap will easily form between the silver paste and the PET film. If the immersion time is too short, the silver paste cannot be dispersed on the surface of the film, and the film layer will easily fall off.
(3) Activation is to vacuum-dry the impregnated PET film under a certain temperature and pressure. There are many vacuum drying methods used, including normal pressure drying and pressure drying; vacuum drying is to vacuum dry the impregnated film at 400~500°C.
(4) Electroless silver plating: After the silver paste and catalyst are fully mixed, the film is immersed in the silver paste, so that the silver paste in the solution is adsorbed on the film. When the temperature reaches 150°C (heating time is about 2 minutes), the film surface deposits An even layer of silver. Then place the film at 250~300°C for 1 minute to allow the film to cool to room temperature naturally.
(5) Silver plating: Use acetone or chloroform on the surface of the plated silver film to remove the remaining acetone and chloroform in the film layer, then clean it with ammonia water, and finally dry it at a certain temperature or naturally dry it. The suitable temperature for chemical silver plating is 15~30℃. If the temperature is lower than 15℃, the silver wire will fall off.
Silver plating pre-treatment
The dipping method is used for electroplating silver. The main salt content in the plating solution is 12g/L, the reducing agent dosage is 15g/L, the complexing agent dosage is 30g/L, and the temperature is 80°C. In order to increase the deposition speed of silver, improve the adhesion between the coating layer and the substrate, and improve the corrosion resistance of the silver film, the PET film was pickled in this study. The test results show that: for the electroplating silver process using the dipping method, the thickness of the silver layer is about 120 μm, and the adhesion between the silver layer and the PET film is poor; while for the process method using chemical silver plating, the thickness of the coating can reach about 150 μm. , the adhesion between the silver layer and the PET film is better.
When using the chemical silver plating process to prepare PET silver-plated films, the diffusion rate of silver ions is affected by factors such as the pre-plating treatment method and the concentration of the reducing agent in the plating solution. In this study, the dipping method was used for electroplating silver. Transfer the silver-plated PET film to a glass slide, add 5g/L hydroxylamine hydrochloride (HCl), 20g/L boric acid (BHBA) and 15g/L copper sulfate solution, stir at room temperature for 5 minutes, then remove the glass slide and Soak in boiling water for about 10 minutes. Through X-ray diffractometer (XRD) detection and scanning electron microscope (SEM) observation and analysis, it was found that the amount of silver nitrate precipitation was small, and the silver layer was dense and uniform.
Silver plating process
(1) The PET film to be silvered is pretreated at 60~80°C, and the metal elements on the film layer are reduced through the oxidation-reduction reaction in the air, thereby forming a silver film.
(2) Place the pretreated PET film on the chemical silver plating workbench containing the silver plating solution, and use a vacuum pump to evacuate the silver plating solution so that it is in a vacuum environment and reacts at a lower temperature.
(3) Silver will be consumed during the reaction. When the film thickness reaches 150 μm, the bonding force between the silver film and the PET film is no longer strong. At this time, after the silver plating workbench is evacuated to a vacuum, the current adjustment device of the chemical silver plating machine is used to adjust the concentration of silver ions in the plating solution so that it meets the process requirements. Then the current regulating device of the chemical silver plating machine is fixed, and the silver plating workbench is evacuated to a vacuum state again, so that it can react in a higher vacuum environment.
(4) When the coating thickness reaches 100μm, use a vacuum pump to evacuate the chemical silver plating machine to reduce the silver ion concentration in the plating solution to less than 10μg/ml. It is then heat treated to achieve the bonding force between the silver plating layer and the PET film.
Precautions
1. Chemical silver plating is a chemical raw material, and it is strictly prohibited to use organic solvents such as alcohol and acetone to clean the equipment.
2. Avoid splashing water during operation.
3. It is strictly forbidden to pour the silver plating solution into other solutions to prevent the silver plating solution from deteriorating.
4. If other substances need to be added to the silver liquid for some reason, check whether the silver liquid has deteriorated in advance.
5. Preparation of silver solution: Use 50g/L of pure water and 50g/L of deionized water, mix the two in a ratio of 5:1, filter, and store the resulting solution at room temperature for more than half a year.
6. Keep the equipment dry and dry the silver-plated plates. The drying temperature is about 80°C and the drying time is 1-2 hours.
7. The grounding of the equipment must be checked before electroplating. If there is no grounding, the resistance value should be measured with a resistance tester. It should be above 4 ohms (i.e. 5-10Ω); it can be used only after checking that there are no problems.
8. The equipment after silver plating must be vacuum tested to ensure that the vacuum degree meets the usage requirements before it can be started up and run; use dry compressed air to purge the vacuum pump inlet pipe to make the pressure in the pipe reach 0.07 MPa.
Conclusion
1. The silver plating process brings huge development space for the application of PET films, but the impact on the composition, antistatic performance and barrier properties of the silver layer requires further research.
2. The silver plating solution contains a certain proportion of organic solvents, and the gas generated by its volatilization can easily cause the organic components in the silver plating layer to dissolve, and the silver-plated film may become discolored. Therefore, the content of organic solvents in the silver plating solution should be controlled, and the deposition concentration of other components in the silver plating solution on the surface of the PET film should be increased as much as possible.
3. The barrier properties, barrier rate and mechanical properties of PET silver-plated film increase with the increase of coating thickness. When the thickness of the coating layer is 150 μm, its barrier properties, barrier rate and mechanical properties [sensitive words]; when the thickness of the coating layer reaches 300 μm, the adhesion between the silver film and the PET film is significantly reduced, and the gap between the silver layer and the PET film is The mechanical adhesion is also significantly reduced, so the mechanical properties of the silver-plated film are no longer better than those of the unsilvered film.
4. The electroless silver plating method has certain limitations: firstly, the thickness of the coating layer is difficult to control, and secondly, the process is complex and costly. Therefore, chemical silver plating technology needs further development. Using electrochemical deposition or sol-gel method to prepare PET silver-plated film can obtain a PET silver-plated film with uniform thickness, controllable thickness, good heat resistance and stable performance, and can be widely used in electronics, optics and thin films. materials and other fields.
