Full-automatic ultrasonic cleaning technology for large-diameter optical parts before plating
At present, with the development of optical technology, the application fields of optical parts are more and more extensive, not only the corresponding optical manufacturing industry develops rapidly, but also the production batch is expanding to meet the needs of the market. The surface of optical parts is manually wiped before plating. The process has been unable to meet the requirements, and the pre-plating cleaning process on the surface of optical parts has encountered significant challenges. Therefore, the ultrasonic cleaning process of optical parts came into being. 2 The cleaning agent of optical glass ultrasonic cleaning The ultrasonic cleaning agent of optical glass has two categories: organic cleaning agent and inorganic cleaning. General organic cleaning agent (such as trichloroethylene carbon tetrachloride) Etc.) For the cleaning of the pre-process of optical parts processing, it is mainly for cleaning the protective layer of the polished surface of the workpiece; the inorganic cleaning agent is the cleaning of the post-processing of the cleaning of the workpiece, and the inorganic cleaning agent is generally a cleaning agent for the alkaline solution. These inorganic alkaline solutions are not a single component and are a mixture of various components (for example, a potassium hydroxide mixed solution, a sodium hydroxide mixed solution, etc.), but the alkalinity of the alkaline solution used is different due to the chemical stability of the glass material. The strength is not the same, so the solution used for the glass with poor chemical stability is weaker. On the contrary, the solution with good chemical stability is more alkaline. Due to the rapid development of optical manufacturing technology, there are many domestic and foreign manufacturers. In the production of special cleaning agents for optical glass, the composition of these cleaning agents is not single, but It is a mixed solution of many ingredients. There is a main component in the solution, the other components play an auxiliary role, such as the surfactant to increase the activity of cleaning the surface, the defoaming agent to eliminate the foam generated during the cleaning process, etc. The name of the current cleaning agent is called optical glass cleaning. Solution solution, only the grade of the solution is different. For example, a Japanese company: 2004-10-12 19 female i Chongqing Lushan people engineer 6 bachelor company has glass cleaner aqueous solution 55 glass cleaner aqueous solution 291; Switzerland a company has glass Ultrasonic cleaning of 3 optical parts such as cleaning agent deconexOP120deconexOP140 and deconexOP190 Ultrasonic cleaning is mainly composed of three parts: the energy of ultrasonic itself, the energy released by cavity blasting and the stirring effect of ultrasonic wave on the medium. The ultrasonic wave itself has a strong energy. When it propagates in the medium, it can transmit energy through the mass of the media to the surface of the cleaning object, causing the dirt to disperse and peel off. At the same time, during the propagation of the medium, the ultrasonic wave propagates forward in a way that the positive pressure and the negative pressure repeatedly alternate. When the negative pressure causes a tiny vacuum cave in the medium, the dissolved gas in the medium is quickly released into the vacuum. The cavity forms a cavity; when the positive pressure is pressed, the cavity is adiabatically compressed to explode, releasing huge energy, generating KfPa~KfPa pressure and local high temperature around the bubble, which is enough to shoot down the surface of the object to achieve the cleaning effect, which is called The effect of the cavitation effect on the agitation of the medium can promote the above two effects more evenly, accelerate the stripping of the dirt, and improve the cleaning efficiency. Ultrasonic cleaning used in the 1950s, with the maturity of the technology, ultrasonic cleaning It is widely used in aerospace industry cleaning engines, hydraulic and filtration systems; cleaning of silicon wafers, circuit boards, electrical components, etc. in the electronics industry. In the early 1990s, ultrasonic cleaning began to be applied to the cleaning of optical parts. The original ultrasonic cleaning technology for optical parts was not mature. It was only used for cleaning between processes and cleaning of polished parts of optical parts. Later, it gradually developed to the pre-plating of optical parts. Net cleaning, but mainly used for cleaning small and medium-sized parts. For optical parts with large caliber and thick central thickness, high-purity cleaning before plating has always been a problem. It is mainly automatic for such large and thick parts. Ultrasonic cleaning process is discussed.
3.1 Selection of process parameters Ultrasonic cleaning should achieve the best cleaning effect. Attention must be paid to the selection of the following process parameters. 3.1.1 Power selection The power selection is the main parameter of ultrasonic cleaning. The power is too small, the ultrasonic sound intensity is too small, and the cleaning is not achieved. The effect; the power is too large, which tends to cause pitting on the polished surface of the optical component and also reduces the life of the cleaning machine. The ultrasonic cleaning power is generally selected from 0.1 kW to 1.2. The ultrasonic cleaning frequency is generally selected between 20 kHz and 10 t kHz. Most of the cleaning agents currently used are water-based cleaning agents. When using water-based cleaning agents, the ultrasonic frequency is generally selected between 15 kHz and 30 kHz, because the cleaning requirements of optical parts are relatively high, and no pitting occurs on the surface of optical parts. Underneath, the ultrasonic frequency should be relatively high in the cleaning process, because the main purpose of cleaning the solvent and cleaning in each tank is different. To achieve a good cleaning effect, the ultrasonic frequency of each tank should be based on the corresponding solvent and cleaning. The purpose is to select the organic solution, the ultrasonic frequency can be selected higher. The solvent to start the cleaning tank is generally alkaline water-based solution. At the beginning, the surface of the workpiece is dirty, and the ultrasonic frequency is selected to be lower. Generally, 28 kHz is selected because the general frequency The lower the cavitation effect is, the more obvious the agitation of the cleaning solution is, the movement of the vehicle liquid is generated, and the energy released by the hole blasting is larger, which is beneficial to remove and dissolve the dirt on the surface of the workpiece; with the cleanliness of the surface of the workpiece Improve, the solvent in the back cleaning tank is generally a dehydrating agent for organic solvents, and the ultrasonic frequency is selected to be higher. Generally, 100 kHz is selected, because the higher the frequency, the higher the cleaning density, the higher the cleaning cleanliness, which is beneficial to remove the tiny dirt on the surface, and further improve the cleanliness of the surface of the workpiece. 3.1.3 Temperature Selection The temperature of the cleaning solution is higher for ultrasonic cleaning. Large shadows Each medium has an optimum temperature, the cavitation active temperature. Temperatures that are too high or too low can have an effect on cavitation. For example, the active temperature of water-based medium cavitation is 60*C, so it is more suitable to use 60*C water as the cleaning solution; if the solution is an organic solvent, not only the cavitation active temperature but also the organic solvent is high. Therefore, the solvent is used at a lower temperature, generally about 15C organic solvent is more suitable. 3.2 Cleaning product selection 3.2.1 Cleaning agent selection According to the optical component processing technology, the type of workpiece surface attachment is determined, and then the removal of various attachments is determined. If it is the preparation process of the disk forming process, the first choice is to protect the surface of the workpiece. The cleaning agent is for other attachments on the surface of the workpiece, and it is used to spread the light dust and fingerprints and other processing attachments. The first step is to remove the protective paint; if it is a single-piece process, it is not necessary to consider the protective paint to remove the surface of the workpiece, directly considering the cleaning agent selected for the surface of the workpiece, polishing dust, fingerprints and other processing attachments are now optical The surface cleanliness requirements of parts are getting higher and higher, and some important cleaning agents are based on the materials and surfaces of the cleaned optical parts. Specific cleanliness requirements with ultrasonic cleaning agents themselves Shu optical component is generally more alkaline solution.
3.2.2 Selection of dehydrating agent With the emphasis on environmental protection in the society, dehydrating agents that have been used for a long time to prove good dehydration effect are being included in the scope of prohibition due to the impact on the ecological environment, such as: Freon. Now I have found some new dehydrating agents, such as: 141BIPA and other new dehydrating agents, should choose the appropriate dehydrating agent according to the quality requirements of the cleaned workpiece.
3.2.3 Selection of filter core According to the degree of cleanness of the surface of the workpiece during the cleaning process, the accuracy of the filter core of each tank filtration system is different, but the general rule is that the filter core of the front cleaning tank has low precision and is closer to the dewatering tank. The higher the accuracy of the filter core for the groove, the lower the filter capacity of the first and second grooves is 5 less. The accuracy of the rear filter core is determined according to the quality requirements of the entire cleaning workpiece. Generally, it is stepwisely improved, and the filter wick currently used is the highest. The accuracy is: Fm. In order to improve the precision of the filtration system, it is necessary to select the filter core of other materials. The accuracy of the filter core of other materials can reach the influence of Q. The ultrasonic cleaning effect is in addition to the above main factors, but also pay attention to the medium liquid flow cleaning. The influence of factors such as the location of the object. Generally speaking, during the cleaning process, the level of the cleaning solution should be at least 100 mm above the surface of the vibrating sub-surface, and the flow rate of the cleaning solution is not too fast, preferably flowing, and the cleaning parts can be moved up and down in the cleaning solution to achieve optimal cleaning. effect.
3.3 Process Flow The process of pre-plating cleaning of optical parts is roughly divided into three stages: lotion cleaning pure water bleaching water agent dehydration. The following is a single piece plus 180mm center thickness 23mm large diameter optical lens as an example to introduce the automatic super-plating before plating. Net cleaning process: automatic feeding * (1) washing agent ultrasonic cleaning * (2) pure water overflow ultrasonic cleaning * (3) washing agent ultrasonic cleaning * (4) ultra-pure water ultrasonic washing * (5) ultra-pure water Ultrasonic rinsing*(6) Ultrapure water ultrasonic rinsing*(7) Ultrapure water rinsing*(8)IPA ultrasonic dehydration*(9)IPA dehydration*(10)IPA ultrasonic dehydration*(11)IPA dehydration*(12) slow Pulling and thawing - automatic feeding according to the cleanliness requirements of the cleaned lens surface: (1) The cleaning solution for the first tank is a self-made alkaline water-based solution, and the cleaning solution for the third tank is an alkaline water imported from Japan. The solution prepared by the base cleaning agent; (2) the analytically pure IPA is used as the dehydrating agent; (3) the precision of the filter core for the 8~11 tank filtration system is gradually increased; (4) the 12 tank is the IPA steam cleaning 4 conclusion Using this ultrasonic cleaning process for more than a year Production practice, the cleaning quality of the workpiece is relatively stable, the pass rate is generally 85%. The results show that the automatic ultrasonic cleaning process is relatively good in both the cleaning quality and the cleaning quantity. There is a significant improvement, while also greatly reducing manpower, reducing the impact of human factors on the cleanliness of the lens surface, reducing the artificial scratch on the surface of the workpiece.
According to relevant information, a high-frequency ultrasonic cleaning has been developed abroad, with a frequency of up to 700 kHz to 1 MHz, which can remove 1 um of dirt, which is very beneficial for improving the cleanliness of the vapor-deposited surface of optical parts; A new type of super-vibration cleaning technology, which can be cleaned by 50Hz frequency vibration. This kind of cleaning has less damage to the cleaning object and can be applied to the cleaning of fragile and vulnerable surfaces. It is very beneficial to the cleaning of optical parts with very soft materials such as ZF13. Not only is it very soft, but its chemical stability is poor. With the development of ultrasonic cleaning technology, there is hope for ultrasonic cleaning of parts of this optical material.
Reliability: extremely stable
Fast drying: higher boiling point, completely volatile
Renewability: Reducing the amount of industrial waste by distillation
Permeability: low viscosity, low surface tension, high density, high fluidity
Safety: no flash point, non-flammable liquid, easier to set up
Environmentally friendly: It does not consume ozone and easily passes various environmental standards.
Due to its high stability, in addition to the strong alkali strong acid strong reducing agent, the general materials are suitable; for the sake of safety, it is recommended that the user first make compatibility test and overall evaluation before applying to production.
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