How well the pvd coating machine cleans the workpieces before plating them is directly related to the yield rate of the later coated workpieces. If the cleaning process is done well, the rate of defective products will be greatly reduced, which improves work efficiency and saves costs, because when purchasing vacuum In front of the coating machine, everyone pays great attention to the cleaning process. What is the cleaning process before plating the workpiece? Below, the editor of Huicheng Vacuum will introduce it to you, hoping to help you:

Cleaning is to remove oil, rust, dust, etc. from the workpiece through chemical or (and) physical methods to ensure that the workpiece obtains better coating adhesion and smooth production. Cleaning is an essential process before PVD coating, and it is also the most important process in PVD coating production. If there is a problem with cleaning, the coating production will have to be delayed, the coating process may be interrupted, or there may be problems with the coating bonding force. Leading to customer complaints and compensation, especially when the technical capabilities of the coating equipment are not high, cleaning problems are more likely to occur, and the above risks are more likely to occur.
There are four factors that affect the quality of cleaning, namely: cleaning time, chemicals, mechanical action and cleaning fluid temperature. These four factors also influence each other. The weakening of one factor can be enhanced by enhancing the effects of the other three factors. to compensate and vice versa. Among these four factors, minimizing cleaning time is also the goal pursued, which can improve cleaning efficiency. Reduce production time and delivery cycle.
The main cleaning methods and steps should include: chemical spraying, chemical soaking and ultrasonic cleaning, rinsing, and drying.
1) Chemical spray
Spraying is very effective for cleaning. It can remove most oil stains and contaminants from the workpiece. Especially for workpieces with holes, it is more effective. The chemicals sprayed on the workpiece will flow into the holes or the chemicals will be sprayed directly into the holes to flush the inner walls of the holes. Therefore, when cleaning and installing the card, the workpiece must be sprayed. In addition, if the chemicals sprayed on the workpiece cannot flow away immediately, it will prevent the fresh chemicals from continuing to clean the workpiece, and it will not be easy to dry in the subsequent drying steps. Therefore, when installing the card, ensure that it flows to the workpiece. The medicine on it can flow away naturally.
2) Chemical soaking and ultrasonic cleaning
Ultrasound is a sound wave with a frequency above 20 kHz beyond the human hearing range. The propagation of ultrasonic waves relies on elastic media. When it propagates, it causes the particles in the elastic medium to oscillate and transfers energy through the medium in the propagation direction of the ultrasonic waves. This wave can be divided into longitudinal waves and transverse waves. In solids, both can be transmitted, while in gases and liquids, only longitudinal waves can be transmitted. Ultrasonic waves can cause particle vibration, and the acceleration of particle vibration is proportional to the square of the ultrasonic frequency. Therefore, ultrasound of tens of kilohertz will produce a huge force. When strong ultrasonic waves propagate in liquids, acoustic cavitation will occur due to nonlinear effects. The shock wave emitted when the cavitation bubble suddenly closes can generate thousands of atmospheric pressures around it, directly and repeatedly impacting the dirt layer. On the one hand, it destroys the adsorption of dirt and the surface of the cleaning parts, and on the other hand, it also causes the dirt layer to form. They break away from the surface of the cleaning parts and disperse them into the cleaning fluid. The vibration of the bubbles can also scrub solid surfaces. The bubbles can also "drill" into cracks and vibrate, causing dirt to fall off. For greasy dirt, due to ultrasonic cavitation, the two liquids quickly disperse and emulsify at the interface. When the solid particles are wrapped in oil and adhere to the surface of the cleaning piece, the oil is emulsified and the solid particles fall off. During the vibration process, cavitation bubbles will cause circulation in the liquid itself, which is the so-called acoustic flow. It can cause a high velocity gradient and viscous stress on the surface of the vibrating bubbles, promoting the destruction and shedding of dirt on the surface of the cleaning parts. The high-speed microjet generated by ultrasonic cavitation on the solid and liquid surfaces can remove or weaken the boundary dirt layer. , corrodes the solid surface, increases the stirring effect, accelerates the dissolution of soluble dirt, and strengthens the cleaning effect of chemical cleaning agents. In addition, ultrasonic vibration causes large vibration speeds and accelerations of particles in the cleaning fluid, which also causes the dirt on the surface of the cleaning parts to be subject to frequent and violent impacts.
Because ultrasonic waves will produce low-pressure areas and high-pressure areas during the transmission process, and cavitation only occurs in the low-pressure area. Therefore, the workpiece to be cleaned needs to vibrate up and down in the ultrasonic wave, so that every area on the workpiece passes through the low-pressure area to obtain the cleaning effect of the "micro brush". The transmission speed of ultrasonic waves in water is 1500m/s. Assuming that the frequency of ultrasonic waves is 30000Hz, the wavelength of ultrasonic waves used is λ=speed/frequency=1500/30000=0.05m=5cm
Therefore, if 30000Hz ultrasonic wave is used, the up and down vibration distance of the workpiece should not be less than 5 cm. For ultrasonic waves of other frequencies. The vibration distance can be calculated similarly. In pure chemical immersion cleaning, the cleaning solution first dissolves the contaminants on the surface of the workpiece, and gradually penetrates and dissolves into the contamination layer. In this process, a dissolved saturated layer will gradually form on the surface of the workpiece. This saturated layer isolates the fresh chemical cleaning solution from the deep-seated contaminants, preventing the cleaning solution from continuing to dissolve the deep-seated contaminants. If this saturated layer cannot be destroyed and removed, cleaning will stop. For dirty workpieces, it is difficult to completely clean the workpieces by pure immersion cleaning. The "micro brush" of ultrasonic waves can destroy the dissolved saturated layer on the surface. New chemicals reach the deeper pollution layer and continue to dissolve. The ultrasonic waves then continue to destroy the newly formed dissolved saturated layer. In this cycle, cleaning continues. Go on until the work piece is clean.
3) Rinse
Rinsing is to thoroughly remove cleaning fluid or other dirt remaining on the workpiece so that the workpiece is cleaner before drying. Residues on the workpiece will be difficult to clean after drying. In the industrial field. Deionized water is usually used for rinsing, and deionized water is used instead of tap water for rinsing. It can prevent impurities and pollutants in tap water from remaining on the workpiece. However, deionized water is highly corrosive and can cause corrosion to the workpiece. Therefore, a certain amount of anti-rust agent must be added to deionized water before it can be used to rinse workpieces. To prevent the workpiece from being rusted during the rinsing and drying process.
4) Drying
The cleaned workpieces are generally placed in an oven for drying. The oven includes a box, drainage pipeline, heating system, exhaust system and temperature control system. The boiling and vaporizing temperature of water is 100°C, so the baking temperature must be greater than 100°C, preferably between 110°C and 130°C, so that the water can be quickly evaporated to dry the workpiece. After drying, the temperature of the workpiece will not be too high and it will take a long time to cool down.
Before plating workpieces with a pvd coating machine, strict cleaning steps must be arranged. Only by cleaning the workpieces cleanly can the yield rate of the later workpieces be ensured.