In the ultra-thin wafer grinding or thinning process, porous ceramic vacuum chucks are often used to achieve flat fixation and clamping of wafers. Coolant or clean water is also used in the grinding process. Since the wafer cannot cover the entire adsorption area of ??the porous vacuum chuck, some coolant or clean water will be quickly sucked into the porous ceramic vacuum chuck. If the sucked liquid is not separated, it will be transported to the inside of the vacuum pump, thereby damaging the vacuum pump. The vacuum pump cannot work properly. Therefore, we need a device that can automatically separate the liquid sucked into the porous ceramic vacuum chuck. Generally, the automatic vacuum liquid separator (model: CS-SM-220) is the best choice.
In actual use, we found some problems. The vacuum flow rate inside the porous vacuum chucks is relatively large, and the high flow rate of air will affect the separation effect of the automatic vacuum liquid separator. This is mainly because the high flow rate of air causes the liquid to atomize and vibrate. The CS-SM-220 automatic vacuum liquid separator is based on the principle of gravity to achieve the separation of vacuum air and liquid. The rapid flow of vacuum air causes the liquid to have no chance to settle and is directly transported to the hose connected to the vacuum pump. As a result, some liquids cannot be effectively separated, and the liquid separation effect is poor.
However, this is not an unsolvable problem. Our solution is to connect air tank to the main line to create a larger space so that the liquid and vacuum air can be fully separated. Let the liquid be collected at the bottom of the air tank, and connect the CS-SM-220 automatic vacuum liquid separator to the drainage outlet at the bottom of the air tank. This ensures that the liquid can settle thoroughly without limiting the inner diameter of the main line.
The specific equipment connection method is as shown in the figure below:
Since the inner diameter of the main line has not become smaller, the vacuum flow required by the porous vacuum chucks is not limited, ensuring the clamping force of the porous ceramic vacuum chucks. At the same time, the CS-SM-220 automatic vacuum liquid separator will not lose vacuum during the separation of liquid. This ensures the stable and constant clamping force of the porous vacuum chucks from two aspects. Since the CS-SM-220 automatic vacuum liquid separator can automatically separate liquid, there is no need to stop the machine to discharge liquid during the entire process of grinding the wafer.
However, there is a requirement for the combined use of this air storage tank and the CS-SM-220 automatic vacuum liquid separator. The height of the air storage tank must be higher than the automatic vacuum liquid separator, and the inner diameter of the hose of the main line must be larger than the inner diameter of the branch line connected to the automatic vacuum liquid separator. In this way, two hoses are connected in parallel, and the pipelines with large and small inner diameters are divided. It can achieve more vacuum air passing through the main line and less vacuum air passing through the branch line. It is recommended that the air storage tank should be no less than 10L. The above two requirements are guaranteed. It can achieve full automatic separation of liquid in high-flow vacuum air. If you have any questions, please send an email to communicate.
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