CMP Polishing Layer Microsphere Density Control

The patent applies preliminary action by classifying liquid-filled microspheres before they are expanded into foam microspheres. The centrifugal air classifier separates liquid-filled microspheres based on their density and size, removing impurities and dense regions (such as unreacted monomers and catalyst residues) before the expansion process. This preliminary classification ensures that only high-quality microspheres undergo expansion, preventing the formation of defects in the final foam structure.

The patent utilizes parameter changes by exploiting the density difference between liquid-filled microspheres and impurities during centrifugal classification. The classifier operates at controlled air flow rates and rotation speeds to optimize separation based on density parameters. After classification, the microspheres undergo expansion where the liquid filling evaporates or reacts, changing the density parameter again to create the final foam structure with improved uniformity.

The patent applies the taking out principle by removing inorganic particles and other impurities from the microsphere composition through centrifugal classification. The classifier extracts and separates these harmful inorganic stabilizing agents from the liquid-filled microspheres based on density differences. This extraction process eliminates the source of dense regions and impurities that would otherwise remain trapped in the microsphere structure after expansion.

The patent converts the potential harm of using inorganic stabilizing agents into a benefit by utilizing the density difference they create. The inorganic particles, while harmful if retained, provide a useful density contrast that enables effective separation through centrifugal classification. The harmful inorganic impurities are thus converted into a useful separation mechanism, allowing their removal and improving the final product quality.

The patent applies preliminary action by performing classification on liquid-filled microspheres before the expansion and curing processes. This timing ensures that the microspheres are classified in their stable liquid-filled state, before any secondary expansion can occur during curing. The classification is completed while the microsphere composition is still uniform and controllable, preventing later inconsistencies.

The patent segments the manufacturing process into distinct stages: (1) synthesis of liquid-filled microspheres, (2) centrifugal classification of liquid-filled microspheres, (3) expansion to foam microspheres, and (4) curing. By segmenting the process and performing classification at the liquid-filled stage, the patent avoids the problem of secondary expansion during curing affecting classification accuracy. Each stage is optimized independently, with classification occurring when microspheres are most stable and controllable.