Core Mass-Production Issues and Comprehensive Mitigation Strategies for PiG (Phosphor in Glass) (Item 4)

There is a large disparity in density and particle size between glass powder and phosphor powder. Delamination occurs during dry blending, material transportation and compaction, resulting in local over-concentration or insufficient phosphor loading. This causes prominent correlated color temperature differences across a single PiG chip and excessive batch-to-batch color deviation.

Uneven furnace temperature, fluctuating oxygen levels in the protective atmosphere and inconsistent holding duration lead to varying degrees of phosphor degradation. The same batch of products suffers obvious shifts in CIE x/y coordinates and unstable color rendering index (CRI).

Thickness deviation of green bodies and inconsistent sintering shrinkage lead to variable blue light absorption, resulting in wide dispersion of color temperature among mass-produced parts.

Adopt wet ball milling matched with low-melting organic ester dispersants to achieve nano-level homogeneous dispersion. Perform mild granulation after drying to suppress delamination caused by density mismatch. Direct compression after dry mixing is prohibited.

Implement zoned temperature control inside the furnace and equip soaking plates to ensure the temperature difference across green bodies is less than 3°C. Maintain consistent loading capacity and placement spacing for batch sintering; stabilize oxygen content in inert atmosphere below 10 ppm.

Fabricate molds with high precision and apply unified compaction pressure. Calibrate sintering shrinkage curves in advance to compensate green body thickness. Classify finished products via laser thickness measurement, limiting thickness tolerance within ±5 μm.

Take standard test samples from each furnace batch for integrating sphere testing. Fine-tune sintering temperature and holding time in reverse adjustment to lock color coordinates within the target range.