Core Mass-Production Issues and Comprehensive Mitigation Strategies for PiG (Phosphor in Glass) (Item 3)

Excessively high sintering temperature, prolonged high-temperature holding time or poor thermal stability of glass formula will trigger spontaneous precipitation of borate and silicate crystals inside the glass matrix, resulting in white haze and striae. These defects greatly reduce light transmittance, cause severe light scattering and uneven light spots on LED light sources.

Phosphor particles act as crystal nucleation sites, triggering massive devitrification of glass along particle surfaces. This intensifies interfacial light scattering, cuts down luminous efficiency and leads to inconsistent correlated color temperature.

Failure to sieve powder raw materials, alumina/zirconia contaminants abraded from milling tanks, and graphite debris falling from molds into green bodies will form hard black inclusion stones, rendering PiG products directly scrapped.

Adjust the ratio of borosilicate or tellurite components, and add a small amount of Al₂O₃ and La₂O₃ to restrain crystal nucleus growth. Develop glass with a narrow softening temperature range to avoid long-term dwelling within the devitrification temperature window.

Control furnace temperature tolerance within ±5°C and shorten high-temperature holding duration. Adopt rapid heating and cooling cycles to minimize residence time in the devitrification zone. Deploy infrared rapid sintering to bypass temperature ranges prone to crystal precipitation.

Sieve all glass powder and phosphor powder through 300–800 mesh screens. Use high-purity zirconia lining and zirconia grinding balls for ball milling. Apply uniform graphite coating on sintering molds and regularly remove dust residues inside furnace chambers. Complete all green body transfer procedures in a dust-free workshop.