Core Mass-Production Issues and Comprehensive Mitigation Strategies for PiG (Phosphor in Glass) (Item 6)

The thermal conductivity of pure PiG glass matrix only ranges from 0.8 to 1.5 W/mK. Under laser lighting power density above 1 W/mm², heat cannot dissipate efficiently, triggering phosphor thermal quenching and rapid luminous flux attenuation.

For high-alkali glass exposed to long-term 85°C/85%RH damp-heat conditions, alkali ions migrate to the material surface and corrode nitride phosphors. This results in severe luminous decay, color coordinate drift and surface whitening defects.

Mismatched thermal expansion coefficients between glass and phosphor particles create micro-gaps at the interface after thermal cycling, simultaneously reducing both light transmittance and overall thermal conduction performance.

Add trace nano-scale Al₂O₃ and BN thermal conductive fillers into the glass formulation to raise thermal conductivity to 3–8 W/mK and boost laser power resistance threshold. Assemble PiG components bonded with high-conductivity sapphire or aluminum substrates for practical application.

Eliminate high-lithium and high-sodium compositions, and adopt glass formulations based on alkaline earth metal oxides. Add a low-temperature annealing procedure post sintering to release internal residual stress and restrain alkali ion migration.

Fine-tune glass compositions to adjust refractive index and thermal expansion coefficients, narrowing the property gap between glass matrix and YAG / nitride phosphors, so no interfacial microcracks generate after repeated thermal cycling.