Scope of Application: Compressed bulk PiG, printed PiGF ｜ Control Standard: Furnace temperature difference ≤3℃, Sintering oxygen content ≤10ppm, Powder vacuum drying: 150℃ for 6h
Process Red Line: Nitride/KSF phosphor prohibited from high-temperature air sintering; Direct dry mixing & compression molding is forbidden
| Defect Phenomenon | Root Cause | On-site Quick Solutions (Parameter Adjustment) |
|---|---|---|
| Internal bubbles, surface bulges, foggy & low light transmittance | Moist powder, entrapped air, no exhaust heat preservation | 1. Vacuum dry raw materials for 6h; 2. Vacuum defoam slurry for 30min; 3. Keep 500℃ for 30min under slight negative pressure for air exhaust |
| Finished crack, edge chipping, easy breakage during cutting | Fast heating/cooling rate, uneven green body density, no annealing treatment | Heating rate ≤3℃/min, cooling rate ≤5℃/min; Add 450℃ annealing for 60min; Stage compression with 60s pressure holding |
| Sheet curling, sintering collapse, undersized dimension | Excessive sintering temperature, long holding time, no supporting fixture | Reduce peak temperature by 10~20℃; Shorten high-temperature holding time; Full coverage support with alumina ceramic plate |
| Black spots, hard impurities, surface pits | Unsieved powder, zirconia tank debris, binder carbonization from incomplete degreasing | Sift powder via 800-mesh screen; Replace grinding tank liner regularly; Extend degreasing holding time at 350℃ |
| Overall devitrification, crystal ring, striped haze | Glass high-temperature crystallization, phosphor-glass interfacial reaction | Reduce furnace temperature by 20℃; Cut high-temperature holding time by half; Adopt coated phosphor preferentially |
| Defect Phenomenon | Root Cause | On-site Quick Solutions (Parameter Adjustment) |
|---|---|---|
| Large color difference on single piece/batch, excessive color coordinate drift | Powder segregation, uneven furnace temperature, fluctuating oxygen content | Wet mixing + powder granulation; Install homogenizing plate inside furnace; Stabilize furnace oxygen content ≤10ppm |
| Low luminous efficiency, missing red light, blackened phosphor | Nitride phosphor oxidation, high-temperature thermal degradation | Full-process sealed nitrogen sintering; Adopt low-temperature glass (sintering below 500℃); Eliminate furnace air leakage |
| Whitening & severe luminous decay after 85℃/85RH aging test | High alkali metal content of glass, ion migration | Replace low-alkali/alkali-free glass; Apply moisture-proof coating on finished products; Add annealing process |
| Uneven light spot & partial yellowing under high-power lighting | Phosphor agglomeration, poor thermal conductivity, interfacial scattering | Filter slurry to remove agglomerates; Add BN/alumina thermal conductive filler; Apply surface coating on phosphor |
| Defect Phenomenon | On-site Quick Solutions |
|---|---|
| Slurry delamination, up-down color difference, powder sedimentation | Add dispersant; Keep low-speed constant stirring before molding; Granulate powder after wet mixing |
| Powder falling off green body, low strength & easy damage in handling | Adjust binder dosage; Extend pressure holding time; Adopt quantitative powder feeding |
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