The Detail Study on the Effect of the Flow During The Curing Process of phosphor Particles on the Color Performance

Abstract

The correlated color temperature (CCT) shift after the polymer curing process is a very common phenomenon in Light Emitting Diodes (LEDs) packaging. During the curing process, the particles in LED encapsulant will flow with the fluid due to the nonuniform heating inside the polymer. Then, the polymer and the phosphor particles will solidify very quickly when the cross-linking reaction is trigged. In order to investigate the difference of the phosphor positions before and after the curing, in this work, a finite element analysis (FEA) simulation was carried out to simulate the flow of the polymer that contained the phosphors. The light color performance was subsequently simulated by finite-difference time-domain (FDTD) and Ray tracing (RT) combined method. As the result shows, the flow of LED encapsulant with phosphor particles can change the concentration of phosphor in different layers of LED encapsulant. Such changes can cause redshift and blueshift of transmitted light. Finally, new structure encapsulation cups were proposed to inhibit the flow of LED encapsulant with phosphor particles. The results shows that the serrated encapsulation cup can effectively inhibit the change of concentration during LED encapsulant curing.