Light-emitting diodes （LEDs） have advantages in small size, light weight and, energy saving. They are usedfor portable device, backlight sources for TVs, light sources for illumination by practical application of white LEDs. Polyamide （PA） resin molding compounds are mainly used from the viewpoint of initial reflectivityand mechanical toughness for the LED reflectors. However, there is a problem that the light emissionintensity and luminance of the LED are lowered. The reason may be discoloration of PA in the reflector dueto heat and light, discoloration of impurities and low molecular weight oligomers in the resins, oxidation ofadditives （antioxidant, plasticizer, oligomer, etc.） by heat and light. PA resins are unavoidable in the formationof pyrrole ring compounds in thermal degradation （in the presence of oxygen ） and in the formation ofcompounds having aldehyde and amino groups in photodegradation. It is known that they form conjugateddouble bonds to absorb visible light, resulting in color change. It is said that PA resins containing amide grouphave fundamental issue, because higher heat resistance and light resistance are emphasized by increasing thebrightness of LEDs in the future.Therefore, we focus on thermosetting polyester （UP）, which is characterized by （Ⅰ） free from amidegroup, （Ⅱ） achievement with outdoor paint, （Ⅲ）high degree of freedom of combining polyhydric alcoholand polybasic acid. We have developed UP molding compounds having high reflectivity and high whiteness.We have reported that the light fastness of materials is improved by incorporating cyclohexyl ring into thebackbone of UP. In this manuscript, we report on the modeling of light source distance dependency of materialdeterioration, trial for manufacturing and evaluation of small actual model package, which is the current trendusing the developed UP materials.The developed UP molding materials have found overwhelming performance and high reliability byevaluation of side view type PKG compared with PA molding materials.
