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LED encapsulation 실리콘의 기포잔류방지를 위한 step 경화공정 연구
송민재(M.J.Song),김흥규(H.K.Kim),윤길상(G.S.Yoon),김권희(K.H.Kim) 한국소성가공학회 2011 금형가공 심포지엄 Vol.2011 No.9
Generally, rapid cure reaction of LED encapsulation silicone resin causes serious defects in a cured resin product such as warpage, residual bubbles, and decreasing wetablility. In order to prevent residual bubbles in a silicone resin, step cure process was examined in the present paper. Three kinds of step cure processes were applied and bubble free phenomenon was observed experimentally. Experimental results showed that most of bubbles were removed under 70˚C which is the minimum temperature for activating cure reaction. In addition, degree of cure(DOC) and temperature distribution were predicted by using FEM analysis of heat transfer. It was concluded that maintaining cure temperature for providing DOC of less than 0.5~0.6 is an effective way to reduce residual bubbles and stress.
경화속도에 따른 LED encapsulation silicone 탄성 및 점탄성 warpage
송민재(M. J. Song),김흥규(H. K. Kim),윤길상(G S. Yoon),김권희(K. H. Kim) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
The effect of cure reaction rate on the warpage of silicone resin for LED encapsulation was examined by using FEM based on elastic as well as viscoelastic material model. A square plate-shaped specimen was assumed for analysis. Two different conditions of cure reaction rates, i.e a fast isothermal curing and a slow heat-up curing, were assumed for FEM. The FEM predictions were compared with the actual specimens from a curing experiment. The FEM predictions showed that the amount of warpage was larger in the fast isothermal curing process than the slow heat-up curing process. The increased warpage in case of the fast curing was supposed to be caused by the higher reaction heat and the accompanying increase of thermal expansion difference between silicone resin and lead frame. The FEM prediction of cooling process was obtained by using both elastic and viscoelastic material models. In comparison with the experiment, total warpage from the viscoelastic model was more similar to the experimental measurement than the elastic model.
LED encapsulation 실리콘의 step 경화공정 연구
송민재(M. J. Song),김흥규(H. K. Kim),윤길상(G. S. Yoon),김권희(K. H. Kim) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.10
Generally, rapid cure reaction of LED encapsulation silicon resin causes serious defects in a cured resin product such as warpage, residual bubbles, and decreasing wetability. In order to prevent residual bubbles in a silicone resin, step cure process was examined in the present paper. Three kinds of step cure processes were removed under 70℃ which is the minimum temperature for activating cure reaction. In addition, degree of cure(DOC) and temperature distribution were predicted by using FEM analysis of heat transfer. It was concluded the maintaining cure temperature for providing DOC of less than 0.5~0.6 is an effective way to reduce residual bubbles and stress.
승온 경화반응속도식을 이용한 LED용 실리콘 렌즈의 유한요소해석
송민재(M. J. Song),홍석관(S. K. Hong),박정연(J. Y. Park),이정원(J. W. Lee),윤길상(G. S. Yoon) 한국소성가공학회 2014 금형가공 심포지엄 Vol.2014 No.8
Silicone is recently used for LED chip lense due to its good thermal stability and optical transmittance. In order to predict residual stress which causes optical briefringence and mechanical warpage of silicone, finite element analysis was conducted for curing process during silicone molding. For analysis of curing process, a dynamic cure kinetics model was derived based on the differential scanning calorimetry(DSC) test and applied to the material properties for finite element analysis. Finite element simulation result showed that the slow cure reduced abrupt reaction heat and it was predicted decrease of the residual stress.