• Title/Summary/Keyword: encapsulment

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A numerical study on the residual stress in LED encapsulment silicone after curing and cooling (경화 및 냉각을 거친 LED 패키징 실리콘의 잔류응력에 대한 수치해석적 고찰)

  • Song, M.J.;Kim, K.H.;Kang, J.J.;Kim, H.K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.425-428
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    • 2009
  • Silicone is recently used for LED chip encapsulment due to its good thermal stability and optical transmittance. To mold a solid-state silicone encapsulment, curing by mixing at elevated temperatures followed by cooling is necessary. As the silicone molding process is involved in healing and subsequent cooling, the thermal residual stress, which causes mechanical warpage or optical birefringence in the final silicone encapsulment, may be induced if there are non-uniformities in cured silicone material properties or encapsulment shape design. The prediction of residual stress is necessary to design a high-quality silicone molding process. Therefore, in the present paper, a numerical parametric study was attempted to evaluate the heating and cooling effects on the thermal residual stress induced in the cured silicone.

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A numerical study on the residual stress in LED encapsulment silicone considering cure process (경화공정을 고려한 LED 패키징 실리콘의 잔류음력에 대한 수치해석적 고찰)

  • Song, M.J.;Kim, K.B.;Kang, J.J.;Kim, H.K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.323-327
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    • 2009
  • Silicone is recently used for LED chip encapsulment 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 both curing and cooling process during silicone molding. For analysis of curing process, a 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 curing as well as the cooling process should be designed carefully so as to reduce the residual stress although the cooling process plays the bigger role than curing process in determining the final residual stress state.

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A cure process modeling of LED encapsulant silicone (LED 패키징용 실리콘의 경화공정 모델링)

  • Song, Min-Jae;Kim, Heung-Kyu;Kang, Jeong Jin;Kim, won-Hee
    • Design & Manufacturing
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    • v.6 no.1
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    • pp.84-89
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    • 2012
  • Silicone is recently used for LED chip encapsulment 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 both curing and cooling process during silicone molding. For analysis of curing process, a 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 curing as well as the cooling process should be designed carefully so as to reduce the residual stress although the cooling process plays the bigger role than curing process in determining the final residual stress state. In addition, birefringence experiment was carried out in order to observe residual stress distribution. Experimental results showed that cooling-induced birefringence was larger than curing-induced birefringence.

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Finite Element Analysis of Residual Stress Evolution during Cure Process of Silicone Resin for High-power LED Encapsulant (고출력 LED 인캡슐런트용 실리콘 레진의 경화공정중 잔류응력 발달에 대한 유한요소해석)

  • Song, Min-Jae;Kim, Heung-Kyu;Kang, Jeong-Jin;Kim, Kwon-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.2
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    • pp.219-225
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    • 2011
  • Silicone resin is recently used as encapsulant for high-power LED module due to its excellent thermal and optical properties. In the present investigation, finite element analysis of cure process was attempted to examine residual stress evolution behavior during silicone resin cure process which is composed of chemical curing and post-cooling. To model chemical curing of silicone, a cure kinetics equation was evaluated based on the measurement by differential scanning calorimeter. The evolutions of elastic modulus and chemical shrinkage during cure process were assumed as a function of the degree of cure to examine their effect on residual stress evolution. Finite element predictions showed how residual stress in cured silicone resin can be affected by elastic modulus and chemical shrinkage behavior. Finite element analysis is supposed to be utilized to select appropriate silicone resin or to design optimum cure process which brings about a minimum residual stress in encapsulant silicone resin.