CFD Analysis Process of LED Packaging ATES
Agenda ATES 소개 ATES 연혁 지원시스템 Icepak 소개 모델링방법 재질및경계조건의설정 격자생성및 Solving Parametric Analysis & Optimization 비등방성열전도율 Icepak을이용한 LED 해석사례 (1) 한국광기술원, 메디아나전자 Icepak을이용한 LED 해석사례 (2) 한국광기술원
ATES 연혁 1990 년 CIES 설립 1991년 IBM SR 지정, 각종 SW 독점공급계약체결 Fluent(`91) CATIA DASP(`93) MAGMA(`93) ADINA(`94) SFTC(`95) 1995년 ATES 설립각종 SW 독점공급계약체결 POLYFLOW, MIXIM, FIDAP(`96) ICEPAK, ACERC(`96) FIELDVIEW(`97) PAM/STAMP, CRASH, SERIES(`97) MSC/PATRAN, MSC/NASTRAN(`98)
기술지원 On-site support Engineering consulting Homepage BBS Technical Note E-newsletter Customer Application Seminar Production Seminar User Group Meeting Training 기본교육 응용교육 고급교육 교육센터운영
Modeling Icon을이용 Macro Key Cad data의 Import E-Cad : IDF M-Cad : IGES, Step, Tetin Data : CSV, Excel IcePro의이용 3D 3D Cad Cad data data Icepak Icepak Model Model 계산결과계산결과확인확인
재질및경계조건의설정 고체, 액체및기체의풍부한재질 Library 구축 Package, Fan, Filter 및 Thermal interface 관련 Library 구축 Wizard 형식의설정방법 경계조건의경계조건의Wizard type type 설정설정 Icepak Icepak Libraries Libraries
격자생성및 Solving ICEM CFD Engineering 社의 Hexa, Tetra Mesh를이용하여단시간내에 Mesh를자동생성함. Solver는별도의설정없이 Wizard 창에서클릭한번으로구동됨. 격자격자Wizard 및격자의모습및격자의모습 Solver Solver Wizard Wizard 모습모습
Parametric Analysis & Optimization Geometry, Velocity, Heat Dissipation 등의변수화로 Optimizing Analysis 수행 변수지정 Best Case
비등방성열전도율 PCB, IC Package 등의일반적 Material 의경우비등방성열전도율을갖게됨. 수지계열 ( 작은열전도율 ) 동계열 ( 큰열전도율 ) 수직방향 ( 작은열전도율 ) 수평방향 ( 큰열전도율 ) Icepak 은열전도율을 4 가지 Mode 로표현가능함. Isotropic ( 등방성 ) Orthotropic ( 직교비등방성 ) Anisotropic ( 완전비등방성 ) Biaxial (2축비등방성 )
Icepak 을이용한 LED 해석사례 (1)
SMD Type LED 의각요소의 Geometry 의변화에따른최고온도의변화예측 한국광기술원, 메디아나전자 ATES
AGENDA 1. Geometry & Conductivities 2. CASE 1 : Sapphire 두께변화에따른최고온도의변화 3. CASE 2 : Lead의형상및면적변화에따른최고온도의변화 4. CASE 3 : Thermal Paste의도막두께의변화에따른최고온도의변화 5. 결과및고찰 6. CASE 4 : Heat Sink 최적화 7. Heat sink 최적화에따른결론
Geometry SI Sub-mount Sapphire Heat Slug Lead Thermal paste Body Cathod Solders Anod Sub
Conductivities 실질적으로실질적으로LED LED가원활한원활한동작을동작을하는 Cooling Cooling 조건을조건을만들어주기만들어주기위하여위하여임의의 Heatsink Heatsink를장착한장착한모습 Heatsink Heatsink제원제원알리미늄알리미늄사출사출,, 30X10X30mm,8fin(1.4t) 각부요소의명칭 Sapphire SI subment Lead P-Solder Thermal Paste Body Sub material Cathod/Anod 열전도도 50 W/m-K 180 W/m-K 387.6 W/m-K 50 W/m-K 50.2 W/m-K 0.08 W/m-K 0.08 W/m-K 313.0 W/m-K
CASE 1 (N-GaN 두께변화에따른최고온도의변화 )
Boundary Condition 주변공기온도 : 20 Steady state Analysis : 완전열평형상태 Laminar Scheme 사용 Buoyancy force 적용 Radiation effect 적용 (Stefan Boltzmann s eq. 사용 ) 발열량 : 1 Watt N-GaN 의두께변화 : 0.015, 0.020, 0.025 mm
Model and Mesh Mesh type :Hexa-unstructured mesh Non-Conformal Mesh 사용 Number of Mesh : 약 21 만 5 천여개 Plane Plane Cut Cut Emitter Emitter & Lead Lead 部
Temperature Contour Sapphire Sapphire 두께두께 :: 0.015mm 0.015mm Sapphire Sapphire 두께두께 :: 0.020mm 0.020mm N-GaN 두께 0.015 mm 0.020 mm 0.025 mm 최고온도 ( ) 86.00 84.65 83.89 Sapphire Sapphire 두께두께 : : 0.025mm 0.025mm
CASE 2 (Lead 의형상및면적변화에따른최고온도의변화 )
Boundary Condition 주변공기온도 : 20 Steady state Analysis : 완전열평형상태 Laminar Scheme 사용 Buoyancy force 적용 Radiation effect 적용 (Stefan Boltzmann s eq. 사용 ) 발열량 : 1 Watt N-GaN의두께 : 0.015 mm Heat sink와접하는 Lead의크기 : 1.9X2(3.8), 2.5X2(5.0), 3X2(6.0)
Temperature Contour Lead Lead :: 1.9X2(3.8mm 1.9X2(3.8mm 2 2 )) Lead Lead :: 2.5X2(3.8mm 2.5X2(3.8mm 2 2 )) Lead 면적최고온도 ( ) 2.5 mm 2 3.8 mm 2 86.0 86.08 6 mm 2 86.21 Lead Lead :: 3.0X2(6mm 3.0X2(6mm 2 2 ))
CASE 3 (Thermal Paste 의도막두께의변화에따른최고온도의변화 )
Boundary Condition 주변공기온도 : 20 Steady state Analysis : 완전열평형상태 Laminar Scheme 사용 Buoyancy force 적용 Radiation effect 적용 (Stefan Boltzmann s eq. 사용 ) 발열량 : 1 Watt N-GaN의두께 : 0.015 mm Heat sink와접하는 Lead의크기 : 1.9X2(3.8) Thermal Paste 도막의두께 : 0.05, 0.07, 0.09mm
Temperature Contour Thermal Thermal Paste Paste :: t=0.05mm t=0.05mm Thermal Thermal Paste Paste :: t=0.07mm t=0.07mm 도막두께 0.05mm 0.07mm 0.09mm 최고온도 ( ) 86.00 86.19 86.34 Thermal Thermal Paste Paste :: t=0.09mm t=0.09mm
결과및고찰 N-GaN 의두께가 Emitter 의최고온도에미치는영향은 0.015mm 에서 0.025mm 으로 0.01mm 변화에대하여 2.61 의온도편차를보였다. 다시말하면이는 0.26 /micron 이라는막대한영향을미친것이다. 이것은 N-GaN 이 130W/m-K 의비교적높은열전도도를갖고있으면서 Sapphire 및 Sapphire 를 Body 와연결하는 solder ball 와직접연결되어있는부분이므로효과가큰것으로사료된다. Board 에직접닿는 Lead 의면적을 2.5mm 2 에서 6.0mm 2 으로변경시키면서결과를살펴보았으나발열부의온도에미치는영향이미미하여고려의가치가낮은것으로판단된다. 이것은발열부의열이 lead 보다 heat slug 를통하여열전달되는양이많기때문이다. SI-Sub mount 와 LED 의 Heat slug 부분을연결하는 Thermal paste 의두께의영향에대하여알아보기위하여도막두께를 0.05mm, 0.07mm, 0.09mm 로변화시키면서발열체의최고온도를분석했다. 도막의두께가 0.05mm 에서 0.09mm 로 0.04mm 두꺼워짐에의하여온도는 0.34 상승했다. 이는 0.0085 /micron 으로서비교적큰영향을미치는인자로생각할수있다. 이외에도많은인자들이어느정도의영향을미칠것인가를찾아낸다면실질적으로 LED Packaging 분야는물론냉각시스템의전반적인열및유동적특성을고려한설계가이루어질수있을것으로판단된다.
CASE 4 (Heat Sink 최적화 )
Boundary Condition 주변공기온도 : 20 Steady state Analysis : 완전열평형상태 Laminar Scheme 사용 Buoyancy force 적용 Radiation effect 적용 (Stefan Boltzmann s eq. 사용 ) 발열량 : 1 Watt N-GaN의두께 : 0.015 mm Heat sink와접하는 Lead의크기 : 1.9X2(3.8) Thermal Paste 도막의두께 : 0.05mm Heat sink의 Fin의수량및두께에따른일련의해석 => Parametric 기능이용 Heat sink 제원 : 알리미늄사출 최외곽크기 Fin 두께 Fin 갯수 30X10X30mm 1.0, 1.2, 1.4 6, 8, 10, 12
해석에사용된 Heat sink 의제원
Heat sink 의사양에따른온도결과 Maxmum Temp. at Emitter 86.5 86.0 85.5 85.0 84.5 84.0 83.5 83.0 82.5 Fin 개수 : 6 Fin 개수 : 8 Fin 개수 : 10 Fin 개수 : 12 최저온도 t=1.0 t=1.2 t=1.4 t=1.0 t=1.2 t=1.4 t=1.0 t=1.2 t=1.4 t=1.0 t=1.2 t=1.4 Fin Fin의두께두께 (mm) (mm)
최적화된 Heat sink 의온도및속도장
Heat sink 최적화에따른결론 Heat sink의정해진외곽사이즈에서 Fin의개수및두께를변화시켜가면서최적의사양을유추한다. 최저온도는 heat sink의 fin의두께가 1.0mm이고 fin의개수가 8개일때및 fin의두께가 1.0, 1.2mm이고개수가 10개일때나타났다. Fin의개수가 12개일때에는 fin의두께가두꺼워질수록효과가오히려더욱악화되는경향이나타났는데, 이는 fin과 fin 사이의유동의속도가오히려느려졌기때문이다. 그렇지만정해진 heat sink의외곽크기의한계내에서는 LED의관리온도기준인 80 를맞추지못하므로 heat sink의크기를좀더크게해야할필요성이요구된다. 또한 heat sink의온도분포를보면 LED의 heat slug에의한열의방열이매우우수함을볼수있다. 이는또한 Lead의면적이큰영향을주지못하는이유이기도하다.
Icepak 을이용한 LED 해석사례 (2) ( 한국광기술원반도체공학회발표자료 )
Full Scheme 3D View of Design & Proto-Type Sample HP(High Power) Chip, Ceramic Package,PCB Ceramic Package HP Chip SMD Solder PCB
Specification of Wire Bonding Chip Specification Feature Growth Technique MOCVD Substrate Sapphire (0001) Structure InGaN MQW Chip size 1000±30μm 1000 ±30μm Wafer thickness 100± 5 μm Testing & sorting 100 % Packaging 20cm±5mm 20 cm±5mm (blue tape medium tack) Backside reflector Al metal Non Bin Number Blue Brightness(-X mw) 3 Dominant Wavelength(nm) V f (V) -1-2 -3-4 -5-6 Min Max Typ Max ELO-BCRE455-X 60~80 80~100 100-120 120-140 140~ 455 460 3.8 4.5 ELO-BCRE460-X 60~80 80~100 100-120 120-140 140~ 460 465 3.8 4.5 ELO-BCRE465-X 60~80 80~100 100-120 120-140 140~ 465 470 3.8 4.5 ELO-BCRE470-X 60~80 80~100 100-120 120-140 140~ 470 475 3.8 4.5
Union of each part P-GaN & Electrode Chip Modeling N-GaN Buffer Layer Dimension Size 1 mm 1 mm Sapphire & Paste Thickness P-GaN N-GaN Buffer 2.12 mm 4 um 0.5 um Sapphire &Paste 80 + 25 um
Spec. of each part Package & PCB Modeling LED Chip Reflector Body Package Sub. PCB Solder Paste Material GaN /Sapphire Ceramic Ceramic FR-4 (Compact Via) Pb 39.2 Sn 60.8 Epoxy Thermal Conductivity(W/m-K) 130 15 15 X,Z : 2.3 Y : 2.9 50 0.3 Dimension(mm 2 ) 1 1 50 50 50 50 300 300 50 10 1.1 1.1 Thickness 80 um 500 um 400 um 350 um 10 mm 25 um
Pre-simulation Results (Unit : W) Input Power Vs. Junction Temperature 1 2 3 4 Input Power 0.2 0.4 0.6 0.8 Junction Temperature 61.20 94.73 128.27 161.80 Max. Junction Temperature 180 160 140 120 100 80 60 Regression Formula - Max. Junction Temperature = 167.78*Input Power + 27.66 40 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Input Power(W)
Electrical PWR : 0.372 W Evaluation Results Label Value Li1: Max 65.4 C Li1: Min 33.6 C Li2: Max 58.5 C Li2: Min 36.6 C Li3: Max 54.8 C Li3: Min 37.7 C Li4: Max 54.1 C Li4: Min 37.6 C Li5: Max 58.5 C Li5: Min 38.4 C Ar1: Max 65.8 C Ar1: Min 39.7 C
Evaluation Results Electrical PWR : 0.752 W Label Value Li1: Max 118.0 C Li1: Min 41.0 C Li2: Max 101.2 C Li2: Min 51.8 C Li3: Max 104.7 C Li3: Min 49.6 C Li4: Max 91.2 C Li4: Min 52.5 C Li5: Max 92.8 C Li5: Min 56.5 C Ar1: Max 118.0 C Ar1: Min 99.3 C
Relative Heat Transfer rate Loss of Current Spreading Eval_Temp. Eval_PWR Regre_PWR Optical PWR Changed Heat(%) Current Spreading Loss(%) 65.980 0.372 0.229 0.16 61.43 22.57 119.620 0.728 0.548 0.16 75.33 8.67 Percentage of Loss(%) 24 22 20 18 16 14 12 10 Heat Transfer Rate = Electrical Input Power [100 - (Percent of Optical Power + Current Spreading Loss)] 8 6 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 Electrical PWR(W)
PWR : 0.229 W Re-Simulation Results N-GaN P-GaN Sapphire Paste Package_Sub Package_Ele Reflector Solder PCB Thermal Resistance Min 65.79 65.91 64.22 55.96 50.27 50.27 50.47 48.46 29.83 Max 66.12 66.09 65.98 65.33 61.24 51.73 52.98 50.94 50.32 38.690 Mean 66.00 66.00 65.64 62.03 52.56 50.78 51.68 50.13 33.48
Re-Simulation Results PWR : 0.229 W < P-GaNP > < Sapphire > < PCB > < LTCC_Sub > N-GaN P-GaN Sapphire Paste Package_Sub Package_Ele Reflector Solder PCB Thermal Resistance Min 65.79 65.91 64.22 55.96 50.27 50.27 50.47 48.46 29.83 Max 66.12 66.09 65.98 65.33 61.24 51.73 52.98 50.94 50.32 38.690 Mean 66.00 66.00 65.64 62.03 52.56 50.78 51.68 50.13 33.48
Evaluation Results T3Ster 36.01K/W
PWR : 0.548 W Re-Simulation Results N-GaN P-GaN Sapphire Paste Package_Sub Package_Ele Reflector Solder PCB Thermal Resistance Min 118.76 119.03 115.07 95.57 82.17 82.18 82.56 77.98 34.83 Max 119.48 119.42 119.18 117.69 108.05 85.64 88.54 83.82 82.19 46.056 Mean 119.28 119.27 118.42 109.91 87.56 83.44 85.48 81.91 43.15
Re-Simulation Results PWR : 0.548 W < P-GaNP > < Sapphire > < PCB > < LTCC_Sub > N-GaN P-GaN Sapphire Paste Package_Sub Package_Ele Reflector Solder PCB Thermal Resistance Min 118.76 119.03 115.07 95.57 82.17 82.18 82.56 77.98 34.83 Max 119.48 119.42 119.18 117.69 108.05 85.64 88.54 83.82 82.19 46.056 Mean 119.28 119.27 118.42 109.91 87.56 83.44 85.48 81.91 43.15
T3Ster Evaluation Results 42.79 K/W
Simulation Results of Multi-Chip Package
Full Scheme 3D View of Design & Proto-Type Sample Reflector,LTCC &Metal Substrate on Large Finned Heat Sink Reflector LTCC Metal Substrate Finned Heat Sink
Wire Bonding Chip Structure Merge Heat Source Sapphire : Al 2 O 3 Name Material Height Name Material Height Sapphire Al 2 O 3 90 100 um P-Metal Ni / Au 0.3 um Protection SiO 2 - P-Electrode Ni / Au 2 um N-GaN GaN 4 um N-Metal Ni / Au 0.5 um MQW InGaN/GaN - N-Electrode Ti/Al/Pt/Au 2 um P-GaN GaN 0.12 um Reflector Ag 0.5 um
LTCC Design Drawing 3-D D View Top/Side View Material Dimension Layer No. Thickness Bonding Pad Soldering Pad Ceramic 48 45 mm 2 1mm 0.5 2 mm 5 5 mm
Reflector Design Drawing 3-D D View Top/Side View Material Dimension Angle Thickness Plating Copper 7 7 mm 100.5 3.4 mm Silver
One of multi-arrayed structure Modeling Reflector LTCC Encapsulant Material Property LED Chip Ag Epoxy Beacon Heat Sink Modify Heat Source Sapphire : Al 2 O 3 Reflector LTCC Encapsulant LED Chip Paste Beacon Heat Sink Material Copper Ceramic Silicon Sapphire Ag Epoxy Aluminum Aluminum Thermal Conductivity 387.6 26 0.23 50 3 240 240
Modeling Heat Sink 3-D D View Top/Side View Index Value Index Value Type Extruded Thickness 1.8 mm Material Aluminum Space 2.34 mm Height Base Over 5mm 30mm Dimension Pin Count 60 68 mm 17
Modeling Reflector Union of each part LTCC Dimension Size 49 mm 49 mm Metal Plate Reflector 3.4 mm Thickness LTCC Metal Plate 1 mm 3 mm Total 4 mm
Modeling Modeling of junction section between units Union Section Reflector & Heat Sink Sapphire & Beacon LTCC & Heat Sink Reflector & LTCC Material Ag Epoxy Ag Epoxy Ag Epoxy Ceramic Object Thin Plate Thin Plate Thick Plate Thin Plate
Contour Plot Temperature Distribution Electrical Power : 0.15W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 0.080 41.40 40.40 41.40 41.02 39.35 40.67 39.52 1.06 0.73 1.50 2.05
Temperature Distribution Contour Plot Electrical Power : 0.471W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 0.31 81.79 79.55 81.79 80.93 77.17 80.14 77.56 2.38 1.65 3.37 4.61
Temperature Distribution Contour Plot Electrical Power : 0.56W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 0.39 106.08 102.60 106.08 104.74 98.90 103.52 99.50 3.70 2.56 5.25 7.18
Temperature Distribution Contour Plot Electrical Power : 0.732W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 0.55 128.81 124.10 128.82 127.00 119.08 125.35 119.88 5.02 3.47 7.12 9.74
Temperature Distribution Contour Plot Electrical Power : 0.898W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 0.74 150.39 144.42 150.39 148.09 138.08 146.00 139.10 6.34 4.39 9.00 12.31
Temperature Distribution Contour Plot Electrical Power : 1.061W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 0.89 171.16 163.94 171.15 168.38 156.28 165.85 157.51 7.66 5.30 10.87 14.87
Temperature Distribution Contour Plot Electrical Power : 1.221W Three Dimensional View Cross-Sectional View SRC PWR Source Sapphire Beacon Deviation Max Min Max Mean Min Max Mean Min Max Mean Effective Dev. 1.03 191.73 183.29 191.74 188.49 174.30 185.52 175.74 8.98 6.22 12.74 17.43
Re-Simulation of Non Finned Heat Sink Type Simulation Result Deviation between parts Actual Total PWR Mean Dev. Eff. Dev Rth_Mean Rth_Eff 2.40 1.50 2.05 0.62 0.85 6.11 3.38 4.62 0.55 0.76 8.96 5.25 7.18 0.59 0.80 11.71 6.66 9.75 0.57 0.83 14.37 9.01 12.31 0.63 0.86 16.98 10.88 14.88 0.64 0.88 19.54 12.75 17.45 0.65 0.89 R th_eff Sapphire Beacon R th_mean R th_mean : (Mean. Temp. of Sapphire - Mean. Temp. of Beacon) / PWR R th_eff : (Max. Temp. of Sapphire - Min. Temp. of Beacon) / PWR Temperature of others Actual Total PWR Heat_Spreader LTCC Encapsulant Reflector 2.40 39.40 39.45 41.40 39.36 6.11 50.68 50.79 55.19 50.60 8.96 59.95 60.12 66.96 59.83 11.71 61.00 61.22 70.44 60.84 14.37 76.37 76.65 88.39 76.15 16.98 83.53 83.87 98.05 83.27 19.54 90.41 90.81 107.44 90.10
Conclusion
Chip / Package Level Effect of Current Spreading Conclusion Heat transfer rate obtained from the experiment results q = Power Electrical Thermal Resistance of Package Level Deviation Ratio [ 100 ( R + R )] Optical _ Power Loss _ Current _ Spreading Electrical PWR Simulation(K/W) Evaluation(K/W) Ratio(%) 0.365 38.69 36.01 6.93 Error 0.734 : within 10 % 46.056 42.79 7.09 Multi_Chip Package Thermal Resistance Deviation between simulation results and evaluation results 0.235 K/W(21%)
Conclusion Thermal paste thickness and property between Heat sink and Heat Spreader Need correlation and compensation Development Results Heat emission with only heat sink Determination of distance between HP LEDs Can be applied to lighting products