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© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Fraunhofer IZM Berlin
Entwicklungstrends im LED Packaging
Dr. Rafael Jordan
SIIT
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Agenda
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Optics
Cooling
Board
Phosphor
Submount
Underfill
Filling
Wire Bond
1st & 2nd Level
Interconnect
Chip
Power
LED Packaging Tasks
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
Agenda
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Development trends in assembly technology
Source: www.chipscalereview.com; “Waves of electronic packaging”; Amkor (new colors applied to graph, Fraunhofer IZM)
1980 1985 1990 1995 2000 2005 2010 2015 2020
0
10
20
30
40
50
60
70
80
90
100
Percent
Bare Die (COB)
Through Hole
(TO & DIP)
Surface Mount
(SO, PLCC, QFP, TAB)
Array
(Flip Chip, BGA,
CSP, Wafer CSP, PGA)
3D
(Stacked, MCM)
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Typical LED COB Modules
Source: www.chipscalereview.com; “Waves of electronic packaging”; Amkor (new colors applied to graph, Fraunhofer IZM)
lightinthebox.com
pollin.de
http://cloud6.lbox.me/images/v/201208/diy-20w-1600-1800lm-2800-3200k-warmweisses-licht-cob-led-strahler-mit-loch-30-34v_nufxyb1345794438856.jpg
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Challenges of COB applications compared to SMD
Selection of appropriate surface metallization and materials compatible with COB and SMT process steps
Selection of process sequence (COB prior SMT or vice versa)
Small pad geometries (die bond pad size 200 x 120 µm and smaller)
Handling of small dies (down to 200 x 200 µm²) on wafer tape
Availability of bare dies
Pad routing vs. pad size vs. minimum pitch
Surface cleanliness (avoid any possible contamination on surfaces, e.g. fingerprints, cleaning residues, outgassings, flux residues,oxides)
Surface topography (no scratches, no brush marks, low roughness Ra < 0.5 µm, no local defects on bonding pads)
Lifetime and reliability of silicone encapsulated wire bonds (interaction of loop strength, loop shape, thermal load, vibration load, material selection)
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
GaAs Flip-Chip
Reflector
active area
p-contact
p-GaAlAs
n-GaAlAs
n-contact
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Wireless GaN - Chips
wire
fo
r p
rod
uct co
mp
atibili
ty, b
ut n
ot e
sse
ntie
ll
Cree DA1000 OSRAM UX:3
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
Agenda
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Rth,int1
Rth,int2
Rth,TIM dA
RRbulk
theffth
10,,
2int,,1int,, thTIMththeffthRRRR
0 200 400 600 800 10000,0
0,5
1,0
1,5
2,0
2,5
Rth0
Rth
,eff [
K/W
]
BLT [µm]
TIM
~ 1/slop
Linear function
Q
TR
effth
,
Characterization of Thermal Interface Materials
~ 1-2 𝑾
𝒎∙𝑲
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Nanotechnologies to improve heat transfer
Multi modal
particles
Polymer fibres &
metallic alloy Surface micro-
structuring
Nano sponge
interfaces
Vertically aligned
CNT
Nano-scale optimization
Increase thermal
conductivity
Increase thermal
conductivity
Reduce BLT Reduce
interface resistance
Improve phonon transfer
Increase thermal
conductivity
TIM optimization Surface optimization Nano-scale optimization
Challenges for Glued Interfaces
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Cross Section LED on Leadframe Focus on Diebond
Failure Analyses Glued Die Bond
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Failure Analyses by Diode Characteristic
0,0 0,5 1,0 1,5 2,0
0
5
10
15
20
A11
F1
F3
F7
F8
F9
F16
I [m
A]
U [V]
F9
Cross Section LED on Leadframe U/I - Characteristics
pn-junction
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Agenda
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Supplier B 40 mil (LM) Supplier B 24 mil (LM)
Wetability of LED Dice
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Supplier A old design Supplier A new design
Wetability of LED Dice
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Supplier A new design Supplier A new design
Wetability of LED Dice
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
217°C
e1
278°C
e2
252°C
p: he+L1 L1+Aue
Au-rich Sn-rich
AuSn Phase Diagram
~ 60 𝑾
𝒎∙𝑲
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Copper Based LED on Silicon Substrate Reflow Soldering with AuSn no Activating Atmosphere x-ray
x-ray LED-Module 1 x-ray LED-Module 2
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Copper Based LED on Silicon Substrate Reflow Soldering with AuSn no Activating Atmosphere cross section
Cross Section Chip on Silicon
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
x-ray LED-Module 1 x-ray LED-Module 2
Copper Based LED on Silicon Substrate Thermode Soldering with AuSn no Activating Atmosphere x-ray
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Copper Based LED on Silicon Substrate Thermode Soldering with AuSn no Activating Atmosphere cross section
Cross Section Chip on Silicon
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Copper Based LED on Silicon Substrate Thermode Soldering with AuSn no Activating Atmosphere cross section close up look
Cross Section Chip on Silicon
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
~ 30 𝑾
𝒎∙𝑲
SnAgCu Phase Diagram
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Copper Based LED on Silicon Substrate Reflow Soldering with SnAg with Activating Atmosphere x-ray
x-ray LED-Module 1 x-ray LED-Module 2
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Copper Based LED on Silicon Substrate Reflow Soldering with SnAg with Activating Atmosphere cross section
Cross Section Chip on Silicon
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
• AlN/Si test board
for optical,
electrical, and
thermal LED
characterisation
Exsample (rigth):
• 8 SemiLeds LEDs
soldered on AlN
with AuSn
BMBF-Projekt
Nanolux - White
LEDs for General
Lighting
COB assembly LEDs on AlN
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
OSRAM LEDs on AlN Subassembly with wire bonds
Test Assembly with OSRAM LEDs
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
OSRAM LED Dice on metallized AlN Watercooler 600 W
http://www.excelitas.com/Index.aspx
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
OSRAM LED Dice on metallized AlN Watercooler, 600 W
http://www.excelitas.com/Index.aspx
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
OSRAM LED Dice on metallized AlN Watercooler x-ray
http://www.excelitas.com/Index.aspx
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Agenda
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Chip to Chip
Chip to copper
Assembly with Ag Sintering
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
SEM Pictures
Ag-Powder
after drying
Ag-Powder
heat without force
Ag-powder
heat and force
Ag Sintering
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Ag Sintered Interconnects comparing of two suppliers Cross Section with SEM
Cu
Ag Bond Ag Bond
Ag Plated Layer Ag Plated Layer
preparation effect AlN
supplier A supplier B
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Ag Sintered Interconnection, FIB Analys is
well defined
interface
Ag plated
Ag sintered
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Ag Sintered Interconnection, FIB Analys is
small pores almost
disoluted ~ 370 𝑾
𝒎∙𝑲
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
OSRAM LED Dice on metallized AlN Watercooler, 1200 W
pressure less sintering
http://www.excelitas.com/Index.aspx
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Shear Forces for Pressure Less S intered LEDs
Temperature Chip A on Ceramic
Chip B on Ceramic
Chip A on IMS
Chip B on IMS
225 °C (8,4 ± 2,1) N (8,8 ± 3,0) N (7,6 ± 3,1) N (7,5 ± 1,5) N
275 °C < 0,5 N (8,3 ± 1,9) N < 2,0 N (12,7 ± 2,9) N
http://www.excelitas.com/Index.aspx
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Pressure Less S intering pro/contra
Standard Equipment (Screen printer + P&P + Reflow)
No mechanical fixing of parts during sintering
No special atmosphere during sintering
Lower Shear forces than sintered/soldered dice
Metallization of die bond pad must be suitable
Smaller process windows (especially regarding drying)
http://www.excelitas.com/Index.aspx
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Agenda
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
soldering
annealing
Cu
Cu6Sn5
Cu3Sn
Si
Cu3Sn
TLPB us ing electroplated Cu/Sn
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
20 wt.-% Cu
40 wt.-% Cu
( Cu6Sn5)
Sn
Cu h Cu6Sn5
e Cu3Sn
40 wt.-% Cu (Cu6Sn5)
After soldering
Pore
40 wt.-% Cu
TLPS – SAC-paste plus Cu spheres
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Si-Chip
DAB
Proprietary Process and Paste
TLPS – SAC-paste plus 40 wt.-% Cu spheres
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Thermocompress ion Bonding with Stud Bumps
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Thermocompress ion Bonding with electroplated Bumps
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
densified
zone
bonding
zone
Flip Chip Sintering
80% pore
volume
13 nm pore size
Potential Application:
- low pressure, low temperature bonding (MEMS,
laser)
- compressible bonding (acommodate topography)
- containment for medical applications
- large surface area (sensors, catalytics)
- bio compatible (e.g. neuronal interface)
- optical devices (plasmonics, SERS)
H. Oppermann, M. Hutter, R. Jordan, et al. (Fraunhofer IZM)
Nano - Sponge
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Agenda
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Critical Value is the Junction Temperature
TJ?
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
The measurement current must be kept small, not to heat the die up, but out of the
horizontal area of the UI characteristic, as otherwise the recalculation of the
temperature will be imprecise. As Rp and Ri are different for every die, even within
one lot, each LED must be calibrated.
20 25 30 35 40 45 50 55 60 65 70 75 80 85
2,47
2,48
2,49
2,50
2,51
2,52
2,53
2,54
2,55
2,56
2,57
2,58
2,59
2,60
2,61
2,62
2,63
2,64
T = -t1 * ln (U/A1)
03B 2,637: T = -1152,913 ln(U/2,66220)
16B 2,620: T = -1398,438 ln(U/2,64008)
19B 2,640: T = -1220,828 ln(U/2,67310)
08B 2,642: T = -1179,331 ln(U/2,66607)
11B 2,634: T = -1423,025 ln(U/2,65662)
Sp
an
nu
ng
[V
]
Temperatur [°C]
2,4 2,6 2,8
0,000
0,001
0,002
0,003
0,004
0,005
Str
om
[A
]
Spannung [V]
testing range
Measuring Tj with the forward voltage, calibration
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Measurement Interpretation
Even within the realized switching time below 10 µs, a cooling of the LED is visible.
Therefore the record transient is fitted with a biexponential curve with offset. The first
half-value period is related to the thermal equilibration of the junction with the LED
die, the second for the equilibration of the die with the substrate. The offset is
simplified sum for the equilibration with the ambient and the final forward voltage at
ambient temperature.
0 1000
2,55
2,56
2,57
Sp
an
nu
ng
[V
]
Meßpunkt [Einheit]
0400mA = 2,58783 V = 25,1 °C
0 1000 2000
2,6
2,8
3,0
3,2
Sp
an
nu
ng
[V
]
T [µs]
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Example of a Flat Panel Light Source
0 200 400 600 800 1000 1200
2,505
2,510
2,515
2,520
2,525
2,530
2,535
LED@010mA at secundary current = 010mA = 2,535113 V = 24,16 °C
LED@050mA at secundary current = 050mA = 2,531410 V = 26,44 °C
LED@080mA at secundary current = 080mA = 2,528052 V = 28,51 °C
LED@120mA at secundary current = 120mA = 2,522847 V = 31,72 °C
LED@120mA at secundary current = 080mA = 2,525506 V = 30,08 °C
LED@150mA at secundary current = 150mA = 2,518709 V = 34,28 °C
LED@175mA at secundary current = 175mA = 2,515761 V = 36,11 °C
LED@200mA at secundary current = 200mA = 2,511649 V = 38,66 °C
LED@225mA at secundary current = 225mA = 2,508028 V = 40,91 °C
LED@250mA at secundary current = 250mA = 2,503836 V = 43,52 °C
Vo
lta
ge
[V
]
Time [µs]
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Test Szenario:
LED auf MC-PCB, MC-PCB auf Kühlkörper, T = 25,0°C
I1 = 100 mA, I2 = 350 mA, I3 = 700 mA
Thermal comparative study of 1 st Level Interconnect (gluing/soldering/s intering)
Water Cooler
Board
1st Level Interconnect
Chip 2nd Level Interconnect
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
0,000 0,002 0,0042,34
2,36
2,38
2,40
2,42
2,44
sample 1
sample 2
sample 3
U [V
]
t [s]
Thermal comparative study gluing/soldering/s intering e.g. blue LED glued
I1 = 100 mA
I2 = 350 mA
I3 = 700 mA
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
25,00
30,00
35,00
40,00
45,00
50,00
55,00
60,00
65,00
70,00
100,00 300,00 500,00 700,00 900,00 1100,00 1300,00 1500,00 1700,00 1900,00
T [
°C]
thermal load (optical emiss ion corrected) [mW]
'white' glued
'white' soldered
'white' sintered
Thermal comparative study: „white“ LED
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Agenda
• Chip on Board
• Gluing
• Soldering
• Sintering
• Transient Liquid Phase Bonding/Soldering
• Junction Temperature Measurements
• Silicon Interposer
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Variety of S ilicon Approaches
V1
V2
V3
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Thermomechanical Aspect of TSVs
Scallops
Pumping
Through Silicon Via (TSV)
TSV-Ø 6 µm
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Thermal Flow Simulation of TSVs
Johannes Jaeschke
silicon interposer with through silicon vias
Cu - via Si substrate
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Thermal S imulation of Vias
Silikon ausgeblendet Gesamtansicht
Unterseite LED
[°C]
Johannes Jaeschke
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
4,5
2 m
m
4,52 mm
0,1
0 m
m
0,16 mm
1,00 mm
Si-Board von 100 µm bis 200 µm variieren
0,5
0 m
m
3,5
2 m
m
4,5
2 m
m
Polymer oder Si-Rahmen hat eine Dicke von 300 µm
Approach for 8 Die Module
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Mechanical Analys is for Production
Modell 1 Modell 2
Johannes Jaeschke
Will the thin silicon bottom layer withstand the
quick pick & place process during assambly?
(force is only applied on the outside ring, no support in the center)
Parameter Variations:
thickness of bottom layer
technique of solder paste application
applied force
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Mechanical Modell (vertical deformation not to scale)
Si-tickness: 100 µm Si-thickness: 200 µm
(DPcurrent)
Si-thhickness: 100 µm diameter: 50 µm
Eq. stress
Total deformation
Eq. stress
Total deformation
(DP37)
Si-thickness: 100 µm diameter: 3000 µm
Johannes Jaeschke
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Adapted Design
TOP
1,00 mm
0,10 mm 0,20 mm0,10 mm
2,10 mm
3,50 mm
2,1
0 m
m
0,2
0 m
m
0,4
0 m
m
2,9
0 m
m
1,0
0 m
m
Bottom
0,2
0 m
m
0,4
0 m
m
0,1
0 m
m
2,5
0 m
m
2,9
0 m
m
0,40 mm
2,30 mm0,10 mm
3,50 mm
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
Air
Silicon-oil
Helium
Heat sink LED Bulb Simulation
© Fraunhofer IZM
Dr. Rafael Jordan, SIIT
Forschungsschwerpunkt Technologien der Mikroperipherik
LED Bulb Simulation