China SSL 2012

Designing and Delivering Quality in SSL

mark_mcclear@cree.com

November 5, 2012

SSL Quality Begins with the LED Lamp

• LED lamp types, construction
• Sources of light degradation
• Applications impact
• Right LED lamp for the application

Copyright © 2012 Cree, Inc. pg. 3

An LED Lamp is a Complex System

LED Chip:
– Determines raw
brightness and efficacy
Phosphor system:
– Determines color point,
color quality and color
point stability
Package:
– Protects the chip and
phosphor
– Helps with light and heat
extraction
– Primary in determining LED
lifetime


Different LED Lamp Architectures

Ceramic Substrate,
Silicone Dome

Large COB array,
Al, Ag Substrate

Molded Plastic Package,
Silver Lead Frame

“High Bright” LEDs designed
for consumer applications


Different Sources of Light Degradation
2. Phosphor Degradation 3. Silicone Encapsulant
Degradation

1. Chip Degradation
3 Sources

4. Al, Ag Substrate Degradation 3. Silicone Encapsulant
Degradation
2. Phosphor Degradation

1. Chip Degradation 5 Sources
5. Plastic Degradation

2. Phosphor 3. Silicone Encapsulant
Degradation Degradation

4 Sources
1. Chip Degradation 4. Plastic Degradation

LED Chip Degradation (Generic, all types)

100%

90%
% LF

80%

70%

Time (hours) 50,000

• LED chips actually get brighter over the first 10-
20k hours of operation
• Real LED chip degradation is very, very slow…

Phosphor Degradation (Generic, all types)
100%

90%
% LF

80%

70%

Time (hours) 50,000

• Phosphors are chemically very stable over time
also

Possible Sources of Phosphor Degradation
Illuminated
Object

Phosphor
LED Chip
Phosphor coating is put on chip, generally does not degrade

Phosphor can peel at the edges, let less blue light through to
be converted – color shift, loss of light

Micro-delaminations can occur over time, thermal stress –
further loss of light, potential for color shift

Encapsulant Degradation (Generic, all types)

100%

90%
% LF

80%

70%

Time (hours) 50,000

• Rapid initial degradation (first 5k hrs), stable
long term

Encapsulant Degradation Source

• Silicone encapsulants theoretically cross-link like
this:
R R R R

Siloxane Si O Si O Si O Si O
(R2SiO)n
R R R R

• Silicone encapsulants actually cross-link like this:
R O
R R R R O R
R O Si O
CO Si O Si O Si O
Si O
Si Si
O O CH3 O
Si Si O
Si Si
O SiO O
CH3
Si O Si O Si O Si O
R CH3 Si R R
R CO2 R R CO
R CO2 Si R R R
R Si R R

• …and a lot of *stuff* comes off them…
• Weight loss can slightly reduce RI, long stranded
polymer chains can turn brown/absorb light…

Plastic & Metal Substrate Degradation

100%

90%
% LF

80%

70% Metal (Al, Ag)
Plastic

Time (hours) 50,000

• Similar degradation profiles, plastic
degradation is typically a bit more pronounced

Plastic & Metal Degradation Mechanism

• This LED lamp architecture depends on metal
substrate and plastic sidewall reflectivity
• Plastic can degrade under photon bombardment
and thermal stress
• Metal can tarnish due to application
environmental conditions (moisture, sulfur, etc.)
• Both can reduce LED lamp light output…

Plastic Degradation in Low Cost Packaging

100%

90%
% LF

80%

70%

Plastic

Time (hours) 50,000

• Plastic degrades quickly and blocks light in this
package architecture
• No metal to reflect the light

Combined: Ceramic/Silicone Dome

100%

90%
% LF

80%

LED Chip
Phosphor
70% Encapsulant
Combined
3 Sources

Time (hours) 50,000

• Typical LM-80 performance at 85°C, med-high
current density (chip size dependent)

Combined: Plastic/Metal LF, Substrate

100%

90%
% LF

80%

LED Chip
Phosphor
70% Encapsulant
Metal (Al, Ag)
Plastic
Combined
5 Sources

Time (hours) 50,000


Combined: “High Bright” LEDs

100%

90%

LED Chip
Phosphor
% LF

80% Encapsulant
Plastic
Combined
70%

4 Sources

Time (hours) 50,000


Typical LM-80 Performance by Lamp Type
100%

Ceramic/Silicone Dome
90%
% LF

80%
Plastic, Leadframe / COB

70%

“High Brightness” LEDs
5mm LEDs

Time (hours) 50,000
• Ceramic/Si Dome LED lamp architecture generally have superior
Lumen Maintenance vs. Plastic/Metal architectures
• Both can be Lighting-class, always demand the LM-80 report
• HB LED Lamps – demand the LM-80 report
• 5mm lamps – LM-80 is NOT defined

Light Degradation at the Application Level
Time zero 1000 hours

Brightness

Color


This may be OK for
some consumer
applications

☼ Brightness


☼ Brightness


We don’t typically
have this kind of
control on our lights…

☼ Brightness


☼ Hue


No remote control
for this either…

☼ Hue


Is it OK for this Application??

Probably for
some markets,
probably NOT
for others


Very Application Dependent

As Installed

3 Months Later

You don’t want to
be that guy…


Select the Right LED For Right SSL Application

• LED lamps are
complex systems
with different parts XLamp
XP-G2
XLamp
XP-G
XLamp
XP-E
XLamp
XP-C
that degrade at
different rates XLamp XLamp XLamp XLamp XLamp XLamp
XB-D XPE-HEW XT-E XTE-HV XM-L XML-HV
• Quality and reliability
in SSL applications
can be very
dependent on the XLamp MP-L XLamp MT-G2 XLamp MT-G XLamp MC-E
LED lamp
architecture
• High Bright and 5mm XLamp MX-6

LEDs should not be
XLamp ML-E/C/B XLamp CXA2011 XLamp XLamp
used for most CXA1507/12 CXA2520/30
Lighting Applications

China SSL 2012

Recommended

Recommended

More Related Content

Similar to China SSL 2012

Similar to China SSL 2012 (6)

More from Mark McClear

More from Mark McClear (6)

China SSL 2012