Solid State Lighting Technology and Applications (PH230)

Synopsis

What You Will Learn

• Compound semiconductors and light emitting devices
• LED device electrical-thermal-optical characteristics
• Light extraction techniques in LED chip
• Generation of white light
• Characterization and testing of white light
• Various white LED package designs
• Package design considerations for white LEDs
• Solid state lighting market and applications
• LED lighting module and driver system
• Regulatory requirements and incentive schemes

Who Should Attend 

PrerequisiteInterest in the science of LED and LED systems in lighting and desire to acquire better understanding in this area in terms of theory and applications. Technical background in electrical/electronic/mechanical engineering or physics degree would be desirable.

Course MethodologyIn this course the audience is first introduced the basics of LED technology, tracing the beginnings of the LED technology to the compound semiconductor industry. A recent solid state technology, i.e. OLED, will also be examined briefly and compared and contrasted to the LED technology. The basic electrical, optical, and thermo-mechanical properties of LEDs is surveyed, and its implication on the application is discussed.

In the next section, a discussion on the evolution of the LED chip design improvement is traced, examining the improvement in light extraction techniques as an example. White light LED technology is then introduced and the RGB vs phosphor LED approaches are examined and compared. In providing the understanding of white LED, the nature of white light and its measurements and characterization is also outlined, including a discussion on the color rendering index, the correlated color temperature, and other color science terminologies.

Also described is the phosphor technology and the process of deposition or coating, and its effect on the efficiency of the device. The optical characteristics of phosphor is also studied and related to its performance in the LED package.

This course also includes an outline of the LED packaqe design and thermal considerations in relation to high power LEDs used in lighting applications. The thermal resistance property of the LED package and its implication to operating current and ambient temperature will be discussed and illustrated with examples.

Lastly, the course ends with a survey of the market applications and an examination of the latest regulation requirements and incentive schemes offered by regional markets such as in the North America and Europe.

Course Duration2 days, 9am - 5pm

Course Structure

Compound semiconductors and light emitting devices
Visible LEDs
UV
IR
Laser Diodes
Others - OLED

LED device electrical-thermal-optical characteristics
Forward and reverse voltage characteristics
Maximum junction temperature rating
Maximum current and power ratings
Thermal resistance of LED
Deriving and interpreting the derating curve
Viewing angle and radiation pattern

Light extraction techniques in LED chip
Chip shaping
Current spreading
Metal bonding
DBR
Surface morphology
Evolutionary progress of LED efficiency

Generating white light
RGB vs phosphor white - advantages and disadvantages
Phosphor technology

• Phosphor types
• Excitation wavelength - From UV to blue LEDs
• Factors affecting phosphor efficiency
• Absorption spectra
• Emission spectra
• Mean particle size
• Mean path length
• Phosphor deposition techniques

RGB technology

• LED spectra
• Comparative LED efficiencies
• Color mixing theory
• RGB ratio of white light using LEDs
• NTSC color space vs LED color space

Characterization and testing of white Light
Color coordinates and white LED binning structures
Correlated Color Temperature (CCT)
Color Rendering Index (CRI)
Interpreting LED-phosphor emission spectrum
Radiation pattern characteristics and impact on applications
Iv degradation over time
Color degradation/shift over time
Iv and color shift vs operating temperature
Lifetime definition of CFL/Fluorescent vs LED lamps

Various white LED package designs
Bicolor LEDs
Tricolor LEDs
Phosphor-coating on LED chip
Phosphor deposition on LED chip
Phosphor-film/plate over LED chip
Phosphor-in-elastomeric cap over LED package
UV LEDs
Dual phosphor LEDs
Tri-phosphor LEDs

Package design considerations for white LEDs
Thermal management
Modes of heat transfer - conduction, convection and radiation effects
Substrate material characteristics and selection guide
Thermal modeling for conduction, convection and radiation
Heat sink designs and materials
Thermal stress generation and avoidance
Thermal heat path optimization
Thermal analysis software

Solid state lighting market and applications
LCD TV, PC, laptop backlighting
Mobile appliances backlighting
Camera flash LEDs
Automotive lighting
Street lighting
Cold storage lighting
Industrial/warehouse lighting
General commercial lighting
Domestic lighting

LED lighting module and driver system
DC power supplies

• AC-DC conversion technologies - SMPS
• Buck-boost converter
• Fly-back converter
• Power factor correction requirements
• Conversion efficiency

Constant current drive vs constant voltage drive
PWM drive
EMI requirements
Ingress Protection (IP) ratings
Regulatory efficiency requirements
Optical components

• Reflectors
• Light pipes
• Diffusers
• Prism plate
• Material properties and selection: Refractive index, transmissivity, density, processability

Regulatory requirements and incentive schemes
US/Canada - Energy Star requirements
UK - Enhanced Capital Allowance (ECA) Scheme