LED Packaging 2011 T
A comprehensive survey of the main LED packaging technologies and market metrics.
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45 rue Sainte Genevive, F-69006 Lyon, France Tel: +33 472 83 01 80 - Fax: +33 472 83 01 83 Web: http://www.yole.fr
2011
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Scope of the Report (2): Process Steps
This report covers the Back-en level 0 and level 1 of the High Brightness LED manufacturing process
Front end Level 0: Epitaxy
Nucleation layer n type layer Active layers (MQW) p-type layer
Substrate
SiC Sapphire Silicon Bulk GaN Composite substrates
Back-End (Packaging) level 0:
Laser Lift-Off (LLO) Substrate separation - Bonding Die singulation Testing and Binning.
LED dies
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LED epi-wafer
Front-End Level 1: Device Making
Inspection Masking / Lithography Etching Metallization/contacts/mirrors
LED dies-on-wafer
Mesa LED structure Flip Chip LED structure Vertical LED structure
Back-End (Packaging) level 1:
Die Attach and interconnect Phosphor Encapsulation and optics Testing and binning
Packaged LED
Sources: Yole Dveloppement
2011
Copyrights Yole Dveloppement SA. All rights reserved.
LED Packaging 2011
GaN Capacity vs. Demand:
MOCVD reactors shipment volume is a good metric to gage the overall equipment market. After the tight supply situation experienced in early 2010 for packaged LEDs, the current equipment investment cycle driven by massive investments in China will lead to an overcapacity buildup that could take 12-24 months to absorb. However, our accelerated scenario calls for a minimum 5.4 million of Two Inch Equivalent (TIE) per month reactor additional capacity necessary for the 2012-2015 period. Considering a typical average industry utilization rate of 85%, this number could realistically be up to 7.2m TIE.
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Capacity increase needed: 5.4m TIE/month
Yole Dveloppement - Updated May 2011
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Project Sapphire
Typical Process Flow:
Carrier wafer Carrier wafer Epitaxial substrate Epiwafer
Die
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Lens
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Osram Oslon
Exact process is product dependant and varies from one manufacturer to another. For example substrate removal and wafer bonding are only used for the manufacturing of vertical LED structures, But some manufacturers of vertical LEDs use technologies that dont require wafer bonding. Numbers and positions of testing and inspection steps can also vary.
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Packaging Overview
GaN LED Chip Design Overview: Trends:
Structure Trends Comment
- Standard mesa structures remain the most cost effective solution for applications and design requiring low current densities ( low heat generation)
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- Flip chip designs have been widely adopted by Philips Lumileds for all their GaN high power packages that are being increasingly used for general lighting and automotive applications. Other manufacturers are using Flip chip designs on a case per case basis.
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- Vertical LED structures are being increasingly adopted for a wide gamut of high power applications. Pioneered by Osram and Semileds, the design has now been adopted in many products by Cree, Lumileds, LG and others.
- The only commercial products based on an electrically
conductive substrates are CREE chips that are grown on SiC. However, CREE is increasingly adopting vertical LED design where the SiC epitaxial substrate is removed and replaced by a carrier substrate or submount (Silicon)
Copyrights Yole Dveloppement SA. All rights reserved.
Packaging Overview
High Power LED Packaging
Overview
Die Attach Interconnect Substrate
Thermal Management
Phosphor
(White LED only)
Eutectic Bonding Stud bump (Flip chip) Epoxy / Conductive Epoxy Ball/Wedge wire bond Ribbon Bonding
Substrate Only:
Ceramic, Metal, Silicon
Dispersion
Substrate
(Ceramic, Metal, Silicon)
High-Power LEDs include one or multiple chips. A very large gamut of packaging technologies is being used for High Power LEDs in order to handle the higher power density and manage the large amount of heat generated by the dice. There are no standard. Each design is unique in its form factor, die and packaging technology, choice of substrate materials, and the way those technology bricks are combined.
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Via through Die and/or Submount / Ceramic
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+ Si Submount
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Encapsulation
Encapsulation + 1 or 2 lenses Silicon or Epoxy
Conformal coating
Ceramic
Remote Phosphor
Wafer Level Packaging
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Packaging Overview
Singulation Equipment Market: Volumes
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Die Singulation
Substrates for mid-power LEDs
Trends
Technologies are well established and relatively standardized for low and mid power LEDs. However, large LCD backlight are driving some changes in the mid power category: Adoption of Multichip packages with 2 chips. Increase of the average power and light output, taking the chips used for this application closer to high power chips in term of thermal management solutions:
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Illustration of 2 die mid power chips (source: Samsung LED)
Picture of 2 die mid power chips (source: Assymtek) Example of evolution of lead frame structure for mid power chips used in TV backlight applications (source: Samsung LED)
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Packaging Substrates
High Power LED Substrate Market Penetration Forecast by substrate type
Yole Dveloppement
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Note: technology adoption rates for High Power (>1W) LED package only
2011
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Packaging Substrates
Interconnections:
Flip Chip Layout Principles and Technologies illustration: Lumileds Luxeon Rebel (1)
Contact to upper (p-GaN) level
Contact to lower (n-GaN) level
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Bump
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(c)
Pictures and drawings are by courtesy of System Plus Consulting (a) x-ray picture of substrate metal layers through LED die and bumps (b) Drawing of LED front (bottom) side layout (c) Drawing of LED cross-section with contacts (d) Picture of LED die front side
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(d)
Interconnect
Silicon Substrate and WLP for high power LEDs Main actors by wafer sizes (R&D or production)
Only a handful of players are currently working on silicon substrates, either on 6 or on 8 inch wafers. We expect silicon substrates to gain momentum as more operations are done at the wafer level, and on larger wafers. Thisway, silicon substrates will enable low cost assembly of high power LEDs.
6 inch wafers Unknown wafer size
Silicon Substrates
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8 inch wafers
12 inch wafers
neopac
Other WLP operations
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Wafer Level Packaging
Silicon Substrates and WLP
Example: VisEra technology (TW)
TSMC and subsidiaries VisEra technologies and Xintec technologies announced a High-Power LED packaging technology based on XX inch wafers Technology blends MEMS process and proprietary TSV techniques with wafer-level phosphor conformal coating and lens molding. Main Features: Mass production (low cost) Current capacity > XX M units/month Low thermal resistance (as low as 2C/W) CTE compatible
Currently available as a foundry service, TSMC might leverage on the platform to speed up its entrance into the LED industry.
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Courtesy of VisEra
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Wafer Level Packaging
Silicon in high power LED Packages
various uses
Component level Package level
LED
ESD/TVS Protection diode
As epitaxy base substrate (emerging in R&D)
As replacing substrate of sapphire for vertical diodes
Protection diode
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LED lens
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Protection diode LED substrate
Discrete component (most frequent case)
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Silicon package substrate (Visera, LG Innotek, tMt)
Silicon Silicon submount (Cree, submount Lumileds)
lens Protection diode, submount LED lens Protection diode LED lens
substrate substrate
substrate
In red: silicon parts
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