Lightscape Materials offers intellectual property (IP) in specialty phosphor technology, which Dow will add to its light-emitting diode (LED) technologies portfolio. Lightscape co-founders Gerard Frederickson and Yongchi Tian will join Dow?s LED Technologies team.

Major Lightscape Materials? investors included Wisepower and SRI International. Financial terms of the transaction were not disclosed. 

Phosphors are applied to or around LED chips for improved efficiency and color quality. They are implemented in display backlights and illumination LED fixtures. Also read: Phosphor trends for LED manufacturing

"The novel phosphor compositions developed by Lightscape Materials enable improved quality, reliability and output color of LED light-based systems," said Leo Linehan, global general manager for Dow Electronic Materials? Growth Technologies business. The phosphors will enable LEDs to create a wide spectrum of white light, with the color tuned for the desired application.

Dow formed its LED Technologies business segment in October 2011. Its portfolio includes metal-organic chemical vapor deposition (MOCVD) precursors for LED manufacturing, photoresists and related ancillaries for lithographic processing, metallization processes for electroplating, and pads and slurries for chemical mechanical polishing/planarization (CMP). In March, Dow opened an R&D center in Seoul, South Korea, with a focus on organic LEDs (OLEDs).

Dow (NYSE: DOW) is a wide-ranging science and technology company offering specialty chemicals, advanced materials, agrosciences and plastics for electronics, water, energy, coatings and agriculture. Dow Electronic Materials is a global supplier of materials and technologies to the electronics industry, serving the semiconductor, interconnect, finishing, photovoltaic, display, LED and optics markets. Dow Electronic Materials has manufacturing and research facilities in the US, Europe, China, Taiwan, Japan and Korea. 

More information about Dow can be found at http://www.dow.com.
Wisepower (KOSDAQ: 040670) is a diversified business in batteries, wireless charging solution and LED lighting. More information about Wisepower can be found at http://www.wisepower.co.kr.

SRI International, a nonprofit research and development organization, performs sponsored R&D for governments, businesses, and foundations.

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The new headquarters should be completed in H2 2013. The additional ?infrastructure and scale? were necessitated by Kulicke & Soffa?s growth over its 12 years in Singapore, said Bruno Guilmart, president and CEO. Guilmart praised Singapore?s proximity to the company?s semiconductor packaging customers and supply chain, and the encouraging work environment. Tan Choon Shian, Deputy Managing Director, Economic Development Board, called the expansion a ?significant commitment? for Singapore?s precision manufacturing environment.

Also read: How the road to Singapore accelerated manufacturing in China

Kulicke & Soffa (NASDAQ: KLIC) makes semiconductor and light-emitting diode (LED) assembly equipment, offering ball bonding and die and wedge bonding tools. Learn more at www.kns.com.

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While utilization rates are still relatively low in LED fabs, many chipmakers are reluctant to convert all of their backlighting-specific (BLU LEDs for display applications) LED tools to lighting-specific production, because they value yields honed for a specific design. Chipmakers told Barclays that they do not want to reconfigure metal-organic chemical vapor deposition (MOCVD) tools unless they are confident that this backlighting-specific production will no longer be needed. This suggests that anticipated LED lighting demand in H2 2012 and beyond will require more MOCVD tool orders, even without higher capacity utilization rates in LED fabs. Gradually improved MOCVD capex, in Q3 2012 and beyond, will be supported by a steady stabilization in LED supply/demand as 2013 approaches.

Barclays observed that LED chips still compete based on price, even among the Tier 1 LED makers, and further cost reductions are needed if margins are to survive. LED component price declines did moderate to an extent relative to last year?s price cuts, but the aggressive pricing trend continues, driven in part by end customers leveraging Tier 3 quality price points in China against Tier 1 and 2 LED makers. Until LED makers reach 80%+ effective yields in the fabs, the distribution of LEDs per run is fairly wide. Chips that do not meet their application?s specs are dumped on the market at a much lower price. Indeed, even in lighting-grade LEDs, there is ?no rationality for price points,? according to 1 Tier-1 supplier. The good news for LED revenues is that unit volume growth is offsetting the price cuts.

The quality barrier between Tier 1 and Tier 2/3 LED suppliers continues to hold, with only ~10 LED makers that can reach 100lm/W efficacy levels in mass production, and meet Energy Star, UL, etc., specifications. In step with the luminous efficacy improvements at the chip level, system-level efficacy also continues to increase, with various troffers and luminaries already approaching 100lm/W. Korean LED makers are considering leveraging BLU LEDs for some lighting applications, like linear lighting and troffers, because specifications are similar. As a result, Samsung is becoming a major threat to Tier-1 LED suppliers, longer term, as it focuses on quality.

Also read: As LED patents run out, supply chain value will shift downstream

With LED lifetimes approaching 50K hours, LEDs are no longer the predictors of the lifetime of the full system, and the lifetime of the other components is becoming more prominent. Despite various certifications available, data on the lifetime and reliability at the total system level is still fairly limited.

While still in the early stages of development, OLED lighting was also being exhibited by several suppliers, with Philips and OSRAM appearing to be at the lead from an efficacy and product quality standpoint. Philips? OLED lighting panels reached 25lm/W this year, with the company aiming for 60lm/W next year, driven by new developments in OLED materials (Philips using RGB stack with combination of phosphorescent and fluorescent materials); new developments in the glass substrate (adding reflective element to the glass composition); and advances in the deposition and processing technology. However, while reaching 60lm/W efficacy would be a big breakthrough, the key from there would be lumen maintenance, which is still very low for the OLED lighting panels currently available on the market. And while some companies suggested that OLED lighting is now moving from a designer/architectural application to a high-end lighting application, based on the product specs and the pricing, Barclays puts OLED lighting ~5-7 years behind LED lighting.

This year?s Lightfair was ?almost entirely focused on LEDs,? said Barclays analysts. While LED dominance in new products at the booths is not yet indicative of end market penetration, it highlights the inevitability of LED lighting adoption in the coming years. Most lighting manufacturers and suppliers and LED makers alike see 2012 as a year of steady, strong LED lighting demand growth, though not yet an inflection. The biggest ramp in demand remains in segments where lighting is on for longer than 8 hours per day (streetlights, gas station canopies, retail, hospitality, warehouses). This is aided by the Federal Recovery Act spending on retrofitting public fixtures. Membership in the Solid State Street Lighting Consortium -- a Department of Energy (DOE)-sponsored consortium of cities and municipalities looking to upgrade their lighting systems to energy-efficient solutions -- has expanded to ~350 members from less than 100 last year. Payback periods for LED installs are compressing -- for outdoor lights, LED systems have gone from 50-60% more expensive than non-LED lights last year to ~30-50% more. The payback for replacing non-LED luminaires in many applications is currently 2-5 years, sufficient to ensure funding for many commercial and industrial users. Utility rebates and government subsidies offered in various regions enhance paybacks further.

Many companies at Lightfair indicated that advances in LED chips and components, especially with regard to high efficacy, have lowered the cost of other components in a lighting system, driving down costs.

Learn more about Lightfair at http://www.lightfair.com.

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GE?s 27-watt Energy Smart LED bulb is in a standard ?A-19? bulb shape, with 1600 lumens (60 lumens/watt), uniform omnidirectional light distribution, 3000K color temperature, and 25,000-hour life rating (22.8 years at 3 hours per day).

The bulb is manufactured with a proprietary synthetic jet technology enabled by Nuventix? collaboration. Nuventix? oscillating membrane, called a synthetic jet (an alternative to a fan), cools the LED chips and fits within the form factor of the A-19 bulb shape. Each subsystem -- optics, electronics, thermals -- must be ?designed for miniaturization and cooperative performance,? says Steve Briggs, general manager of LED systems, GE Lighting. This technology provides a ?clear path? to higher light levels and more energy efficiency.

The bulb will be in stores in 2013, and is debuting at LIGHTFAIR International in Las Vegas this week. GE?s existing portfolio of LED bulbs includes a 13-watt LED (60-watt incandescent replacement) and a 9-watt LED (40-watt incandescent replacement), as well as others in various shapes, wattages, and colors.

Nuventix provides thermal management for electronics. Visit www.nuventix.com.

GE Lighting develops energy-efficient solutions to light commercial, industrial, municipal and residential settings. For more information, visit www.gelighting.com.

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Quantum dots produce colors based on the size of the quantum dot particles -- shifting from red to blue as the nanocrystal shrinks. Ultra-small quantum dots, containing 60-70 atoms, emit white instead of monochromatic light. Almost all of the atoms of these QDs are on the surface, making white-light emission ?intrinsically a surface phenomena,? said Sandra Rosenthal, the Jack and Pamela Egan Chair of Chemistry, who directed the research.

The high efficiency is comparable to some commercial phosphors, said Rosenthal. It could be improved even further. Rosenthal expects white-light quantum dots to be used in some special lighting applications.

Current white-light LEDs offer 28-93 lumens/watt. If the enhanced quantum dots were combined with the most efficient ultraviolet (UV) LEDs, it would register a luminous efficiency of about 40 lumens/watt, said James McBride, research assistant professor of chemistry, who has been involved in the research from its inception. As UV LEDs are improved, the hybrid LED/QD combo would gain higher efficiency.

Instead of creating a material ?shell? around the QDs, the researchers treated quantum dots with metal (acetate) salts, following a lead from University of North Carolina research. The salts produced an 8% brightness increase. Once the researchers determined that acetate salts had an effect, they tried acetic acid, which binds to quantum dots. The acetic acid treatment increased the quantum dots fluorescent efficiency to 20%. From there, researchers tried other members of the carbocyclic acid family. Formic acid, the most acidic and simplest, pushed the efficiency up to 45%.

The brightness increase shifted the peak of the color spectrum of the quantum dots slightly into the blue, which is a light spectrum many consumers find unpleasant with today?s LEDs. The researchers will use other methods to correct the color balance.

The researchers? next step is to test different methods for encapsulating the enhanced quantum dots.

Other contributors to the study include graduate students Teresa E. Rosson, Sarah M. Claiborne and undergraduate research student Benjamin Stratton, who is now at Columbia University. The research is described online in the Journal of the American Chemical Society. The work was supported by a grant from the National Science Foundation.

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SunSun Lighting eliminates the performance and cost trade-offs of current LED lighting technology by offering a complete LED system, including power electronics, housing, packaging, and optics.

"SunSun is committed to shifting the lighting industry to solid state lighting. We offer the world's first LED lamps that maximize both luminous efficacy and color rendering with the lowest cost. This capital will be used to expand our manufacturing capacity, sales and marketing efforts, and research and development," said SunSun Lighting Founder and CEO Jianning Sun.

The company's patented PowerXplore technology attains the highest AC/DC conversion rate of 92%, compared to the 85% conversion rate of the nearest competitor. By innovating at the system level, SunSun achieves both high performance and low lifecycle cost, significantly broadening the potential applications for LED lighting technology.

The company will debut its latest product, the MR16 LED bulb, which is universally compatible with AC/DC 12V and all transformers today in Booth 225 at the LIGHTFAIR International architectural and commercial lighting tradeshow and conference.

"There is a huge market for solid state lighting," said Sonny Wu, the co-founder and a managing director of GSR Ventures and Chairman of the Board for SunSun Lighting. "It could be a $300 billion market globally in three years. GSR incubated the company in 2010 when Mr. Sun had an innovative idea of designing the LED lightbulb with a revolutionary new architecture. We were the sole investor in the $10 Million Series A round for SunSun, and continue to support the company given the phenomenal growth opportunities we see," he added.

"SunSun Lighting stands out from the many LED companies we have seen over the years," said Bandel Carano, managing partner for Oak Investment Partners. "We are convinced that SunSun has superior architecture and technology and is well-positioned to scale. Furthermore, we are pleased to partner with GSR on another investment in China, strengthening our strategic relationship with the firm. The combination of GSR's knowledge of the Chinese market, Oak's deep domain expertise in clean energy, and SunSun's technology and leadership team, will help the company realize its tremendous potential."

"We believe strongly in SunSun's management team, including CEO Sun, and his senior research and development executives," said Allan Kwan, a China-based advisor for Oak. "The team has assembled a compelling value proposition -- a superior silicon-based technology approach, a powerful customer base of world-renowned lighting companies, and a world-class manufacturing facility and process," Kwan added.

The global lighting market has shown it is ready for LED technology that meets or exceeds the performance of conventional bulbs while lowering cost. The U.S. Department of Energy estimates that switching to LED lighting over the next two decades could save $120 billion in energy costs in the U.S. alone.

SunSun Lighting is a cutting-edge manufacturer of LED lighting products, based in China's Jiangsu Province. Founded in 2010, SunSun is committed to shifting the lighting industry to solid state lighting. SunSun eliminates the performance and cost trade-offs of current LED lighting technology by offering a complete LED system, including power electronics, housing, packaging, and optics. By innovating at the system level, SunSun achieves both high performance and low lifecycle cost, significantly broadening the potential applications for LED lighting technology. www.sunsunlighting.com.

GSR Ventures is an early-stage venture capital firm focused on building world-class technology companies in China. The firm invests primarily in the Internet, wireless, green technology and semiconductors sectors. Founded in 2004, GSR has 50 companies in its portfolio and more than $1 billion under management. SunSun Lighting is the firm's tenth investment in energy efficient companies. For more information, visit www.gsrventures.com.

Oak Investment Partners is a multi-stage venture capital firm and a lead investor in the next generation of enduring growth companies. Since 1978, the firm has invested $9 billion in nearly 500 companies around the world, earning the trust of entrepreneurs with a senior team that delivers steady guidance, deep domain expertise and a consistent investment philosophy. The firm's five major growth sectors of focus are information technology, internet and consumer, financial services technology, healthcare services and clean energy. For more information, visit www.oakvc.com.

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Figure 1. Packaged LED price trends. SOURCE: SEMI.

?In a commodity market -- and we think this is a commodity market -- the guy with the lowest cost structure wins,? notes Jed Dorsheimer, managing director, equity research, lighting & solar, Canaccord Genuity. ?And yield is by far the most important driver of costs.? With best industry net yields still at some 75-80%, and the majority around 50%, there?s plenty of room for improvement, particularly in automating the post epi processing, by using semiconductor industry style automation, steppers, and improving the lift-off, thinning, dicing and sorting processes. Last year?s 50% drop in prices really focused people?s attention on cost structure, and is speeding up the investment in automating these back end of line (BEOL) processes.

Table. Summary of LED package price and performance projections.

Notes: Though cost and especially efficiency of LED lighting has improved impressively recently, there are still major improvements necessary to meet the aggressive target price per lumen output needed for wide adoption according to the industry consensus roadmap put together by the US Department of Energy. It figures the cost for warm white packaged LEDs was about $12.50/klm as of last year, and targets a drop to $5.10/klm by next year, to stay on target for $2.00/klm by 2015. Projections for cool white packages assume CCT=4746-7040K and CRI=70-80, while projections for warm white packages assume CCT=2580-3710K and CRI=80-90. All efficacy projections assume that packages are measured at 25°C with a drive current density of 35 A/cm²; Package life is approximately 50,000.(Source: US DOE Solid State Lighting R&D Multiyear Program Plan, April 2012)

The choice of substrate material is naturally the first driver of yield, where it may turn out that high-cost, homogenous gallium nitride (GaN) substrates with very low defect density and potentially high yield could turn out to be a low cost choice, argues Dorsheimer. Silicon substrates seem like a low cost alternative, but even if fully depreciated equipment brings the typical 20% capital cost to zero, and low substrate costs bring the typical 15% substrate cost to zero, lower yields could still make GaN on Si more expensive than sapphire or SiC.

The potential for GaN and Si substrates

LED devices made on silicon now look likely to be able to match the performance of conventional devices on sapphire, reports Virey, as work at a number of labs around the world is closing the performance gap. So the crucial issue is really the cost savings from being able to use highly efficient 8-inch silicon processing equipment. Yole cost simulations show a 50% reduction in die cost is possible, and some companies project as much as 75% savings, at least compared to smaller diameter sapphire, depending of course on yield, on how much the producer has to invest in new facilities, and on how much retrofit is needed to convert a CMOS fab to LED production. With the biggest impact on yields in epi now apparently not from dislocation defects but from bowing during the metal organic chemical vapor deposition (MOCVD) process, fine tuning the thermal properties during epi could potentially bring significant improvement.

But it does open the possibility of an almost fabless model for LED makers who could produce in CMOS foundries. And it could certainly change the industry supply equation. ?One CMOS fab probably has enough capacity for the world?s supply of LED die,? notes Virey. GaN-on-GaN should have better yields from less bowing, and has advantages for being able to inject more current to get more light out of a smaller chip area, for high current density applications. But with the leading conventional LEDs on sapphire or SiC now up to 200lm/W efficiencies, closing in on the theoretical limit, the 5 to 10% increase in performance possible with the GaN substrate may not be worth the 10x higher substrate cost. Here again, it?s just a cost game where yield is the critical parameter.

Figure 2. LED chips made on a 2" silicon wafer. SOURCE: Lattice Power.

Lattice Power pushes toward mass production with GaN-on-Si

Lattice Power reports it is now selling commercial LED die from volume production runs of several hundred 2? silicon wafers a day from its Jiangxi, China, fab, and aims to transition to 6? wafers within twelve months. ?We?re not in R&D mode anymore, we?re pushing towards mass production,? says CTO Hanmin Zhao. He reports performance, cost and yields in the 2? silicon are similar to 2? sapphire, and reliability and life test have so far shown results similar to sapphire.

Zhao says the company?s solution for designing and then growing the multi-layer buffer layers to counter the lattice and thermal mismatch seems to transition fairly well to 6? wafers, where the advantage of silicon would of course be much more significant. It?s looking at 6-inch because the tools would be affordable, while it needs a partner with an idle 8-inch IC fab to make production on 8-inch silicon economical with the more expensive tool cost, and there are not many idle 8-inch fabs in China. Zhao figures that except of course for the MOCVD equipment, some 70-80% of the CMOS tools could be used with only minor modification.

These speakers will join other industry leaders from Cree, Everlight Electronics, Soraa, Seoul Semiconductor, GT Advanced Technologies, EVGroup, Laytec and more to discuss the potential of disruptive technologies and best options for improving manufacturing yields in LED manufacturing at Extreme Electronics (South Hall) at SEMICON West 2012, July 11, in San Francisco.

And don?t miss the US DOE SSL Manufacturing R&D Workshop 2012, June 13-14 in San Jose, CA, www1.eere.energy.gov/buildings/ssl/sanjose2012.html

SEMI is online at www.semi.org.

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Samsung Electronics has launched its first direct LED-backlit TVs, the EH series, in the US, and LG Electronics will follow soon with its LS3400 series.

Also read: Cheaper LED backlights require LED, plate materials changes

LED-backlight penetration in the LCD TV market has been lower than expected, especially in the entry/mainstream segment: 9 points lower than DisplaySearch?s 2011 forecast overall. LED technology for backlights was more expensive than anticipated, limiting consumer purchases. Edge backlight designs were not able to meaningfully reduce the cost premium over CCFL backlighting, though the concept has helped TV makers maintain revenues against a severe market overall.

Figure 1. Trends for LED-Backlit TV Price Premium and Penetration. SOURCE: Q1?12 Quarterly LED Backlight Report.

Now, TV makers are focusing on new types of direct LED backlighting to capture a broader swath of consumers, adding value to the entry/mainstream segment just as edge LED backlighting added value to the premium segment TVs. At the same time, the CCFL industry is experiencing shortages in rare earth metals, stressing already-tight cost structures. There are fewer new CCFL-backlit models this year. DisplaySearch expects the price premium for direct LED-backlit TVs over CCFL-backlit TVs to decrease quickly.

In the Q1?12 Quarterly LED Backlight Report, DisplaySearch forecast that LED backlighting, with help of low-cost direct designs, will achieve 100% penetration of the LCD TV application by the end of 2014, killing CCFL designs. Low-cost direct LED backlighting (~20% share in 2014) will take share away from CCFL backlighting, not from edge LED backlighting. At the same time, edge LED backlighting will continue to incrementally replace CCFL backlighting. Low-cost direct LED backlighting will saturate after CCFL-backlit TVs leave the market and maintain its market position in the entry/mainstream segment.

Figure 2. Forecast for TV Panel Shipments by Backlight Type. SOURCE: Q1?12 Quarterly LED Backlight Report

These changes to the TV market will affect the market for CCFL in other displays, such as monitors. In Q1?12, revenue from CCFL for TVs is estimated to be 81% of total CCFL revenue, as reported in the Q1?12 Quarterly LED Backlight Report. It is not an exaggeration to say that the current CCFL supply chain depends solely on the shipments of TVs. If demand for CCFL in TVs disappears, then it will be hard for the CCFL industry to maintain its supply chain, because the other applications account for only 19% of total demand. Therefore, we forecast that after CCFL-backlit TVs leave the market, most CCFL-backlit monitors will face EOL as well.

Learn more at www.displaysearch.com.

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Carsem has begun assembling and qualifying high-brightness silicon-substrate LED arrays and will ramp high-volume, full turn-key manufacturing services, including electrical testing, laser mark, and tape-and-reel, in early 2012.

To enable standard mass production, Carsem deployed matrix substrate design; auto die attach, wire bond, and high reflection coating dispense; compression molding through an automold system; substrate-mapping; and bin sort per test mapping on the LED packages.

Carsem?s experience in turnkey semiconductor packaging enabled its LED customers to bring products to market faster, based on high-density, high-volume packaging technology, said Albert Law, Carsem VP of worldwide sales and marketing. Knowledge derived from semiconductor materials, processes, and equipment enhanced the ?manufacturability and efficiency? of the customer?s HB-LEDs, added L.W. Yong, Carsem CTO.

Also read: LED cost reduction to come from manufacturing

Carsem provides turnkey packaging and test services to the semiconductor industry. Website: www.carsem.com.

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Intematix also offers A Lamp reference designs for these systems.

Intematix?s ChromaLit remote phosphors separate the phosphor substrate from the blue LED instead of coating the LEDs with phosphor directly. This reportedly reduces LED costs by 25% and improves color matching and light quality.

ChromaLit Contour exceeds Energy Star and China Quality Certification lighting requirements with uniform, glare-free and diffuse light; 330° lighting distribution; standard color rendering options up to CRI 90; choice of color temperature from 2700K to 5000K; and color matching. Any blue LED can be used with the remote phosphor architecture.

ChromaLit Contour in 60W, 75W and 100W incandescent equivalent configurations can be seen at LIGHTFAIR in Las Vegas, May 9 -11, booth 2949.

Intematix Corporation is a materials developer making customizable, patented phosphors and remote phosphor components for high-quality, energy-efficient LED lighting. To learn more about the company, please visit www.intematix.com.

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LM-79 has become a requirement for solid state lighting products, said Mark McClear, director of global applications engineering, Cree. In addition to LM-79, TEMPO 24 testing includes binning and color point evaluation, chemical compatibility, and TM-21 lifetime projection tests to ensure reliability in LED luminaires.

Also see: Luminus Devices accredited to LM-80 test standard and UL authorized for LED testing to Zhaga standards

Cree currently provides TEMPO Services out of its Durham, NC and Santa Barbara, CA centers. The Cree Durham Technology Center has been accredited by The National Voluntary Laboratory Accreditation Program (NVLAP), which ensures that TEMPO measurements are performed according to IES-approved methods for the electrical and photometric measurements of LED lighting. NVLAP accreditation signifies that a laboratory operates in accordance with NVLAP management and technical requirements pertaining to quality systems, personnel, accommodation and environment, test and calibration methods, equipment, measurement tractability, sampling, handling of tests and calibration items, and test and calibration reports.

Cree laboratories also work to American National Standards Institute (ANSI) and National Institute of Standards and Technology (NIST) requirements.

Cree develops and produces lighting-class LEDs, LED lighting, and semiconductor products for power and radio frequency (RF) applications. Learn more at www.cree.com.

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This month, I'd like to put on my Associate Publisher hat and tell you about some of the changes Solid State Technology has recently made, and what we can do for you.

For starters, you may have noticed a change to our logo on the front of the magazine and on our website, with a bit more empahsis on the "Solid State" part of it. We did this in part to call attention to our roots, going back 54 years to 1958. The magazine actually started out as "Semiconductor Products" and then became "Semcionductor Products and Solid State Technology" in 1962, and then "Solid State Technology" in 1968. It was cool then, and it's still cool today!

Another reason for the change is that we have broadened our focus beyond mainstream semiconductor manufacturing to include more on advanced packaging, MEMS, LEDs, displays and other types of electronics such as biomedical devices, sensors and power electronics. Each of these has evolved to the point where new and unique process technologies and materials are required, and our goal is to keep you informed of the latest advances.

Most of you are reading this magazine in a digital format, perhaps on a mobile device. In October of last year, we launched a new design tailored for easy readability in the digital format.

We also made substantial improvements to our website, www.solid-state.com, to provide easier navigation, better search, faster load times, better SEO and greater ease-of-use with mobile devices. Five channels (each with topic centers) focus on Semiconductors, Packaging, MEMS, LEDs and Displays.

We have a strong line-up of Solid State Technology newsletters now including: WaferNEWS, LED Manufacturing News, Displays Digest, Advanced Packaging News, MEMS Direct and, every weekday, The Daily Pulse (sign up on the web).

Each month, we deliver this magazine to 40,000 people around the world. If you include SST China and SST Taiwan, each of which includes translated and original content, that number is well over 57,000 (57,301 to be exact).

What's important to note here is that the people reached by the magazine is a very different audience than that of our website (about 100,000 unique visitors/month) and newsletter subscribers (45,000). This gives us a total worldwide reach of 233,286 people.

In addition to the magazine and the website, we produce The ConFab, an exclusive invitation-only event coming up next month in Las Vegas (I'm the conference chair), webcasts, technology guides, videos, and an online Buyer's Guide. On our website, you'll also find white papers, podcasts, blogs and a bunch of other stuff (whew, if you're tired of reading this, think about me!).

Industry Forum columns conclude with a call to action, so here it is: Think about how you might contribute material. We're always looking for good feature content ? you'll find our "roadmap" in our editorial calendar ? as well as business and technology news, blogs, columns, book reviews, conference reports, case studies, how-to articles, new products.. you name it. We're happy to work with you to see what makes the most sense.

Any questions? Contact me for editorial matters, at peters@pennwell.com, and, for advertising and sponsorships, contact Kerry Hoffman at kerryh@pennwell.com.

Solid State Technology, Volume 55, Issue 4, May 2012

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?Lumichip has an increasing client base in Europe and Scandinavia,? noted Dr. Juha Rantala, chairman of the Lumichip group. Lumichip?s new global commercial service center will support all technical aspects and product sales for LED customers.

The company?s investments in Finland also include research, from basic LED component to advanced light engine technology design, and production of custom-designed LED light systems. ?Our chip and package design and manufacturing will continue in Asia, but we wish to leverage the leading edge electronics and systems development expertise available in Finland into our new products and services,? Dr Rantala said.

Lumichip?s new European Micronova site is within the Finland National Research Infrastructure for micro- and nanotechnology and its modern facilities include 2600m2 of cleanrooms and processing lines for silicon CMOS, MEMS, III-V optoelectronics and various thin film devices. The available technologies and expertise of the center will be part of Lumichip?s technology roadmap for better LED devices and systems with intelligence, reliability and cost efficiency.

Learn more at www.lumichip.com.

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Child has been with TA Associates Inc., a Boston-based private equity firm that manages over $16 billion in capital, since 1982, and is currently a senior advisor. He sits on the boards of Finisar Corporation, IPG Photonics, and FreeWave Technologies. While at TA, he has served as a director of 16 public companies including AST Research, Cadence Design Systems, DH Technology, Eagle Test Systems, Fargo Electronics, Network General Corporation, Novellus Systems, and Sonic Solutions. Prior to joining TA, Child worked for Rolm Corporation as a product manager, The Boston Consulting Group as a consultant, and Hewlett-Packard as a production engineer.

Child holds a bachelors of science in electrical engineering from the University of California at Davis and an M.B.A. from the Stanford Graduate School of Business.

Child combines extensive knowledge of this industry and of Ultratech itself, noted Ultratech chairman and CEO Arthur W. Zafiropoulo.

Ultratech Inc. (UTEK) designs, manufactures and markets photolithography and laser processing equipment for bump packaging of integrated circuits and high-brightness LEDs (HBLEDs). Ultratech developed laser spike anneal technology, which increases device yield, improves transistor performance and enables the progression of Moore's Law for 45-nm and below production of state-of-the-art consumer electronics. Visit Ultratech online at www.ultratech.com.

The ChromaLit series uses a phosphor composite substrate separated from the blue LEDs instead of coating them directly. This enables use of a blue LED engine instead of binned white LEDs. The technique reportedly eliminates glare, offers diffuse light, increases efficacy up to 30%, and improves color rendering and light quality.

ChromaLit XT targets higher-intensity light applications that require high lumen output in a small form factor, such as spotlights and floods. Users can see up to 65% lower cost per lumen and enhanced off-state neutral color when compared to conventional remote phosphors that are yellow, Intematix reports. ChromaLit XT is optically treated to maintain an off-state neutral appearance when the LED light is off. ChromaLit XT meets UL standards and is offered in a range of CCT and CRI options.

ChromaLit XT will be on display for the first time at the Light+Building trade fair in Frankfurt, Germany from April 15-20 and again at LIGHTFAIR in Las Vegas, May 9-11.

Intematix Corporation is a materials development company providing customizable, patented phosphors and remote phosphor components for LEDs. Learn more at www.intematix.com.

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Testing occurred at standard room temperature and 350mA. Cree?s previous R&D industry record was 231 lumens/watt.

The R&D LED uses elements of Cree?s SC³ Technology Platform, which is used in Cree?s XLamp LEDs. SC³ combines Cree?s advanced silicon carbide (SiC) technology, with an advanced LED chip architecture and phosphor, and a new LED package design.

Cree makes LEDs and LED lighting products, as well as semiconductor products for power and radio frequency (RF) applications. Internet: www.cree.com.

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Also read: LED test standards, packaging material challenges

These grades retain more than 98% of initial light transmission when exposed to a temperature of 130°C for more than 5,000 hours. At more typical heat exposure in the range of 90-110°C, the transmission retained is even higher.

They also provide improved light transmission (10 units better, compared to competitive products) after heat aging at low wavelengths typical of LED systems, according to the company.

Customers have a choice of flow characteristics for various LED applications, including automotive light guides and inner lenses and general lighting lenses. They also meet the UL 94 V-2 rating at 0.8mm and glow wire flammability index (GWFI) 850C at 1mm, according to the International Electrotechnical Commission (IEC) 60695-2-12.

The resins complement SABIC?s existing Lexan LUX resins: non-chlorinated, non-brominated FR resins that meet the UL 94 V-0 standard at 1.5 mm in all colors.

Saudi Basic Industries Corporation (SABIC) is a top petrochemical company producing polyethylene, polypropylene, advanced thermoplastics, glycols, methanol and fertilizers. Its Innovative Plastics strategic business unit supplies engineering thermoplastics including thermoplastic resins, coatings, specialty compounds, film, and sheet. Innovative Plastics is a wholly owned subsidiary of Saudi Basic Industries Corporation (SABIC). Learn more at www.sabic-ip.com.

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A technology has been developed that allows AlN to be sintered at lower temperatures. This allows the material to be sintered and flat fired in a continuous furnace very similar to furnaces used for alumina.

Packaging requirements for high brightness LED (HBLED) technology is pushing the current material envelop for both low cost and high thermal performance. The desire to shrink package size is driving LED substrate requirements toward higher and higher heat dissipation. And the commercial imperative to decrease the $/Watt figure of merit for light output is putting cost pressure on the LED packaging technology to utilize lower cost substrate alternatives.

HBLED devices are bonded to a ceramic "tile" that consists of a ceramic substrate that has been metallized with thick-plated copper. Connection between the top surface with the active device and the backside, which is surface-mounted to a high thermal conductivity metal core printed circuit board, is accomplished with Cu-filled vias. Thus heat conduction from the active device occurs through both the Cu vias and the ceramic. The ceramic material provides electrical isolation between the different polarity inputs that drive the LED.

Traditionally, 96% Al2O3 has been used as the ceramic substrate in HBLED applications because of its low cost and good mechanical stability. However, with a thermal conductivity of only 20 W/m-K, alumina does not contribute significantly to heat transport in the tiles. This brings in the opportunity for using other ceramic materials with higher thermal performance such as AlN or Si3N4.

The downfall for both of these alternatives has been much higher cost than alumina.

Aluminum Nitride

Aluminum Nitride (AlN) is a polycrystalline, high melting temperature (refractory), ceramic material with an advantageous set of properties for die level packaging of high brightness LEDs and power semiconductors. These critical properties include:

? Good electrical insulation

? High thermal conductivity

? High flexural strength

? Stable up to very high temperature

? Able to be laser drilled, metallized, plated and brazed

A more detailed list of properties is shown in Table 1 below.

As power densities of semiconductor devices increase, the need for packaging to remove generated heat increases, particularly for devices such as LEDs, which are sensitive to increasing temperature. AlN, which has a thermal conductivity that is 8-9 times higher than competitive materials such as Al2O3, becomes an excellent technical solution to increasing thermal demands on first level packaging materials.

Applications with high and increasing thermal demand include: RF power components for cellular infrastructure, HBLED, power semiconductors for motor control, packaging for highly concentrated photo-voltaic installations, and packaging for semiconductor lasers used in telecommunications.

AlN ceramic substrates are typically 15 to 60 mils thick, and up to 4.5" square (larger for some specialized applications). These substrates are fabricated using conventional ceramic processing technology. A typical fabrication sequence is given in Table 2 below.

As evident from the brief discussion above, AlN has a range of very beneficial properties for high thermal demand applications. However, there is one very key drawback of AlN which has limited its utilization. The key issue is the cost of AlN substrates relative to lower performance materials such as alumina. Typically, AlN costs 5-7 times more than alumina on a cost/square inch basis.

Below is a list of the key contributors to this higher cost structure:

1. Currently available AlN powder is approximately 20 times more expensive than alumina powder of comparable quality (purity, particle size).
2. AlN tape must be fired in a non-oxidizing atmosphere. This means that binder removal, which is typically done through oxidation, must be done in a separate furnacing step (at a temperature well below the sintering temperature). A thick film continuous furnace can be used. For alumina, binder removal can be accomplished in the sintering furnace in one furnace step.
3. AlN is sintered in a batch furnace with much lower throughput than continuous furnaces used for alumina. In addition, these batch furnaces are constructed using Mo and W metal heat shields and heating elements because of the extremely high sintering temperatures (>1800°C), so the overall furnace cost is very high.
4. AlN can also be sintered in graphite batch furnaces. Though lower capital cost than W furnaces, the sintering fixtures for this type of furnace are very high cost and the throughput is still low due to batch processing. Also, the interaction of AlN with the carbon containing atmosphere is a graphite furnace must be limited to produce high quality product.
5. The considerations of furnace cost and low throughput for sintering are also a factor for flat fire, so there is essentially a "double hit" for using batch processing.
6. Alumina can be processed in an aqueous environment. This makes the tape fabrication less expensive than the AlN process which must utilize non-aqueous solvents. This is a significant factor for tape casting.

The focus of this article will be to discuss a new technology that has been developed at CMC Laboratories, Inc. which addresses items 3, 4 and 5 in the list above. This new technology allows AlN to be sintered at lower temperatures which allows the material to be sintered and flat fired in a continuous furnace very similar to furnaces used for alumina.

HBLED grade AlN

Table 3 below compares key properties for the low temperature sintered, lower cost "HBLED Grade" AlN compared to the standard, high temperature sintered, higher cost material that is currently commercially available.

It is clear from this graph that all of the properties are very similar, except that the thermal conductivity of the HBLED grade material is about 24% lower, but is still 6+ times higher than alumina. This makes the HBLED grade material suitable for all but the highest thermal demand applications for AlN.

HBLED grade AlN is made with the same basic processing steps outlined in Table 2 that are used for the high temperature material. The key difference is the sintering additives which allow the material to densify at 1675-1690°C as compared to the conventional 1820-1835°C. Tape binder formulations, tape casting conditions and the binder burn out process are also the same as, or very similar, to conventional material.

Figure 1. Low temperature sintered AlN substrate.

Fig. 1 shows a picture of a 4.5" x 4.5" x 20 mils substrate made from HBLED grade material that was fired at 1690°C in a nitrogen gas atmosphere with a hold time at sintering temperature of 3 hours.

Sintering aids for AlN ceramics perform two key functions: (1) they form a liquid phase at the sintering temperature which increases the rate of densification ("Liquid Phase Sintering" process); and (2) they getter oxygen from the AlN grains during sintering. Since the oxygen content of the AlN grains controls AlN's thermal conductivity, effective oxygen gettering is key to achieving the highest possible thermal performance.

The sintering temperature must be high for two reasons for the. First, the temperature must be high enough to melt the additive phase to form a liquid which enhances the rate of sintering by orders or magnitude. Second, the temperature must be high enough so that oxygen can diffuse out of the AlN grains during sintering to enhance the thermal conductivity of the AlN ceramic.

There is a third critical requirement for the additive phase during AlN sintering. While a liquid, the Y-Al-O phase will completely surround each AlN grain. If we define a wetting angle between the AlN and Y-Al-O measured at the 3 grain junctions, the microstructure has a very low wetting angle that is less than 60?. This type of microstructure is shown in the SEM micrograph in Fig. 2a. The dark grains in this figure, which are about 10 microns large, are the AlN. The bright phase is the Y-Al-O.

There are two critical performance issues with a wetted microstructure. First, because AlN fracture is inter-granular, the presence of a Y-Al-O phase between the grains lowers the tensile strength of the ceramic by a large factor. The second problem is that a wetted microstructure results in Y-Al-O covering large portions of the surface of the substrate. This reduces the consistency of AlN metallization processes.

So a key requirement for the oxide second phase during AlN sintering is that the oxide phase de-wet the ceramic grains during the later stages of the sintering process so that the final microstructure will have a de-wetted Y-Al-O phase as shown in the micrograph in Fig. 2b.

? These same basic considerations for sintering of high temperature, conventional AlN are relevant to designing a low temperature sintering process:

? The sintering additive must melt at the sintering temperature to facilitate liquid phase sintering kinetics.

? The temperature must be high enough for oxygen to diffuse out of the AlN grains during sintering. This consideration puts somewhat of a lower limit on how low AlN can be sintered to produce high thermal conductivity.

? The liquid phase must de-wet from the AlN grains after densification to form a de-wetted microstructure and thus high flexural strength.

? This de-wetting is also required to produce ceramic with high electrical resistivity

Figure 3. Microstructure of AlN, sintered at 1675°C.

Fig. 3 shows the microstructure of a low temperature formulation that was fired at 1675C. This has a modified sintering additive package which will melt at much lower temperature than the conventional Y-Al-O additives, but still has a strong chemical driving force to getter oxygen from the AlN grains.

As in the previous micrographs, the dark grey areas are the AlN ceramic grains, about 3-5 microns in size, and the bright areas are the oxide sintering additive phase.

Furnacing considerations

The motivation for developing an AlN formulation that sinters below 1700°C is the new furnace options that this lower temperature opens up. At 1700°C or below, a continuous tunnel kiln can be utilized. This furnace runs in a N2 atmosphere with a small amount of H2 present to protect the heating elements from oxidation. The heat shields are constructed of alumina and the heaters are made from Mo. The substrates are stacked on alumina plates which are continuously pushed through the furnace. The rate of travel depends on the length of the hot zone and, the required time at sintering temperature (about 3-5 hours). Thus the longer the hot zone, the faster the speed through the furnace and the higher the sinter through-put. Since a continuous furnace runs in steady state, there is no time required for the furnace to heat up and cool down. The heat up and cool down cycles are the key rate limitations in a batch furnace.

Conclusion

The five major cost factors for AlN substrates (compared to Al2O3) were discussed: (1) higher cost powder; (2) separate BBO cycle; (3) batch sintering cycle; (4) batch flat fire cycle and (5) non-aqueous processing. By adopting a low temperature sintering configuration, cost factors 4 and 5 are addressed bringing the sintering and flat-firing operations in line with the process for alumina.

Of course, this process will only be appropriate for applications where a thermal conductivity of 130 W/m-K is acceptable. This thermal conductivity should be acceptable for most HBLED, RF and power semiconductor applications. For laser diode telecommunications applications, 130 W/m-K will most likely be too low and conventional higher cost AlN will continue to be utilized.

The availability of a low temperature, continuous sintering process also provides strong motivation for the next phase of cost reduction for AlN, utilization of lower cost, lower performance AlN powder. Again, with a focus on HBLED and power semiconductor applications, sensitivity to impurities such as Fe and Si, which drive up AlN powder costs, may not be anywhere as stringent as applications such as RF and microwave (where dielectric properties at high frequencies are important). The combination of lower cost powder and a continuous sintering process would move AlN substrate pricing much more in line with alumina.

Jonathan Harris, PhD, is president of CMC Laboratories, Inc., Tempe, AZ E mail: jharris@cmclaboratories.com; web: www.cmclaboratories.com

Solid State Technology, Volume 55, Issue 3, April 2012

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HB-LED packaging accounts for 40% to 60% of finished LED cost. This makes packaging the #1 target for cost reduction.

By convention, LED package costs do not include the cost of converting a finished LED to a lighting product ? the "Luminaire". Mark McClear of Cree has repeatedly said an integrated approach is needed to deliver an attractive value for consumers. I'll come back to his point at the end.

A few years ago HB-LED packages were assembled from many discrete parts. These included a metal lead frame, a molded pocket for the LED, a zener diode, a mirror coating for the pocket, a heat sink for the LED, wire bonds for electrical connections, a sprayed on phosphor coating, an encapsulant to protect the assembled parts, and an attached lens.

Today LED packaging is using an integrated thin film approach. A single AlN "panel" about 100 mm square is used. Top side patterns provide a LED heat sink, area for wire bond connections, and electrical traces to vias that connect to the bottom side. Bottom side patterns provide for heat transfer and surface mount connections. Significant savings are realized by doing "panel" scale assembly. For example, lenses are molded 500 at a time on one AlN panel.

Philips-Lumileds has changed their LED structure, to enable flip-chip mounting of the LED on the AlN panel. This eliminates the wire bond cost, and eliminates the area needed for wire bonding. This enables a smaller, lower cost LED package. Expect more flip-chip LED designs.

An analysis of packaged LEDs used for LCD-TV backlighting shows that much of the HB-LED package is a "frame" around the LED. This area does not increase significantly as LED area increases. The real goal is to reduce the cost/lumen, not just the package cost. By increasing lumens emitted from a package, one can reduce the packaging cost per lumen.

This tactic is already being employed in HB-LED packages ? several small LED chips are being mounted inside one package. This provides an added benefit. The LEDs can be wired in series to increase the operating voltage. Higher voltage reduces the power conversion costs in the Luminaire. Which leads back to Mark McClear's point ? consider the Luminare cost.

The Resor Associates' COO model was designed to study the tradeoff between package costs, LED area and LED yield. It is clear that larger LED chips significantly improve the cost/lumen for finished LED's. As yield improves, the optimum tradeoff shifts to larger LEs. So add improved LED yield to the roadmap for LED package cost reduction!

From the life cycle of ICs and FPDs it is clear that LED makers will use some of their cost savings to elaborate the product in ways that reduce the finished Luminaire cost. The most promising idea that I've seen is "integrated" LEDs. For example, one could form two strings of 40 LEDs each. These could operate directly at a line voltage of 120volts, eliminating the power conversion parts in the Luminaire. Why don't we see integrated LED products today? Defects/cm² are too high in LED fabs ? a significant reduction in defect levels is needed first.

Bottom line, there are many ways to reduce the packaging cost in LEDs. But to realize some of these one has to look beyond the traditional LED package to the Luminaire and to the LED chip.

Solid State Technology, Volume 55, Issue 3, April 2012

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