Solid State Lighting the Way
By Bob Hult, Bishop & Associates Inc.

There are very few 100-year-old technologies essentially in their original configuration that are still in mainstream use today. I suppose the internal combustion engine and electric motors fit into that category, but even they have experienced vast improvements in materials and design. Photography and sound reproduction devices are examples of technologies that have been completely updated by the digital revolution. The Edison light bulb has remained our primary source of illumination since the late 1800s, but a variety of factors are converging to ultimately retire the incandescent lamp.

Glass light bulbs suffer from a number of deficiencies, including fragility, relatively large size, and the fact that they begin to burn out the moment they are energized. More recently, global concern about energy conservation and climate change have led to the realization that the standard light bulb is a major source of wasted energy. The compact fluorescent lamp (CFL) is promoted as one solution, with its greatly increased service life, reduced heat output, and low energy consumption. CFLs in a variety of configurations are marketed as a “green” alternative to incandescent bulbs, but like most everything in life, suffer their own set of problems, including: 

1. Higher initial cost

2. Delayed start, slow to full brightness

3. Limited light output

4. Difficult to dim

Early compact fluorescent bulbs were criticized for generating a very harsh white light, and in some cases, created RF interference. Poor quality bulbs have been identified as the source of fires, but these issues have largely been resolved. Dimmable CFLs are now available, but are more costly.

The bigger issue remains, that, in spite of their environment- friendly marketing, CFLs contain a small amount of mercury, meaning that the burden of proper disposal falls upon the consumer. Concerns have been raised about soil contamination and health hazards if all standard light bulbs were to be replaced with CFLs.

Now, lighting fixtures using light emitting diodes (LEDs) appear to be the new winner in the race to replace the common light bulb. Huge strides in the development of high-output white LEDs have allowed them to evolve from simple indicator lights to a leading contender in general lighting applications. LED lamps offer excellent efficiency in a durable package, and contain no hazardous materials. Rather than wasting 90% of the energy consumed by a light bulb in radiated heat, LEDs produce much more useable light per watt.

Manufacturers of LED-based lamps are anxious to avoid the mistakes and lengthy adoption curve experienced by CFLs. Although early LED products generated a very harsh light, new LEDs offer a variety of color tones approaching that of an incandescent lamp. Dimming an LED has been an ongoing issue. Some solutions required expensive controls and low-voltage wiring, but the latest generation of dimmers are compatible with LED lamps and conventional wiring. Prices are still high when compared to standard light bulbs, but they are dropping fast. Applications in street and architectural lighting can be economically justified now, due to the much lower cost of maintenance enabled by the exceptionally long life of the LED. LED illumination is particularly effective for applications that require operation in low temperatures.

LED-based bulbs in conventional lamp envelopes using standard Edison sockets are expected to become a huge market, as consumers replace incandescent bulbs with new LED bulbs.

Governments around the world are creating energy efficiency mandates that are making incandescent bulbs obsolete. A ban on all conventional light bulbs has already been enacted in Australia, to be followed by Canada in 2012.

The U.S. Congress passed the Energy Independence and Security Act of 2007, a bill that will effectively ban the 100-watt bulb in 2012, and eliminate all standard light bulbs by 2014. In January 2011, California became the first state to ban the sale of 100-watt incandescent bulbs, and requires lamps with equivalent light output to consume no more than 72 watts. Even some consumer retailers have gotten into the act; IKEA has stopped selling incandescent bulbs in their U.S. mega-stores.


Because they consume so little energy, LED-based lighting is being considered as a light source in third world countries, where access to electricity is limited. Solar panels that produce DC power for LEDs may be the ideal solution to provie light in remote communities.

Individual LED bulbs with integrated solar cells have already been developed and sold in 33 countries.



Conventional lamps of all types, including PAR reflectors, and fluorescent tubes, are being adapted with LED versions. Most of these lamps are outfitted with multiple LEDs to provide high lumen output in a uniform pattern.


Retrofitting legacy lamp form factors using LED sources is an attractive and immediate business opportunity, but the result tends to compromise some of the advantages that LED sources offer. Incandescent and fluorescent lamps are designed to radiate light in all directions. Reflector bulbs and reflective fixtures are used to direct the light. LEDs, by nature, are directional. Designing a unidirectional bulb using LEDs sacrifices some of the efficiency and complicates the manufacturing process. Standard Edison sockets have no provision for transferring heat from a LED bulb, thus requiring external space-consuming and expensive heat sinks. Since LEDs require low-voltage DC current to operate, conversion circuitry must be integrated into each lamp to allow them to operate on standard 110VAC. Since an LED is an entirely different animal, the advantages of converting to this new source of light are best achieved by recognizing the specific characteristics, both positive and negative, of LED sources, and designing sockets and fixtures that are complementary.

Several leading connector manufacturers have sensed a huge growth market opportunity in this new solid state lighting (SSL) industry and have created separate business groups to address them. LED equivalents in familiar envelopes will grow, but the unique characteristics of LED sources allow entirely new packaging options that will generate demand for pluggable module assemblies, as well as new interconnect systems.

Converting the entire world to SSL sources will be a long-term challenge, given the high cost of individual LED bulbs currently on the market. More immediate volume opportunities exist among manufacturers of overhead lighting fixtures, recessed cans, pendants, as well as table lamps. Many of these companies have been designing fixtures using incandescent bulbs for many years, and have no experience with addressing the technical issues associated with LED sources. Designers of new fixtures are focusing their development efforts on utilizing SSL sources, but are being challenged by electrical conversion, light distribution, and thermal problems.

Connector manufacturers have chosen several different ways to address this emerging market. In some cases, manufacturers have chosen to identify connectors within their existing portfolio, as well as some customized products that can be used with solid-state lighting systems. Amphenol, for example, has produced several brochures that feature connectors that draw on their expertise in rugged and waterproof connections, especially in signage and outdoor lighting applications. FCI Electronics has published a SSL product datasheet that focuses on traffic signaling and outdoor signage, as well as power and control circuits.






AVX has concentrated their SSL product mix on a series of new board-to-board and IDC wire-to-board connector systems, designed specifically to satisfy the requirements of LED applications.









Other manufacturers have begun to focus their efforts on a broader spectrum of SSL components, creating a central source for SSL solutions.

Molex has developed a series of custom LED array holders, including the MP-L, which is designed to simplify the installation of the Cree Xlamp array, and is available in series or parallel wiring configurations. The holder features the simple integration of a heat sink, and speeds installation in lamp and small-fixture applications. Molex now offers four styles of off-the-shelf LED array holders, and several more are in development.



Molex has also partnered with Bridgelux, a manufacturer of LED arrays, to offer the unique Helieon™ LED socketing system. The resulting modules and sockets make the process of changing an LED device as simple as changing a standard light bulb. The initial Helieon modules were designed for low-voltage DC supply, but the next-generation Helieon modules, soon to be released, will include additional features.

Molex also offers a full portfolio of supporting board-to-board and wire-to-board connector systems used in SSL applications.









TE Connectivity has been active in the SSL interconnect market for several years, and has recently taken a more aggressive and holistic approach to the SSL market.

They continue to expand their SSL product mix with individual LED sockets and related interconnect systems.








With the recent announcement of the NEVALO system, TE has made a major commitment to offering a system-level approach to SSL applications. They now offer a complete menu of all SSL components required for a SSL system.










The objective is to provide a one-stop solution that includes a wide variety of LED modules, related interconnects, matching heat sinks, drivers, circuit protection devices, controls for dimming, as well as light pipes.









Designers can select from rectangular and circular LED light modules with a variety of beam angles, color temperatures, and light output.

Unique thermal measurement points located on the modules allow engineers to monitor thermal performance during operation. A thermal test instrument and software package allows designers to verify the thermal performance of a luminaire.

The market for general lighting is undergoing a major change in what has been a sleepy segment of the industry. The shift from electrical to electronic light sources will transform what has been a commodity market dominated by a few major suppliers, to a wide-open field where innovation and technology will bring new vigor and profits to this changing market.

Significant obstacles, including the lack of industry standards, as well as high unit prices, color, and output deterioration over time, have resulted in the current highly fragmented market. The industry is early in the learning curve of what solid state lighting can offer and what will be the most cost-effective solution, but the combination of demand for energy efficiency, together with governmental mandates, portends incredible growth over the coming years.

Bishop & Associates Comments: 

1. Compact fluorescent lamps are becoming the intermediate-term alternative to incandescent lamps, but LED sources are expected to be the long-term solution.

2. Arrays of LED sources mounted on a removable substrate provide greater lumen output and ease of assembly.

3. General adoption of SSL devices for general lighting applications is being tempered by a lack of quality standards, high unit costs, thermal management challanges, and lack of familiarity with this new technology.

4. Dimmable LEDs have now entered the market, along with associated control devices.

5. Consumer demand for environmentally friendly products, governmental mandates for higher energy efficiency, and declining prices are expected to generate huge market growth for SSL lighting products over the next five years.

6. A select group of electronic connector manufacturers are looking for ways to participate in the estimated $100 billion global lighting industry.

7. Solid state light sources packaged in conventional incandescent and fluorescent envelopes will allow consumers to quickly adopt higher efficiency bulbs, but will demand a price premium.

8. LED sources offer entirely new form factors that are smaller and more rugged. Fixtures that take advantage of these features will dramatically alter how general lighting is achieved in coming years.

9. Conversion from electrical to electronic lighting sources will open new product opportunities for electronic connector companies that have traditionally had little involvement in this market segment.

Robert Hult Director of Product Technology, Bishop & Associates Inc. Robert Hult has been in the connector industry for more than 36 years. Hult began his career as a sales engineer for Amphenol. He joined AMP in 1972 and served in several management positions through 1996. In 1997, Hult joined Foxconn as group marketing manager for Intel in Chandler, Arizona, U.S. Prior to joining Bishop & Associates, Hult was the regional application engineering manager for Tyco Electronics. Hult graduated in 1968 from Bradley University with a bachelor of science degree in electronics technology and a minor in business.