The global lighting market is clearly in transition, from traditional lighting technologies to light emitting diodes (LED), according to “Lighting the Way”, a report from McKinsey. This report calculates the LED share in general lighting will be 45% in 2016 and almost 70% in 2020 – an upwards adjustment of their own 2011 findings, by twoand fivepercentage points. Why this is so and which LED developments most recently were brought to the market can be found in this article.
First patent of a Philips filament lamp (right) from 1905 and the structure of a LED lamp on the left (photo: Philips)
According to the McKinsey study the global lighting market is impacted by a number offactors. Three are particularly important: the macroeconomic situation, which is influencing new construction and thus the number of new lighting installations; energy efficiency regulations and energy awareness, which are redefining lighting product portfolios; and government action limiting certain energy sources – key being nuclear power – which is expected to result in a boost for energy-efficient lighting products, such as LEDs.
The global lighting market is expected to have revenues of over €100 billion in 2020, with 5% annual growth from 2011-2016, falling to 3% from 2016-2020. The LED lighting market size overall is anticipated to be around €37 billion in 2016 and €64 billion in 2020. The study’s sector breakdown forecasts a market of around €83 billion in 2020 for general lighting (residential or office lighting), the largest lighting market. Automotive lighting (around 20% of the market) is expected to be worth around €18 billion by 2020. Backlighting is forecast to achieve €1-1.5 billion by 2016, influenced by an accelerated penetration of organic light-emitting diode (OLED) products.
LED is regarded as the most promising technology in terms of commercial viability in 2020. This is in consequence of price erosion due to a considerable overcapacity of LED chips and slowing demand for LEDs in the backlight segment – currently still the largest LED package market segment. Although the price premium on LED lighting products remains high, faster price erosion is pulling payback time forward. Furthermore, the energy efficiency of LEDs exceeds that of other existing lighting technologies, which makes it an attractive alternative to them.
LED for backlit applications
Evonik Cyro’s Acrylite LED Whites is a new line of Acrylite LED acrylic moulding and extrusion compounds specially formulated and designed for backlit LED applications. The acrylic compounds are intended for use with intense LED light sources and is suitable for a wide variety of uses, such as luminous ceilings and walls, decorative lighting, displays and creative lighting profiles, automotive interior accent lighting and signage.
Comparison of three different materials with LED backlighting: Acrylite LED (furthest left) is intended to offer LED hiding power in combination with good light transmission. (photo: Evonik)
Evonik developed Plexiglas POQ66 for televisions, which are becoming ever flatter and more energy-saving. These speciality products are claimed to provide high light transmission combined with a low refractive index, which makes it a good material for manufacturing light guides. They are also suitable for backlit LCD televisions, where LEDs feed light into a light guide plate via the edges, which provides uniform illumination. The plate is the central element of the backlight unit, which means that televisions can be made flatter. At the same time, they save electricity because they use LEDs instead of cold-cathode fluorescent lamps (CCFLs), and need fewer LEDs than direct backlighting modules.
Structure of a backlight unit for LCD displays (photo: Evonik)
The new generation of Thermx polycyclohexylene-dimethylene therephtalates (PCT) from Ticona have also been developed for backlighting applications, as well as for general lighting. The grades are said to deliver the good initial reflectance and stability required in LED packages. Thermx LED 0201 and LED 0201S are fibre filled, super-white PCT compounds. They are intended to achieve the heat and light stability requirements for reflector resins.
The fibre filled PCT compounds are intended for LED display backlight and general lighting applications. (photo Ticona)
DSM‘s high-flow Stanyl ForTii LED LX is a mineral-filled grade, especially introduced for use in LED packages. It is claimed to deliver good reliability over time and, more specifically, high initial reflectivity, as well as mechanical strength. Its high flow properties make it suitable for use in high cavity tools. DSM asserts that Stanyl ForTii LED LX outperforms competitive PPAs because of its specific polymer structure. Good reliability and LED lifetime are achieved through its strong adhesion to silicones and epoxy encapsulates, as well as the metallic lead frame, which avoids chip degradation from moisture or air diffusion through interfacial delamination phenomena.
LED-specific grade of Stanyl ForTii high temperature polyamide with halogen-free flame retardant grades as a material solution for LED packages (photo: DSM)
Thermal management
As demand rises for LEDs with higher intensities and longer life spans, there is a corresponding need for better thermal management; high-power LEDs require efficient heat sinks to sustain performance over longer lives. However, as miniaturisation reduces the size of LED fixtures, the need rises for lighter-weight materials, which offer design flexibility including the ability to form thin-wall parts. Another challenge to conventional heat sink materials such as die-cast aluminium is sustainability, as the manufacture of aluminium heat sinks contributes significantly to upstream waste and energy consumption. Sabic Innovative Plastics says that its thermally-conductive Konduit compounds are able to either replace aluminium completely, or complement it in new designs, particularly for lower-wattage bulbs. A product environmental study conducted by Sabic, in partnership with the sustainability consulting firm GreenOrder, says that LED heat sinks made with Konduit compounds instead of die-cast aluminium can typically avoid 87% of the energy consumed and greenhouse gases emitted during manufacturing and fabrication. The lightweight electrically isolative compounds, which can be injection moulded, also claim to offer greater design freedom than aluminium. The material can also be self-coloured, which eliminates the need for secondary painting.
Bayer MaterialScience’s polycarbonates for LED cooling elements, such as Makrolon TC 8030, also claim to be alternative to aluminium. These allow the cooling ribs to be more delicate and lighter and the injection-moulded cooling elements require no post-treatment, enabling cost-effective production and reduced energy consumption.
PC can also offer greater design freedom than glass and metal in the design of LED components, which are frequently very small and geometrically complex. Furthermore, it is lighter. For these reasons, it is used for injection moulding of items as LED lenses for dipped headlights and tail lights, as well as light guides for daytime running lights. It can be used at temperatures up to 120°C and its high refractive index allows optical components to be very thin, which is particularly beneficial for injection moulding.
Polycarbonates for LED cooling elements, such as Makrolon TC 8030, are said to be an alternative to aluminium. (photo: Bayer MaterialScience)
Guidance by PC lenses
Hella KGaA Hueck, in close collaboration with Bayer MaterialScience, has developed Eco StreetLine, a modular street lighting solution. “The use of LED technology alone can reduce energy consumption by up to 70%, versus conventional streetlights,” explains Oliver Thurau, Sales Manager at lighting and electronics specialists Hella. Depending on ambient lighting conditions, streetlights can be dimmed by as much as 50%. The long service life of the LED modules – approximately 50,000h, or 12 years – also contributes to reduced operating costs. The company has developed special polycarbonate materials, marketed under the name Makrolon LED, for these and other optical applications. It can be injection moulded.
With the modular and innovative street lighting system Eco StreetLine, the energy consumption can be reduced by up to 70% versus conventional streetlights. (photo: Bayer)
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