New material technologies are helping the growth of the lighting industry
Lighting technology is rapidly evolving with design and energy saving features being the fundamental drivers of the industry.
Many people will not know that the electroluminescence effect was first discovered at the beginning of the last century, but the manufacturing and material technologies were not there to exploit the discovery. It took another 50 years before all the technology came together to launch the first LED. Initially it was just used as indicator lights for electronics, but since then LEDs have evolved into a major lighting technology that may change the future of general illumination.
Huntsman saw the broad range of marketing opportunities for LEDs and began its commercial involvement in the market with support for Siemens in the early 90’s with organic encapsulation solutions for their LED range. Since then it has always been actively involved in the lighting market.
It has expanded its lighting product range to include a white solder mask system which was developed additionally to their green and blue systems to ensure a better reflectivity of LED light assembled on printed circuit boards. Quite recently it has launched a thermal conductive dielectric material to improve the removal of heat removed created by LED light on a printed circuit board.
Today Huntsman materials are used by leading OEMs in every industry sector across the world with the always the highest adherence to specific industry standards.
Dietmar Leibrock, Regional Sales Manager (Germany) at Huntsman Advanced Materials, looks at the important role that new materials play in the future of the lighting industry.
LED encapsulations
Since the first introduction of LED’s in the late 60’s, tremendous improvements have been achieved, both in efficiency, colours and in lifetime. The early models came in pale yellow-amber colour with light output efficiencies of < 0.1 Lumen/watt, then later green and red LED’s were introduced and in the mid 90’s the first blue LED’s arrived, paving the way for white lighting.
Today efficiencies are up to 150 Lumen/watt and the lifetime is currently 30000 – 100000 hours, thus enabling LED to become the next generation of lighting. But all this progress had to deal with one critical limitation – the encapsulation and how to protect the LED from the environment.
Encapsulation materials based on proven Epoxy chemistry have been developed which could withstand the harsh conditions that often surround these LED’s. They must have UV and heat stability (LED’s chip temperatures can rise to140°C) and it is essential that there is 100% transparency with no yellowing of the encapsulation materials. Furthermore, good adhesion to a range of different substrates is a must, together with low curing stress and low ionic content of raw material features.
Huntsman has been working in this area since the early 90’s. Its materials are based on proven pure epoxy chemistry, covering encapsulation requirements for simple SMD type LED’s in all colours up to lamp type blue and white power LED’s. The materials are also available in different viscosities to fit perfectly to various encapsulation processes.
With ISO approved production sites Huntsman can provide guaranteed quality, and consequently has customers for over 15 years such as one global leading lighting OEM as toll manufacturer for their own proprietary encapsulation materials.
Huntsman also provides fully transparent polyurethane systems which can be used in a variety of LED applications. The excellent mechanical properties of the polyurethane systems, their transparency and their non-yellowing characteristics make them ideally suitable for outdoor applications. Their flexibility at low temperatures is also key to withstanding a wide range of temperature changes.
Arathane XB 5601-1 / XB 5600 is one example of transparent encapsulates with excellent UV stability.
White solder masks
The requirements for a highly reflective white photosensitive solder mask are not only its appearance which helps to ensure that there are no short cuts in power, but also how it behaves when applied. Chemical resistance against immersion in tin and nickel gold chemicals and low discoloration after multiple soldering processes are essential.
In addition high resolution capability, good protective power with thin resistant layers and long term thermal resistance (2000h at 120°C) are standard for high reliability applications. Huntsman’s Probimer® range of high performance solder masks fulfils all these criteria.
The features of the Probimer® range are particularly important in sectors such as automotive where the protection of the electrical circuits in all weather and temperature conditions are as critical as the protection of the electronic appliances from the heat of the car engines.
LD flex dielectrics and adhesives
New developments expand the existing Probelec LD Flex portfolio to ensure higher thermal conductivity and solvent free systems. Higher layer thickness can be achieved using only a single application process for flexible and rigid solutions.
Based on 100% flexible epoxy technology, Probelec LD flex products are used as dielectric insulation adhesives for lightning substrates. Applications vary for bonding substrates of various kinds like copper, aluminium, polyimide, polyamide, FR-4 and others. Standard products have a thermal conductivity of around 0.4 W/ mK but new developments will be of improved thermal conductivity.
All products are two component liquid epoxy formulations and thus have extremely good substrate wetting properties compared to film or foil based materials.
Main advantages are:
- Cost Effective Dielectric Adhesive System
- Full Epoxy System
- Two Component System with long shelf life
Probelec LD Flex products are applied with standard well established application and process technologies. Normally the products are applied with standard screen printing or roller coating technology in thickness between 15-100 μm. After low temperature drying they form a tack free surface with good planarisation properties which can then be handled and laminated to the second substrate.
Sales enquiries should be directed by e-mail to: Holders Technology (UK) Ltd
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