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Converting Thermally Conductive Materials to Meet LED Performance Challenges
LEDs (Light Emitting Diodes) are the latest development in the lighting industry. Made popular by their efficiency, range of color, and long lifespan, LED lights are ideal for numerous applications, including night lighting, art lighting, and outdoor lighting. These lights are also commonly used in electronics and automotive industries, signage, and many other uses.
By providing efficient energy conversion and extended lifespans, these bulbs help to save money on replacement bulbs and electrical energy consumption. LED light bulbs are designed to convert electrical energy into light through a microchip that illuminates the tiny light sources that produce visible light. This process uses up to 90% less power than traditional incandescent and fluorescent bulbs.
LED lights are directional light sources. This means the bulbs emit light in specific directions instead of incandescent and fluorescent lights, which emit light in all directions. The specified directional lighting and microchip electrical conversion help enhance efficiency and light quality.
LEDs provide a wide range of benefits for design engineers:
- High energy efficiency: LED lights are more efficient than standard fluorescent and incandescent lights. LED light bulbs consume less energy and are more efficient in converting that energy into light than traditional fluorescent and incandescent light bulbs are.
- Produce a long service life: LED light bulbs are designed to last up to 6 times longer than other types of lighting. This helps to save money and waste on replacement bulbs. LED lights are also not worn down by quick and repetitive shutting on and off as other types of light bulbs can be.
- Cold temperature operation: While other lights require higher voltages to operate in cold temperatures, LED lights remain operational and reliable in colder locations. This makes them ideal for lighting refrigerators and storage spaces.
- Available in a wide range of colors: LED lights come in a range of warmer or cooler lighting, providing the ideal shade of light for any environment.
- Controllability: LED lights are semiconductor devices that can be dimmed with controllers. LED lights offer continuous dimming capabilities, while other types of lighting can only provide step-level dimming.
- Instant On: Some other types of bulbs take a moment to reach their full brightness. On the other hand, LED lights snap onto their full power when the switch is flipped.
- Rugged and durable: By foregoing glass encasements, LED lights boast added durability and resistance to breakage. LED lights are typically mounted on circuit boards and connected with soldered leads. This increases LED lights' resistance to vibration and other types of disturbances.
- No UV emissions/very little infrared: LED lighting helps protect carpets, artwork, window coverings, and painted surfaces from any potential infrared or UV emission damage.
- Small size allows for design flexibility: LED lights come in a wide range of sizes allowing for greater design freedom.
All the advantages of LEDs come with one concern – they heat up. High-brightness diodes, especially in LED clusters, can cause sufficient thermal challenges to impact LED performance.
LED diodes consist of a die semiconductor material impregnated or doped, with impurities to form a p-n junction. Light is projected upward in the LED and heat downward into the base. As heat rises within an LED, light output diminishes. Proper thermal management in designing modules for LEDs, whether on a circuit board or within an enclosure, requires assessing materials and methods for dissipating heat. EIS can recommend appropriate materials and designs to provide the required thermal conductivity and electrical insulation.
Thermal Interference Materials (TIMs) are vital components in all LED lights. TIMs help preserve LED lights and function at maximum capacity by managing the heat produced by the lights. EIS combines and tailors these materials to fit customized and specific needs in any LED application.
TIMs sit between the LED and the heatsink. There they provide high thermal conductivity to efficiently transfer heat emitted from the light source to the heatsink. This is accomplished by displacing the air within the LED. Without TIMs, heat is not transmitted efficiently and LED performance suffers.
Suggested materials and adhesives could include:
- Conductive adhesives and greases: including phase change materials, adhesives and greases that sit between heat generators and heat sink, pressure-sensitive tapes that mount to heat sinks, thermal fabrics and tapes providing thermal conductivity, and silicone sponge materials for heat absorption. Conductive adhesives and greases are from top suppliers such as 3M, DuPont, Von Roll, and Saint-Gobain.
- Tapes: adhesive tapes are available for various applications, including bonding, joining, marking, and covering for use in industries and fields such as electrical, automotive, manufacturing, and much more. These tapes eliminate the need for mechanical fasteners, saving both material and process costs. Many tapes are offered, including electrical tape, vibration dampening tape, die-cut foam tape, transfer tape, and more.
- Ceramic and metal-filled elastomer gap-fillers: gap fillers help to create pathways for efficient heat transfer in between heat-generating mechanisms, heat sinks, heat spreaders, and other cooling devices. Interface Pad 3M 5595 provides excellent thermal conductivity.
- Coated fabrics: specialty converted coated fabric materials are available in a wide variety of options at Fabrico. Laminated, slit, or die-cut coated fabric products are offered for insulation, surface protection, chemical resistance, and thermal management applications. Fabrics can be laminated with pressure-sensitive adhesives, conductive adhesives and can be die-cut to accommodate EMI/RFI shielding and structural requirements. Specialty converted coated fabric materials are available from top suppliers DuPont, Isovolta, Saint-Gobain, and Von Roll.
- Phase-change materials: phase change materials (PCM) melt and solidify at certain temperatures while storing and releasing large amounts of energy. PCM such as 3M 8926-02 and Nitto-Denko TR-5925.
There are a variety of converted materials needed beyond thermal management materials that are critical in the performance, reliability, and safety of LED lighting. Materials used for electrical and fire safety are crucial in LED function by eliminating electrical and fire hazard risks caused by the released heat.
Once the best materials are selected, EIS provides the finished die-cut thermal management component as well.
Integrated direct connected LED luminaire designs are ideal for maximizing cost-effective light efficiency. Flame barrier products (FRB) are used in addition to heatsinks and thermal interface materials at the light fixture housing-enclosure level. FRBs are thin insulation apparatuses made of inorganic materials. These FRB insulation materials provide incredibly high flame and heat resistance in applications such as:
- General-purpose lighting luminaires (including LED)
- Electric and electric hybrid vehicles
- Electrical devices
With excellent heat and flame resistance, FRBs offer arc and track resistance, dielectric strength, flexibility, and convertibility.
EIS also provides EMI/RFI Shielding solutions to lower magnetic interference or radio frequency interference. Although LEDs operate with a direct current, lighting controls and dimming circuits with trebling high frequencies. EMI/RFI management can take several different forms, such as:
- Electrically conductive adhesive transfer tape
- Electrically conductive gaskets (ECG)
- Electrically conductive cushion pad eCAP
- EMI/RFI shielding tape
- Foil and conductive fabric backings
- Electrically conductive & non-conductive adhesives
- EMI/RFI absorbers
- Various magnetic permeability and thicknesses
Making the right choice of electrical insulation, EMI/RFI shielding, and flame-resistant barrier protection is essential for proper thermal management and material selection to make your LED lights as functional and efficient as possible.