Thermally conductive plastics (TCPs) –– used to dissipate heat in applications from LED lighting to automotive components –– are a hot item. The global market for such materials is projected to reach $255.6 million by 2025, while growing at a compound annual rate of 13.2 percent from 2020 to 2025, according to a Market Data Forecast report published a year ago.
The global LED lighting sector as a whole is expected to grow at a similar clip. Valuing the sector in 2019 at $54 billion, a market report from last June projected 13.4 percent annual growth for LED lighting from 2020 to 2027. Declining prices for highly efficient light-emitting diodes (LEDs), combined with Increasingly stringent government policies and regulations related to the use of more sustainable lighting technologies, are driving this strong growth.
And, meantime, “smart” public lighting is seen by many as a key growth sector for LEDs and embedded electronics that will only benefit from these types of advanced materials.
The many benefits of TCPs
Generally speaking, versatile, injection moldable TCPs can add design flexibility, while allowing the integration of various functions and enabling part consolidation. And the ability to dissipate heat using lightweight thermoplastics instead of heavier metal or ceramic components also bolster the sustainability argument, especially in weight-sensitive sectors such as automotive and aerospace.
Witcom, a member of the Wittenburg Group in The Netherlands, notes that thermoplastic polymers are good thermal insulators that typically do not dissipate heat easily. But the firm says it has developed a full range of polyamide compounds that offer a thermal conductivity that is 10 to 50 times higher than that of normal thermoplastic polymers. All grades are reinforced, and many contain halogen-free flame retardants.
Witcom says its thermally conductive compounds can be based on such resins as nylon, polypropylene, polybutylene terephthalate (PBT) and even polyphenylene sulfide (PPS) or polyetheretherketone (PEEK).
Dissipating the heat
Avient Corp. is another materials supplier with TCPs in its portfolio. Avient says its Therma-Tech™ thermally conductive formulations are engineered “to combine the heat transfer, dissipation, and cooling capabilities of metals with the design freedom, weight reduction, and cost advantages of thermoplastics.” Formulated using engineering resins along with proprietary conductive additives, these materials have been shown to improve thermal conductivity by 50-100 times that of conventional plastics, according to Avient.
Its TCP compounds find use in a wide range of heat-sensitive applications –– including housings for the advanced driver assistance systems (ADAS) –– where protecting sensitive electronics against hotspot formation is critical. Traditional materials such as aluminum provide excellent thermal conductivity, but there is a tradeoff –– aluminum is heavier, isn’t easily formed into complex shapes, and inhibits part consolidation.
Mono-material, multifunctional
Leverkusen, Germany-based Covestro AG is another to recognize these vital advantages. It adopted a novel, mono-material strategy, combined with multishot molding and in-mold assembly, to develop a multifunctional vehicle headlamp with numerous benefits. In this design concept, Covestro uses various polycarbonate grades, including its Makrolon® TC grades to replace aluminum heat sinks.
While being significantly less expensive to manufacture, this headlamp also reduces the number of components from more than 50 to five, requires 18 fewer process steps than today’s typical headlamp, and can slash the weight of each headlamp by up to nearly 4 pounds.
Now, Covestro is exploring taking its mono-material, heat-dissipating PC resin into another very promising market that incorporates LED technology –– smart public space lighting and security lighting. Traditionally, obstacles such as excessive heat and harsh elements would limit the potential of using thermoplastics in many of these demanding applications.
But Covestro’s latest efforts –– revealed during the recent CES 2021 virtual trade fair –– involve using a single plastic material (polycarbonate) to empower LED functionality in surprising ways, from security cameras to smart lamps.
Lighting up ‘smart’ cities
Others see the potential in advanced street lighting, as well. A recent article by Axios noted how cities are “rushing to replace their legacy streetlights with ‘smart’ LED fixtures that could one day be able to find you a parking space, monitor air quality, and announce an oncoming thunderstorm.”
In fact, streetlights “are becoming the backbone of larger smart city initiatives,” according to a November 2020 report by the Northeast Group LLC, a smart cities market intelligence firm. It predicts that cities –– which can see up to 40 percent of their energy costs consumed by streetlights –– will invest $8.2 billion in these products in the next 10 years. Further, the group projects that more than 90 percent of streetlights will be LED by 2029 and 35 percent will be connected.
By leveraging the cloud and existing infrastructure, a currently “dumb asset” can be upgraded to deliver useful data and functionality. Technology company Intel says it envisions a day when street lights “do everything from traffic and parking control to guiding people out of danger during an emergency (by flashing in the direction of evacuation).”
Joel Matsco, senior marketing manager for electrical, electronics and appliances for Covestro in Pittsburgh, said his firm is actively exploring how best to embed electronics and connectivity into any number of devices, as part of a broader “smart cities” initiative. He foresees the efficient integration of displays, antennas, lighting, 5G connectivity, cameras, microphones and audio into such devices.
From security lights…
So Covestro decided to work with Pittsburgh studio Bally Design on this lighting project. The outdoor security light concept they came up with uses various grades from the company’s resin portfolio, including reinforced PC/ABS for the base, its Makrolon thermally conductive PC for a central component to replace aluminum heat sinks, a reflective white grade that can reflect up to 95 percent of the LED light, and a translucent grade that is infrared-transparent. The concept design includes both a vision camera and an infrared (IR) camera.
A UV-stabilized Makrolon PC grade is used to avoid yellowing of the clear lenses due to sun or LED exposure. The entire unit also needs to have good impact strength and a high degree of weatherability to protect against heat and cold as well as the ingress of water and dust, etc., Matsco said.
This monomaterial, adhesive-free approach also has end-of-life advantages, he notes. The aim is, when the light reaches the end of its useful life, to be able to open it up, remove the electronics, and perhaps a rubber gasket and a couple of screws, and throw the whole thing into the bin to be ground up and recycled.
…to public space lighting
One of the concepts that Bally and Covestro envision involves applying this technology to public space lighting, such as those lights one might find at a bus stop or on a subway or train platform. In addition to serving as a traditional floodlight, the device would feature wi-fi connectivity with either 4G or 5G antennas, and could serve as a hotspot that customers could use for internet access, as well as a motion-sensitive camera. A closed-circuit camera within the body could be used to monitor activity in the immediate vicinity, to provide enhanced security.
The device’s body, which Matsco estimates would be about 18 inches long, can integrate a display, perhaps using colored LEDs, that would offer information on such things as route numbers, schedule updates, trouble alerts, and current time and weather conditions. The T-shaped body of this public space light would be made of Makrolon TC, as the various functions would generate quite a lot of heat that needs to be efficiently dissipated.
Thermally conductive resins help enable this type of design concept. Being able to mold the parts, as opposed to machining and assembling them, totally changes the equation, Matsco says. There is greater design freedom, with maximum functionality and increased recyclability, all at a lower fabrication cost.
That’s an idea worth shining a bright light on.
Standards
Thermal Conductivity – ISO 8302
Thermal Conductivity – ASTM C177
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Great Article Bob. I finished a project last year where we switch an aluminum house to a PPS Thermally Conducted compound. It not only performed better than the aluminum part plus it was significantly lower in cost. Aluminum coated with PFA $150 to $160/part. Injection-molded part $15.00. We also reduced weight which was important
Excellent Article Bob .You have put great content that will help to find valuable information. Thanks for this great article.