Giving automotive lighting system designers a lighter, cooler and less expensive method of mounting visible LEDs, TT electronics IRC Advanced Film Division recently developed an economical anodized aluminum substrate material with superior thermal conductivity that addresses the problem of heat dissipation in direct-mounted LEDs.
Designated as Anotherm substrate, the thermally conductive aluminum alloy material enables design engineers to mount visible LEDs and other components directly to it, thus eliminating the need for attached heatsinks, mounting hardware and the associated assembly costs. Economical solderable thick-film conductors can be screen-printed directly to the Anotherm substrate to connect surface mount packaged components as well as wire-bonded die.
In addition to automotive LED applications, the Anotherm substrates are being designed into automotive power electronics circuits, motor controls and power amplifiers. The Anotherm substrates are made from 3003 or 6061 aluminum alloy, which exhibits a thermal expansion coefficient similar to FR4 PC board (23.4 ppm/K vs. 16-20 ppm/K, respectively); yet, the material’s thermal conductivity (the ability to dissipate heat) is characterized at 173 W/m-K—far superior to other types of traditional substrates (0.8 W/m-K for FR4 PC board; 17.3 W/m-K for 304 stainless steel; or 21 W/m-K for 96% alumina ceramic).
An insulation system consisting of a thin layer of anodized aluminum oxide is chemically grown on the aluminum core, producing a dielectric layer approximately 0.0014-in. thick (0.035 nm), which provides an inorganic insulation that is not affected by temperature or chemical exposure.
This rugged construction gives Anotherm technology the ability to operate in extreme temperatures—up to 400°C (without soldered components); or up to 175°C using high-temperature solder. Maximum operating voltage is 250 Vac, and thermal impedance is characterized at 0.2°C/W. The Anotherm material can be made in any size up to 8 in. x 10 in. (203 mm x 254 mm) and in any thickness up to 0.75 in. (19 mm).
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