At the Strategies in Light show in Santa Clara, CA, USA (1–3 March), Dr Giles Humpston, applications engineer at Cambridge Nanotherm Ltd of Haverhill, Suffolk UK, will outline how Nanotherm's thermal management technology can help LED designers square the circle of performance-to-price in his presentation 'Using Nanoceramic to enhance the performance of LED subsystems at reduced cost' (3 March, 1.45pm).
As LEDs continue to transition into the general lighting market, high-power packaged LEDs are becoming ubiquitous. High-power LEDs are typically >1W in a small (10mm2) footprint, notes Cambridge Nanotherm. At best, only 45% of the electrons put into the device will be converted into visible photons – the other 55% will be converted into heat. This is the problem: How to get the heat out of the packaged LED as quickly, and cost effectively, as possible.
Until now electronics-grade ceramics, in particular cost-effective alumina (Al2O3), have been used as a substrate in high-power LEDs. Where Al2O3 falls down is in its thermal performance – at about 20W/mK it's a poor performer, says the firm. For the more exotic aluminium nitride (AIN) this is 160–200W/mK (depending on purity); good thermal performance but costly. What is needed is a solution that offers good enough thermal performance with a price tag that is more palatable than AIN.
Humpston will be demonstrating how a patented process to convert the surface of standard aluminium into an ultra-thin layer of nanoceramic, finished with a fully inorganic sputtered copper wiring trace, is a suitable material for the high-power packaged LED industry.
Falling right in the thermal sweet-spot of 152W/mK with a price tag sitting between Al2O3 and AIN, nanoceramics open up a new class of material, says the firm, aided by ease of manufacture, filled copper vias and economies of scale.
