Jeffrey G. Stark is president of Sensor Products Inc.

odern microprocessor-controlled electronics and high-power LED lighting operate at elevated temperatures due to Joule heating. As a result, heat sinks, to dissipate temperature, have become important in electronic system designs.

Microprocessor temperatures should be maintained between 60° to 90°C (140° to 194°F), depending upon the specific chipset. This is because applications can microprocessors can malfunction causing freezes or crashes if operating temperatures exceed manufacturer recommendations.

LEDs suffer higher maintenance and shorter lives when their temperatures exceed 125°C (257°F). This is due to the forward voltage dropping when heating occurs; the result is increased current and heating. Thermal runaway can subsequently occur unless the excess temperature is removed. Small copper-plated holes in printed circuit boards are used to transmit heat away from low-power LEDs. However, heat sinks are needed for high-power LEDs. In addition, forced-air convection is used to remove heat from the fins of the heat sink.

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