Heatsinks and Why We Need Them

Heat dissipation is an unavoidable by-product of electronic devices and circuits. To ensure that the component does not overheat, an efficient heat transfer path must be found from the device to the environment. This thermal pathway reduces the temperature rise in the junction of the electronic device. Generally speaking, the devices that run cooler will last longer and perform better.

Heat sinks are used to move heat away from a device in order to maintain a lower device temperature. A heat sink allows a component to dissipate its heat over a larger surface area and transfer that heat to the surroundings — usually air or a liquid coolant. (If the media is liquid, this type of heat sink is frequently called a cold plate.)

Without a heat sink, the silicon junction inside the package could rise far beyond the recommended operating conditions. Heat sinks are used with high-power semiconductor devices such as MosFETs, power resistors, Diodes, IGBTs, etc. They are also essential in optoelectronics such as light emitting diodes (LEDs), where the heat dissipation ability of the component itself is insufficient to moderate its temperature. When used with LEDs, heat sinks absorb and disperse excess heat away from the LED diode, thus increasing light output and extending the LED’s lifetime.

A heat sink is designed to maximize its surface area in contact with the cooling media surrounding it. In passive cooling applications conduction, natural convection and radiation is used to cool a component. Active cooling requires the use of a fan or blower to move air through the heat sink to cooling the component. Air velocity, choice of heat sink material, design, and surface treatment are factors that affect the performance of a heat sink. Heat sink attachment methods and thermal interface materials (TIMs) also affect the die junction temperature of the integrated circuit.

From surface mount devices to multiple unit extrusions, Ohmite offers an array of low cost, configurable, scalable and
compact heat sinks to meet the needs of not only power resistors, but of all active devices.
Designed to secure TO-126, TO-218, TO-220, TO-247, and TO264 packages, plus provide thermal solutions for TO-252, TO263, and TO-268 SMD and BGA devices, Ohmite offers heat sinks appropriate for applications dissipating different wattages and mounting options. Ohmite also offers the ceramic heat sinks for the high-voltage-circuit and chip-on-heat-sink applications. For applications that require more customization, the company has a broad extrusion profile library to develop custom and semi-custom solutions.

This article is just a snippet from Ohmite’s White Paper. Please click here to view the complete document.