What to consider when choosing a heat sink?

A heat sink is a heat exchanger which works passively in order to transfer the heat generated by a device to a more fluid medium, such as air or liquid, to increase the performance of an electronic device. The most commonly known devices that use a heat sink are computers and semi-conductors. The heat sink is a device or substance that is used to absorb any excessive heat that a machine is producing.

The reason a heat sink is so crucial in the design of modern devices is because they require controlled temperatures and environments to be able to work at a peak performance level. When a device overheats, the performance can diminish rapidly and in the more severe cases, can induce power failure and become a safety hazard. The heat sink works to diminish the chance of this happening by dispersing the heat into the surrounding atmosphere through either the air or by means of a liquid coolant depending on the needs and complexity of the machine.

For more on sample heaters see here.

What factors should be considered?

There are many important factors that need to be considered when determining the best heat sink system. One of the biggest factors is the heat flow which is determined by the thermal resistance, thermal conductivity, the cooling method and an efficient surface area. The best optimisation is not just about increasing performance but to help with the cost, mass, size and complexity of a device. In order to make the most efficient heat sink, the manufacturer needs to combine the thermal management system with a practical and cost effective design. The best results come from optimising machining and the finishing of the surfaces, using the best materials for each device.

There are various different cooling options available for the production of a heat sink, these include: Natural Convection, Forced Air Convection and Liquid Cooling. The base level heat sinks use aluminium extrusions to produce a natural air cooling method through an arrangement of fins.

There are more advanced systems which include welded structures, and machined interior designs, assembled by brazing two halves in a controlled atmosphere. Liquid cooling pates are another option for a heat sink. These are designed as either simple drilled plates or systems of inlaid copper tubing, configured for cooling specific areas of a machine where heat is most concentrated.

What exactly makes a good heat sink?

With all these different components, what exactly makes a good heat sink? Most heat sinks start life with an aluminium alloy for a higher thermal conductivity. After this, it is essential to look at and under the machine in question. The areas that need to be considered are:

  • The operating temperature of the machine
  • Heat dissipation characteristics
  • Maximum operational limits for the key components

This helps to calculate the overall thermal flow for the system. The system also needs to be optimised in terms of space, location, accessibility and cost targets.

For more complex systems, it is possible to use simulations in order to determine the heat flow of a machine and the exact way in which the system will work. Simulations are also a good way to see how an alternative or competing technology would work with the machine and whether it increases or decreases the overall performance of the system. The finish of the surface area is just as important as dissipating heat and reducing thermal resistance.

In the latest high power applications such as rail traction and electric vehicle designs, a higher efficiency heat sink is needed. This is where a forced air complex fin solutions are ideally suited for the very high heat dissipation requirements.

This is where Power Products International’s long experience and in-depth knowledge of the various alternative solutions makes them an ideal choice of partner for your thermal management needs.

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