What Is A Good Heat Sink?

A heat sink is a passive heat exchanger. This means it transfers heat from an object to a coolant, either air or liquid. This coolant then dispels any heat generated by the object.Heat sinks are used in many essential electronic devices, including as central processing units in computers and in power electronics.A good heat sink must be made of the right kind of material to perform its function well. Along with the material of the heat sink itself, another crucial aspect in its operational effectiveness is the thermal interface between it and the component.Mica, with its natural conductive qualities, mica is an ideal material for use as a thermal interface and insulator of heat sinks.

 

Heat Sink Materials

The most common heat sink materials are aluminium and copper alloys.Aluminium alloy provides the starting point for many heat sinks. This is because aluminium alloy has high thermal conductivity, but is also easy to manipulate mechanically because of its softness.Another option is to bond copper and aluminium together, with aluminium remaining the dominant part, because of it lighter weight. This combination has been increasingly used in heat sinks for computers.However, while aluminium surrounded by a copper plate can be effective, the copper and aluminium do not always bond together as tightly as necessary, making this cheaper option a less reliable one.Another growth area is in carbon-derived materials, combined with aluminium. This takes advantage of aluminium’s lighter weight but is more conductive than copper.Natural graphite composite materials are also on the rise in heat sinks. Again, the advantage here is weight.Generally, in terms of performance, traditional aluminium and copper heat sinks perform most consistently.

The Importance of the Thermal Interface
The heat losses from a power electronics device must get across different interfaces between materials. A component will have a casing, for example, so any heat must move from this to the surface of the heat sink. There is also the heat transfer which must occur between the heat sink and its surroundings.Each of these transfers will have its own thermal resistance, and the combination of these will affect the efficiency of the entire system.Therefore, the task of the relationship between device and heat sink, taking these things into account, is to minimise the overall thermal resistance or maximise heat flow.The choice of materials acting as a thermal interface can help greatly in this function.In computer processing units, for example, the thermal interface material will be positioned between the processor and the heat sink.Used with other parts, mica components are an extremely effective thermal interface in heat sinks. These components include mica washers for use with heat conductive paste, and mica wafers for mounting semiconductors to heat sinks.This is because mica is lightweight but strong, and highly adaptable. It is a technically superior insulator, able to withstand both intense electric fields and high temperatures.