A heat spreader is most often simply a copper plate, having high thermal conductivity. Functionally, it is a primary heat exchanger that moves heat between a heat source and a secondary heat exchanger. The secondary heat exchanger is always larger in cross sectional area, surface area and volume. By definition, the heat is "spread out", such that the secondary heat exchanger has a larger cross sectional area contacting the heat spreader than the heat source. The heat flow is the same in both heat exchangers, but the heat flux density is less in the secondary, so it can be made of a less expensive material such as aluminum, and is a better match to an air heat exchanger, since the low heat transfer coefficient for air convection is adequate for a low heat flux.
A heat spreader is generally used if and only if the heat source tends to have a high heat-flux density, (high heat flow per unit area), and for whatever reason, heat can not be conducted away effectively by the secondary heat exchanger. For instance, this may be because it is air-cooled, giving it a lower heat transfer coefficient than if it were liquid-cooled. A high enough heat exchanger transfer coefficient is often sufficient to avoid the need for a heat spreader.
The use of a heat spreader is an important part of an economically optimal design for transferring heat from high to low heat flux media. Examples include:
- A copper-clad bottom on a stove-top cooking container made of steel or stainless steel
- Air-cooling integrated circuits such as a microprocessor
- Air-cooling a photovoltaic cell in a concentrated photovoltaics system
 |
This physics-related article is a stub. You can help Wikipedia by expanding it. |
 |
This article about an engineering topic is a stub. You can help Wikipedia by expanding it. |
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
