Heat Sink Thermal Resistance Model

Again because of the high thermal resistance of plastic a heat sink will be more effective when connected to an exposed metal pad either directly or through thermal vias.

Heat sink thermal resistance model.

In the cases where forced air circulation is used the speed of circulation in m s is a key factor as it enables us to evaluate the obtained thermal resistance. Specific thermal resistance or thermal resistivity r. Laminar turbulent developed and developing flow and heat transfer were considered in the analysis. Thermal resistance is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow thermal resistance is the reciprocal of thermal conductance.

Thermal resistances finite element models were used to predict thermal resistance of packaged devices the values of which closely match the thermal resistance values provided in the stratix ii device handbook table 2 shows the thermal resistance equations for a device with and without a heat sink. The heat sink base thermal resistance can be written as follows if the source is a uniformly applied the heat sink base. A thermal resistance model was set up to analyse the flow and heat transfer in microchannel heat sinks. A heat sink can be added to either the top of the package or directly beneath the exposed pad on the backside of the pcb.

The heat sink thermal resistance model consists of two resistances namely the resistance in the heat sink base and the resistance in the fins. 4 the resistances in a heat sink model the goal of the analysis is to determine the heat sink geometry and a device setup which allow enough heat dissipation for a given devices and working conditions. For example a characteristic of a heat sink. Junction case and case ambient or case heatsink thermal resistances r jc r ca a row vector r jc r ca of two thermal resistance values represented by the two conductive heat transfer blocks the first value r jc is the thermal resistance between the junction and the case the second value r ca is the thermal resistance between port h and the device case.

Thermal resistance tables for a given heat sink according to the type of air circulation natural or forced. If it is not then the base resistance is primarily spreading resistance. To do this it is necessary to know the maximum allowable module case temperature t case the module power dissipation p mod and the thermal resistance at the module to heat sink interface r int. Heat sink thermal resistance delta t for each component part of the heat sink.

Optimum thermal design of the heat sink was then studied using this model and a self developed software package where the influences of the heat sink s channel aspect ratio fin width to. The highest thermal resistance of an assembly is fixed.