Thermal pad
A thermal pad or heat trap is the name given to those soldering surfaces of electronic components on printed circuit boards that are not connected over the entire surface but only with thin webs to larger copper surfaces .
The reduction in the cross-section prevents the heat over the copper surface electrically connected to the soldering surfaces, e.g. B. a mass layer, drains and the soldering process is affected. If the circuit board is heated over a large area, for example with machine soldering such as reflow soldering, where the entire circuit board is uniformly heated, no thermal pads are necessary, but usually do not interfere. In the case of small components (design smaller than 1206), heat traps can prevent the components from erecting during the solidification phase (tombstoning) if one component connection is on a small soldering area and the other is in a large soldering area.
In the case of increased requirements for low heat transfer resistance in the area of power electronics , where, among other things, heat loss is dissipated via the soldering points into the metallic surfaces, thermal pads are a hindrance. Heat traps also have a disruptive effect on thermally optimized printed circuit boards with an aluminum core , such as those used as carriers in LED headlights .
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