Hybrid heat sinks can be produced by cold gas spraying. In this case, aluminum heat sinks are coated with copper to increase the heat spreading in the heat sink base through the high thermal conductivity of the copper layer.
The advantage over thermal spraying method is that the coating temperature is clearly under the melting temperature of the aluminum during cold gas spaying. Layer thicknesses of a few hundredths of millimeters up to several millimeters are possible.
The left image shows a cooling profile after the coating with a 2mm copper layer; at the heat sink on the right side, the copper layer is planned by milling – both heat sinks are from Seifert.
In addition to the improved thermal conductivity, the applied copper layers can produce a solderable surface to dissipate components directly on the heat sink.