Consequences of Using a Copper Heat Sink Base

Upgrading a heat sink base to copper is one way to reduce the overall thermal resistance. But, despite the boost in thermal performance from using a material with twice the thermal conductivity of aluminum, copper has a couple of notable drawbacks: weight and cost. Copper is over 3-times denser than aluminum and over 10-times more expensive than aluminum.

The chart below illustrates the performance, weight, and raw material cost implications of changing the heat sink base from aluminum to copper. Depending on application requirements, the ‘copper penalty’ might not be as high as the figures above might suggest.

If the base temperature rise is required to be under 23 oC, either a 4.5mm aluminum or 2.0mm copper base (in green) would meet that requirement. Here the penalty of changing to copper is 63g and $1.64 in raw material, with no performance gain. Heat sink height constraints may limit the base thickness to below 4.5mm. In this case, a change to copper might be warranted.

Further, if base temperature rise is required to be around 10 oC, then copper is likely the only solid metal option. At this point, a vapor chamber base or aluminum base with heat pipes also become options. These 2-phase solutions would achieve delta-Ts in the single digits with weight just above the aluminum alternatives.