A circuit card assembly includes a heat sink, a locking mechanism, a first thermal path, and a second thermal path. The heat sink couples to a circuit board and has an upper surface and a lower surface. The heat sink has a channel extending downward along the upper surface of the heat sink. The locking mechanism is disposed within the channel and includes a plurality of solid wedges movably arranged within the channel. Movement of the wedges is effective to secure the circuit card assembly to a holder. The first thermal path extends from the circuit board through the heat sink to the lower surface of the heat sink and removes thermal energy from the circuit board. The second thermal path is formed from the circuit board, through the heat sink, and then through the wedges to the holder. The second thermal path removes thermal energy from the circuit board that is greater than a leakage amount.