US Patent 7278470 Heat dissipation device

A heat dissipation device for an electronic unit includes a heat sink (10), a pair of first heat pipes (20) and a pair of second heat pipes (30). The heat sink includes a base (12) for contacting with the electronic unit (42), a plate (14) spaced from the base, and a plurality of fins (16) arranged between the base and the plate. The first heat pipes are attached to the heat sink and include evaporating portions (22) sandwiched between the base and a bottom portion (162) of the fins for absorbing heat from the base, and condensing portions (24) thermally sandwiched between a top portion (164) of the fins and the plate. The second heat pipes are attached to the heat sink and sandwiched between the base and the bottom portion of the fins.