A heat sink restraint that absorbs shock and facilitates the application
of a calibrated hold-down force to a heat sink. The restraint comprises a
fluid-tight housing and a piston assembly including a piston and a shaft.
The shaft has first and second ends extending from the housing through
seals that allow axial movement of the shaft. The piston is disposed
within the housing for axial movement with the shaft. A dampening fluid
fills the housing about the piston assembly and a dampening orifice or
passageway establishes restricted fluid communication between regions
within the housing above and below the piston. A spring is disposed
within the housing between the piston and the housing to bias the housing
in a retaining direction. A first end of the shaft is selectively coupled
to a circuit board and the second end includes a visual indicator for
indicating the amount of the applied hold-down force.