scope:

Devices of large size with high power consumption are fairly common. A heat sink may be used to dissipate heat from devices with high power consumption or those outputting a large amount of thermal energy. Such devices may endure high mechanical compressive stress from the heat sink resulting in failure; for example, issue like die crack could lead directly to electrical malfunction.

As Figure 1, heat sink is used for the device of FC-BGA package with lid. Heat sink may be used for other packages, like package with stiffener, sometimes even for lidless or bare die.

Mechanical compressive strength is an inherent property of the device. Mechanical over stress and excessive localized loading may cause device failures. Permanent changes in electrical and/or physical characteristics can be induced by mechanical overstress. It is therefore recommended that device suppliers provide guidance to their customers on the acceptable level of initial mechanical compressive strength that a device can safely withstand.

This test method is intended for customers to determine the ability of a device to withstand the mechanical compressive static stress generated when a heat sink is being initially attached to the device, and to help the customer generate design rules for their heat sink design and validate their thermal solution.

This test method does not assess the long-term effects of static stress. This test method is for the qualification of the customer's heat sink design and assembly process with respect to the amount of static force the device can withstand when the heat sink is initially attached. Permanent changes in electrical and/or physical characteristics can be induced by this mechanical stress.

This method is intended for devices to which compressive static loading is likely to be applied.