Methods for establishing thermal joints between heat spreaders or lids and heat sources

A method of establishing a thermal joint for conducting heat between a heat spreader and a heat source of an electronic device, the heat source having a normal operating temperature range, the method comprising:

• positioning a thermal interface material (TIM1) in an initial solid state in the form of a pad between the heat spreader and the heat source, wherein the thermal interface material comprises a phase change thermal interface material;
• and
• heating the thermal interface material, while under pressure, to a temperature within a range from about 45 degrees Celsius to about 70 degrees Celsius such that the thermal interface material becomes flowable to form a thin bond line between the heat spreader and the heat source and establishes the thermal joint between the heat spreader and the heat source, whereupon removal of the pressure, the thermal interface material returns to the solid state and remains solidified as the thermal interface material precludes the heat source from heating beyond the normal operating temperature range during operation of the electronic device and heat is flowable through the thermal joint from the heat source to the heat spreader during operation of the electronic device whereby temperature of the heat source is reduced;
• wherein the thermal interface material is silicone free;
• and
• wherein the phase change thermal interface material is shear thinning and thixotropic such that the phase change thermal interface material is not flowable at the temperature within the range from about 45 degrees Celsius to about 70 degrees Celsius except under pressure and such that the phase change thermal interface material maintains shape unless force is applied even when the phase change thermal interface material is at the temperature within the range from about 45 degrees Celsius to about 70 degrees Celsius.