High Thermal Conductivity 3-D Multichip Module Stack Technology

We propose to introduce the use of recently-developed thermal pyrolytic graphite (TPG) material to dramatically reduce the thermal resistance of low-cost, three-dimensional multichip module (MCM) stacking technology. A planar thermal conductivity of greater than 1700 W/m-K makes TPG nearly as conductive as pure diamond, at a small fraction of the cost. By comparison, most common electronic materials used for heat distribution provide thermal conductivities between 100 and 300 W/m-K. When reinforced with an encapsulation for greater strength and stiffness, the composite is usable for structural elements within the 3-D stack. Temperature rise within the 3-D stack may be reduced by factors of 5 or more if certain elements of the 3-D stack structure are replaced with TPG-based components. This type of reduction in temperature will have an enormous benefit on electronic circuit reliability , as well as extend the application of 3-D stack technology to systems required to operate over wide temperature ranges.