Application of conduction-cooled PCBs and composite materials in an aerospace system

Innovative application of carbon composite layers into multilayer printed circuit boards affords CTE matching to semiconductor materials, PCB warpage control, weight reduction, heat transfer, and reduced component operating temperatures for improved performance and enhanced reliability. Manufacturing processes have been developed and matured for thin sheets of CTE-matched composites, attributes and performance have been validated, and these technologies are now being introduced into aerospace electronics system design and manufacturing. Dissipating heat loads from high performance devices mounted on a complex multilayer PCB has presented significant challenges in high reliability electronic systems. These composites replace a heavy copper thermal plane within the PCB for critical high heat flux devices, such as RF modules. Improved CTE matching of an exposed PCB thermal plane to GaN and SiC semiconductor die allows elimination of intermediate package materials to achieve lowered thermal resistances and ultimately lower system life cycle costs, by incorporation of these commercially available developments. Use of similar thermally-conductive composites for submounts and enclosure frames extends the concepts of CTE matching, weight reduction, warpage control, and enhanced reliability and cost control.