Imagineering, Inc. | https://www.pcbnet.com/blog/selecting-pcb-materials-for-fabrication/
. Both flame and water resistant, FR-4 has high tensile strength and has good strength to weight ratios. These can be further bolstered by mixing the base epoxy with additives to improve its thermal performance
Imagineering, Inc. | https://www.pcbnet.com/blog/understanding-the-pcb-fabrication-process-from-design-to-delivery/
. These substrates are also preferred for flexible PCBs, as FR4 substrates are pretty rigid. PCB Manufacturing The primary parts of a PCB include the substrate, copper layer, solder mask, and silkscreen
Heller Industries Inc. | https://hellerindustries.com/wp-content/uploads/2022/06/Optimizing-Reflowed-Solder-TIM-sTIMs-Processes-for-Emerging-Heterogeneous.pdf
. However, the high tensile strength of AuSn20, not to mention its cost, limits its use to smaller die only. The high conductivity of metal is due to the majority contribution of electronic phonons rather than lattice vibrations
