The most widely used and successful dielectric materials for printed circuit boards (PCB) are FR-4 and are primarily epoxy based. The epoxies have good combination of dielectric, mechanical, and thermal properties which are very important for printed circuits. However, the epoxy dielectrics are petroleum based and non-sustainable. Furthermore, the petroleum based materials are not cost effective, which becomes obvious in the recent years.

We presented a new soybean oil based resin to replace the petroleum based epoxies for PCBs, which can avoid sustainability issues. Unsaturated soybean oil has been functionalized with different reactive groups and used in different applications. Unfortunately, the thermal and mechanical properties such as glass transition temperature, modulus, etc. are not good enough for PCBs.

Improving the properties of soybean oil resin in a framework of sustainability and cost effectiveness is desirable. In this work, we proposed different chemical routines to modify and functionalize the soybean oil resins for dielectric applications. Multifunctional agent was used to increase the crosslink density of the final polymer. Maximum utilization of functional groups on the molecules was achieved. The rigidity of the soybean oil was increased to improve the mechanical properties. The resin system was also designed to minimize its dielectric constants in order to increase the operation speed of the printed circuits.

Finally, natural fibers such as chicken feather fibers were incorporated as reinforcement to produce biobased composites for dielectric devices such as PCBs.

This project was supported by the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service, grant number 2005-35504-16137.