Low Dielectric Constant Material from Hollow Fibers and Plant Oil

Abstract

A new low dielectric constant (k) material suited to electronic materials applications was developed using hollow keratin fibers (HF) and chemically modified soybean oil. High-speed microelectronics is facilitated by preventing the “rubber necking,” or slow-down of electrons on the printed wires through the use of low-k dielectrics. The unusual low-k value of the HF composite material derives both from the air (k = 1) in the hollow microcrystalline keratin fibers (k = 1.7), and the triglyceride molecules (k = 2.7), and is in the range of 1.7 to 2.7, depending on the HF fraction. These values are lower than that of the conventional silicon dioxide (k = 3.8 to 4.2) or epoxy dielectric insulators. Also, the HF dielectric is lightweight (SG < 1) and rigid (Modulus > 2 GPa), with fracture toughness (1.0 MPa m1/2) and approximates the shape and feel of a silicon dioxide insulator. The coefficient of thermal expansion (CTE) of the new material (67.4 ppm/°C) is low enough for electronic materials applications. Multi-Chip-Module circuit printing results suggest that the low-cost composite made with HF (from avian sources) and plant oil (from soybean) has the potential to replace the dielectrics in microchips and circuits boards in the ever-growing electronic materials field, in addition to many applications as new lightweight composite material.