Low-dielectric thermosetting resins derived from polysaccharide unsaturated esters

Printed circuit boards (PCBs) contain metals and plastics, with the latter often incinerated after disposal, leading to carbon dioxide emissions. This study focuses on developing biomass-based thermosetting resins derived from polysaccharides. Cellulose and alpha-1,3-glucan were introduced with unsaturated (2-butenoate) and saturated (hexanoate) ester groups to achieve appropriate properties for PCB applications. The synthesized polysaccharide esters, cellulose-2-butenoate-hexanoate and alpha-1,3-glucan-2-butenoate-hexanoate, demonstrated thermoformability at 150 degrees C, suitable for being laminated on circuit lines. After heating at 220 degrees C for 1 hour, the unsaturated parts of the polymers crosslinked, increasing the glass transition temperature to over 230 degrees C, making them potentially durable for the soldering process. The dielectric constant and dissipation factor of the crosslinked resins ranged from 2.5 to 2.7 and 0.012 to 0.014, respectively, outperforming conventional epoxy resins to reduce transmission loss. Additionally, the crosslinked films exhibited robust mechanical properties with tensile strengths exceeding 50 MPa. These results indicate that polysaccharide unsaturated esters are promising for use as PCB insulating resins, providing a sustainable alternative to petroleum-based materials.