Lignin as renewable raw material for applications in electronics

Abstract

Abstract. In the long term, renewable raw materials should be used as favorite materials for applications in the electronic industry, but very high specifications for substrate materials make the use of biopolymers in electronics difficult. In this work, thermoplastic lignin is used as renewable raw material for electronic applications, precisely for a substrate material for printed circuit boards (PCBs). The results show that lignin-based substrate materials in a thickness range of 0.5 mm respectively 0.8 mm can successfully be produced via film extrusion using a slot die followed by a calender unit. With a glass fiber reinforcement content of ~24 vol. %, the substrate material shows good mechanical behavior (tensile tests and falling dart tests). The water absorption and the adhesion of the copper foil are in the range of FR 4, which is the standard substrate material for printed circuit boards. However, the maximum operating temperature, the time to delamination and the coefficient of thermal expansion are below the values of FR 4. Nevertheless, the developed lignin based substrate material can successfully be used as a prototype circuit board in a non-automated process.

Lignin-Derived Carbon-Coated Functional Paper for Printed Electronics

“…This process produces over 50−70 million tons of lignin annually, 17,18 from which the 2% is used to make low-value-added products such as dispersing agents, binders, concrete additives, and animal feed. 19,20 Thus, lignin, as a valuable precursor, 21,22 has been receiving significant attention for its wide-scale use in various applications. 23−25 Till date, lignin-derived carbons have been applied as a resistive layer in electronics, substrates for printed circuit board boards, and electrodes in energy storage applications including batteries and supercapacitors.…”

“…23−25 Till date, lignin-derived carbons have been applied as a resistive layer in electronics, substrates for printed circuit board boards, and electrodes in energy storage applications including batteries and supercapacitors. 22,23 Converting lignin into graphitic carbon is especially advantageous due to its high phenolic content that leads to achieving higher carbon yields than those gained from the other main macromolecular wood compounds such as cellulose and hemicellulose. 26 Coated functional substrates are receiving interest in the applications of electromagnetic interference shielding and potential use in an electronic circuit, active-matrix displays, and static electrical dissipation.…”