Eco-friendly In-mold Electronics using Polylactic acid

Abstract

This paper presents the feasibility of using polylactic acid polymer as the overmolding material in in-mold electronics (IME). IME represents a technology integrating flexible electronic circuits into plastics in the molding process. This approach reduces weight and material consumption and simplifies the process. The increasing applications and consumption of these products result in a growing problem of electronic waste (ewaste). This necessitates a transition towards eco-friendly in-mold electronics and responsible end-of-life solutions. Currently, the most widely used plastic in this industry is polycarbonate both as flexible substrate and molding material. This polymer is derived from petroleum-based sources. This contributes to the depletion of non-renewable sources and greenhouse gas emissions. By using biopolymers as molding material, we can potentially minimize the environmental impact associated with this type of e-waste. Polylactic acid (PLA) is a bio-based and biodegradable polymer derived from renewable plant sources. In this study, polylactic acid is used only as the overmolding material. Typically, in IME the flexible circuit is fabricated using printed electronic (PE) technology. However, due to challenges regarding the stability of assembled electronic components, a polyimide-copper (PI/Cu) flex circuit fabricated through conventional printed circuit boards (PCB) manufacturing line is used in this paper. The goal of this work is to investigate if the PLA can be separated from the flexible circuit as end-of-life strategy. The debonding strategy simplifies the reuse, refurbish, or recycle of each separated layer. The IME technology was validated by showing the functionality of two different types of test circuits to demonstrate proof of concept. The adhesive strength between flex foil and PLA was evaluated by the 180 degrees peel test method. At the end-of-life, the debonding of PLA and flex circuit is investigated. In review, this research focuses on optimizing the overmolding process for PLA, exploring the compatibility of the PLA molding with the functionality of electronic components, and assessing the end-of-life practice for IME.