Deformation characteristics and resistance distribution in thermoforming of printed electrical circuits for in-mold electronics application

In-mold electronics (IME) is a novel manufacturing technology which combines printed electronics and film insert molding to produce electronics-integrated plastic components. Basically, the IME process includes printing, thermoforming, and injection molding. During the thermoforming process, the printed circuit undergoes deformation which results in a variation of the electrical resistance of the circuit, and, therefore, the thermoforming process is one of the important processes which determine the performance of the IME product. In this regard, this study aims to investigate the details of the resistance variation based on the deformation of the printed circuit during the thermoforming process. The deformation of the printed circuit is characterized experimentally and numerically, while a regression model is constructed to describe the relationship between deformation and electrical resistance of the circuit. Then, the electrical resistance distribution of the circuit after the thermoforming process is predicted based on the numerical results and the regression model, which is compared with experimental data. The effect of geometrical parameter is also investigated both experimentally and numerically.