In-mold electronics applications: the control of ink properties through the use of mixtures of electrically conductive pastes

Polymer thick films compatible with a thermoforming process are the key components to realize the next generation of human–machine interface and lighting with a 3D custom shape through an in-mold process. The purpose of this study is to demonstrate that a tailored combination of commercial pastes can offer the manufacturer more freedom in developing smart electronic devices. A four-point probe instrument was used to measure the resistivity of the printed circuit. We used the same formed printed sample to estimate the level of elongation under the thermoforming process due to the all-in-one screen design developed for the study. The important objective of this work was to form a paste which should withstand such operations without losing physical properties such as conductivity or adhesion or getting lines cracked.