Effect of Acrylic Structural Adhesive as a Joint Reinforcement on Film Deformation during the Thermoforming Process for In‐Mold Electronic Devices

In‐mold electronic (IME) technology enables the production of devices with 3D‐shaped electronic surfaces, where adhesives play a crucial role. Conductive adhesives are responsible for maintaining conductivity, while structural adhesives enhance functionality. Previous studies have shown that conductive adhesives influence the film deformation during the thermoforming process, impacting device functionality. Although it is presumed that structural adhesives have a similar effect, this has not been thoroughly investigated. This study compares hybridized samples using structural adhesive under different conditions to those with only conductive adhesive, analyzing stretching and thickness reduction during thermoforming. Results demonstrate improved functionality and variations in deformation. A greater amount of adhesive reduces stretching near its application, while increases as it recedes from the adhesive. However, altering the conventional adhesive disposition patterns leads to greater stretching around the adhesive. These findings indicate that the presence, amount, and disposition of structural adhesive significantly affect film behavior during processing. These factors must be carefully considered in the design of IME devices to optimize functionality.