Theoretical and experimental characterization of process-induced thermal-mechanical behaviors of an ultra-thin chip-on-film assembly

In this study, an advanced flexible electronics technology, termed as the ultra-thin chip-on-film (UTCOF) technology, is introduced. The technology implements an epoxy-based anisotropic conductive film (ACF), a composite materials composed of an adhesive polymer resin and conductive particles of metal-coated polymer particles, to form fine-pitch and reliable interconnects of IC bumps on flex substrates. Basically, yield and reliability that determine the feasibility of any proposed novel technology are two of the most critical and essential issues. Prior to attempting to better the reliability of the technology, it is necessary and essential to well comprehend its thermal-mechanical behaviors. Hence, the main objective of the study is to investigate the process-induced thermal- mechanical behaviors of the UTCOF technology during the ACF bonding process. Furthermore, to undertake the thermal-mechanical modeling, a process-dependent simulation methodology that integrates both thermal and thermal-mechanical finite element (FE) analyses together with a "death-birth" meshing scheme is proposed. The validity of the modeled results is verified through a micro thermocouple experiment, a warpage measurement using a Micro Figure Measurement Instrument and laser scanner.