A Study on the Dynamic Bending Reliability of Chip-in-Fabrics(CIF) Packages Using Anisotropic Conductive Films (Acfs) Materials For Flexible Electronic Applications

In this study, flexible Chip-In-Fabric (CIF) assemblies using anisotropic conductive films (ACFs) and cover layer structure were demonstrated. Fabric substrates were fabricated by Cu pattern lamination method with additional Electroless Nickel Immersion Gold (ENIG) metal finish before laminating onto the fabrics. Thermo-compression (T/C) bonding method was used to bond the $50\ \mu\mathrm{m}$-thick Si chip on the fabric substrates using ACFs. After T/C bonding, stable ACFs joint interconnection was formed between chips and substrates. After polymer cover layer structure was applied, the minimum bending radius before chip crack drastically decreased down to 10 mm radius. In addition, a dynamic bending test was performed to evaluate the dynamic bending reliability of the CIF assemblies, and cross-section SEM analysis and digital image correlation (DIC) method were used to analyze the bending test results.