Novel interconnection technology for flex-on-glass (FOG) applications

Interconnections using anisotropic conductive films (ACF) were dominant in applications for flat-panel displays. However, a novel bonding mechanism for flex-on-glass interconnection is presented. Using SBM (Solder Bump Maker) technology, SnAgCu solder bumps were created on a glass substrate with a uniform height. Then, the glass substrate is thermo-compression bonded with a flexible PCB using a multifunctional bonding material called “Fluxing underfill”. The interconnection using solder and underfill method was analyzed through cross-sectional SEM image. Contact resistance values in the order of 10^-4 Ω, which is about two times lower than that of the conventional ACFs, were obtained. Preliminary results on cross-section analysis and contact resistance measurement indicate the novel bonding mechanism using the Fluxing underfill has a potential for applications in display interconnections.