Effects of interfacial bonding strength on the formation of conductive anodic filament in polyphenylene oxide/glass fiber laminates

The formation of conductive anodic filament (CAF) inside printed circuit boards (PCBs) is one of the major failure modes related to the long-term reliability of electronic devices. In this paper, the relationship between susceptibility to CAF formation and glass fiber/resin interfacial bonding strength of a thermosetting polyphenylene oxide (PPO)/glass fiber composite system was investigated. Laminates with different interfacial bonding strengths were prepared by coating glass fibers with different silane coupling agents. Interlaminar shear strength (ILSS) of the PPO composites with silane-treated glass fibers has been improved by around 30 %, compared to the PPO/glass fiber composite without silane treatment. An accelerated response to CAF susceptibility was realized by substantially reducing the hole wall to hole wall distance of PCB to 5mil and 7 mil. By correlating the test results of interlaminar shear strength, haloing effect and susceptibility to CAF formation, it is confirmed that the CAF resistance of PCBs is positively correlated with the glass fiber/resin interfacial bonding strength.