Flex to flex bonding using anisotropic conductive film for imaging systems

Bonding and integration technologies in ultrasound probes are challenging due to space limitations. Flexible substrates, with the benefits of being bendable, small and allows 3D integration, is an excellent choice for signal transferring in such systems. We have chosen to use anisotropic conductive film (ACF) as interconnection technology and the quality and the reliability of a flex-ACF-flex bonding have been studied. The relationship between bonding force and contact resistance have been characterized including the effect of thermal cycling tests and humidity tests. The study shows that flex-ACF-flex is a robust bonding technique which has very good performance also after environmental tests and is well suited for interconnection in ultrasonic transducer probes.