A novel flex circuit area-array interconnect system for a catheter-based ultrasound transducer

Flexible circuitry is uniquely suited as an interconnect media for medical sensor area-array interconnection due to fine trace patterning capability, microvia technology and multilayer construction techniques. This paper describes a novel high density area-array flex interconnect system for a catheter-based 3-D ultrasound imaging transducer. The catheter device consists of a two dimensional array of piezoelectric transducers operating at 5 MHz arrayed in a 12 × 16 matrix at 150 micron pitch. A six-layer flex substrate featuring 25 micron thick polyimide layers patterned with 25 micron wide trace features was fabricated as the first level interconnect connecting the sensor array to a cable system. The entire sensor/cable/flex system is placed within a seven French (2.33 mm o.d.) catheter. The array is used to image the internal surface of the heart from within the heart chamber itself. The flex interconnect features UV laser drilled via-in-pad technology with 50 micron vias and advanced registration technology. The top layer of the flex interconnect serves as a sacrificial layer which is post-patterned to provide acoustical and electrical isolation of the array elements after electrically interfacing the flex to the piezoelectric array. The flex circuit fabrication process and interconnect will be discussed.

Duke Scholars

Author Stephen William Smith Biomedical Engineering