High-density flexible interconnect for two-dimensional ultrasound arrays

We present a method for fabricating flexible multilayer circuits for interconnection to 2-D array ultrasound transducers. In addition, we describe four 2-D arrays in which such flexible interconnect is implemented, including transthoracic arrays with 438 channels operating at up to 7 MHz and intracardiac catheter arrays with 70 channels operating at up to 7 MHz. We employ thin and thick film microfabrication techniques to batch produce the interconnect circuits with minimum dimensions of 12-/spl mu/m lines, 40-/spl mu/m vias, and 150-/spl mu/m array pitch. The arrays show 50-/spl Omega/ insertion loss of -60 to -84 dB and a fractional bandwidth of 27 to 67%. The arrays are used to obtain real time, in vivo volumetric scans.