HP Labs Technical Reports

A 2.5 MHz 2D Array with Z-Axis Backing

Greenstein, Michael; Lum, Paul; Yoshida, Henry; Seyed-Bolorforosh, Mir Said

HPL-97-12

Keyword(s): medical acoustics; ultrasonics; imaging transducers; two dimensional array

Abstract: The design, fabrication and initial characterization of a prototype fully lambda/2 sampled, 2.5 Mhz, 50 x 50 element 2D array for cardiac medical imaging applications is presented. The array utilizes a novel Z-axis electrically conductive backing layer to provide both appropriate acoustic attenuation, and an anisotropic electrical interconnect for the individual acoustic elements in the 2D array. A modular, demountable Pad Grid Array (PGA) interconnect is used to connect to the backing. The PGA is capable of terminating the full 2500 element array at a spatial pitch of 300 microns. Measurements are presented on the electrical impedance, directivity and cross talk of the 2D array module, as well as the pulse echo properties of the 2D array elements exited through the Pad Grid Array interconnect system. The single element directivity is measured to be 35 degrees, while the nearest neighbor electrical cross talk is measured at -42 dB. The pulse echo waveform has a fractional bandwidth of 50%.

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