Jpn. J. Appl. Phys. 51 (2012) 07GC03 (3 pages) |Previous Article| |Next Article| |Table of Contents|
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Development of a Long-Focal-Range Annular Array Ultrasonic Transducer
Hitachi, Ltd., Hitachi, Ibaraki 319-1221, Japan
(Received November 20, 2011; accepted January 30, 2012; published online July 20, 2012)
Conventional annular array transducers designed with Fresnel divided elements have a limited maximum size of the aperture of the transducer. In this study, we designed and fabricated a prototype of a large-aperture annular array transducer to inspect next-generation semiconductors. A new annular array pattern was designed with a wide focal range and a large focal length using equal areas for the inner elements and equal stroke widths for the outer elements. The prototype was fabricated by epoxy bonding with a patterned metal electrode on a flexible printed circuit and a piezoelectric copolymer. As a result of evaluation, we obtained a fine spatial resolution below 100 µm and a narrow relative sensitivity variation of 6.5 dB for a large focal length and a wide focal range from 10 to 30 mm.
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