A Fine Pitch Interconnection Method for High Frequency λ-Spaced Linear Arrays Using Microflex Technology

Abstract

High frequency arrays working with frequencies above 15 MHz will be more and more integrated in industrial and medical applications. They are interesting because of their resolution and capability for real-time imaging especially in catheters and other small devices.

The electrical interconnection of the single elements of a fine pitch array is one of the most challenging tasks in array technology. To be acoustically invisible the thickness of interconnection layers should not exceed 1/10 of the wavelength. Common flexible circuits surpass this limitation and are not easy to adapt to the acoustic device.

In this presentation a technology will be presented which allows to interconnect elements with a spacing down to 75μm using the Fraunhofer MICROFLEX (MFI) technology for backside contact and sputtering for front side contact with low acoustic influence. The MFI technology allows a high flexibility in the design and shape.

This paper focuses on the influences and contributions of the PZT material concerning its surface, the consistence of the applied electrodes, sputtering and galvanic, as well as the influence of the structuring dicing process.