High frequency ultrasound transducers based on ceramic films

Abstract

A design and a manufacturing method of ultrasound transducers based on films of ferro-electric ceramic material is presented, the transducers being particularly useful for operating at frequencies above 10 MHz. The manufacturing technique can involve tape-casting of the ceramic films, deposition of the ceramic films onto a substrate with thick film printing, sol-gel, or other deposition techniques, where manufacturing methods for load matching layers and composite ceramic layers are described. The designs also involve acoustic load matching layers that provide particularly wide bandwidth of the transducers, and also multi-band operation of the transducers. The basic designs can be used for elements in a transducer array, that provides the frequency characteristics of the single element transducers, for array steering of the focus and possibly also direction of a pulsed ultrasound beam at high frequencies and multi-band frequencies.

1 . A method of electrical connection to the electrodes of an ultrasound transducer or transducer array that radiates and receives ultrasound waves through a front face into a load material, with a back face on the opposite side, where
 the hot element electrodes and a common ground electrode are accessible from said back face at conducting electrode pads, and   electrical connections between said electrode pads and other circuits are made at conductor pads on said other circuits with a glue between said electrode pads and said conductor pads, said glue containing conducting particles, and   the electrical connection between said electrode pads and said conductor pads is furthered by conducting humps on one of said electrode pads and conductor pads, and   by applying pressure to the connection, the distance between said humps and the opposite pad is made so small that said conducting particles in said glue provides via said humps electrical connection between said electrode pads and said conductor pads, while outside said conducting humps the conductivity of the glue is so low that no electrical connection is made.   
   
   
       2 . An ultrasound transceiver system comprising an ultrasound transducer or transducer array and at least one electronic integrated circuit chip, where
 the electrical connections for said integrated circuit chip are accessible at conductor pads at one side of said chip, and   electrical connections between said conductor pads and said transducer array is made according to  claim 1 .   
   
   
       3 . An ultrasound transceiver system according to  claim 2 , where the transceiver is connected to an ultrasound imaging system through a cable, the electrical wires of the cable being connected to the transceiver at cable connection pads in said conducting film structure, said cable wires being connected to said cable connection pads through one of soldering, and gluing with glue containing conducting particles. 
   
   
       4 . An ultrasound transceiver system according to  claim 3 , where stress relieve between the cable and the transducer is obtained by gluing the jacket of the cable to said backing material.