US 6,088,894 AGranted

Methods of making composite ultrasonic transducers

AssigneeTetrad Corporation

InventorsClyde G. Oakley, Stephen J. Douglas

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Abstract

An improved composite ultrasonic transducer, and elements therefor, which may be made autoclavable, and a method of making these elements. A number of planar precursors comprising strips of piezoelectric ceramic material separated from one another by a polymer material are stacked one above another with the ceramic strips aligned with one another, and with electrical conductors disposed between each of the planar precursors. These precursors are then bonded to one another, to form a bonded assembly. The bonded assembly is then slit along parallel lines perpendicular to the direction of elongation of the ceramic strips, subdividing the strips into individual ceramic members and also subdividing the planar conductors, forming ribbon-like conductors extending between opposite sides of the array. The saw kerfs are filled with a hardening polymer material. The ribbon-like conductors reaching the edges of the assembly are then connected electrically in parallel, reducing the capacitance of the individual emitters. Criteria for selection of the materials of the ceramic members, the conductors, and other components of the transducer, and their relative proportions are given which allow the transducer to be steam-autoclavable.

Claims27

Dependent claims

A method of fabrication of an element of an ultrasonic transducer, said element comprising an array of piezoelectric emitters spaced from one another by a polymer matrix, each emitter comprising an equal number of stacked individual ceramic members electrically connected to one another by planar strip-like electrical conductors disposed therebetween and extending continuously between opposed edges of said array, such that each of said members can be excited simultaneously by a drive signal applied to said conductors, said method comprising the steps of:

forming a number of planar precursors, each comprising a plurality of parallel elongated ceramic strips spaced from one another by strips of a polymer material;
providing a continuous layer of the material of said electrical conductors on at least one of opposed planar faces of each said planar precursor;
stacking a number of said planar precursors equal to the number of elements desired in each of said emitters atop one another, such that the parallel elongated ceramic strips of each of said planar precursors are aligned with respect to one another;
bonding said planar precursors to one another, forming a bonded assembly wherein the conductors disposed between opposed planar precursors are in good electrical contact with the aligned ceramic strips of both;
cutting through said bonded assembly along a number of parallel cutting lines perpendicular to the direction of elongation of said parallel elongated ceramic strips, whereby each of said parallel elongated ceramic strips is subdivided into a number of members spaced from one another by kerfs remaining after said cutting step, and said conductors are simultaneously divided into a number of strip-like conductors extending between opposite edges of said assembly;
filling the kerfs remaining after said cutting step with a hardening polymer material;
and
providing electrical connections to said conductors at the edges of the assembly.

5 more elements

A method of fabrication of an element of an autoclavable ultrasonic transducer, said element comprising an array of piezoelectric ceramic members spaced from one another by a matrix of a hardening polymer material, ones of said members being electrically connected to one another in one direction by strip-like planar electrical conductors comprising layers of one or more of gold, silver, chromium, copper, or nickel disposed therebetween and extending continuously in one of said dimensions between opposed edges of said array, such that each of said members can be excited simultaneously by a drive signal applied to said conductors, said method comprising the steps of:

forming at least one planar precursor comprising a plurality of parallel elongated ceramic strips spaced from one another by strips of said hardening polymer;
providing at least one continuous layer of the material of said electrical conductors on at least one of opposed planar faces of each said planar precursor;
forming an assembly of all of said at least one planar precursors;
cutting through said assembly of said planar precursors and said at least one conductive layer along a number of parallel cutting lines perpendicular to the direction of elongation of said parallel elongated ceramic strips, whereby each of said parallel elongated ceramic strips is subdivided into a number of individual members spaced from one another by the kerfs remaining after said cutting step, and said continuous layers of the material of said electrical conductors are simultaneously divided into a number of strip-like conductors extending between opposite edges of said assembly;
filling the kerfs remaining after said cutting step with a hardening polymer material;
and
providing electrical connections to said conductors at the edges of the assembly.

4 more elements

Dependencies are inferred from the claim text.