Method of making an ultrasonic transducer
View Patent ↗A leaded piezoelectric transducer element is attached to the inside of the end surface of a closed-end cylindrical container such as a plastic cup. The outside end surface of the cup is intended for exposure to a fluid. The required components to isolate and/or resonate with the piezoelectric element are added, after which a rigid encapsulant is formed in the cup to make a single solid assembly strong enough to be clamped. The end of the cup is then thinned to yield a thin, compliant, and environmentally protecting acoustic window.
1. A method of making an ultrasonic transducer, the method comprising the steps of:
a) providing a closed-end cylindrical member having an end portion extending between an internal end surface and an external end surface;
b) attaching a piezoelectric element assembly to the internal end surface of the cylindrical member;
c) encapsulating the piezoelectric element assembly; and then
d) thinning the end portion of the cylindrical member by removing material from the external end surface thereof to yield an acoustic window.
2. The method of claim 1 wherein the internal end surface is flat and perpendicular to a side wall of the cylindrical member.
3. The method of claim 1 wherein the piezoelectric element assembly is attached to the internal end surface by a thin epoxy layer.
4. The method of claim 1 wherein the piezoelectric element assembly comprises an isolating member distal from the internal end wall.
5. The method of claim 1 wherein the encapsulating step comprises covering the piezoelectric element assembly with a medium-hard epoxy.
6. The method of claim 1 wherein the step of thinning the end portion comprises clamping the cylindrical member and removing material from the end portion thereof.
7. The method of claim 1 wherein the acoustic window is no more than 0.010″ thick.
8. The method of claim 1 wherein the acoustic window is substantially 0.005″ thick.
9. The method of claim 1 comprising steps after the thinning step of:
e) connecting external leads to the piezoelectric element assembly; and
f) adding additional encapsulant to cover the connections so formed.