Piezoelectric Hemispheres

Advanced Electro Ceramics

CeramTec is a world leader in the design and manufacture of complex electronic ceramic components and assemblies used in a wide range of applications and cutting edge technologies.

CeramTec’s Global Electroceramics Division specialises in the development and production of various hemisphere and focal bowl sizes, electrode and metallisation configurations. This range is fabricated from 33 available piezoelectric material formulations to address high power, sensitivity, stability needs in cryogenic temperatures as also in high temperatures and extreme pressure applications.

 

Applications include
  • Sonar transducers
  • Hydrophones
  • HIFU medical and industrial
  • Underwater communications

 

Features
  • Choice of metallisation (Silver, Nickel, Gold and others)
  • Evaporated and chemically deposited metallisation's available
  • Thickness frequency tuning available on request
  • Wide choice of PZT formulations
Typical Electrode Configurations

Hole in apex

Custom

Custom Focal Bowl

Other custom electrode configurations and metallisation’s are available on request.

Dimensional Range (Hemisphere/ focal bowl)
  • Outside Diameter/ Diameter from 6mm (0.24”) to 152.4mm (6”)
  • Wall thickness / Thickness from 1mm (0.04”) to 10mm (0.39”)

Parts can be produced to the size ranges shown, but not in every combination of dimensions expressed above.


Standard Mechanical Tolerances
  • Outside diameter/ diameter ± 0.150mm
  • Wall thickness / Thickness ± 0.05mm

Tighter mechanical tolerances are achievable but are dependent on the plate length, width and thickness.


Metallisation Type
  • Silver fired thick film - Evaporated Nickel
  • Electroless nickel - Gold flash
  • Tin - Evaporated Gold and others available on request
Typical Impedance Response Trace (Radial Resonance)

The above is a typical impedance trace measured on a dedicated analyser and depicting the resonance and anti-resonance points associated with the ring shaped component. This data allows the calculation of piezoelectric activity and other important characteristics required for the application.

Useful Equations

Capacitance

Static displacement

Planar coupling factor

Radial frequency

Voltage (static)

Mechanical quality factor

Thickness frequency

Effective coupling factor

Ceramic Testing

Appropriate statistical methods ranging from AQL’s to 100% testing are used on electrical parameters in accordance with EN-50324-1. A brief summary is provided in hard copy and typically includes low field measurements of capacitance, tan delta and the main parameters used to determine piezoelectric activity. Procedures other than this can be negotiated, and additional data requirements (electronic format, sample quantity, etc) are available on request.