PZT Based Micro Structures

Lead Zirconium Titanate, or PZT, is a piezoelectric ceramic that can be machined in various ways to produce an increasing variety of high-tech products. In particular, PZT is a popular choice for producing a wide range of components that need to transmit and receive acoustic sound waves or components that need to produce small actuating movements. Common applications of each include:

Acoustic:

  • Sonar arrays for underwater exploration and sea bed mapping (see image above)
  • Sonar and ultrasound arrays for sea and air defenses
  • Medical ultrasound
  • NDT – non destructive testing
  • Flow measurement and control

Actuating:

  • Micro-pumping as found in digital inkjet print heads
  • Micro and nano positioning
  • Fibre optic guidance systems
  • Vibration damping

Loadpoint Expertise

Loadpoint have been machining PZT for over 20 years. During this time we have partnered with a number of organisations to prototype and develop devices for products that have achieved “best in class” status. We not only machine PZT materials in our Loadpoint Production facility but also design and manufacture machines that are used by other PZT experts. This means we not only understand how to machine PZT but we also have in-depth knowledge on how to control and optimise machine systems to produce market leading PZT products. Add to this our knowledge of manufacturing process & control and our clients therefore have an expert partner in Loadpoint, from prototype to full production.

Sonar and Ultrasound

For acoustic PZT applications, PZT is often used in composites form. Here, the PZT is encapsulated in a resin or polymer material to give it additional properties such as better acoustic impedance and coupling or increased bandwidth.

The image on the right gives a schematic description of the 1-3 composite fabrication process. “1-3” is a category of composite that refers to the fact that the PZT pillars are able to vibrate in 3 dimensions. 1-3 composites are commonly used for most sonar and ultrasound requirements. The process involves dicing the pillars into the PZT, then filling the structure with a resin or polymer, then removing the remaining PZT plate by backgrinding. What is now left is a composite array of vertical, isolated pillars. A smaller number of relatively large pillars (2-4mm square) are used for lower frequency sonar whereas higher frequency ultrasound tends to use a much higher number of minute pillars (down to 50µm square or even smaller). Finally, the specific frequency to which the array transmits and receives ultrasound is determined by the thickness the array is ground down to, the last step in the machining process before trimming to size. The next stage in the overall process is to apply a thin film electric coating to the material to enable electric interfacing.

Capabilities

Dicing, potting or backfilling (applying the composite material), backgrinding and grinding to frequency, application of metallic thin-films, scribe dicing of the metallic layer to cause electric isolation between pillars.

Loadpoint Production has the facilities to produce and certify PZT composites from thickness down to 150µm up to thickness well beyond 25mm.

Digital Print Heads

Digital print heads are made by producing a series of linear cuts into bonded PZT plates. The addition of a metallic layer enables electrical contact between the two faces.

Capabilities

Dicing
Via hole drilling

Print head production is normally a high volume operation and a critical success factor therefore is guaranteeing long-term stability of the dicing process. Loadpoint have leading expertise in this respect.