Are Piezoelectric material RoHS Exempted?

RoHS Directive: Per Directive 2002/95/EC Lead in electronic ceramic parts (i.e. Piezoelectronic material) exempted from the requirements of Article 4(1) , Section 7

What is PZT 5A?

PZT5A is a soft piezoelectric ceramic used in applications requiring moderately high displacement and sensitivity with a Curie point above 300 deg C. Some examples of applications are inkjet print heads and vibration control and actuators for high temperature applications.

What is PZT 5H?

PZT5H is a soft piezoelectric ceramic used in applications requiring high dielectric, high displacement and high sensitivity. Some examples of applications are medical ultrasound, hydrophone sensors.

Why is low porosity important?

Low porosity improves material strength, dielectric breakdown, allows machining of fine features and thin wafers. It also enables material to have consistent electrical properties.

Why is high mechanical strength important?

High mechanical strength is important because a piezoelectric element changes shape as a component of its function. Poor mechanical strength can give rise to fatigue, decrease in properties, and perhaps catastrophic failure.

Why are small dimensions important?

Small dimensions are important because of the drive towards miniaturization in sensor and actuator markets. This also allows the use of this material in ceramic/polymer composites.

Why is high aspect ratio important?

High aspect ratio is important because it allows deep channels to be reliably cut into the ceramic. This could be used in inkjet or any fluid pump application where precise volume of liquid is required. This is also important in medical ultrasound applications where element size is decreasing to allow for better image resolution.

What is sensitivity?

Sensitivity refers to the response of a piezoelectric material to an applied electrical or mechanical stimulus. The d_ij and g_ij constants represent sensitivity.

d_ij is the charge constant, which represents strain per applied electric field (m/V) or polarization per applied stress (C/N)

• Strain/Applied field: (m/m)/(V/m) = m/V
• Polarization/Applied stress: (C/m²)/(N/m²) = C/N

g_ij is the voltage constant, which represents the electric field produced by an applied stress (Vm/N) or the strain produced by electric displacement (m²/C).

• Electric Field/Applied Stress: (V/m)/(N/m²) = Vm/N
• Strain/Electric displacement: (m/m)/(C/m²) = m²/C

Why is high sensitivity important?

Higher sensitivity (larger d_ij or g_ij constant) represents a larger response and improved signal-to-noise ratio for a given stimulus. Selecting the proper piezoelectric material for a given application often involves a trade-off between sensitivity and other properties such as Curie point or Dielectric constant. For example, materials with the highest charge constant (d_ij) have lower Curie points than materials with lower charge constants.

Why is high sensitivity needed in medical ultrasound?

The piezoelectric material both projects and senses the acoustic wave. High sensitivity is necessary to maximize the signal-to-noise ratio for the returned acoustic wave.

Why is high displacement needed in inkjet, speakers, etc.?

In these applications it is generally necessary to minimize the electric field needed to achieve the desired response. Thus, high displacement (d_ij) materials allow a lower drive voltage to be used.