Quantity (thickness) of electrode material

Currently, our company handles monitor crystals with three varieties of electrode material: gold, silver (chrome substrate), and alloy. Each has a different quantity (thickness) of electrode material. Please refer to the figure below. Monitor crystals with alloy electrodes have thicker electrode material deposited than those with gold electrodes. Because the electrode material is thick and soft, it acts as a cushion even after the client’s material has been deposited, and creates longer life without obstructing the crystal’s oscillation (thickness slip vibration).

Thickness slip vibration

Thickness slip vibration is one of the vibration modes of crystal oscillators (monitor crystals). Crystals, which are piezoelectric elements, are put under stress when electrical potential is applied. AT-cut oscillators are notable for producing stress in the direction of thickness. The figure below shows a typical thickness slip vibration in the cross-section of the element. The central area, with high charge density, has larger stress vibration.

Amplitude (frequency) changes with thickness. As thickness increases, amplitude grows larger, and the frequency value becomes lower.