Modularization of crystal resonators

Usage of crystal resonators

A crystal resonator generates clock signals in combination with an oscillation circuit.
Clock signals can be likened to handclaps. Electronic parts operate in synch with handclaps. The faster the handclaps, the higher the performance (processing speed) of electronic devices. For example, you may have seen “CPU: ** GHz” on the specifications table of a personal computer. This is the clock signal speed.
Quartz crystals are used in many electronic devices because they can readily generate fast and stable clock signals.

Modularization of crystal resonators

A crystal oscillator encapsulates a crystal resonator and an oscillation circuit in a ceramic package.
Thus, crystal resonators can be combined with various parts to add functions and achieve modularization. In addition to crystal oscillators, applications of crystal resonators include resonators equipped with thermistors in combination with temperature sensors and real time clocks in combination with time management function ICs.

Issues related to modularization

For modularization by mounting an additional part to a ceramic package as in the case of crystal oscillators, a special mounting space must be provided in a ceramic package to avoid contact with an oscillating quartz plate. This makes the structure of a ceramic package complicated, resulting in higher costs. While a quartz crystal is fixed to a ceramic package using an adhesive, an additional part must be fixed using a gold wire, requiring assembly based on a processing method different from that of the quartz crystal. Accordingly, the modularization process becomes complicated.

Modularization of the Arkh series

The structure of the Arkh series crystal resonators consists of three quartz plates sealed together. Because no ceramic package is used, modularization can be achieved easily only by mounting an additional part on top almost without changing the design and structure of crystal resonators.
For example, a crystal oscillator can be fabricated only by mounting an IC on top of a crystal resonator. The structure, processing method, and process are the same as those of the Arkh series crystal resonators, except for mounting of an IC.
If an additional part can be fabricated in the form of a wafer, it can be sealed as the fourth wafer, using the same sealing method for the Arkh series (wafer-level packaging technology), enabling mass production at low cost. In addition, if an additional part can be formed on the lid wafer or base wafer of the Arkh series crystal resonators, modularization can be achieved without increasing the product thickness.
Thus, the Arkh series offers flexible solutions to cope with the cost increase, which is an issue in conventional modularization.