Abstract: A process of bonding crystalline quartz plates in a plate assembly of a quartz crystal resonator is provided. The plate assembly includes a base plate, a resonator plate, a cover plate, a first silver and indium alloy layer between the base plate and the resonator plate, and a second silver and indium alloy layer between the resonator plate and the cover plate. The process of bonding the plates in the plate assembly includes the steps of depositing in sequence on base plate face and on the cover plate face, a layer of chromium, a layer of silver, and a layer if indium, and also includes the steps of depositing in sequence on two opposite faces of the resonator plate, a layer of chromium, and a layer of silver, and also includes the steps in sequence of sandwiching the resonator plate between the base plate and the cover plate to form a plate assembly, then evacuating the plate assembly, compressing the plate assembly, and heating the plate assembly to about 310 degrees centigrade for several hours.