Nihon Dempa Kogyo Co., Ltd.

Shigeyoshi Murase

Chisato Ishimaru

A crystal device has an area defined inside a ceramic case thereof, and this area is made larger to increase the design freedom for mounting of a crystal unit (crystal element) in the crystal device. The crystal device is configured such that at least one crystal element is housed in a ceramic case in a rectangular form as seen in plan view. The crystal device includes the ceramic case having a bottom wall and a frame wall, and whose cross section is formed to be concave, and a metal cover jointed to a metal ring provided at an end face of the opening of the ceramic case by seam welding, to hermetically encapsulate the crystal element therein. The crystal device is configures such that one of the widths of the long side and the short side of the metal ring is shorter than the other one.

Crystal device for surface mounting

A surface-mounted device includes a ceramic case, which has a concave portion formed by a bottom wall layer, a frame wall intermediate layer and a frame wall upper layer, and which houses at least a crystal element inside the concave portion. The ceramic case includes: arc-formed notched parts at outer circumference four corners thereof; and mounting terminals, which are extended to notched parts in the bottom wall layer among the notched parts, on an outer bottom face thereof. A radius of curvature of the notched parts in the frame wall intermediate layer is made identical to or greater than a radius of curvature of the notched parts in the bottom wall layer, and a radius of curvature of the notched parts in the frame wall upper layer is less than the radii of curvature of the notched parts in the bottom wall layer and the frame wall intermediate layer.

The surface-mount type crystal oscillator includes a container body made of laminated ceramics, having a flat bottom wall layer, a frame wall defining a recess and a step portion formed at an inner wall of the recess, a crystal blank fixed to the step portion, an IC chip fixed to an inner bottom surface of the recess and a pair of inspection terminals provided on outer side surfaces of the container body and used to measure a vibration characteristic of the crystal blank. The bottom wall layer is made up of a first layer making up an outer bottom surface of the container body and a second layer between the first layer and the frame wall, and the inspection terminals are formed so as to extend across an end face of the second layer and the outer side surface of the frame wall.

Surface-mount type crystal oscillator

A crystal device for surface mounting, in which a metal cover is jointed to the metal ring by seam welding, satisfies relationships A/A&#x3c;C/Cand B/B&#x3c;D/Dwhere Ais a length of a long side of the metal ring, Ais a length of a straight portion of a long side except for curved portions, Bis a length of a short side of the metal ring, Bis a length of a straight portion of the short side except for the curved portions thereof, Cis a length of a long side of the metal cover, Cis a length of a straight portion of the long side except for the curved portions thereof, Dis a length of a short side of the metal cover, and Dis a length of a straight portion of the short side except for the curved portions thereof.

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Saitama, Japan

Shigeyoshi Murase