RU2632268C2 - Quartz generator - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: quartz generator contains a cermet housing with a mounting platform, a piezoelectric element and a one-chip generator circuit, one-chip integrated generator circuit is placed on an additionally added ceramic plate with conductive paths, on which holders with a piezoelement are fixed with a conductive adhesive, and installed with glue on the mounting platform. The contacts of the single-chip integrated circuit are connected by welding with conductors with contacts on the ceramic plate.

EFFECT: creation of a highly stable miniature quartz surface-mounted generator, whose piezoelectric element is mechanically decoupled from the generator housing.

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Description

The invention relates to the field of electronics and can be used in the development of miniature crystal oscillators for surface mounting.

Currently, single-chip integrated circuits of crystal oscillators have appeared that work with AT cutoff resonators. For operation of generators based on this scheme, only a piezoelectric element or resonator is needed. In the case of using a piezoelectric element (a resonator without a housing), the overall dimensions become the smallest possible, however, a decrease in the size of the piezoelectric element is associated with the appearance of frequency jumps at individual ambient temperatures and a large influence of the attachment points of the piezoelectric element on the quality factor and vibration stability. When the piezoelectric element is mounted directly in the ceramic-metal case, the temperature-frequency characteristic of the product is usually strongly distorted due to the difference in the linear expansion coefficients of quartz and the case.

Closest to the proposed one is a generator [1], containing a piezoelectric element mounted on the recesses of the ceramic-metal casing, and a single-chip integrated circuit of the generator installed on the installation site.

The disadvantage of the prototype is the lack of mechanical isolation between the body of the entire product and the piezoelectric element, which affects the temperature-frequency characteristic of the generator.

The objective of the invention is the creation of a highly stable miniature quartz oscillator surface mounted, the piezoelectric element of which is mechanically isolated from the generator housing.

The problem is achieved by introducing a quartz oscillator containing a ceramic-metal casing with a mounting pad, a piezoelectric element and a single-chip oscillator circuit, according to the invention, a single-chip integrated circuit of the generator is placed on an additional ceramic plate with conductive tracks, installed with glue on the mounting pad of the ceramic-metal casing, while the contacts of a single-chip integrated circuit are connected by welding with conductors with contacts on a ceramic the main board and the ceramic-metal case, and on the ceramic board with conductive adhesive, holders with a piezoelectric element of the ceramic board, which is a buffer between the generator body and the piezoelectric element, are placed. Also on this board is an integrated circuit of a quartz oscillator and conductive paths.

The design of the proposed crystal oscillator is presented in the figure. It is a ceramic-metal casing 1, on the mounting site of which a ceramic board 2 with conductive tracks is fixed with glue. A single-chip integrated circuit 3 is installed on the ceramic circuit board, the contacts of which are connected by welding wire with the contacts on the ceramic circuit board and the ceramic-metal case, and holders 4 with a piezoelectric element 5 are placed, which are fixed with conductive adhesive. Sealing occurs by seam-roller welding of the cover 6 and the housing 1.

The operation of the inventive quartz generator is based on the fact that when the ambient temperature changes, the ceramic-metal case changes its geometrical dimensions, and a ceramic board installed on the mounting pad and fixed in the central zone reduces the effect of changing the case dimensions on the location of the holders. The holders, in turn, reduce their effect on the piezoelectric element when the ambient temperature changes. Thus, there is a double mechanical isolation of the piezoelectric elements from the ceramic-metal casing, due to which the repeatability of the temperature-frequency characteristics of the generators is achieved.

Example

Crystal oscillators were manufactured at a frequency of 20 MHz according to the proposed design. After manufacturing, the temperature-frequency characteristics of the finished products were measured. In the range of operating temperatures from minus 60 to plus 85 ° С, the temperature-frequency characteristics of the generators had similar, predictable values and did not have frequency jumps. That is, in this design, the temperature-frequency characteristic of the mounted piezoelectric element and the generator is entirely determined by the cutting angle, and not by the type of housing used, conductive glue and the installation method.

Information sources

1. US patent US 6452460 B2, 09/17/2002.

Claims (1)

A quartz oscillator comprising a ceramic-metal casing with a mounting pad, a piezoelectric element and a single-chip oscillator circuit, characterized in that the single-chip oscillator circuit is placed on an additional ceramic plate with conductive paths, on which holders with a piezoelectric element are fixed with adhesive and installed with glue on the mounting platform, wherein the contacts of a single-chip integrated circuit are connected by welding with conductors to the contacts on the ceramic board.

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