JP2000134058A - Piezo-oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make this oscillator short according to a single seal structure and to execute frequency fine adjustment by hermetically sticking a metal cover to the upper face of the outer frame of a package body in a state in which an inner package where a crystal resonator is mounted in an unsealed state is fixed onto the inner step of a recessed part of the package body. SOLUTION: A step 33 is provided in a recessed part 32 formed on the upper face of a package body 31 made of ceramics, an inner package 34 is fixed onto the step 33 and a circuit part 36 is also mounted on the wiring pattern on an inner bottom 35. A crystal resonator 41 is supported in cantilever by binding material 40 such as a conductive adhesive over the package 34. In such a case, the package 34 functions as a simple pedestal and its upper plane is not sealed but is left open. The package 34 to which the resonator 41 is preliminarily attached is adhered and fixed onto the step 33 of the recessed part, and then, a metal cover 39 is hermetically fixed to the upper face 37 of the outer frame of the body 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric oscillator having a crystal resonator and circuit components mounted in a package, and more particularly, to a piezoelectric oscillator capable of realizing a low profile, a simple structure, and a simple manufacturing process. .

[0002]

2. Description of the Related Art A piezoelectric device having a structure in which a piezoelectric vibrating element such as a quartz vibrating element is hermetically sealed in a package is used to generate a reference frequency in communication equipment such as a mobile phone and a pager, and electronic equipment such as a computer. It is used as a source, filter, etc. Also, the oscillator as a piezoelectric device is
For example, a configuration is provided in which a recess opening is hermetically sealed with a metal lid in a state in which a piezoelectric vibrator and a circuit element are housed in a recess formed on the upper surface of a package body made of ceramic or the like. FIG. 3 is a longitudinal sectional view showing the structure of such a conventional crystal oscillator as a piezoelectric oscillator. This piezoelectric oscillator has a step 3 in a concave portion 2 formed on the upper surface of a package body 1 made of ceramic, fixes a quartz oscillator 4 on the step 3 and a circuit component on a wiring pattern on an inner bottom surface 5. 6 is installed. Further, a metal cover 9 is provided using a seam ring 8 provided on an upper surface 7 of an outer frame of the package body 1.
Is welded. The crystal unit 4 supports the crystal unit 15 in a cantilevered state via a conductive adhesive 14 on a step 13 in a recess 12 of the inner package 11, while holding a metal on the outer frame upper surface of the inner package 11. It has a configuration in which it is welded with the lid 16 covered. In this type of piezoelectric oscillator, it is only necessary to incorporate the crystal unit 4 which is sealed and completed in a clean environment into the package body 1.
There is an advantage that abnormal oscillation due to a defect such as minute dust such as dust adhering to the crystal resonator element is unlikely to occur. In general, an annealing step of leaving the crystal resonator 4 in a high-temperature environment for a long time in order to stabilize the aging characteristics of the crystal resonator and find an aging defect is performed on the crystal resonator 4 alone and then incorporated into the package body 1. .
However, because of the double seal structure using the two metal lids 9 and 16, there is a disadvantage that the cost is increased.
Further, since the structure is such that the crystal unit 4 is housed in the package body, there is a disadvantage that the overall height of the package increases.

Next, the piezoelectric oscillator shown in FIG.
After the circuit component 6 is mounted thereon, the crystal vibrating element 21 is placed on the step 3 in the package body 1 via the conductive adhesive 20 or the like.
Is a single seal type in which only one metal lid 9 is used as a sealing means. In this type, the height of the piezoelectric oscillator can be reduced by an amount that does not require an inner package for accommodating the crystal resonator element 21, and the cost can be reduced because of the single seal structure. However, since the circuit component 6 is housed in the package body in addition to the crystal resonator element 21, if the annealing is performed on the crystal resonator element 21, the circuit component 6 is also exposed to a high temperature. Cannot be performed, and the aging characteristic of the oscillator deteriorates. When an AT-cut quartz plate is used as the quartz vibrating element 21, the plate thickness of the plate 21a including the electrodes 21b and 12c is closely related to the vibration frequency. When adjusting the frequency of the crystal vibrating element 21, the thickness of the base plate 21a is set in advance to be smaller than the thickness for obtaining vibration of the target frequency, and the amount of metal to be an electrode film is reduced. An operation of approaching the target frequency while adjusting is performed. That is, in FIG. 4, the frequency of the crystal vibrating element 21 in the crystal oscillator in a state before the metal cover 9 is covered is measured in advance, and when the measured frequency is shifted to the higher side, this oscillator is vapor-deposited. A metal is added to the electrode 21b on the upper surface of the quartz-crystal vibrating element 21 from the opening side of the concave portion 2 by being put in the tank. This operation is performed while monitoring the frequency. When the optimum frequency value is reached, the deposition is terminated. Since such a vapor deposition operation needs to be performed in a pinpoint manner, it is necessary to use a high-precision fine mask. It turns to the lower side and adheres to the circuit components and the pattern on the inner bottom surface, so that there is a high possibility of becoming a defective product. Further, it is necessary to clean the inside of the package body using a cleaning liquid before sealing the crystal unit.However, if the cleaning liquid is caused to flow in with sufficient force to remove fine dust remaining in the recessed portion, the circuit components are removed. This causes problems such as cutting of the bonding wire connected to the wiring pattern.

[0004]

The problem to be solved by the present invention is that the package body is sealed with a metal cover in a state where the crystal unit and the circuit components which are not hermetically sealed are housed together in the package body. In a piezoelectric oscillator with a hermetically sealed structure, an annealing process for the crystal vibrating element, while reducing the height of the package body and reducing the cost,
It is an object of the present invention to provide a piezoelectric oscillator capable of performing a cleaning step and a metal film deposition step for fine frequency adjustment.
That is, the crystal oscillator package with the crystal resonator package mounted on the step inside the recessed part of the package body and the circuit components mounted on the inner bottom face has disadvantages such as an increase in height and an increase in cost due to the double seal structure. Because of this, a single-seal type has been proposed, in which a quartz resonator element is directly mounted on the step inside the recessed part of the package body and circuit components are mounted on the inner bottom surface to reduce the height and cost. In the single seal type oscillator described above, it is impossible to clean and anneal the crystal vibrating element, so that there is a disadvantage that it is difficult to stabilize characteristics. Further, there is another problem that it is difficult to finely adjust the frequency while depositing a metal on the upper surface of the crystal resonator. According to the present invention, a metal lid is hermetically fixed to an upper surface of an outer frame of a package body in a state where an unsealed inner package on which a crystal resonator element is mounted is fixed on a step inside the concave portion of the package body. An object of the present invention is to provide a piezoelectric oscillator capable of reducing the height by a single seal structure and performing fine adjustment of frequency by cleaning, annealing, and metal deposition of a quartz oscillator.

[0005]

In order to solve the above-mentioned problems, a first aspect of the present invention provides a package body having a concave portion on an upper surface, a circuit component mounted on a wiring pattern on the inner bottom surface of the concave portion, and An inner package mounted on a step formed at a position higher than the inner bottom surface of the recess; a piezoelectric vibrator mounted in the recess on the inner package; and a seal fixed to the upper surface of the outer frame of the package body to seal the recess. And a metal lid for stopping. The invention according to claim 2 is characterized in that the height of the outer frame of the inner package is reduced to at least the same height as the upper surface of the crystal resonator element.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. 1A and 1B are a cross-sectional view and an exploded view showing a package structure of a crystal oscillator as one embodiment of the piezoelectric oscillator of the present invention. This crystal oscillator has a step 33 in a concave portion 32 formed on the upper surface of a package body 31 made of ceramic, and fixes an inner package 34 on the step 33 and a circuit component 36 on a wiring pattern on an inner bottom surface 35. It is equipped with. Furthermore, the seam ring 3 provided on the outer frame upper surface 37 of the package body 31
The metal lid 39 is welded by using the reference numeral 8. A quartz resonator element 41 is cantilevered on the inner package 34 by a binder 40 such as a conductive adhesive. In this embodiment, the inner package 34 functions simply as a pedestal, and its upper surface is left open without being sealed. Here, the crystal vibrating element refers to an element in which a metal film for an excitation electrode and a lead electrode is formed by vapor deposition on a quartz crystal plate. In the assembly of this crystal oscillator, as shown in (b), after the inner package 34 with the crystal vibrating element 41 previously assembled is bonded and fixed on the recess inner step 33,
A metal lid 39 is hermetically fixed to the outer frame upper surface 37 of the package body.

The thus obtained crystal oscillator has a single-sealed structure, so it is low in cost, and the height of the package body 31 can be reduced by the amount that the inner package 34 has no metal cover. . In addition, since only one sealing process is required, the manufacturing process can be simplified, and cost can be reduced by improving productivity. Further, the frequency adjustment work by cleaning, annealing, and metal film deposition for the crystal resonator element 41 mounted on the inner package can be performed at a stage before assembling to the package main body 31. Removal of foreign matter by cleaning, stabilization of aging characteristics by annealing, and adjustment of frequency by deposition of a metal film can be completely completed in advance without causing problems such as adverse effects on the mounted circuit components 36. . And
After assembling the inner package 34 on which the crystal vibrating element subjected to these processes is mounted in the package body, the metal cover 3
Since the sealing is completed by sealing at 9, various characteristics are stabilized, and a piezoelectric oscillator with an extremely high yield can be obtained. FIG. 2 is a cross-sectional view of a crystal oscillator according to another embodiment of the present invention. The feature of this embodiment is that the outer frame 34a of the inner package 34 shown in FIG. The point is that the extra length of the protrusion above the inner package 34 is reduced by the removal. That is, according to the embodiment of FIG.
Although the height of the outer frame of the package main body 31 can be reduced by the amount corresponding to the elimination of the metal lid, the outer frame 34a of the inner package projecting further above the upper surface of the crystal resonator element 41 is an obstacle to further lowering the height. It is clear that Therefore, in the embodiment shown in FIG. 2, the height of the outer frame 34a of the inner package 34 is reduced to be at least equal to or less than the upper surface of the crystal resonator element 41, so that the outer frame height on the package body 31 side is reduced. Reduction was made possible.

[0008]

As described above, in the piezoelectric oscillator according to the present invention, when the crystal resonator element is supported on the inner package supported on the step in the recess of the package body, the inner package is not sealed. After exposing the crystal unit,
In addition to sealing the concave portion of the package body and fixing the inner package on the inner step of the concave portion with the crystal resonator mounted on the inner package in advance, cleaning, annealing, metal It is possible to perform the frequency adjustment operation by vapor deposition in advance, and to stabilize various characteristics of the oscillator as a finished product. Further, by employing a single seal structure, the height of the package body can be reduced by the thickness of the unused metal lid. Furthermore, by reducing the height of the outer frame of the inner package, the height of the package body can be further reduced.

[Brief description of the drawings]

FIGS. 1A and 1B are a longitudinal sectional view and an exploded view of a piezoelectric oscillator according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a piezoelectric oscillator according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a conventional piezoelectric oscillator having a double seal structure.

FIG. 4 is a cross-sectional view showing a configuration of a conventional piezoelectric oscillator having a single seal structure.

[Description of Signs] 31 Package body, 32 Depressed part, 33 Step, 3
4 inner package, 34a outer frame, 35 inner bottom surface, 36
Circuit parts, 37 Outer frame upper surface, 38 Seam ring, 3
9 Metal lid, 40 binder, 41 quartz resonator.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J079 AA04 BA44 HA07 HA28 KA05 5J108 AA02 BB02 CC04 EE03 EE04 EE07 EE18 GG03 GG13 GG15 GG16 HH04 JJ04

Claims (2)

[Claims] 1. A package body having a concave portion on an upper surface, a circuit component mounted on a wiring pattern on an inner bottom surface of the concave portion, and a package component mounted on a step formed at a position higher than the inner bottom surface of the concave portion. A piezoelectric oscillator comprising: a package; a piezoelectric vibrator mounted in a recess on the inner package; and a metal lid fixed to an upper surface of an outer frame of the package body to seal the recess. 2. The piezoelectric oscillator according to claim 1, wherein the height of the outer frame of the inner package is reduced to at least the same height as the upper surface of the crystal resonator.