JPH11355045A - Structure of piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin the whole height in a state where an oscillator is mounted on a printed board by thinning the piezoelectric oscillator incorporated with the piezoelectric oscillator of sealing structure. SOLUTION: In this structure 1 of the piezoelectric oscillator, a piezoelectric oscillator 3 and an oscillation circuit are mounted on a printed board 2 and they are covered by a metallic case 5. An opening is formed on the upper face of the metallic case, which is equivalent to the upper face of the piezoelectric oscillator, and at least a part of the upper face of the piezoelectric oscillator is engaged into the opening and therefore the height of the metallic case is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a piezoelectric oscillator which can reduce the height when mounted on a printed wiring board and can respond to a demand for thinning.

[0002]

2. Description of the Related Art Piezoelectric devices such as a vibrator using a piezoelectric element represented by a quartz crystal include a piezoelectric oscillator, a resonator,
Or, it is used as an indispensable main part in various electronic devices, especially in communication devices, as a filter.
In recent years, in order to cope with electronic devices that are becoming smaller and thinner as seen in mobile phones, ultra-small piezoelectric devices are also expected. 8A is a longitudinal sectional view of an example of a conventional piezoelectric oscillator, FIG. 8B is a longitudinal sectional view of a piezoelectric vibrator accommodated in the piezoelectric oscillator, FIG. 8C is a bottom view of FIG.
FIG. 3 is a diagram illustrating an example of a circuit of a piezoelectric oscillator. As shown in FIG. 1A, a piezoelectric oscillator 100 includes a printed circuit board 101 on which a packaged piezoelectric vibrator 102 and a circuit component 103 constituting an oscillation circuit are mounted adjacent to each other. It has a configuration in which the top is covered by a conductive case 104 that is grounded. The reason why the structure covered by the grounded case that covers the entire components on the substrate is adopted is to increase the frequency stability and to improve the EMI characteristics. That is, the piezoelectric vibrator 102 includes a crystal vibrating element 105 and a package 106 for sealing the crystal vibrating element 105 as shown in FIG. Are connected to external terminals H, H exposed on the bottom surface of the package as shown in FIG. 8C by conductors 106a penetrating through the package 106, respectively. Projection 107 provided on inner bottom surface of package 106
A quartz vibrating element 105 is mounted thereon, and is connected to a pad on the protrusion 107 by a conductive adhesive 108 or the like. G is a package terminal or a ground terminal connected to a ground pattern.

[0003]

However, in a situation where electronic devices are becoming smaller and, in particular, thinner, the demand for thinner piezoelectric oscillators, which are relatively large components, is particularly strong. In the electrode structure of the package shown in FIG. For example, there has been proposed a piezoelectric oscillator as shown in FIG. 8A, in which the upper surface of a case (top surface of a lid) of a piezoelectric vibrator 102 and the ceiling surface of a case 104 are brought into close contact with each other and spot-welded to each other. In a piezoelectric oscillator having a built-in piezoelectric vibrator having a sealing structure, there has been a limit in reducing the thickness of the piezoelectric oscillator. Further, the upper surface of the case of the piezoelectric vibrator and the case
In the case of spot welding with the ceiling surface of No. 4, fine dust is scattered from the welding portion of the ceiling surface of the case 104 due to welding with a large current, and adheres to a circuit or the like on the printed circuit board 101 to cause a short circuit or the like. Not only does this cause a problem, but also fine dust scatters from the welding location on the ceiling of the case of the piezoelectric vibrator 102 and adheres to the electrode film of the quartz vibrating element 105 in the case, causing a change in frequency. In addition, expensive equipment is required to perform spot welding, and there is a problem that the process is complicated due to the complicated management and setting of conditions. Further, if the case of the piezoelectric vibrator and the case 104 are once welded by spot welding, it becomes difficult to open the case. Therefore, it is difficult to open the case 104 after welding to find a defect or to perform readjustment. Become. Further, once welded, the labeling display formed on the upper surface of the case 104 suffers from display damage, making it impossible to visually confirm the labeling display, or impairing the beauty. In order to solve these problems, means for fixing the upper surface of the crystal unit to the metal case 104 with solder or a conductive adhesive can be considered, but the demand for thinning cannot be satisfied. . The problem to be solved by the present invention is to achieve a thinner piezoelectric oscillator having a built-in piezoelectric vibrator having a sealed structure, thereby realizing a thinner overall height when mounted on a printed circuit board. It is an object of the present invention to provide a structure of a piezoelectric oscillator that can realize the above.

[0004]

According to one aspect of the present invention, there is provided a piezoelectric oscillator having a structure in which a piezoelectric vibrator and an oscillation circuit are mounted on a printed circuit board and covered with a metal case. An opening is formed in the upper surface of the metal case corresponding to the upper surface of the piezoelectric vibrator, and the height of the metal case is reduced by fitting at least a part of the upper surface of the piezoelectric vibrator into the opening. I do. The invention according to claim 2 is such that a stepped lid located on the upper surface of the piezoelectric vibrator is fitted into the metal case opening, and the ground pattern provided on the lower surface of the upper surface of the piezoelectric vibrator and the metal case ceiling surface are connected to each other. It is characterized by being fixed. The invention according to claim 3 is characterized in that solder or a conductive adhesive is used as means for fixing the ground pattern provided at a low position on the upper surface of the piezoelectric vibrator and the ceiling surface of the metal case. The invention according to claim 4 is based on claim 1,
2 or 3, wherein the height is reduced by embedding a piezoelectric vibrator in a recess formed on the upper surface of the printed circuit board.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. 1 (a), 1 (b) and 1 (c) are a front vertical sectional view, a plan view with a case removed, and a right side view of a piezoelectric oscillator according to an embodiment of the present invention. A quartz oscillator (piezoelectric oscillator) 3 having a sealing structure and a circuit component 4 constituting an oscillation circuit are arranged adjacent to each other on a printed board 2, and the upper surface of the printed board is placed in a metal case
By fitting (exposing) at least a part of the upper surface of the piezoelectric oscillator 1 into the opening 6 provided in the metal case 5, the piezoelectric vibrator is provided in the opening 6 of the metal case 5 of the oscillator. The feature is that the height of the metal case 5 is reduced by the amount of the fitting of the upper part of the child 3, thereby reducing the overall height of the piezoelectric oscillator itself. In order to reduce the overall height of the piezoelectric oscillator, in the present embodiment, it is possible to reduce the overall height by reducing the height of the metal case 5 of the oscillator without making a particularly large modification to the quartz oscillator or the like.

Hereinafter, the structure of a piezoelectric oscillator according to an embodiment of the present invention will be described. 2 (a), 2 (b), 2 (c) and 2 (d) are front views of an example of a piezoelectric vibrator used in the oscillator of the present invention.
FIG. 4 is a plan view, a left side view, and a bottom view. The quartz oscillator 3 serving as a piezoelectric oscillator supports a quartz oscillator (not shown) in a recess formed on the upper surface of a package body 10 made of ceramic or the like. The excitation electrode on the quartz vibrating element is electrically and mechanically connected and fixed to the pad exposed on the inner bottom surface of the package body, and the electrode 11 electrically connected to the pad is exposed on the outer bottom surface or outer wall of the package. It has a configuration in which a concave portion of the main body is covered with a metal lid 12. Note that, in this example, the metal lid 12 is configured to be located on the inner side of the outer contour of the outer frame upper surface 10a of the package body 10. Next, as shown in FIG. 1, in the present embodiment, a wiring pattern 15 in which the quartz oscillator 3 as shown in FIG.
It is mounted on and fixed by soldering or the like, and the upper surface of the substrate including the crystal unit 3 and the circuit component group 4 forming the oscillation circuit is covered by the metal case 5. A characteristic configuration of the present embodiment is that an opening 6 is formed at an appropriate position on the upper surface of the case 5, for example, at a portion corresponding to the upper surface of the piezoelectric vibrator 3. It is in the point that they are fitted only. That is, the height of the metal case 5 is reduced by an amount corresponding to the upper portion of the piezoelectric vibrator 3 fitted into the opening 6, thereby reducing the overall height of the oscillator.

When the piezoelectric vibrator 3 shown in FIG. 2 is applied to this oscillator structure, for example, a lid 12 protruding from the upper surface 10a of the outer frame of the piezoelectric vibrator is fitted into the opening 6 to fit therein. The size and shape of the opening 6 are set so that the upper surface of the lid 12 is exposed from the opening 6. In this embodiment, the opening area is such that not only the lid 12 but also the outer frame upper surface 10a (lower surface of the piezoelectric vibrator) located outside the lid 12 is exposed. Depending on the amount of projection (thickness) of the lid 12 projecting from the outer frame upper surface 10 a and the thickness of the metal case 5, the upper surface of the lid 12 may protrude above the opening 6, or may fall within the opening 6. In any case, the height of the metal case 5 can be reduced, and the height of the entire piezoelectric oscillator can be reduced. In this embodiment, as a method of fixing the metal case 5, for example, the connection piece 2 provided on the side wall of the metal case 5 is connected to the ground pattern 20 formed in the recess 2 a on the side surface of the printed circuit board 2.
1 is fixed to the outer frame upper surface 10a of the package 10 by metallization, and the metal pattern opposing the outer frame upper surface 10a The ceiling of the case 5 is connected to the metal case 5 by soldering or conductive adhesive.
And the like can be implemented. In the latter case, it is needless to say that the inner peripheral edge of the opening 6 needs to be overhanged on the outer frame upper surface 10a. Also,
When connecting the outer frame upper surface 10a and the ceiling surface of the metal case 5, the connection using the ground pattern 20 on the side surface of the printed circuit board can be omitted.

Next, FIGS. 3 (a), 3 (b) and 3 (c) are front vertical sectional views (sectional views taken along line AA of FIG. 3 (b)), plan views, and FIGS. FIG.
Is a crystal oscillator (piezoelectric oscillator) 3 having a sealing structure on a printed circuit board 2 and an oscillation circuit IC having an equivalent height.
The circuit component 4 including the circuit board 30 is disposed adjacently, and the upper surface of the printed circuit board is covered by the metal case 5. At least a part of the upper surface of the piezoelectric oscillator 1 and the oscillation circuit IC 30 is provided in the metal case 5. 6 is fitted (exposed) into the opening 6 of the metal case 5 of the oscillator.
The feature is that the height of the metal case 5 is reduced by an amount corresponding to the fitting of the piezoelectric vibrator 3 and the upper part of the IC 30 therein, thereby reducing the overall height of the piezoelectric oscillator itself. In order to reduce the overall height of the piezoelectric oscillator, in the present embodiment, it is possible to reduce the overall height by reducing the height of the metal case 5 of the oscillator without making particularly large modifications to the crystal oscillator, the IC, and the like. . As the crystal resonator 3 used in the piezoelectric oscillator 1 of this embodiment, for example, the one having the configuration shown in FIG. 2 is used. The oscillation circuit IC 30 has a package 30 a having substantially the same height as the piezoelectric oscillator 1, and has a height such that the upper end thereof fits into the opening 6 formed on the flat upper surface of the metal case 5. It has. The opening 6 formed on the upper surface of the metal case 5 of this embodiment is the first opening for fitting the lid 12 on the upper surface of the crystal unit 3.
6A and a second opening 6B into which the upper part of the oscillation circuit IC 30 is fitted. The first opening 6A has a large opening area where the outer frame upper surface 10a of the package 10 is exposed, and the second opening 6B has an opening area where the package 30a and a part of the lead terminal 30a of the IC 30 are exposed. . In the piezoelectric oscillator of this embodiment, as a method of fixing the metal case 5, for example, a connection piece 21 provided on the side surface of the metal case 5 with respect to the ground pattern 20 formed in the recess 2 a on the side surface of the printed board 2 is used. A method of connecting and fixing with solder, conductive adhesive or the like is used.

Next, FIGS. 4 (a), 4 (b) and 4 (c) are a front vertical sectional view, a plan view and a right side view of a modification of the embodiment of FIG. 3 of the present invention. The piezoelectric oscillator has a metal case 5
Of the openings 6 '(6A', 6B ') formed on the upper surface of
The opening area of the first opening 6A ′ into which the piezoelectric vibrator 3 is fitted is made smaller than that of the first opening 6A in the embodiment of FIG.
The outer frame upper surface 10a of the package 10 of the crystal unit is not exposed. Further, the ground pattern 2 is formed on the outer frame upper surface (lower part of the piezoelectric vibrator upper surface) 10a by metallizing.
2, and the ceiling surface (the lower surface of the peripheral edge of the first opening 6A) of the metal case 5 overhanging on the ground pattern 22 is joined and integrated with solder or a conductive adhesive. That is, as a method of fixing the metal case 5,
Ground pattern 22 on outer frame upper surface 10a of package 10
The metal case 5 is fixed to the metal case 5 at the same time as the metal case is fixed.

In this embodiment, the recess 2a on the side of the printed circuit board and the connection piece 21 on the side of the case simply function as means for positioning the printed circuit board and the case. In other words, it is not necessary to ground the case at the recess. Alternatively, when an earth pattern is formed in the recess 2a and the earth pattern is connected to the connection piece 21, it is not always necessary to provide an earth pattern on the upper surface of the outer frame of the package and join it to the case ceiling surface. . The positioning of the metal case 5 and the printed circuit board 2 is performed by the claw 5a provided on the lower end edge of the other side wall of the metal case 5, and the ground pattern 22 and the ceiling surface of the metal case 5 are joined together. 2a and the connecting piece 21 can be eliminated, and the shapes of the printed circuit board 2 and the metal case 5 can be simplified to reduce the number of processing steps. In the above embodiment, the piezoelectric vibrator housed in the piezoelectric oscillator has been described as a crystal vibrator, but this is merely an example, and it goes without saying that any type of piezoelectric vibrator can be used.

Next, FIGS. 5 (a), 5 (b) and 5 (c) are a front vertical sectional view, a main part plan view and a side view of a piezoelectric oscillator according to another embodiment of the present invention. The configuration in which the quartz oscillator 3 is embedded in a recess 40 formed at an appropriate position on the upper surface of the printed circuit board 2 is different from the embodiment of FIG. By embedding the crystal oscillator 3 in the recess 40, the height of the projection of the crystal oscillator on the printed circuit board 2 is reduced, and by exposing the metal lid 12 from the opening 6 provided in the metal case, the entire oscillator is formed. The height is being reduced. Circuit components mounted on the printed circuit board 2 (ICs, oscillation circuit components, etc.)
As for No. 4, the height can be reduced by using a chip component. In this embodiment, FIGS. 6 (a) to 6 (d)
Is used. This crystal oscillator 3 is different from the one shown in FIG. 2 in that the electrodes 11 are not arranged on the bottom surface of the package main body 10 but the electrodes 11 are arranged on the ceiling surface of the recesses 41 provided at the four corners of the package main body bottom surface. It is in the point provided. Each electrode 11 is connected to each wiring pattern 15 formed on the upper surface of the printed circuit board 2 in one-to-one correspondence. Assuming that the wiring pattern 1 is
5, the conductor for connecting this wiring pattern to the wiring pattern on the printed circuit board 2 needs to be wired inside the thickness of the printed circuit board, which complicates the printed circuit board structure and the manufacturing process. In the example, the configuration is such that the wiring pattern 15 formed on the upper surface of the printed board 2 is connected to the electrode 11 in the recess 41, so that the configuration of the printed board is not likely to be complicated. Therefore, as shown in the perspective view of FIG. 7, the recess 40 has a shape capable of receiving the lower portion of the package body 10 other than the recess 41. In addition,
The configuration for reducing the height shown in FIGS. 5, 6, and 7 is the same as that shown in FIG.
The present invention can be applied not only to the embodiment shown in FIG.

[0012]

As described above, according to the piezoelectric oscillator of the present invention, the structure of the piezoelectric oscillator in which the piezoelectric vibrator accommodating the piezoelectric vibrating element and the amplifier circuit are mounted on a printed circuit board and covered with a metal case. In the above, since the upper surfaces of the components such as the piezoelectric vibrator and the amplifier circuit are partially fitted into the opening formed in the metal case having a reduced height, the height of the piezoelectric oscillator can be reduced, and therefore the piezoelectric oscillator can be reduced. When mounted on a printed circuit board of an electronic device, the overall height and thickness can be reduced. In addition, the step-shaped lid located on the upper surface of the piezoelectric vibrator was fitted into the metal case opening, and the ground pattern provided at the lower part of the upper surface of the piezoelectric vibrator and the metal case ceiling were fixed. The connection between the child and the metal case and the grounding operation can be completed in one operation, and the number of manufacturing steps can be reduced.

[Brief description of the drawings]

1 (a), (b) and (c) are front longitudinal sectional views of a piezoelectric oscillator according to one embodiment of the present invention, plan views with a case removed,
And a right side view.

FIGS. 2 (a), (b), (c) and (d) are a front view, a plan view, a left side view, and a bottom view of an example of a piezoelectric vibrator used in the oscillator of the present invention.

3 (a), (b) and (c) are a front vertical cross-sectional view (cross-sectional view taken along line AA of (b)), a plan view, and a side view of a piezoelectric oscillator according to another embodiment of the present invention.

4 (a), (b) and (c) are a front vertical sectional view, a plan view, and a right side view of a modification of the embodiment shown in FIG. 3 of the present invention.

5 (a), (b) and (c) are a front vertical sectional view, a plan view with a case removed, and a right side view of a piezoelectric oscillator according to another embodiment of the present invention.

6 (a), (b), (c) and (d) are a front view, a plan view, a left side view, and a bottom view of an example of the piezoelectric vibrator used for the oscillator of FIG.

7 is a perspective view of the piezoelectric vibrator of FIG. 6 and a recess on the printed circuit board side.

FIG. 8A is a longitudinal sectional view of an example of a conventional piezoelectric oscillator,
(b) is a longitudinal sectional view of a piezoelectric vibrator accommodated in the piezoelectric oscillator, (c) is a bottom view of (b), and (d) is a diagram showing an example of an equivalent circuit of the piezoelectric oscillator.

[Explanation of symbols]

1 piezoelectric oscillator, 2 printed circuit board, 2a recess, 3
Crystal oscillator (piezoelectric oscillator), 4 oscillation circuit parts, 5 metal case, 6, 6 ', 6A, 6B, 6A', 6B 'opening, 10 package body, 10a outer frame upper surface, 11
Electrode, 12 metal lid, 15 wiring pattern, 20 ground pattern, 22 ground pattern, 30 IC for oscillation circuit.

Claims (4)

[Claims] In a structure of a piezoelectric oscillator in which a piezoelectric vibrator and an oscillation circuit are mounted on a printed circuit board and covered with a metal case, an opening is formed in an upper surface of the metal case corresponding to an upper surface of the piezoelectric vibrator. The height of the metal case is reduced by fitting at least a part of the upper surface of the piezoelectric vibrator into the opening, thereby reducing the height of the metal case. 2. A step-shaped lid located on the upper surface of the piezoelectric vibrator is fitted into the metal case opening, and a ground pattern provided at a lower position on the upper surface of the piezoelectric vibrator and a metal case ceiling surface are fixed. The structure of the piezoelectric oscillator according to claim 1, wherein: 3. The method according to claim 1, wherein a solder or a conductive adhesive is used as a means for fixing a ground pattern provided at a low position on the upper surface of the piezoelectric vibrator and a ceiling surface of the metal case. Structure of the piezoelectric oscillator. 4. The structure of a piezoelectric oscillator according to claim 1, wherein the height is reduced by embedding a piezoelectric vibrator in a recess formed on the upper surface of the printed circuit board.