JP3405330B2 - Piezoelectric oscillator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a piezoelectric oscillator, and more particularly, it has a structure in which a packaged piezoelectric vibrator is fixed on an upper portion of a package part on which electronic parts constituting an oscillation circuit and a temperature compensation circuit are mounted. Regarding improvement of a piezoelectric oscillator.

[0002]

2. Description of the Related Art Due to the rapid price reduction and miniaturization of mobile communication devices such as mobile phones, the price of piezoelectric oscillators such as crystal oscillators used in these communication devices has been reduced. However, there is an increasing demand for miniaturization and thinning. In response to such a demand, not only is the crystal unit packaged, but an oscillation circuit including a frequency adjustment circuit, a frequency temperature compensation circuit, etc. is integrated and integrated into an IC to reduce the number of parts. FIG. 6A is an exploded perspective view showing an external structure of a crystal oscillator as an example of a conventional piezoelectric oscillator, and FIG. 6B is a vertical sectional view thereof. The crystal oscillator 1 has a structure in which a crystal resonator 11 is mounted and integrated on the upper surface (upper surface of the outer frame) of a lower package 2 made of a ceramic laminate.
An outer frame 3 is provided upright along the outer periphery of the lower package 2, and an IC package 6 is fixed on the inner bottom surface of a recess 4 in the outer frame 3 with a binder 5 such as solder. A bonding wire 8 connects between the electrode 6a provided on the upper surface and the bonding pad 7 on the inner bottom surface of the recess. When an electrode is provided on the bottom surface of the IC package, the IC package side electrode and the bonding pad 7 may be connected by ball bonding for flip chip mounting. An external electrode 9 for surface mounting is formed on the outer bottom surface of the lower package 2,
Is connected to a bonding pad 7 or the like by a conductor (not shown). On the upper surface of the outer frame 3, the upper surface electrode 1 electrically connected to the external electrode 9 via the bonding pad 7.
Place 0. Insulating resin is potted in the recessed portion 4 as necessary to fill the insulating resin.
6 may be embedded in the resin. The crystal unit 11 is
The crystal vibrating element 14 is mounted in the recess 13 of the package body 12 made of a ceramic laminated body, and then the recess 13 is formed.
Is hermetically sealed by a metal lid 15. An external electrode 16 is provided on the outer bottom surface of the package body 12, and the external electrode 16 is connected and fixed to the upper surface electrode 10 of the lower package 2 with a binder such as a conductive adhesive. As a result, the recess 4 of the lower electrode 2 is closed by the crystal unit 11. This crystal oscillator 1 is a crystal oscillator 1
It can be realized by integrating all the circuit elements constituting the oscillation circuit and the temperature compensation circuit except 1 in the IC 6 of one chip.

However, in order to manufacture a crystal oscillator by using an expensive IC 6 in which the above-mentioned circuit elements are integrated into one chip, it is premised that the number of mass-produced crystal oscillators 1 themselves can be expected to some extent. However, it is difficult to reduce the cost. Therefore, for example, it is not possible to use this kind of expensive IC6 in an oscillator which is produced in small quantities for a large variety of products because of cost reasons. Therefore, in place of the IC6, there are transistors, resistors, capacitors, etc. constituting the above circuits. It is necessary to mount the circuit element as an individual chip component in the recess 4 of the lower package 2. If the circuit element thus made into a chip component is mounted in the recessed portion 4 of the lower package 2 shown in FIG. 6, a plurality of lands (formed in place of the bonding pad 7 provided on the bottom surface of the recessed portion are formed). It is necessary to mount each chip component on top by the reflow method using cream solder. Normally, the work of applying the cream solder on the land is performed by screen printing using a silk screen (mask), but there is a step formed by the outer frame 3 on the outer periphery of the land forming surface like the lower package 2. In some cases it is not possible to use screen printing techniques. For this reason, it becomes difficult to improve productivity by batch processing that also uses screen printing technique, and there is no choice but to perform the work of applying cream solder by a dispenser for each land, and when using chip parts. Was inevitably high cost. For this reason, when a crystal oscillator is configured using chip parts, the configuration shown in FIG.
As shown in FIG. 2, the chip component 21 and the crystal unit 2 are provided on each land on the wiring substrate 20 having a large area having the land on the upper surface.
There was no choice but to adopt a configuration in which 2 and 2 are mounted by a reflow method. That is, in this type of crystal oscillator, since it is possible to screen-print a land on a flat wiring board 20 having no step, a large area in which a plurality of wiring boards are connected vertically and horizontally is used. Batch processing using the wiring board base material is possible. However, in this crystal oscillator, since all the components 21 and 22 are mounted on the flat wiring board 20, the area occupied when the crystal oscillator is mounted on a printed circuit board (not shown) is inevitably large.
The result is contrary to the demand for high-density mounting of the mounted components on the printed circuit board.

[0004]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to have a structure in which a packaged piezoelectric vibrator is fixed on the upper part of a package part on which electronic parts constituting an oscillation circuit and a temperature compensation circuit are mounted. In the provided piezoelectric oscillator, by adopting a flat board as a wiring board on which electronic components are mounted, it is possible to screen-print cream solder on the land on the wiring board and support mass production by batch processing. The object of the present invention is to provide a piezoelectric oscillator in which a packaged crystal unit is three-dimensionally arranged above a wiring board to reduce the occupied area. Another object is to enable production by batch processing by using a special column member as a means for electrically and mechanically connecting the wiring board and the crystal unit.

[0005]

In order to solve the above-mentioned problems, the invention of claim 1 is a flat wiring board having at least an electronic component constituting an oscillation circuit mounted on its upper surface and having external electrodes on its bottom surface. A piezoelectric oscillator fixed at a predetermined gap via a pillar member fixed to the upper surface of the wiring board, wherein the piezoelectric oscillator is a piezoelectric oscillator in a hermetically sealed space inside a package. The column member has a structure in which a vibrating element is sealed, and an upper portion of the column member is integrated with an outer bottom surface of the package of the piezoelectric vibrator, and a bottom portion of the column member which is electrically connected to an excitation electrode of the piezoelectric vibrating element. An electrode is formed, and a pillar member fixing pattern for fixing the bottom electrode of the pillar member in a conductive state is formed on the upper surface of the wiring board. According to a second aspect of the present invention, there are provided a flat wiring board having a plurality of electronic components constituting an oscillation circuit and a temperature compensation circuit on an upper surface thereof and external electrodes on a bottom surface thereof, and a pillar member fixed to the upper surface of the wiring board. A piezoelectric oscillator having a piezoelectric vibrator fixed via a predetermined gap via the piezoelectric vibrator, wherein the piezoelectric vibrator seals the piezoelectric vibrating element in an airtight space inside the package, and at the same time, the outer bottom surface of the package. A bottom electrode that is electrically connected to the excitation electrode of the piezoelectric vibrating element, the pillar member is a member separate from the wiring board and the piezoelectric vibrator, and the bottom portion of the pillar member is formed on the upper surface of the wiring board. The above-mentioned column member fixing pattern is electrically and mechanically fixed, and the upper part of the column member is electrically and mechanically fixed to the bottom electrode of the piezoelectric vibrator.
A third aspect of the present invention is characterized in that the pillar member includes a ceramic block, and an upper electrode and a bottom electrode that are formed on the upper portion and the lower portion of the ceramic block and are electrically connected to each other. The invention of claim 4 is characterized in that the pillar member is made of a metal block or a metal ball. According to a fifth aspect of the invention, the tallest electronic component among the electronic components is used as the pillar member. The invention of claim 6 is characterized in that the cross-sectional shape of the pillar member is circular, elliptical, or oval.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1A and 1B are a longitudinal sectional view and an exploded perspective view of a crystal oscillator as a piezoelectric oscillator according to an embodiment (first embodiment) of the present invention. This crystal oscillator 31 has a plurality of electronic components 33 constituting an oscillation circuit and a temperature compensating circuit mounted on its upper surface, and a flat plate-shaped wiring board 32 having external electrodes 34 on its bottom surface, and is integrated with the bottom surface of a package 42. The crystal unit 41 is fixed and integrated on the wiring board 32 by fixing a pillar member (leg member) 43 on the upper surface of the wiring board 32 with a predetermined gap. The wiring board 32 is made of, for example, ceramic, and has a land 35 for mounting electronic components on its upper surface and a pillar member fixing pattern 36 for fixing the bottom electrode 44 of the pillar member 43 in a conductive state. The pillar member fixing pattern 36 is electrically connected to each land 35, the external electrode 34, and the like. The crystal unit 41 includes a package 42 including a package body 42a having a recess and a metal lid 42b hermetically sealing the recess, and a crystal vibrating element 45 supported in the recess. Rectangular pillar members 43 are integrated at appropriate places on the bottom surface of the main body 42a, in this example, four corners. A bottom electrode 44 is formed on the bottom surface of the column member 43 so as to be electrically connected to the excitation electrode of the crystal vibrating element 43. The package 42 and the pillar member 43 are made of, for example, ceramic. According to this embodiment, the flat wiring substrate 32
Cream solder is collectively applied on the upper land 35 and the pillar member fixing pattern 36 by screen printing, and the electronic component 33 and the bottom electrode 44 of the pillar member are mounted on each land 35 and the pillar member fixing pattern 36, respectively. After the placement, the electronic components 33 and the crystal oscillator 41 can be fixed on the wiring board 32 by heating in the reflow furnace. A procedure may be adopted in which only the electronic component 33 is reflow-connected onto each land 35, and then the bottom electrode 44 of the pillar member 43 is fixed with a conductive adhesive. In this way, the cream solder can be printed by screen printing on the lands 35 and the like on the wiring board 32, so that batch processing is possible and productivity can be improved. Moreover, since the crystal unit 41 is arranged in parallel with the upper surface of the wiring substrate 32 with a predetermined gap, the plane area of the crystal oscillator 31 can be reduced.
Also, by setting the bottom area of the pillar member 43 to be as narrow as possible, it is possible to increase the effective area available for mounting electronic components in the area of the upper surface of the wiring board 32.

Next, a second embodiment of the present invention will be described with reference to FIGS. The piezoelectric oscillator (crystal oscillator) of the second embodiment is different from that of the first embodiment in that the pillar member is formed as a member separate from the crystal resonator package. That is, in the second embodiment, a plurality of electronic components 33 forming an oscillation circuit and a temperature compensation circuit are mounted on a land 35 on the upper surface, and a flat wiring substrate 32 having an external electrode 34 on the bottom surface, In the piezoelectric oscillator including the piezoelectric vibrator 41 fixed to the upper surface of the wiring board 32 via the pillar member 50 with a predetermined gap therebetween, the pillar member 50 is different from the wiring board 32 and the piezoelectric vibrator 41. As a separate member, the bottom of the pillar member 50 is further connected to the wiring board 3
It is characterized in that it is electrically and mechanically fixed to a pillar member fixing pattern 36 formed on the upper surface of 2, and the upper portion of the pillar member 50 is electrically and mechanically fixed to the bottom electrode of the piezoelectric vibrator. First, in the embodiment shown in FIG. 2, the flat ceramic wiring board 3 is used.
The crystal resonator 41 is mounted on the pillar member fixing pattern 36 on the upper part 2 via the pillar member 50. Wiring board 3
2 is an electronic component 33 on the land 35 formed on the upper surface thereof.
And has external electrodes 34 that are electrically connected to the respective lands 35 on the bottom surface. Further, a column member fixing pattern 36 is provided at a proper position on the upper surface. The configuration of the piezoelectric vibrator 41 is the same as that of the embodiment shown in FIG. 1 except that the bottom electrode 46 is provided instead of fixing the column member on the bottom surface of the package body 42a. The pillar member 50 according to this embodiment is a quadrangular prism or other polygonal pillar-shaped ceramic block 51 (thickness of about 0.3 to 0.5 mm) and a bottom electrode (metallized portion) 52 provided at the bottom of the ceramic block 51. And an upper electrode (metallized portion) 53 provided on the upper portion of the ceramic block 51, and a connection conductor 54 that electrically connects the electrodes 52, 53.

The pillar member 50 of this embodiment is the wiring board 3
2 and the crystal oscillator 41 are separate structures, so when the pillar member 50 is fixed on the pillar member fixing pattern 36 on the wiring board 32, the pillar member fixing pattern 36 is formed by screen printing. Reflow connection using the cream solder applied on top is possible. That is, in this screen printing, the application of cream solder to the land 35 is also performed at the same time, and the electronic component 33 and the pillar member 50 are placed on the land 35 and the pillar member fixing pattern 36 to which the cream solder is applied, respectively. Then, the electronic component 33 and the pillar member 50 are fixed by simultaneously heating in the reflow furnace and then cooling. Regarding the crystal unit 41, after fixing the pillar member 50 on the wiring board 32,
The bottom electrode 46 may be fixed on the top electrode 53 of the pillar member 50 using a conductive adhesive or the like, or the top electrode 53 and the bottom electrode 46 may be connected by reflow connection of the electronic component 33 or the like. You may implement simultaneously. According to this embodiment,
Since the pillar member 50 is configured as a member different from the wiring board 32 and the crystal oscillator 41, it is possible to mount and fix the electronic component 33 and the pillar member 50 on the wiring board 32 by batch processing. Becomes That is, after the cream solder is applied by screen printing to each of the land group and the pillar member fixing pattern group formed on the wiring board base material having a large area, each land 35 and the pillar member fixing pattern 36 are applied. The electronic component 33 and the pillar member 50 are provided on the top, respectively.
The connection can be completed by placing the bottom electrode 52 of No. 1 and then heating them together in the reflow furnace.
Therefore, the productivity of the crystal oscillator can be improved.

Next, in another example of the second embodiment of the present invention, instead of the ceramic block 51 as the pillar member 50, a square pillar or polygonal pillar-shaped metal having a thickness of about 0.3 to 0.5 mm is used. Use blocks. That is, a metal block made of a conductive metal material is used in place of the ceramic block 51, and the pillar member fixing pattern 36 and the bottom electrode 46 of the crystal unit are connected by soldering or the like. A configuration similar to that of the crystal oscillator of No. 2 can be realized. By using the conductive metal block as the pillar member 50, it is not necessary to provide the electrodes 52, 53 and the connection conductor 54, unlike the case of the ceramic block. Alternatively, instead of the metal block, a metal ball having a diameter of about 0.3 to 0.5 mm may be used as the pillar member 50. That is, FIG. 3 shows a pillar member fixing pattern 36 on the wiring board 32 using a pillar member 50 made of a metal ball.
An example in which the bottom electrode 46 on the bottom surface of the crystal unit is connected is shown. The connection between the pillar member 50 and the pillar member fixing pattern 36 and the connection method between the pillar member 50 and the bottom electrode 46 may be reflow connection using cream solder, respectively, or a conductive adhesive may be used. It may be the connection used. Also in this case, as in the case of using the metal block, the electrodes 52,
The labor for providing 53 and the connecting conductor 54 becomes unnecessary.

Next, FIG. 4 is a diagram showing another example of the crystal oscillator according to the second embodiment of the present invention. The same parts as those of the embodiment shown in FIG. To do. This embodiment differs from the crystal oscillator of the embodiment of FIG. 2 in that
As the pillar member 50, the tallest electronic component 33A of the chip type electronic components 33 is used. In the illustrated example, a plurality of tallest electronic components 33A are arranged by using a binder such as solder on the pillar member fixing pattern 36 that also serves as a land provided on the upper edge of the wiring board 32, and each electronic component 33A is arranged. The package bottom surface of the crystal unit 41 is fixed to the upper surface of 33A. The upper surface of the electronic component 33A is electrically connected to the bottom electrode 46 of the crystal oscillator 41, so that the crystal vibrating element 45 inside the crystal oscillator and each electronic component 33,
It is configured to ensure electrical continuity with 33A. It is important that the plurality of electronic components 33A used as the pillar members have the same height, but the arrangement position on the wiring board 32 is not limited to the illustrated position. According to this embodiment, an electronic component 33A that is taller than the electronic components 33 that should originally be mounted on the wiring board 32 without preparing a special pillar member.
Since a plurality of columns are selected and used as the pillar member, the cost of parts and the number of manufacturing steps can be reduced.

Next, FIGS. 5A and 5B are partial configuration diagrams showing an example of a crystal oscillator according to a third embodiment of the present invention.
In this embodiment, the pillar members 43, 50 to be used have a planar shape (bottom surface shape or transverse cross-sectional shape) of a circle or an ellipse shape (including an oval shape).
When the wiring board 32 and the crystal unit 41 are bonded via the interposition, even if the pillar members 43 and 50 are misaligned in the rotation direction, the pillar members 43 and 50 move outward from the edge of the wiring board 32. The feature is that it does not project.
That is, as shown in FIG. 5C, when the pillar members 43 and 50 have a rectangular planar shape or another polygonal shape, the pillar member 4
When 3 and 50 deviate in the rotation direction from the original mounting position indicated by the dotted line for some reason, their corners are fixed in a state of protruding outward from the edge of the wiring board 32, and this becomes a burr. And cause a malfunction. However, as shown in FIGS. 5 (a) and 5 (b), the pillar members 43 and 50 are rotated to some extent by making the planar shape of the pillar members 43 and 50 into a shape having no corners such as a circular shape or an elliptical shape. Even if
It does not easily project outward from the edge of the wiring board, and even if the peripheral surface of the column member slightly projects, the corners do not project, so that no burr is generated and no problem occurs.

[0012]

As described above, according to the present invention, the piezoelectric oscillator having the structure in which the packaged piezoelectric vibrator is fixed on the upper part of the package part on which the electronic parts constituting the oscillation circuit and the temperature compensation circuit are mounted. In this case, by adopting a flat board as a wiring board on which electronic parts are mounted, it is possible to screen-print cream solder on the land on the wiring board and package it while supporting mass production by batch processing. It is possible to provide a piezoelectric oscillator in which the occupied area is reduced by arranging the crystal oscillator in three dimensions above the wiring board. Further, by using a special column member as a means for electrically and mechanically connecting the wiring board and the crystal unit, it is possible to carry out manufacturing by batch processing. That is, in the invention of claim 1, the pillar member is previously integrated with the bottom of the piezoelectric vibrator, and the pillar member is electrically and mechanically connected to the pillar member fixing pattern on the wiring board. It is possible to construct a piezoelectric oscillator having a small occupied area while using a flat wiring board. Therefore, the wiring boards can be mass-produced by batch processing, and the planar shape of the oscillator can be reduced. According to a second aspect of the present invention, the pillar member is a member separate from the wiring board and the piezoelectric vibrator, and a bottom portion of the pillar member is electrically connected to a pillar member fixing pattern formed on an upper surface of the wiring board. Mechanically and mechanically, and the upper part of the pillar member is electrically and mechanically fixed to the bottom electrode of the piezoelectric vibrator. Therefore, the electronic parts and The step of mounting the pillar member can be carried out, and the mass productivity can be improved. According to the invention of claim 3, since the pillar member includes the ceramic block and the upper electrode and the bottom electrode which are respectively formed on the upper portion and the lower portion of the ceramic block and are electrically connected to each other, the pillar cost is reduced. It becomes possible to mass-produce the members and use them. The invention of claim 4 is
Since the metal block or the metal ball is used as the pillar member, the structure of the pillar member can be further simplified and the productivity can be improved. In the invention of claim 5, since the tallest electronic component among the electronic components is used as the pillar member,
It is possible to reduce the number of parts and manufacture without preparing a special pillar member. In the invention of claim 6, since the pillar member has a bottom surface shape of a circle, an ellipse, or an oval, even if the pillar member is rotated for some reason, a part of the pillar member is an end of the wiring board. No more burrs protruding from the edges.

[Brief description of drawings]

1A and 1B are a longitudinal sectional view and an exploded perspective view of a crystal oscillator as a piezoelectric oscillator according to an embodiment (first embodiment) of the present invention.

FIG. 2 is a structural explanatory view of a crystal oscillator as an example of a piezoelectric oscillator according to a second embodiment of the present invention.

FIG. 3 is a configuration explanatory diagram of a crystal oscillator as another example of the piezoelectric oscillator according to the second embodiment of the invention.

FIG. 4 is a configuration explanatory view of a crystal oscillator as another example of the piezoelectric oscillator according to the second embodiment of the invention.

5A to 5C are configuration explanatory views of a crystal oscillator as another example of the piezoelectric oscillator according to the second embodiment of the invention.

6A and 6B are explanatory views of a conventional example.

FIG. 7 is an explanatory diagram of another conventional example.

[Explanation of symbols]

31 crystal oscillator, 32 wiring board, 33, 33A electronic part, 34 external electrode, 35 land, 36 pillar member fixing pattern, 41 crystal resonator, 42 package, 42a package body, 42b metal lid, 43
Column member, 44 Bottom electrode, 50 Column member, 51 Ceramic block, 52 Bottom electrode (metallized part), 53
Upper electrode (metallized portion), 54 connection conductor.

Continuation of the front page (56) References JP 2000-134037 (JP, A) JP 2000-13141 (JP, A) JP 2000-299611 (JP, A) JP 2000-298047 (JP, A) Special Kai 59-91719 (JP, A) JP 8-264918 (JP, A) JP 2000-151283 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H03B 5 / 30-5/36 H03H 9/00-9/24

Claims (6)

(57) [Claims] 1. A flat wiring board having at least electronic components constituting an oscillation circuit mounted on the top surface and external electrodes on the bottom surface, and a column member fixed to the top surface of the wiring board, with a predetermined gap therebetween. And a piezoelectric oscillator fixed, wherein the piezoelectric oscillator has a configuration in which a piezoelectric vibrating element is sealed in an airtight space in a package, and the pillar member has an upper portion thereof, A bottom electrode integrated with the outer bottom surface of the package of the piezoelectric vibrator is formed on the bottom of the pillar member, the bottom electrode being electrically connected to the excitation electrode of the piezoelectric vibrating element, and the bottom electrode of the pillar member on the upper surface of the wiring board. A piezoelectric oscillator, wherein a column member fixing pattern for fixing in a conductive state is formed. 2. A flat wiring board having a plurality of electronic parts constituting an oscillation circuit and a temperature compensation circuit mounted on the top surface and external electrodes on the bottom surface, and a pillar member fixed to the top surface of the wiring board. A piezoelectric oscillator comprising a piezoelectric vibrator fixed at a predetermined gap, wherein the piezoelectric vibrator seals the piezoelectric vibration element in an airtight space inside the package, and the piezoelectric vibrator is formed on the outer bottom surface of the package. A bottom electrode is provided which is electrically connected to the excitation electrode of the piezoelectric vibrating element, and the pillar member is a member separate from the wiring board and the piezoelectric vibrator, and the bottom portion of the pillar member is formed on the top surface of the wiring board. A piezoelectric oscillator characterized by being electrically and mechanically fixed to a member fixing pattern, and at the same time being electrically and mechanically fixed to an upper surface of the pillar member with a bottom electrode of the piezoelectric vibrator. 3. The pillar member includes a ceramic block,
3. The piezoelectric oscillator according to claim 2, further comprising: an upper electrode and a bottom electrode which are formed on the top and bottom of the ceramic block and are electrically connected to each other. 4. The piezoelectric oscillator according to claim 2, wherein the pillar member is made of a metal block or a metal ball. 5. The piezoelectric oscillator according to claim 2, wherein the tallest electronic component among the electronic components is used as the pillar member. 6. The pillar member has a circular cross-sectional shape,
3. An elliptical shape or an oval shape.
The piezoelectric oscillator according to 3, 4, or 5.