JP2002064333A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator which attains reduction of an occupied area by three-dimensionally locating a packaged crystal vibrator above a wiring board while dealing with mass-production based on batch processing by enabling screen printing of cream solder on a land on the wiring board by adopting a plate-like substrate as a wiring board to package electronic components, concerning a piezoelectric oscillator provided with a configuration fixing the packaged piezoelectric vibrator at the upper part of a package part to package the electronic components constituting an oscillation circuit or temperature compensating circuit. SOLUTION: While using pillar members 43 integrated on the bottom of a piezoelectric vibrator 41 or pillar members 50 as separate bodies, these pillar members 43 and 50 are electrically and mechanically connected to patterns 36 for pillar member fixing on a wiring board 32.

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, to a piezoelectric oscillator having a structure in which a packaged piezoelectric vibrator is fixed above a package portion on which electronic components constituting an oscillation circuit and a temperature compensation circuit are mounted. It relates to improvement of a piezoelectric oscillator.

[0002]

2. Description of the Related Art With the rapid spread of cost reduction and miniaturization accompanying the spread of mobile communication devices such as mobile phones, the price of piezoelectric oscillators such as crystal oscillators used in these communication devices has also been reduced. There is an increasing demand for miniaturization and thinning. In response to such demands, not only are crystal oscillators packaged, but also oscillation circuits including frequency adjustment circuits and frequency temperature compensation circuits are integrated and integrated into ICs to reduce the number of components. 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 longitudinal sectional view thereof. The crystal oscillator 1 has a configuration in which a crystal resonator 11 is mounted on an upper surface (upper surface of an outer frame) of a lower package 2 made of a ceramic laminate and integrated.
The lower package 2 has an outer frame 3 erected along its outer periphery, and an IC package 6 is fixed on the inner bottom surface of the recess 4 in the outer frame 3 by a binder 5 such as solder. The 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 and flip-chip mounted. External electrodes 9 for surface mounting are formed on the outer bottom surface of the lower package 2.
Are electrically connected to the bonding pad 7 and the like by a conductor (not shown). On the upper surface of the outer frame 3, the upper electrode 1 electrically connected to the external electrode 9 via the bonding pad 7
0 is placed. It is to be noted that an insulating resin is potted in the recess 4 as needed to fill the recess, thereby providing an IC.
6 may be embedded in the resin. The crystal unit 11
After mounting the crystal resonator element 14 in the recess 13 of the package body 12 made of the ceramic laminate, the recess 13
Is hermetically sealed by a metal cover 15. External electrodes 16 are provided on the outer bottom surface of the package body 12, and the external electrodes 16 are connected and fixed to the upper surface electrodes 10 of the lower package 2 by a binder such as a conductive adhesive. As a result, the concave portion 4 of the lower electrode 2 is closed by the crystal oscillator 11. This crystal oscillator 1 includes a crystal oscillator 1
This is realized by integrating all the circuit elements constituting the oscillation circuit and the temperature compensating circuit except for 1 into an IC 6 of one chip.

However, in order to manufacture a crystal oscillator using an expensive IC 6 in which the above-described circuit elements are formed into one-chip ICs, it is necessary to expect a certain number of crystal oscillators 1 in mass production. It is difficult to reduce the cost. Therefore, for example, it is not possible to use such an expensive IC 6 in an oscillator that is produced in a large variety and in small quantities for reasons of cost. It is necessary to mount the circuit elements as individual chip components in the recess 4 of the lower package 2. If the circuit element formed as a chip component is mounted in the concave portion 4 of the lower package 2 shown in FIG. 6, a plurality of lands (formed in place of the bonding pads 7) provided on the bottom surface of the concave portion are provided. It is necessary to mount each chip component by a reflow method using cream solder. Normally, the work of applying cream solder on the land is performed by screen printing using a silk screen (mask). However, there is a step formed of the outer frame 3 on the outer periphery of the land forming surface as in the lower package 2. In some cases, it is not possible to use screen printing techniques. For this reason, it becomes difficult to increase the productivity by batch processing using the screen printing technique in combination, and it is necessary to carry out the work of applying cream solder by a dispenser for each land, and when chip components are used. Also had to be expensive. Therefore, when a crystal oscillator is configured using chip components, FIG.
As shown in FIG. 2, a chip component 21 and a crystal oscillator 2 are provided on each land on a large-area wiring board 20 having a land on an upper surface.
2 has to be adopted in a configuration in which it is mounted by a reflow method. That is, in this type of crystal oscillator, since it is possible to perform screen printing on the land on the flat wiring board 20 having no step, a large area in which a plurality of wiring boards are connected vertically and horizontally is provided. Batch processing using a 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 by mounting the crystal oscillator on a printed circuit board (not shown) must be increased.
The result is contrary to the demand for high-density mounting of mounted components on a printed circuit board.

[0004]

An object of the present invention is to provide a structure in which a packaged piezoelectric vibrator is fixed above a package portion on which electronic components constituting an oscillation circuit and a temperature compensation circuit are mounted. With a piezoelectric oscillator equipped with a flat board as a wiring board on which electronic components are mounted, cream solder can be screen-printed on lands on the wiring board, and it is possible to respond to mass production by batch processing. Another object of the present invention is to provide a piezoelectric oscillator in which the occupied area is reduced by arranging a packaged crystal resonator three-dimensionally above a wiring board. Another object of the present invention is to use a special column member as a means for electrically and mechanically connecting the wiring board and the crystal unit, thereby enabling manufacturing by batch processing.

[0005]

According to a first aspect of the present invention, there is provided a flat wiring board having at least an electronic component constituting an oscillation circuit mounted on an upper surface and an external electrode provided on a lower surface. A piezoelectric vibrator fixed at a predetermined gap via a column member fixed to the upper surface of the wiring board, wherein the piezoelectric vibrator is placed in a hermetically sealed space in a package. A vibrating element is sealed, and the column member has an upper portion integrated with an outer bottom surface of a package of the piezoelectric vibrator, and a bottom portion connected to an excitation electrode of the piezoelectric vibrating element at a bottom portion of the column member. An electrode is formed, and a column member fixing pattern for fixing a bottom electrode of the column member in a conductive state is formed on an upper surface of the wiring board. According to a second aspect of the present invention, there is provided a flat wiring board having a plurality of electronic components constituting an oscillation circuit and a temperature compensation circuit mounted on an upper surface thereof and having an external electrode on a bottom surface, and a column member fixed to the upper surface of the wiring substrate. A piezoelectric vibrator fixed at a predetermined gap through the piezoelectric vibrator, wherein the piezoelectric vibrator seals the piezoelectric vibrating element in a hermetically sealed space in the package, and has a package outer bottom surface. A bottom electrode electrically connected to an excitation electrode of the piezoelectric vibrating element, wherein the column member is a member separate from the wiring substrate and the piezoelectric vibrator, and a bottom portion of the column member is formed on an upper surface of the wiring substrate. It is characterized in that the column member is electrically and mechanically fixed to the column member fixing pattern, and the upper portion of the column member is electrically and mechanically fixed to the bottom electrode of the piezoelectric vibrator.
The invention according to claim 3 is characterized in that the column member includes a ceramic block, and an upper electrode and a bottom electrode which are formed on the upper and lower portions of the ceramic block and are electrically connected to each other. The invention according to claim 4 is characterized in that the column member is made of a metal block or a metal ball. The invention according to claim 5 is characterized in that the tallest electronic component among the electronic components is used as the column member. The invention according to claim 6 is characterized in that the column member has a circular, elliptical or oval cross-sectional shape.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIGS. 1A and 1B are a vertical 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. The crystal oscillator 31 has a plurality of electronic components 33 constituting an oscillation circuit and a temperature compensation circuit mounted on an upper surface, and is integrated with a flat wiring substrate 32 having an external electrode 34 on a bottom surface and a bottom surface of a package 42. A quartz oscillator 41 is fixedly integrated with the column member (leg member) 43 on the wiring board 32 by fixing the column member (leg member) 43 to the upper surface of the wiring board 32 with a predetermined gap therebetween. The wiring board 32 is made of, for example, ceramic and has, on its upper surface, a land 35 for mounting electronic components and a column member fixing pattern 36 for fixing the bottom electrode 44 of the column member 43 in a conductive state. The column member fixing pattern 36 is electrically connected to the lands 35, the external electrodes 34, and the like. The crystal resonator 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 resonator element 45 supported in the recess. A rectangular column member 43 is integrated at an appropriate position on the bottom surface of the main body 42a, in this example, at four corners. On the bottom surface of the column member 43, a bottom electrode 44 that is electrically connected to the excitation electrode of the crystal resonator element 43 is formed. The package 42 and the column member 43 are made of, for example, ceramic. According to this embodiment, the flat wiring board 32
The cream solder is applied to the upper lands 35 and the pillar member fixing patterns 36 in a lump by screen printing, and the electronic components 33 and the bottom electrodes 44 of the pillar members are mounted on the lands 35 and the pillar member fixing patterns 36, respectively. Then, by heating in the reflow furnace, each electronic component 33 and the quartz oscillator 41 can be fixed on the wiring board 32 respectively. Note that a procedure may be adopted in which only the electronic component 33 is reflow-connected on each land 35, and then the bottom electrode 44 of the column member 43 is fixed with a conductive adhesive. As described above, since the cream solder can be printed on the land 35 and the like on the wiring board 32 by screen printing, batch processing can be performed, and productivity can be improved. Moreover, since the crystal oscillator 41 is arranged in parallel with a predetermined gap between the crystal oscillator 41 and the upper surface of the wiring board 32, the plane area of the crystal oscillator 31 can be reduced.
Further, by setting the bottom area of the column member 43 to be as small as necessary, the effective area that can be used for mounting electronic components can be increased 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 the first embodiment in that the column member is configured as a member separate from the package of the crystal resonator. That is, in the second embodiment, a plurality of electronic components 33 constituting 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; And a piezoelectric vibrator 41 fixed at a predetermined gap via a column member 50 fixed to the upper surface of the wiring substrate 32. In the piezoelectric oscillator, the column member 50 is connected to the wiring substrate 32 and the piezoelectric vibrator 41. It is a separate member, and the bottom of the column member 50 is
2 is characterized in that it is electrically and mechanically fixed to the column member fixing pattern 36 formed on the upper surface, and the upper part of the column member 50 is electrically and mechanically fixed to the bottom electrode of the piezoelectric vibrator. First, the embodiment shown in FIG.
The crystal oscillator 41 is mounted on the column member fixing pattern 36 on the upper side 2 via the column member 50. Wiring board 3
2 is an electronic component 33 on a land 35 formed on the upper surface thereof.
And external electrodes 34 electrically connected to the lands 35 on the bottom surface. In addition, a column member fixing pattern 36 is provided at an appropriate 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 a bottom electrode 46 is provided instead of fixing the column member to the bottom surface of the package body 42a. The pillar member 50 according to this embodiment includes a square pillar or another polygonal pillar-shaped ceramic block 51 (thickness of about 0.3 to 0.5 mm), and a bottom electrode (metallized portion) 52 provided on the bottom of the ceramic block 51. And an upper electrode (metallized portion) 53 provided above the ceramic block 51, and a connection conductor 54 that conducts between the electrodes 52 and 53.

[0008] The pillar member 50 of this embodiment is formed of a wiring board 3
Since the column member 50 is fixed on the column member fixing pattern 36 on the wiring board 32 because the column member 50 and the crystal unit 41 are separate structures, the column member fixing pattern 36 is formed by screen printing. Reflow connection using 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 column member 50 are placed on the land 35 and the column member fixing pattern 36 to which cream solder has been applied, respectively. Then, the electronic component 33 and the column member 50 are fixed by simultaneously heating in the reflow furnace and then cooling. After fixing the column member 50 on the wiring board 32 for the quartz oscillator 41,
The bottom electrode 46 may be fixed on the upper electrode 53 of the column member 50 using a conductive adhesive or the like, or the connection between the upper electrode 53 and the bottom electrode 46 may be performed when the electronic component 33 or the like is reflow-connected. You may implement simultaneously. According to this embodiment,
Since the column member 50 is configured as a member different from the wiring board 32 and the quartz oscillator 41, the mounting and fixing of the electronic component 33 and the column member 50 on the wiring board 32 can be performed by batch processing. Becomes That is, after applying cream solder by screen printing to the land group and the column member fixing pattern group formed on the large area wiring board base material, respectively, the lands 35 and the column member fixing pattern 36 are applied. The electronic component 33 and the column member 50 are provided on the
The connection can be completed by placing the bottom electrode 52 and heating it all together in a 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, the column member 50 is formed of a square or polygonal metal having a thickness of about 0.3 to 0.5 mm. Use blocks. That is, a metal block made of a conductive metal material is used in place of the ceramic block 51, and the column 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 second crystal oscillator can be realized. By using a conductive metal block as the column member 50, as in the case of the ceramic block, the trouble of providing the electrodes 52 and 53 and the connection conductor 54 is unnecessary. Alternatively, a metal ball having a diameter of about 0.3 to 0.5 mm may be used as the column member 50 instead of the metal block. 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 is shown in which the bottom surface electrode 46 on the bottom surface of the crystal unit is connected. 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 a reflow connection using cream solder, respectively, or a conductive adhesive may be used. The connection used may be used. Also in this case, similarly to the case where the metal block is used, the electrodes 52,
The trouble of providing the 53 and the connection conductor 54 becomes unnecessary.

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 in the embodiment shown in FIG. I do. The difference between this embodiment and the crystal oscillator of the embodiment of FIG.
The column member 50 has a configuration in which the tallest electronic component 33A among the chip-type electronic components 33 is used. In the illustrated example, a plurality of tallest electronic components 33A are arranged using a binder such as solder on a column member fixing pattern 36 which also serves as a land provided on the edge of the upper surface of the wiring board 32, and each electronic component 33A is provided. The bottom surface of the package of the crystal unit 41 is fixed to the upper surface of 33A. The upper surface of the electronic component 33 </ b> A is electrically connected to the bottom electrode 46 of the crystal unit 41, so that the crystal unit 45 inside the crystal unit and each electronic component 33,
It is configured to ensure conduction 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, the tall electronic component 33A is selected from among the electronic components 33 to be mounted on the wiring board 32 without preparing a special pillar member.
Is used as a column member, so that 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 column members 43 and 50 are formed by making the plane shape (bottom shape or cross-sectional shape) of the column members 43 and 50 used to be circular or elliptical (including oval).
Even when the column members 43 and 50 are displaced in the rotational direction when the wiring board 32 and the crystal unit 41 are joined via the, the column members 43 and 50 are moved outward from the edge of the wiring board 32. The feature is that it does not protrude.
That is, as shown in FIG. 5 (c), when the planar shape of the column members 43 and 50 is rectangular or another polygon,
If the reference numeral 3 and 50 deviate from the original mounting position indicated by the dotted line in the rotational direction for some reason, the corners are fixed in a state protruding outward from the edge of the wiring board 32, and this becomes a burr. Cause malfunctions. However, as shown in FIGS. 5 (a) and 5 (b), the column members 43 and 50 were slightly rotated by making the planar shape of the column members 43 and 50 circular or elliptical without any corners. As
It does not easily protrude outward from the edge of the wiring board, and even if the peripheral surface of the pillar member protrudes slightly, the corner does not protrude.

[0012]

As described above, according to the present invention, a piezoelectric oscillator having a configuration in which a packaged piezoelectric vibrator is fixed above a package portion on which electronic components constituting an oscillation circuit and a temperature compensation circuit are mounted. By adopting a flat board as the wiring board on which the electronic components are mounted, it is possible to screen-print cream solder on the lands on the wiring board, and it is packaged while supporting mass production by batch processing. By arranging the crystal resonator three-dimensionally above the wiring board, it is possible to provide a piezoelectric oscillator that reduces the occupied area. In addition, 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 manufacture by batch processing. That is, according to the first aspect of the present invention, a column member is previously integrated with the bottom of the piezoelectric vibrator, and this column member is electrically and mechanically connected to the column member fixing pattern on the wiring board. In addition, a piezoelectric oscillator having a small occupied area can be constructed using a flat wiring board. For this reason, 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 column member is a separate member from the wiring substrate and the piezoelectric vibrator, and the bottom of the column member is electrically connected to a column member fixing pattern formed on the upper surface of the wiring substrate. And mechanically fixed, and the upper part of the column member was electrically and mechanically fixed to the bottom electrode of the piezoelectric vibrator, so that the electronic component and the electronic component were formed on the wiring board by batch processing using a large-area wiring board base material. The step of mounting the column member can be performed, and mass productivity can be improved. According to the third aspect of the present invention, the pillar member is made of a ceramic block, and an upper electrode and a bottom electrode formed on the upper and lower portions of the ceramic block and electrically connected to each other. The members can be mass-produced and used. The invention of claim 4 is
Since the metal block or the metal ball is used as the column member, the configuration of the column member can be further simplified, and the productivity can be increased. According to the invention of claim 5, since the tallest electronic component among the electronic components is used as the column member,
It is possible to reduce the number of parts and manufacture without preparing a special column member. According to the invention of claim 6, since the pillar member has a circular, elliptical or elliptical bottom shape, even if the pillar member rotates for some reason, a part of the pillar member is located at the end of the wiring board. No burrs are projected from the edge.

[Brief description of the drawings]

FIGS. 1A and 1B are a vertical 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 configuration 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 view of a crystal oscillator as another example of the piezoelectric oscillator according to the second embodiment of the present 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 present invention.

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

FIGS. 6A and 6B are explanatory diagrams 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 component, 34 external electrode, 35 land, 36 pillar member fixing pattern, 41 crystal oscillator, 42 package, 42a package body, 42b metal cover, 43
Column member, 44 Bottom electrode, 50 Column member, 51 Ceramic block, 52 Bottom electrode (metallized portion), 53
Upper electrode (metallized portion), 54 connection conductor.

Continuation of the front page (72) Inventor Yoji Nagano 2-1-1 Kotani, Samukawa-cho, Koza-gun, Kanagawa F-term in Toyo Tsushinki Co., Ltd. 5J079 AA04 BA43 BA44 HA07 HA09 HA28 HA29 KA05

Claims (6)

[Claims] 1. A flat wiring board having at least an electronic component constituting an oscillation circuit mounted on an upper surface thereof and having an external electrode on a lower surface thereof, and a predetermined gap therebetween via a column member fixed to the upper surface of the wiring substrate. And a piezoelectric vibrator fixed and fixed, wherein the piezoelectric vibrator has a configuration in which a piezoelectric vibrating element is sealed in an airtight space in a package, and the column member has an upper part thereof. The bottom electrode of the column member is formed integrally with the outer bottom surface of the package of the piezoelectric vibrator, and the bottom electrode of the column member is formed with a bottom electrode that is electrically connected to the excitation electrode of the piezoelectric vibration element. Characterized in that a column member fixing pattern for fixing the piezoelectric element in a conductive state is formed. 2. A flat wiring board having a plurality of electronic components constituting an oscillation circuit and a temperature compensating circuit mounted on the upper surface and having external electrodes on the bottom surface, and a column member fixed to the upper surface of the wiring substrate. A piezoelectric vibrator fixed with a predetermined gap therebetween, wherein the piezoelectric vibrator seals the piezoelectric vibrating element in an airtight cavity in the package, and includes A column electrode provided with a bottom electrode electrically connected to an excitation electrode of the piezoelectric vibrating element, wherein the column member is a member separate from the wiring substrate and the piezoelectric vibrator; and a column formed with a bottom portion of the column member on an upper surface of the wiring substrate. A piezoelectric oscillator which is electrically and mechanically fixed to a member fixing pattern, and wherein the upper portion of the column member is electrically and mechanically fixed to a bottom electrode of a piezoelectric vibrator. 3. The method according to claim 1, wherein the column member includes a ceramic block,
3. The piezoelectric oscillator according to claim 2, further comprising: an upper electrode and a bottom electrode formed on the upper and lower portions of the ceramic block, respectively, and connected to each other. 4. The piezoelectric oscillator according to claim 2, wherein said column member is made of a metal block or a metal ball. 5. The piezoelectric oscillator according to claim 2, wherein a tallest electronic component among the electronic components is used as the column member. 6. The column member has a circular cross-sectional shape,
3. An oval or oval shape,
6. The piezoelectric oscillator according to 3, 4, or 5.