JP2006270490A - Surface mounted piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface mounted piezoelectric oscillator in which a piezoelectric diaphragm is stably loaded without obstructing the miniaturization of the surface mounted piezoelectric oscillator, the degree of freedom of the design of a wiring pattern for an integrated circuit element is high, and the reliability of airtight sealing is high. <P>SOLUTION: The surface mounted piezoelectric oscillator is provided with an insulating base 1, the integrated circuit element 2 and the piezoelectric diaphragm 3 constituting a piezoelectric oscillation circuit and a lid 4. The insulating base comprises: a first housing part where the wiring pattern is formed and the integrated circuit element is housed; and a second housing part where a holding base and the wiring pattern are formed and the piezoelectric diaphragm is housed at the upper part of the first housing part. In the first housing part, a wide housing area and a narrow housing area are formed and the wiring pattern for the integrated circuit element is formed more in the wide housing area than in the narrow housing area. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric oscillator in which an integrated circuit element and a piezoelectric vibrator are mounted on a ceramic base to constitute an oscillation circuit, and improves the package structure of a surface mount piezoelectric oscillator.

Due to the demand for surface mounting of parts, piezoelectric oscillators house a piezoelectric vibrator in a ceramic base housing part with a bank around it, cover it with a metal lid on which a brazing material is formed, and seal it hermetically by welding. The structure which stops is common. In recent years, portable electronic devices, such as mobile phones, are becoming lighter, thinner, and smaller. In connection with this, the piezoelectric oscillator which is one of the components of an electronic component is also reduced in size. In particular, along with the trend toward lowering the height and cost of piezoelectric oscillators, the metallization part for sealing formed on the upper part of the embankment part of the ceramic base without interposing the metal ring for sealing on the upper part of the embankment part of the ceramic base On the other hand, the number of types in which a metal lid brazing material is directly welded is increasing. On the other hand, in a surface mount type piezoelectric oscillator constituted by a ceramic base, as shown in Patent Document 1, in order to measure characteristics of a piezoelectric vibrator alone without an integrated circuit element, a ceramic base bank portion is used. In some cases, castellations were formed on the side end portions (outer peripheral portions) of the slabs to form external measurement terminals for piezoelectric vibrators.
JP 2004-214799 A

In such a configuration, by forming the castellation, it is possible to prevent the strength of the ceramic base from being lowered, so that the width of the embankment portion of the ceramic base is secured to a predetermined dimension or more (approximately 0.2 mm or more). And formed. However, if the width of the embankment portion of the ceramic base is extended outward, it will hinder downsizing of the ceramic base, and if the width of the embankment portion of the ceramic base is extended outward, the ceramic base can be stored. There was a problem that the volume of the part became small. In particular, when the piezoelectric diaphragm is housed in the ceramic base housing, if the volume of the housing is reduced, the clearance between the ceramic base bank and the end of the piezoelectric diaphragm is reduced, and the piezoelectric diaphragm to the ceramic base is reduced. There was a problem that could not be mounted stably.

Further, when the integrated circuit element is stored in the ceramic-based storage portion, if the volume of the storage portion is reduced, a plurality of wiring patterns for the integrated circuit are brought close to each other, which impedes the freedom of wiring pattern design. Is done. In general, the wiring patterns exposed on the outer surface of the storage portion can be subjected to an appearance inspection for pattern defects (disconnection, short-circuit), and therefore it is easy to design the wiring patterns close to each other with a reduced pattern width. On the other hand, since the wiring pattern that is not exposed on the outer surface of the storage portion cannot be visually inspected for defective patterns (disconnection, short circuit), the width of the pattern is slightly larger than the exposed wiring, and A design to isolate and place was necessary. When the volume of the ceramic-based storage portion is reduced, the number of wiring patterns that are not exposed on the outer surface in particular increases, which restricts the design of the wiring patterns, and hinders the downsizing of the surface-mount piezoelectric oscillator. .

In addition, in the surface mount type piezoelectric oscillator in which a metal lid brazing material is directly welded to the sealing metallized portion formed on the upper portion of the ceramic base, the castellation and sealing are performed as the size is reduced. At present, the metallized portions are arranged close to each other, and it is difficult to secure a sealing region. In particular, there is a problem that the outer peripheral shape of the sealing metallized portion easily varies depending on the outer peripheral shape of the ceramic base, and the welding region is not stable. Then, the melting region of the metal lid with respect to the sealing metallized portion overlaps the region where the castellation is formed, and the width of the melting region becomes extremely narrow at this portion, causing a leak and causing an airtight defect. There was a thing. Conventionally, in order to cope with this problem of leakage, a method of expanding the melting region of the brazing material by increasing the melting temperature has been taken. However, the method of raising the melting temperature in this manner is more preferable because a problem of splash such as the molten brazing material splashing into the storage portion, a problem of cracking of the base due to the heat distortion of melting, etc. may newly occur. There was no countermeasure at present.

  The present invention has been made in view of the above points, and an object of the present invention is to enable stable mounting of a piezoelectric diaphragm without hindering downsizing of a surface-mounted piezoelectric oscillator, and for an integrated circuit element. It is an object of the present invention to provide a surface mount piezoelectric oscillator having a high degree of freedom in designing a wiring pattern and having a high hermetic sealing reliability.

  In order to achieve the above object, the present invention can be realized by the following configuration.

  That is, according to a first aspect of the present invention, there is provided a surface mount type piezoelectric oscillator having an insulating base and a lid, wherein an integrated circuit element and a piezoelectric diaphragm constituting a piezoelectric oscillation circuit are rectangular in a plan view and are formed on an upper surface. A plurality of wiring patterns for the integrated circuit element are formed, a first storage part for storing the integrated circuit element, a holding base for the piezoelectric diaphragm and the piezoelectric vibration at an upper part of the first storage part A wiring pattern of the daughter board is formed, and a second storage part for storing the piezoelectric diaphragm, a bank part formed around the first storage part and the second storage part, A sealing member formed on the upper surface; and a castellation in which a terminal electrode is formed on a part of a side end of the bank portion; and the first storage portion is formed wide. Adjacent to the dike and narrow dike, wide storage area A narrow storage region, and an insulating base in which the wiring pattern for the integrated circuit element is formed in the wide storage region more than the narrow storage region, and the insulating base is covered. The cover is hermetically sealed, has a rectangular shape in plan view, is formed substantially equal to the insulating base, and has a lid with a sealing material formed on the lower surface.

  According to the first aspect of the present invention, since the wiring pattern for the integrated circuit element is formed in the wide storage area of the first storage section that stores the integrated circuit element, the wiring pattern for the integrated circuit element is formed more than the narrow storage area. By centrally arranging the wiring patterns exposed on the outer surface in the region, a more reliable wiring pattern free from short-circuiting or disconnection can be obtained by visual inspection. In addition, since the wiring pattern exposed on the outer surface is formed in the wide storage area, the width of each wiring pattern can be reduced, and adjacent wiring patterns can be designed close to each other. Therefore, the density of the wiring pattern formed as a whole can be increased without hindering the miniaturization of the surface mount piezoelectric oscillator, and the degree of freedom in designing the wiring pattern can be greatly improved. In other words, a highly practical surface-mount piezoelectric oscillator with high productivity corresponding to downsizing can be obtained.

In addition to the above-described configuration, the castellation is formed in a wide bank portion.

  According to the second aspect of the present invention, in addition to the above-described effects, the castellation is formed on the wide bank portion, so that the welding region is not narrowed by the castellation of the insulating base. Therefore, since a practical welding area can be secured, leaks can be eliminated and airtight defects can be prevented. In addition, since there is no need to increase the melting temperature compared to the normal case, there may be new problems such as splashing, such as the molten brazing material splashing into the storage, and cracking of the base due to melting thermal distortion. Absent. That is, a surface-mount type piezoelectric oscillator having a more reliable hermetic sealing structure can be obtained.

According to a third aspect of the present invention, in addition to the above-described structure, the piezoelectric diaphragm holding base is formed adjacent to a narrow bank portion.

  According to the third aspect of the present invention, in addition to the above-described effects, the holding base for the piezoelectric diaphragm is formed adjacent to the narrow bank, so that the insulating base bank and the piezoelectric vibration are provided. A planar clearance with the board mounting area can be secured. For this reason, it becomes easy to insert the conductive bonding material application nozzle for mounting the piezoelectric diaphragm, so that it becomes easy to control the application position of the conductive bonding material in the mounting area of the piezoelectric vibration plate, and as a result, the piezoelectric vibration plate is stabilized. Can be installed.

In addition to the above structure, a castellation is formed on the wide bank portion, and a holding base for the piezoelectric diaphragm is provided in close contact with the narrow bank portion. It is formed.

  According to claim 4, in addition to the above-described effects, a castellation is formed on the wide bank portion, and a holding base for the piezoelectric diaphragm is formed in close contact with the narrow bank portion. As a result, the insulating base is reinforced by the wide bank portion and the holding table in close contact with the bank portion. That is, it is possible to obtain a very practical surface mount piezoelectric oscillator in which the strength of the entire insulating base is improved.

  According to the present invention, the piezoelectric vibrator can be stably mounted without hindering the downsizing of the surface mount type piezoelectric oscillator, and the degree of freedom in designing the wiring pattern for the integrated circuit element is increased, so that the productivity is high. Thus, a surface-mount type piezoelectric oscillator with higher hermetic sealing reliability can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. A first embodiment of the present invention will be described with reference to FIGS. 1 and 2 by taking a surface-mount crystal oscillator as an example. FIG. 1 is an exploded perspective view showing the first embodiment, and FIG. 2 is a plan view before the metal lid of FIG. 1 is sealed. The surface-mount type crystal oscillator is housed in a ceramic base (insulating base) 1 having a recess having an upper opening, an integrated circuit element 2 housed in the ceramic base, and the upper part in the ceramic base. It consists of a piezoelectric diaphragm 3 and a metal lid 4 joined to the opening of the ceramic base.

  The ceramic base 1 is a rectangular parallelepiped as a whole, and has a configuration in which a ceramic such as alumina and a conductive material such as tungsten are appropriately laminated, and has a concave storage portion 10 when viewed in cross section. The storage unit 10 includes a lower storage unit 10a (first storage unit) and an upper storage unit 10b (second storage unit), in which the piezoelectric diaphragm 3 and the integrated circuit element 2 are stored. A bank portion 11 is formed around the storage portion, and the top surface of the bank portion 11 is flat, and a circumferential first metal layer 11a (a sealing member) is formed on the bank portion. The upper surface of the first metal layer 11a is also formed to be flat, and the metal film layers are formed in the order of tungsten, nickel, and gold. Tungsten is integrally formed during ceramic firing by metallization technology, and nickel and gold layers are formed by plating technology.

  A pair of castellations C1 and C2 extending in the vertical direction are formed at the end portion on the long side of the ceramic base. The castellation has a configuration in which arc-shaped cutouts are formed in the vertical direction.

  The first metal layer 11a is electrically led to an external connection electrode (not shown) formed on the lower surface of the ceramic base by conductive vias B that vertically connect the corners of the ceramic base. Yes. By connecting the external lead electrode to the ground, a metal lid, which will be described later, is grounded through the metal layer 11a and the conductive via B, and an electromagnetic shielding effect of the electronic component can be obtained. As described above, the conductive via B can be formed by a known ceramic lamination technique.

  Inside the ceramic base 1, a lower storage portion 10a (first storage portion) for storing the integrated circuit element 2 and a holding base 10c for a piezoelectric diaphragm described later are formed on the lower surface as described above. Above the lower storage portion 10a (first storage portion), an upper storage portion 10b (second storage portion) having a large volume corresponding to the holding table 10c is formed. On the upper surface of the holding table, electrode pads 12 and 13 (wiring patterns of the piezoelectric diaphragm) are formed side by side in the short side direction at one end in the long side direction. These electrode pads 12 and 13 are formed close to the inside of the ceramic base, and each electrode pad is connected to an external connection terminal electrode (not shown) formed on the lower surface of the ceramic base on the opposite surface by the conductive via B, respectively. As drawn. Further, the electrode pads 12 and 13 are formed on a pair of castellations C1 and C2 extending in the vertical direction at the ends on the long side of the ceramic base. (Not shown).

  The bank portion 11 includes a bank portion 111 formed wide and a bank portion 112 formed narrow. The broadly formed bank portion 111 is formed from the long side of the ceramic base to the region facing the piezoelectric diaphragm holding base 10c from the region where the castellations C1 and C2 are formed. The narrow bank portion 112 is formed in close contact with the short side of the ceramic base and the peripheral region of the piezoelectric diaphragm holding base 10c among the long sides of the ceramic base. That is, the lower storage portion 10a and the upper storage portion 10b adjacent to the bank portion thus formed have a wide storage region 10d and a narrow storage region 10e, respectively. With this configuration, since the castellations C1 and C2 are formed on the wide bank portion 111, the ceramic base welding region is not narrowed by the castellations C1 and C2. For this reason, since a practical welding area can be secured, leakage can be eliminated and airtight defects can be prevented. Further, since the holding base 10c for the piezoelectric diaphragm is formed in close contact with the narrow bank portion 112, a planar clearance between the bank portion 112 and the electrode pads 12 and 13 is ensured. can do. For this reason, it becomes easy to insert the conductive bonding material application nozzle for mounting the piezoelectric diaphragm, so that it becomes easy to control the application position of the conductive bonding material in the mounting area of the piezoelectric vibration plate, and as a result, the piezoelectric vibration plate is stabilized. Can be installed. Moreover, even if the space | interval of the electrode pads 12 and 13 narrows with the miniaturization of a ceramic base. The conductive bonding material applied to the electrode pads 12 and 13 can be isolated as much as possible, and the problem of short circuit is eliminated. Further, the ceramic base is reinforced by the wide bank portion 111 and the holding table 10c in close contact with the bank portion, so that the strength of the entire insulating base is improved.

  A plurality of wiring patterns 16a to the integrated circuit element 2 are formed side by side on the bottom surface of the lower housing portion 10a. At this time, the wiring pattern 16a is formed in the wide storage area 10d more than the narrow storage area 10e. In this embodiment, for example, two wiring patterns 16a are formed for the narrow storage area 10e, and more four wiring patterns 16a are formed for the wide storage area 10d. With this configuration, the wiring pattern 16a exposed on the outer surface is concentrated in the wide storage area 10d, so that a more reliable wiring pattern free from short-circuiting or disconnection can be obtained by visual inspection. In addition, since the wiring pattern exposed on the outer surface is formed in the wide storage region 10d, the width of each wiring pattern can be formed small, and adjacent wiring patterns can be designed close to each other. Therefore, the density of the wiring pattern 16a formed as a whole can be increased without hindering the miniaturization of the surface mount piezoelectric oscillator, and the design flexibility of the wiring pattern 16a can be greatly improved.

  The ceramic base having the above-described configuration is formed by using a known ceramic lamination technique or metallization technique, and the electrode pad and the connection pad are formed of a nickel plating layer on the upper surface of the metallization layer made of tungsten or the like, similar to the formation of the metal layer 11a. In this configuration, each gold plating layer is formed.

  The integrated circuit element 2 mounted in the lower housing part is a one-chip integrated circuit element that constitutes an oscillation circuit together with the piezoelectric diaphragm 3, and a plurality of connection terminals (not shown) are formed on the lower surface thereof. In the present embodiment, the integrated circuit element 2 employs a bare chip, and a plurality of connection terminals of the integrated circuit element and a plurality of connection pads 16a formed in the package are connected by a face-down bonding technique. Note that a resin material may be filled in the gap between the lower housing portion 10b and the integrated circuit element 2.

  A piezoelectric diaphragm 3 is mounted above the integrated circuit element 2 with a predetermined interval. The piezoelectric diaphragm 3 is, for example, a rectangular AT-cut quartz diaphragm, a pair of rectangular excitation electrodes (not shown) facing the front and back surfaces, and an extraction electrode that draws the excitation electrode to the outer periphery of the quartz diaphragm (Not shown). Each of these electrodes can be formed by a thin film forming means such as a vacuum deposition method or a sputtering method.

  For joining the piezoelectric diaphragm and the ceramic base, for example, an appropriate amount of a conductive bonding material (not shown) is supplied from a conductive bonding material application nozzle provided in the dispenser on the upper surfaces of the electrode pads 12 and 13. Thereafter, the piezoelectric diaphragm 2 is mounted on the electrode pads 12 and 13. As a result, the extraction electrode of the piezoelectric diaphragm and the electrode pads 12 and 13 are electrically and mechanically connected. If necessary, a conductive bonding material (not shown) is again applied to the extraction electrode portion of the mounted piezoelectric diaphragm. An overcoat may be applied. The conductive bonding material is in the form of a paste, and examples thereof include a silicone-based conductive resin adhesive containing metal fine pieces such as silver filler. In addition to the silicone-based adhesive, for example, urethane-based, imide-based, polyimide-based An epoxy-based conductive resin adhesive can be used.

  The metal lid 4 that hermetically seals the ceramic base has a flat plate configuration that is rectangular in plan view. The metal lid 4 has a configuration in which a metal brazing material (sealing material) is formed as a second metal layer (not shown) on a core material (not shown) made of Kovar. To a nickel layer, a Kovar core material, a copper layer, and a silver brazing layer in this order, and the silver brazing layer as the second metal layer is joined to the first metal layer of the ceramic base. The external shape of the metal lid in plan view is substantially the same as or slightly smaller than that of the ceramic base.

  The integrated circuit element 2 and the piezoelectric diaphragm 3 are stored in the storage portion 10 of the ceramic base 1, covered with the metal lid, the first metal layer and the second metal layer are melt-cured, and hermetically sealed. I do. In this embodiment, airtight sealing is performed by seam welding without using a metal ring for sealing, and the seam roller runs along the ridges of the long side and the short side of the metal lid, The silver brazing (sealing material), which is the second metal layer formed on the lid, is welded to the first metal layer (sealing member) of the ceramic base 1 to perform hermetic sealing.

  The present invention is not limited to the above-described embodiment, and can be applied, for example, by changing the position of the wide storage region 10d of the ceramic base. FIG. 3 is a plan view showing a second embodiment according to the present invention. Since the basic configuration is the same as that of the first embodiment, the same reference numerals are used for the same components, and a part of the description is omitted.

  In the second embodiment disclosed in FIG. 3 (a), the wide bank portion 111 has the piezoelectric vibration from a region where the castellations C1 and C2 are formed on the long side of the ceramic base. It is formed over the peripheral region of the board holding base 10c. The narrow bank portion 112 is formed in a region where the short side of the ceramic base and the long side of the ceramic base face the holding base 10c for the piezoelectric diaphragm. That is, in FIG. 3A, in contrast to the first embodiment, a narrow storage region 10e exists in a region facing the piezoelectric diaphragm holding base 10c, and a wide storage region 10d is It exists in the peripheral area | region of the holding stand 10c for piezoelectric diaphragms. Two wiring patterns 16a are formed for the narrow storage area 10e, and four wiring patterns 16a are formed for the wide storage area 10d. By configuring in this way, substantially the same operational effects as those of the first embodiment can be obtained. In addition, since the wiring pattern exposed on the outer surface is easily formed in the wide storage area 10d, the wiring pattern can be easily routed, and even if a holding pillow or the like for the piezoelectric diaphragm is additionally formed in the area, the wiring pattern The area hidden from the outer surface of the pattern can be reduced.

  In the second embodiment disclosed in FIG. 3B, the wide bank portion 111 is formed only in the region where the castellations C1 and C2 are formed, and the narrow width is reduced. The formed bank portion 112 is formed for all other regions. That is, in FIG.3 (b), the narrow storage area | region 10e exists only in the center part, and the wide storage areas 10d and 10d exist in the both ends. The wiring pattern 16a is not formed for the narrow storage area 10e, and four wiring patterns 16a are formed for the wide storage areas 10d and 10d at both ends. With this configuration, not only substantially the same operational effects as in the first embodiment can be obtained, but also the wiring pattern density and design flexibility can be improved.

In the above embodiment, the crystal oscillator is described as an example, but the present invention can be applied to other piezoelectric vibration devices such as a crystal resonator and a crystal filter, or other electronic component containers.
An example is hermetic sealing by seam welding without using a metal ring for sealing, but a metal ring for sealing may be used, such as beam sealing such as laser or electron beam, or glass as a sealing material. Glass sealing using may be used.

  The present invention can be implemented in various other forms without departing from the spirit or containment characteristics thereof, and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not limited by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

The disassembled perspective view which shows 1st Embodiment. The top view before sealing the metal cover of FIG. The top view which shows 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic base 2 Integrated circuit element 3 Piezoelectric diaphragm 4 Metal lid

Claims (4)

A surface mount piezoelectric oscillator having an insulating base and a lid,
An integrated circuit element comprising a piezoelectric oscillation circuit and a piezoelectric diaphragm;
A rectangular shape in plan view, a plurality of wiring patterns for the integrated circuit elements are formed on the upper surface, a first storage portion for storing the integrated circuit elements, and the piezoelectric diaphragm on the top of the first storage portion And a wiring pattern for the piezoelectric vibrator plate, a second storage portion for storing the piezoelectric vibration plate, and a periphery of the first storage portion and the second storage portion. A first bank that includes a bank, a sealing member formed on an upper surface of the bank, and a castellation in which a terminal electrode is formed on a side edge of a part of the bank. The portion is adjacent to the wide bank portion and the narrow bank portion, thereby forming a wide storage region and a narrow storage region. The wide storage region includes the narrow bank portion. An insulating base in which a wiring pattern for the integrated circuit element is formed over the storage area;
A lid that is hermetically sealed over the insulating base, has a rectangular shape in plan view, is formed substantially equal to the insulating base, and has a sealing member formed on the lower surface;
Surface mount type piezoelectric oscillator including 2. The surface mount piezoelectric oscillator according to claim 1, wherein the castellation is formed in a wide bank portion. 3. The surface-mount type piezoelectric oscillator according to claim 1, wherein the holding base for the piezoelectric diaphragm is formed adjacent to a narrow bank portion. 2. A surface according to claim 1, wherein a castellation is formed on a wide bank portion, and a holding base for a piezoelectric diaphragm is formed in close contact with the narrow bank portion. Mounting type piezoelectric oscillator.

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