JP5540846B2 - Piezoelectric oscillator - Google Patents

Description

  The present invention relates to a piezoelectric oscillator, and more particularly to a piezoelectric oscillator suitable for miniaturization.

  Piezoelectric oscillators are widely used in electronic devices such as portable communication devices in order to obtain a constant frequency. In recent years, downsizing of electronic devices has been rapidly progressing, and accordingly, further downsizing of piezoelectric oscillators is required.

  As a conventional piezoelectric oscillator, for example, there is a piezoelectric oscillator shown in FIG. In the piezoelectric oscillator shown in the figure, a solder ball 82 and an electronic component 84 such as an IC are joined on a polyimide substrate 80, and a piezoelectric vibrator 86 is joined on the solder ball 82. The piezoelectric vibrator 86 includes a package 86a having a recess 86b formed on the upper surface, a piezoelectric vibrating piece 86c bonded and fixed to the recess 86b with a conductive adhesive 86d, and an upper surface of the package 86a for hermetically sealing the recess 86b. And a lid body 86e joined to the edge portion. A molding agent 88 is filled between the piezoelectric vibrator 86 and the polyimide substrate 80. In such a piezoelectric oscillator, the electronic component 84 is not downsized as compared with the piezoelectric vibrating piece 86c, and it is necessary to secure a mounting area of the electronic component 84 to some extent. Therefore, it is difficult to secure a mounting area for the electronic component 84 when the piezoelectric oscillator is downsized. If the solder ball 82 is made small in order to secure the mounting area of the electronic component 84, there is a problem that conduction failure occurs. Further, there is a problem in that the molding agent 88 has heat and the heat is hardly diffused, and the piezoelectric vibrating piece 86c is adversely affected.

  As another type of piezoelectric oscillator, there is a piezoelectric oscillator described in Patent Document 1. In the piezoelectric oscillator described in Patent Document 1, a piezoelectric vibrating piece and an electronic component are mounted with a planar insulating substrate interposed therebetween, and box-shaped lids are bonded to both sides of the planar insulating substrate. Then, by opening at least one of the side surfaces of the lower lid, the space for mounting the electronic components is widened by the thickness of the wall constituting the side surface, and the joint between the lower lid and the insulating substrate is resin molded. This increases the bonding strength.

Although the piezoelectric oscillator described in Patent Document 1 can widen the space for mounting the electronic component by the thickness of the wall constituting the side surface, the lower side of the electronic component is a flat substrate constituting the lid Since it is covered and a molding agent is used, there is a problem that heat cannot be effectively dissipated.
As another type of piezoelectric oscillator, there is a piezoelectric oscillator in which an electronic component is mounted on the back surface of a piezoelectric vibrator package and no molding agent is used (for example, see Patent Documents 2 to 5).

Japanese Patent Laid-Open No. 2004-357019 JP 2003-318653 A JP 2003-46251 A JP 2004-146966 A Japanese Patent Laid-Open No. 2007-235483

  Although the piezoelectric oscillators described in Patent Documents 2 to 5 do not use a molding agent and have a heat dissipation effect, solder balls and pedestals as external terminals are provided on the lower surface of the package. If it is attempted to secure the same area as before, the solder balls and pedestals occupy the space on the lower surface of the package, and it is difficult to secure the mounting area of the electronic component.

  The present invention has been made paying attention to the above-mentioned conventional problems, and provides a piezoelectric oscillator capable of securing a mounting area of electronic components and enhancing a heat dissipation effect even when the piezoelectric oscillator is downsized. For the purpose.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Application Example 1] A piezoelectric vibrator in which a piezoelectric vibrating piece is housed in a package, conductive legs standing on the outer periphery of the lower surface of the package, and an electronic component mounted on the lower surface of the package A piezoelectric oscillator characterized by the following.

  By adopting the above configuration, the lower surface of the package can be used as a space for mounting electronic components except where the legs are erected. Therefore, even when the piezoelectric oscillator is downsized, the mounting area of the electronic components is secured. can do. In addition, since the electronic component is not surrounded by a wall, no molding agent is used, and the lower side of the electronic component is not covered with the flat substrate and is open, the heat dissipation effect can be enhanced. Further, since the flat substrate is not provided under the electronic component, the piezoelectric oscillator can be reduced in size by the thickness of the flat substrate.

[Application Example 2] The piezoelectric oscillator according to Application Example 1, wherein a hole is provided in the outer periphery of the lower surface of the package, and the leg is inserted into the hole.
By setting it as the said structure, while being able to stand a leg part easily in a package by inserting a leg part into a hole part, connection strength and stability can be improved.

[Application Example 3] The piezoelectric oscillator according to Application Example 1 or 2, wherein an external terminal for electrical connection with the mother substrate is provided on the bottom surface of the leg portion.
With the above configuration, the area of the external terminal can be adjusted by the shape of the bottom surface of the leg portion, so that the area of the external terminal can be ensured even when the piezoelectric oscillator is downsized.

Application Example 4 In the piezoelectric oscillator according to any one of Application Examples 1 to 3, the leg portion has an L-shaped column shape having a protruding portion that protrudes from the lower end portion toward the inside of the package. A piezoelectric oscillator characterized by being a member.
With the above configuration, the leg portion can be stabilized, and when the external terminal is provided on the bottom surface of the leg portion, the area of the external terminal can be sufficiently secured even when the piezoelectric oscillator is downsized.

[Application Example 5] The piezoelectric oscillator according to any one of Application Examples 1 to 3, wherein the leg portion is formed so that a cross-sectional area decreases as it approaches the package side. Oscillator.
By adopting the above configuration, the area that the leg portion occupies the lower surface of the package can be reduced, so that a sufficient mounting area for the electronic component can be secured and an external terminal is provided on the bottom surface of the leg portion. Can secure a sufficient area of the external terminals.

Application Example 6 In the piezoelectric oscillator according to Application Example 5, the leg portion is formed of a right triangular prism, and the inclined surface of the right triangular prism is arranged inward.
By adopting the above-described configuration, the area where the leg portion occupies the lower surface of the package can be reduced, so that the mounting area of the electronic component can be sufficiently secured, and the leg portion does not spread outward, so the piezoelectric oscillator Can be reduced. Further, when the external terminal is provided on the bottom surface of the leg portion, a sufficient area of the external terminal can be secured.

Application Example 7 In the piezoelectric oscillator according to Application Example 5, the leg portion has a truncated pyramid shape.
By setting it as the said structure, the intensity | strength of a leg part and the joint strength of a leg part and a package can be improved. Moreover, since the area which a leg part occupies the lower surface of a package can be made small, the mounting area of an electronic component can fully be ensured. Further, when the external terminal is provided on the bottom surface of the leg portion, a sufficient area of the external terminal can be ensured.

(A) is a center longitudinal cross-sectional view of the piezoelectric oscillator which concerns on embodiment of this invention, (b) is a bottom view of the piezoelectric oscillator which concerns on the embodiment, (c) is a leg part concerning the embodiment. It is a bottom view of the piezoelectric oscillator before attachment. FIG. 3D is a process diagram illustrating the method for manufacturing the piezoelectric oscillator according to the embodiment. (A) is a center longitudinal cross-sectional view of the piezoelectric oscillator which concerns on a 1st modification, (b) is a bottom view of the piezoelectric oscillator which concerns on the same modification. (A) is a center longitudinal cross-sectional view of the piezoelectric oscillator which concerns on a 2nd modification, (b) is a bottom view of the piezoelectric oscillator which concerns on the modification. It is a longitudinal cross-sectional view of the conventional piezoelectric oscillator.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. 1A is a central longitudinal sectional view of a piezoelectric oscillator 1 according to an embodiment of the present invention, FIG. 1B is a bottom view of the piezoelectric oscillator 1, and FIG. 1C is a view before attaching a leg portion. 2 is a bottom view of the piezoelectric oscillator 1 of FIG.

As shown in these drawings, the piezoelectric oscillator 1 includes a piezoelectric vibrator 2, a leg portion 4 erected on the lower surface of the piezoelectric vibrator 2, and an electronic component 6 mounted on the lower surface of the piezoelectric vibrator 2. I have. The electronic component 6 is an IC or a capacitor.
The piezoelectric vibrator 2 includes a substantially rectangular parallelepiped package 22, a piezoelectric vibrating piece 26 housed in the package 22, and a lid 28 that hermetically seals the package 22. The piezoelectric vibrating piece 26 is made of quartz. The package 22 is made of ceramic and has a recess 24 on the upper surface. A mount electrode (not shown) is formed on the bottom surface of the recess 24, and a piezoelectric vibrating piece 26 is fixed to the mount electrode via a conductive adhesive 27. Electrode patterns (not shown) such as excitation electrodes and connection electrodes are formed on the front and back surfaces of the piezoelectric vibrating piece 26.

  The electronic component 6 is mounted on the lower surface of the package 22 (hereinafter also referred to as “rear surface”) by FCB (flip chip bonding). An underfill 8 for preventing a short circuit is applied between the lower surface of the package 22 and the electronic component 6.

  As shown in FIG. 1C, holes 10 that do not penetrate to the inside of the package 22 are provided at the four corners of the lower surface of the package 22. Four leg portions 4 are inserted into each of the four hole portions 10, and the hole portions 10 and the leg portions 4 are bonded to each other by silver paste or the like. The leg portion 4 is formed of a conductive material such as a metal material. Or the leg part 4 may be formed with the ceramic, resin, etc. which formed the material which has electroconductivity on the surface.

  The leg portion 4 is an L-shaped columnar member having a protruding portion 41 protruding from the lower end portion thereof toward the inner side of the package 22. The upper end portion of the leg portion 4 is inserted into the hole portion 10 of the package 22 and is electrically connected to the piezoelectric vibrating piece 26 through the hole portion 10. The bottom surface of the leg 4 is joined to the mother board of the electronic device on which the piezoelectric oscillator 1 is mounted with solder, conductive resin, or the like, and is electrically connected to the mother board as an external terminal. The external terminal is electrically connected to the piezoelectric vibrating piece 26 via the leg 4, the electronic component 6, and an electrode (not shown) provided on the package 22.

In the present embodiment, the four leg portions 4 are erected at the four corners of the lower surface of the package 22, but the present invention is not limited to this, and can be placed at any position on the outer periphery of the lower surface of the package 22 regardless of the shape of the lower surface of the package 22. Any number can be erected.
Next, a method for manufacturing the piezoelectric oscillator 1 will be described with reference to FIG.

  First, the piezoelectric vibrator 2 is assembled (S1). Specifically, by laminating ceramics, the package 22 having the recesses 24 on the upper surface and the holes 10 at the four corners of the back surface is formed. Then, a mount electrode is formed in the recess 24 of the package 22, and the connection electrode of the piezoelectric vibrating piece 26 is bonded and fixed to the mount electrode with a conductive adhesive 27, thereby mounting the piezoelectric vibrating piece 26 on the package 22. After that, after adjusting the oscillation frequency of the piezoelectric vibrating piece 26 by irradiating the piezoelectric vibrating piece 26 with a laser or the like, the lid body 28 is joined to the upper surface of the package 22 and hermetically sealed.

  Next, bump bonding is performed (S2), and metal bumps are formed on the back surface of the package 22. Next, the electronic component 6 is mounted on the back surface of the package 22 by FCB (S3). Next, underfill is applied to the gap between the back surface of the package 22 and the electronic component 6 (S4) and dried (S5).

Next, after silver paste is applied to the hole 10 provided on the back surface of the piezoelectric vibrator 2 (S6), the leg 4 is inserted into the hole 10 (S7) and dried (S8).
Next, the temperature characteristics are inspected (S9), the electrical characteristics are inspected (S10), and then stamped and taped (S11).
The electronic component 6 may be fixed to the package 22 with an adhesive, not limited to the FCB. In this case, wire bonding is performed.

  As described above, since the lower surface of the package 22 can be used as a space for mounting the electronic component 6 except for the region where the leg portions 4 at the four corners are provided, the electronic component 6 can be used even when the piezoelectric oscillator 1 is downsized. Mounting area can be secured. Further, since the electronic component 6 is not surrounded by a wall, a molding agent is not used, and a flat substrate or the like is not provided under the electronic component and is open, the heat dissipation effect is enhanced. And the influence of heat on the piezoelectric vibrating piece 26 can be prevented. In addition, since the flat substrate or the like is not provided under the electronic component, the piezoelectric oscillator can be reduced in size by the thickness of the flat substrate. Further, by fitting the leg portion 4 into the hole portion 10, the leg portion 4 can be easily connected to the package 22, and the connection strength between the package 22 and the leg portion 4 can be increased. In addition, by forming the leg portion 4 in an L shape, the leg portion 4 can be stabilized and a sufficient area as an external terminal that is electrically connected to the mother substrate can be secured.

  Further, in the manufacturing process of the piezoelectric oscillator 1, the leg 4 is inserted into the hole 10 of the package 22 after the electronic component 6 is mounted on the lower surface of the package 22. The provided protruding portion 41 does not get in the way, and the large electronic component 6 can be mounted.

Next, a modification of the leg portion will be described. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
FIG. 3A is a central longitudinal sectional view of the piezoelectric oscillator 1a according to the first modification, and FIG. 3B is a bottom view of the piezoelectric oscillator 1a. As shown in FIG. 3A, the leg portion 4a of the piezoelectric oscillator 1a according to the present modification has a right triangular prism shape whose slope is inclined inward as the distance from the package 22 side increases.

  Since the leg portion 4a according to the present modification has a lateral thickness that decreases as it approaches the package 22 side and the cross-sectional area decreases, the area occupied by the leg portion 4a on the lower surface of the package 22 is the leg portion according to the above-described embodiment. 4 and the mounting area of the electronic component 6 can be secured larger. On the other hand, since the bottom surface of the leg portion 4a can secure a sufficient area, the function as an external terminal that is electrically connected to the mother substrate can be ensured. Moreover, since the leg part 4a does not expand in the outer direction of the package 22, the piezoelectric oscillator 1a can be made small.

FIG. 4A is a central longitudinal sectional view of a piezoelectric oscillator 1b according to a second modification, and FIG. 4B is a bottom view of the piezoelectric oscillator 1b. As shown in these drawings, the leg 4b of the piezoelectric oscillator 1b according to the present modification has a quadrangular pyramid shape.
The leg portion 4b according to the present modification has a smaller cross-sectional area as it approaches the package 22 side. Therefore, the area occupied by the leg portion 4b on the lower surface of the package 22 can be reduced, and the area for mounting the electronic component 6 can be increased. Can take. On the other hand, since the bottom surface of the leg portion 4a can secure a sufficient area, the function as an external terminal that is electrically connected to the mother substrate can be ensured. Further, the quadrangular pyramid shaped leg 4b can stabilize the joining with the package 22 and improve the joining strength as compared with the leg 4a having the right triangular prism shape.

Note that the shape of the leg 4b is not limited to a quadrangular pyramid, and may be an arbitrary pyramid shape. Moreover, the shape of a truncated cone may be sufficient.
In addition to the shape described in the above-described modification, the mounting area of the electronic component 6 on the lower surface of the package 22 can be sufficiently secured by making the leg portion have a shape in which the cross-sectional area becomes smaller as the package 22 is approached. In addition, it is possible to secure an area as an external terminal on the bottom surface of the leg portion, and the heat dissipation effect can be enhanced.

1, 1a, 1b ......... Piezoelectric oscillator, 2 ......... Piezoelectric vibrator, 4, 4a, 4b ......... Legs, 6 ......... Electronic components, 8 ......... Underfill, 10 ......... Hole , 22 ...... Package, 24 ...... Recess, 26 ...... Piezoelectric vibrating piece, 27 ...... Conductive adhesive, 28 ...... Lid, 41 ... Projection.

Claims (7)

A piezoelectric vibrator containing a piezoelectric vibrating piece in a package;
Conductive legs,
An electronic component mounted on the lower surface of the package ,
One end of the leg is connected to the lower surface of the package outside the region where the electronic component is disposed, and the other end is the one end in plan view. A piezoelectric oscillator characterized by being a columnar member having a protruding portion protruding inward of the package . Wherein the lower surface of the package has a hole portion is provided, a piezoelectric oscillator according to claim 1, characterized in that said one end of the leg portion is inserted into the hole. 3. The piezoelectric oscillator according to claim 1, wherein the protruding portion is provided with an external terminal that is electrically connected to the mother substrate. A piezoelectric vibrator containing a piezoelectric vibrating piece in a package;
Conductive legs,
An electronic component mounted on the lower surface of the package;
With
The leg portion is formed such that one end portion is connected to the lower surface of the package outside the region where the electronic component is disposed, and the cross-sectional area decreases as it approaches the package side. and pressure electrostatic oscillator characterized by that.   5. The piezoelectric oscillator according to claim 4, wherein an external terminal is provided at the other end of the leg portion to be electrically connected to the mother substrate. The leg is formed of a right triangular prism,
6. The piezoelectric oscillator according to claim 4, wherein the inclined surface of the right triangular prism is arranged inward.   The piezoelectric oscillator according to claim 4, wherein the leg portion has a truncated pyramid shape.

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