JP2017118473A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator in which influence of a noise from a mounting terminal for an electric power is reduced, and which has an excellent phase noise characteristic.SOLUTION: A quartz crystal oscillator 1 is constructed so that an insulation substrate 3 housing an oscillation circuit element 13 is combined to an outer bottom surface of a quartz resonator 2. In the outer bottom surface of a container 4 of the quartz resonator 2, a pair of bottom part electrodes 8b and 8d conducted with a quartz element 7 and bottom part electrodes 8a and 8c for a pair of shields which is conducted a metal lid 9 without being conducted to the quartz element 7 are formed. The bottom part electrode 8c for the shields is electrically connected to a mounting terminal 12c for a ground of the insulation substrate. The bottom part electrode 8a for the shields is positioned at an upper direction of the mounting terminal 12a for a power supply of the insulation substrate, and is electrically mechanically combined to a combination electrode 10a which is not electrically connected to an oscillation circuit element mounting pad 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric oscillator in which a piezoelectric vibrator is bonded and integrated on an insulating substrate that houses an oscillation circuit element.

  As a simple and low-cost piezoelectric oscillator, a so-called two-stage stacked structure is known in which an outer bottom surface of a piezoelectric vibrator is conductively bonded to an upper portion of an insulating substrate that houses an oscillation circuit element. A piezoelectric oscillator having such a structure is disclosed in Patent Document 1, for example.

  The piezoelectric vibrator includes a piezoelectric element, a container that accommodates the piezoelectric element, and a lid that is bonded to the container. The entire piezoelectric vibrator is a substantially rectangular parallelepiped package. The piezoelectric element is cantilevered at its end on a mounting electrode for mounting the piezoelectric element via a conductive adhesive. At the four corners of the outer bottom surface of the container, which is the outer bottom surface of the piezoelectric vibrator, four bottom electrodes led out from the piezoelectric element are formed.

  On the other hand, the insulating substrate is provided with a concave portion opened upward to accommodate the oscillation circuit element. The upper surface of the side wall that surrounds the recess has a substantially rectangular frame shape in plan view, and four junction electrodes corresponding to the bottom electrode are formed at the four corners of the upper surface of the side wall. A plurality of mounting terminals are formed on the opposite surface (outer bottom surface of the piezoelectric oscillator) opposite to the inner bottom surface of the recess of the insulating substrate. The plurality of mounting terminals include mounting terminals for power, output, and ground.

  The four bottom electrodes of the piezoelectric vibrator and the four bonding electrodes of the insulating substrate are conductively bonded on a one-to-one basis via a bonding material. For example, Patent Document 2 discloses the positional relationship between the bottom electrode of the piezoelectric vibrator and the mounting terminal of the insulating substrate after the conductive bonding. However, in the case of the surface mount crystal oscillator in Patent Document 2, since the bottom electrode electrically connected to the piezoelectric element is located above the power supply mounting terminal (14d), the piezoelectric element is interposed via the bottom electrode. It becomes easy to be affected by noise from the mounting terminal for power supply. Also, in the case where the mounting electrode for mounting the piezoelectric element is located above the power supply mounting terminal, the piezoelectric element is easily affected by noise from the power supply mounting terminal. As described above, there is a problem that the phase noise (phase noise) characteristics of the piezoelectric oscillator deteriorate due to the influence of noise from the mounting terminal on the piezoelectric element.

Japanese Patent No. 2974622 Japanese Patent No. 3423253

  The present invention has been made in view of the above point, and an object of the present invention is to provide a piezoelectric oscillator having excellent phase noise characteristics by reducing the influence of noise from a power supply mounting terminal.

  In order to achieve the above object, the present invention provides a piezoelectric oscillator in which an insulating substrate containing an oscillation circuit element is bonded to the outer bottom surface of a piezoelectric vibrator, the piezoelectric vibrator comprising the piezoelectric element and the piezoelectric vibrator. A container containing the element; and a metal lid; a pair of bottom electrodes electrically connected to the piezoelectric element on the outer bottom surface of the container; and not electrically connected to the piezoelectric element; A pair of shield bottom electrodes electrically connected to the lid is formed, and the insulating substrate includes a plurality of oscillation circuit element mounting pads, a plurality of mounting terminals drawn from the pads, and the plurality of the plurality of mounting terminals. A bonding electrode corresponding to the bottom electrode and electrically connected to a part of the oscillation circuit element mounting pad, and the plurality of mounting terminals include a power supply mounting terminal and a ground mounting terminal. The bottom electrode for the pair of shields One is electrically connected to the ground mounting terminal, and the other is electrically connected to a bonding electrode positioned above the power supply mounting terminal and not electrically connected to the oscillation circuit element mounting pad. Mechanically joined.

  According to the said invention, the influence of the noise from the mounting terminal for power supplies can be reduced. One shield bottom electrode electrically connected to the ground mounting terminal of the insulating substrate is electrically connected to the other shield bottom electrode via the lid of the piezoelectric vibrator, and The other shield bottom electrode is located above the power supply mounting terminal. The bonding electrode positioned above the power supply mounting terminal is not electrically connected to the oscillation circuit element mounting pad, and is an electrically independent electrode. Then, the bottom electrode for the other shield is electromechanically joined to the junction electrode located above the power supply mounting terminal, so that the junction electrode located above the power supply mounting terminal is also ground potential. It becomes. That is, since the ground layer is formed above the power supply mounting terminal by the above configuration, noise from the power supply mounting terminal can be blocked by the ground layer.

  In order to achieve the above object, a mounting electrode on which a piezoelectric element is mounted is formed on the container of the piezoelectric vibrator, and at least a part of the mounting electrode is superimposed on the bottom electrode for shielding in plan view transmission. May be.

  According to the said invention, the influence of the noise from the mounting terminal for power supplies can be reduced more. This is because the bottom electrode for the shield connected to the ground is located above the power supply mounting terminal, so that the noise from the power supply mounting terminal is blocked and at least a part of the mounting electrode is transparent in plan view. This is because the propagation of noise to the piezoelectric element joined to the mounting electrode is suppressed by overlapping with the bottom electrode for shielding.

  In order to achieve the above object, the insulating substrate includes a recess in which the oscillation circuit element is accommodated, and the plurality of oscillation circuit element mounting pads on the inner bottom surface of the recess, and a pair of the piezoelectric vibrators Even if the other bottom electrode of the shield overlaps with a portion exposed in the concave portion of the insulating substrate of the wiring pattern drawn from the oscillation circuit element mounting pad to the power supply mounting terminal in a plan view. Good.

  According to the said invention, the influence of the noise from the mounting terminal for power supplies can be reduced more. Of the wiring pattern drawn out from the oscillation circuit element mounting pad to the power supply mounting terminal, the portion exposed in the concave portion of the insulating substrate is open, so that the noise propagated from the power supply mounting terminal is upward. It becomes easy to diffuse. On the other hand, in the configuration according to the present invention, the other of the pair of shield bottom electrodes of the piezoelectric vibrator is overlapped with the exposed portion of the wiring pattern connected to the power supply mounting terminal. Therefore, the influence of noise from the power supply mounting terminal can be further reduced.

  The other of the pair of shield bottom electrodes of the piezoelectric vibrator is a region of the wiring pattern drawn out from the oscillation circuit element mounting pad to the power supply mounting terminal and covered by the side wall of the insulating substrate. A part or all of them may be superimposed in a plan view.

  In the case of the above configuration, the influence of noise from the power supply mounting terminals can be further reduced. This is because, in plan view, a part or all of the region covered by the side wall of the insulating substrate of the wiring pattern in which the other of the pair of shield bottom electrodes of the piezoelectric vibrator is drawn out to the power supply mounting terminal is shown. This is because the effect of noise not only from the power supply mounting terminal but also from the region covered by the side wall of the insulating substrate of the wiring pattern drawn out to the mounting terminal can be suppressed.

  Moreover, in order to achieve the said objective, the structure which the mounting terminal for the power supplies of the said insulated substrate does not overlap with the mounting electrode of the said piezoelectric vibrator by planar view transmission may be sufficient.

  According to the said invention, the influence of the noise from the mounting terminal for power supplies can be reduced more. This is because the ground layer is formed above the power supply mounting terminal, so that not only can the noise from the power supply mounting terminal be blocked by the ground layer, but also the power supply mounting terminal of the insulating substrate can be seen through in plan view. This is because the influence of noise from the power supply mounting terminal can be further reduced by disposing the vibrator so as not to overlap with the mounting electrode of the vibrator.

  As described above, it is possible to provide a piezoelectric oscillator having excellent phase noise characteristics by reducing the influence of noise from a power supply mounting terminal.

1 is a schematic cross-sectional view of a crystal oscillator according to an embodiment of the present invention. The bottom face schematic diagram of the crystal oscillator concerning the embodiment of the present invention. Schematic top view of an insulating substrate according to an embodiment of the present invention. Schematic bottom view of insulating substrate according to an embodiment of the present invention Schematic top view of an oscillation circuit element mounted on an insulating substrate according to an embodiment of the present invention Schematic transmission seen from above the insulating substrate according to the embodiment of the present invention. Schematic transmission seen from above the insulating substrate according to the embodiment of the present invention. The upper surface schematic diagram of the insulated substrate which concerns on the modification of embodiment of this invention. The fragmentary sectional view of the crystal oscillator concerning the modification of the embodiment of the present invention

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 7, taking a crystal oscillator (TCXO) having a temperature compensation function as an example. FIG. 1 is a schematic sectional view of a crystal oscillator according to an embodiment of the present invention. The crystal oscillator 1 has a substantially rectangular parallelepiped shape as a whole, and has a substantially rectangular shape in plan view. In the present embodiment, the external dimensions of the crystal oscillator 1 in plan view are 1.65 mm for the long side and 1.25 mm for the short side. The external dimensions in plan view of the crystal oscillator described above are merely examples, and package sizes other than the external dimensions may be used.

  The crystal oscillator 1 has a so-called “two-stage stacked structure” in which a crystal resonator 2 is conductively bonded to an upper portion of an insulating substrate 3 containing an oscillation circuit element via a bonding material 14 (solder). In the crystal oscillator 1, four mounting terminals 12 provided at four corners of the outer bottom surface 301 of the insulating substrate are joined to an external substrate via solder or the like. In the following, a description will be given of the crystal oscillator and the insulating substrate constituting the crystal oscillator.

  First, an outline of the crystal resonator 2 will be described with reference to FIGS. The crystal resonator 2 is a surface-mount type piezoelectric resonator made of a rectangular parallelepiped package, and a crystal element 7, a container 4 and a lid 9 are main constituent members.

  The crystal element 7 shown in FIG. 1 is a piezoelectric element having a rectangular shape in plan view in which various electrodes are formed on the front and back main surfaces of an AT-cut crystal diaphragm. A pair of excitation electrodes E and E are formed on each of the front and back main surfaces of the crystal diaphragm so as to face each other with the crystal diaphragm interposed therebetween. An extraction electrode is extracted from each of the pair of excitation electrodes toward one end side of the long side of the quartz crystal diaphragm. Each terminal portion of the pair of lead electrodes is an electrode for bonding (adhesive electrode). In FIG. 1, only the excitation electrode (E) is shown, and the drawing electrode and the adhesive electrode are not shown.

  The container 4 is a box-shaped container body whose upper part is open, and has a substantially rectangular shape in plan view. The container 4 includes a flat bottom plate portion 40 made of an insulating material and a metal frame portion 5 attached to the outer peripheral portion of the upper surface of the bottom plate portion 40. The bottom plate portion 40 is composed of two layers (a first layer 41 as a lower layer and a second layer 42 as an upper layer) made of ceramic green sheets. A tungsten (W) metallization layer (not shown) is formed in a frame shape on the outer peripheral portion of the upper surface of the second layer 42, and a frame portion 5 made of Kovar is placed on the metallization layer via a brazing material. It is attached. The outer peripheral edge and the inner peripheral edge of the frame part 5 are substantially rectangular in a plan view, and a lid 9 is seam welded to the upper surface of the frame part 5 via a sealing material.

  As shown in FIG. 1, a space surrounded by the frame portion 5 and the upper surface of the second layer 42 of the bottom plate portion is a concave portion C1, and is substantially rectangular in plan view. On one short side of the inner bottom surface 420 (the upper surface of the second layer 42) of the recess C1, a pair of mounting electrodes 6 and 6 that are conductively bonded to the crystal element 7 are formed in parallel (in FIG. 1). Only one mounted electrode is shown). On the pair of mounting electrodes 6 and 6, the pair of adhesive electrodes (not shown) of the crystal element 7 described above are conductively bonded one-to-one via the conductive adhesive S. As a result, one end side of the long side of the crystal element 7 is cantilevered and bonded onto the mounting electrode 6. In this embodiment, a silicone-based conductive resin adhesive is used for the conductive adhesive S, but a conductive resin adhesive other than a silicone-based adhesive may be used.

  FIG. 2 is a schematic bottom view of the crystal resonator according to the embodiment of the present invention, and the outer bottom surface 410 (the lower surface of the first layer 41) of the container 4 serving as the outer bottom surface of the crystal resonator is substantially rectangular in plan view. Yes. A bottom electrode 8 (8a, 8b, 8c, 8d) is formed at each of the four corners of the outer bottom surface 410. Note that one corner of the bottom electrode 8a is chamfered as a mark for identifying the directionality of the four bottom electrodes.

  In the present embodiment, the mounting electrode 6 and the bottom electrode 8 have a laminated structure of three kinds of metals. Specifically, in these electrodes, a tungsten layer is formed by printing on the base material (ceramic) of the container, and a plating layer is formed on the tungsten layer by an electrolytic plating method in the order of a nickel plating layer and a gold plating layer. Are stacked. As described above, the mounting electrode, the bottom electrode, and the like are formed in a lump. In addition, the metal material which comprises each layer of the electrode mentioned above is an example, and you may use another metal material. For example, molybdenum may be used instead of tungsten.

  As shown in FIG. 2, the four corners of the outer bottom surface 410 of the substantially rectangular container in plan view are notched in a quarter circle in plan view. Specifically, each of the four ridges on the outer side surface of the bottom plate portion 40 of the container is notched so as to penetrate the bottom plate portion 40 in the thickness direction, and the inner wall surface of each of these four notched portions. Of these, the conductor is deposited only for the thickness of the first layer 41. In this way, a part of the inner wall surface of the part cut into a quarter columnar shape is referred to as a castellation, and is indicated by reference numerals 40a, 40b, 40c, and 40d in FIG. Yes. Each of the conductors in the castellations 40a to 40d is electrically connected to each of the bottom electrodes 8a, 8b, 8c, and 8d of the outer bottom surface 410 through the quarter-shaped lead portions L1, L2, L3, and L4. Connected.

  In the present embodiment, four vias (only two vias V1 and V2 are shown in FIG. 1) in which a conductor is filled in a through-hole penetrating the inside of the second layer 42 in the thickness direction in the bottom plate portion 40 are shown. Is formed. One end of each of these four vias is exposed on the upper surface of the second layer 42. Of these, one end side of each of the vias V1 and V2 is connected to a metallization layer (not shown) on the outer peripheral portion of the upper surface of the second layer 42, and is electrically connected to the metal frame 5 attached on the metallization layer. Connected. On the other hand, the other end side of the via V1 is finally drawn out to the bottom electrode 8a via the castellation 40a. Similarly, the other end side of the via V2 is finally drawn out to the bottom electrode 8c via the castellation 40c.

  Of the four bottom electrodes 8a, 8b, 8c, and 8d, the bottom electrode 8b is not shown, and includes a castellation 40b, internal wiring (not shown) provided between the first layer 41 and the second layer 42, and the like. It is electrically connected to one of the pair of mounting electrodes 6 via a via. The bottom electrode 8d is connected to the other of the pair of mounting electrodes 6 via a castellation 40d, internal wiring (not shown) provided between the first layer 41 and the second layer 42, and a via (not shown). And are electrically connected. That is, the bottom electrodes 8b and 8d are electrodes (crystal electrodes) connected to the crystal element 7.

  Of the four bottom electrodes 8a, 8b, 8c, 8d, the bottom electrodes 8a, 8c are electrically connected to the lid 9 via the frame portion 5 as described above, and are not electrically connected to the mounting electrode 6. It is a shielding electrode (hereinafter abbreviated as a shielding electrode). 2, a part of each of the pair of mounting electrodes 6 and 6 is transparent in a plan view and overlaps with the bottom electrode 8a that is a shield electrode and the bottom electrode 8d that is a crystal electrode, respectively. .

The lid 9 is a metal flat plate having a substantially rectangular shape in plan view. The cover 9 is made of Kovar as a base material, and the surface of the base material is plated with nickel and gold. A sealing material is formed in a frame shape on the outer peripheral portion of the main surface on the side joined to the frame portion 5 of the lid.
The above is the outline of the crystal resonator. Next, the insulating substrate will be described with reference to FIGS. 1 and 3 to 4.

  The insulating substrate 3 is a box-shaped container body having an open top, and has a substantially rectangular shape in plan view. The insulating substrate 3 is integrally formed by firing in a state where two ceramic green sheets are laminated. Specifically, as shown in FIG. 1, the insulating substrate 3 includes a flat plate-like first layer 30 and a frame-like second layer 31 laminated on the outer peripheral portion of the upper surface of the first layer 30. A space surrounded by the upper surface of the first layer 30 and the second layer 31 is a recess C2. That is, the second layer 31 is a side wall that surrounds the recess C2. FIG. 3 shows a state in which the oscillation circuit element 13 is not mounted in the recess C2, and the position of the bottom electrode 8 in a state where the crystal resonator 2 is bonded onto the insulating substrate 3 is transparently displayed with a dotted line. Yes.

  As shown in FIG. 3, the concave portion C2 is a space in which the oscillation circuit element 13 is accommodated, and has a substantially rectangular shape in plan view. Six oscillation circuit element mounting pads 11 (11a to 11f) are formed on the inner bottom surface 300 (the upper surface of the first layer 30) of the recess C2, and a part of the wiring pattern drawn out from these pads is formed. Exposed.

  In the present embodiment, the oscillation circuit element 13 is an integrated circuit element (bare chip IC) in which an oscillation circuit, a temperature sensor, a temperature compensation circuit, and the like are integrated on a single chip, and the appearance thereof is a rectangular parallelepiped. Then, six functional terminals (not shown) are provided on the circuit surface side of the oscillation circuit element 13, and the oscillation circuit is interposed via the metal bumps B with the circuit surface side facing the inner bottom surface of the recess C2 of the insulating substrate. The element mounting pads 11a to 11f are ultrasonically bonded (Flip Chip Bonding).

  Further, in this embodiment, after the oscillation circuit element 13 is mounted on the oscillation circuit element mounting pad, an underfill agent is injected from the gap between the oscillation circuit element 13 and the side wall of the insulating substrate, and the oscillation circuit element 13 and the recess C2 are injected. After spreading the underfill agent in the gap with the inner bottom surface 300, the underfill agent is cured. The symbol R in FIG. 1 represents the state after the underfill agent is cured. In this embodiment, an epoxy resin is used as the underfill agent. Thus, by spreading the underfill agent in the gap between the oscillation circuit element and the inner bottom surface of the recess, the bonding reliability of the oscillation circuit element 13 to the insulating substrate 3 can be improved.

  The lower surface 301 (outer bottom surface of the crystal oscillator) of the first layer 30 of the insulating substrate has a substantially rectangular shape in plan view as shown in FIG. 4, and the mounting terminals are joined to the external substrate via solder or the like at the four corners. 12 (12a, 12b, 12c, 12d) are formed. In the present embodiment, the mounting terminal 12a is a power supply terminal (DC), the mounting terminal 12b is for output, the mounting terminal 12c is for grounding (ground), and the mounting terminal 12d is for frequency control (or grounding). It has become. As a mark for identifying the directionality of the four mounting terminals, only the mounting terminal 12d has a planar shape different from other mounting terminals.

  The four corners of the insulating substrate having a substantially rectangular shape in plan view are cut out into a quarter of a circle in plan view. Specifically, each of the four ridges on the outer surface of the first layer 30 and the second layer 31 of the insulating substrate is cut out so as to penetrate in the thickness direction of the container. Of the inner wall surface of each part, the conductor is attached only to the thickness of the first layer 30. In FIG. 3, a castellation 33 (33 a, 33 b, 33 c, 33 d) is shown in which a conductor is attached to a part of the inner wall surface of a portion cut into a quarter columnar shape.

  The upper surface 310 (upper surface of the side wall) of the second layer 31 shown in FIG. 3 is a flat surface, and four bonding electrodes 10a, 10b, 10c, and 10d are formed at the four corners of the upper surface. These four bonding electrodes 10a, 10b, 10c, and 10d have a one-to-one correspondence with the four bottom electrodes 8a, 8b, 8c, and 8d provided on the outer bottom surface 410 of the crystal resonator 2. That is, the bonding electrode 10a corresponds to the bottom electrode 8a, the bonding electrode 10b corresponds to the bottom electrode 8b, the bonding electrode 10c corresponds to the bottom electrode 8c, and the bonding electrode 10d corresponds to the bottom electrode 8d.

  The bonding electrode 10 (10a to 10d) has a shape in plan view that is bent into an alphabetic “L” shape. That is, the bonding electrode 10 is provided so as to be along a virtual corner portion of the substantially rectangular concave portion C2 in plan view (because the corner portion is curved in FIG. 3) and two adjacent sides across the corner portion. It is formed on the upper surface of the side wall (the upper surface 310 of the second layer 31). That is, the inner peripheral edge of the bonding electrode 10 is formed along the inner peripheral edge of the side wall. On the other hand, corners of the outer peripheral edge of the bonding electrode 10 that are close to the castellations 33a to 33d of the insulating substrate are cut out into a quarter circle in plan view. In addition, the corner | angular part close | similar to the castellations 33a-33d of the insulated substrate of the joining electrode 10 does not need to be a quarter circle shape by planar view. For example, the structure which notched the said corner | angular part in C surface shape may be sufficient. Moreover, the structure (right angle) which does not cut off the said corner | angular part may be sufficient.

  A pair of opposing long sides of the side wall of the insulating substrate has four vias (half vias) V3, V4, V5, in which the inner wall surface of the side wall is cut into a semi-cylindrical shape and the inside is filled with a conductor. V6 is formed (see FIG. 6 described later). That is, the four vias V3 to V6 are exposed on the inner wall surface of the side wall on the long side of the insulating substrate. One end side of each of these four vias V3 to V6 is electrically connected to the four junction electrodes 10a to 10d in a one-to-one relationship.

  On the other hand, the other end side of each of the vias V3 to V6 is connected to the oscillation circuit element mounting pad 11b via the wiring pattern on the other end side of the via V4. The other end of the via V6 is connected to the oscillation circuit element mounting pad 11e via a wiring pattern (see FIG. 6). The other end side of the via V5 is connected to the oscillation circuit element mounting pad 11d, and the other end side of the via V3 is not connected to any oscillation circuit element mounting pad. That is, the bonding electrode 10a is a shielding electrode (a so-called NC (Non Connection) terminal). The joining electrodes 10b and 10d are terminals for crystal, and the joining electrode 10c is a terminal for ground.

Of the six oscillator circuit element mounting pads, four pads 11a, 11c, 11d, and 11f are casters 33a to 33 at four corners on the upper surface of the first layer 30 through wiring patterns 15a, 15c, 15d, and 15f, respectively. It is drawn out to 33d, and is drawn out one-to-one to mounting terminals 12a to 12d on the lower surface 301 of the first layer 30 of the insulating substrate via casters 33a to 33d.
The above is the outline of the insulating substrate.

  As described above, the oscillation circuit element mounting pads 11b and 11e, which are crystal terminals, are electrically connected to the bonding electrodes 10b and 10d via the wiring patterns 15b and 15e and the vias V4 and V6, respectively. Oscillator circuit element mounting pads 11b and 11e are finally formed on the front and back main surfaces of the crystal element 7 by conductively bonding the bottom electrodes 8b and 8d of the crystal resonator to the bonded electrodes 10b and 10d, respectively. The excited electrodes E and E are electrically connected to each other.

  On the other hand, the bonding electrode 10c is connected to the ground mounting terminal 12c through the via V5 and the wiring pattern 15d. The bonding electrode 10c of the insulating substrate is conductively bonded to the bottom electrode 8c that is a shielding electrode of the crystal resonator. The bottom electrode 8c is electrically connected to the bottom electrode 8a, which is a shield electrode of the crystal resonator, through the frame portion 5 and the lid 7. The bottom electrode 8a is conductively bonded to the bonding electrode 10a of the insulating substrate. That is, the bottom electrode 8a and the bonding electrode 10a bonded to the electrode have a ground potential. The bonding electrode 10a is located above the mounting electrode 12a, which is a power supply terminal. Furthermore, as shown in FIG. 5, most of the mounting electrode 6 on which the crystal element is mounted overlaps with the bottom electrode 8a that is ground-connected in plan view. With such a configuration, noise from the power supply mounting terminal 12a is blocked by the ground-connected bottom electrode 8a, and most of the mounting electrode 6 is superimposed on the bottom electrode 8a. The influence of noise from the mounting terminal 12a can be reduced. As a result, the phase noise characteristics of the crystal oscillator can be improved.

  In the crystal resonator 2 according to the present embodiment, as shown by a dotted line in FIG. 2, a part of the mounting electrode 6 is superimposed on the bottom electrode 8 a that is a shield electrode in plan view transmission.

  According to the said structure, the influence of the noise from the mounting terminal 12a for power supplies can be reduced more. This is because the shield electrode (bottom electrode 8a) connected to the ground is located above the power supply mounting terminal 12a, so that noise from the power supply mounting terminal 12a is blocked and one of the mounting electrodes 6 is provided. This is because the propagation of the noise to the crystal element 7 bonded to the mounting electrode 6 is suppressed when the portion is overlapped with the shielding electrode (8a) in plan view.

  In this embodiment, as shown in FIGS. 3 and 5, the other of the pair of shield electrodes (8a, 8c) (8a) of the crystal resonator 2 is mounted from the oscillation circuit element mounting pad 11a for power supply. The wiring pattern (15a) drawn out to the terminal 12a overlaps the portion exposed in the recess C2 of the insulating substrate in a plan view.

  According to the said structure, the influence of the noise from the mounting terminal 12a for power supplies can be reduced more. Of the wiring pattern 15a drawn from the oscillation circuit element mounting pad 11a to the power supply mounting terminal 12a, the portion exposed to the recess C2 of the insulating substrate is propagated from the power supply mounting terminal 12a because the upper part is released. Noise tends to diffuse upward. In the configuration according to the present embodiment, since the shielding electrode 8a of the crystal resonator is superimposed on the portion exposed to the recess C2 of the wiring pattern 15a, the influence of noise from the power supply mounting terminal 12a is affected. It can be further reduced.

  In the present embodiment, in a state where the oscillation circuit element 13 is mounted on the oscillation circuit element mounting pad 11 (11a to 11f), the oscillation circuit element mounting pad 11 is seen in plan view as shown in FIG. As a result, all of them are covered. The present invention is not limited to this configuration, and in a state after the oscillation circuit element is mounted, a part of the oscillation circuit element mounting pad may protrude outward from the oscillation circuit element in plan view. In the case of this configuration, the other of the pair of shielding electrodes of the crystal resonator covers the portion of the oscillation circuit element mounting pad connected to the power supply mounting terminal that protrudes outward from the oscillation circuit element in a plan view. What is necessary is just to position. Thereby, in addition to the portion exposed to the recess of the insulating substrate of the wiring pattern drawn out to the power supply mounting terminal, the protruding portion of the oscillation circuit element mounting pad can be shielded by the shielding electrode. Therefore, the influence of noise from the power supply mounting terminal can be further reduced.

  In the present embodiment, as shown in FIG. 6, the other (8a) of the pair of shield electrodes (8a, 8c) of the crystal resonator 2 is drawn from the oscillation circuit element mounting pad 11a to the power supply mounting terminal 12a. In the wiring pattern 15a, a part of the region covered with the side wall (31) of the insulating substrate is overlapped in a plan view.

  According to the said structure, the influence of the noise from the mounting terminal 12a for power supplies can be reduced more. This is because the other (8a) of the pair of shield electrodes (8a, 8c) of the crystal unit 2 is covered by the side wall (31) of the insulating substrate of the wiring pattern 15a drawn to the power supply mounting terminal 12a. This is because most of the region is overlapped in plan view, and thus the influence of noise not only from the power supply mounting terminal 12a but also from the region covered by the side wall of the wiring pattern 15a can be suppressed. .

  Further, in the present embodiment, as shown in FIG. 7, the power supply mounting terminal 12 a is configured not to overlap with the mounting electrode 6 of the crystal resonator 2 in plan view transmission. According to the said structure, the influence of the noise from the mounting terminal 12a for power supplies can be reduced more. This is because the ground layer is formed above the power supply mounting terminal 12a, so that not only the noise from the power supply mounting terminal 12a can be blocked by the ground layer, but also the power supply mounting terminal 12a can be transmitted through a crystal in plan view. This is because the influence of noise from the power supply mounting terminal 12a can be further reduced by arranging the vibrator 2 so as not to overlap the mounting electrode 6 of the vibrator 2.

  In the above-described embodiment of the present invention, the opening surface side of the concave portion of the insulating substrate is conductively bonded to the outer bottom surface side of the piezoelectric vibrator. However, the present invention is not applied only to the structure. For example, the structure may be such that the flat surface side opposite to the opening surface side of the concave portion of the insulating substrate is conductively bonded to the outer bottom surface side of the piezoelectric vibrator. In the case of such a structure, the bonding electrode in the above-described embodiment can be formed on the flat surface side of the insulating substrate, and the mounting terminal can be formed on the upper surface (top surface) side of the side wall.

-Modification of the embodiment of the present invention-
Another modification of the embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a schematic top view of an insulating substrate according to a modification of the embodiment of the present invention. A plurality of oscillation circuit element mounting pads formed on the inner bottom surface 161 of the recess C3 and wirings drawn from these pads. The description of the pattern is omitted. FIG. 9 is a partial cross-sectional view of a crystal oscillator according to a modification of the embodiment of the present invention, focusing on the mounting terminal 18a which is a power supply terminal. Hereinafter, differences from the embodiment of the present invention will be described. In addition, about the same structure as embodiment of this invention mentioned above, the same number is attached | subjected and the description is omitted.

  In the modification of the embodiment of the present invention, the configuration of the insulating substrate is different from the above-described embodiment of the present invention. Specifically, as shown in FIG. 8, the four corners of the outer peripheral edge of the insulating substrate 16 are perpendicular to each other in plan view, and the above-described castellations (33a to 33d) are not formed. Thus, since the castellation is not formed on the insulating substrate, the rigidity of the container body can be improved as compared with the container in which the castellation is formed. Furthermore, since the area of the upper surface (160) of the side wall surrounding the recess C3 of the insulating substrate can be ensured larger, the region where the bonding electrode can be arranged can be enlarged. That is, according to the insulating substrate according to the modification of the embodiment of the present invention, it is possible to expand the region where the bonding electrode can be arranged while increasing the rigidity of the container, and thus when the piezoelectric oscillator is further downsized. Is preferred.

  Four junction electrodes 17a, 17b, 17c, and 17d are formed at the four corners of the upper surface 160 of the sidewall of the insulating substrate 16. These bonding electrodes have a one-to-one correspondence with the four bottom electrodes 8a, 8b, 8c, and 8d of the crystal unit 2. That is, the bonding electrode 17a corresponds to the bottom electrode 8a, the bonding electrode 17b corresponds to the bottom electrode 8b, the bonding electrode 17c corresponds to the bottom electrode 8c, and the bonding electrode 17d corresponds to the bottom electrode 8d.

  The bonding electrode 17 (17a to 17d) has a shape bent in a substantially “L” shape in plan view, but a part of the configuration is different from the embodiment of the present invention. Specifically, the inner peripheral edge of the bonding electrode 17 is formed along the inner peripheral edge of the two adjacent side walls of the insulating substrate 16, but exceeds the inner peripheral edge of the two adjacent side walls. It extends to each inner wall surface continuing to the periphery (see FIG. 9). That is, the bonding electrode 17 in the modification of the present embodiment is formed from the upper surface of two adjacent side walls of the insulating substrate 16 to the lower end (inner bottom surface 161) of each inner wall surface of the two adjacent side walls. Note that the bonding electrode may have a configuration that does not extend from the upper surface of two adjacent side walls of the insulating substrate to the lower end of each inner wall surface of the two adjacent side walls. That is, the bonding electrode may be formed up to a height in the middle of each inner wall surface of the two adjacent side walls of the insulating substrate.

  On the other hand, among the outer peripheral edges of the bonding electrodes 17a to 17d, each corner that is closest to the four corners of the outer peripheral edge of the insulating substrate 16 is a right angle. As a result, the bonding electrodes 17 a to 17 d are formed to extend to the vicinity of the four corners of the outer peripheral edge of the insulating substrate 16. As a result, the bonding electrode 17 in the modified example of the present embodiment has a larger area in plan view than the bonding electrode 10 in the above-described embodiment of the present invention.

  The lower surface of the insulating substrate 16 (outer bottom surface of the crystal oscillator) is substantially rectangular in plan view, and mounting terminals 18 (18a, 18b, 18c, 18d) that are joined to the external substrate via solder or the like are formed at the four corners. (Only 18a is shown in FIG. 9). The mounting terminal 18a is a power supply terminal (DC), the mounting terminal 18b is for output, the mounting terminal 18c is for grounding, and the mounting terminal 18d is for frequency control (or ground).

  In the modification of the embodiment of the present invention, the bottom electrode 8a which is a shield electrode of the crystal resonator 2 is conductively bonded to the bonding electrode 17a of the insulating substrate. As a result, the bottom electrode 8a and the bonding electrode 17a bonded to the electrode have a ground potential. The bonding electrode 17a is located above the mounting electrode 18a which is a power supply terminal. With such a configuration, since the ground layer is formed above the power supply mounting terminal 18a, noise from the power supply mounting terminal 18a can be blocked by the ground layer. Here, as described above, since the area of the bonding electrode 17a in plan view is larger than that of the bonding electrode 10a in the embodiment of the present invention, the bonding electrode 17a overlaps with the mounting terminal 18a, which is a power supply terminal, in plan view. The area is also relatively large. Thereby, the influence of the noise from the mounting terminal 18a for power supplies can be reduced more.

  Furthermore, in the modification of the embodiment of the present invention, the bonding electrode 17a extending to each inner wall surface of the two adjacent side walls of the insulating substrate 16 is formed. With such a configuration, it is possible to suppress the noise transmitted from the power supply mounting terminal 18a from propagating to the recess C3 side. With the above configuration, since the influence of noise from the mounting terminal 18a can be further reduced, the phase noise characteristics of the crystal oscillator can be further improved.

  Since the bonding electrode 17 extends to the inner wall surface of the side wall of the insulating substrate 16, the fillet F of the bonding material 14 extends from the inner peripheral edge of the bottom electrode 8 to the boundary portion between the bonding electrode 17 and the upper surface of the underfill R. Will be formed. Accordingly, it is possible to improve the bonding strength on the concave portion C3 side while reducing the influence of noise from the mounting terminal 18a. The bonding electrode described above may extend from the upper surface of the side wall of the insulating substrate to a part of the pad for mounting the oscillation circuit element via the inner wall surface of the side wall. In the case of this configuration, in order to prevent insulation failure in the manufacturing process, electrode portions exposed on the inner wall surface of the side wall or the inner bottom surface 161 of the recess C3 may be covered with an insulating material such as alumina.

  In the embodiments of the present invention and modifications thereof, a temperature compensated crystal oscillator (TCXO: Temperature Compensated Oscillator) is taken as an example of a piezoelectric oscillator. The present invention can also be applied to the above.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted 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.

  It can be applied to mass production of piezoelectric oscillators.

DESCRIPTION OF SYMBOLS 1 Crystal oscillator 2 Crystal oscillator 3, 16 Insulating substrate 4 Container 6 Mounting electrode 7 Crystal element 8a-8d Bottom electrode 10a-10d, 17a-17d Bonding electrode 11a-11f Oscillator circuit element mounting pad 12a-12d, 18a-18d Mounting terminals 15a to 15d Wiring pattern

Claims (4)

A piezoelectric oscillator in which an insulating substrate containing an oscillation circuit element is bonded to the outer bottom surface of a piezoelectric vibrator,
The piezoelectric vibrator includes a piezoelectric element, a container that houses the piezoelectric element, and a metal lid, and a pair of bottom electrodes that are electrically connected to the piezoelectric element are provided on an outer bottom surface of the container. ,
A pair of bottom electrodes for shielding that are not electrically connected to the piezoelectric element and electrically connected to the lid;
The insulating substrate is electrically connected to a plurality of oscillation circuit element mounting pads, a plurality of mounting terminals drawn from the pads, and a part of the plurality of oscillation circuit element mounting pads, and corresponds to the bottom electrode. A bonded electrode,
The plurality of mounting terminals include a power supply mounting terminal and a ground mounting terminal,
Of the pair of bottom electrodes for shielding,
One is electrically connected to the ground mounting terminal,
The other of the piezoelectric oscillators is located above the power supply mounting terminal and is electromechanically bonded to a bonding electrode that is not electrically connected to the oscillation circuit element mounting pad.   The mounting electrode on which the piezoelectric element is mounted is formed on the container of the piezoelectric vibrator, and at least a part of the mounting electrode is overlapped with the bottom electrode for shielding in a plan view transmission. A piezoelectric oscillator according to 1.   The insulating substrate includes a recess in which an oscillation circuit element is accommodated, and the plurality of oscillation circuit element mounting pads on the inner bottom surface of the recess, and the other of the bottom electrodes for the pair of shields of the piezoelectric vibrator, 2. The wiring pattern drawn out from the oscillation circuit element mounting pad to the power supply mounting terminal is overlapped in a plan view with a portion exposed in the concave portion of the insulating substrate. Item 3. The piezoelectric oscillator according to Item 2.   4. The piezoelectric oscillator according to claim 1, wherein a mounting terminal for power supply of the insulating substrate does not overlap with a mounting electrode of the piezoelectric vibrator in a plan view. 5.

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