JP4645376B2 - Tuning fork type piezoelectric vibrator - Google Patents

Description

  The present invention relates to a tuning fork type piezoelectric vibrator, and more particularly to a package structure of a tuning fork type piezoelectric vibrator in which a tuning fork type crystal vibrating piece is bonded to a ceramic multilayer substrate using a conductive resin adhesive.

As one of the piezoelectric vibrating devices, as disclosed in Patent Document 1, a tuning fork type piezoelectric vibration using a tuning fork type piezoelectric vibrating piece including a base portion and a vibrating portion having two legs protruding from the base portion. There is a child. This tuning fork type piezoelectric vibrator is used in an electronic device, a portable terminal, or the like for obtaining an accurate clock frequency. The surface mount type tuning fork type piezoelectric vibrator has a package composed of a ceramic multilayer substrate and a lid. Inside the package, a tuning fork type piezoelectric resonator element bonded and held on the ceramic multilayer substrate is hermetically sealed. Stopped. For example, a conductive resin adhesive is used for the conductive bonding member of the tuning fork type piezoelectric vibrating piece to the ceramic multilayer substrate. With this conductive resin adhesive, the excitation electrode provided on the tuning fork type piezoelectric vibrating piece and the conductive pad provided on the ceramic multilayer substrate are brought into conduction.
Japanese Patent Laid-Open No. 2004-260718

  In a tuning fork type piezoelectric vibrator bonded to a ceramic multilayer substrate with a conductive resin adhesive, if the tuning fork type piezoelectric vibrating piece is excessively bent due to an external impact such as dropping after hermetic sealing, the tuning fork type piezoelectric vibration There has been a problem in that the frequency of the child is negatively changed and a desired frequency characteristic cannot be obtained. This is because the free end of the tuning fork type piezoelectric vibrating piece is greatly bent, and a large stress is applied to the conductive resin adhesive at the fixed end of the tuning fork type piezoelectric vibrating piece, and the tuning fork type piezoelectric vibrating piece and the conductive resin adhesive are applied. Alternatively, the molecular chain peels off at the adhesive interface between the conductive resin adhesive and the ceramic multilayer substrate, and the adhesive interface state of the conductive resin adhesive changes. As a result, the stress applied to the tuning fork type piezoelectric vibrating piece by the conductive resin adhesive changes, resulting in a slight leakage of vibration energy from the tuning fork type piezoelectric vibrating piece to the bonding region. In addition, even if the adhesion interface state of the conductive resin adhesive changes, the electromechanical bonding strength by the conductive resin adhesive is not affected.

  In order to solve the above problems, the present invention provides a more reliable tuning fork type piezoelectric vibrator capable of suppressing the frequency fluctuation of the tuning fork type piezoelectric vibrator due to a change in the adhesive interface of the conductive resin adhesive. With the goal.

  Therefore, a tuning fork type piezoelectric vibrator of the present invention comprises a tuning fork type piezoelectric vibrating piece having a base and a plurality of legs protruding from the base, a ceramic multilayer substrate, and a lid, and the tuning fork type piezoelectric vibrator. A tuning-fork type piezoelectric vibrator, wherein a base of a vibrating piece is held on the ceramic multilayer substrate by a conductive resin adhesive, and the ceramic multilayer substrate is covered with a lid and hermetically sealed. Is provided with an excitation electrode composed of different potentials and a lead-out electrode connected to the excitation electrode, and the tip of each leg main surface is made of a metal material, and the mass is reduced to reduce the frequency. The ceramic multilayer substrate is formed in the bottomed storage portion and in the storage portion, and is formed in parallel to mount the base of the tuning fork type piezoelectric vibrating piece. Two conductive pads and many ceramics A single ridge line portion that is wider than the frequency adjustment electrode and exposes the substrate of the ceramic multilayer substrate is provided at a position facing a part of the frequency adjustment electrode of the tuning fork type piezoelectric vibrating piece held on the substrate, and hermetically sealed. If the tuning fork type piezoelectric vibrating piece is greatly bent, the adhesive interface state of the conductive resin adhesive changes, and a negative fluctuation occurs in the frequency of the tuning fork type piezoelectric vibrator, the tuning fork type piezoelectric vibrating piece is greatly bent. The frequency adjustment electrode is in contact with the ridge line portion in synchronism, and a part of the frequency adjustment electrode is transferred to the ridge line portion, so that the frequency of the tuning fork type piezoelectric vibrator is adjusted to be positively changed. Features.

  In addition to the above configuration, the ceramic multilayer substrate includes a bank part surrounding the storage part and a bridge part that connects a part of the bank part, and the frequency adjustment electrode is in contact with a ridge line of the bridge part. The frequency of the tuning fork type piezoelectric vibrating piece is adjusted by transferring a part of the frequency adjusting electrode to the ridge line portion.

  Further, in addition to the above configuration, the frequency adjusting electrode is made of a metal material softer than ceramic.

  According to claim 1 of the present invention, the tuning fork-type piezoelectric vibrating piece is provided with an excitation electrode configured with a different potential and a lead-out electrode connected to the excitation electrode, and a tip of each leg main surface. The part is made of a metal material and is provided with a frequency adjustment electrode whose frequency is adjusted by reducing the mass, and the ceramic multilayer substrate is formed in the bottomed storage part and the storage part. The frequency adjustment is arranged at a position facing two conductive pads formed in parallel to mount the base of the tuning fork type piezoelectric vibrating piece and a part of the frequency adjusting electrode of the tuning fork type piezoelectric vibrating piece held on the ceramic multilayer substrate. A line of ridges that are wider than the electrodes and expose the substrate of the ceramic multilayer substrate are provided.

  For this reason, the tuning fork type piezoelectric vibrating piece hermetically sealed due to an impact such as dropping is greatly bent, the adhesive interface state of the conductive resin adhesive changes, and a negative fluctuation occurs in the frequency of the tuning fork type piezoelectric vibrator. In addition, the frequency adjustment electrode is in contact with the ridge line portion in synchronization with the large deflection of the tuning fork type piezoelectric vibrating piece, and a part of the frequency adjustment electrode is transferred to the ridge line portion. Is adjusted to fluctuate positively.

  On the other hand, if the tuning fork type piezoelectric vibrating piece that is hermetically sealed without applying an impact such as dropping does not bend greatly, the adhesive interface state of the conductive resin adhesive does not change, and the frequency of the tuning fork type piezoelectric vibrator is not changed. There will be no negative fluctuations. Further, since the frequency adjustment electrode of the tuning fork type piezoelectric vibrating piece does not contact the ridge line portion, the frequency of the tuning fork type piezoelectric vibrator is positively changed without transferring a part of the frequency adjustment electrode to the ridge line portion. It is not adjusted to do.

  In other words, only when a strong external impact such as dropping is applied, the negative frequency fluctuation caused by the change in the interface state of the conductive resin adhesive is caused by the transfer of the frequency adjustment electrode to the ceramic multilayer substrate. Since it is almost canceled by the plus fluctuation of the frequency generated by the reduction, the fluctuation of the frequency as the tuning fork type piezoelectric vibrator is suppressed. If a strong impact such as dropping is not applied, the frequency fluctuation itself does not occur, so the offset function is adjusted so that it does not work. At this time, since a single ridge is formed, the impact when the tuning fork type piezoelectric vibrating piece comes into contact is evenly distributed, and the influence of chipping of the tuning fork type piezoelectric vibrating piece can be reduced as much as possible.

  According to claim 2 of the present invention, in addition to the above-described effects, the ceramic multilayer substrate is formed with a bank part surrounding the storage part and a bridge part connecting the part of the bank part. The frequency adjustment electrode is in contact with the ridgeline of the portion, and a part of the frequency adjustment electrode is transferred to the ridgeline portion so that the frequency of the tuning fork type piezoelectric vibrating piece is adjusted. In addition to obtaining a single ridge line with exposed base material, mechanical bending strength at the embankment of the ceramic multilayer substrate, where thermal strain is concentrated during hermetic sealing, is reinforced to prevent cracking. It can be drastically suppressed.

  According to claim 3 of the present invention, in addition to the above-described effects, the frequency adjustment electrode is made of a metal material softer than ceramic, so that the transferability to a ridge line portion where the ceramic substrate is exposed is improved. It is possible to adjust so that the frequency adjusting electrode is more reliably reduced. In addition, the frequency adjustment electrode made of a metal material softer than ceramic can reduce the impact on the tuning fork type piezoelectric vibrating piece, thereby reducing the effect of chipping.

  An embodiment according to the present invention will be described with reference to FIGS. 1 to 3 by taking a surface-mounted tuning fork type crystal resonator as an example. FIG. 1 is a plan view showing an embodiment of the present invention, and shows a state in which a tuning fork type crystal vibrating piece (tuning fork type piezoelectric vibrating piece) is mounted on a storage portion. FIG. 2 is a cross-sectional view taken along the line AA in the state in which the cover is applied to FIG. FIG. 3 is a plan view before the tuning-fork type crystal vibrating piece of FIG. 1 is mounted.

  The surface-mounted tuning-fork type crystal resonator has a rectangular parallelepiped shape as a whole, and is housed in the ceramic multilayer substrate 1 having a concave housing portion 1a having an open top and a substantially rectangular shape in plan view. It consists of a crystal vibrating piece 2 that is an element of a piezoelectric vibrating device, and a metal lid 3 that is bonded to the opening of the package.

  The tuning-fork type crystal vibrating piece 2 housed in the ceramic multilayer substrate 1 includes an excitation electrode (not shown) formed on each leg, lead-out electrodes 21 and 22 from each excitation electrode formed on the base, and each leg. Frequency adjusting electrodes 23 and 24 are formed at the tip of the main part surface. These electrodes are made of a metal material such as chromium, gold, or silver, and the frequency adjustment electrodes 23 and 24 are formed of a metal material whose uppermost layer is softer than a ceramic such as gold or silver. The frequency adjustment electrodes 23 and 24 are adjusted to a desired frequency as a tuning fork type crystal resonator by reducing the mass of the electrodes by a method such as laser beam or milling.

  When viewed in cross section, the ceramic multilayer substrate 1 is concave, and has a substantially rectangular shape in plan view, and has a bottomed storage portion 1a and a tuning fork crystal resonator element formed on the bottom of the storage portion. It has the part 1b, 1c, and the bank part (side wall) 10 surrounding the said accommodating part and a step part.

  Conductive pads 12 and 13 are formed in parallel with each other on the upper surface of each step portion, and a circumferential sealing metallization portion 11 is formed on the upper surface of the bank portion 10. The conductive pads 12 and 13 and the sealing metallized portion 11 are formed using a lamination technique, and are composed of a metallized layer made of tungsten or the like and a metal film layer formed on the metallized layer. The metal film layer is composed of, for example, a nickel plating layer in contact with the metallized layer and an ultrathin gold plating layer formed on the nickel plating layer.

  A rectangular and insulating bridge portion 1d that connects a part of the bank portion 10 in the short side direction is formed at the central portion in the long side direction of the ceramic multilayer substrate. As shown in FIG. 1, if this bridging portion 1d is formed so as to partially overlap the central line BB in the long side direction of the ceramic multilayer substrate, the mechanical bending strength is reinforced, The generation of cracks can be drastically suppressed. In addition, the bridge | crosslinking part 1d of this form is comprised with the same ceramic layer as the said step parts 1b and 1c.

  A first recess 1e is formed between the step portions 1b, 1c of the ceramic multilayer substrate 1 and the bridging portion 1d, and a second portion is formed between the step portions 1b, 1c of the ceramic multilayer substrate 1. The recess 1f is formed. A third concave portion 1g lower than the bridging portion 1d is formed at a portion corresponding to the tip portion of the leg portion which is a free end of the quartz crystal resonator element of the ceramic multilayer substrate 1. Due to the step formed by the bridging portion 1d and the third concave portion 1g, a single ridge line portion 11d that is wider than the frequency adjusting electrodes 23 and 24 and exposes the substrate of the ceramic multilayer substrate is provided. The one ridge line portion 11d is formed along the arrangement direction of the leg portions, and as will be described later, the tuning fork type piezoelectric vibrating piece 2 held on the ceramic multilayer substrate 1 by a conductive resin adhesive. It is formed at a position facing a part of the frequency adjustment electrodes 23, 24.

  Chamfered portions R1 to R12 of curvature are formed at the corners of the storage portion 1a and the recesses 1e to 1g, the connecting portion between the bank portion and the bridge portion, and the connecting portion between the bank portion and the step portion, respectively. Yes. In this embodiment, for example, the short side dimension of the ceramic multilayer substrate 1 is 1.5 mm and the long side dimension is 3.2 mm, which is set to 1.5 times or more.

  Then, the lead-out electrodes 21 and 22 of the crystal vibrating piece 2 and the conductive pads 12 and 13 are electrically and mechanically bonded by the conductive bonding material D. As the conductive bonding material D, for example, a silicone resin adhesive with a metal filler interposed is used. At this time, the base side of the crystal vibrating piece 2 is fixed to the upper surfaces of the conductive pads 12 and 13 through the conductive bonding material D, and is held on one side with the leg side of the crystal vibrating piece 2 being a free end.

  Further, the metal lid 3 is mounted on the metallizing portion 11 for sealing, and in this state, the metal lid and the metallizing portion for sealing are melted by a seam roller (not shown) and hermetically sealed.

  According to the present invention, the tuning fork type piezoelectric vibrating piece 2 hermetically sealed due to an impact such as dropping is greatly bent, and the bonding interface state of the conductive resin adhesive D changes, and the frequency of the tuning fork type piezoelectric vibrator is negatively affected. Even if the fluctuation occurs, the frequency adjustment electrodes 23 and 24 abut against the ridge line portion 11d in synchronization with the large bending of the tuning fork type piezoelectric vibrating piece 2, and a part of the frequency adjustment electrodes 23 and 24 is ridge line portion 11d. The frequency of the tuning fork type piezoelectric vibrator is adjusted so as to change positively. On the other hand, if the tuning fork type piezoelectric vibrating piece 2 that is hermetically sealed without being subjected to an impact such as dropping is not greatly bent, the bonding interface state of the conductive resin adhesive D does not change, and the tuning fork type piezoelectric vibrator is not changed. There is no negative fluctuation in the frequency. Further, since the frequency adjustment electrodes 23 and 24 of the tuning fork type piezoelectric vibrating piece 2 do not come into contact with the ridge line portion 11d, a part of the frequency adjustment electrodes 23 and 24 is not transferred to the ridge line portion 11d. The frequency of the piezoelectric transducer is not adjusted so as to fluctuate positively. That is, only when a strong external impact such as a drop is applied, the negative fluctuation of the frequency caused by the change in the interface state of the conductive resin adhesive D is the transfer of the frequency adjusting electrodes 23 and 24 to the ceramic multilayer substrate 1. Therefore, the frequency fluctuation as the tuning fork type piezoelectric vibrator is suppressed because the frequency adjustment electrodes 23 and 24 substantially cancel each other by the plus fluctuation of the frequency. If a strong impact such as dropping is not applied, the frequency fluctuation itself does not occur, so the offset function is adjusted so that it does not work. At this time, since the single ridge portion 11d is used, the impact when the tuning fork type piezoelectric vibrating piece 2 comes into contact is evenly distributed, and the influence of chipping of the tuning fork type piezoelectric vibrating piece 2 can be reduced as much as possible.

  The bridge portion 1d not only provides a single ridge line portion where the substrate of the ceramic substrate for frequency adjustment electrode transfer is exposed, but also a bank portion of the ceramic multilayer substrate where thermal strain is concentrated when hermetically sealing is performed. The mechanical bending strength at 10 is reinforced, and the generation of cracks can be remarkably suppressed.

  Further, since the frequency adjusting electrodes 23 and 24 made of a metal material softer than a ceramic such as gold or silver are formed, the transferability to the one ridge line portion 11d where the ceramic base is exposed is improved, and more reliably. Not only can the frequency adjustment electrodes 23 and 24 be adjusted to be reduced, but gold having a high specific gravity is more preferable as the adjustment electrode. Further, the frequency adjusting electrodes 23 and 24 made of a metal material softer than a ceramic such as gold or silver can reduce the impact on the tuning fork type piezoelectric vibrating piece 2 and further reduce the influence of chipping.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. For example, the conductive bonding material is not limited to a silicone-based resin adhesive, and other resin adhesives may be used. The adjustment electrode is exemplified by gold or silver, but copper may be used. Further, the chamfer is not limited to a curved shape. In the above description, the bridge portion connecting a part of the bank portion of the ceramic multilayer substrate is taken as an example of the one ridge line portion, but a pillow material larger than the width of the leg portion of the tuning fork type piezoelectric vibrating piece may be used. In addition, seam welding is used as an example of the sealing method, but sealing by beam welding such as laser or electron beam may be used, and glass sealing or resin sealing may be used using a ceramic material as a lid. Good. 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.

The top view in the state where the crystal vibrating piece which shows the embodiment of the present invention was carried. Sectional drawing along the AA line of FIG. FIG. 2 is a plan view before mounting the crystal resonator element of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic multilayer substrate 10 Bank part 11 Metallizing part for sealing 2 Tuning fork type crystal vibrating piece (Tuning fork type piezoelectric vibrating piece)
12, 13 Conductive pad 3 Metal lid (metal lid)

Claims (3)

A tuning fork-type piezoelectric vibrating piece comprising a base and a plurality of legs protruding from the base, a ceramic multilayer substrate, and a lid are provided. The base of the tuning-fork type piezoelectric vibrating piece is made of ceramic by a conductive resin adhesive. A tuning fork type piezoelectric vibrator that is hermetically sealed by covering a ceramic multilayer substrate with a lid held on the multilayer substrate,
The tuning-fork type piezoelectric vibrating piece is provided with an excitation electrode configured with a different potential and a lead-out electrode connected to the excitation electrode, and a tip portion of each leg main surface is made of a metal material and has a mass. A frequency adjustment electrode is provided in which the frequency is adjusted by being reduced,
The ceramic multilayer substrate includes a bottomed storage portion, two conductive pads formed in parallel in the storage portion and mounting the base of the tuning fork type piezoelectric vibrating piece, and a tuning fork held by the ceramic multilayer substrate. In a position facing a part of the frequency adjustment electrode of the type piezoelectric vibrating piece, there is provided a single ridge line portion that is wider than the frequency adjustment electrode and from which the substrate of the ceramic multilayer substrate is exposed,
When the tuning fork type piezoelectric vibrating piece that is hermetically sealed is greatly bent, the adhesive interface state of the conductive resin adhesive changes, and a negative fluctuation occurs in the frequency of the tuning fork type piezoelectric vibrator.
In synchronization with the large deflection of the tuning fork type piezoelectric vibrating piece, the frequency adjustment electrode contacts the ridge line portion, and a part of the frequency adjustment electrode is transferred to the ridge line portion, thereby increasing the frequency of the tuning fork type piezoelectric vibrator. A tuning fork type piezoelectric vibrator characterized by being adjusted so as to fluctuate. The ceramic multilayer substrate is formed with a bank part surrounding the storage part and a bridge part connecting the part of the bank part, and the frequency adjustment electrode is in contact with a ridge line of the bridge part, and a part of the frequency adjustment electrode 2. The tuning fork type piezoelectric vibrator according to claim 1, wherein the frequency of the tuning fork type piezoelectric vibrating piece is adjusted by being transferred to the ridge line portion. 3. The tuning fork type piezoelectric vibrator according to claim 1, wherein the frequency adjusting electrode is made of a metal material softer than ceramic.

Images