JP4938308B2 - Lame mode quartz crystal holding structure - Google Patents

Description

  The present invention relates to a resonator shape of a lame mode crystal resonator, and in particular, to improve a device mounting structure for realizing miniaturization and high accuracy while maintaining the electrical characteristics of the device. The present invention relates to an element shape and a container structure of a lame mode crystal resonator that has improved holding strength and simplification during mounting against dropping and impact.

  The lame mode vibrator is small and can obtain an optimum vibration mode for realizing a low frequency. Therefore, the realization of miniaturization while being a low-frequency vibrator has a large market widely used in mobile phones, portable small game devices and the like that have made remarkable progress in recent years.

The lame mode vibrator is formed of a piezoelectric substrate with a thickness of several tens of μm. In order to hold the lame mode vibrator, a vibration node with a rotational moment but no displacement is used so as not to hinder vibration. It is common to hold. As shown in FIG. 6 , it is supported and held through the connecting portions at the four corners. From this node, the arm is pulled out and connected to the holding portion, and mounted on the package via the connecting portion and assembled to obtain a vibrator. At this time, by making the arm portion as thin as possible, the inhibition of vibration can be reduced and the equivalent series resistance can be reduced. Therefore, a strong structure is required at the time of drop impact.

  In short, conventionally, when a vibrator is manufactured, support portions are provided at the four corners of a square serving as a node of vibration in order to avoid an increase in the equivalent resistance value R1, and accordingly, the vibration portion, the support portion, Since the connecting portions are integrally formed, moment forces are generated at the four corners that are vibration nodes. Therefore, if the design of the support portion is not appropriate, vibration energy leaks to the support portion, and the equivalent resistance value R1 increases. Furthermore, in order to reduce the equivalent resistance value R1, in order to reduce the increase in the equivalent resistance value R1, if the width and thickness of the support part from the four corners are reduced, it may be affected by an impact such as dropping or an excessive excitation current. There is a risk of damage if the amplitude increases.

  As described above, when the lame mode crystal resonator is a square plate, it is a vibration mode in which the four corners are nodes (rotation nodes) and vibrate in the same volume in the plane. In order to obtain a vibrator having a good (low) equivalent resistance value R1, it is the most effective support method to pull out the support portions from the four corners which are the nodes of vibration. The actual support method is as follows. At present, it is fixed to a substrate such as ceramic using a conductive adhesive via a connecting portion.

An example of the above-described process is shown in FIG. 7. A series of wafer cleaning, light etching, protective vapor deposition film (CrAu), resist coating, exposure, development, patterning, etching, resist stripping, CrAu stripping, cleaning, excitation electrode deposition An element is formed in the process and is mounted on a package made of a ceramic material or the like with a conductive adhesive to obtain a lame mode vibrator.

JP 2003-142979 A JP 2001-31537 A JP 2004-242256 A JP, 2005-244702, A In addition to the prior art literature specified by the above-mentioned prior art literature information, the applicant did not find the prior art literature relevant to the present invention by the time of this application.

  Since the conventional lame mode quartz crystal resonator described above is a rectangular plate with an integer ratio of the vibration part, for example, when supporting the four corners of the vibration part, the vibration nodes are the four corners and the vibration displacement is small. The vibration of the lame mode due to the holding of the vibration part is not hindered.

  However, since the vibration part, the support part, and the connection part are integrally formed, when the piezoelectric element for the lame mode crystal resonator is mounted and stored in the container, the vibration part and the support part are connected to each other. Since a rotational moment force generated from the displacement of the lame mode vibration is generated, bending vibration is generated at the connection portion under the influence of the moment force.

  Therefore, if the shape of the support part and the connection part is not set to appropriate design values, vibration of the vibration part will occur, and unnecessary vibration will be transmitted to the support part and connection part that hold the vibration part. There is a risk that the vibrations of the

  In addition, in order to mount the vibrating part on the container by some means, a support part and a connection part are required. For this reason, when considered in the form of a vibrator, a structure in which a support part and a connection part are integrated in addition to the vibration part is required, so that it is difficult to reduce the overall size.

  On the other hand, in order to promote downsizing, the support part other than the vibration part is made lighter and made fragile, so there is a risk of insufficient strength against dropping and impact due to the structure of the conventional lame mode vibrator. Conceivable.

As an example of the above-described mounting, in the conventional manufacturing process of the lame mode vibrator, as shown in FIG. 8A in which the BB cross-section of FIG. 8 is enlarged, it is interposed between the element and the package. If only the bonding member (conductive adhesive) is mounted, the element can be fixed and conducted only by adhesion of the lower electrode.

In addition, as shown in FIG. 8B , a protection film (CrAu film) used in a manufacturing process for forming an element is used for an excitation electrode to simplify the process, but the electrode cannot be formed on the side surface of the element. For this reason, since the lower electrode and the upper electrode cannot conduct on the side surfaces, it is difficult to sufficiently fix and conduct the element. This is because the entire outer shape of the device is formed by etching treatment, so that the device outer shape is perpendicular to the thickness direction, that is, from the lower side to the upper side of the device, and CrAu used for the protective film. There is a problem that the conductive adhesive does not effectively adhere to the film, and the connection with the lead electrode on the upper part of the element cannot be sufficiently performed.

Therefore, in order to improve the above-described problem, the present invention is a short circuit when a charge is applied to a rectangular piezoelectric element and the piezoelectric element extends in the longitudinal direction of the rectangular shape with four corners of the piezoelectric element as nodes. contraction in the direction, and the resulting vibration form of contour vibration shrinks in the longitudinal direction when extending the rectangular lateral direction, LQ1T cut or the holding structure of the Lame mode quartz resonator consisting of quartz substrate LQ2T cut, A holding part in which a convex part is formed integrally with the piezoelectric element in a non-displacement part having no rotational moment in the vibration area of the piezoelectric element, an excitation electrode formed in the vibration area of the piezoelectric element, and the holding part. A container body having a concave structure that holds the piezoelectric element in a form that fits with a certain convex portion, and a lead electrode is formed on the surface of the holding portion and connected to the excitation electrode, and is guided to the concave portion. Metal film is provided, a retaining structure Lame mode quartz crystal resonator, characterized in that said recess structure is retained and electrically connected to the fixing in a form matching the holder.

  Specifically, a container having a concave structure that holds the piezoelectric element in a form in which a convex part is formed in a non-displacement part having no rotational moment within the vibration region of the piezoelectric element and is fitted to the convex part. A part of the extraction electrode from the excitation electrode formed on the piezoelectric element is formed on the holding portion, and the holding portion is electrically connected simultaneously with the mounting of the container body. It is a holding structure of a mode crystal resonator.

  Based on the above, in order to promote downsizing of the element, which has been cited as a conventional problem, the supporting part other than the vibration part is reduced in weight, and the lack of strength against dropping and impact caused by making it fragile is improved. Furthermore, the entire lame mode vibrator can be made compact by processing the soft bonding metal in the holding part to form an electrical connection structure so that the piezoelectric element can be mounted on the container body and at the same time the electrical connection can be realized. Therefore, it is possible to improve the impact resistance and simplify the mounting of the piezoelectric element on the container.

  As described above, the present invention uses the etching solution in the manufacturing method of the lame mode crystal resonator, and the LQ1T cut or LQ2T cut crystal substrate forms the element outline by the processing method by wet etching and at the same time within the vibration region of the piezoelectric element. By forming and supporting the holding part in the non-displaced part with no rotational moment, and supporting the holding part without displacement and rotational moment at the center of gravity of each vibration region, the support becomes point contact and piezoelectric By reducing the restraining force on the element, the mounting strength of the element, which increases the mechanical strength against dropping and impact, is ensured, and fluctuations in electrical characteristics at the time of dropping impact are reduced. As a result, by improving the impact resistance, it is possible to improve the quality of the lame mode vibrator, improve the manufacturing yield, and simplify the manufacturing process.

Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same numerals indicate the same objects.
A piezoelectric element 1 having a piezoelectric element substrate as a substrate, where one dimension of the side ratio of the substrate is 1 (L), and the other dimension is an infinite number of plates satisfying an integer ratio (1 (L) to n) The vibration mode existing in is called a lame mode resonator. In the case of a square plate as shown in FIG. 1, when the two sides A facing each other with the corners at the four corners are displaced toward the center of the square, the other two sides B are displaced outwardly of the square, and the two sides facing each other When A is displaced in the outward direction of the square, the other two sides B are in a vibration form that is displaced in the center direction of the square.

  Therefore, it vibrates in the form of repeating the operations of FIG. 1A and FIG. This FIG. 1 is called the lowest order vibration mode of a square plate. FIG. 1C shows a dimensional concept of the diaphragm. FIG. 2 shows a schematic diagram of the vibration mode. FIG. 3 shows an example of a high-order vibration mode based on the basic shape. The idea is the same as the basic form of FIG. 1, FIG. 3 (a) shows the secondary case, and FIG. 3 (b) shows the tertiary case. 1 and 3 indicate a non-vibrating portion of the lame mode vibrator.

  Now, as a feature of the present invention, a perspective view shown in FIG. 4 will be described as an example. Features a holding part 3 formed in a non-displacement part 2 (hereinafter referred to as a non-displacement part) having no rotational moment of an element having a higher-order vibration form, and a structure for holding the piezoelectric element 1 in a form matching the holding part 3 This is a lame mode crystal resonator. At this time, the center of gravity of the vibration region of the primary form of the lame mode vibrator is held, and even in the case of a higher order, the center of gravity of each vibration region is held.

  Concerning the holding part 3, a convex part is formed integrally with the element on the non-displaceable part 2 in the vibration region of the piezoelectric element 1, and a concave part (receiver 4) that holds the piezoelectric element 1 in a form that fits the convex part. It becomes a form mounted in the container body 7 which has a structure.

FIG. 5 is a drawing of section AA of FIG. 4, and FIG. 5 (a) shows the section. 5A is an enlarged view of the main part shown in FIG. 5A, and FIG. 5B is a enlarged view of the holding part formed in the non-displacement part 2 in the vibration region of the lame mode crystal resonator. 3, a lead electrode is formed and connected to the excitation electrode so that the lead 4 of the container body 7 fitted to the holding portion 3 can be electrically connected to the lead electrode 6 of the piezoelectric element 1. is formed, by being conductive metallic film 4 parts receiving is provided Rukoto, the holding unit 3 realizes the continuity and the fixing of the piezoelectric element 1. FIG. 5B shows a form in which the piezoelectric element 1 and the receiving portion 4 of the container body 7 are engaged with each other. FIG. 5C shows a simplified structure by providing a recess in the container body 7. The excitation electrode is formed in the vibration region of the piezoelectric element.

  In short, the holding part 3 on the piezoelectric element 1 side is formed into a cylindrical or conical shape, for example, conduction is made with an electrode metal such as Cr—Au, Ti—Au including the excitation electrode 5, and the conduction metal film is patterned from the receiver 4, A part of the conductive metal film is drawn out of the container body 7 via the glass embedded through conductor 10 and connected to the electrode terminal of the container body 7. Therefore, the container body 7 is arranged on the upper and lower sides (front and back) of the piezoelectric element 1 and has a structure in which the holding portion 3 is sealed in a form of fitting with the receiving portion 4 of the container body.

As described above, the holding part 3 formed in the non-displacement part 2 of the piezoelectric element 1 described above is appropriately arranged in a place where vibration (no displacement and no rotational moment) propagating from a so-called lame mode vibrator is zero. Yes, it is not related to size or shape. Further, in the piezoelectric element 1 in the case of higher order, the holding part 3 does not need to be held by all the non-displaceable parts 2 in the vibration region of the piezoelectric element 1, and the non-displaceable part 2 can be selected appropriately. good. In addition, the shape of the holding | maintenance part 3 and the receiving part 4 is not ask | required. Further, by applying aluminum, gold, copper, or solder material as the soft bonding metal 9 to the holding portion, contact between the container body 7 and the holding portion of the piezoelectric element 1 can be relaxed.

  As mentioned above, although it is the technique regarding mounting of the piezoelectric element 1 mentioned above, it does not ask the structure and material of the container body 1. FIG. However, since a wafer level sealing technique is required to realize a miniaturized container, it is conceivable in the future to use, for example, anodic bonding or direct bonding using a glass material. Of course, the use of ceramic materials or organic materials is also sufficient.

It is a top view which shows the primary form of a lamé mode crystal oscillator. This is a mode for analyzing the vibration form shown in FIG. It is a top view which shows the vibration form in the case of a higher order based on the basic form of FIG. It is a perspective view which shows the form of the lame mode vibrator | oscillator of this invention. It is the fragmentary sectional view which showed the state of the principal part of this invention. It is a conceptual diagram of the lame mode crystal resonator form shown as a conventional example. It is a flowchart which shows the manufacturing process which forms the element of a lame mode vibrator. It is a fragmentary sectional view which shows the mounting state of a prior art example.

Explanation of symbols

1 Piezoelectric element 2 Non-displacement part (non-displacement part without rotational moment)
DESCRIPTION OF SYMBOLS 3 Holding part 4 Receiving part 5 Excitation electrode 6 Lead electrode 7 Container body 8 Vibration area | region 9 Metal for soft joining

Claims (1)

When a charge is applied to the rectangular piezoelectric element, the corners of the four corners of the piezoelectric element are nodes, and when extending in the longitudinal direction of the rectangular shape, it contracts in the short direction, and the rectangular short direction In the holding structure of the lame mode quartz crystal resonator made of the LQ1T cut or LQ2T cut quartz substrate, which generates the vibration form of the contour vibration that shrinks in the longitudinal direction when extended to
A holding part in which a convex part is formed integrally with the piezoelectric element in a non-displaceable part without a rotational moment in the vibration region of the piezoelectric element;
An excitation electrode formed in a vibration region of the piezoelectric element;
A container body having a concave structure that holds the piezoelectric element in a form that fits with the convex part that is the holding part;
A lead electrode is formed on the surface of the holding portion and connected to the excitation electrode,
A conductive metal film is provided in the recess,
A holding structure for a lame mode crystal resonator, wherein the concave structure is held in a fixed state and in conduction in a form that matches the holding portion.

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