JP2007158458A - Lame-mode quartz crystal resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape of a Lame-mode quartz crystal resonator, in particular, to obtain a shape of a piezoelectric element for improving a mount state of the piezoelectric element for achieving downsizing and high accuracy and enhancing the mount strength against a fall and a shock while maintaining the electric characteristic of the piezoelectric element. <P>SOLUTION: The Lame-mode quartz crystal resonator comprises a crystal substrate of the LQ1T-cut or the LQ2T-cut causing a vibration mode of contour vibration in which the crystal substrate is contracted in a short side direction when the crystal substrate is elongated in the long side direction of a rectangle and the crystal substrate is contracted in the long side direction when the crystal substrate is elongated in the short direction of the rectangle by using four corner points of the piezoelectric element for nodes in the case that electric charges are applied to the rectangular piezoelectric element comprising a vibration part, a support part, and a connection part in order to solve the above problem. In the Lame-mode quartz crystal resonator, a hole through which the element is inserted is provided in the support part and the element is mounted by impregnating a support member to the hole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resonator shape of a lame mode crystal resonator, and in particular, to improve the mounting state of an element for realizing miniaturization and high accuracy while maintaining the electrical characteristics of the element. The present invention relates to an element shape with improved mounting strength 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 for 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 having a thickness of several tens of μm. In order to hold the lame mode vibrator, it is common to hold a vibration node so as not to hinder vibration. . As shown in FIG. 7, 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 support portion is not properly designed, vibration energy leaks to the support portion and the equivalent resistance value R1 becomes large. Further, 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 2 from the four corners are reduced, an impact such as dropping or excessive excitation current may occur. There is a risk of damage when the amplitude increases due to the above.

  As described above, when the lame mode crystal resonator is a square plate, the conventional lame mode crystal resonator has an equivalent resistance value R1 because it is a vibration mode in which four corners become nodes and vibrate in the same volume in a plane. To obtain a good (low) vibrator, the most effective support method is to pull out the support parts from the four corners that are the nodes of vibration. For the actual support method, the support part of the vibrator is connected to the connection part. At present, it is fixed to a substrate such as ceramic using a conductive adhesive.

  An example of the above-described process is shown in FIG. 8. 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 lame mode crystal resonator is mounted and stored in the container, the part that connects the vibration part and the support part has a lame mode vibration. Since the moment force generated from this node is generated, bending vibration is generated in 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 has a fragile shape, so there is a possibility that the structure of the conventional lame mode vibrator may be insufficient in strength against dropping or impact. .

  As an example of the above-described mounting, in the conventional manufacturing process of the lame mode vibrator, as shown in FIG. 9A in which the BB cross section of FIG. 7 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. 9B, a protection film (CrAu film) used in a manufacturing process for forming an element is used as an excitation electrode to simplify the process. However, an 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 element is formed by etching treatment, so that only the (crystal) element is formed in the thickness direction that is the side of the element, that is, from the lower part to the upper part of the element, and metal for conduction cannot be formed. Thus, only the CrAu film on the upper and lower surfaces of the element used for the protection film does not effectively adhere the conductive adhesive, and there is a problem that the connection with the lead electrode on the upper part of the element cannot be performed sufficiently.

  Therefore, in order to improve the above-described problems, the present invention has four corners of the piezoelectric element as nodes when a charge is applied to a rectangular piezoelectric element (element plate) including a vibration part, a support part, and a connection part. An LQ1T cut or an LQ2T cut that generates a vibration form of contour vibration that expands and contracts in the short direction when extending in the longitudinal direction of the rectangular shape and expands and contracts in the longitudinal direction when extending in the short direction of the rectangular shape. In the lame mode quartz crystal resonator formed of the quartz substrate, the support portion is provided with a hole penetrating the element, and a holding member is injected into the hole to mount the element.

  As a detailed configuration of the above-described lame mode crystal resonator, the hole shape is processed simultaneously when forming the outer shape of the piezoelectric element by an etching process. Two or more holes are formed in the connection portion, and the hole shape is round. In addition, the problem is solved by a lame mode crystal resonator characterized by a polygonal structure.

  As described above, the present invention uses an etching solution in the manufacturing method of the lame mode crystal resonator, and the LQ1T cut or LQ2T cut crystal substrate is processed by wet etching, so that the mounting strength at the support portion and the mounting efficiency by the bonding member are used. In order to increase the mechanical strength of the element, the hole shape is processed at the same time when the outer shape of the piezoelectric element is formed by an etching process, a through hole is formed, and a bonding member is injected to increase the mechanical strength against dropping and impact. Increase. At the same time, the mounting strength of the element is ensured, and fluctuations in electrical characteristics during a drop 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 using a piezoelectric element as a substrate. When one dimension of the side ratio of the substrate is 1, the number of vibration modes that exist innumerably on a plate satisfying the integer ratio (1 to n) of the other dimension is determined. This is called a mode oscillator. 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. 1 (a) and FIG. 1 (b). 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.

  Now, as a feature of the present invention, a perspective view shown in FIG. 4 will be described as an example. It is a lame mode vibrator having a form in which a hole 5 is formed in a connection part 3 of an element having a higher-order vibration form. When compared with FIG. 3, the specific operation is as follows. When a charge is applied to a rectangular piezoelectric element composed of the vibration part 4, the support part 2, and the connection part 3, the corners of the piezoelectric element are taken as nodes. An LQ1T cut or an LQ2T cut that generates a vibration form of contour vibration that expands and contracts in the short direction when extending in the longitudinal direction of the rectangular shape and expands and contracts in the longitudinal direction when extending in the short direction of the rectangular shape. In the lame mode quartz crystal resonator formed of the quartz substrate, the connection portion 3 is provided with a hole 5 in order to improve the mounting strength.

  As a detailed configuration of the above-described lame mode crystal resonator, the hole shape is processed simultaneously with the outer shape formation of the piezoelectric element by an etching process, and the hole 5 is formed by two or more in each connection portion 3. The hole shape is a lame mode crystal resonator having a round or polygonal structure. In addition, there is a lead electrode end extending from the excitation electrode formed in the vibration part 4 around the connection part 3, and is electrically connected to the mounting substrate via the connection part 3. FIG. 4 does not show the excitation electrode and the extraction electrode disposed around the connection portion 3.

  In short, the features of the present invention will be described in FIG. 5 by enlarging the main part of the connection part 3. FIG. 5 (a) is a cross-sectional view taken along line AA of the connection part 3 shown in FIG. Show. A hole penetrating in the thickness direction of the element is formed, and a lead electrode is formed on the main surface of the support portion. On the other hand, FIG. 5B shows a cross-sectional state of AA after mounting. When mounted on a ceramic container or the like, the hole formed in the element by the holding member applied to the mounting surface (lower part of the element). It can be seen that the holding member is sufficiently filled up to the upper part of the element injected into the element 5.

  FIG. 6 shows the process diagram of the present invention described above. The major difference from the conventional process steps is that two steps are required: an element outer shape etching process and a process of forming excitation electrodes and extraction electrodes on the element. However, in the etching process step for forming the outer shape of the element, a major feature is that an element structure in which the effect of fixing and conduction is enhanced by forming a hole penetrating in the thickness direction of the element at a place where the element is mounted is also provided. is there. Note that the electrode patterning step shown in FIG. 6 means a separation operation for generating an electrode film from a protection (vapor deposition) film used for element formation.

  As a result, the lead electrode (not shown) present around the connection portion 3 is also electrically connected to the upper and lower portions of the element through the hole, so that the mounting strength is improved and the lead electrode is electrically connected. The condition can also be improved. As the holding member, conductive adhesive, solder, etc. are assumed, but even when mounting with bumps, the bump material overflows from the hole 5 part, and as a result, the upper and lower surfaces of the element are reliably captured and the mounting strength Will be increased.

The process described above uses a wet etching process, and the etching solution is a lame mode under a temperature environment in which a mixed solution of ammonium acid fluoride (NH ₄ F · HF) and hydrofluoric acid (HF) is warmed. It manufactures the element of the crystal oscillator.

  The shape of the hole 5 formed in the connection portion 3 is not limited to a circle or a polygon, but is formed at least in a portion where the element of the lame mode vibrator is mounted on the package of the connection portion 3. Needless to say, the hole 5 is provided with a notch in a part of the element, but the same effect can be obtained.

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 connection part (principal part) of this invention. It is a flowchart which shows the manufacturing process which forms the element 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 (piezoelectric element)
2 Support part 3 Connection part 4 Vibration part 5 Hole

Claims (3)

When a charge is applied to a rectangular piezoelectric element composed of a vibrating part, a support part, and a connecting part, the four corners of the piezoelectric element are nodes, and when extending in the longitudinal direction of the rectangular shape, the piezoelectric element expands and contracts in the short direction In addition, in the lame mode quartz crystal resonator formed of a quartz substrate of LQ1T cut or LQ2T cut, which generates a vibration form of contour vibration that expands and contracts in the longitudinal direction when extending in the short direction of the rectangular shape,
A lame mode crystal resonator, wherein a hole penetrating a piezoelectric element is provided in the connecting portion, and a holding member is injected into the hole to mount the element. 2. The lame mode crystal resonator according to claim 1, wherein at least two hole shapes are formed in the support portion. The lamellar mode crystal resonator according to claim 1, wherein the hole form is a circle or a polygonal structure.

Images