JP5396795B2 - Piezoelectric vibration device - Google Patents

Description

The present invention relates to a piezoelectric vibration device used for electronic equipment and the like.

  As an example of a surface-mount type crystal resonator, the inner bottom surface in a package (hereinafter referred to as a base) having a concave portion at one end on a long side of a rectangular crystal resonator element having a chamfered end in a plan view. There is a crystal resonator in a form that it is cantilevered and supported on a pair of mounting pads formed through a conductive adhesive. In the cantilever support bonding, the conductive adhesive is applied on the pair of mounting pads in advance (hereinafter referred to as “undercoating”), and then one end on the long side of the crystal vibrating piece is mounted, A conductive adhesive is applied to the upper part of the conductive adhesive so as to cover the upper surface of the one end of the quartz crystal vibrating piece (hereinafter referred to as “coating”), and the conductive adhesive is cured in a heated atmosphere. Is done by letting At this time, since the free end side of the quartz crystal vibrating piece is lifted by the heat shrinkage of the conductive adhesive, the vicinity of the center of the long side that is the thickest part of the quartz crystal vibrating piece is separated from the inner bottom surface of the base. . And the said recessed part is airtightly joined by atmospheric heating through sealing materials, such as a brazing material, with a rectangular-shaped cover body. Note that the sealing material melted by heating at this time forms a fillet extending from the upper surface of the bank portion surrounding the recess to the center of the lid (see FIG. 8).

  The AT-cut quartz plate generally used as the quartz crystal resonator element has an inversely proportional relationship between the thickness of the quartz plate and the oscillation frequency, and the thickness of the quartz plate increases as the frequency decreases. In the low frequency band AT-cut quartz plate, the vibration energy is confined under the excitation electrode formed in the center area of the front and back surfaces, and the quartz plate is chamfered (beveled) by chamfering (beveling) the quartz plate. The vibration energy in the supported portion (end portion) is attenuated to obtain good crystal resonator characteristics.

  With the recent reduction in size and height of piezoelectric vibration devices, the base has also been reduced in size and height. On the other hand, as the frequency of the crystal resonator is lowered, the thickness of the crystal vibrating piece is further increased, and the difference between the maximum thickness (near the center) and the minimum thickness (end) of the chamfered crystal vibrating piece is increased, It approaches the cross-sectional shape of a biconvex lens. When such a quartz crystal resonator element is bonded to the mounting pad on the inner bottom surface of the base corresponding to a reduction in height and size using a conductive adhesive, the overcoated conductive adhesive and the sealing material Since the gap with the fillet becomes very small and close, the overcoating becomes difficult. However, with only undercoating without overcoating, the free end side of the quartz crystal resonator piece cannot be lifted sufficiently due to shrinkage when the conductive adhesive is cured, and the top of the crystal vibrating piece (near the center of the main surface) The inner bottom surface of the base may come into contact (see FIG. 12). For example, Patent Literature 1 discloses a piezoelectric vibration device in which a protruding pillow portion is formed below the vicinity of the free end of a crystal vibrating piece in order to support the free end side.

Japanese Patent Laid-Open No. 2003-008387

  However, in addition to the recent miniaturization of piezoelectric vibratory devices and the miniaturization of quartz crystal vibrating pieces due to the low profile, when the thickness of the quartz vibrating piece becomes thicker than before due to low frequency, Even if the portion is disposed below the free end side of the quartz crystal vibrating piece, the top of the quartz crystal vibrating piece 2 comes into contact with the inner bottom surface of the base 1 before the pillow portion 11 as shown in FIG. The pillow part 11 is no longer functioning effectively. In addition, the height of the mounting pad 12 and the pillow part 11 is substantially equivalent here (refer virtual line). If the crystal vibrating piece comes into contact with the inner bottom surface of the base, various characteristics of the crystal resonator are adversely affected. In addition, even when the top of the crystal vibrating piece and the inner bottom surface of the base are not in contact with each other in a steady state, the free end of the crystal vibrating piece when subjected to an impact due to an external factor When the side is displaced, the top portion and the inner bottom surface of the base come into contact with each other, and defects such as scratches on the excitation electrode and oscillation stoppage may occur.

This invention is made | formed in view of this point, and it aims at providing the piezoelectric vibration device excellent in impact resistance corresponding to low profile.

In order to achieve the above object, according to the first aspect of the present invention, a pair of a concave portion for accommodating a piezoelectric vibration element having a substantially rectangular shape in plan view and a pair of one side bonded to one end side in the long side direction of the piezoelectric vibration element A mounting base and a base having a rectangular shape in a plan view provided on the inner bottom surface of the concave portion with a pillow part positioned below the other end in the long side direction of the piezoelectric vibration element are used, and the mounting pad and the piezoelectric vibration element In a state having a fillet of a sealing material that extends from the base toward the center of the lid body. The piezoelectric vibration device is hermetically sealed, wherein the base has an outer dimension in plan view having a long side of 2.5 mm and a short side of 2.0 mm, and the piezoelectric vibration element has an oscillation frequency of 16 MHz in a fundamental wave vibration mode. In the following, each end of the long side and the short side is chamfered. The thickness at the four corners of the rectangle is smaller than the thickness of the central part of the long side and the short side of the rectangle, and the front and back main surfaces of the four corners are close to each other. At least one end side of the one end side and a part of the chamfered processing region facing the inner bottom surface of the recess in the vicinity of the end surface are bonded to the mounting pad by the conductive bonding material and in the vicinity of the end surface of the piezoelectric vibration element. The conductive bonding material does not reach the chamfered region on the upper surface side, and the pillow portion is near the free end of the piezoelectric vibration element on the inner bottom surface of the concave portion and approximately at the center of the short side of the piezoelectric vibration element. is formed at a position close to the upper surface of the pillow portion is so positioned above the virtual line extending in the horizontal direction with respect to the pillow portion from the upper surface of the pair of mounting pads, the piezoelectric vibrating element When mounted on the mounting pad, the piezoelectric vibration element Top surface (in substantially the central portion of the long side of the piezoelectric vibrating element, the portion to be the thickest portion) never comes into contact with the base in the bottom. That is, since the free end side of the piezoelectric vibration element comes into contact with the pillow portion first, it is possible to prevent contact between the top of the piezoelectric vibration element and the bottom surface of the base.

  According to the above configuration, when one end side in the long side direction of the piezoelectric vibration element is cantilevered and bonded to a pair of mounting pads via, for example, a conductive bonding material paste, the piezoelectric vibration element shrinks when the conductive bonding material is cured. In some cases, the free end side of the vibrating piece is lifted and the free end side and the pillow portion are slightly separated (close state) in a steady state. Even in such a state, the area close to the free end side of the piezoelectric vibration element and the pillow portion only come into contact with each other even when subjected to an impact due to an external factor, and the piezoelectric vibration element (top) and the base There is no contact with the inner bottom surface. This is because the gap between the top portion and the base inner bottom surface is secured even when the region near the free end side of the piezoelectric vibration element comes into contact with the pillow portion.

Further, when the chamfering of the rectangular piezoelectric vibration element is performed until the cross section of the piezoelectric vibration element becomes a biconvex lens shape (bi-convex shape), the long side and the short side are processed at the same time, The short side is thickest near the center of the side. The said structure WHEREIN : The said pillow part is formed in the position close | similar to the approximate center of the short side of a piezoelectric vibration element in the free end vicinity of a piezoelectric vibration element. By forming the pillow portion at a position corresponding to the lower portion near the top in the short side direction of the piezoelectric vibration element , the absolute formation thickness (height) of the pillow portion can be minimized. Moreover, in the case of the said structure, it becomes the most effective position for suppression of the displacement amount in the short side direction of a piezoelectric vibration element at the time of receiving an external impact. That is, when the piezoelectric vibration element is bent due to an external impact, the curved top portion (substantially central portion in the short side direction) at the free end of the piezoelectric vibration element comes into contact with the pillow portion, so the amount of bending of the piezoelectric vibration element Can be suppressed, and impact resistance performance is improved. The above-described chamfering process is not limited to both surfaces (front and back) of the piezoelectric vibrating piece, and can be applied even when only one surface is chamfered. That is, the above configuration is also effective for a piezoelectric vibration element that is mounted with the surface on which the convex curved surface is formed facing the inner bottom surface of the base.

  In the above configuration, the pillow portion may be formed not only in the vicinity of the top portion in the short side direction of the piezoelectric vibration element, but also in a plurality of positions, as well as a plurality thereof. For example, the two pillow portions may be formed at positions symmetrical with respect to the short side direction with reference to a straight line passing through the center of the short side of the piezoelectric vibration element. Even in such a configuration, the positions of the upper surfaces of the two pillow portions are located above the imaginary line extending in the horizontal direction with respect to the pillow portion from the upper surface of the mounting pad.

  In the case of the above configuration, it is possible to disperse the stress received when the piezoelectric vibrating piece and the pillow portion are in contact with each other, compared to the case where the pillow portion is formed only at one place. Therefore, a highly reliable piezoelectric vibration device can be obtained due to the effect of suppressing stress concentration.

According to the first aspect of the present invention, the piezoelectric vibration element having a substantially rectangular shape in plan view has chamfered end portions of the long side and the short side, and the thickness at the four corners of the rectangle is the length of the rectangle. The front and back main surfaces of the four corners are close to each other, which is thinner than the thickness of the central part of the side and the short side. The cross-sectional shape in the vicinity of the periphery of such a piezoelectric vibration element has a shape in which the end portions in the long side and short side directions are much thinner than the central portion of the long side and short side. That is, it is a biconvex lens shape in a cross-sectional view, and has a cross-sectional shape with a large difference between the maximum thickness (near the center of each of the long side and the short side) and the minimum thickness (four corner portions) of the chamfered piezoelectric vibration element. . Even in the piezoelectric vibration element having such a shape, the upper surface of the pillow portion is located above the imaginary line extending in the horizontal direction with respect to the pillow portion from the upper surface of the pair of mounting pads. When the element is mounted on the mounting pad, the top portion of the curved surface of the piezoelectric vibration element (the substantially central portion of the long side of the piezoelectric vibration element and the thickest portion) does not come into contact with the bottom surface of the base.

According to the first aspect of the invention, the free end side of the piezoelectric vibration element comes into contact with the pillow portion first. For this reason, after joining the piezoelectric vibration element to the mounting pad, contact between the top of the curved surface of the piezoelectric vibration element and the bottom of the base can be prevented, and a highly reliable piezoelectric vibration device can be provided. .

According to the invention of claim 2, since the pillow part is a base formed of a laminate of conductive materials, the pillow part can be easily formed by laminating metal materials such as tungsten in multiple stages. can do. Excitation electrodes for driving the piezoelectric vibration element are formed on the front and back surfaces of the piezoelectric vibration element. According to the invention of claim 2, the excitation electrode and the conductive material are formed when subjected to an external impact. By designing the excitation electrode in advance so that it does not come into contact with the pillow portion, it is possible to prevent frequency changes associated with charge transfer when the excitation electrode and the pillow portion are in contact.

Alternatively, the change in frequency associated with the charge transfer can be prevented by forming the pillow portion with a conductive material and covering at least the uppermost layer with an insulating material. For example, the surface of the pillow portion is covered with an insulating resin. When the area of the excitation electrode is designed to be large up to the vicinity of the periphery of the piezoelectric vibration element, the vicinity of the free end of the piezoelectric vibration element and the pillow portion are in contact in a steady state, or are brought into contact with an external impact from a non-contact state. Even when it changes, since the contact surface (upper surface) of the pillow part is in an insulated state, there is no movement of charges due to the contact, and capacitance change between the excitation electrodes can be prevented. Therefore, a change in the frequency of the piezoelectric vibration device can be prevented, and a piezoelectric vibration device having excellent impact resistance can be obtained.

As described above, according to the present invention, it is possible to provide a piezoelectric vibration device that can cope with a reduction in height and has excellent impact resistance.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the embodiment of the present invention, a surface-mounted crystal resonator is taken as an example of a piezoelectric device.

-First embodiment-
A first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view in the long side direction of a crystal resonator showing a first embodiment of the present invention, and FIG. 2 shows a state in which a crystal resonator element is mounted on a base showing the first embodiment of the present invention. FIG. 3 is a cross-sectional view in the long side direction of the base alone taken along line AA in FIG. 2, FIG. 4 shows a state where the conductive bonding material is applied to the mounting pad in FIG. 3, and FIG. 4 shows a state where the crystal vibrating piece is bonded. In FIGS. 1 and 5, description of electrodes (details will be described later) formed on the front and back surfaces of the quartz crystal vibrating piece is omitted. 1 and FIG. 3 to FIG. 5, the external connection terminals formed on the bottom surface (back surface) of the base and the connection means for electrically connecting the external connection terminals and the mounting pads inside the base are described. Omitted. First, each of the constituent members will be described with reference to FIGS. 1 to 3, and then a method for manufacturing a crystal resonator applied in the present embodiment will be described with reference to FIGS. 4 to 5.

  As shown in FIG. 1, a crystal resonator 4 according to the present invention includes a base 1 having a concave shape in cross section, a crystal vibrating piece 2 having a rectangular shape in plan view, and a flat lid 3. One end side of the long side of the quartz crystal vibrating piece 2 is bonded to the upper portion of the mounting pad 12 formed on the inner bottom surface of the base 1 via the conductive bonding material 5. The upper surface of the bank portion 10 of the base 1 and the lid 3 are hermetically bonded via the sealing material 6.

  In FIG. 1, a base 1 is a container body having a rectangular shape in plan view, and is composed of two ceramic green sheets made of an alumina ceramic material. The base 1 is formed by laminating a frame-like second sheet 1b on top of a flat plate-like first sheet 1a, and is integrally formed by firing, and a recess 7 is formed by the frame-like second sheet 1b. Yes. The upper surface of the second sheet 1b (the upper surface of the bank portion 10) is in a flat state. In the present embodiment, the outer dimensions of the base 1 are long side × short side = 2.5 mm × 2.0 mm, and the height is about 0.5 mm. In addition, the said base external dimension is an example and is not limited to the said external dimension.

  As shown in FIG. 2, a pair of mounting pads 12 are formed in parallel on the upper surface of the first sheet 1 a on one end side in the longitudinal direction of the recess 7. The mounting pad 12 is subjected to a tungsten metallization process on the upper surface of the first sheet 1a, a nickel plating process on the upper part, and a gold plating process on the upper part. The mounting pad 12 includes an external connection terminal (not shown) formed on the bottom surface (back surface) of the base 1 and castellations (C1 to C4) formed at the four corners of the outer periphery of the base 1. It is electrically connected via. The mounting pad 12 and the external connection terminal may be electrically connected by forming a conductive path (via hole) filled with a conductor.

  As shown in FIG. 1, the pillow portion 11 is opposed to the pair of mounting pads 12, and is close to the upper surface of the first sheet 1 a on the other end side in the longitudinal direction of the recess 7 on the free end side of the crystal vibrating piece 2. Formed in position. In this embodiment, the pillow part 11 is formed of a conductive material. In this case, when the crystal vibrating piece is accommodated in the base, a part of electrodes (metal films) formed on the front and back surfaces of the crystal vibrating piece, which will be described later, do not overlap with the pillow portion 11 in plan view. Designed in the right position. In addition, when a part of said electrode overlaps with the said pillow part 11 by planar view, it is preferable to form the said pillow part 11 with an insulating material. This is because when the quartz vibrating piece is accommodated inside the base, the pillow part and the electrode are in contact with each other, or in a steady state, even if the pillow part and the electrode are separated, they are contacted by an external impact. This is to prevent charge transfer in some cases. By preventing the movement of charges, generation of unnecessary capacitance can be suppressed, and as a result, frequency changes can be suppressed. However, even when the pillow portion 11 is formed of a conductive material. By covering the uppermost layer of the pillow part with an insulating material, it is possible to prevent the charge transfer at the time of contact between the pillow part and the electrode.

  In the present embodiment, the pillow portion 11 is a rectangular parallelepiped protrusion made of a conductive material, and is formed by laminating three layers of tungsten metallization as shown in FIG. Specifically, a pillow conductor 11 and a mounting pad 12 are formed after a wiring conductor having a predetermined shape is formed on the first sheet 1a corresponding to the bottom of the two ceramic green sheets constituting the base 1 by metallization. A portion of the region other than the region and the region where the second sheet 1b is laminated is masked, and a tungsten layer for one layer is formed by squeezing tungsten. Thereafter, the above masking process is performed again, and the tungsten pad is squeezed so that two layers of mounting pads and pillows are stacked. The mounting pad 12 is subjected to the surface treatment after the squeegee treatment is performed twice. Specifically, the surface of the tungsten is first subjected to nickel plating and then gold plating, and the mounting pad 12 is completed. After performing the second squeegee process, the upper surface of the mounting pad 12 is also masked, and the formation region of the pillow portion 11 remains open. Then, by performing the third squeegee process, three layers of tungsten are laminated to complete the pillow portion 11.

  In the present embodiment, all three layers of the pillow portion 11 are formed in the same area in plan view, but the present invention is not limited to this, and the three layers may have different areas. For example, an intermediate layer (pillow part second layer) having an area smaller than that of the lowermost layer is laminated on the lowermost layer (pillow part first layer), and further, the uppermost layer having an area smaller than that of the intermediate layer is further formed thereon. The upper layer may be stacked, and the area may be reduced as it goes to the upper layer, for example, in a “pyramidal shape” (not shown). By molding the pillow portion in this way, the cross-sectional shape corresponding to the curved surface shape of the crystal vibrating piece 2 can be approximated, and the crystal vibrating piece 2 can be brought into line contact with the ridge line portion of the multi-stage pillow portion. Therefore, the drag can be dispersed at a plurality of locations.

  In the present embodiment, the pillow portion 11 has a structure in which three layers of tungsten metallization are stacked, but is not limited to this, and may have a structure in which three or more layers are stacked.

  The relative relationship in the height (thickness) direction between the pillow part 11 formed as described above and the pair of mounting pads 12 is higher in the pillow part 11 than in the mounting pad 12 as shown in FIG. Yes. That is, the upper surface of the pillow part 11 is located above the virtual line L extending in the horizontal direction with respect to the pillow part 11 from the upper surface of the pair of mounting pads 12. With such a relative positional relationship, when the one end side of the long side of the crystal vibrating piece 2 whose end is chamfered on the mounting pad 12 is bonded using a conductive bonding material, the top portion of the crystal vibrating piece 2 ( The quartz crystal vibrating piece 2 comes into contact with the pillow portion 11 before the thickest wall portion comes into contact with the bottom surface of the base (the top surface of the first sheet 1a). Therefore, even if an external impact is applied to the crystal resonator 2, contact between the top of the crystal resonator element 2 and the bottom surface of the base can be avoided. In addition, in this embodiment, although the external dimension of the said pillow part 11 is 0.2 mm x 0.15 mm, the external dimension of a pillow part is not limited to the said external dimension. In this embodiment, the height of the mounting pad 12 is about 40 μm, and the height of the pillow portion 11 is about 45 μm.

  Next, the crystal vibrating piece 2 used in this embodiment will be described. In FIG. 1, the quartz crystal resonator element 2 is an AT-cut quartz plate having a rectangular shape in plan view, and is chamfered on both the long side and the short side. The quartz crystal vibrating piece 2 has a main surface (flat portion) region, and is chamfered so that curved surfaces having two types of curvature are formed. In addition, although the crystal vibrating piece in which the end portion is chamfered is given as an example in the quartz vibrating piece, both the front and back surfaces are convex lens shapes (bi-convex shape), or only one surface is a convex lens shape (plano-convex shape). The present invention can also be applied to a crystal vibrating piece processed so as to be.

  The oscillation frequency of the quartz crystal vibrating piece used in the embodiment of the present invention is 13 MHz in the fundamental wave vibration mode. The frequency is an example, and the present invention can be applied to a frequency band other than 13 MHz in the fundamental vibration mode. However, the configuration of the present invention is particularly effective in a frequency band of 16 MHz or less in the fundamental vibration mode. To work.

  As shown in FIG. 2, excitation electrodes 21a and 21b (21b on the back side are not shown) for driving the quartz crystal resonator element 2 are drawn on the front and back surfaces of the crystal oscillator piece 2 and the excitation electrodes. Lead electrodes 22a and 22b (the back side 22b is not shown) and a pair of connection electrodes 23a and 23b (the back side 23b) connected to the lead electrode and formed on both sides of the short side end of the quartz crystal resonator element 2. Are not shown). These electrodes are formed on the quartz vibrating piece by vapor deposition or the like in the order of chromium (Cr) -gold (Au) -chromium (Cr). The film configuration of the electrode is not limited to this, for example, on the quartz diaphragm, in the order of Cr-Au, or on the quartz diaphragm, in the order of Cr-Ag (silver), or A film may be formed on the quartz diaphragm in the order of Cr—Ag—Cr. As described above, in this embodiment, when the crystal vibrating piece 2 is accommodated in the recess 7 of the base 1, the excitation electrode 21b on the back surface side of the crystal vibrating piece 2 and the pillow portion 11 are overlapped in plan view. It is a positional relationship that should not be. The above is the description of the crystal vibrating piece 2.

  Next, the lid 3 used in the present embodiment has a rectangular shape in plan view and is made of a ceramic material. The area of the lid 3 in plan view is slightly smaller than the area of the base 1 in plan view. A sealing material 6 is formed circumferentially on the lower surface of the lid 3, that is, on the periphery of the joint surface side with the upper surface of the bank portion 10 of the base 1. In the present embodiment, low melting point glass is used as the sealing material 6. Here, the width dimension of the sealing material 6 is larger than the width dimension of the bank portion 10 of the base 1. In addition, the magnitude relationship between the width dimension of the sealing material 6 formed in the said cover 3 and the width dimension of the bank part 10 of the base 1 is an example, and is not limited to this. For example, the width dimension of the sealing material 6 and the width dimension of the bank portion 10 may be equal.

  In this embodiment, a ceramic material is used as the material of the lid, but in addition to the ceramic material, a metallic material in which a nickel plating layer and a gold plating layer are formed around Kovar as a base material is used. May be. In this case, a metal brazing material such as an An—Sn alloy is used as the sealing material. This completes the description of each component of the crystal resonator.

  Next, a method for manufacturing a crystal resonator according to the present invention will be described with reference to FIGS. First, as shown in FIG. 4, the conductive bonding material 5 is applied onto a pair of mounting pads 12 formed on the inner bottom surface of the base 1 using a dispenser. Then, one end of the long side of the quartz crystal vibrating piece 2 whose end face has been processed into a predetermined shape (the end of the short side on which the pair of connection electrodes 23a and 23b is formed) is applied on the two mounting pads. Is placed on the adhesive bonding material 5. Then, the conductive bonding material 5 is cured in a heating atmosphere controlled to a predetermined temperature profile. Here, the end surface (side surface portion of the short side) of the one end side (the fixed end side) of the crystal vibrating piece 2 and the chamfering region on the lower surface side (facing the inner bottom surface of the recess 7) in the vicinity of the end surface. A part of the chamfering region on the side to be bonded is bonded to the mounting pad 12 by the conductive bonding material 5. The conductive bonding material 5 has a configuration in which a large amount of the conductive bonding material does not reach the chamfered region on the upper surface side (the chamfered region on the side not facing the inner bottom surface of the recess 7). To preferred.

  In the present embodiment, a silicone-based conductive resin bonding material is used as the conductive bonding material. The conductive bonding material 5 is not limited to the silicone-based conductive resin bonding material, and an epoxy-based conductive resin bonding material may be used in addition to the silicone-based bonding material.

  When the conductive bonding material is cured, a contraction stress is generated due to thermal contraction of the conductive bonding material, and the stress acts in a direction in which the free end side of the crystal vibrating piece 2 is lifted upward. In the present embodiment, in a state where the crystal resonator element 2 and the mounting pad 12 are joined (steady state), a part of the pillow portion 11 is close to the free end of the crystal element 2 as shown in FIG. The crystal vibrating piece 2 comes into contact with the mounting pad 12 and the pillow portion 11 and is slightly inclined in the direction of the fixed end. In addition, the pillow part 11 may be separated from the free end of the crystal vibrating piece 2 in a state where the bonding of the crystal vibrating piece 2 and the mounting pad 12 is completed (steady state).

  After the crystal vibrating piece 2 and the mounting pad 12 are joined, fine adjustment of the oscillation frequency is performed, and then the lid 3 is placed on the upper surface of the bank portion 10 of the base 1 so that the outer periphery is substantially coincident. (See FIG. 5). At this time, the sealing material 6 formed on the peripheral edge of the lid 3 is in contact with the upper surface of the bank portion 10, and the sealing material 6 is in a state of projecting toward the inside of the recess. And the sealing material 6 is melted by heating to predetermined temperature in this state, and the cover body 3 and the base 1 are airtightly joined. In the airtight joining, a fillet 61 of the sealing material 6 extending from the upper surface of the bank portion 10 toward the center of the lid 3 is formed. Thereby, more reliable airtight sealing is possible. Through the above steps, the surface-mount type crystal unit 4 is completed.

-Second Embodiment-
A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a plan view of a base showing a second embodiment of the present invention, and FIG. 7 is a sectional view taken along line BB in FIG. In FIG. 7, description of electrodes formed on the front and back surfaces of the crystal vibrating piece, external connection terminals formed on the bottom surface of the base, and castellation is omitted. In addition, about the component similar to the above-mentioned embodiment, while attaching | subjecting the same number and omitting a part of description, it has an effect similar to 1st Embodiment.

  In FIG. 6, the pillow portion 13 is formed in parallel on one end side of the bottom surface of the recess 7, and when the crystal vibrating piece 2 is accommodated inside the base 1, near the free end of the crystal vibrating piece 2 and in the short side direction. A pair of chamfered portions (curved surface portions) are arranged at positions corresponding to the chamfered portions. Specifically, a straight line connecting the centers of the two short sides of the base 1 is used as a reference line, and two pillow parts 13 are provided at one end of the bottom surface of the recess 7 with a certain distance between both sides of the reference line. Is formed. The height (thickness) of the pair of pillow parts 13 is higher on the upper surface of the pillow part 13 than a virtual line (not shown) extending in the horizontal direction from the upper surface of the mounting pad 12 toward the pillow part 13. It is formed so that it may be located in.

  As a modification of the second embodiment, as shown in FIGS. 8 to 9, the two pillow parts 13, 13 may be formed below a position spaced inward from the free end side of the crystal vibrating piece 2. Good. If the pillow part is formed at such a position, the crystal vibrating piece comes into contact with the pillow part 13 in a region that is thicker than the free end side of the crystal vibrating piece 2 when subjected to an external impact. Contact with the inner bottom surface of the base 1 at the top of the resonator element 2 can be prevented.

  Moreover, the height of the pillow part 13 is formed to be higher than the height of the pillow part 11 in the first embodiment. This is because the crystal vibrating piece 2 is chamfered not only in the long side direction but also in the short side direction, and the two pillow parts 13 are the top parts in the short side direction (the thickest part, and the short side direction). This is because it is formed at a position distant from both ends of the concave portion 7 from below the substantially central portion). That is, as shown in FIG. 7, the pillow portion 13 is brought close to the chamfered portion (curved surface portion) of the crystal vibrating piece 2. With such a structure, when the crystal vibrating piece 2 is mounted on the mounting pad 12, the top portion (the thickest portion) of the curved surface of the crystal vibrating piece 2 does not come into contact with the inner bottom portion of the base. That is, the free end side of the quartz crystal vibrating piece 2 comes into contact with the pillow portion first, and the top portion of the quartz crystal vibrating piece 2 does not come into contact with the bottom surface inside the base. Further, even if the free end side of the crystal vibrating piece 2 is lifted by the shrinkage at the time of curing of the conductive bonding material 5 and the free end side and the pillow portion 13 are slightly separated in a steady state, the external factor When receiving an impact due to the above, only the region close to the free end side of the quartz crystal vibrating piece 2 and the pillow portion 13 come into contact with each other, and the quartz crystal vibrating piece 2 (top) does not come into contact with the bottom surface of the base. . This is because a gap between the top portion and the bottom surface of the base is secured, so that a piezoelectric vibration device having excellent impact resistance can be provided.

-Third embodiment-
A third embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a plan view of a base showing a third embodiment of the present invention, and FIG. 11 is a cross-sectional view taken along the line DD of FIG. 10 to 11, description of electrodes formed on the front and back surfaces of the quartz crystal resonator element, external connection terminals formed on the bottom surface of the base, and castellation is omitted. In addition, about the component similar to the above-mentioned embodiment, while attaching | subjecting the same number and omitting a part of description, it has an effect similar to 1st Embodiment.

  According to FIGS. 10 to 11, the crystal vibrating piece 2 having a substantially rectangular shape in plan view has its long side and short side end chamfered, and the thicknesses at the four corners of the rectangle are the long side and short side of the rectangle. It is thinner than the thickness of the center. And the front and back main surfaces of the four corners of the quartz crystal vibrating piece 2 are close to each other. The cross-sectional shape in the vicinity of the periphery of such a quartz crystal vibrating piece 2 is such that the ends in the long side and short side directions are much thinner than the center part of the long side and short side, and the plane of the quartz crystal vibrating piece The shape is such that there are few flat regions (main surfaces) near the center and many curved regions around them. That is, it is a substantially biconvex lens shape in cross-sectional view, and has a cross-sectional shape in which the difference between the maximum thickness (near the center of the long side and the short side) and the minimum thickness (four corners) of the chamfered piezoelectric vibration element is large. Yes.

  Also in the quartz crystal resonator element having such a shape, the upper surface of the pillow portion 13 is located above the imaginary line L extending in the horizontal direction with respect to the pillow portion from the upper surfaces of the pair of mounting pads 12 and 12. When the crystal vibrating piece 2 is mounted on the mounting pad, the top of the curved surface of the crystal vibrating piece (the central portion of the long side of the crystal vibrating piece and the thickest part) is in contact with the bottom surface of the base. There is no.

  In the present embodiment, the pillow portion 13 is formed below the two corners on the free end side of the crystal vibrating piece 2. The pillow portion 13 is formed of a three-layer laminate, and an intermediate layer having a smaller area than the lowermost layer is laminated on the lowermost layer, and further, the lowest layer having an area smaller than that of the intermediate layer is formed on the intermediate layer. The upper layer is laminated, and the area is smaller as going to the upper layer, and the layers are gradually biased in one direction. That is, when the crystal vibrating piece 2 is mounted on the pair of mounting pads 12 and 12, the edge (region near the corner) of the crystal vibrating piece is positioned in the lowermost layer and the intermediate layer in plan view. Stepped pillow parts 13, 13 that are gradually biased in one direction are arranged. By forming such a pillow portion, the crystal vibrating piece 2 can be stably mounted inside the base. Specifically, the conductive bonding materials 5 and 5 are formed on the pair of mounting pads 12 and 12, the crystal vibrating piece is held using a suction tool, and one short side end portion of the crystal vibrating piece is conductive. When placing on the bonding material, a slight rotation may occur in the quartz crystal vibrating piece to cause placement displacement, but the above-described displacement can be suppressed by the pillow portion of this structure. That is, by arranging the pillow part 13 at an appropriate position on the bottom surface of the base, even if rotation occurs when the crystal vibrating piece is mounted inside the base, the crystal vibrating piece comes into contact with the uppermost layer of the pillow part. This is because it has a function of “guide” to be guided to an appropriate position. In addition, the pillow part of this structure may be formed in the state connected with the bank part 10 of the base.

  In the embodiment of the present invention, the sealing material is formed only on the lid side and the sealing material is not formed on the base side. However, the present invention is not limited to the above-described configuration. A configuration in which the sealing material is formed only on the top surface of the part or a configuration in which the sealing material is formed on both the lid and the base may be employed.

  Furthermore, in the embodiment of the present invention, a glass material is taken as an example of a sealing material, but a ceramic base and a metal lid are used, and laser sealing using a brazing material such as a silver brazing material as the sealing material, It is also possible to apply sealing by electron beam sealing. Furthermore, in the embodiment of the present invention, a surface-mount type crystal resonator is taken as an example, but other surface-mount type piezoelectric elements used in electronic devices such as a crystal filter and a crystal oscillator incorporating a crystal and other electronic component elements are used. It can also be applied to vibration devices.

  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 vibration devices.

Sectional drawing in the long side direction of the crystal oscillator which shows the 1st Embodiment of this invention. The top view which shows the state by which the crystal vibrating piece was mounted in the base of this invention. Sectional drawing in the long side direction of the base single-piece | unit in the AA line of FIG. FIG. 4 is a cross-sectional view showing a state where a conductive bonding material is applied in FIG. 3. FIG. 5 is a cross-sectional view illustrating a state where a crystal vibrating piece is bonded in FIG. 4. The top view of the base which shows the 2nd Embodiment of this invention. Sectional drawing in the BB line of FIG. The top view of the base which shows the other example of the 2nd Embodiment of this invention. Sectional drawing in the CC line | wire of FIG. The top view of the base which shows the 3rd Embodiment of invention. Sectional drawing in the DD line | wire of FIG. Sectional drawing of the long side direction which shows the example of the conventional crystal oscillator. Sectional drawing of the long side direction which shows the example of the conventional crystal oscillator.

DESCRIPTION OF SYMBOLS 1 Base 2 Crystal vibrating piece 3 Cover body 4 Crystal oscillator 5 Conductive joining material 6 Sealing material 7 Recessed part 10 Bank part 11, 13 Pillow part 12 Mounting pad 1a 1st sheet 1b 2nd sheet

Claims (2)

A recess for accommodating the piezoelectric vibration element having a substantially rectangular shape in plan view, a pair of mounting pads joined to one end side in the long side direction of the piezoelectric vibration element, and a lower side of the other end side in the long side direction of the piezoelectric vibration element Using a base in a rectangular shape in a plan view comprising a pillow portion located on the inner bottom surface of the recess,
The mounting pad and one end side in the long side direction of the piezoelectric vibration element are bonded via a conductive bonding material, and the base and the plate-shaped lid are extended from the base toward the center of the lid. A piezoelectric vibration device hermetically sealed in a state having a stop fillet,
The base has an outer dimension in plan view having a long side of 2.5 mm and a short side of 2.0 mm,
The piezoelectric vibration element has an oscillation frequency of 16 MHz or less in the fundamental vibration mode, and ends of the long side and the short side are chamfered, and the thickness at the four corners of the rectangle is set to the long side and the short side of the rectangle. It is thinner than the thickness of each central part, and the front and back main surfaces of the four corners are close to each other,
At least an end surface on one end side in the long side direction of the piezoelectric vibration element and a part of a chamfering region facing the inner bottom surface of the recess in the vicinity of the end surface are bonded to the mounting pad by the conductive bonding material. The conductive bonding material does not reach the chamfering region on the upper surface side in the vicinity of the end face of the piezoelectric vibration element,
The pillow part is formed at a position on the inner bottom surface of the recess, near the free end of the piezoelectric vibration element and close to the approximate center of the short side of the piezoelectric vibration element,
The upper surface of the pillow part is located above the imaginary line extended in the horizontal direction with respect to the pillow part from the upper surface of the pair of mounting pads.   The piezoelectric vibration device according to claim 1, wherein the pillow portion is formed of a laminate of conductive materials.

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