JP2014165767A - Piezoelectric vibration device - Google Patents

Abstract

The present invention provides a piezoelectric vibration device that suppresses generation of cracks in solder mounting on an external substrate or the like and has high bonding reliability.
An outer bottom surface 200 of a crystal resonator base 2 has a substantially rectangular shape in a plan view, and a pair of external terminals 5 and 5 are disposed close to and symmetrically with respect to a center point O of the outer bottom surface. Out of the corners of the external terminal 5 that is rectangular in plan view, from the set of corners C1 and C6 that are point-symmetric with respect to the center point O, the base outer bottom surface that is closest to each of the corners C1 and C6. A pair of extraction electrodes 6A and 6B are formed point-symmetrically with respect to the center point O toward the pair of short sides W1 and W2.
[Selection] Figure 2

Description

  The present invention relates to a piezoelectric vibration device that is conductively bonded to an external substrate via solder.

  Piezoelectric vibration devices such as crystal resonators and crystal oscillators are widely used as timing devices for various communication devices. Taking a surface-mount type crystal resonator as an example of a piezoelectric vibration device, a crystal resonator has a crystal resonator element mounted inside a rectangular parallelepiped package (base), and a lid is bonded to the base. It has a structure in which the pieces are hermetically sealed. A pair of external terminals for connection to the outside is provided on the outer bottom surface of the base, and the external terminals are electrically connected via excitation electrodes formed on the front and back surfaces of the quartz crystal vibrating piece and the internal wiring of the base. Connected. In general, the external terminals are formed in a rectangular shape in plan view, and the number of terminals arranged varies depending on the type of piezoelectric vibration device. In such a surface-mount type crystal resonator, the external terminals are conductively bonded via solder to a land pattern (mounting pad) provided on an external substrate.

  By the way, one of the uses of the crystal resonator is, for example, an in-vehicle use. In a vehicle-mounted application, the temperature range used is wider than that of a general application, and vibrations, impacts, and the like are applied. Therefore, the vehicle is used in a severer environment than a normal application. Therefore, high bonding reliability of the crystal unit on the external substrate is required. However, for example, in a thermal shock test (heat cycle test), cracks may occur in the solder that fixes the crystal unit to the external substrate. The cracks are generated at the outer periphery of the solder where stress is concentrated. This is because the strain is proportional to the product of the length of the portion where the dissimilar materials of the base, solder, and external substrate are joined (distance from the center point of the outer bottom surface of the base) and the difference in linear expansion coefficient of these dissimilar materials. Because. In particular, in the case of a rectangular external terminal, stress tends to concentrate at the corners which are discontinuous portions.

  As described above, when cracks occur in the solder, the progress of the cracks may lead to problems such as poor connection and dropout of the crystal unit. For example, Patent Literatures 1 to 3 disclose a piezoelectric vibration device in which the shape of the external terminal is devised in order to solve such a problem.

JP 2006-5027 A JP 2007-294649 A JP 2011-151762 A

  In Patent Documents 1 and 2, since cracks are likely to be formed in the solder connection portion far from the center point of the outer bottom surface of the package, solder connection due to stress concentration is formed by forming chamfered portions at the corners of the external terminals. It is disclosed to prevent the occurrence of cracks in the part. However, the external terminals in Patent Documents 1 and 2 are arranged near the four corners of the package outer bottom surface or a pair of opposing short sides, and are formed at positions close to the center point of the package outer bottom surface. Absent. Therefore, even if the stress concentration at the corners of the external terminals can be alleviated, the strain is increased because the distance from the center point of the outer bottom surface of the package is large.

  Further, in Patent Document 3, the total dimension in the length direction of the pair of external terminals on the outer bottom surface of the rectangular package is set to 70% or more, and the opposing sides in the central region of the outer bottom surface are gradually reduced in curvature. The mounting terminal is disclosed by being bent into a shape. In Patent Literature 3, the sides of the external terminals have a curvature, and a part of the pair of external terminals extends to a position close to the center point of the outer bottom surface of the package. However, the external terminals occupy 70% or more with respect to the length direction of the outer bottom surface of the package, and extend to the vicinity of the side portion of the outer bottom surface of the package. That is, the external terminals in Patent Document 3 are not formed only at positions close to the center point of the package outer bottom surface. Therefore, since there is a region far from the center point of the outer bottom surface of the package, it is difficult to suppress distortion.

  The present invention has been made in view of this point, and an object of the present invention is to provide a piezoelectric vibration device that suppresses the generation of cracks in solder mounting on an external substrate or the like and has high bonding reliability.

  In order to achieve the above object, the present invention provides a piezoelectric vibration device in which an external terminal provided on an outer bottom surface of a package is conductively bonded to an external substrate via solder, and the outer surface of the package is substantially rectangular in a plan view. A pair of external terminals are disposed close to and symmetrically with respect to the center point of the outer bottom surface, the external terminals are substantially rectangular in plan view, and the corners of the respective external terminals of the rectangle, From one set of corners that are point-symmetric with respect to the center point, either one set of long sides or one set of short sides that are closest to each of the set of corners. A pair of extraction electrodes are formed point-symmetrically with respect to the center point of the outer bottom surface of the package.

  According to the said invention, a pair of external terminal is arrange | positioned near and symmetrical with respect to the center point of a package outer bottom face. That is, a pair of external terminals are arranged near the center of the outer bottom surface of the package. By arranging the pair of external terminals in such a positional relationship, the distance from the center point of the outer bottom surface of the package is reduced, and distortion of the solder when mounting the piezoelectric vibration device can be suppressed.

  Further, according to the above-described invention, in addition to the above-described effects, the stress acting on the corner portion of the external terminal that is likely to be a starting point of a crack can be relaxed. This is because the pair of extraction electrodes are extended from the corners of the external terminals, so that the discontinuity at the connection between the corners and the extraction electrodes is alleviated. That is, the corners of the external terminals are blunted.

  Further, since the pair of extraction electrodes in the present invention is formed point-symmetrically with respect to the center point of the package outer bottom surface, the balance at the package outer bottom surface is maintained, and the stress acting on each extraction electrode can be offset. . With such a configuration, even if a crack occurs in the solder, the progress can be delayed, so that the life of the piezoelectric vibration device can be extended.

  As described above, with the piezoelectric vibration device according to the present invention, the distortion of the solder when the piezoelectric vibration device is mounted can be suppressed, and the stress acting on the corner of the external terminal that is likely to start a crack can be relieved. Occurrence can be suppressed.

  In order to achieve the above object, a pair of corners of the pair of external terminals is the farthest side from the center point of the package outer bottom surface among the four sides constituting the rectangle of each external terminal. It may be a corner on one end side.

  According to the above invention, the distance from the center point of the package outer bottom surface is made farthest from the center point in the external terminal as compared with the conventional external terminal configuration arranged near the side portion of the package outer bottom surface. By extending the extraction electrode from the corner on one end side of the side, the stress acting on the corner of the external terminal can be relaxed while suppressing distortion. Thereby, generation | occurrence | production of a crack can be suppressed.

  In order to achieve the above-mentioned object, the pair of extraction electrodes has a pair of long sides of the outer surface of the package that is closest to each of the pair of corners from each of the pair of corners of the external terminal. Or you may form in the diagonal direction toward any one set side of a set of short sides.

  According to the above invention, when the extraction electrode is formed in the oblique direction, the side of the external terminal facing the side of the outer bottom surface of the package from which the extraction electrode extends out of the two sides constituting the corner portion, and the extraction electrode Is an angle other than 90 degrees. That is, the pair of extraction electrodes are formed obliquely and point-symmetrically with respect to the center point of the package outer bottom surface, thereby approaching the extending direction of the diagonal line of the package outer bottom surface that is substantially rectangular in plan view. As a result, the pair of lead electrodes extending in the oblique direction functions like “stitching” on the outer bottom surface of the package, thereby providing a package reinforcing effect. Further, when the solder is melted and the piezoelectric vibration device is bonded onto the external substrate, the melted solder also gets wet with the pair of lead electrode portions extending in the oblique direction, and the solder bonding strength can be supplemented.

  In order to achieve the above object, of the two sides constituting each of the pair of corners of the external terminal, one side facing the side of the package outer bottom surface where a pair of extraction electrodes is not formed, and the extraction electrode The angle formed by the extending direction may be 180 degrees or more.

  According to the above configuration, the occurrence of cracks can be more effectively suppressed in addition to the above-described “bracing” effect. This is the same as the side of the package outer bottom facing the side from either of the corners on both sides of the outer side of the package outer bottom among the sides constituting the rectangular external terminal in plan view The case where the extraction electrode is extended toward the location will be described. In the following, for the sake of convenience, description is given focusing on one of the pair of external terminals.

  First, when an extraction electrode is extended in an oblique direction from one corner of one side of an outer terminal with respect to the center point of the package outer bottom surface of one external terminal toward the side of the package outer bottom surface facing the side Will be described. In this case, of the two sides constituting the corner of one end of the side, the angle formed by one side facing the side of the package outer bottom surface where the extraction electrode is not formed and the extension direction of the extraction electrode is 180 degrees or less. In some cases, the extraction electrode extends to the corner of the one end so as to approach the corner of the latest outer bottom surface of the package. There is no region where the extraction electrode is close to the corner of the other end of the side.

  Next, from the corner of the other end of the side that is outside the center point of the outer bottom surface of the package of one external terminal, the side of the outer surface of the package that faces the side extends from the corner of one end of the side. The case where the extraction electrode is extended in an oblique direction toward the same position as the case where it is extended will be described. In this case, the angle formed between the extending direction of the extraction electrode extending in the oblique direction and one side facing the side of the outer bottom surface of the package where the extraction electrode is not formed, of the two sides constituting the corner of the other end is 180 degrees. That's it.

  In such a case, there is a region where the extraction electrode is close to the corner of one end of the side. That is, when the angle is 180 degrees or more, even if there is a corner portion at either one of both ends of the side outside the center point of the package outer bottom surface of the external terminal, the extraction electrode It will be extended in the direction gradually approaching the side including the corner. As a result, even if the corner portion exists, the stress concentration on the corner portion can be relaxed by the extraction electrode on the outer side.

  Of the two sides constituting each of the pair of corners of the external terminal, the angle formed by one side facing the side of the outer bottom surface of the package where the pair of extraction electrodes are not formed and the extending direction of the extraction electrode is 180 degrees. By forming the extraction electrode having the above angle, it is possible to dispose one end side of the extraction electrode at a position closer to the center of the opposite side of the package outer bottom surface. It is well-balanced and effective for stress relaxation.

  According to the invention, the extraction electrode can be formed longer than when the angle is 180 degrees or less. Thereby, even if a crack occurs in the outer periphery of the package, the propagation of the crack to the external terminal side can be delayed, so that the life of the piezoelectric vibration device can be extended.

  In order to achieve the above object, conductive bumps smaller than the external terminals are formed on the pair of external terminals so as to protrude backward from the outer peripheral edge of the external terminals toward the center of the external terminals. Also good.

  According to the above configuration, the conductive bumps smaller than the external terminals are formed on the pair of external terminals so as to protrude from the outer peripheral edge of the external terminal toward the center of the external terminal. The stress on the outer periphery of the terminal and the strain in the thickness direction of the external terminal can be alleviated. Thereby, generation | occurrence | production of a crack can be suppressed.

  As described above, according to the present invention, it is possible to provide a piezoelectric vibration device having high bonding reliability by suppressing the generation of cracks in solder mounting on an external substrate or the like.

1 is a schematic cross-sectional view showing a crystal resonator according to a first embodiment of the invention. FIG. 3 is a bottom view of the crystal resonator according to the first embodiment of the invention. Simulation diagram of shear strain of solder according to the first embodiment of the present invention Modification of the first embodiment of the present invention A bottom view of a crystal resonator according to a second embodiment of the present invention. A bottom view of a crystal resonator according to a third embodiment of the present invention. Simulation diagram of solder shear strain according to the third embodiment of the present invention Modification 1 of the third embodiment of the present invention Modification 2 of the third embodiment of the present invention Fourth embodiment of the present invention Fifth embodiment of the present invention Sixth embodiment of the present invention Simulation diagram of solder shear strain in conventional external terminals

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a crystal resonator as an example of a piezoelectric vibration device. The crystal resonator in the embodiment of the present invention is a surface-mount type crystal resonator having a substantially rectangular parallelepiped shape. In this embodiment, the external dimensions of the crystal resonator in plan view are 3.2 mm × 2.5 mm.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a crystal resonator 1 has a structure in which a crystal vibrating piece 4 is mounted inside a base (package) 2 having a recess 12 and a lid 3 is bonded to the base 2 via a bonding material 11. By joining the lid 3 and the base 2, the crystal vibrating piece 4 in the base is hermetically sealed. Specifically, the upper surface of the bank portion 7 standing so as to surround the concave portion 12 of the base 2 and the outer peripheral edge portion of the lid 3 are joined (sealed) via a bonding material 11 provided on the upper surface of the bank portion 7. Is stopped). As the joining means, a method such as a method of sealing by heating and melting glass resin or the like, or a seam welding method is used.

  In FIG. 1, the quartz crystal vibrating piece 4 is a flat AT-cut quartz crystal diaphragm, and a pair of excitation electrodes (not shown) for driving the quartz diaphragm are formed oppositely on the front and back main surfaces of the quartz crystal diaphragm. From each of the pair of excitation electrodes, connection electrodes used for electromechanical connection with the base are led out to one end side of the crystal diaphragm (not shown). This connection electrode is conductively bonded to a pair of pad electrodes provided inside the base 2 described later via a conductive adhesive.

  In FIG. 1, the lid 3 has a plate shape and is made of an insulating material such as alumina. Here, the material of the lid 3 is not limited to an insulating material, and may be a metallic material.

  In FIG. 1, a base 2 is a laminated body of a plurality of ceramic green sheets, and is integrally formed by firing. In the present embodiment, the base 2 has a rectangular parallelepiped shape, and a concave portion 12 having a rectangular shape in plan view is provided inside the base 2. A step 8 is formed on one end of the inner bottom surface of the recess 12, and a pair of pad electrodes 9 and 9 are formed on the upper surface of the step 8. The pair of pad electrodes 9, 9 are conductively joined to a connection electrode (not shown) provided on one end side of the crystal vibrating piece 4 via a conductive adhesive 10.

  The outer bottom surface 200 of the base 2 has a rectangular shape in plan view, and a pair of external terminals 5 and 5 and a pair of extraction electrodes 6 (6A and 6B) are formed. In the present embodiment, the external terminal, the extraction electrode, the pad electrode described above, and the like have a structure in which a nickel plating layer is stacked on the tungsten surface and a gold plating layer is further stacked thereon after printing and baking tungsten. The pair of external terminals 5 and 5 are electrically connected to the pair of pad electrodes 9 and 9 via an internal wiring conductor (not shown) formed inside the base material of the base 2. Although description is omitted in the embodiment of the present invention, a notch portion (a castellation) in which a part of the outer surface of the base 2 is notched in the vertical direction of the base and a conductor is exposed on the inner wall surface thereof. ) May be provided.

  In the present embodiment, as shown in FIG. 2, the pair of external terminals 5 and 5 are disposed close to and symmetrically with respect to a center point O (hereinafter simply referred to as “center point O”) of the base outer bottom surface 200. ing. The center point O is a virtual point and is displayed in the drawing for convenience of explanation. Specifically, the pair of external terminals 5 and 5 are formed symmetrically with respect to an imaginary line substantially parallel to the short side of the base passing through the center point O. In the present embodiment, the gap between the pair of external terminals 5 and 5 is 0.6 mm. The gap between the pair of external terminals is an example, and application of the present invention is not limited to the dimensions (preferably 0.5 mm to 1.0 mm).

  Then, as shown in FIG. 2, the pair of extraction electrodes 6A and 6B is connected to the pair of corners C1 and C6 that are point-symmetric with respect to the center point O of the pair of external terminals 5 and 5. Each of the corners (C1, C6) is formed substantially parallel to the long side of the base outer bottom surface toward the pair of short sides W1, W2 which are the latest base outer bottom surface. That is, in the present embodiment, the extraction electrodes 6A and 6B extend from each of the corners on one end side of 5a and 5b, which are the farthest sides from the center point O among the four sides constituting the rectangle of each external terminal. Has been issued. In FIG. 2, the four corners of the external terminal located on the left side with respect to the center point O are C1 to C4 (C3 and C4 are not shown) clockwise from the outside with respect to the center point O. The four corners of the external terminal located on the right side with respect to the center point O are C5 to C8 (C7 and C8 are not shown) counterclockwise from the outside with respect to the center point O.

  According to the first embodiment of the present invention, the distance from the center point of the package outer bottom surface is reduced while the distance from the center point of the package outer bottom surface is reduced as compared with the conventional external terminal configuration arranged near the side portion of the package outer bottom surface. By extending the extraction electrode from the corner on one end side farthest from the center point, the stress acting on the corners (C1, C6) of the external terminal can be relaxed while suppressing distortion. Thereby, generation | occurrence | production of a crack can be suppressed.

  Specifically, the extraction electrode 6A is formed substantially parallel to the long side L1 (L2) from the corner C1 toward the short side W1. Here, in the outer bottom surface 200 having a rectangular shape in plan view, a pair of opposing short sides is W1 and W2, and among these, the shortest side closest to the corner C1 is W1. The extraction electrode 6B is formed substantially parallel to the long side L1 (L2) from the corner C6 toward the short side W2. Here, the shortest side closest to the corner C6 is W2.

  In FIG. 2, the pair of extraction electrodes 6 </ b> A and 6 </ b> B is formed point-symmetrically with respect to the center point O. In FIG. 2, C1 and C6 are selected as a set of corners that are symmetrical with respect to the center point O of the pair of external terminals 5 and 5, but C2 and C5 are selected as a set of corners. It goes without saying that the extraction electrode may be selected and extended toward the latest pair of short sides W1, W2 for each of the corners C2, C5.

  FIG. 3 shows a simulation result of the shear strain of the solder in the XZ direction using the finite element method for the external terminal configuration shown in FIG. In FIG. 3, only one of the pair of external terminals is displayed, and the outline of the outer bottom surface of the base is not shown. Although omitted in FIG. 2, in this simulation, the castellation is formed on the side surface of the short side, and the analysis is performed under the condition that the conductive metal bump protrudes in the region of the external terminal. ing. As a condition for this simulation, a linear analysis is performed in consideration of the thermal expansion of each member when heat of + 125 ° C. is applied to + 25 ° C. of the reference temperature.

  According to FIG. 3, it can be seen that the shear strain of the solder at the connection portion between the external terminal and the extraction electrode is alleviated (the portion displayed in green). In order to recognize this, for comparison, FIG. 13 (displayed in a state where the external terminal is divided in half in the short side direction of the base) in the solder mounting on the external terminal formed near the short side of the outer bottom surface of the base. The simulation result of the shear strain of solder is shown. In FIG. 13, the connection portion between the external terminal and the extraction electrode is red, whereas in the first embodiment of the present invention, it is green, and it can be seen that the shear strain is relaxed in the present invention. .

  According to the configuration of the present embodiment, the pair of external terminals 5 and 5 are disposed close to and symmetrically with respect to the center point O on the outer bottom surface of the package. Solder distortion during mounting of the child 1 can be suppressed.

  Furthermore, according to the said structure, in addition to the said effect, the stress which acts on the corner | angular part of the external terminal which becomes a starting point of a crack can be relieve | moderated. This is because the pair of extraction electrodes 6A and 6B extends from the corners C1 and C6 of the pair of external terminals 5 and 5, so that the discontinuity of the connection portion between the corner and the extraction electrode is alleviated. by. That is, the corners of the external terminals are blunted.

  Further, according to the above configuration, the pair of extraction electrodes 6A and 6B is formed point-symmetrically with respect to the center point of the package outer bottom surface, so that the balance on the package outer bottom surface is maintained and the stress acting on each extraction electrode Can be offset. With such a configuration, even if a crack is generated in the solder, the progress can be delayed, so that the life of the crystal unit can be extended.

<Modification of First Embodiment of the Present Invention>
A modification of the first embodiment of the present invention is shown in FIG. In FIG. 4, the pair of rectangular external terminals 5 ′ and 5 ′ are arranged so that the long side is substantially parallel to the long side of the base outer bottom surface, and the center point O of the pair of external terminals 5 ′ and 5 ′. A pair of corners C2 and C5 that are point-symmetric with respect to the pair of corners C2 and C5 toward the pair of long sides L1 and L2 that are closest to each of the pair of corners C2 and C5. The extraction electrodes 6C and 6D are formed symmetrically with respect to the center point O. Even in such a configuration, the same effect as the configuration according to FIG. 2 described above can be obtained.

<Second Embodiment of the Present Invention>
A second embodiment of the present invention is shown in FIG. In this embodiment, the description of the same configuration as that of the above-described first embodiment of the present invention is omitted, and differences from the first embodiment will be mainly described. In FIG. 2, the pair of external terminals 50, 50 are formed in the same shape, position, and size as in the first embodiment of the present invention, but the pair of extraction electrodes 6E, 6F is the long side of the base outer bottom surface. It differs from the first embodiment in that it is formed in an oblique direction with respect to L1 (L2).

  Specifically, the pair of extraction electrodes 6E and 6F is formed on the outer bottom surface of the package that is closest to each of the corner portions C2 and C5 from each of the pair of corner portions C2 and C5 of the pair of external terminals 50 and 50. Extending toward the pair of short sides W1 and W2 in the diagonally upward left direction or diagonally downward right.

  According to such a configuration, the extraction electrodes 6E and 6F are formed in an oblique direction with respect to the long side L1 (L2) of the base outer bottom surface, thereby leading out the two sides constituting the corner portion C2 (C5). The angle α formed by the lead electrode and the side 5a (5b) of the external terminal facing the side W1 (W2) of the package outer bottom surface from which the electrode extends is an angle other than 90 degrees. That is, the pair of extraction electrodes are formed in an oblique direction and point-symmetric with respect to the center point O, thereby approaching the extending direction of the diagonal line DL on the outer bottom surface of the package that is substantially rectangular in plan view. As a result, the pair of extraction electrodes 50, 50 extending in an oblique direction functions like “stitching” on the outer bottom surface 200 of the package, and provides the reinforcing effect of the base 2. Also, when the solder is melted and the crystal unit is bonded to the external substrate, the melted solder gets wet also in the formation region of the pair of extraction electrodes 6E and 6F, and the solder bonding strength can be supplemented.

<Third Embodiment of the Present Invention>
A third embodiment of the present invention is shown in FIG. In this embodiment, the pair of external terminals 51, 51 are formed in the same shape, position, and size as in the second embodiment of the present invention, but the pair of extraction electrodes 6G, 6H are extended. The corners of the external terminals 51 and 51 are different from those of the second embodiment. Specifically, in FIG. 6, the positions of the pair of extraction electrodes 6 </ b> E and 6 </ b> F shown in FIG. 5 are substantially the same positions as the short sides W <b> 1 and W <b> 2. It has become. That is, the base outer bottom surface in which the pair of extraction electrodes 6G (6H) is not formed among the two sides constituting C1 (C6) which is a corner on one end of the side 5a (5b) outside the center point O. An angle θ formed by one side 5c (5d) facing the sides L1 and L2 and the extending direction of the extraction electrode 6G (6H) is 180 degrees or more.

  According to the above configuration, the occurrence of cracks can be more effectively suppressed in addition to the above-described “bracing” effect. This will be described with reference to the second embodiment of the present invention. In the following, for convenience, the description will be given focusing on one of the pair of external terminals.

  First, in FIG. 5 (second embodiment), one of the two sides constituting the corner C2 at one end of the side 5a of the external terminal 50 is opposed to L1, which is the side of the base outer bottom surface where the extraction electrode 6E is not formed. An angle θ formed by the side (reference numeral omitted) and the extending direction of the extraction electrode 6E is 180 degrees or less. As a result, the extraction electrode 6E extends to the corner C2 in a direction approaching the corner of the outer bottom surface of the base that is closest to the corner C2. And there is no region where the extraction electrode is close to C1 which is the corner of the other end of the side 5a.

  On the other hand, in FIG. 6 (third embodiment), as described above, a pair of lead electrodes out of two sides constituting C1 which is a corner portion on one end side of the side 5a outside the center point O as described above. An angle θ formed by one side (5c) facing the side L2 of the base outer bottom surface where 6G is not formed and the extending direction of the extraction electrode 6G is an angle of 180 degrees or more. And as shown in FIG. 6, the area | region where the extraction electrode 6G adjoins exists in the vicinity of the corner | angular part C2. That is, the extraction electrode 6G extends in a direction gradually approaching the side 5a including the corner portion C2. With such a configuration, even if the corner portion C2 exists, the concentration of stress on the corner portion C2 can be alleviated by the extraction electrode 6G outside the corner portion C2. The part of the corner C2 is not necessarily a right angle, and the part of the corner C2 may be chamfered or curved. By adopting such a shape, stress concentration can be further relaxed.

  Further, by forming an extraction electrode having an angle θ of 180 degrees or more, one end side of the extraction electrode is located at a position near the center of the opposing side (two opposing long sides or two opposing short sides) of the base outer bottom surface. Therefore, the extraction electrode is arranged in a more balanced manner with respect to the outer bottom surface of the base, which is effective for stress relaxation.

  Further, according to the third embodiment of the present invention, the extraction electrode can be formed longer than when the angle θ is 180 degrees or less. Thereby, even if a crack occurs in the outer periphery of the base, the propagation of the crack to the external terminal side can be delayed, so that the life of the crystal unit can be extended.

  Next, FIG. 7 shows a simulation result of the shear strain of the solder in the XZ direction using the finite element method for the external terminal configuration shown in FIG. In FIG. 7, only one of the pair of external terminals is displayed, and the outline of the bottom surface of the base is not shown. In the simulation results shown in FIG. 7, the castellation is formed on the short side surface. In FIG. 7A, the conductive metal bumps are formed in a protruding manner in the external terminal region, and in FIG. 7B, the metal bumps are not formed in the external terminal region. It has become. Other conditions are the same as the simulation conditions described in FIG.

  According to FIG. 7, it can be seen that the shear strain at the connection portion between the external terminal and the extraction electrode is alleviated (the portion displayed in green). FIG. 7A shows the case where the extraction electrode extends in an oblique direction toward one end of the castellation formed at the edge of the short side of the base, and FIG. 7B shows the edge of the short side of the base. In this case, the extraction electrode extends in an oblique direction toward the center of the castellation formed in the portion. 7 (a) and 7 (b) that the shear strain at the connection portion between the external terminal and the extraction electrode is alleviated.

<Variation 1 of the third embodiment of the present invention>
As shown in FIG. 8 as a first modification of the third embodiment of the present invention, curved surfaces R1, R2 (R1 and R2 have the same curvature) on the connection portion side with the external terminals 52, 52 of the extraction electrodes 6J, 6K. ) May be included. By having such curved surfaces R1 and R2 on the connection portion side with the external terminals 52 and 52, the discontinuity of the connection portion between the lead electrode and the corner portion of the external terminal is alleviated. As a result, it is possible to relieve stress acting on the corners of the external terminals that are likely to start cracks.

<Modification 2 of the third embodiment of the present invention>
FIG. 9 shows a second modification of the third embodiment of the present invention. In the third embodiment of the present invention, the pair of external terminals are formed in parallel in the long side direction of the base. However, as a modification of the third embodiment, as shown in FIG. , 53 may be formed in parallel in the short side direction of the base. Even in this case, from the pair of corners C1 ′ and C6 ′ that are symmetrical with respect to the center point O, the pair of long sides L1 and L2 that are closest to each of the corners C1 ′ and C6 ′ are changed. On the other hand, the extraction electrodes 6L and 6M extend in a diagonally upward right direction or a diagonally downward left direction. In this case, since the external terminals can be formed longer in the direction of the base long side having a margin than the base short side in the range close to the base center point O, the solder joint area is expanded, and the joint strength is improved. Can be planned.

<Fourth Embodiment of the Present Invention>
A fourth embodiment of the present invention will be described with reference to FIG. The pair of external terminals 54 and 54 and the pair of extraction electrodes 6N and 6O in the present embodiment have the same configuration as that of the third embodiment (see FIG. 6) of the present invention. The difference from the third embodiment is that conductive bumps MB1 and LB1 having an area smaller than the area of the external terminals 54 and 54 are formed on the pair of external terminals 54 and 54 so as to protrude. The support bumps SB1 to SB4 are evenly arranged near the four corners of the outer bottom surface 200.

  In FIG. 10, a conductive bump (hereinafter abbreviated as a main bump) MB1 recedes from the outer peripheral edge of the external terminal 54 by a predetermined distance toward the center of the external terminal (inside). Formed). The predetermined distance is substantially constant, and is 0.06 mm in this embodiment. The predetermined dimension is an example, and is set in the range of more than 0.00 mm and less than 0.45 mm (preferably more than 0.06 mm and less than 0.12 mm). By setting within such a range, the stress on the outer periphery of the external terminal and the strain in the thickness direction of the external terminal can be alleviated. Thereby, generation | occurrence | production of a crack can be suppressed.

  As shown in FIG. 10, support bumps SB <b> 1 to SB <b> 4 are formed near the four corners of the base outer bottom surface 200. Since the support bumps SB1 to SB4 are evenly arranged outside the main bump MB1 so as to surround the pair of main bumps MB1 and MB1, it is possible to prevent the crystal resonator from being tilted during solder bonding to the external substrate. it can. Note that the formation positions of the support bumps are not necessarily in the vicinity of the four corners of the outer bottom surface of the base.

  The support bumps SB1 to SB4 are not electrically connected to the pair of pad electrodes (see FIG. 1) inside the base, and are in an electrically independent state. And it is not soldered to the external substrate. In addition, in order to prevent insulation failure between land patterns of the external substrate on which the crystal unit is mounted, support bumps made of an insulating material, or a structure in which the surface of a support bump made of a conductive material is covered with an insulating material Bumps may be used.

  The thickness (height) of the support bumps SB1 to SB4 is set to a thickness (height) equal to or greater than the total thickness (height) including the thickness of the external terminal 54 and the thickness of the main bump MB1. Yes. For example, by making the thickness of the support bump thicker (higher) than the total thickness of the external terminals and the main bump, a gap is created between the main bump and the land on the external substrate. Can be thicker. That is, the thickness of the solder under the main bump can be controlled by adjusting the thickness of the support bump and the thickness of the main bump.

<Fifth Embodiment of the Present Invention>
A fifth embodiment of the present invention will be described with reference to FIG. The pair of external terminals 55 and 55 and the pair of extraction electrodes 6P and 6Q in the present embodiment are the same as in the third embodiment (see FIG. 6) of the present invention except that a pair of main bumps MB2 and MB2 are formed. It has the same configuration. The difference from the third embodiment is that minute conductive bumps AB1 and AB1 are formed to protrude at the boundary between the pair of external terminals 54 and 54 and the extraction electrodes 6P and 6Q.

  According to the configuration shown in FIG. 11, auxiliary bumps AB1 (hereinafter abbreviated as auxiliary bumps) that are not integrally formed with the main bumps MB2 are formed at the outer corners where the distortion increases in the region of the external terminals. Therefore, it is possible to form a region where the strain is reduced in the region (gap) between the main bump MB2 and the auxiliary bump AB1. Thereby, while suppressing generation | occurrence | production of a crack, progress of a crack can be suppressed. As a result, the life of the crystal unit can be extended.

<Sixth Embodiment of the Present Invention>
A sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the auxiliary bump AB2 is formed so as to protrude in the region of the external terminal 56, and the main bump MB3 having a shape in which a part of the main bump is partially cut out so as to correspond to the shape of the auxiliary bump AB2. It is formed on the terminal 56. Other points are the same as those of the third embodiment of the present invention.

  In FIG. 12, the auxiliary bump AB2 having a circular shape in plan view is formed to protrude in the vicinity of the outer corner where distortion increases in the area of the external terminal, and is cut at a certain distance along the outer periphery of the auxiliary bump AB2. The missing main bump MB3 is formed on the external terminal 56 so as to protrude.

  According to the configuration shown in FIG. 12, as in the fifth embodiment, auxiliary bumps AB2 that are not integrally formed with the main bumps MB3 are formed in the vicinity of the outer corners where the distortion increases in the external terminal area. Therefore, it is possible to form an area where the strain is reduced in the area (gap) between the main bump MB3 and the auxiliary bump AB2. Thereby, while suppressing generation | occurrence | production of a crack, progress of a crack can be suppressed. As a result, the life of the crystal unit can be extended.

  In the present embodiment, a crystal resonator has been described as an example of the piezoelectric vibration device. However, the present invention can be applied not only to a piezoelectric resonator such as a crystal resonator but also to a piezoelectric oscillator.

  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.

DESCRIPTION OF SYMBOLS 1 Crystal resonator 2 Base 3 Lid 4 Crystal vibrating piece 5, 50-56 External terminal 6, 6A-6S Lead electrode L1, L2 Long side of base outer bottom surface W1, W2 Short side of base outer bottom surface

Claims (5)

A piezoelectric vibration device in which an external terminal provided on the outer bottom surface of the package is conductively bonded to an external substrate via solder,
The outer bottom surface of the package is substantially rectangular in plan view, and a pair of external terminals are disposed close to and symmetrically with respect to the center point of the outer bottom surface,
The external terminals have a substantially rectangular shape in plan view, and the corners of the external terminals of the rectangle have a set of corners from a set of corners that are point-symmetric with respect to the center point of the outer bottom surface of the package. A pair of lead-out electrodes are formed point-symmetrically with respect to the center of the package bottom surface toward one of the pair of long sides or the pair of short sides of the package exterior bottom surface that is recent in each of the parts A piezoelectric vibration device characterized by being made.   A pair of corner portions of the pair of external terminals is a corner portion on one end side of a side farthest from the center point of the package outer bottom surface among the four sides constituting the rectangle of each external terminal. The piezoelectric vibration device according to claim 1.   The pair of lead electrodes are either a set of long sides or a set of short sides of the outer terminal that is closest to each of the set of corners from each of the set of corners of the external terminal. The piezoelectric vibration device according to claim 1, wherein the piezoelectric vibration device is formed in an oblique direction toward a set of sides.   Of the two sides constituting each of the pair of corners of the external terminal, an angle formed by one side facing the side of the outer bottom surface of the package where a pair of extraction electrodes is not formed and the extending direction of the extraction electrode is 180. The piezoelectric vibration device according to claim 3, wherein the piezoelectric vibration device has an angle greater than or equal to degrees.   2. A conductive bump smaller than the external terminal is formed on the pair of external terminals so as to protrude from the outer peripheral edge of the external terminal toward the center of the external terminal. 4. The piezoelectric vibration device according to any one of 4 above.

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