Vibration device

Abstract

To provide a vibration device which is hermetically sealed by seam welding and has excellent quality.SOLUTION: The vibration device 1 includes a base 4 having a first surface and a recess 6 having an opening on the first surface, and is seam-welded to the first surface of the base 4. A lid 5 that closes an opening of the recessed portion 6, and a resonator element accommodated in the recessed portion 6, in which in a plan view, the lid 5 has a rectangular shape in which four corner portions have an arc shape, and is disposed inside an outer edge of the first surface, the opening of the recess 6 has a rectangular shape with four arc-shaped corners and is disposed inside the outer edge of the lid 5, and when the curvature radius at the corner of the lid 5 is defined as r1 and the curvature radius at the corner of the recess 6 is defined as r2, the relationship of r1> r2 * 2 is satisfied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vibration device. [Background technology]

[0002] In a resonator device such as a quartz crystal resonator, a resonator element is generally housed in a package. The package includes a base on which electronic components are mounted and a lid joined to the base, defining a space between them to house the resonator element. Seam welding is used to join the base and the lid, as disclosed in, for example, Patent Document 1. In Patent Document 1, a metal ring provided on the open end surface of a ceramic container is joined to a metal cover by seam welding. Seam welding is performed by contacting a pair of opposing edges of the metal cover with an electrode roller and moving it in a straight line, welding two pairs of edges sequentially. Both the metal ring and the metal cover have arc-shaped curvatures at the four corners of their peripheries. The outer shape of the metal cover is smaller than that of the metal ring. Generally, the welds on the first pair of edges and the welds on the second pair of edges overlap at the corners of the metal cover to form an overlap, thereby welding the entire circumference of the metal cover and hermetically sealing the package. Furthermore, in recent years, there has been an increasing demand for miniaturization of electronic devices, and there is also an increasing demand for miniaturization of vibration devices used in electronic devices while maintaining high accuracy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-260644 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the vibration device of Patent Document 1, the radius of curvature of the corners of the metal cover is small, making it impossible to ensure a sufficient overlap area for welding. If the radius of curvature of the metal cover were increased, it would be possible to ensure a sufficient overlap area for welding, but the welded area would become larger, resulting in an increased amount of gas being generated during welding. If the amount of gas increases, the degree of vacuum inside the sealed package would decrease, which could degrade the quality of the vibration device. [Means for solving the problem]

[0005] A vibration device according to an application example of the present invention comprises a base having a first surface and a recess having an opening formed on the first surface, a lid body seam-welded to the first surface of the base and covering the opening of the recess, and a vibration element housed in the recess, wherein, in a planar view, the lid body is rectangular with four arc-shaped corners and is positioned inside the outer edge of the first surface, the opening of the recess is rectangular with four arc-shaped corners and is positioned inside the outer edge of the lid body, and when the radius of curvature at the corner of the lid body is r1 and the radius of curvature at the corner of the recess is r2, the relationship r1>r2×2 is satisfied. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a plan view illustrating a configuration of a vibration device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 2 is an enlarged view of the portion enclosed by the circle B in FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 10 is a side cross-sectional view showing the configuration of a vibration device according to a second embodiment. [Figure 7] FIG. 2 is a schematic diagram illustrating seam welding. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Note that the dimensions or scale of each part in the drawings may differ from the actual dimensions, and some parts are shown schematically to facilitate understanding. For ease of explanation, each drawing illustrates three mutually orthogonal axes: the X-axis, the Y-axis, and the Z-axis. The direction along the X-axis is referred to as the "X-axis direction," the direction along the Y-axis as the "Y-axis direction," and the direction along the Z-axis as the "Z-axis direction." The arrowed side of each axis is also referred to as the "plus side," and the opposite side as the "negative side."

[0008] 1. First embodiment The first embodiment will be described in detail below with reference to the drawings.

[0009] FIG. 1 is a plan view showing the configuration of a resonator device 1 according to a first embodiment, with a lid 5 removed. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. The resonator device 1 is a surface-mounted component in which a resonator element 2 is packaged. The resonator device 1 has a resonator element 2 and a package 3, and the resonator element 2 is housed in an internal space S of the package 3. The package 3 has a base 4 and a lid 5, and the base 4 is a box-shaped member in which a recess 6 is formed. The base 4 and the lid 5 are joined by seam welding, which will be described later, thereby defining an internal space S of the package 3. A vacuum state is maintained in the internal space S.

[0010] The lid body 5 is disposed on the +Z direction side of the base 4. When viewed from above in the +Z direction, the base 4 is rectangular with long sides along the X axis and short sides along the Y axis. When viewed from above in the +Z direction, the lid body 5 is rectangular with long sides along the X axis and short sides along the Y axis, and has four corners. The long sides of the base 4 and the long sides of the lid body 5 extend in the same direction. The short sides also extend in the same direction.

[0011] The base 4 has a bottom 10 and a frame-shaped frame 20 disposed on the bottom 10. The frame 20 is disposed surrounding a main surface 62 of the bottom 10. The recess 6 is composed of the main surface 62 and an inner surface 63 of the frame 20. The shape of the recess 6 is rectangular when viewed from above in the +Z direction, and has four corners.

[0012] The frame 20 has a base 21 disposed on the bottom 10 side, and an annular metal ring 30 made of a metal material disposed on the opposite side to the bottom 10.

[0013] The metal ring 30 forms the opening of the recess 6, and an end face 61 of the metal ring 30 opposite to the face on the bottom 10 side has the opening of the recess 6. The end face 61 is joined to the lid body 5, which will be described later, by seam welding. That is, the end face 61 is a joining surface joined to the lid body 5. The end face 61 corresponds to the first surface. The main surface 62 corresponds to the second surface.

[0014] The material of the bottom portion 10 and the base portion 21 is not particularly limited, but various ceramics such as alumina are used as insulating materials.

[0015] The bottom portion 10 has an external terminal 52 on the surface opposite to the surface on which the frame portion 20 is disposed.

[0016] In plan view from the +Z direction, the opening of the recess 6 is rectangular and has four corners. The opening of the recess 6 is located inside the outer edge of the lid 5. The four corners are arc-shaped in plan view.

[0017] Examples of the material of the metal ring 30 include Kovar, 42 alloy, stainless steel, etc. Furthermore, the surface of the metal ring 30 is appropriately coated with a film of, for example, nickel (Ni) or gold (Au).

[0018] The lid 5 is a flat metal member that closes the opening of the recess 6. The recess 6 and the lid 5 define an internal space S. The lid 5 is disposed inside the outer edge of the end face 61. The four corners of the lid 5 are arc-shaped in plan view. The size of the central angle of the arc is not particularly limited, but is, for example, approximately 90 degrees. The lid 5 may be made of a material that can be seam welded to the base 4, such as Kovar, 42 alloy, or stainless steel.

[0019] The resonator element 2 is fixed to the main surface 62 via a support member 50. The resonator element 2 is, but is not particularly limited to, a quartz crystal element, for example. In this case, the support member 50 is a conductive adhesive material, and is electrically connected to an external terminal 52 via an internal terminal 51 provided on the main surface 62.

[0020] In addition, instead of a quartz crystal element, for example, lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate (PZT), lithium tetraborate (Li2B4O7), langasite (La3Ga5SiO 14 ), potassium niobate (KNbO3), gallium phosphate (GaPO4), gallium arsenide (GaAs), aluminum nitride (AlN), zinc oxide (ZnO, Zn2O3), barium titanate (BaTiO3), lead titanate (PbPO3), potassium sodium niobate ((K,Na)NbO3), bismuth ferrite (BiFeO3), sodium niobate (NaNbO3), bismuth titanate (Bi4Ti3O 12 ), bismuth sodium titanate (Na 0.5 Bi 0.5 Various piezoelectric substrates such as TiO3 may be used, or a substrate other than a piezoelectric substrate such as a silicon substrate may be used.

[0021] Here, seam welding will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining an outline of seam welding. Note that the details of seam welding described here are not particularly limited to this embodiment.

[0022] First, the principle of seam welding will be explained. Similar to resistance welding, seam welding uses pressure and electricity to weld the base 4 and lid 5 together. First, the lid 5 is placed on the base 4, and a pair of electrodes called roller electrodes 100 is placed on top of the lid 5. Electricity is passed through the roller electrodes 100 between the base 4 and lid 5. Joule heat is generated at the contact point between the roller electrodes 100 and the lid 5 due to high resistance. In seam welding, this heat welds the base 4 and lid 5 together. The roller electrode 100 rolls along the edge of the lid 5 from end to end while current is applied. Each time current is applied, the base 4 and lid 5 are partially welded together. As the roller electrode 100 moves along the edge of the lid 5, current is continuously applied, connecting the welded areas.

[0023] Next, the roller electrode 100 will be described. Each of the pair of roller electrodes 100 has a conical shape. The pair of roller electrodes 100 is arranged so that the apexes of the cones face each other. The roller electrode 100 rolls on the lid body 5 while pressing against the lid body 5. As described above, the outer edge of the lid body 5 is composed of straight portions and corners. The width of the lid body 5 in a direction perpendicular to the direction in which the roller electrode 100 travels is smaller at the corners than at the straight portions. Therefore, the position of the roller electrode 100 in contact with the lid body 5 in the rotation axis direction is closer to the apex of the cone when the roller electrode 100 is located at the corner than when it is located at the straight portion.

[0024] Next, the seam welding method will be described. Seam welding includes a step of welding the sides of the lid 5 along the X-axis and a step of welding the sides along the Y-axis. The order in which these two steps are performed is not particularly limited. In each step, the straight portions of the sides and parts of the corners connecting both ends of the straight portions are welded. By performing welding in two steps, the areas welded from two directions can be connected at the corners. In this way, welding is performed without gaps around the entire periphery of the opening of the recess 6, thereby hermetically sealing the base 4 and the lid 5.

[0025] The atmosphere in which seam welding is performed is not particularly limited, but it is preferable that, for example, the air in the recess 6 is replaced with an inert gas such as nitrogen or argon, and the pressure inside the recess 6 is reduced relative to atmospheric pressure, particularly a vacuum state. This makes it possible to provide a vibration device 1 that maintains stable performance over a long period of time.

[0026] The external dimensions of the resonator device 1 according to this embodiment will be described with reference to Figures 1 to 3. Figure 3 is an enlarged view of the area surrounded by a circular frame B in Figure 1, with the resonator element 2, the support member 50, and the internal terminals 51 omitted.

[0027] As described above, in a plan view from the +Z direction, the outer edge of the lid 5 is positioned more inward than the outer edge of the base 4. Therefore, the external dimensions of the vibration device 1 in a plan view from the +Z direction can be explained by replacing them with the external dimensions of the base 4 in a plan view from the +Z direction.

[0028] The width dimension of the base 4 in the long side direction is designated as Xp, and the width dimension in the short side direction is designated as Yp. Preferably, Xp is 1.9 to 2.1 mm, and Yp is 1.5 to 1.7 mm, for example. Since the size of the resonation device 1 is approximately 2.0 mm × approximately 1.6 mm, this is sometimes referred to as 2016 size. Alternatively, Xp may be 1.9 to 2.1 mm, and Yp may be 1.1 to 1.3 mm. This may also be referred to as 2012 size. Alternatively, Xp may be 1.5 to 1.7 mm, and Yp may be 0.9 to 1.1 mm. This may also be referred to as 1610 size. Note that in the present embodiment, for the sake of simplicity, the external dimensions of the resonation device 1 may be referred to as 2016 size, 2012 size, or 1610 size, and these sizes may also be referred to as "package size."

[0029] The width dimension of the lid 5 in the long-side direction is defined as X1, and the width dimension in the short-side direction is defined as Y1. Furthermore, the radius of curvature of the arc-shaped corner of the lid 5 in a plan view from the +Z direction is defined as r1. In the above-mentioned 2016 size package 3, X1 is 1.89 to 1.95 mm, Y1 is 1.49 to 1.55 mm, and r1 is 0.15 to 0.25 mm. In the above-mentioned 2012 size package 3, X1 is 1.89 to 1.95 mm, Y1 is 1.09 to 1.15 mm, and r1 is 0.15 to 0.25 mm. In the above-mentioned 1610 size package 3, X1 is 1.49 to 1.55 mm, Y1 is 0.89 to 0.95 mm, and r1 is 0.15 to 0.25 mm.

[0030] In the recess 6 of the base 4, the width dimension of the opening along the X-axis direction is defined as X2, and the width dimension of the opening along the Y-axis direction is defined as Y2. Furthermore, the distance along the Z-axis direction from the main surface 62 to the lid 5 is defined as D. In the above-mentioned 2016 size package 3, X2 is 1.75 mm, Y2 is 1.25 mm, and D is 0.42 mm. In this case, the volume of the internal space S is 0.92 mm. 3 In the above-mentioned 2012 size package 3, X2 is 1.75 mm, Y2 is 0.85 mm, and D is 0.42 mm. In this case, the volume of the internal space S is 0.62 mm. 3 In the above-mentioned 1610 size package 3, X2 is 1.35 mm, Y2 is 0.75 mm, and D is 0.33 mm. In this case, the volume of the internal space S is 0.34 mm 3 Note that X2, Y2, and D are maximum values ​​that include manufacturing variations.

[0031] Furthermore, the minimum volume of the internal space S will be described for the 1610 size package 3, which is the smallest of the three sizes of package 3 described in this embodiment. If X2, Y2, and D are minimum values ​​including manufacturing variations, then for the 1610 size package 3, X2 is 1.25 mm, Y2 is 0.65 mm, and D is 0.23 mm, and the volume of the internal space S is 0.19 mm. 3 is.

[0032] In a plan view from the +Z direction, let the arc radius of curvature at the corner of the recess 6 be r2. In the package 3 of size 2016, r2 is 0.05 to 0.15 mm. In the package 3 of size 2012, r2 is 0.05 to 0.15 mm. In the package 3 of size 1610, r2 is 0.05 to 0.15 mm.

[0033] Next, details of the corner of the lid body 5 and the corner of the recess 6 will be described. In the vibration device 1 according to the present embodiment, r1 and r2 satisfy the relationship of r1 > r2 × 2. That is, the relationship of r2 < r1 / 2 is satisfied, and r2 is smaller than half of r1. The values of r1 and r2 are not limited, but for each package size, for example, in the case of the package 3 of size 2016, r1 is 0.22 mm and r2 is 0.10 mm; in the case of the package 3 of size 2012, r1 is 0.25 mm and r2 is 0.12 mm; in the case of the package 3 of size 1610, r1 is 0.20 mm and r2 is 0.08 mm, etc. By satisfying the relationship of the above formula between r1 and r2, while sufficiently securing the area of the welding overlap portion, it is possible to suppress a decrease in the degree of vacuum inside the package 3 after sealing and maintain the quality as the vibration device 1. The reason will be described in detail below using FIGS. 4 and 5.

[0034] FIG. 4 shows the welding state after welding the side along the X-axis direction of the lid body 5. FIG. 5 shows the welding state after subsequently welding the side along the Y-axis direction of the lid body 5 after performing the welding shown in FIG. 4. As shown in FIG. 4, by increasing r1, the distance that the roller electrode 100 wraps around from the straight portion to the corner of the lid body 5 can be increased. As a result, the welded portion M1, which is the welded area, does not stay in the straight portion but is formed up to a part of the corner.

[0035] 5, even when the edge of the cover 5 along the Y-axis direction is welded, the welded region, welded portion M2, is formed up to a part of the corner. In this way, by welding the two straight portions connecting the corner, it becomes possible to overlap the two welded portions M1 and M2 at the corner, and an overlapping portion MS can be formed where the welded regions are overlapped.

[0036] An overlapping portion MS is formed at each of the four corners of the lid 5. This improves the reliability of welding at the corners of the lid 5, and allows welding to be performed without gaps around the entire periphery of the opening in the base 4. This seals the recess 6, preventing air from entering from the outside after the sealing operation and reducing the degree of vacuum in the internal space S.

[0037] Furthermore, because r2 is smaller than half of r1, the width of the weld in the direction from the corner of the lid 5 to the corner of the recess 6 can be limited in plan view from the +Z direction. This prevents the welded area from becoming unnecessarily large, and prevents the amount of gas generated by welding from increasing. Therefore, it is possible to prevent an increase in the amount of gas trapped in the internal space S due to sealing.

[0038] By doing so, it is possible to ensure a sufficient area for the overlapping welds, while suppressing a decrease in the degree of vacuum in the internal space S after sealing, and to maintain the quality of the vibration device 1.

[0039] Furthermore, when r2 is smaller than 0.15 mm, the relationship r1-r2≧0.15 mm is satisfied. This makes it possible to reduce the width of the weld in the direction from the corner toward the recess 6 in a plan view from the +Z direction while ensuring a sufficient overlapping area of ​​the weld. This further prevents a decrease in the degree of vacuum in the internal space S after sealing.

[0040] Furthermore, when viewed from above in the +Z direction, the distance between the corner of the lid 5 and the corner of the recess 6 is defined as L, and L is within a range of 0.02 mm or more and 0.08 mm or less. This ensures airtightness after welding and further reduces gas generation.

[0041] A package 3 of 2016 size or a package 3 with Xp and Yp smaller than the 2016 size also has a smaller volume inside the recess 6. That is, in the vibration device 1 according to this embodiment, it is preferable that the base 4 has a width dimension Xp in the long side direction of 2.1 mm or less and a width dimension Yp in the short side direction of 1.7 mm or less.

[0042] In this way, as Xp and Yp decrease, the volume inside the recess 6 also decreases. Even if the amount of gas generated by welding remains constant, the reduced volume reduces the degree of vacuum in the internal space S partitioned by the recess 6 and the lid 5. If the degree of vacuum decreases, friction occurs between the resonator element 2 and the gas molecules trapped in the internal space S when the resonator element 2 performs mechanical vibration, impeding the mechanical vibration. This impediment to mechanical vibration reduces the quality of the resonator device 1.

[0043] As the resonator device 1 becomes smaller, the resonator element 2 housed therein also becomes smaller, and the resonator element 2 becomes more sensitive to the degree of vacuum. Therefore, a decrease in the degree of vacuum significantly reduces the quality of the resonator device 1. Therefore, a resonator device 1 having a small base 4 with Xp of 2.1 mm or less and Yp of 1.7 mm or less has a significant effect of reducing the influence of gas. Note that in this embodiment, the outer edge of the base 4 is not limited to a rectangle, and may be, for example, a square.

[0044] In the resonator device 1 according to this embodiment, the volume of the internal space S in which the resonator element 2 is housed, that is, the space defined by the recess 6 and the lid 5, is 0.92 mm 3 In this case, the effect of reducing the influence of gas is significant, as in the case of the volume of 0.92 mm 3is an example of the volume when the package size is 2016 size, but is not limited to this and may be a package size other than 2016 size.

[0045] Furthermore, the volume of the internal space S is 0.62 mm 3 In this case, the effect of reducing the influence of gas becomes more pronounced, as in the case described above. 3 is an example of a 2012 size package size, but is not limited to this and may be a package size other than the 2012 size.

[0046] In this embodiment, the values ​​of the dimensions are described, but these values ​​may be not only actual measured values ​​but also design values.

[0047] Furthermore, although an example has been described in which the resonator element 2 is housed in the package 3, electronic components may be housed in addition to the resonator element 2. Although not limited thereto, for example, an IC chip as an oscillation circuit or a sensor element may be housed.

[0048] In this embodiment, the end surface 61 of the metal ring 30 is the first surface, but the end surface on the +Z direction side of the base 21 of the base 4 may be the first surface without using a metal ring. In that case, the end surface on the +Z direction side of the base 21 is metallized and the lid body 5 is seam-welded.

[0049] 2. Second embodiment A resonation device 1a according to a second embodiment will be described with reference to Fig. 6. In Fig. 6, the same components as those in the above-described embodiment are denoted by the same reference numerals.

[0050] 6 is a side cross-sectional view showing the configuration of a resonator device 1a according to the second embodiment. The configuration of the resonator device 1a differs from the configuration of the resonator device 1 in that a thick, annular metal ring 30a is disposed in the frame portion that forms the recess 6a together with the bottom portion 10a, i.e., the portion corresponding to the frame portion 20 in the first embodiment, without including an insulating material.

[0051] The base 4a includes a bottom portion 10a made of an insulating material and having a main surface 62a, and a metal ring 30a made of a metal material and having a through-hole penetrating the front and back surfaces. In this embodiment, the bottom portion 10a is an example of a substrate portion, and the metal ring 30a is an example of an annular portion. The main surface 62a corresponds to the second surface. One of the front and back surfaces of the metal ring 30a is joined to the main surface 62a of the bottom portion 10, and the other surface 61a is joined to the lid 5. The main surface 62a exposed in the through-hole of the metal ring 30a and an inner surface 63a of the metal ring 30a form a recess 6a. In other words, the other surface 61a corresponds to the first surface in the first embodiment.

[0052] With this configuration, compared to when the frame portion of the base 4a is configured to include an insulating material, the metal ring 30a can serve as the entire frame portion, and there is no need to use an insulating material for the frame portion, thereby making it possible to reduce the height of the vibration device 1a.

[0053] The above description is based on the embodiment of the vibration device 1, 1a, but the present embodiment is not limited to this, and the configuration of each part can be replaced with any configuration having the same function. In addition, any other components may be added to the present embodiment. In addition, each embodiment may be combined as appropriate. [Explanation of symbols]

[0054] 1,1a...vibration device, 2...vibration element, 3...package, 4,4a...base, 5...lid body, 6,6a...recess, 10,10a...bottom, 20...frame, 21...base, 30,30a...metal ring, 50...support member, 51...internal terminal, 52...external terminal, 61...end surface, 61a...surface, 62,62a...main surface, 63,63a...inner surface, 100...roller electrode, D...depth, L...distance, M1,M2...weld, MS...overlap, S...internal space, X1,X2,Xp,Y1,Y2,Yp...width dimension.

Claims

1. a base having a first surface, the first surface having a recess formed therein with an opening; a cover that is seam-welded to the first surface of the base and closes the opening of the recess; a vibrating element accommodated in the recess, In plan view, the cover has a rectangular shape with four arc-shaped corners, and is disposed inside the outer edge of the first surface; The opening of the recess has a rectangular shape with four arc-shaped corners, and is disposed inside the outer edge of the lid. When the radius of curvature at the corner of the lid is r1 and the radius of curvature at the corner of the recess is r2, r1>r2×2 A vibration device characterized by satisfying the relationship:

2. When r2 is smaller than 0.15 mm, r1-r2≧0.15mm The vibration device according to claim 1 , wherein the following relationship is satisfied:

3. The vibration device according to claim 1 , wherein the distance between the corners is within a range of 0.02 mm to 0.08 mm in plan view.

4. In a plan view, the outer edge of the base is a rectangle having long sides and short sides, The vibration device according to claim 1 , wherein the base has a width dimension of 2.1 mm or less in the long side direction and a width dimension of 1.7 mm or less in the short side direction.

5. The volume of the space defined by the recess and the lid and accommodating the vibrating element is 0.92 mm 3 3. The vibration device according to claim 1, wherein:

6. The volume of the space is 0.62 mm 3 6. The vibration device according to claim 5, wherein:

7. the base includes a substrate portion made of an insulating material and having a second surface, and an annular portion made of a metal material and having a through hole penetrating from the front to the back surface, one of the front and back surfaces of the annular portion is joined to the second surface, and the other surface is the first surface; The vibration device according to claim 1 , wherein the recess is configured by the second surface exposed in the through hole of the annular portion and an inner surface of the through hole.

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