JP2010268439A - Surface mounting crystal vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a surface mounting crystal vibrator from being damaged by falling shock. <P>SOLUTION: The surface mounting crystal vibrator has a base 2 made of crystal or glass including mounting terminals 5a, 5b in at least both end portions of a flat outer bottom surface and is configured by sealing a crystal piece in which at least an exciting electrode is formed. In the surface mounting crystal vibrator, recesses 9a, 9b are provided in both the end portions of the outer bottom surface of the base 2, the mounting terminals 5a, 5b are formed in the recesses 9a, 9b, and the crystal piece is composed of a crystal plate 1 for the vibrator which is surrounded with a holding frame as an outer circumferential portion and connected partially. The crystal plate 1 for the vibrator, the base 2 and a cover 3 are laminated while directly bonding their outer circumferential parts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has a technical field of a surface mount crystal resonator (hereinafter referred to as a surface mount resonator) using crystal or glass as a container material, and in particular, a stacked surface mount resonator using crystal (hereinafter referred to as a stack type). A vibrator).

(Background of the Invention)
Since the surface-mounted vibrator is small and light, it is built in, for example, various portable electronic devices as frequency and time reference sources. One of these is a laminated vibrator in which a quartz crystal plate for a vibrator, which is made of quartz, and a quartz plate for a base and a cover are laminated to reduce the thickness.

(Example of conventional technology)
FIG. 4 is a diagram for explaining a conventional example, in which FIG. 4 (a) is a mounting sectional view of a laminated vibrator on a set substrate, and FIG. 4 (b) is a plan view of a quartz crystal plate for the vibrator.

  The laminated vibrator is formed by laminating a quartz crystal plate 1, a base quartz plate 2, and a cover quartz plate 3. In the quartz crystal plate 1 for vibrator, for example, a holding frame 1c in which a tuning fork base 1a and a thin rod 1b are connected surrounds a tuning fork crystal piece 1d. The pair of tuning fork arms 1e in the tuning fork crystal piece 1d has a pair of excitation electrodes (not shown) that are electrically connected in common. The pair of excitation electrodes are connected to lead terminals 4 (ab) provided at both ends of the holding frame 1c through one main surface of the thin rod 1b.

  The base and cover crystal plates 2 and 3 are flat, for example, one main surface side is concave, and the thickness of the outer peripheral portion is larger than the central region. The base crystal plate 2 has mounting terminals 5 (ab) at both ends of the outer bottom surface, and is electrically connected to the lead terminals 4 (ab) of the crystal plate for vibrator 1 (holding frame 1 c) through the electrode through holes 6. To do. The mounting terminal 5 (ab) has an end face electrode for solder fillet on the outer surface, but is omitted here for convenience. The crystal plates 1, 2, and 3 for the vibrator, base, and cover are directly bonded at an interatomic level by siloxane bonds (Si-O-Si) or the like.

  Since these are of the laminated type in which the crystal plates 1, 2, and 3 for the vibrator, the base, and the cover are directly bonded, a thin surface mount vibrator having a particularly small thickness can be obtained. Incidentally, a surface-mounted vibrator having a planar outer shape of 3.2 × 1.5 mm and a thickness of 0.36 mm or less can be obtained. These are not limited to the tuning fork type, and the same applies to, for example, the quartz crystal plate 1 for an oscillator having an AT cut.

JP 2008-182665 A JP 2008-078791 A

(Problems of conventional technology)
However, the laminated vibrator having the above-described configuration has a problem of being damaged by an external impact (for example, a drop impact) after mounting on the set substrate 7 by, for example, solder reflow, particularly in the central region of the base crystal plate 2. It was. In the experiments by the present inventors, the larger the gap (spacing) d between the outer bottom surface of the laminated vibrator (base crystal plate 2) and the surface of the set substrate 7 is, the larger the thickness of the cream solder 8 etc. is, the more damage to external impact is. The frequency was found to be high.

  That is, assuming that an external force P due to a vertical dispersion vector is applied to the base crystal plate 2 due to external impact, for example, the larger the distance d, the more the bending (curvature) in the center region of the base crystal plate 2 becomes. Also grows. The quartz crystal plate for vibrator 1 is made of a brittle material having a lower strength than, for example, ceramic. Therefore, it has been found that the quartz crystal plate for vibrator 1 is broken by a bending force larger than its own strength (elastic limit), and the frequency of breakage increases as the distance d increases.

  These problems become more prominent because the base crystal plate 2 is more easily bent as the overall thickness of the laminated vibrator is smaller, particularly as the base crystal plate 2 is thinner. For example, the thickness of the outer peripheral portion of the base crystal plate 2 is 0.12 mm, and the thickness of the central region is 0.09 mm.

(Object of invention)
It is an object of the present invention to provide a surface mount vibrator including a laminated vibrator that improves impact resistance.

  The present invention has a base made of crystal or glass having mounting terminals at least at both ends of a flat outer bottom surface, and at least an excitation electrode is formed as shown in the claims (Claim 1). In the surface-mounted crystal resonator in which the crystal piece is hermetically sealed, recesses are provided at both ends of the outer bottom surface of the base, and the mounting terminals are formed in the recesses.

  With such a configuration, when the surface-mounted vibrator is mounted on the set substrate, for example, cream solder at the time of solder reflow is embedded in a recess on the bottom surface of the base. Accordingly, since the distance between the outer bottom surface of the base and the set substrate is reduced, the central region of the outer bottom surface of the base collides with the set substrate and stops even if there is an external impact (stop). As a result, it is possible to suppress the base from being bent and prevent the base from being damaged by the bending.

(Embodiment section)
According to a second aspect of the present invention, in the first aspect, the quartz crystal piece includes a quartz crystal plate for a vibrator that is surrounded by a holding frame as an outer peripheral portion and partially connected thereto, and the quartz crystal plate for the vibrator, the base, The cover is a laminated type in which the outer periphery is directly joined. As a result, a surface-mounted vibrator having a reduced thickness can be obtained.

  In the third aspect of the present invention, in the second aspect, the base and the cover each include a base crystal plate and a cover crystal plate having a concave portion as a crystal. As a result, all the quartz plates including the quartz plate for the vibrator are made of quartz, so that the expansion coefficient is the same, stress distortion due to thermal shock or the like is reduced, and vibration characteristics are improved. Since both the base crystal plate and the cover crystal plate have recesses, the resonator crystal plate can be formed in a simple flat plate shape to ensure a gap with the vibration region.

  In the fourth aspect of the present invention, in the third aspect, a shield electrode is formed on the bottom surface of the concave portion of the base crystal plate and the base cover. Thereby, EMI (electromagnetic wave interference) can be reduced and a change in the oscillation frequency can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a view of a laminated vibrator for explaining a first embodiment of the present invention, FIG. 1A is an external view, and FIG. It is a figure of the laminated vibrator explaining 2nd Embodiment of this invention, The figure (a) is sectional drawing, The figure (b) is an outer bottom view. It is sectional drawing of the surface mount vibrator explaining other embodiment of the present invention. FIG. 2A is a diagram of a laminated vibrator for explaining a conventional example, in which FIG. 1A is a mounting sectional view with respect to a set substrate, and FIG. 2B is a plan view of a quartz crystal plate for vibrator.

(First embodiment)
Hereinafter, a surface-mounted vibrator as one embodiment of the present invention will be described with reference to FIG. 1 (outside view, mounting cross section). In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.

  The surface-mounted vibrator is also the above-described laminated vibrator, and is formed by directly joining the outer peripheral portions of the vibrator, base, and cover crystal plates 1, 2, and 3. The quartz crystal plate 1 for a vibrator surrounds a tuning fork crystal piece 1d connected to a part of the tuning fork base 1a by a holding frame 1c. The base and cover crystal plates 2 and 3 are both concave to increase the thickness of the outer peripheral portion. Both ends of the outer bottom surface of the base crystal plate 2 have mounting terminals 5 (ab). The planar outer shape here is, for example, 3.2 × 1.5 mm as described above, the thickness is 0.36 mm, and the thickness of the base crystal plate 2 is 0.12 mm.

  In this embodiment, recesses 9 (ab) having an open outer peripheral side are provided at both ends of the outer bottom surface of the base crystal plate 2. And the mounting terminal 5 (ab) is formed in the bottom face and inner peripheral side surface of the hollow 9 (ab). The mounting terminal 5 (ab) is electrically connected to the lead terminal 4 (ab) of the crystal plate for vibrator 1 through the electrode through-hole 6 as described above.

  The external shape processing including these depressions 9 (ab) and the electrode patterns such as the mounting terminals 5 (ab) and the electrode through holes 6 are formed in a state of a crystal wafer (not shown) by, for example, photolithography or wet etching. Then, after being directly bonded to the crystal wafer 1 for the vibrator and the crystal wafers for the base and cover crystal plates 2 and 3, it is divided into individual laminated vibrators.

  In such a case, when the laminated vibrator is mounted on the set substrate 7 by solder reflow, the cream solder 8 applied to the circuit terminals of the set substrate 7 is applied to the outer bottom surface on which the mounting terminals 5 (ab) are formed. It is embedded (filled) in the depression 9 (ab) at both ends. Therefore, the distance d between the outer bottom surface of the laminated vibrator including the mounting terminal 5 (ab), the circuit terminal 10 (ab), and the solder 8 and the surface of the set substrate 7 can be made smaller than in the conventional example.

  As a result, even if an external impact is applied to the laminated vibrator, even if an external force P from the vertical direction due to these dispersion vectors acts on the base crystal plate 2, the central region of the base crystal plate 2 is set substrate. Stop at 7's surface. Therefore, it is possible to prevent the base crystal plate 2 from being bent and to prevent damage in the central region due to bending.

(Second Embodiment)
FIGS. 2A and 2B are views of a laminated vibrator for explaining the second embodiment of the present embodiment. FIG. 2A is a sectional view thereof, and FIG. 2B is a bottom view of the same. In addition, description of the same part as previous embodiment is abbreviate | omitted or simplified.

  In the second embodiment, as described above, the vibratory crystal plate 1 and the base and cover crystal plates 2 and 3 are formed into a laminated vibrator by direct bonding. Here, the shield electrode 11 (ab) is formed on the bottom surfaces of the concave portions of the base and cover crystal plates 2 and 3. Then, the mounting terminals 5 (abcd) are provided at the four corners of the outer bottom surface of the base crystal plate 2.

  Of the four corner mounting terminals 5 (abcd), the diagonally facing pair of diagonal mounting terminals 5 (ab) is connected to the lead-out terminals 4 (ab) of the tuning-fork crystal piece 1d in the same way as described above. Electrically connected by etc. The other pair of diagonal mounting terminals 5 (cd) are electrically connected to the shield electrode 11 (ab) by an electrode through hole (not shown). Even in this case, the recesses 9 (abcd) are provided in the four corners where the mounting terminals 5 (abcd) are provided, and the mounting terminals 5 (abcd) are formed in the recesses 9 (abcd).

  Even in such a configuration, as in the first embodiment, the cream solder 8 is filled in the recess 9 (abcd) when mounted on the set substrate 7, and the outer bottom surface of the multilayer vibrator and the set substrate are filled. Since the gap with the surface of 7 is reduced, the base crystal plate 2 can be prevented from being damaged.

  In this example, since the shield electrode 11 (ab) is provided, EMI (electromagnetic interference) is reduced. Further, when a crystal oscillator is configured, for example, the stray capacitance between the excitation electrode of the tuning-fork crystal piece 1d and the set substrate 7 is reduced to prevent a change in oscillation frequency.

  In the first and second embodiments, the base and cover crystal plates 2 and 3 can be applied even when, for example, glass having a strength lower than that of ceramic is used. In this case, quartz has anisotropy in etching rate, whereas glass is isotropic. Therefore, when manufactured by etching, the productivity can be increased because it is cheaper than quartz.

  As glass, borosilicate glass that is generally cheaper than quartz is often used. Here, the Knoop hardness of the borosilicate glass is 590 kg / mm. ² It is. On the other hand, the Knoop hardness of quartz is 710-790 km / mm, which is higher than that of borosilicate glass. ² It is. Therefore, when using the crystal plates 2 and 3 for the base and the cover made of crystal, the size and the height can be reduced while securing the strength of the laminated vibrator as compared with the case of using the borosilicate glass. It becomes possible.

(Other matters)
In the above-described embodiment, the surface-mounted vibrator has been described as a laminated vibrator. However, for example, the surface-mounted vibrator shown in FIG. 3 can also be applied. That is, a pedestal 13 is provided on the inner bottom surface of a concave base 12 made of crystal or glass having mounting terminals 5 (ab) on the outer bottom surface, and the tuning fork base 1a of the tuning fork crystal piece 1d is fixed, and the opening end surface is covered with the cover 14. The same can be applied to the case of sealing with.

  In this case, the bottom wall layer 12a and the frame wall layer 12b are directly joined to the concave base 12, for example. Further, the cover 14 is joined to the opening end surface by, for example, seam welding as the metal, or by resin sealing or glass sealing as the metal or insulator. The present invention can be applied to a case where a material made of a brittle material having a strength lower than that of generally provided alumina ceramic (Al 2 O 3) is used as a base, and among these, claim 1 specifies crystal and glass. ing.

  1 crystal plate for vibrator, 2 crystal plate for base, 3 crystal plate for cover, 4 lead terminal, 5 mounting terminal, 6 electrode through hole, 7 set substrate, 8 solder, 9 recess, 10 circuit terminal, 11 shield electrode, 12 base, 13 base, 14 cover.

Claims (4)

  A surface-mount crystal resonator having a base made of crystal or glass having mounting terminals on at least both ends of a flat outer bottom surface, wherein at least a crystal piece on which an excitation electrode is formed is hermetically sealed. A surface-mounted crystal resonator, wherein recesses are provided at both ends of the outer bottom surface, and the mounting terminals are formed in the recesses.   2. The crystal unit according to claim 1, wherein the crystal piece is composed of a crystal plate for a vibrator that is surrounded by a holding frame as an outer peripheral portion and is partially connected, and the crystal plate for the vibrator, the base, and the cover have an outer peripheral portion directly. A surface-mount crystal unit with a laminated structure.   3. The surface-mount crystal resonator according to claim 2, wherein the base and the cover are both a base crystal plate and a cover crystal plate each having a concave portion as a crystal.   4. The surface-mount crystal resonator according to claim 3, wherein a shield electrode is formed on a bottom surface of the concave portion of the base crystal plate and the base cover.