JP5142668B2 - Crystal device for surface mounting - Google Patents

Description

  The present invention relates to a crystal device for surface mounting, and more particularly to a crystal terminal of a container body that accommodates a plurality of crystal pieces having different planar external shapes.

(Background of the Invention)
Surface mount crystal devices such as crystal resonators (hereinafter referred to as surface mount resonators) are small and light, so they can be used as frequency and time reference sources in portable electronic devices such as mobile phones. Built in. In recent years, the planar external shape of the surface-mounted vibrator (container main body) has also been standardized as, for example, 5 × 3.2 mm, 3.2 × 2.5 mm, and the like, and various crystal pieces corresponding to the application and function are accommodated in these container main bodies.

(Example of conventional technology)
4A and 4B are diagrams for explaining a conventional example. FIG. 4A is a cross-sectional view of a surface mount vibrator, FIG. 4B is a plan view excluding a cover, and FIG. 4C is a plan view of a crystal piece. It is.

  The surface-mount vibrator accommodates the crystal piece 2 in a rectangular container body 1 in a plan view made into a concave shape made of laminated ceramic. The inner bottom surface of the container main body 1 has crystal terminals 3 (not shown) on both sides of one end in the length direction, and extends as an external terminal 4 through, for example, a pair of diagonal portions through the laminated surface. And the metal cover 5 by seam welding is joined to the opening end surface of the container main body 1, for example, and the crystal piece 2 is hermetically sealed. The other pair of diagonal portions of the container body 1 have external terminals 4 as ground terminals electrically connected to the metal cover 5.

  The crystal piece 2 is, for example, a rectangular AT cut, and has a vibration frequency inversely proportional to the thickness as a thickness-shear vibration state. In general, when the vibration frequency is 26 MHz or more, for example, the crystal piece 2 has a flat plate shape, and in a lower frequency band below this, end face processing (bevel or convex) is performed to confine the vibration energy in the central region and reduce the crystal impedance (CI), for example. Made. In the figure, the end face processed crystal piece is the target.

  In these cases, the thickness becomes smaller as the vibration frequency is higher, and accordingly, the planar outer shape becomes smaller. On the contrary, since the thickness is larger for low frequency use, the planar outer shape is also larger. In the case of mass production, the end face processing is generally performed by putting a large number of crystal pieces 2 together with an abrasive into a cylindrical or spherical hollow container. Then, as the hollow container rotates, the outer periphery of the crystal piece 2 is processed into a curved surface that follows the inner periphery of the hollow container.

  In these cases, a curved inclined surface is formed not only in the long side direction but also in the short side direction of the crystal piece 2. Further, the four corners of the crystal piece in plan view are also processed into an arc shape (curved surface). In short, the crystal piece 2 has a curved inclined portion whose outer periphery in the length and width directions is gradually narrowed and the thickness is gradually reduced in plan view. The thickness of the inclined portion at the corner portion of the outer peripheral portion is substantially the same in the direction in which the corner portion is obliquely crossed. The thickness of the crystal piece 2 is a contour line similar to the outline of the crystal piece, as indicated by a thin line in FIG. 5 (plan view).

  Excitation electrodes 6 a are provided on both main surfaces of the crystal piece 2, and extraction electrodes 6 b are extended on both sides of one end. The extraction electrode 6b is formed by folding back to the other main surface. Then, both sides of one end portion of the crystal piece 2 from which the extraction electrode 6 b extends are fixed by the conductive adhesive 7. The conductive adhesive 7 is applied on the crystal terminal 3 in advance as a thermosetting type (undercoating), for example. Then, both ends of the crystal piece 2 are placed on the conductive adhesive 7 and then cured by heating. Alternatively, the conductive adhesive 7 is also applied from the upper surfaces on both sides of one end of the crystal piece 2 (overcoating) and cured by heating.

  In these cases, the quartz terminal 3 on the inner bottom surface of the container body 1 is printed with, for example, W (tungsten) or Mo (molybdenum) twice, for example, to increase the height (thickness) of the quartz terminal 3. These are integrally fired together with the container body 1 and then plated with Ni (nickel) and Au (gold). In the figure, the crystal terminal is shown as one layer for convenience.

  Thereby, when both ends of the one end portion of the crystal piece 2 are fixed to the crystal terminal 3, the center portion in the short side direction having a large thickness is prevented from coming into contact with the inner bottom surface of the container body 1 by the end face processing. Usually, the pillow part 8 is provided in the other end side of the container main body 1 and the other end part of the crystal piece 2 is placed to prevent the central part having a large thickness in the long side direction from contacting the inner bottom surface. Since the inner bottom surface is curved by the warp of the container body 1, these are effective even if the crystal piece 2 is flat.

Furthermore, each crystal terminal 3 is made longer in the width direction and corresponds to various crystal pieces 2 having different dimensions in the width direction. As described above, the dimension in the width direction corresponds to the thickness, and is smaller as the flat plate has a higher high frequency with a smaller thickness, and is larger as the low frequency with a larger thickness requiring end face processing. As a result, the container body 1 is made common to the various crystal pieces 2 having different width dimensions, thereby increasing the productivity.
Japanese Patent Laid-Open No. 2003-3068

(Problems of conventional technology)
However, in the surface-mounted resonator having the above configuration, although the container body 1 is shared in correspondence with the crystal pieces 2 having different width directions, the crystal piece 2 for the low frequency that has been particularly end-face processed (bevel or convex) is used. There is a problem that the fixing strength is low and the so-called impact resistance property of peeling against impact is lacking.

  That is, in the case of high frequency use in which the crystal piece 2 has a flat plate shape, the corners on both sides of the one end are substantially perpendicular, so that a bonding area for the crystal terminal 3 having a rectangular shape is secured, and no particular problem occurs. However, when the end face is processed for low frequency use, the corners on both sides of the one end are arcuate, and the bonding area to the crystal terminal 3 is reduced. Therefore, the fixing strength is reduced and the impact resistance is deteriorated.

  From this, for example, as shown in FIG. 6, it can be considered that the distance W1 between the pair of crystal terminals 3 is narrowed to increase the bonding area. However, in this case, the inclined surfaces in the width direction of the crystal piece 2 abut against the inner ridge lines of the crystal terminal 3. Therefore, the contact portion of the inclined surface of the crystal piece 2 is closer to the center, and the distance d1 from the crystal terminal 3 becomes larger at both ends in the width direction.

  On the other hand, the conductive adhesive 7 is applied to both ends in the width direction of the crystal piece 2 to reduce the influence on the vibration characteristics in the central region. Therefore, when the conductive adhesive 7 is applied on the crystal terminals 3 on both ends of the crystal piece 2 in the width direction, both sides of one end of the crystal piece 2 having the inclined surface are brought into contact and pressed. The conductive adhesive 7 is not pressed at both ends in the width direction of the crystal piece 2.

  For this reason, the thickness of the conductive adhesive 7 on both sides of one end of the crystal piece 2 is increased, and the conductive adhesive 7 does not spread and the bonding area (coating area) decreases. Accordingly, the fixing strength of the crystal piece 2 by the conductive adhesive 7 to the crystal terminal 3 is lowered. In this case, even if the amount of the conductive adhesive 7 is increased to widen the bonding area, the thickness at both ends is not reduced, and the fixing strength against impact is hardly improved.

  Further, if the amount of the conductive adhesive 7 is further increased, the conductive adhesive 7 adheres to the center of the crystal piece 2 as described above and deteriorates the vibration characteristics, so that it cannot be adopted. As a result, when the crystal piece 2 having an inclined surface is fixed to the crystal terminal 3 of the container body 1 common to various crystal pieces 2 by end face processing, there is a problem of deteriorating impact resistance.

  For this reason, for example, as shown in FIG. 7, it is conceivable to increase the length of the crystal terminal 3. However, in this case, since the crystal piece 2 has an inclined surface in the length direction, the distance m to the contact position with the crystal terminal 3 becomes long. Therefore, the distance d2 between the one end of the crystal piece 2 and the crystal terminal 3 is increased, and the thickness of the conductive adhesive 7 is increased as described above. Accordingly, also in this case, the fixing strength of the crystal piece 2 is lowered, and the impact resistance is deteriorated.

(Object of invention)
The present invention provides a crystal device for surface mounting that can share a container main body corresponding to crystal pieces having different widths, and in particular, has improved the adhesion strength of the crystal piece whose end face has been processed on the outer periphery to maintain good impact resistance. The purpose is to do.

  According to the present invention, as shown in the claims (Claim 1), a pair of one end portions of the crystal piece from which the extraction electrode extends from the excitation electrode are provided on both sides of the one end portion of the inner bottom surface of the mounting substrate. In the crystal device for surface mounting, which is fixed to the crystal terminal with a conductive adhesive, the pair of crystal terminals have an inclined portion in which the distance between the side surfaces facing each other gradually increases toward the central portion of the inner bottom surface. And the lead electrode of the said crystal piece extends, and it is set as the structure which fixed the one end part both sides which have an inclination part to a pair of said crystal terminal.

  If it is such a structure, a container main body can be shared similarly to the past, even if a crystal piece is flat plate shape or it is the curved surface shape which processed the end surface. For example, what is necessary is just to set the distance between the base parts where the space | interval of the mutually opposing side surface (inclined part) of a pair of crystal terminal becomes the narrowest as a target. In this case, a wider crystal piece can be fixed at a position where the interval in the direction opposite to the root portion is wider.

(Embodiment section)
According to a second aspect of the present invention, in the first aspect, the crystal piece is gradually narrowed in the length and width direction in the plan view, and the thickness of the crystal piece is gradually increased from the central portion toward the outer peripheral portion. And the thickness of the inclined portion of the crystal terminal at the corner portion of the outer peripheral portion is the same in the oblique direction.

  In this case, the inclined portions on the opposite side surfaces of the pair of crystal terminals abut on an area having the same thickness that obliquely intersects both corners of one end of the crystal piece. Therefore, even if the length of the crystal terminal on the inner bottom surface of the container body is increased, the distance from the area where the crystal piece abuts to the outer peripheral end of the crystal piece can be shortened. And the contact distance of the inclination part which expanded the length of the crystal terminal, and a crystal piece also becomes large.

  For these reasons, when the conductive adhesive is applied and pressed, the conductive adhesive spreads to increase the area and thickness. Therefore, the adhesion area to the crystal terminals on both sides of the one end portion of the crystal piece is increased, the fixing strength is increased, and the impact resistance is improved.

  In the third aspect of the present invention, in the second aspect, the thickness of the crystal piece has a contour line similar to the contour of the crystal piece, and the inclined portion of the crystal terminal is in the direction of the contour line. Thereby, the shape of the crystal piece is further clarified, and the configuration in claim 2 is made more concrete.

  FIG. 1 is a view for explaining an embodiment of the present invention. FIG. 1 (a) is a plan view excluding a cover of a surface-mounted vibrator, FIG. 1 (b) is a plan view of a crystal piece, and FIG. Is a partially enlarged view. 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. FIG. 1 (b) is the same as FIG. 4 (c).

  As described above, the surface-mounted vibrator is electrically connected to the crystal terminal 3 provided on the inner bottom surface of the container body 1 having the external terminal 4 on both sides of one end portion of the crystal piece 2 where the extraction electrode 6b extends from the excitation electrode 6a. It adheres with the adhesive 7 and covers the metal cover 5 and hermetically seals (see FIG. 4 above). The crystal piece 2 is end-face processed into a bevel or convex shape for low frequency use. Alternatively, a flat plate is used for high frequency. The figure shows a crystal piece that has been end-face processed.

  The end face processing of the crystal piece 2 is also formed using a cylinder or a sphere (not shown), and the outer peripheral portion in the length and width directions is gradually narrowed in plan view. And it has the inclination part from which the thickness of the crystal piece 2 becomes small gradually toward an outer peripheral part from a center part. In this case, the thickness of the crystal piece 2 is a contour line similar to the outline of the crystal piece 2 as described above. Therefore, the thickness of the inclined portion at the corner portion of the outer peripheral portion is set to the same thickness in the direction of obliquely intersecting the corner portion.

  In this embodiment, the pair of crystal terminals 3 on both sides of the one end portion provided on the inner bottom surface of the container body 1 sets the distance between the root portions on the inner wall side to the narrowest crystal piece 2 as in the conventional case. Is done. The side surfaces of the crystal terminals 3 that face each other are, for example, parallel at the roots and V-shaped inclined portions that gradually increase in distance toward the center of the inner bottom surface. The inclined part is in the same direction as the contour lines of the crystal pieces on both sides of one end of the crystal piece.

  In such a case, first, a heat-curing liquid conductive adhesive 7 is discharged onto a pair of crystal terminals 3 from a nozzle tip (not shown). In this case, the conductive adhesive 7 is applied on the crystal terminal 3 in a substantially circular shape. Next, both sides of one end portion of the crystal piece 2 are brought into contact with the pair of crystal terminals 3 (FIG. 2A). The other end portion of the crystal piece 3 comes into contact with a pillow portion 8 provided on the other end side of the inner bottom surface.

  Then, a jig or the like (not shown) is pressed from the upper surface on both sides of the one end portion of the crystal piece, and the conductive adhesive 7 is spread by the pressing force. In this case, the conductive adhesive 7 spreads along the arc-shaped outer periphery of the crystal piece 2 and becomes substantially elliptical (FIG. 2B). Thereby, the conductive adhesive 7 is applied over the outer periphery including the lower surface on both sides of one end of the crystal piece 2 and the end surface of the crystal piece. Finally, the conductive adhesive 7 is cured by heating, and both ends of one end of the crystal piece 2 are fixed on the crystal terminal 3.

  With such a configuration, the pair of crystal terminals 3 is set for the narrowest crystal piece 2, so that either the narrow crystal piece 2 or the wide crystal piece 2 is fixed as in the conventional case. The container body 1 can be shared. In this case, in the case of the crystal piece 2 having a wide width, it can be fixed at a portion having a wide interval among the inclined portions having a V shape.

  And in this embodiment, when it is end-face-processed and has a curved-shaped inclination part in an outer peripheral part, it becomes next. That is, the inclined portions of the side surfaces of the pair of crystal terminals 3 facing each other are in the direction of the contour lines on both sides of one end portion of the crystal piece 2. Therefore, the inclined portion of each crystal terminal 3 obliquely intersects each corner of the crystal piece 2 and comes into contact with the region of the crystal piece 2 having the same thickness on almost the contour line to form a line contact.

  On the other hand, in the case of the conventional quartz terminal 3 having a rectangular shape without an inclined portion, the opposing corners on the center side of the inner bottom surface of the container body 1 are in contact with the inclined surface of the crystal piece 2. Point contact. Therefore, conventionally, the distance from both corners that are point contacts to the outer peripheral end of the crystal piece is increased, and the distance between the crystal terminal and the outer peripheral end is increased.

  In this respect, in the present embodiment, as described above, the inclined portion of each crystal terminal 3 obliquely crosses each corner portion of the crystal piece 2 and comes into contact with a region on the contour line having the same thickness to form a line contact. Therefore, the distance from the region that is in line contact to the outer peripheral end of the crystal piece is shortened, and the distance d2 (not shown) between the outer peripheral end of the crystal piece 2 and the crystal terminal 3 is made smaller than d1 of the conventional example. Accordingly, the conductive adhesive 7 applied on the crystal terminal 3 is pressed to be spread in an elliptical shape along the direction of the inclined portion. From this, the contact area with respect to the crystal terminals 3 on both sides of the one end portion of the crystal piece 2 can be increased to increase the fixing strength and improve the impact resistance.

  In the conventional example, since the corner of the crystal terminal 3 is in point contact with the inclined surface of the crystal piece, for example, when the conductive adhesive 7 is increased and pressed, the conductive adhesive 7 is the crystal terminal. 3 tends to flow out from the inner periphery of the crystal 3 and adheres to the main surface of the crystal piece 2 to deteriorate the vibration characteristics. On the other hand, in this embodiment, since the inclined portion of the crystal terminal 3 abuts on the inclined surface to make a line contact, the outflow of the conductive adhesive 7 from the inner periphery of the crystal terminal 3 is prevented and vibration characteristics are improved. Keep good.

(Other matters)
In the above embodiment, the inclined portion of the crystal terminal 3 is linear, but it is needless to say that it may be curved along contour lines. Further, although the surface-mount crystal device has been described as a surface-mount resonator, the present invention is not limited to this. For example, even when an IC chip and a crystal piece 2 are accommodated in the same container to form a surface-mount oscillator (not shown). The present invention can be similarly applied as long as both sides of one end of the crystal piece 2 are held.

1A and 1B are diagrams illustrating an embodiment of the present invention, in which FIG. 1A is a plan view excluding a cover of a surface mount vibrator, FIG. 1B is a plan view of a crystal piece, and FIG. FIG. It is a partially enlarged mounting plan view of a crystal piece for explaining the operation of one embodiment of the present invention. It is a mounting top view of a partial enlargement of the crystal piece of the prior art example compared with one embodiment of the present invention. FIG. 4A is a cross-sectional view of a surface-mounted vibrator, FIG. 2B is a plan view excluding a cover, and FIG. 2C is a plan view of a crystal piece. It is a top view of the crystal piece explaining a prior art example. It is mounting sectional drawing of the partially expanded crystal piece explaining a prior art example. FIG. 5A is a plan view of a surface-mounted vibrator excluding a cover, and FIG. 5B is a partially enlarged mounting cross-sectional view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 Crystal piece, 3 Crystal terminal, 4 External terminal, 5 Metal cover, 6 Excitation and extraction electrode, 7 Conductive adhesive agent, 8 Pillow part.

Claims (3)

One end sides of the crystal element where the lead electrodes from the excitation electrode extends, quartz for surface mounting comprising fixed by a conductive adhesive to a pair of crystal terminals provided on one end sides of the inner bottom surface of the mounting substrate in the device, the distance between the sides facing each other of the pair of crystal terminals has a larger inclined part gradually toward the center of the inner bottom surface, the inclined portion out the extraction electrode extension of the crystal piece quartz crystal device for surface mounting to the one end sides, characterized in that it is fixed to the pair of crystal terminals having. In claim 1, the outer peripheral portion of the length and width directions of the crystal piece, together with the narrower gradually in a plan view, reduced slope gradually towards the outer peripheral portion thickness of the crystal blank from the central portion A crystal device for surface mounting in which the thickness of the inclined portion at the corner portion of the outer peripheral portion is the same thickness in a direction obliquely intersecting the corner portion. In claim 2, the thickness of the crystal piece has a contour which is similar to the contour of the crystal piece, a quartz crystal device for the surface mounting is formed in the direction of the inclined portion and the contour of the crystal terminals.