JP2009105779A - Crystal device for surface mounting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crystal device for surface mounting which maintain good impact resistance. <P>SOLUTION: In the crystal device, both sides at one end of a crystal chip 2 in which a lead-out electrode extends from an excitation electrode are fixed to a crystal terminal 3 provided on both sides at one end on an inner bottom surface of a mounting substrate using a conductive adhesive 7. The crystal terminal 3 provided on both sides at one end includes an area with the small thickness closer to the center and an area with the large thickness closer to the outside, while both facing each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

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)
3A and 3B are diagrams for explaining a conventional example. FIG. 3A is a cross-sectional view of a surface-mounted vibrator, FIG. 3B is a plan view excluding a cover, and FIG. 3C 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 approximately 30 MHz or more, the crystal piece 2 is shaped like a flat plate, and in the lower frequency band below that, the 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 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.

  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. 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, for example, W (tungsten) or Mo (molybdenum) is printed as a double coating as shown in FIG. Increase (thickness). These are integrally fired together with the container body 1 and then plated with Ni (nickel) and Au (gold). Since the crystal terminal 3 is formed by printing, the area becomes smaller as it becomes an upper layer by the width of the plating frame. Further, since the first layer 3a (lowest layer) is, for example, a circuit pattern connected to the external terminal 4, the thickness of the first layer 3a is the smallest and the second layer 3b is thickened.

  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. The dimension in the width direction varies depending on the vibration frequency band, and the spurious vibration caused by the dimension in the width direction is avoided. 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-described configuration, although the container body 1 is shared in correspondence with the crystal pieces 2 having different width directions, the fixing strength of the crystal piece 2 that is particularly end-face processed (bevel or convex) is small. There was a problem of lack of so-called impact resistance properties that peeled off against impact.

  That is, at the time of fixing (mounting) the crystal piece 2 having a large width in the end face processing, the inclined surface in the width direction of the crystal piece 2 having the end face processed is the crystal terminal 3 as shown in FIG. They abut against the inner corners (ridges). In this case, since the crystal terminal 3 also fixes the crystal piece 2 having a small width, the distance W1 between the crystal terminals 3 is short. 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, when 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 to deteriorate the vibration characteristics, or the spread of the conductive adhesive 7 varies. The vibration characteristics are non-uniform and 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.

(Object of invention)
It is an object of the present invention to provide a surface-mount crystal device that maintains good impact resistance characteristics.

  According to the present invention, as shown in the claims (Claim 1), both ends of one end portion of the crystal piece in which the extraction electrode extends from the excitation electrode are disposed on both sides of the one end portion of the inner bottom surface of the mounting substrate. In a surface-mount crystal device that is fixed to a terminal with a conductive adhesive, the crystal terminals provided on both sides of the one end are composed of a region with a small thickness near the center and a region with a large thickness near the outside. Constitute.

  With this configuration, the lead electrode is extended to a crystal terminal with a small thickness near the center when the width of the crystal piece is small, and to a crystal terminal with a large thickness near the outside when the width of the crystal piece is large. The one end of both ends can be fixed. Therefore, as in the prior art, various crystal pieces with different widths can be mounted to increase productivity.

And if the width dimension is large and there is an inclined surface by end face processing, the central area of the thick crystal piece is buried in a recess with a small thickness, and the inclined surface is on the inner ridge line part with a large thickness. Abut. Therefore, the distance from the crystal terminals on both ends in the width direction of the crystal piece is shortened as compared with the conventional example. As a result, the conductive adhesive on the crystal terminals located at both ends of the crystal piece is pressed to reduce the thickness and increase the coating area, so that the fixing strength can be increased and the impact resistance can be maintained well.

(Embodiment section)
According to a second aspect of the present invention, in the first aspect, the region having the large thickness and the region having the small thickness are flat. Thereby, even when the width of the crystal piece is large or small, the both ends of the crystal piece from which the extraction electrode extends and the crystal terminal can be adhered and fixed by the conductive adhesive.

  In claim 3, the crystal terminal according to claim 1 is composed of a first layer, a second layer, and a third layer formed in order from the inner bottom surface of the container body, and the first layer is a circuit pattern serving as a wiring path. A step is provided between the second layer and the third layer so that the second layer is a region having a small thickness and the third layer is a region having a large thickness. Thereby, the area | region with a small thickness and the area | region with a large thickness in Claim 1 can be formed.

  In claim 4, the crystal terminal according to claim 1 is composed of a first layer and a second layer formed on the inner bottom surface of the container body, the first layer being a circuit pattern serving as a wiring path, and the second layer Is formed over the inner bottom surface of the mounting substrate from above the first layer, and the second layer formed on the inner bottom surface is the region having the small thickness, and the first layer and the second layer on the first layer Is a region having a large thickness. Thereby, the area | region with a small thickness in Claim 1 and the area | region with a large thickness can be formed similarly to Claim 2. And in this case, since it can form as a two-layer structure, when forming each layer, for example by printing, a manufacturing process can be reduced rather than the case of Claim 2.

  FIG. 1 is a partially enlarged cross-sectional view of a surface-mounted vibrator for explaining an embodiment of the present invention. 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.

  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. 3 above). The crystal piece 2 is end-face processed into a bevel or convex shape for low frequency use, and has an inclined surface in the length and width directions. Alternatively, a flat plate is used for high frequency.

  In this embodiment, the crystal terminals 3 provided on both sides of one end of the inner bottom surface of the container body 1 are composed of a region having a small thickness and a region having a large thickness. Here, for example, the first layer 3a, the second layer 3b, and the third layer 3c are sequentially formed from the inner bottom surface of the container body 1, and each layer is formed as a flat three-layer structure. These are all formed by printing W or Mo as described above, the first layer 3a is a circuit pattern connected to the external terminal 4, and the second layer 3b is printed on the first layer 3a as in the prior art.

  Here, the third layer 3c is formed with a step in a substantially half region extending from the center of the second layer 3b to the outer peripheral side. As a result, the interval W2 on the inner peripheral end side of the third layer 3c (uppermost layer) becomes larger than the conventional interval W1. Then, the surface of the second layer 3b and the third layer 3c in the crystal terminal 3 is used as a mounting region for the crystal piece 2 having a small width and the crystal piece 2 having a large width. The thickness of each layer of the crystal terminal 3 is, for example, 10 μm.

  If it is such a structure, the one end part both sides of the flat-shaped crystal piece 2 with a small width | variety will adhere to the 2nd layer 3b with the conductive adhesive 7, for example. Further, both ends of one end of the crystal piece 2 having an inclined surface are fixed to the third layer 3c by end face processing having a large width. Therefore, the container main body 1 can be shared corresponding to the crystal pieces 2 having different widths as in the prior art.

  Further, here, a step is provided between the second layer 3b and the third layer 3c to increase the interval W2 between the inner peripheral ends of the third layer 3c. In other words, the interval between the inner peripheral end and the outer peripheral end of the third layer 3c is shortened. Therefore, when the crystal piece 2 having an inclined surface is mounted by end face processing, the thick central region is buried in a recess in the step between the second layer 3b and the third layer 3c. And the inclined surface near the outer periphery of the crystal piece 2 is in contact with the ridge line portion at the inner peripheral end of the third layer 3c.

  Therefore, the distance from the contact point with respect to the ridge line portion of the crystal piece 2 to the outer peripheral end becomes shorter, and the separation distance d2 with respect to the third layer 3c at the outer peripheral end becomes smaller than the conventional one. Even in these cases, as in the prior art, a prescribed amount of conductive adhesive 7 is applied to the prescribed positions on the third layer 3c on both ends where the lead electrodes 6b in the width direction of the quartz piece 2 are formed. The one end portion side of the piece 2 is contacted and pressed.

  In this case, since the separation distance d2 with respect to the third layer 3c of the crystal piece 2 is short, the conductive adhesive 7 is pressed to reduce the thickness and have a spread. Therefore, the bonding area of the conductive adhesive 7 is also increased, and the fixing strength on both sides of one end of the crystal piece 2 to the crystal terminal 3 can be increased.

(Other matters)
In the above-described embodiment, the crystal terminal 3 has a three-layer structure of the first layer 3a, the second layer 3b, and the third layer 3c, and has a region having a small thickness and a region having a large thickness. For example, as shown in FIG. It may be a two-layer structure. That is, after the first layer 3a as a circuit pattern is formed by printing, the second layer 3b is formed over the inner bottom surface of the container body 1 from the first layer 3a.

As a result, the second layer 3b on the inner bottom surface is made a region having a small thickness, and the first layer 3a and the first layer 3b.
Let the second layer 3b on a be a region having a large thickness. Even in this case, the space between the inner peripheral ends of the thickest uppermost layer is set to W2 wider than the conventional one. Thereby, the same effect as the embodiment is obtained. And since the crystal terminal 3 is made into two layers, a manufacturing process can be made advantageous.

In addition, although the surface mount crystal device has been described as a surface mount resonator, it is not limited to this,
For example, even when the IC chip and the crystal piece 2 are accommodated in the same container to form a surface mount oscillator (not shown), the same applies as long as both ends of the crystal piece 2 are held.

It is a partial expanded sectional view of the surface mount vibrator explaining one embodiment of the present invention. FIG. 6 is a partially enlarged cross-sectional view of a surface-mounted vibrator for explaining another example of the present invention. FIG. 3A is a cross-sectional view of a surface-mounted vibrator, FIG. 2B is a plan view excluding a cover 5, and FIG. 1C is a plan view of a crystal piece 2. FIG. . It is a partial expanded sectional view of the surface mount vibrator explaining the problem of one conventional example.

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 (4)

  In the crystal device for surface mounting, in which both ends of one end of the crystal piece from which the extraction electrode extends from the excitation electrode are fixed to the crystal terminals provided on both ends of the inner bottom surface of the mounting substrate by a conductive adhesive, A crystal device for surface mounting, wherein the crystal terminals provided on both sides of the one end portion are composed of a region with a small thickness near the center and a region with a large thickness near the outside.   2. The surface mount crystal device according to claim 1, wherein the thick region and the thin region have a flat surface.   2. The crystal terminal according to claim 1, wherein the crystal terminal includes a first layer, a second layer, and a third layer formed in order from the inner bottom surface of the container body, and the first layer is a circuit pattern serving as a wiring path, A crystal device for surface mounting in which a step is provided between the third layer, the second layer is a region having a small thickness, and the third layer is a region having a large thickness.   In Claim 1, the said crystal terminal consists of the 1st layer and 2nd layer formed in the inner bottom face of the said container main body, The said 1st layer is set as the circuit pattern used as a wiring path, The said 2nd layer is from the said 1st layer above. The second layer formed over the inner bottom surface of the mounting substrate and formed on the inner bottom surface is set as the region with the small thickness, and the first layer and the second layer on the first layer are the region with the large thickness. Crystal device for surface mounting.