JP2010154158A - Surface mount crystal oscillator - Google Patents

Abstract

Disclosed is a surface-mount crystal oscillator with a small yield and a high yield even when it is downsized.
A container body 1 in which a lower frame wall 1b and an upper frame wall 1c are stacked on a bottom wall 1a, a crystal piece whose outer peripheral portion is fixed to an inner wall step of the container body 1, and an inner bottom surface of the container body 1 A crystal inspection terminal 11 that is provided with a fixed IC chip and a metal cover 5, has a first conductive path 12 a formed on the upper surface of the bottom wall 1 a, and is formed in a depression on the outer surface of the lower frame wall 1 b. The second conductive path 12b is formed on the lower surface of the lower frame wall 1b along the outer periphery of the recess to be connected, and the first conductive path 12a and the second conductive path 12b are the bottom wall 1a and the lower frame wall 1b. In the surface-mount crystal oscillator having the overlapping portion 13 that is electrically connected at the interface, a metal film 17 that is a reinforcing film is provided on the interface between the bottom wall 1a and the lower frame wall 1b. 17 and the superposition part 13 are arranged symmetrically with respect to the center line BB that bisects the side that becomes the interface. To.
[Selection] Figure 1

Description

  The present invention has a surface mount crystal oscillator (hereinafter referred to as a surface mount oscillator) as a technical field, and particularly prevents the adverse effect caused by the overlapping portion of the conductive path formed at the interface between the lower frame wall and the bottom wall of the container body. The present invention relates to a surface mount oscillator.

(Background of the Invention)
Since the surface-mounted oscillator is small and light, it is widely used as a frequency and time reference source, particularly in portable electronic devices typified by cellular phones. In recent years, with the miniaturization of electronic devices, the demand for miniaturization of surface mount oscillators has been further increased. One of such devices is a surface mount oscillator in which a crystal piece and an IC chip are accommodated in a container body and hermetically sealed with a metal cover.

(Example of conventional technology)
3 and 4 are views of a surface-mount oscillator for explaining a conventional example. FIG. 3 is a perspective view, FIG. 4 (a) is a cross-sectional view, and FIG. 3 (b) is a lower frame wall and a bottom wall. FIG. 4C is an interface view between the lower frame wall and the bottom wall, and FIG. 4D is a perspective view of the crystal piece.

  A surface-mount oscillator disclosed as a conventional technique in Patent Document 1 contains an IC chip 2 and a crystal piece 3 in a container body 1, and a metal ring 4 provided on the upper surface of a frame wall serving as an opening end surface of the container body 1. The cover 5 is joined. The container body 1 includes a bottom wall 1a, a lower frame wall 1b, and an upper frame wall 1c. The container body 1 is formed by firing a ceramic having a concave portion and a stepped portion and having a multilayer structure.

  The IC chip 2 integrates each element such as an amplifier constituting an oscillation circuit, and has IC terminals (not shown) on one main surface as a circuit function surface. Then, one main surface side of the IC chip 2 is fixed to the bottom surface of the concave portion of the container body 1 by, for example, ultrasonic thermocompression using bumps 6 (so-called flip chip bonding). Each IC terminal (for example, power supply, ground, output, AFC terminal) (not shown) of the IC chip 2 is electrically connected to mounting terminals 7 formed at the four corners of the outer bottom surface of the container body 1.

  The quartz crystal piece 3 has, for example, extraction electrodes 8b extending from the excitation electrodes 8a on both main surfaces to both sides of one end. Then, both sides of one end of the extraction electrode 8b are fixed to the crystal holding terminal 10 formed on the inner wall step of the container body 1 by the conductive adhesive 9. The crystal holding terminal 10 is electrically connected to a crystal terminal (not shown) of the IC chip 2.

  A first conductive path 12a is formed on the upper surface of the bottom wall 1a. Moreover, the container main body 1 has the crystal | crystallization inspection terminal 11 which is a communication terminal in the hollow of the outer surface of the lower frame wall 1b. A second conductive path 12b is formed on the lower surface of the lower frame wall 1b along the outer periphery of the recess electrically connected to the crystal inspection terminal 11. The first conductive path 12a and the second conductive path 12b are electrically connected by the overlapping portion 13. The crystal inspection terminal 11 is electrically connected to the crystal piece 3 via the second conductive path 12b and the first conductive path 12a, the electrode through hole 14 formed in the lower frame wall 1b, and the crystal holding terminal 10. . Although it is possible to provide the first conductive path 12a on the lower surface of the lower frame wall 1b, the first conductive path 12a is formed on the bottom wall 1a as shown in FIG. There is a case where it is necessary to provide it on the upper surface.

  The metal cover 5 is made of Kovar in which Ni (nickel) and Co (cobalt) are added with Fe (iron) as a main component. On the surface of the cover base, for example, a Ni film (not shown) by electrolytic plating is provided. The metal cover 5 is joined to the metal ring 4 provided on the opening end surface of the container body 1. The metal cover 5 is electrically connected to the ground terminal in the mounting terminal 7 through a via hole or the like. Surface mount oscillators based on these are surface-mounted by, for example, solder in a high temperature furnace transported to a set substrate of a portable device.

  In such a case, after the IC chip 2 and the crystal piece 3 are accommodated in the container main body 1 provided on the upper surface of the frame wall where the metal ring 4 serves as the opening end face, the metal cover 5 is disposed on the metal ring 4. Then, as shown in FIG. 5, a pair of electrode rollers 15 are brought into contact with a pair of opposing sides of the metal cover 5 and rotated while being energized (see Patent Document 2).

Thereby, the Ni film is melted by Joule heat due to the contact resistance between the metal cover 5 and the metal ring 4, and the metal cover 5 is joined to the metal ring 4 (so-called seam welding). Next, the other sets of opposite sides are joined in the same manner. Normally, the metal cover 5 is temporarily fixed to the metal ring 4 by a seam welder or a spot welder, and then seam welded.
Japanese Patent Laid-Open No. 2008-067265 (refer to “Example of Prior Art”) Japanese Patent Laying-Open No. 2006-102771 (see “Example of Prior Art”)

(Problems of conventional technology)
However, in the surface mount oscillator having the above configuration, depending on the thickness of the overlapping portion 13, as shown in FIG. 6, the bottom surface of the overlapping portion 13 is laminated and fired on the bottom wall 1a, the lower frame wall 1b, and the upper frame wall 1c. The bottom surface of the container body 1 may be distorted in a convex shape toward the bottom surface of the container body 1. When seam welding is performed using the container body 1 having a distorted bottom surface, when the electrode roller 15 advances at both ends of the portion where the convex distortion is formed, the stress due to the pressing of the electrode roller 15 is reduced. There is a problem that cracks 16 are concentrated in the lower part of the overlapping portion 13. Such distortion of the container main body 1 becomes more noticeable as the planar outer shape of the container main body 1 becomes smaller, and the probability that the crack 16 is generated increases.

(Object of invention)
It is an object of the present invention to provide a surface mount oscillator with a high yield by reducing the distortion of the container body even when it is downsized.

  The present invention provides a concave container body having an inner wall step portion in which a lower frame wall and an upper frame wall are laminated on a bottom wall, and an inner wall step portion of the container body, as shown in claims (Claim 1). A crystal piece to which the outer peripheral portion of the extraction electrode extending from the excitation electrode is fixed, an IC chip that forms an oscillation circuit together with the crystal piece and is fixed to the inner bottom surface of the container body, and an opening end surface of the container body A cover that seals and encloses the crystal piece and the IC chip, has a first conductive path formed on the top surface of the bottom wall, and communication formed in a recess on the outer surface of the lower frame wall A second conductive path formed on a lower surface of the lower frame wall along an outer periphery of the depression electrically connected to the terminal, wherein the first conductive path and the second conductive path are the bottom wall and the Crystal mounting for surface mounting with overlapping parts that are electrically connected at the interface of the lower frame wall A reinforcing film is provided at an interface between the bottom wall and the lower frame wall, and the reinforcing film and the overlapping portion are arranged symmetrically with respect to a center line that bisects the side serving as the interface And

  With such a configuration, the reinforcing film and the overlapping portion are formed at positions that are symmetric with respect to the center line, so that the convex distortion generated on the bottom surface of the container body is moderated. Therefore, even if a pair of opposite sides of the cover is pressed by the electrode roller during seam welding, the stress will be distributed without concentrating on one place, and the probability that cracks will occur in the container body will be reduced and the yield will be reduced. High surface mount oscillators can be provided.

(Embodiment section)
According to claim 2 of the present invention, in claim 1, the overlapping portion is formed in one region divided by a center line that bisects the side that becomes the interface, and the reinforcing film is formed in another region. The configuration. Thereby, the arrangement of a specific example of the overlapping portion and the reinforcing film is clarified.

  According to a third aspect of the present invention, in the first aspect, the overlapping portion is formed on a center line that bisects the side serving as the interface, and the reinforcing film is formed in one region and another region separated by the center line. Is formed. Thereby, the arrangement of specific other examples of the overlapping portion and the reinforcing film is clarified.

  According to a fourth aspect of the present invention, in the first to third aspects, the reinforcing film is a metal film. As a result, a metal film serving as a reinforcing film can be provided simultaneously with the formation of the first conductive path, so that a step of providing a separate reinforcing film is unnecessary, and the container body can be easily formed.

(Equivalent to the first embodiment, claims 1, 2, and 4)
FIG. 1 is a diagram of a surface mount oscillator for explaining a first embodiment of the present invention. FIG. 1 (a) is an exploded view of a lower frame wall and a bottom wall, and FIG. 1 (b) is a lower frame wall and a bottom. The interface with the wall, FIG. 10C is a cross-sectional view taken along the line AA of FIG. 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 crystal oscillator for surface mounting shown in FIG. 1 has an IC chip 2 and a crystal piece 3 placed on a concave container body 1 having an inner wall stepped portion by laminating a lower frame wall 1b and an upper frame wall 1c on a bottom wall 1a. A metal cover 5 is joined to a metal ring 4 which is accommodated and provided on the opening end surface of the container body 1. The container main body 1 has a rectangular planar outer shape, and uses ceramic as a base material. A crystal inspection terminal 11 serving as a communication terminal is formed on the outer surface of the lower frame wall 1b.

  And the 1st conductive path 12a and the 2nd conductive path 12b are provided similarly to a prior art example. The overlapping portion 13 of the first conductive path 12a and the second conductive path 12b is provided in a region divided by a center line BB that bisects the side that becomes the interface between the bottom wall 1a and the lower frame wall 1b. . And here, the metal film 17 which is a reinforcement film | membrane is formed in the position symmetrical with the superimposition part 13 with respect to centerline BB. The thickness of the metal film 17 is approximately the same as that of the overlapping portion 13 (see FIG. 4A).

  In such a case, first, the first conductive path 12a and the metal film 17 are formed on the upper surface of the bottom wall 1a by printing tungsten. At this time, the thickness of the metal film 17 is made equal to the thickness of the overlapping portion 13. By forming a through hole in the lower frame wall 1b and printing tungsten, the base electrode of the crystal inspection terminal 11 and the electrode through hole 14 are formed. Further, a second conductive path 12b is formed on the lower surface of the lower frame wall 1b by printing tungsten.

  Thereafter, the bottom wall 1a, the lower frame wall 1b, and the upper frame wall 1c are laminated and fired to form the container body 1. By this lamination, an overlapping portion 13 of the first conductive path 12a and the second conductive path 12b is formed. Then, for example, an Au film is formed on the surface of the base electrode by electrolytic plating or electroless plating to form the crystal inspection terminal 11. Thereafter, the IC chip 2 and the crystal piece 3 are accommodated in the container body 1, and the metal cover 5 is joined to the metal ring 4 provided on the upper surface of the frame wall serving as the opening end surface of the container body 1 by seam welding.

  With such a configuration, the metal film 17 is formed at a position symmetric to the overlapping portion 13 with respect to the center line BB, so that the convex distortion generated on the bottom surface of the container main body 1 is moderated. Therefore, even if a pair of opposing sides of the metal cover 5 are pressed by the electrode roller 15 during seam welding, the stress is dispersed without concentrating on one place, so that the probability of the crack 16 occurring in the container body 1 is reduced. Thus, it is possible to provide a surface mount oscillator with a high yield. Furthermore, since the reinforcing film is the metal film 17, the conductive path 12a and the metal film 17 can be formed simultaneously by printing, compared to, for example, a case where the reinforcing film is a ceramic coat.

(Embodiment 2 corresponds to claims 1, 3, and 4)
FIG. 2 is a diagram of a surface mount oscillator for explaining a second embodiment of the present invention. FIG. 2 (a) is an exploded view of the lower frame wall and the bottom wall, and FIG. 2 (b) is the lower frame wall and the bottom. It is an interface figure with a wall. In addition, the same number is given to the same part as previous embodiment, and the description is simplified or abbreviate | omitted.

  In the second embodiment, the overlapping portion 13 of the first conductive path 12a and the second conductive path 12b is formed on the center line BB. Further, the metal film 17 is formed symmetrically with respect to the center line BB in one region and the other region divided by the center line BB on the upper surface of the bottom wall 1a. With such a configuration, for the convenience of wiring, even when the overlapping portion 13 is formed on the center line BB, the overlapping portion 13 and the metal film 17 are disposed symmetrically with respect to the center line BB. Therefore, the distortion of the container body 1 can be moderated and the same effect as that of the first embodiment can be obtained.

(Other matters)
In each of the above embodiments, the IC chip 2 in which the temperature compensation mechanism is integrated may be used. In this case, not the crystal inspection terminal 11 but a writing terminal for inputting temperature compensation data to the temperature compensation mechanism is formed on the outer surface of the lower frame wall 1b. The writing terminal is electrically connected to the IC chip 2 via the second conductive path 12b and the first conductive path 12a electrically connected by the overlapping portion 13. In each of the above embodiments, it is needless to say that the metal film 17 and the overlapping portion 13 do not need to be arranged with complete symmetry with respect to the center line BB. The reinforcing film is the metal film 17, but may be a ceramic coat. However, as described above, the metal film 17 is better from the viewpoint of workability.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the surface mount oscillator explaining 1st Embodiment of this invention, The figure (a) is an exploded view of a lower frame wall and a bottom wall, The figure (b) is an interface of a lower frame wall and a bottom wall. The figure and the figure (c) are AA sectional views of the figure (b). FIG. 5A is an exploded view of a lower frame wall and a bottom wall, and FIG. 5B is an interface between the lower frame wall and the bottom wall, illustrating a surface-mounted oscillator for explaining a second embodiment of the present invention. FIG. It is a perspective view of the surface mount oscillator explaining a conventional example. FIG. 1A is a cross-sectional view of a surface mount oscillator for explaining a conventional example, FIG. 2B is an exploded view of a lower frame wall and a bottom wall, and FIG. The interface with the bottom wall, FIG. 4D is a perspective view of the crystal piece. It is a perspective view showing the time of the seam welding of the surface mount oscillator explaining a prior art example. It is AA sectional drawing of FIG.4 (c) showing the time of the seam welding of the surface mount oscillator explaining a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 IC chip, 3 Crystal piece, 4 Metal ring, 5 Metal cover, 6 Bump, 7 Mounting terminal, 8a Excitation electrode, 8b Extraction electrode, 9 Conductive adhesive, 10 Crystal holding terminal, 11 Crystal inspection terminal , 12a 1st conductive path, 12b 2nd conductive path, 13 overlapping part, 14 electrode through-hole, 15 electrode roller, 16 crack, 17 metal film.

Claims (4)

A concave container body having an inner wall step formed by laminating a lower frame wall and an upper frame wall on a bottom wall; and a crystal piece to which an outer peripheral portion of an extraction electrode extending from an excitation electrode is fixed to the inner wall step of the container body An IC chip that forms an oscillation circuit together with the crystal piece and is fixed to the inner bottom surface of the container body, and a cover that seals and seals the crystal piece and the IC chip bonded to the opening end surface of the container body,
The lower frame wall has a first conductive path formed on the upper surface of the bottom wall and is connected to a communication terminal formed in a recess on the outer surface of the lower frame wall along the outer periphery of the recess. A second conductive path formed on the lower surface;
In the crystal oscillator for surface mounting, wherein the first conductive path and the second conductive path have an overlapping portion that is electrically connected at an interface between the bottom wall and the lower frame wall,
A reinforcing film is provided at an interface between the bottom wall and the lower frame wall, and the reinforcing film and the overlapping portion are arranged symmetrically with respect to a center line that bisects the side serving as the interface. Surface mount crystal oscillator.   2. The surface-mount crystal oscillator according to claim 1, wherein the overlapping portion is formed in one region divided by a center line that bisects the side serving as the interface, and the reinforcing film is formed in another region.   2. The surface-mounting device according to claim 1, wherein the overlapping portion is formed on a center line that bisects the side serving as the interface, and the reinforcing film is formed in one region and the other region divided by the center line. Crystal oscillator. 4. The surface-mount crystal oscillator according to claim 1, wherein the reinforcing film is a metal film.