JP2009065471A - Crystal oscillator for surface mounting - Google Patents

Abstract

A surface-mount oscillator that reliably recognizes the directionality from the metal cover side and reliably grounds the metal cover to a ground potential.
An IC chip 2 and a crystal piece 3 are accommodated in a container body 1 made of a multilayer ceramic, and an external terminal 5 electrically connected to the IC chip 2 is provided on the outer bottom surface of the container body 1. The container body 1 has a metal film 6 electrically connected to the ground terminal in the external terminal 5 on the opening end face of the container body 1, and the metal cover 4 is bonded to the metal film 6 so that at least the crystal piece 3 is attached. In a surface-mounted crystal oscillator that is hermetically sealed and has a rectangular shape as viewed from the metal cover 4 and is point-symmetric with respect to the center, the outer surface of the container body 1 is formed across the height direction. The depression 10 has a conductive film 11 electrically connected to the metal film 6 and the ground terminal.
[Selection] Figure 1

Description

  The present invention relates to a surface mount crystal oscillator (hereinafter, referred to as a surface mount oscillator), and more particularly to a surface mount oscillator that ensures measurement of oscillation characteristics and grounding of a metal cover.

(Background of the Invention)
Since the surface-mounted oscillator is small and light, it is built in a portable electronic device typified by a cellular phone as a frequency or time reference source. In recent years, there is an increasing demand for eradication of defects in the production process and a reliable response to EMI (electromagnetic interference).

(Example of conventional technology)
FIG. 4 is a diagram of a surface-mount oscillator for explaining a conventional example, in which FIG. 4 (a) is a partially broken sectional view, FIG. 4 (b) is a plan view excluding a metal cover and a metal ring, FIG. ) Is a bottom view.

  The surface-mount oscillator is formed by housing an IC chip 2 and a crystal piece 3 in a container body 1 and covering a metal cover 4 in a hermetically sealed manner. The container body 1 is made of a laminated ceramic and has a concave shape with an inner wall step. On the outer bottom surface of the container body 1, there are external terminals 5 for surface mounting, such as power supply, output, ground and AFC terminals, and a metal film 6 is provided on the opening end surface. The metal film 6 is electrically connected to the ground terminal in the external terminal 5 through the electrode through hole 7 provided at the corner of the frame wall.

  The IC chip 2 integrates at least each element constituting the oscillation circuit (excluding the crystal resonator). When a stable temperature is obtained by compensating the frequency-temperature characteristics due to the crystal resonator, a temperature compensation mechanism is also integrated. The circuit function surface, which is one main surface of the IC chip 2, has an IC terminal (not shown) including a crystal terminal and the like, and ultrasonic thermocompression bonding using a bump 12 on the circuit terminal provided on the inner bottom surface of the container body 1. By flip chip bonding.

  The power supply, output, ground, and AFC terminal, excluding the crystal terminal in the IC terminal, are electrically connected to the corresponding external terminals 5 through the laminated surface. In the case of the temperature compensation type, a write terminal 8 a for writing temperature compensation data is provided on the outer surface of the container body 1. In this example, two dedicated write terminals 8a are provided on opposite outer surfaces in the long side direction.

  The crystal piece 3 has excitation electrodes (not shown) on both main surfaces, and extends extraction electrodes on both sides of one end. The extraction electrodes are formed by folding back on the opposite surfaces. Then, both ends of the extended end portion of the extraction electrode are fixed to a crystal terminal (not shown) of the inner wall step portion by, for example, the conductive adhesive 9. The crystal terminal is electrically connected to the IC terminal of the IC chip 2 through a conductive path (not shown). Here, the crystal terminal of the inner wall step portion also extends as the crystal inspection terminal 8b on the outer surface facing in the short side direction.

  The write terminal 8a and the crystal inspection terminal 8b are formed except for the uppermost layer and the lowermost layer of the multilayer ceramic in order to prevent an electrical short circuit. Then, depressions are formed in layers other than the uppermost layer. These are formed by so-called through-hole processing in which W (tungsten) is poured into a through-hole and fired in the form of a sheet-like ceramic, and are formed by being divided into individual container bodies 1.

The metal cover 4 is joined by seam welding or the like to a metal ring (not shown) joined to the metal film 6 on the opening end face of the container body 1 by silver brazing or the like. Then, after the crystal piece 3 is hermetically sealed, the vibration characteristics of the crystal resonator (crystal piece 3) are inspected by the crystal inspection terminal 8b, and temperature compensation data is written from the write terminal 8a, so that a temperature compensation type surface mount oscillator is obtained. To complete. Thereafter, the defective product is excluded and the product is displayed on the metal cover 4 including only the good product including the origin indication.
JP 2007-104032 A

(Problems of conventional technology)
However, in the surface mount oscillator configured as described above, the top and bottom and the left and right sides are symmetrical as viewed from the metal cover 4 side until the surface display oscillator is completed and the product display including the frequency is displayed on the surface of the metal cover 4 (fifth). Figure). Therefore, when the surface mount oscillator covered with the metal cover 4 is accommodated in the jig and the oscillation characteristics are inspected, the surface mount oscillator is accommodated in the jig with the length direction reversed. There was a difficult problem in confirming correctness.

  In this case, the arrangement of the external terminals 5 on the outer bottom surface is determined, and for example, the power source and the ground terminal are set diagonally. Therefore, when the surface-mounted oscillator is housed in the reverse direction, a reverse voltage is applied between the power supply and the ground terminal, and an excessive current is generated in the IC chip 2 to cause deterioration of characteristics or damage. Normally, the external terminal 5x having a different shape from the other external terminals 5 is image-recognized and accommodated in a jig. However, it may be accommodated in the reverse direction due to an image recognition failure or the like.

  Further, as the surface-mount oscillator is further miniaturized, the frame width becomes narrower and it becomes difficult to form a via hole made of conductive paste such as W (tungsten) in the frame wall. Even if the metal cover 4 can be formed, the disconnection or conduction resistance is increased, and the metal cover 4 cannot be reliably grounded to the ground potential.

(Object of invention)
An object of the present invention is to provide a surface mount oscillator that reliably recognizes the directionality from the metal cover side and reliably grounds the metal cover to the ground potential.

  According to the present invention, as shown in the claims (Claim 1), an IC chip and a crystal piece are accommodated in a container body made of a multilayer ceramic, and the IC chip and the electric chip are placed on the outer bottom surface of the container body. External terminals connected to each other are provided, and an opening end surface of the container body has a metal film electrically connected to a ground terminal in the external terminals, and a metal cover is bonded to the metal film at least as described above. In a crystal oscillator for surface mounting in which a crystal piece is hermetically sealed, and the shape viewed from the metal cover side is rectangular and point-symmetric with respect to the center, the outer surface of the container body crosses in the height direction. It has a formed depression, and the depression is formed with a conductive film electrically connected to the metal film and the ground terminal.

  In such a configuration, since the outer surface of the container body made of multilayer ceramic is provided with a recess that crosses the height direction, the planar outer shape is made asymmetric even after joining the metal cover, particularly in the length direction. The direction can be reliably recognized. Thereby, even after the surface-mounted oscillator is accommodated in the measurement jig, the orientation of the surface-mounted oscillator can be confirmed from the metal cover side, so that the characteristic deterioration and breakage of the IC chip can be prevented.

  A conductive film electrically connected to the metal film on the opening end face and the ground terminal on the bottom face is formed in the depression provided on the outer side face. Therefore, even if the surface mount oscillator is miniaturized, the metal cover can be reliably grounded to the ground potential.

(Embodiment section)
According to Claim 2 of the present invention, in Claim 1, a pair of outer faces of the container main body having a set of test terminals of a crystal resonator on the opposite set of outer faces, or an other set of outer faces of the container main body facing each other. Has a temperature compensation data write terminal. Even in these cases, the surface mount oscillator which is asymmetrical when viewed from the metal cover side can be obtained by the configuration of the first aspect.

  FIG. 1 is a diagram of a surface-mount oscillator for explaining an embodiment of the present invention. FIG. 1 (a) is a partially broken sectional view, FIG. 1 (b) is a plan view excluding a metal cover and a metal ring. Figure (c) is a bottom 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.

  As described above, the surface mount oscillator has the IC chip 2 by flip chip bonding fixed to the inner bottom surface of the container body 1 made of a multilayer ceramic, and both ends of the crystal piece 3 from which the extraction electrode extends are fixed to the inner wall step. The metal cover 4 is covered and hermetically sealed. On the outer bottom surface of the container body 1, there are external terminals 5 for surface mounting that are electrically connected to the IC chip 2. The opening end face has a metal film 6 electrically connected to the ground terminal in the external terminal 5 by a via hole, and a metal ring for seam welding to which the metal cover 4 is joined is brazed.

  In this example, the IC chip 2 also integrates the oscillation circuit and the temperature compensation mechanism to make the surface mount oscillator a temperature compensation type. The circuit function surface, which is one main surface of the IC chip 2, has IC terminals including crystal terminals that are flip-chip bonded, and the power supply, output, ground, and AFC terminal are externally connected to these through the laminated surface. Electrically connected to terminal 5. A write terminal 8a for writing temperature compensation data is provided on the outer surface of the container body 1 and is connected to the corresponding IC terminal. Also in this example, two dedicated write terminals 8a are provided on a pair of outer surfaces facing each other in the long side direction.

  The quartz piece 3 is electrically connected to the crystal terminal of the IC chip 2 by fixing both ends of the extended end portion of the extraction electrode to the crystal terminal of the inner wall stepped portion by the conductive adhesive 9 or the like. Here, the crystal terminal of the inner wall step portion also extends as a crystal inspection terminal 8b on the outer surface of another set facing each other in the short side direction. The crystal inspection terminal 8b and the write terminal 8a are formed except for the uppermost layer and the lowermost layer of the multilayer ceramic in order to prevent an electrical short circuit.

  A pair of opposing outer surfaces of the container body 1 is provided with a writing terminal 8a on the surface of the recess leaving the above-mentioned uppermost layer by through-hole processing in the state of a sheet-like substrate. In this embodiment, one write terminal 8a provided on a pair of opposed outer surfaces is one end side in the long side direction, and the other write terminal 8a is the central portion as described above.

  Then, on one outer surface of the pair of opposing outer surfaces, a recess 10 is provided on the other end side in the long side direction by the same through-hole processing to form a conductive film 11. Here, the recess 10 is formed across the height direction of the outer surface of the container body 1. In short, a set of outer surfaces is provided with a recess penetrating in the thickness direction (hereinafter referred to as a through recess 10).

  The conductive film 11 is electrically connected to a ground terminal in the mounting electrode through a conductive path (not shown), and further electrically connected to the metal film 6 on the opening end surface to which the metal cover 4 is joined. In addition, a crystal inspection terminal 8b having a depression is provided on the outer surface of another set in the container body 1 except for the uppermost layer described above.

  With such a configuration, even after the metal cover 4 is joined to the opening end surface of the container body 1, the through-hole 10 provided on the outer surface of the container body 1 can be recognized from the metal cover side. And the penetration hollow 10 makes the point symmetry centering on a rectangular shape asymmetrical when it sees from the metal cover 4 side (FIG. 2).

  Therefore, even after the surface mount oscillator covered with the metal cover 4 before product display is accommodated in the measurement jig, the directivity in the length direction of the surface mount oscillator can be recognized using the through depression 10 as a guide. Thereby, when the surface mount oscillator is accommodated in the measuring jig in the reverse direction, for example, the measurement of the oscillation characteristic can be stopped and the characteristic deterioration or breakage of the IC chip 2 can be prevented. Then, it is possible to measure only the oscillation characteristics of the correctly mounted surface-mount oscillator. Thereafter, the product is displayed on the metal cover 4 of the surface mount oscillator, which is a good product, by printing or the like.

  Further, in this example, a conductive film 11 connected to the metal film 6 on the opening end face and the ground terminal in the external terminal 5 is formed in the through recess 10. Therefore, even if the downsizing of the surface mount oscillator is promoted and the conductivity of the electrode through hole 7 is impaired, the conductive film 11 can reliably ground the metal film 6 (metal cover 4) to the ground potential. It goes without saying that the via hole may be eliminated and only the conductive film 11 may be used.

(Other matters)
In the above embodiment, the crystal inspection terminal 8b and the write terminal 8a have depressions except for the uppermost layer. However, as shown in FIG. 3, even if these uppermost layers penetrate through the depressions, The through-hole 10 in the present invention is asymmetric when viewed from the metal cover 4 side. Therefore, the crystal inspection terminal 8b and the write terminal 8a may be recessed to penetrate the outer surface. In short, the present invention can be applied to a shape that is point-symmetric when viewed from the metal cover 4 side.

  Moreover, although the penetration recess 10 is only one place, it can be provided at a plurality of places to make it easier to recognize asymmetry. The container body 1 has a concave shape having inner wall step portions. For example, even when the main body 1 has concave portions on both main surfaces, the crystal piece 3 is accommodated in one side and hermetically sealed, and the IC chip 2 is accommodated in the other side. The same applies.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the surface mount oscillator explaining one Embodiment of this invention, The figure (a) is sectional drawing of a partially broken figure, The figure (b) is a top view except a metal cover and a metal ring, The figure (c). Is a bottom view. It is a top view of the surface mount oscillator in one Embodiment of this invention. It is a top view of the surface mount oscillator explaining the other application example of this invention. It is a figure of the surface mount oscillator explaining a prior art example, the figure (a) is a partially broken sectional view, the figure (b) is a plan view excluding a metal cover and a metal ring, and the figure (c) is a bottom view. is there. It is a top view of the surface mount oscillator in a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 IC chip, 3 Crystal piece, 4 Metal cover, 5 External terminal, 6 Metal film, 7 Electrode through-hole, 8a Write terminal, 8b Crystal inspection terminal, 9 Conductive adhesive, 10 Through-dimple, 11 Conductive film, 12 bumps.

Claims (2)

  An IC chip and a crystal piece are accommodated in a container body made of a multilayer ceramic, an external terminal electrically connected to the IC chip is provided on the outer bottom surface of the container body, and the opening end surface of the container body has the above-mentioned It has a metal film electrically connected to the ground terminal in the external terminal, a metal cover is bonded to the metal film, and at least the crystal piece is hermetically sealed, and the shape viewed from the metal cover side is rectangular In a surface-mount crystal oscillator that is point-symmetric with respect to the center, the outer surface of the container body has a recess formed transversely in the height direction, and the metal film and the ground terminal are provided in the recess. A crystal oscillator for surface mounting in which a conductive film electrically connected to is formed.   2. The temperature compensation data writing terminal according to claim 1, wherein a pair of outer side faces of the container main body have inspection terminals for crystal resonators, and another pair of outer side faces of the container main body face each other. Surface mount crystal oscillator with