JP2010187263A - Surface mount crystal oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface mount oscillator which prevents frequency variation during power-on. <P>SOLUTION: A surface mount crystal oscillator comprises: a container body 1 which has concave parts on both principal surfaces by layering frame walls 1 (bc) on the both principal surfaces of a bottom wall 1a; a crystal piece 2 whose one end having both sides where lead electrodes 10 (ab) are drawn out, is fixed to a pair of crystal holding terminals 5 (ab) provided on the inner bottom surface of one concave part of the container body 1; a metal cover 4 which is bonded to the end face of an opening of the one concave part to seal the crystal piece 2; and an IC chip 3 having an IC terminal electrically and mechanically connected to a circuit terminal 7 provided on the inner bottom surface of the other concave part of the container body 1. In the surface mount crystal oscillator, the crystal holding terminals 5 (ab) have an electrode for heat dissipation 14 extending to the inner bottom surface of the container body 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 prevents a change in oscillation frequency due to heat generation of an IC chip housed together with a crystal piece.

(Background of the Invention)
Since the surface-mounted oscillator is small and light, it is particularly built in a portable electronic device represented by a mobile phone. As one of such devices, there is one in which a container body has a cross-sectional H shape having recesses on both main surfaces, a crystal piece is accommodated in one recess, and an IC chip is accommodated in the other recess.

  FIG. 4 is a view of a surface-mount oscillator for explaining a conventional example, in which FIG. 4 (a) is a sectional view and FIG. 4 (b) is a plan view excluding a metal cover and the like.

  The surface-mount oscillator includes a container body 1, a crystal piece 2, an IC chip 3, and a metal cover 4. The container body 1 is made of a laminated ceramic, has a bottom wall 1a and frame walls 1 (bc) on both main surfaces, and has a cross-sectional H shape with recesses on both main surfaces as described above. The container body 1 has a pair of crystal holding terminals 5 (ab) on the bottom surface in one recess, and a plurality of circuit terminals 7 on the bottom surface in the other recess.

  The pair of crystal holding terminals 5 (ab) are electrically connected to the pair of crystal terminals 7 (xy) in the circuit terminals 7 by a wiring path 6 by a via hole or the like provided in the bottom wall 1a. The power supply, output, ground, and, for example, the AFC terminal in the circuit terminal 7 are electrically connected to the mounting terminal 8 provided on the outer bottom surface (four corners) of the container body 1 through a wiring path (not shown).

  The crystal piece 2 is, for example, an AT cut, and the extraction electrode 10 (ab) extends from the excitation electrode 9 (ab) on both main surfaces to both sides of one end. Each extraction electrode 10 (ab) is formed, for example, by being folded back on the opposite surface. Both ends of one end of the crystal piece 2 from which the extraction electrode 10 (ab) extends are fixed to the crystal holding terminal 5 (ab) on the inner bottom surface by a conductive adhesive 11 or the like, and are electrically and mechanically connected.

  The IC chip 3 includes at least an oscillation circuit. In this example, the IC chip 3 includes a temperature compensation mechanism that compensates for a frequency temperature characteristic caused by the crystal resonator. Then, an IC terminal on one main surface serving as a circuit function surface (circuit forming surface) is fixed to the circuit terminal 7 on the bottom surface in the other recess by, for example, ultrasonic thermocompression using a bump 12 (so-called flip chip bonding). Connect electrically and mechanically. In addition, the code | symbol 13 in a figure is a metal ring, and the metal cover 4 is joined by seam welding.

  In such a case, the frequency-temperature characteristic is based on a crystal resonator, as shown in FIG. 5 (curve A), the inflection point at room temperature 25 ° C., the minimum value on the high temperature side, and the maximum value on the low temperature side. Becomes a cubic curve. Then, a temperature compensation voltage depending on the temperature from the temperature compensation mechanism is applied to the voltage variable capacitance element inserted in the oscillation circuit, and the series equivalent capacitance (load capacitance) seen from the crystal resonator is changed. Thus, the temperature compensation is performed by canceling the frequency temperature characteristic by the frequency voltage characteristic (curve (b) in FIG. 5) depending on the temperature compensation voltage.

JP2008-311826

(Problems of conventional technology)
However, in the surface mount oscillator having the above configuration, the temperature rapidly rises due to heat generation of the active element of the IC chip 3 when the power is turned on. In particular, heat is transferred to the crystal piece 2 through the crystal terminal in the IC terminal, the circuit terminal 7 (xy), the wiring path 6 and the crystal holding terminal 5 (ab). Furthermore, heat is transferred from the extraction electrode 10 (ab) directly connected to the crystal holding terminal 5 (ab) to the excitation electrode 9 (ab) by the conductive adhesive 11. In other words, the heat generation temperature of the IC chip 3 is changed to the crystal piece 2. Heat is transferred directly to the vibration region “excitation electrode 9 (ab)”. Further, heat from the bottom wall 1a is also transferred to the vibration region through the space.

  At this time, it takes time for the temperature state of the IC chip 3 and the crystal piece 2 to reach the thermal equilibrium state. There is a problem that the frequency change (fluctuation) is worsened mainly due to the temperature change until the thermal equilibrium is reached.

(Object of invention)
It is an object of the present invention to provide a surface mount oscillator that prevents frequency fluctuations when power is turned on.

  According to the present invention, as described in the claims (Claim 1), a container body having frame walls laminated on both main surfaces of a bottom wall and having recesses on both main surfaces, and one recess of the container body A crystal piece in which both ends of the extraction electrode are fixed to a pair of crystal holding terminals provided on the inner bottom surface, and a metal cover that seals and encloses the crystal piece by bonding to the opening end face of the one recess. A surface-mount crystal oscillator comprising an IC chip having an IC terminal electrically and mechanically connected to a circuit terminal provided on the bottom surface of the other concave portion of the container body. The crystal holding terminals to be connected to each other have a heat radiation electrode extending to the inner bottom surface of the container body.

  With such a configuration, in particular, the crystal holding terminal electrically connected to the crystal terminal of the IC terminal extends the heat radiation electrode to the inner bottom surface of the container body. Therefore, the heat generation temperature of the IC chip is directly transferred to the crystal holding terminal through a wiring path electrically connected to the crystal terminal of the IC terminal, and further transferred to the heat radiation electrode. As a result, the heat generation temperature of the IC chip is radiated from the heat radiation electrode and suppresses a rapid temperature rise of the crystal piece, so that it is possible to prevent frequency fluctuations when the power is turned on.

(Embodiment section)
According to a second aspect of the present invention, in the first aspect, the heat radiation electrode is provided in an outer region of the crystal piece. Thereby, since the radiant heat from the electrode for heat dissipation does not directly transfer to the crystal piece, a rapid temperature rise is further suppressed.

  In the third aspect of the present invention, in the first aspect, the heat radiation electrode is provided in an outer region of the excitation electrode of the crystal piece. In this case, since the radiant heat from the heat radiation electrode does not directly transfer to the vibration region excitation electrode portion of the crystal piece, a rapid temperature rise is similarly suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the surface mount oscillator explaining 1st Embodiment of this invention, The figure (a) is sectional drawing, The figure (b) is a top view except a metal cover. It is a figure explaining other examples of a 1st embodiment of the present invention, and the figure (ab) is a top view except a metal cover of a surface mount oscillator. It is a top view except the metal cover of the surface mount oscillator explaining 2nd Embodiment of this invention. It is a figure explaining a prior art example, The figure (a) is sectional drawing of a surface mount oscillator, The figure (b) is a top view except a metal cover. It is a frequency temperature of a surface mount oscillator explaining a prior art example, and a voltage characteristic.

  Hereinafter, a first embodiment of a surface-mount oscillator according to the present invention will be described with reference to FIG. 1 (cross-sectional view and plan 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 accommodates the crystal piece 2 in one concave portion of the container body 1 having an H-shaped cross section composed of the bottom wall 1a and the frame walls 1 (bc) of both main surfaces, and the other concave portion. The IC chip 3 is accommodated in the. The crystal piece 2 is fixed to the crystal holding terminal 5 (ab) on the inner bottom surface by the conductive adhesive 11 at both ends of the lead electrode 10 (ab) extending from the excitation electrode 9 (ab), and the metal cover 4 Are sealed and sealed. In addition, the IC terminal of the main surface of the IC chip 3 is fixed by ultrasonic thermocompression using the bumps 12.

  In the first embodiment, the crystal holding terminal 5 (ab) on the inner bottom surface of one recess extends the heat radiation electrode 14 (ab) on the inner bottom surface of the crystal piece 2. The heat radiation electrode 14 (ab) extends, for example, to the outer region of each long side of the crystal piece 2 (FIG. 1B). These heat radiation electrodes 14 (ab) are integrally formed when the crystal holding terminals 5 (ab) are formed. For example, the base electrode is W or Mo, and Ni and Au are sequentially plated on the surface.

  In these cases, as shown in FIG. 2 (ab), the heat radiation electrode 14 (ab) may extend from the outside of the long side of the crystal piece 2 to the outside of the other end, or alternatively, the heat radiation electrode 14 May extend from the outside of one long side of the crystal piece 2 to the outside of the other long side via the other end. However, between the tips of the heat radiation electrodes 14 (ab) or between the tips of the heat radiation electrodes 14 and the crystal holding terminals 5a is equal to or greater than that between the pair of crystal holding terminals 5 (ab). To do. This minimizes stray capacitance.

  With such a configuration, as described in the column of the effect of the invention, in particular, the crystal holding terminal 5 (ab) electrically connected to the crystal terminal of the IC terminal has the heat radiation electrode 14 in the container body 1. Extend to the bottom. Here, the heat radiation electrode 14 extends to the outer region of the crystal piece 2. Therefore, the heat generation temperature of the IC chip 3 is directly transferred to the crystal holding terminal 5 (ab) through the wiring path electrically connected to the crystal terminal of the IC terminal, and further, the heat dissipation electrode that is outside the crystal piece 2. Heat is transferred to 14.

  As a result, the radiant heat from the heat radiation electrode 14 is not directly transferred to the crystal piece 2, and the heat generation temperature of the IC chip 3 is radiated from the heat radiation electrode 14 and suppresses a rapid temperature rise of the crystal piece 2. The frequency fluctuation at power-on can be prevented.

  In these cases, since the container body 1 is sealed by the metal cover 4, the heat from the heat radiation electrode 14 is particularly generated by the metal cover 4 (for example, Ni-plated Kovar material) or the metal ring (Au-plated Kovar) to which it is joined. Material).

  In the second embodiment of the present invention (plan view of FIG. 3), the heat radiation electrode 14 (ab) extending from the pair of crystal holding terminals 5 (ab) is the lower surface of the crystal piece 2 and the excitation electrode 9 ( ab) extends across the region outside. In such a case, since the radiant heat does not directly reach the excitation electrode 9 (ab) serving as the vibration region and the area of the heat radiation electrode 14 (ab) increases, the heat radiation effect is enhanced. Therefore, it is possible to suppress a rapid temperature rise of the crystal piece 2 and prevent frequency fluctuations when the power is turned on.

1 container body, 2 crystal piece, 3 IC chip, 4 metal cover, 5 crystal holding terminal,
6 wiring path, 7 circuit terminal, 7 (xy) crystal terminal, 8 mounting terminal, 9 excitation electrode,
10 Lead electrode, 11 Conductive adhesive, 12 Bump, 13 Metal ring, 14 Heat dissipation electrode.

Claims (3)

  A container main body having frame walls stacked on both main surfaces of the bottom wall and having recesses on both main surfaces, and one end of the lead electrode extended to a pair of crystal holding terminals provided on one bottom surface of the recess of the container main body A crystal piece to which both sides are fixed, a metal cover that seals and encloses the crystal piece by joining to the opening end face of the one recess, and an IC terminal to a circuit terminal provided on the bottom surface of the other recess of the container body A crystal oscillator for surface mounting comprising an IC chip electrically and mechanically connected, wherein the crystal holding terminal has a heat radiation electrode extending to the inner bottom surface of the container body.   2. The surface-mount crystal oscillator according to claim 1, wherein the heat radiation electrode is provided in an outer region of the crystal piece.   2. The surface-mount crystal oscillator according to claim 1, wherein the heat radiation electrode is provided in an outer region of the excitation electrode of the crystal piece.

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