JP2009296302A - Piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator made thin in height. <P>SOLUTION: A crystal oscillator 1 is provided with a crystal vibrator 10, an oscillating element 20 constituting an oscillation circuit for vibrating the crystal vibrator 10, at least one heating element 30, and a circuit board 40 with respective components mounted thereon. The circuit board 40 has a plurality of through-holes 43 in a range overlapping the crystal vibrator 10 in a planar view, wherein a solder 44 whose heat conductivity is higher than that of the circuit board 40 fills the plurality of through-holes 43, the circuit board 40 and the crystal vibrator 10 are brought into close contact with each other through the solder 44, and the circuit board 40 and the crystal vibrator 10 heated by the heating element 30 are thermally coupled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric oscillator, and more particularly to a piezoelectric oscillator with high frequency stability.

Conventionally, a piezoelectric oscillator of a type that suppresses frequency changes by maintaining a substantially constant temperature by heating a piezoelectric vibrator, etc., has high frequency stability. Used in communication equipment.
Regarding a crystal oscillator as a piezoelectric oscillator of this type, a crystal oscillator, an oscillation element, a heating supply comprising a heating chip resistor and a heat conducting plate, a circuit board on which these are mounted, and a heating chip resistor and There is known a configuration in which a thermally coupled heat conducting plate is directly thermally coupled to a quartz resonator (for example, see Patent Document 1).

JP 2005-333315 A

The crystal oscillator (hereinafter referred to as a piezoelectric oscillator) is disposed close to a heating chip resistor (hereinafter referred to as a heating element) mounted on a circuit board, so that a heat conducting plate thermally coupled to the heating element is provided. By being disposed so as to face a crystal resonator (hereinafter referred to as a piezoelectric resonator), it is thermally coupled to the piezoelectric resonator (see FIG. 1 of Patent Document 1).
According to this, since the piezoelectric oscillator has a laminated structure in which the heat conducting plate is disposed between the circuit board and the piezoelectric vibrator, compared to the case where the piezoelectric vibrator is mounted so as to be in direct contact with the circuit board. Thus, there is a problem that the height dimension from the circuit board to the tip of the piezoelectric vibrator is increased by the thickness of the heat conducting plate.

In the piezoelectric oscillator, an oscillating element that oscillates the piezoelectric vibrator is mounted on the other main surface of the circuit board opposite to the one main surface thermally coupled to the heat conducting plate.
As a result, in the piezoelectric oscillator, heat conduction to the oscillation element mounted on the other main surface of the circuit board is performed from one main surface thermally coupled to the heat conducting plate through the inside of the circuit board and the other main surface. The
From this, the thermal conductivity to the oscillation elements mounted on the other main surface of the circuit board generally depends on the thermal conductivity of the circuit board, which is significantly lower than that of the heat conducting plate. This is inferior to the thermal conductivity to the mounted piezoelectric vibrator.
Therefore, in the piezoelectric oscillator, it takes time until an oscillation element mounted on the other main surface of the circuit board becomes substantially constant temperature compared to a piezoelectric vibrator mounted on one main surface, or There is a problem that it is difficult to become a substantially constant temperature state.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A piezoelectric oscillator according to this application example includes a piezoelectric vibrator, an oscillation element that constitutes an oscillation circuit that oscillates the piezoelectric vibrator, at least one heating element, and each of the components. A circuit board, and the circuit board has a plurality of through holes or recesses in a range overlapping with the piezoelectric vibrator in plan view, and the thermal conductivity of the plurality of through holes or recesses from the circuit board Filled with a high heat conduction member, the circuit board and the piezoelectric vibrator are in close contact with each other through the heat conduction member, and the circuit board and the piezoelectric vibrator heated by the heating element are thermally coupled. It is characterized by being.

According to this configuration, the piezoelectric oscillator includes the piezoelectric vibrator, the oscillation element, the heating element, and the circuit board, and the circuit board has a plurality of through holes or recesses in a range overlapping the piezoelectric vibrator in a plan view. ing. In the piezoelectric oscillator, a plurality of through holes or recesses are filled with a heat conduction member having a higher thermal conductivity than the circuit board, and the circuit board and the piezoelectric vibrator are in close contact with each other through the heat conduction member, and are heated by a heating element. The printed circuit board and the piezoelectric vibrator are thermally coupled.
As a result, the piezoelectric oscillator efficiently heat-couples the circuit board and the piezoelectric vibrator through the heat conducting member and maintains the substantially constant temperature state of the piezoelectric vibrator. Is unnecessary, and the height dimension from the circuit board to the tip of the piezoelectric vibrator can be made smaller than in the prior art. Therefore, the piezoelectric oscillator can be further reduced in height.

In addition, since the piezoelectric oscillator has a plurality of through holes or recesses filled with a heat conductive member having a higher thermal conductivity than that of the circuit board, for example, a heating element is mounted via the heat conductive member. The thermal conductivity from one main surface to the other main surface on the opposite side is improved.
As a result, the piezoelectric oscillator can shorten the time until an element mounted on the other main surface of the circuit board, for example, an oscillation element, is in a substantially constant temperature state, or can easily become a substantially constant temperature state. it can.
Therefore, the piezoelectric oscillator can improve frequency stability.

  Further, in the piezoelectric oscillator, when the concave portion is provided on the circuit board, the component mounting area on any one of the main surfaces without the concave portion can be widened as compared with the case where the through hole is provided.

  Application Example 2 In the piezoelectric oscillator according to the application example described above, the piezoelectric oscillator is formed on the inner layer of the circuit board over substantially the entire range overlapping with the piezoelectric vibrator in a plan view, and filled into the plurality of through holes or recesses. In addition, it is preferable that a metal layer that is in contact with or close to the heat conducting member is formed.

According to this configuration, the piezoelectric oscillator is formed on the inner layer of the circuit board over substantially the entire range overlapping with the piezoelectric vibrator in plan view, and the metal layer in contact with or close to the heat conducting member is formed. .
As a result, the piezoelectric oscillator has a metal layer formed on the inner layer of the circuit board, thereby improving the thermal conductivity in the circuit board. Thus, the piezoelectric oscillator mounted on the circuit board, an oscillation element, etc. This further improves the heat conduction.
Therefore, since the piezoelectric oscillator can maintain a substantially constant temperature state, the frequency stability can be further improved.

  Application Example 3 In the piezoelectric oscillator according to the application example described above, it is preferable that the plurality of through holes of the circuit board are through holes in which a metal film is formed on a side wall, and the heat conducting member is solder.

According to this configuration, in the piezoelectric oscillator, the plurality of through holes of the circuit board are through holes in which the metal film is formed on the side wall, and the heat conducting member is solder. For this reason, in the piezoelectric oscillator, for example, solder having extremely high thermal conductivity as compared with a circuit board made of a glass epoxy substrate is filled to every corner of the through hole due to wettability.
Thus, the piezoelectric oscillator can thermally couple the circuit board and the piezoelectric vibrator more efficiently by using solder as the heat conducting member.
Therefore, the piezoelectric oscillator can further improve the frequency stability.

  Application Example 4 In the piezoelectric oscillator according to the application example described above, it is preferable that the heat conducting member is a resin.

According to this configuration, since the heat conduction member is a resin, the piezoelectric oscillator can be easily filled into a plurality of through holes or recesses by a dispenser or the like by using, for example, a paste-like resin. Can be improved.
In addition, the piezoelectric oscillator can simplify the manufacturing process by selecting a resin that does not need to be heated at the time of filling, as compared with solder that requires heating.

  Application Example 5 In the piezoelectric oscillator according to the application example described above, the heating element is mounted on the other main surface of the circuit board opposite to the one main surface on which the piezoelectric vibrator is mounted, and the penetration It is preferably located in the vicinity of the hole.

According to this configuration, in the piezoelectric oscillator, the heating element is mounted on the other main surface opposite to the one main surface of the circuit board, and is positioned in the vicinity of the through hole.
As a result, the piezoelectric oscillator eliminates the heating element escape portion of the piezoelectric vibrator, which is necessary when, for example, the piezoelectric vibrator is arranged so as to overlap the heating element in plan view on the one main surface side.
Thus, the piezoelectric oscillator can reduce the thickness of the piezoelectric vibrator by the heating element escape portion. Therefore, the piezoelectric oscillator can be further reduced in height.
In addition, since the heating element is located in the vicinity of the through-hole, the piezoelectric oscillator promptly passes from the other main surface of the circuit board to the one main surface and the piezoelectric vibrator via the heat conducting member filled in the through-hole. Heat conduction is performed.
As a result, the piezoelectric oscillator can satisfactorily thermally couple the circuit board and the piezoelectric vibrator even when the heating element and the piezoelectric vibrator are not mounted on the same main surface of the circuit board.

  Application Example 6 In the piezoelectric oscillator according to the application example described above, it is preferable that the plurality of through holes or recesses are formed in a shape along the outer shape of the piezoelectric vibrator in a plan view.

  According to this configuration, since the plurality of through holes or recesses are formed in a shape along the outer shape of the piezoelectric vibrator in a plan view, the piezoelectric oscillator has a heat filled in the plurality of through holes or recesses. The circuit board and the piezoelectric vibrator can be thermally coupled more efficiently via the conductive member.

  Hereinafter, embodiments of a piezoelectric oscillator will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram showing a schematic configuration of a crystal oscillator as an example of a piezoelectric oscillator. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view of the main part. In the plan view, the metal cover is omitted for easy understanding, and the outline of the metal cover is indicated by a two-dot chain line.

  As shown in FIG. 1, the crystal oscillator 1 of the present embodiment includes a crystal resonator 10 as a piezoelectric resonator, an oscillation element 20, a heating element 30, a circuit board 40, a metal base 50, a metal cover 60, and the like. ing.

In the crystal oscillator 1, a box-shaped metal cover 60 formed so as to cover the circuit board 40 supported above the metal base 50 is joined to the metal base 50 to form a substantially rectangular parallelepiped shape.
The circuit board 40 has a substantially rectangular shape in plan view, and the bottom surface of the metal base 50 is formed by a plurality of metal pins 51 as external terminals that penetrate the metal base 50 having a substantially planar shape in an insulated state. It is supported so as to be substantially parallel. In addition, the circuit board 40 is supported only by the metal pin 51, so that heat radiation to the outside due to heat conduction is suppressed.

The crystal resonator 10 is mounted on one main surface 41 of the circuit board 40. In the crystal resonator 10, for example, a crystal vibrating piece (not shown) such as an AT cut or an SC cut is hermetically sealed in a substantially cylindrical metal container 12 from which five lead wires 11 are led out from the bottom surface.
The crystal unit 10 is fixed to the circuit board 40 via the lead wire 11 with solder or the like.

A heating element 30 is mounted on a range of the main surface 41 of the circuit board 40 that overlaps the crystal unit 10 in plan view.
The heating element 30 is disposed so as to be accommodated in a stepped portion 13 (heating element escape portion) between the flange portion 14 on the outer periphery of the crystal unit 10 and the bottom surface on the inside. Thereby, the heating element 30 avoids interference with the crystal unit 10. Note that a chip resistor, a power transistor, or the like is used for the heating element 30 and generates heat due to Joule heat.
The amount of heat generated by the heating element 30 is adjusted by a temperature control circuit using a temperature sensing element such as a thermistor (not shown) and a DC control transistor so that the crystal unit 10 and the like are in a substantially constant temperature state at a constant temperature. Yes. A plurality of heating elements 30 may be mounted. The heating element 30 may be disposed around the crystal resonator 10.

  On the other main surface 42 of the circuit board 40, the oscillation element 20 constituting the oscillation circuit for oscillating the crystal resonator 10 is mounted. For the oscillation element 20, a transistor, a chip resistor, a chip capacitor, or the like is used. The crystal resonator 10 oscillates at a predetermined frequency by this oscillation circuit.

The circuit board 40 has a plurality of through holes 43 in a range overlapping with the crystal resonator 10 in plan view. The through hole 43 is formed in a substantially arc shape along the outer shape of the collar portion 14 on the outer periphery of the crystal resonator 10.
The through hole 43 is a through hole in which a metal film is formed on the side wall. The through hole 43 is filled with, for example, solder 44 as a heat conductive member having a higher thermal conductivity than the circuit board 40 made of a glass epoxy substrate. As an example, the thermal conductivity of the glass epoxy substrate is about 0.2 W / mK, and the thermal conductivity of the solder 44 is about 50 to 60 W / mK, depending on the composition.

At this time, cream-like solder is used as the solder 44, and after the quartz crystal resonator 10 is mounted, the through holes 43 are collectively applied to the mounting land such as the oscillation element 20 formed on the circuit board 40. The inside is filled. Thereby, the crystal oscillator 1 is efficiently filled with the solder 44 as the heat conducting member.
The solder 44 filled in the through-hole 43 wets and spreads to every corner in the through-hole 43 due to wettability with the metal film formed on the side wall during heating by reflow mounting of the oscillation element 20 or the like. Furthermore, the solder 44 wets and spreads on the collar portion 14 of the crystal unit 10 that overlaps the through hole 43 in plan view.

As a result, the crystal oscillator 1 has an air layer whose thermal conductivity is lower than that of the circuit board 40 due to the circuit board 40 and the collar portion 14 of the crystal unit 10 being in close contact with each other through the wet solder 44. It is excluded from between the substrate 40 and the collar portion 14 of the crystal unit 10.
Accordingly, the crystal oscillator 1 is in a state where the circuit board 40 heated by the heating element 30 that has generated heat and the crystal unit 10 are efficiently thermally coupled.
In the crystal oscillator 1, as described above, the amount of heat generated by the heating element 30 is adjusted by the temperature control circuit, so that the crystal resonator 10 that is thermally coupled to the circuit board 40 is maintained in a substantially constant temperature state at a constant temperature. Be drunk.

  A slit-shaped through hole 45 is formed on the outer peripheral side of the through hole 43 of the circuit board 40 so as to surround the through hole 43. Thereby, the crystal oscillator 1 thermally separates a portion (a portion substantially overlapping with the crystal resonator 10 in a plan view) and an outer peripheral portion of the circuit board 40 that are thermally coupled to the crystal resonator 10, The heat radiation of the portion of the substrate 40 that is thermally coupled to the crystal unit 10 can be suppressed.

  As described above, in the crystal oscillator 1 of the present embodiment, the circuit board 40 has the plurality of through holes 43 in a range where the circuit board 40 overlaps the crystal resonator 10 in plan view. In the crystal oscillator 1, the plurality of through holes 43 are filled with solder 44 having a thermal conductivity higher than that of the circuit board 40, and the circuit board 40 and the crystal unit 10 are in close contact with each other through the solder 44, thereby heating element 30. The circuit board 40 and the crystal unit 10 heated by the heat are thermally coupled.

Thereby, in the crystal oscillator 1, the circuit board 40 and the crystal unit 10 are efficiently thermally coupled via the solder 44 whose thermal conductivity is higher than that of the circuit board 40, so that the crystal unit 10 has a substantially constant temperature state. Keeps good.
For this reason, the crystal oscillator 1 does not require the heat conducting plate conventionally provided between the circuit board 40 and the crystal oscillator 10, and the height dimension H from the circuit board 40 to the tip of the crystal oscillator 10 is reduced. It can be made smaller than before. Therefore, the crystal oscillator 1 can be further reduced in height as compared with the prior art.

In the crystal oscillator 1, a plurality of through holes 43 are filled with solder 44 having a higher thermal conductivity than that of the circuit board 40. From this, the crystal oscillator 1 has the conventional thermal conductivity from the one main surface 41 of the circuit board 40 on which the heating element 30 is mounted to the other main surface 42 on the opposite side through the solder 44. Compared to the configuration of the substrate 40 alone, the improvement is achieved.
Thereby, the crystal oscillator 1 can shorten the time until the oscillation element 20 mounted on the other main surface 42 of the circuit board 40 is in a substantially constant temperature state, or can easily be in a substantially constant temperature state. it can.
Therefore, the crystal oscillator 1 can improve the frequency stability.

In addition, the crystal oscillator 1 uses the solder 44 having a thermal conductivity much higher than that of the resin, so that the circuit board 40 and the crystal unit 10 are thermally coupled more efficiently than when the resin is used as the heat conductive member. be able to.
Therefore, the crystal oscillator 1 can further improve the frequency stability as compared with the case where a resin is used for the heat conducting member.

  Further, in the crystal oscillator 1, the plurality of through holes 43 are formed in an arc shape along the outer shape of the crystal resonator 10 in a plan view, and thus the solder 44 filled in the plurality of through holes 43 is interposed therebetween. Thus, the circuit board 40 and the crystal unit 10 can be thermally coupled more efficiently as compared with other shapes.

In this embodiment, the solder 44 is used as the heat conducting member, but the present invention is not limited to this, and a resin may be used. According to this, the crystal oscillator 1 can easily fill the plurality of through holes 43 with a dispenser or the like by using the paste-like resin as the heat conducting member, and can improve workability.
Examples of the paste-like resin include a silicone resin adhesive containing a conductive filler, a silicone resin grease used for joining a CPU and its cooling heat sink, and the like.

Further, the crystal oscillator 1 can simplify the manufacturing process by selecting a resin that does not need to be heated at the time of filling, as compared with the solder 44 that requires heating.
In addition, since the crystal oscillator 1 uses a resin as a heat conducting member, it is not necessary to make the through hole 43 a through hole, and therefore the processing man-hour of the circuit board 40 can be reduced.
In addition, when using resin as a heat conductive member, it is preferable to fill so that resin may not protrude from the other main surface 42 of the circuit board 40. FIG. Thereby, the crystal oscillator 1 can avoid the outflow of the resin onto the other main surface 42.

  In the present embodiment, the shape of the plurality of through-holes 43 is an arc shape along the outer shape of the crystal unit 10, but is not limited thereto, and is not limited to a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape. It is good also as a shape.

Here, the modification of the said embodiment is demonstrated with reference to drawings.
(Modification 1)
FIG. 2 is a cross-sectional view of a principal part showing a schematic configuration of a crystal oscillator according to Modification 1 of the embodiment. In addition, the same code | symbol is attached | subjected to a common part with the said embodiment, and the description is abbreviate | omitted.

As shown in FIG. 2, the crystal oscillator 101 according to the first modification is formed on the inner layer of the circuit board 140 over substantially the entire range that overlaps the crystal resonator 10 in plan view, and is filled in the plurality of through holes 43. A solid metal layer 146 in contact with or close to the solder 44 is formed.
Note that a copper foil or the like is used for the metal layer 146. In addition, a through hole larger than the diameter of the lead wire 11 is provided at a portion where the metal layer 146 intersects the lead wire 11 of the crystal unit 10 to avoid contact with the lead wire 11.

According to this, the crystal oscillator 101 has the solid metal layer 146 formed on the inner layer of the circuit board 140, so that the heat conducted from the one main surface 41 of the circuit board 140 to the inside of the circuit board 140 is By reaching the metal layer 146 having a high thermal conductivity, the entire metal layer 146 is rapidly conducted.
The heat conducted to the metal layer 146 is conducted quickly because the metal layer 146 is in contact with or close to the solder 44 filled in the plurality of through holes 43. On the other hand, since the heat conducted to the metal layer 146 is conducted from the entire metal layer 146 toward the other main surface 42, compared with the case without the metal layer 146, the heat from the one main surface 41 to the other main surface 42. Heat conduction to the surface 42 is accelerated.

As a result, the crystal oscillator 101 has improved thermal conductivity in the circuit board 140, so that the heat conduction to the crystal resonator 10 and the oscillation element 20 mounted on the circuit board 140 is further improved.
Therefore, the crystal oscillator 101 can further improve the frequency stability because the substantially constant temperature state of the crystal resonator 10 and the like is kept better.
Note that the metal layer 146 may be formed not only in a solid shape but also in a mesh shape.

(Modification 2)
FIG. 3 is a cross-sectional view of a main part showing a schematic configuration of a crystal oscillator according to a second modification of the embodiment. In addition, the same code | symbol is attached | subjected to a common part with the said embodiment, and the description is abbreviate | omitted.

As shown in FIG. 3, in the crystal oscillator 201 according to the second modification, a concave portion 243 is formed on one main surface 41 of the circuit board 240 instead of the through hole 43 (see FIG. 1) of the above-described embodiment. ing. In addition, the planar shape of the recessed part 243 is the same as that of the through-hole 43 of the said embodiment. Further, the recess 243 is filled with the solder 44 as in the above embodiment.
In this case, the procedure is to mount the crystal unit 10 after the solder 44 is filled in the concave portion 243 of the circuit board 240 first.

According to this, in the crystal oscillator 201, since the concave portion 243 is formed in the circuit board 240, the component mounting area of the other main surface 42 without the concave portion 243 is wider than in the case where the through hole is formed. can do.
As described above, the heat conductive member is not limited to the solder 44, and may be a resin having a higher heat conductivity than the circuit board 240.

(Modification 3)
FIG. 4 is a cross-sectional view of a principal part showing a schematic configuration of a crystal oscillator according to a third modification of the embodiment. In addition, the same code | symbol is attached | subjected to a common part with the said embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 4, in the crystal oscillator 301 of the third modification, the heating element 30 is mounted on the other main surface 42 opposite to the one main surface 41 on which the crystal resonator 310 of the circuit board 40 is mounted. At the same time, it is located in the vicinity of the through hole 43.

According to this, since the crystal oscillator 301 is not mounted with the heating element 30 and the crystal oscillator 310 overlapped with each other, the step portion 13 (the heating element escape portion, FIG. 1) becomes unnecessary.
Thus, the crystal oscillator 301 can reduce the thickness of the crystal unit 310 by the level difference. Thereby, the crystal oscillator 301 can make the height dimension H from the circuit board 40 to the front-end | tip of the crystal oscillator 310 smaller than the said embodiment.
Therefore, the crystal oscillator 301 can be further reduced in height.

In the crystal oscillator 301, since the heating element 30 is located in the vicinity of the through hole 43 of the other main surface 42, the heat of the heating element 30 is quickly conducted to the solder 44 filled in the through hole 43, Thermal conduction is efficiently performed from the other main surface 42 of the circuit board 40 to the one main surface 41 and the crystal unit 310 through the solder 44.
As a result, the crystal oscillator 301 can satisfactorily thermally couple the circuit board 40 and the crystal oscillator 310 even when the heating element 30 and the crystal oscillator 310 are not mounted on the same main surface of the circuit board 40.

  In the above-described embodiment and each modified example, a description has been given by taking a crystal oscillator using a crystal as a piezoelectric vibrator as an example of the piezoelectric oscillator, but the present invention is not limited to this, and the piezoelectric vibrator includes lithium tantalate and niobate. A piezoelectric oscillator using lithium or the like may be used.

The block diagram which shows schematic structure of the crystal oscillator as an example of the piezoelectric oscillator of this embodiment. The principal part sectional view showing the schematic structure of the crystal oscillator of modification 1 of the above-mentioned embodiment. The principal part sectional drawing which shows schematic structure of the crystal oscillator of the modification 2 of the said embodiment. The principal part sectional view showing the schematic structure of the crystal oscillator of modification 3 of the above-mentioned embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Crystal oscillator as a piezoelectric oscillator, 10 ... Crystal oscillator as a piezoelectric vibrator, 11 ... Lead wire, 12 ... Metal container, 13 ... Step part, 14 ... Brim part, 20 ... Oscillating element, 30 ... Heating element DESCRIPTION OF SYMBOLS 40 ... Circuit board 41 ... One main surface 42 ... Other main surfaces 43 ... Through-hole 44 ... Solder as a heat conductive member 45 ... Through-hole 50 ... Metal base 51 ... Metal pin 60 ... Metal cover.

Claims (6)

A piezoelectric vibrator, an oscillation element that constitutes an oscillation circuit that oscillates the piezoelectric vibrator, at least one heating element, and a circuit board on which each of the components is mounted,
The circuit board has a plurality of through holes or recesses in a range overlapping the piezoelectric vibrator in plan view,
The plurality of through holes or recesses are filled with a heat conductive member having a higher thermal conductivity than the circuit board, and the circuit board and the piezoelectric vibrator are in close contact with each other through the heat conductive member,
The piezoelectric oscillator, wherein the circuit board heated by the heating element and the piezoelectric vibrator are thermally coupled.   2. The piezoelectric oscillator according to claim 1, wherein the heat conduction is formed on an inner layer of the circuit board substantially in a range overlapping with the piezoelectric vibrator in a plan view and filled in the plurality of through holes or recesses. 3. A piezoelectric oscillator, characterized in that a metal layer is formed on or in contact with a member.   3. The piezoelectric oscillator according to claim 1, wherein the plurality of through holes of the circuit board are through holes in which a metal film is formed on a side wall, and the heat conducting member is solder. Oscillator.   3. The piezoelectric oscillator according to claim 1, wherein the heat conducting member is a resin.   5. The piezoelectric oscillator according to claim 1, wherein the heating element is mounted on the other main surface of the circuit board opposite to the one main surface on which the piezoelectric vibrator is mounted. The piezoelectric oscillator is located in the vicinity of the through hole.   The piezoelectric oscillator according to any one of claims 1 to 5, wherein the plurality of through holes or recesses are formed in a shape along an outer shape of the piezoelectric vibrator in a plan view. Piezoelectric oscillator.

Images