JP2008205886A - Highly stable piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly stable piezoelectric oscillator which prevents circuit parts on a printed circuit board from being deteriorated by heat, by means of heating a piezoelectric vibrator in a concentrated state by surrounding the piezoelectric vibrator mounted on the printed circuit board by a metal cap and by attaching a heat-generating part for heating to a metal cap periphery isolated from the printed circuit board. <P>SOLUTION: The oscillator is provided with an upper printed circuit board 10 for mounting a piezoelectric vibrator which is arranged in parallel holding a prescribed distance to an upper face of a base printed circuit board 2, the piezoelectric vibrator 20 which is mounted on a lower face of the upper printed circuit board, the metal cap 30 which surrounds a space of the lower face of the upper printed circuit board including the piezoelectric vibrator, the heat-generating part 40 which is fixed to the lower face of the metal cap in a contactless state with the upper face of the base printed circuit board, an oscillating circuit part 50 which is mounted on the upper face of the upper printed circuit board, and a metal oscillator case 70 which surrounds the space on the base printed circuit board including each part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement of a highly stable piezoelectric oscillator used as a frequency control device or the like, and particularly in a highly stable piezoelectric oscillator having a configuration in which a piezoelectric vibrator is heated by a power transistor and a heating temperature is controlled by a temperature control circuit. The present invention relates to a highly stable piezoelectric oscillator that eliminates a problem in which heat from a heat-generating component for heating a piezoelectric vibrator supported by a printed circuit board excessively heats the printed circuit board and adversely affects circuit elements on the printed circuit board.

As a piezoelectric oscillator such as a crystal oscillator, which is a frequency control device used in mobile communication equipment and transmission communication equipment, a thermostatic oven type piezoelectric oscillator that can output a highly stable frequency without being affected by external temperature changes has been conventionally used. Known from. Furthermore, in recent years, in these fields, various devices have been required to be small, light and portable, and accordingly, the thermostatic chamber type piezoelectric oscillator is required from the market to be small and light. It has been.
In order to obtain a highly stable frequency, a conventional thermostatic oven type piezoelectric oscillator houses a piezoelectric vibrator in a recess of a thermostatic oven (even) such as a metal block having a large heat capacity, and further heats the metal block to a predetermined temperature with a heater. It was heated to. However, when a large metal block is used, the bulk of the entire oscillator increases, so that it has not been possible to satisfy the demand for reduction in size and weight. In addition, since the piezoelectric vibration element inside the piezoelectric vibrator is heated via the metal block, there is a problem that it takes a long time for the heat from the heater to reach the piezoelectric vibration element and reach the desired frequency. .

As a high-stability piezoelectric oscillator that does not use a large metal block, Patent Document 1 discloses that a quartz resonator is mounted on the lower surface of a printed circuit board, and the quartz resonator is surrounded by a high-temperature bath, and is a print that is close to a thermostatic bath. A unit with heating components and a heat conducting plate mounted on the board surface is surrounded by upper and lower metal covers, and metal pins protruding downward from the printed circuit board are inserted through holes provided in the lower metal cover. An externally protruding type is disclosed.
According to this conventional example, since the heat generating component is in contact with the printed circuit board, the temperature of the heat generating component (T1), the temperature of the printed circuit board (T2), the temperature of the thermostat (T3), and the temperature of the crystal resonator (T4). ) T1>T2>T3> T4, and the printed circuit board temperature is higher than the crystal resonator temperature. In general, in a highly stable piezoelectric oscillator (OCXO) equipped with a thermostatic chamber, the temperature of the crystal resonator is set in accordance with the zero temperature coefficient of the resonator, so it is necessary to maintain the temperature at about + 80 ° C. . However, if the printed circuit board becomes higher than the set temperature of this crystal unit, the operating temperature range of the semiconductors that make up various circuit components mounted on the printed circuit board will be exceeded, or the mounted electronic components will deteriorate due to thermal aging. There is a risk of doing.
Originally, it is sufficient to heat only the crystal unit as a heat-generating component. However, if a heat-generating component is mounted on a printed circuit board in this way, the temperature of the printed circuit board will also rise and cause deterioration of circuit components on the printed circuit board. was there.
JP 2005-333315 A

As described above, in the conventional high-stability piezoelectric oscillator, the heat generating component for heating the piezoelectric vibrator in the thermostatic bath is disposed in the vicinity of the printed board supporting the piezoelectric vibrator. There is a problem that the mounted components are excessively heated and deteriorated.
The present invention has been made in view of the above, and surrounds a piezoelectric vibrator mounted on a printed circuit board with a metal cap and attaches a heat generating component for heating to the outer surface of the metal cap separated from the printed circuit board. An object of the present invention is to provide a highly stable piezoelectric oscillator in which a child is concentrated and heated to prevent deterioration of circuit components on a printed circuit board due to heat.

In order to solve the above-described problems, a highly stable piezoelectric oscillator according to the present invention includes a surface-mounted base printed board and a top surface of the base printed board by being supported by conductor pins erected on the upper surface of the base printed board. An upper printed circuit board for mounting piezoelectric vibrators arranged in parallel with a predetermined interval therebetween, a piezoelectric vibrator mounted on the lower surface of the upper printed circuit board, and a lower surface of the upper printed circuit board including the piezoelectric vibrator A metal cap that surrounds the space, a heat-generating component fixed to the lower surface of the metal cap in a non-contact state with the upper surface of the base printed circuit board, an oscillation circuit component mounted on the upper surface of the upper printed circuit board, and the components. And a metal oscillator case surrounding the space on the base printed board.
Since the heat generating component is separated from the upper printed circuit board and attached directly to the lower surface of the metal cap, the temperature of the metal cap and the piezoelectric vibrator can be increased, but the upper printed circuit board is not excessively heated. For this reason, there is no problem that the operating temperature range of the semiconductor constituting the various circuit components mounted on the upper printed circuit board is exceeded or the mounted electronic components are deteriorated by thermal aging.

  In the invention, the heat generating component is a power transistor, and the lead terminal tip is solder-connected to the wiring pattern on the base printed board by bending the lead terminal protruding from the main body of the power transistor. And

According to the present invention, the heat-generating component is a power transistor, and a pedestal print projecting on the base printed board in a state in which a lead terminal protruding from the main body of the power transistor is pulled out substantially parallel to the upper surface of the base printed board. The wiring pattern on the substrate and the lead terminal tip are soldered.
The number of manufacturing steps is reduced by eliminating the need for bending the lead terminals of the power transistors or by manually soldering while temporarily fixing the leading ends of the lead terminals to the surface of the base printed board.

Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 1 is a partial front sectional view showing a configuration of a highly stable crystal oscillator as an example of a highly stable piezoelectric oscillator according to an embodiment of the present invention.
A highly stable crystal oscillator 1 for surface mounting is provided in parallel by conductor pins 5 with a predetermined distance between a surface printed base printed circuit board 2 having a mounting terminal at the bottom and the upper surface of the base printed circuit board 2. The upper printed circuit board 10 for mounting the supported piezoelectric vibrator, the crystal vibrator (piezoelectric vibrator) 20 mounted on the lower surface of the upper printed circuit board 10, and the space on the lower surface of the upper printed board including the crystal vibrator 20 are enclosed. And mounted on the upper surface of the base printed circuit board 2 or the upper printed circuit board 10, respectively, and the heat generating component 40 fixed to the lower surface of the metal cap 30 in a non-contact state with the upper surface of the base printed circuit board 2. Oscillation circuit components 50 and 51, a temperature control element (thermistor) 60 disposed at a suitable position on the outer surface of the metal cap 30, and each component 20, 30, 40, 50, 51, The temperature of the crystal resonator 20 is controlled by controlling the amount of heat generated by the heat generating component 40 by feeding back the temperature detected by the temperature control element 60 and the metal oscillator case 70 surrounding the space on the base printed circuit board 2 including 0. And a control circuit (not shown).
A circuit component that is easily affected by heat, for example, a high-frequency oscillation circuit component 50 is mounted on the upper printed circuit board 10, and a circuit component that is resistant to heat is mounted on the base printed circuit board 2.

The heat generating component 40 is, for example, a power transistor, and includes a transistor main body 41 and three lead terminals 42 protruding from the main body 41. In the present embodiment, with the main body 41 fixed to the lower surface of the metal cap 30 by adhesion or the like, the tip end portion of the lead terminal 42 bent into a crank shape is solder-connected to the wiring pattern on the base printed board 2. Since the main body 41 serving as a heat source is separated from the upper printed circuit board 10, heat from the heat generating component 40 is directly transmitted to the upper printed circuit board 10, and the mounted circuit component 50 may be excessively heated and deteriorated. Absent. That is, since the heat generating component 40 has a structure in which the built-in crystal resonator 20 is heated through the metal cap 30, the upper printed circuit board is prevented from excessively exceeding the temperature of the crystal resonator. Is done. On the other hand, since the heat generating component 40 holds a sufficient space between the upper surface of the base printed circuit board, there is no possibility that the base printed circuit board 2 is excessively heated to adversely affect the mounted components.
Circuit components constituting the control circuit are mounted on, for example, the base printed board 2 and lead terminals extending from the temperature control element 60 are connected to the control circuit.
The metal oscillator case 70 is designed to prevent heat radiation from the metal cap 30 heated by the heat generating component 40 and to prevent electromagnetic adverse effects.

  According to the present invention, when the temperature of the heat generating component 40 during heat generation is T1, the temperature of the upper printed circuit board 10 is T2, the temperature of the metal cap (constant temperature bath) 30 is T3, and the temperature of the crystal resonator 20 is T4, These relationships are T1> T3> T4> T2, and the temperature T2 of the upper printed circuit board 10 is significantly lower than the temperature T4 of the crystal resonator. When the temperature of the crystal unit 20 is maintained at about + 80 ° C., the upper printed circuit board temperature T 2 can be kept at about 50 ° C. For this reason, the malfunction which exceeds the use temperature range of the semiconductor which comprises the various circuit components 50 mounted on the upper printed circuit board 10, or the mounted electronic component deteriorates by heat aging is eliminated.

Next, FIG. 2 is a partial front longitudinal sectional view of a highly stable piezoelectric oscillator according to another embodiment of the present invention.
In the highly stable piezoelectric oscillator 1 according to this embodiment, a power transistor is used as the heat generating component 40, and three lead terminals 42 protruding from the main body 41 of the power transistor 40 are drawn out substantially parallel to the upper surface of the base printed board 2. (Without bending), the wiring pattern on the base printed board 80 protruding from the base printed board 2 and the lead terminal tip are soldered.
In the highly stable piezoelectric oscillator according to the embodiment of FIG. 1, the lead terminal 42 protruding from the main body 41 of the power transistor 40 is bent in a crank shape, but the operation of bending the lead terminal in a crank shape and the tip of the lead terminal The operation of soldering the parts to each other is a troublesome manual operation, which causes an increase in man-hours and causes a decrease in productivity.
In the present embodiment, on the base printed circuit board 80 arranged in advance on the base printed circuit board 2 without processing the lead terminal 42 protruding in the lateral direction from the bottom of the main body 41 of the power transistor 40 fixed to the lower surface of the metal cap 30. Since the tip of the lead terminal is solder-connected, it is possible to prevent a decrease in productivity. In the embodiment shown in FIG. 1, it is necessary to perform solder connection by hand while the bent lead terminal is temporarily fixed on the base printed board. However, according to the present invention, the lead terminal is set on the base board surface. In this state, the connection can be performed by an automatic reflow process.

The pedestal printed circuit board 80 is fixed on the base printed circuit board surface in advance so that the upper surface of the pedestal printed circuit board 80 has a positional relationship that can easily support the lead terminal tip.
Although the crystal oscillator has been described in the above embodiment, the present invention can also be applied to other piezoelectric oscillators using a piezoelectric material other than quartz.

1 is a partial longitudinal sectional front view of a highly stable piezoelectric oscillator according to an embodiment of the present invention. It is a front partial longitudinal cross-sectional view of the highly stable piezoelectric oscillator which concerns on other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Highly stable crystal oscillator, 2 ... Base printed circuit board, 5 ... Conductor pin, 10 ... Upper printed circuit board, 20 ... Crystal oscillator (piezoelectric vibrator), 30 ... Metal cap, 40 ... Heat generating component (power transistor), 40 DESCRIPTION OF SYMBOLS ... Heat-generating component, 41 ... Transistor main body, 42 ... Lead terminal, 50 ... Oscillator circuit component, 60 ... Temperature control element, 70 ... Metal oscillator case, 80 ... Base printed circuit board.

Claims (3)

  Piezoelectric vibrators arranged in parallel with a predetermined distance between a base printed board for surface mounting and a conductive pin erected on the upper face of the base printed board so as to be supported on the upper face of the base printed board An upper printed circuit board for mounting, a piezoelectric vibrator mounted on the lower surface of the upper printed circuit board, a metal cap surrounding the space on the lower surface of the upper printed circuit board including the piezoelectric vibrator, and a non-contact with the upper surface of the base printed circuit board A heat generating component fixed to the lower surface of the metal cap in the state of the above, an oscillation circuit component mounted on the upper surface of the upper printed circuit board, and a metal oscillator case surrounding the space on the base printed circuit board including the components, A highly stable piezoelectric oscillator comprising:   2. The heat generating component is a power transistor, and a lead terminal protruding from a main body of the power transistor is bent to solder-connect the leading end of the lead terminal to a wiring pattern on the base printed board. A highly stable piezoelectric oscillator according to 1.   The heat generating component is a power transistor, and a wiring pattern on a base printed board protruding on the base printed board in a state where a lead terminal protruding from the main body of the power transistor is pulled out substantially parallel to the upper surface of the base printed board. 2. The highly stable piezoelectric oscillator according to claim 1, wherein the lead terminal tip is soldered.

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