JP2549796Y2 - Temperature compensated crystal oscillator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-compensated crystal oscillator which is easy to assemble and can be miniaturized.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional miniaturized temperature-compensated crystal oscillator contains a hermetically sealed crystal oscillator 32, a circuit board 33, and the like inside a container 31. Circuits other than the crystal oscillator 32 of the temperature-compensated crystal oscillation circuit shown in FIG. 4 were formed on both main surfaces of the circuit board 33, respectively.

As shown in FIG. 4, a temperature-compensated crystal oscillation circuit includes a temperature compensation circuit A for adjusting the frequency in accordance with the temperature-frequency characteristics of the crystal oscillator X, and a temperature compensation circuit A in accordance with the output of the crystal oscillator X. And an oscillation circuit B for oscillation and amplification.

The circuit board 33 includes a wiring pattern 34, a variable capacitance element 35, a capacitor C,
Electronic components 36 such as a resistor R, a thermistor element Th, and a transistor Tr are arranged.

[0005] The container 31 is composed of a housing 31a made of metal or ceramic and a lid 31b.
The above-mentioned circuit board 33 and the crystal oscillator 32 connected to the circuit board 33 are arranged, and an external terminal 37 electrically connected to the circuit board 33 is formed at the bottom of the container 31. still,
The predetermined wiring pattern 34 of the circuit board 33 and the external terminal 37 are connected by a lead conductor 38 or the like.

An adjustment hole 39 is formed in the container 31, particularly the lid 31b, so that the variable capacitance element 35 mounted on the circuit board 33 can be variably controlled.

Here, in the temperature-compensated crystal oscillator, after connecting the crystal oscillator 32 to the temperature-compensated crystal oscillation circuit, the resistance R constituting the temperature-compensation circuit A is trimmed in the sound chamber to form a crystal. It was necessary to adjust according to the temperature-frequency characteristic unique to the vibrator 32.

[0008]

2. Description of the Related Art In a temperature compensated crystal oscillator having such a structure, the temperature compensation circuit A and the oscillation circuit B are formed on a single circuit board 33.
When the failure occurs, the circuit board 33 in which the oscillation circuit B that does not require adjustment is formed is discarded, so that the productivity is reduced and the manufacturing cost is increased.

Further, a quartz oscillator 32 hermetically sealed in a cylindrical can case is formed inside the container 31, and the variable capacitance element 35 can be easily variably controlled on the upper surface of the container 31. Due to the formation of the adjustment hole 39 having a diameter of the order of magnitude, there is a limit to miniaturization, for example, the total volume is 0.6 cc. On the other hand, in a portable telephone using such a temperature-compensated crystal oscillator, for example, there is a strict requirement that the crystal oscillator has a height of 3.5 mm or less and a volume of 0.5 cc or less, and satisfies this requirement. I couldn't do that.

Further, in the above-described temperature-compensated crystal oscillator, since the adjustment hole 39 for variable control of the variable capacitance element 35 is formed, the temperature-compensated crystal oscillator is mounted on a mounting circuit board and then cleaned. In addition, there is a problem that the cleaning water enters the inside of the container 31 through the adjustment hole 39, and the wiring pattern 34 is corroded or migrated.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a highly reliable temperature-compensated crystal oscillator which can improve productivity, can be further miniaturized. .

[0012]

The present invention comprises a frame, first and second substrates for closing both openings of the frame, and a main portion of the first substrate on the outside of the frame. A quartz oscillator and a variable capacitance element housed in an airtight container are formed on the surface, a temperature compensation circuit is formed on the main surface inside the frame, and an oscillation is formed on the main surface inside the frame of the second substrate. This is a temperature-compensated crystal oscillator in which a circuit is formed.

[0013]

As described above, according to the present invention, the temperature compensation circuit and the oscillation circuit are formed on different circuit boards, respectively, and the other main surface of the circuit board on which the temperature compensation circuit is formed is provided with a hermetically sealed crystal resonator. Since the temperature compensation circuit can be adjusted in accordance with the inherent frequency-temperature characteristic of the crystal resonator, it can be formed separately from the second circuit board on which the oscillation circuit that does not require adjustment is formed. And the overall manufacturing cost can be reduced.

Further, since the variable capacitance element and the quartz oscillator are arranged on the outer main surface of the first circuit board, the circuit structure on the first and second circuit boards can be formed with high density. Thus, a miniaturized temperature compensated crystal oscillator is achieved.

Further, since the variable capacitance element is arranged on the outer main surface of the first circuit board, the container constituted by the frame and the first and second circuit boards is hermetically sealed. Therefore, there is no intrusion of cleaning water or the like, and the operation reliability of the temperature compensation circuit and the oscillation circuit is greatly improved.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a temperature-compensated crystal oscillator according to the present invention. FIG. 1 is a schematic view showing a cross-sectional structure of a temperature compensated crystal oscillator 1 according to the present invention, and FIG. 2 is an exploded perspective view.

In FIG. 1, a temperature-compensated crystal oscillator 1 comprises:
The frame 2, a first circuit board (hereinafter, referred to as a lid circuit board) 3 for closing one opening of the frame 2, and a second circuit board (hereinafter, referred to as lid circuit board) for closing the other opening of the frame 2 Bottom circuit board 4
The crystal oscillator 5, the variable capacitance element 6, the lid circuit board 3 and the bottom circuit board 4 inside the frame of the lid circuit board 3 disposed on the main surface on the outside of the frame. , And various electronic components 7 and 14 arranged at the same time.

The cover circuit board 3 is made of alumina ceramic,
It is made of glass ceramic or the like, and is made of a single plate or a multilayer substrate. Electrode pads 8 to which the quartz oscillator 5 and the variable capacitance element 6 are bonded are provided on the outer main surface of the lid circuit board 3.
In addition, a predetermined wiring pattern 9 is formed on the inner main surface of the lid circuit board 3 in order to achieve the temperature compensation circuit which is the portion A shown in FIG. The electrode pads 8 and the wiring patterns 9 are formed by a known thick film technique. Note that, in order to achieve a temperature-compensated crystal oscillation circuit, the electrode pads 8 formed with the lid circuit board 3 interposed therebetween and the wiring patterns 9 are electrically connected by via holes 11 formed in the lid circuit board 3. ing. An airtightly sealed crystal unit 5 and a variable capacitance element 6 are solder-bonded on the electrode pads 8 on the outer main surface of the lid circuit board 3.
Further, various electronic components 7 constituting the temperature compensation circuit A are soldered on the wiring pattern 9 on the inner main surface of the lid circuit board 3.

The bottom circuit board 4 is made of alumina ceramic,
It is made of glass ceramic or the like, and is made of a single plate or a multilayer substrate. External terminals 12 are formed on the outer main surface, and predetermined wiring patterns 13 are formed on the inner main surface in order to achieve an oscillation circuit which is a portion B shown in FIG. The external terminals 12 and the predetermined wiring patterns 13
Is conducted through a semicircular end surface conduction through hole 15, a via hole, or the like. Various electronic components 14 constituting the oscillation circuit B are soldered on the wiring pattern 9 on the inner main surface of the bottom circuit board 4.

The frame 2 is made of alumina ceramic or the like, and includes at least various electronic components 7 arranged on the inner main surface of the lid circuit board 3 and various electronic components 7 arranged on the inner main surface of the bottom circuit board 4. It has a height that does not make contact with the component 14. The various electronic components 7 and 14 are arranged on the circuit boards 3 and 4 so as not to contact each other.

The cover circuit board 3 and the bottom circuit board 4 arranged so as to close both openings of the frame 2 are joined by a sealer resin (not shown). Further, it is necessary to electrically connect the lid circuit board 3 and the bottom circuit board 4 with each other. Examples of the conductive means include a conductive wiring pattern 16 formed on the inner surface of the frame 2 and a frame (not shown). Body 2
This can be achieved by a via hole formed inside the substrate, a conductive pin extending from one circuit board to the other circuit board, a conductive paste, or the like.

Next, an assembling process of the temperature compensated crystal oscillator 1 will be described.

First, the lid circuit board 3 on which the electrode pads 8 are formed on the outer main surface and the wiring pattern 9 is formed on the inner main surface, the frame 2 on which the wiring pattern 16 is formed, and the end surface conductive through. The bottom circuit board 4 having the holes 15, the external terminals 12, and the wiring pattern 13 formed on the inner main surface is prepared.

Next, various electronic components 7 are joined by reflow soldering to the wiring patterns 9 of the cover circuit board 3, and the crystal unit 5 and the variable capacitance element 6 are further attached to the electrode pads 8 of the cover circuit board 3. Solder joint. As a result, the temperature compensation circuit A and the crystal unit 5 are formed on the lid circuit board 3.

Next, the temperature compensation circuit A of the lid circuit board 3
Is adjusted based on the natural frequency-temperature characteristics of the bonded crystal unit 5. Specifically, the resistance R constituting the temperature compensation circuit A is formed of a thick film resistor, the temperature is controlled in a constant temperature bath, and the resistance value of the thick film resistor is adjusted by laser trimming or the like. Do.

Next, the wiring pattern 13 of the bottom circuit board 4
Various electronic components 14 are joined by reflow soldering. As a result, the oscillation circuit B including the oscillation unit and the output unit excluding the crystal unit 5 is formed on the bottom circuit board 4. It should be noted that no adjustment or the like is required for the oscillation circuit B,
It is possible to form a large number of bottom circuit boards 4 collectively.

Next, as described above, the temperature compensating circuit A adjusted according to the temperature characteristics of the bonded crystal unit 5
Are arranged and integrated so as to close both openings of the frame body 2 with the lid circuit board 3 having the above and one bottom circuit board 4 manufactured collectively. For this integration, the lid circuit board 3
A sealer resin layer is interposed between the bottom circuit board 4 and the frame 3 at the contact portion. At this time, it is important that the wiring pattern 9 of the lid circuit board 3 and the wiring pattern 13 of the bottom circuit board 4 be completely conductive by the conductive wiring pattern 16 formed on the frame 2.

The following effects can be expected from the temperature compensated crystal oscillator manufactured as described above.

The cover circuit board 3 is mainly provided with a temperature compensation circuit A, and the bottom circuit board 4 is mainly provided with a crystal oscillator 5.
Oscillation circuits B are formed except for the respective circuit boards 3,
4 can be manufactured and adjusted in a separate process, so that even if an adjustment error occurs particularly in the adjustment of the temperature compensation circuit A of the cover circuit board 3, only the cover circuit board 3 can be discarded. Since the temperature-compensated crystal oscillator 1 can be assembled only by combining non-defective products, the manufacturing becomes easy and the manufacturing cost is greatly improved.

A temperature compensation circuit A and an oscillation circuit B other than the crystal unit 5 and the variable capacitance element 6 are hermetically sealed in an interior surrounded by the frame 2, the lid circuit board 3, and the bottom circuit board 4. Therefore, the moisture resistance reliability is improved.

Since the variable capacitance element 6 is exposed to the outside, it is not necessary to form an adjustment hole in the variable control of the variable capacitance element 6 as in the related art, and there is a restriction that a driver is inserted through the adjustment hole. Therefore, the capacity can be easily adjusted.

Since the electronic components 7 and 14 other than the crystal unit 5 and the variable capacitance element 6 can be soldered by reflow soldering, the workability is greatly improved.

Since the crystal unit 5 and the variable capacitance element 6 which are relatively large electronic components are formed outside the lid circuit board 3, the dead space in the frame 2 is reduced.
Furthermore, since the oscillation circuit B and the temperature compensation circuit A other than the crystal unit 5 and the variable capacitance element 6 are formed on the formation surfaces of the cover circuit board 3 and the bottom circuit board 4, respectively, the mounting density of the circuit is improved. , As a whole, for example, the bottom area is 49.0 m
m ² or less, the volume is very small the temperature compensated crystal oscillator of 0.167cc is achieved.

An oscillation circuit B, which must be connected to an external circuit, is formed on the bottom circuit board 4. On the bottom side of the bottom circuit board 4, external terminals 12 such as a ground terminal, an output terminal, and a drive voltage supply terminal are formed. Therefore, the reliability of conduction between the oscillation circuit B and the external terminal 12 is improved.

In the above-described embodiment, the temperature compensation circuit A is mainly formed on the lid circuit board 3, but a part of the oscillation circuit B may be mounted with circuit components. In addition to the oscillation circuit B, circuit components unnecessary for adjusting the temperature compensation circuit A may be mounted on the bottom circuit board 4.

The resistance R of the temperature compensation circuit A shown in FIG.
Was formed of a thick-film resistor, but the other resistors R were also
When the wiring patterns 9 and 13 are formed, the wiring patterns 9 and 13 may be formed of a thick film using a resistor paste.

[0037]

As described above, according to the present invention, the temperature compensation circuit and the oscillation circuit that constitute the temperature compensation type crystal oscillation circuit are formed on different circuit boards, and especially, the outside of the circuit board on which the temperature compensation circuit is formed. Since the crystal oscillator and variable capacitance element are arranged on the main surface of the side, the adjustment of the temperature compensation circuit according to the temperature characteristics of the crystal oscillator can be performed completely separately from the circuit board on which the oscillation circuit is formed. Adjustment of the compensation circuit is facilitated, and a circuit board of the oscillation circuit can be manufactured at a time. As a result, productivity is improved, manufacturing is simplified, and manufacturing cost can be significantly reduced.

Further, since the quartz oscillator and the variable capacitance element occupying a relatively large volume are arranged outside, the portion surrounded by the frame and the circuit board is hermetically sealed. As a result, the adjustment of the variable capacitance element becomes easy, the overall size is extremely reduced, and the temperature compensation circuit and oscillation circuit do not corrode or migrate due to moisture, and the operation is stable for a long time. Temperature compensated crystal oscillator.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a temperature compensated crystal oscillator of the present invention.

FIG. 2 is an exploded perspective view of the temperature compensated crystal oscillator of the present invention.

FIG. 3 is a sectional structural view of a conventional temperature compensated crystal oscillator.

FIG. 4 is a diagram of a temperature-compensated crystal emission circuit.

[Explanation of symbols]

 1 ··· Temperature compensated crystal oscillator 2 ···· Frame 3 ···· Cover circuit board 4 ··· Bottom circuit board 5 ··· Crystal oscillator 6 ···· Variable capacitance element 7, 14 ··· Electronic components A ··· Temperature compensation circuit B ····· Oscillation circuit

Claims (1)

(57) [Scope of request for utility model registration] A first frame for closing both openings of the frame;
A quartz oscillator and a variable capacitance element housed in an airtight container on the main surface of the first substrate on the outside of the frame, and a temperature compensation element on the main surface of the first substrate on the inside of the frame. A temperature-compensated crystal oscillator, wherein a circuit is formed, and an oscillation circuit is formed on a main surface of the second substrate inside the frame.