JPH1168465A - Crystal oscillator and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal oscillator capable of easily and surely joining half cases by sealing to constitute a case of a crystal oscillator. SOLUTION: A crystal oscillator is constituted of a case 120 containing a wiring substrate 116 on which a crystal resonator 110, a chip coil 112, a chip capacitor 114, etc., are mounted. The case 120 is formed by joining halves case 120A and 120B made of brass. A circular welding member 200 made of solder corresponding to an outer peripheral shape of the case 120 is interposed in a joining part between each of the halves 120A and 120B. The halves 120A, 120B are joined and sealed by supplying a sharp pulse current by impressing weak discharge pulse to each of the halves 120A, 120B and melting a low melting point welding member 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal oscillator in which a wiring board on which a crystal oscillator or the like is mounted is housed in a case in a sealed state, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a crystal oscillator has a high frequency stability.
It is widely used in various electronic devices. In recent years, with a demand for miniaturization, the demand for a crystal oscillator (crystal piece) and a circuit element sealed in one case has been increasing.

FIG. 5 is a cross-sectional view showing a configuration example of such a conventional crystal oscillator. This crystal oscillator comprises a crystal oscillator 10, a chip coil 12 and a chip capacitor 14.
The wiring board 16 on which the driving circuit including the above is mounted is housed in a substantially box-shaped case 20. Case 20
Is a pair of upper and lower case halves 2 made of, for example, brass.
0A and 20B are joined together.
The lower case half 20B is formed in a substantially rectangular flat plate shape, and the wiring board 16 is mounted on the upper surface.

[0004] The upper case half 20A is formed in a substantially rectangular parallelepiped container shape that covers the upper surface of the lower case half 20B, and has a flange 22 formed on the outer peripheral edge at the lower end. The lower case half 20B is welded to the lower case half 20B so as to match the upper surface of the outer peripheral edge of the lower case half 20B, and the upper case half 20A and the lower case half 20B are joined in a sealed state. ing. Further, the terminal pins 18 bonded to the wiring board 16 are provided on the lower case half 20B.
Insertion holes (not shown) through which the terminals A and 18B pass are provided. Each of the terminal pins 18A and 18B protrudes below the case 20 through the insertion holes, and the insertion holes are sealed by an insulating material (not shown). Have been.

[0005]

In the crystal oscillator having the above-described structure, a method of joining the upper case half 20A and the lower case half 20B in a sealed state is as follows.
A method is known in which a voltage pulse is applied between the case halves 20A and 20B to melt the joint between the case halves 20A and 20B. This is first
With the case halves 20A and 20B aligned as shown in FIG. 5, a high pressure is applied between the case halves 20A and 20B to compress each other. By applying a large pulse voltage between the case halves 20A and 20B in this state, the joints of the case halves 20A and 20B generate heat due to high resistance and fuse with each other. It joins the bodies 20A and 20B. Incidentally, as such a similar technique, Japanese Patent Application Laid-Open No. 3-272207,
Japanese Patent Laying-Open No. 4-165652 is known.

[0006] However, in this method, since the joining portion of each of the case halves 20A and 20B made of brass is melted,
This part must be heated to a few hundred degrees Celsius and a fairly large pulse voltage must be applied. Specifically, for example, an electrolytic capacitor is charged with a voltage of about 310 V, and this is discharged instantaneously, so that each case half 20A,
A steep pulse voltage is applied to 0B. As a result, a welding current of about 33 KA instantaneously flows through each case half 20A, 20B. For this reason, case 20
The magnetic field generated therein increases in proportion to the current value. As a result, there is a problem that the inductance of the internal coil 12 changes and the characteristics of the final product change.

As another method, each case half 20
While there is a method in which the joints are manually soldered with a soldering iron while the A and 20B are aligned as shown in FIG. 5, in this method, in particular, plating is applied to each of the case halves 20A and 20B. Therefore, it is difficult to attach the solder, so that the operation is extremely complicated, and a large number of steps are required for the soldering, and the soldering is likely to be uneven, and it is difficult to obtain a completely airtight state.

SUMMARY OF THE INVENTION An object of the present invention is to provide a crystal oscillator and a method of manufacturing the crystal oscillator, which can easily and reliably join the case halves constituting the case of the crystal oscillator in a sealed state.

[0009]

In order to achieve the above object, a crystal oscillator according to the present invention has a case formed by joining a pair of case halves each made of a conductive material at a joint portion of each other. A wiring board mounted with a quartz oscillator and its driving circuit and housed in the case in a sealed state, and joined to each of the case halves in an annular shape corresponding to a joint of the case halves. A welding member interposed between the portions and having a significantly lower melting point with respect to the conductive material of each of the case halves; and a welding member for joining the case halves together. The case is heated and melted by a weak high-frequency voltage applied between the case halves, and the joints of the case halves are joined in a sealed state.

Further, according to the method of manufacturing a crystal oscillator according to the present invention, a quartz oscillator and a driving circuit therefor are provided in a case formed by joining a pair of case halves each made of a conductive material to each other at a joint. In a method of manufacturing a crystal oscillator that houses a wiring board in which a wiring board is mounted in a sealed state, a conductive material having a significantly lower melting point with respect to the conductive material of each of the case halves between the joints of the case halves. It is made of a material, and an annular welding member corresponding to the joint of the case halves is interposed therebetween, and a given pressing force is applied between the case halves. The welding members are heated and melted by applying a weak high-frequency voltage between them to join the case halves together.

In the above-described crystal oscillator of the present invention, the wiring board on which the crystal oscillator and its drive circuit are mounted is housed in a sealed state in a case composed of a pair of case halves joined via a welding member. I have. Further, the welding member having a lower melting point than the case halves interposed between the joints of the case halves can be formed at a relatively low temperature by the weak high-frequency voltage applied between the case halves. It melts easily and uniformly over the entire joint of the body and is welded to the joint of each case half to join them together in a good sealed state.
Therefore, the inside of the case is placed in a good airtight state, and since the case halves are joined without flowing a large current,
A crystal oscillator having stable characteristics can be provided without affecting the inductance of the internal coil. In the above-described method of manufacturing a crystal oscillator according to the present invention, a welding member having a lower melting point than the case halves is interposed between the joints of the case halves. Then, a constant pressing force is applied between the case halves, and the welding member is pressed and held by the joint of the case halves. Next, in this state, a weak high-frequency voltage such as a discharge pulse from a capacitor or the like is applied between the case halves. As a result, heat is generated due to high resistance in the gap between the joint of each case half and the welding member, and the welding member is easily and uniformly melted over the entire periphery of the joint of the case half at a relatively low temperature. I do. As a result, the joining portion of each case half and the melted welding member are welded, and each case half can be joined in a good sealed state. Therefore, the inside of the case is placed in a good airtight state, and the case halves are joined without flowing a large current, so that a crystal oscillator having stable characteristics can be provided without affecting the inductance of the internal coil.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a crystal oscillator and a method of manufacturing the same according to the present invention will be described. FIG.
1 is an exploded perspective view showing an example of a crystal oscillator according to the present invention. 2 is an external perspective view showing a state after assembling the crystal oscillator shown in FIG. 1, and FIG. 3 is a sectional view showing an internal structure of the crystal oscillator shown in FIG. 1 at the time of assembly. In this crystal oscillator, a wiring board 116 on which a crystal oscillator 110 and a driving circuit including a chip coil 112 and a chip capacitor 114 are mounted is housed in a substantially box-shaped case 120. The case 120 includes a pair of upper and lower case halves 120 formed of, for example, brass.
A, 120B are formed by joining each other.
The lower case half 120B is formed in a substantially rectangular flat plate shape, and has a wiring board 116 mounted on its upper surface.

The upper case half 120A is formed in a substantially rectangular parallelepiped container shape which covers the upper surface of the lower case half 120B, and has a flange 122 formed on the outer peripheral edge at the lower end. The lower case half 1A and the upper case half 120A are joined to each other so that the lower surface is aligned with the upper surface of the outer peripheral edge 124 of the lower case half 120B.
20B is joined in a sealed state. That is, in this example, the flange portion 122 of the upper case half 120A and the outer peripheral edge 124 of the lower case half 120B are formed as joints for joining the case halves 120A and 120B. I have.

The lower case half 120B has terminal pins 118A to 118C joined to the wiring board 116.
An insertion hole (not shown) through which the terminal pins 118A to 118C pass through the case 12 is provided.
0, and the insertion hole is sealed with an insulating material (not shown).

The flange 122 of the upper case half 120A and the outer peripheral edge 12 of the lower case half 120B
4, a welding member 200 made of solder (a mixture of lead and tin approximately half each) is interposed. The welding member 200 is provided on the upper case half 120A.
Is formed in a substantially rectangular ring shape in accordance with the shape of the flange portion 122 and the outer peripheral edge portion 124 of the lower case half 120B, and the lower surface of the flange portion 122 and the outer peripheral edge portion 124 are formed.
Is welded over the entire periphery thereof, and the case halves 120A and 120B are joined in a sealed state. The welding member 200 made of solder has a melting point of about 100 ° C., and is much lower than the brass forming the case 120. Note that, in detail, the welding member 20
0 is the case half 120 so that it does not leak out during melting.
A is slightly smaller than the flange 122 of A and the outer peripheral edge 124 of the lower case half 120B.

In the crystal oscillator configured as described above, the case halves 120A and 120B are joined together with the welding member 200 interposed therebetween, and a predetermined pressure is applied between the case halves 120A and 120B to perform welding. By applying a weak discharge pulse between the case halves 120A and 120B while the member 200 is pressed and held, the welding member 200 is heated and melted, and the case halves 120A and 120B are joined. is there.

Next, a method of manufacturing the above-described crystal oscillator will be described. FIG. 4 is an explanatory diagram showing an outline of the joining operation of the case halves 120A and 120B of the crystal oscillator in this example. As shown in FIG. 4, first, a joint between the case halves 120A and 120B, that is, the case half 1
Lower surface of flange portion 122 of 20A and case half 120B
The case halves 120 </ b> A and 120 </ b> B are overlapped with the welding member 200 interposed between the upper surface of the outer peripheral edge 124 of the case.

Then, each case half 120A, 120B
Between the case halves 120 by applying a constant pressing force P between them.
The welding member 200 is pressed and held by the joints A and 120B. Here, the pressing force P is, for example, per 1 cm ² ,
It is about 4.5 kg. Next, both ends of a series circuit of an electrolytic capacitor 300 and an on / off switch 310 for obtaining a discharge pulse are connected to the case halves 120A and 120B.
Then, while the open / close switch 310 is open, the electrolytic capacitor 300 is charged. Here, the voltage v ₀ of about 30 V is charged in the electrolytic capacitor 300.

Thereafter, by closing the open / close switch 310, a discharge loop is formed between the electrolytic capacitor 300 and the case 120, and the voltage charged in the electrolytic capacitor 300 becomes an instantaneous discharge pulse, and each case is half-discharged. Body 1
An instantaneous welding current applied between 20A and 120B flows through each case half 120A and 120B and the welding member 200.

As a result, each case half 120A, 120
Due to the large resistance value of the gap between the joining portion B and the welding member 200, this portion is heated to a temperature of a hundred and several tens of degrees Celsius. Thereby, the welding member 200 is melted, and each case half 12
It is crushed by the pressing force P applied to 0A and 120B, and the joints of the case halves 120A and 120B are welded in a sealed state over the entire circumference. At this time, the welding current due to the discharge pulse is about 1 KA, and is supplied in a steep pulse waveform, so that the instantaneous frequency is close to infinity.

As described above, the welding member 20 made of solder
0 can be melted at a relatively low temperature, so that each case half 120A, 120B can be melted by a welding current of about one-tenth the size of a conventional case in which the case half bodies 120A and 120B are directly melted and joined. The bodies 120A, 120B can be joined in a good sealed state. Since the case halves 120A and 120B are joined without flowing a large current, a crystal oscillator having stable characteristics can be provided without affecting the inductance of the internal coil.

In the above example, the welding member 200 made of solder is used. However, the present invention is not limited to this, and other materials may be used as long as the material has a low melting point. Further, in the above example, the example of the welding member 200 formed in a substantially rectangular annular shape has been described, but this shape is appropriately set according to the outer peripheral shape of the case, that is, the shape of the joint portion of the case half. Things. Further, a plurality of annular welding members may be combined and interposed at the joint of the case half, or a plurality of semi-annular welding members may be combined to form an annular welding member, which is interposed at the joint of the case half. Such a configuration is also included in the scope of the present invention. That is, the welding member for joining the case halves can be appropriately selected according to the characteristics and structure of the crystal oscillator.

[0023]

As described above, in the crystal oscillator of the present invention, a welding member having a low melting point interposed between the joints of the case halves constituting the case is applied between the case halves. It is heated and melted by a weak high-frequency voltage, and the case halves are joined in close contact. For this reason, welding can be performed by a weak high-frequency voltage by a welding member that can be heated and melted at a relatively low temperature, so that the case halves can be uniformly joined over the entire periphery of the joint of the case halves,
Since both can be joined in a good sealed state and the case halves can be joined without flowing a large current, a crystal oscillator having stable characteristics can be provided without affecting the inductance of the internal coil. Further, in the method of manufacturing a crystal oscillator according to the present invention, a welding member having a low melting point is interposed between the joints of the case halves constituting the case, and a constant pressing force is applied between the case halves. Then, by applying a weak high-frequency voltage between each case half,
The welding members were heated and melted to join the case halves together. For this reason, the welding member can be heated and melted at a relatively low temperature without applying a large voltage at the time of joining the case halves, so that the case halves can be joined uniformly over the entire periphery of the joint portion of the case halves. Since the joining can be performed in a good sealed state and the case halves can be joined without flowing a large current, a crystal oscillator having stable characteristics can be provided without affecting the inductance of the internal coil.
In addition, the work becomes simpler and the airtightness of the case can be reliably obtained as compared with the case where soldering is performed manually.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of a crystal oscillator according to the present invention.

FIG. 2 is a perspective view showing an appearance of the crystal oscillator shown in FIG.

FIG. 3 is a sectional view showing an internal structure of the crystal oscillator shown in FIG.

FIG. 4 is an explanatory view showing an outline of a joining operation of the case halves of the crystal oscillator shown in FIG. 1;

FIG. 5 is a sectional view showing an internal structure of a conventional crystal oscillator.

[Explanation of symbols]

110: crystal oscillator, 112: chip coil, 11
4 ... Chip capacitor, 116 ... Wiring board, 118
A, 118B ... terminal pin, 120 ... case, 120
A, 120B ... half case, 122 ... flange part,
124 ... outer peripheral edge, 200 ... welding member, 300 ...
Electrolytic capacitor, 310 ... open / close switch.

Claims (14)

[Claims] 1. A case formed by joining a pair of case halves each made of a conductive material at a joint portion thereof, a quartz oscillator and a drive circuit thereof are mounted, and the case is sealed in the case. The wiring board accommodated in the state, and is formed in an annular shape corresponding to the joint of the case halves and is interposed between the joints of the case halves, and the conductive material of the case halves. A welding member made of a conductive material having a significantly lower melting point, wherein the welding member is interposed between the joints of the case halves and applied between the case halves. A crystal oscillator, wherein the crystal oscillator is heated and melted by a weak high-frequency voltage, and the joining portions of the respective case halves are joined in a sealed state. 2. The crystal oscillator according to claim 1, wherein the weak high-frequency voltage is a steep pulse voltage caused by discharge. 3. The crystal oscillator according to claim 1, wherein the conductive material of the welding member is a low melting point alloy. 4. The crystal oscillator according to claim 3, wherein said low melting point alloy is solder. 5. The crystal oscillator according to claim 1, wherein the conductive material of each case half is brass. 6. The case according to claim 1, wherein a flange portion is formed at a joint portion of at least one of the case halves, and the welding member is welded to the flange portion. Crystal oscillator according to the item. 7. One of the case halves has an insertion hole for passing a terminal pin protruding from the wiring board, and the terminal pin projects outside the case through the insertion hole. 7. The crystal oscillator according to claim 1, wherein said insertion hole is sealed with an insulating material. 8. A lower case half of each of said case halves is formed in a substantially plate shape, and said wiring board is mounted thereon.
The crystal oscillator according to claim 1, wherein the upper case half is formed in a container shape that covers an upper surface of the lower case half. 9. A wiring board on which a quartz oscillator and its drive circuit are mounted is sealed in a case formed by joining a pair of case halves each made of a conductive material at a joint portion of each other. In the method for manufacturing a crystal oscillator to be housed, between the joints of the respective case halves, a conductive material having a significantly lower melting point than the conductive material of the respective case halves, A weak high-frequency voltage is applied between the case halves in a state where a fixed pressing force is applied between the case halves with a ring-shaped welding member corresponding to the joining portion interposed therebetween. Thus, the welding members are heated and melted to join the case halves together, thereby producing a crystal oscillator. 10. The method according to claim 9, wherein the weak high-frequency voltage is a steep pulse voltage caused by discharge. 11. Connecting a series circuit of a capacitor and an open / close switch between the case halves, charging the capacitor to a predetermined voltage with the open / close switch open, and then closing the open / close switch. 11. The method according to claim 10, wherein the capacitor is discharged to apply the pulse voltage between the case halves. 12. The method according to claim 9, wherein the conductive material of the welding member is a low melting point alloy. 13. The low melting point alloy is solder.
3. The method for manufacturing the crystal oscillator according to 2. 14. The method according to claim 9, wherein the conductive material of each case half is brass.