JPH1127085A - Surface mount crystal vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the low exciting level characteristic, the aging characteristic, etc., of a surface mount crystal vibrator. SOLUTION: An inside cover 23 is prepared to prevent the high temperature solder 22 formed at an entire part excluding a bonding part 13 of a container cover part 2 to be bonded to a container main body part 3 from being exposed in the part 3. Thus, the minute balls of the solder 22 never stick to the inner wall of the part 3 and a crystal piece 14 when the part 3 is bonded to the part 2. The cover 23 is projecting over the part 13 and the part 3 has a recessed shape. In such a constitution, the minute balls of the solder 22 never stick to the inner wall of the part 3 and the piece 14 from the part 13 when both parts 2 and 3 are bonded together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type crystal unit.

[0002]

2. Description of the Related Art Quartz resonators have been widely used as frequency control elements for various electronic devices. In recent years, as electronic devices have become smaller and higher in density, surface mount type crystal units that can be mounted on, for example, the surface of a printed circuit board have been developed.

[0003] Generally, a crystal oscillator is, for example, 3 × 10
^It is necessary to provide a crystal blank in a container sealed at an air density of about ^-9 (Pa · m ³ / sec). For example, when the container of a surface mount type crystal unit is hermetically sealed, a seam welding method is used. Used.

FIG. 5 is an assembly perspective view for explaining a container structure of a surface mount type crystal unit capable of hermetically sealing the inside of the container by a seam welding method, and FIG. 6 is a front view shown in FIG. FIG. 4 is a cross-sectional view of the mounted crystal resonator viewed from the direction indicated by arrows BB ′. As shown in FIGS. 5 and 6, the container of the surface-mount type crystal unit includes a container body 51 and a container lid 52. The container main body 51 is formed of, for example, a ceramic having a box-shaped (concave) shape, and has an electrode lead-out projection 51 connected to the electrode of the crystal blank 54 and the crystal blank 54 mounted therein. A projection 53 is provided for placement.

[0005] A joining member 55 for joining the container body 51 and the container lid 52 is provided at a peripheral edge of the container body 51. As the joining member 55, as shown in FIG. 6, for example, a member obtained by applying a nickel (Ni) plating 57 to a Kovar 56 and further applying a gold plating 58 is used. Further, as the container lid 52 to be joined to the peripheral portion of the container main body 51, for example, a Kovar 59 obtained by applying a nickel plating 60 to the Kovar 59 is used.

When the container body 51 and the container lid 52 having such a structure are welded by a seam welding method,
After the container main body part 51 and the container lid part 52 are overlapped, the container body part 51 is passed between the roller contacts of the welder which is turned on.
As a result, the container body 51 and the container lid 52 are energized, the joining member 55 provided on the joint surface of the container body 51 is welded, and the container body 51 and the container lid 52 are welded.
Are bonded, and the inside of the container provided with the crystal piece 54 is sealed in an airtight state.

However, since the container used for the seam welding method needs to use the Kovar 56 which has been subjected to nickel plating 57 and gold plating 58 as the joining member 55, there has been a problem that the cost is extremely high.

Further, in recent years, with further miniaturization and higher densities of various electronic devices, there has been a demand for further miniaturized shapes of quartz oscillators used in various electronic devices. However, when the shape of the surface mount type crystal unit is further reduced, it has been difficult to join the container body 51 and the container lid 52 by the seam welding method as described above.

Therefore, as a method for hermetic sealing when the shape of the surface-mount type crystal unit is further reduced, a solder melting method or a gold-tin melting method is used.

FIG. 7 is a cross-sectional view for explaining a container structure of a surface mount type crystal unit used for a solder melting method, for example. The container of the surface-mount type crystal unit shown in FIG. 7 includes a container body 70 and a container lid 72. The container body 70 is formed of a ceramic having a box shape (concave shape) similarly to the container body 51 shown in FIGS. 5 and 6 described above, and is connected to an electrode of the crystal piece 54 inside. A projection 51 for extracting the electrode and a projection 53 for mounting the crystal blank 54 are provided.

A container lid 7 is provided around the periphery of the container body 70.
In order to join the two, a joint portion 71 is formed by, for example, applying nickel plating to a metallized surface. The metallization may be performed, for example, by sintering a green sheet (for example, by suspending aluminum powder in a solvent, a plasticizer, or the like) used to produce a conductor pattern on the ceramic by screen printing before firing the ceramic forming the container body 70. This is generated when the ceramic is fired by applying tungsten W to a sheet that has been dried in the form of a sheet. The container lid 72 joined to the container main body 70 is made of, for example, a clad material in which Kovar 73 and high-temperature solder 74 are adhered by rolling.

When the container main body 70 and the container lid 72 having such a structure are joined together, the container main body 70 and the container lid 72 are passed through a reflow furnace in a state where the container main body 70 and the container lid 72 are overlapped. The high-temperature solder 74 of the container lid 72 is melted, the joining portion 71 of the container body 70 and the container lid 72 are joined, and the inside of the container provided with the crystal blank 54 is hermetically sealed. .

Although not shown, the container structure of the surface mount type crystal unit used in the gold-tin melting method has a container lid 72 used in the above-described solder melting method.
3 and a clad material bonded by rolling a gold-tin alloy.

[0014]

However, when the container of the surface mount type crystal unit is formed by the above-mentioned solder melting method (gold-tin melting method), the high-temperature soldering of the container lid 72 in the reflow furnace is performed. When the metal 74 is melted, the high-temperature solder (gold-tin alloy) 74 or the high-temperature solder (gold-tin alloy)
Four microspheres 75 were generated, and these microspheres 75 sometimes adhered to the inner wall of the container body 70 or the crystal piece 54.

The microspheres 75 of high-temperature solder (gold-tin alloy) adhering to the inner wall of the container body 70 and the crystal piece 54 are
When the voltage applied to the quartz oscillator drops,
However, there is a problem in that a low excitation level characteristic failure in which the series resonance resistance becomes extremely large, and an aging characteristic failure in which the impedance and the frequency fluctuate with the passage of time.

For this reason, conventionally, the temperature condition of the reflow furnace, that is, the so-called reflow furnace temperature profile when the container body 70 and the container lid 72 are joined to each other, is optimized by changing the container lid 7.
The high-temperature solder (gold-tin alloy) microspheres 75 generated from the second high-temperature solder (gold-tin alloy) 74 are minimized.
It was very difficult to completely suppress.

[0017]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a container lid portion formed by a lid member in which an outer lid member and a joining member are adhered by rolling is provided. By bonding to the container body, the surface mount type crystal unit in which the crystal body is provided with the crystal piece sealed in an airtight state, except for the bonding surface of the container lid to be bonded to the container body. The inner lid formed so as not to expose the joining member formed in the container main body is provided.

The joining member is made of high-temperature solder or gold-tin alloy. In addition, the inner lid has a shape protruding from a joint surface of the container lid that is joined to the container main body, and the container main body has a concave shape.

According to the present invention, the inner lid is formed so that the joining member formed on the surface other than the joint surface of the container lid joined to the container main body is not exposed in the container main body. Therefore, when the container body and the container lid are joined, it is possible to prevent the microspheres of the melt of the joining member scattered from the joining member formed other than the joint from adhering to the inner wall of the container body or the crystal piece. Can be.

Further, the inner lid has a shape protruding from the joint surface of the container lid to be joined to the container main body, and the container main body has a concave shape so that the container main body and the container lid are joined. At this time, it is possible to prevent the microspheres of the melt of the joining member, which are sometimes scattered from the joining portion, from adhering to the inner wall or the crystal piece of the container body.

[0021]

Embodiments of the present invention will be described below. FIG. 1 is an external perspective view showing a container structure of a surface mount type crystal unit as a first embodiment of the present invention, and FIG. 2 is a perspective view of the container of the surface mount type crystal unit shown in FIG. FIG. 2 shows a perspective view before assembling.

The surface mount type crystal resonator shown in FIGS. 1 and 2 is composed of a container main body 3 formed of, for example, a ceramic on a flat plate, and a container lid 2 formed as shown in the figure. I have. Inside the container main body 3, there are electrode protrusions 12a, 12a connected to the electrodes of the crystal blank 14.
b and a convex portion 15 for mounting the crystal blank 14 are formed. The protruding portion 12 a for electrode extraction is connected to the upper surface electrode 14 a
The electrode lead-out protrusion 12 b is connected to a back electrode (not shown) of the crystal blank 14 by a conductive adhesive member 16.

At the periphery of the container body 3 to which the container lid 2 is joined, there is formed a joint 13 formed by applying a nickel plating to a metallized surface, for example. Although not shown, on the back surface of the container body 3,
An electrode terminal and a ground terminal connected to the electrode lead-out protrusions 12a and 12b are provided.

FIG. 3A is a cross-sectional view of the surface-mount type crystal resonator shown in FIG. 2 as viewed from the direction indicated by arrows AA ′, and FIG. 3B is a view shown in FIG. FIG. 2 is a cross-sectional view of the surface-mount type crystal resonator as viewed from the direction of arrows AA ′.

As shown in FIGS. 3A and 3B, the container lid 2 of the surface-mount type crystal unit is composed of an outer lid 21, a high-temperature solder 22 serving as a joining member, and an inner lid 23. It is configured. The outer lid 21 and the high-temperature solder 22 are formed, for example, of a clad material in which Kovar, which is an outer lid member, and high-temperature solder, which is a joining member, are adhered by rolling.

The material of the inner lid 23 provided inside the high-temperature solder 22 is, for example, nickel-plated copper, and the shape is joined to the joint 13 of the container body 3. It is shaped so as to cover portions other than the joint surface of the container lid 2.

When the container main body 3 and the container lid 2 having such a structure are joined together, the container main body 3 and the container lid 2 are passed through the reflow furnace in a state where the container main body 3 and the container lid 2 are overlapped. The high-temperature solder 22 of the container lid 2 is melted, and the joining portion 13 of the container main body 3 and the container lid 2 are joined together.
The inside of the container provided with 4 is hermetically sealed.

In this case, when the high-temperature solder 22 of the container lid 2 is melted in the reflow furnace and the container lid 2 is joined to the joint 13 of the container main body 3, the high-temperature solder 22 serving as a joining member is formed. Even if microspheres are generated from the solder 22, the microspheres of the high-temperature solder 22 are covered with the inner lid 23 so as not to be exposed to the interior of the container except for the joint surface of the container lid 2, so that the microspheres may not be exposed. Can be prevented. Therefore,
It is possible to prevent the occurrence of a low excitation level characteristic defect or an aging characteristic defect caused by the microspheres of the high-temperature solder 22 adhering to the inner wall of the container or the crystal piece 14.

Next, FIG. 4 is a cross-sectional view of a surface-mount type crystal unit according to a second embodiment of the present invention. Note that the external view of the surface mount type crystal resonator according to the second embodiment is substantially the same as that of FIGS. 1 and 2 and thus is omitted, and the cross-sectional view shown in FIG. FIG. 2 is a diagram of the surface-mounted crystal resonator according to the embodiment as viewed from the direction indicated by arrows AA ′ in FIG. 2.

The container body 31 of the surface-mount type crystal unit shown in FIGS. 4A and 4B is formed of, for example, a ceramic having a box-shaped (concave) shape. The projections 12a and 12b for extracting the electrodes connected to the electrodes of the crystal blank 14 and the projections 15 for mounting the crystal blank 14 are formed in the same manner as in FIG. Further, a joining portion 13 formed by applying nickel plating to a metalized surface, for example, is formed on a peripheral portion of the container body 31.

The outer lid 21 and the high-temperature solder 22 are formed, for example, of a clad material in which Kovar and high-temperature solder are applied by rolling, as in FIG. The inner lid 24 is formed so as to cover a part other than the joint surface of the container lid part 4 joined to the joint part 13 of the container body part 3. However, this inner lid 24 is the inner lid 2 shown in FIG.
3 has a shape that protrudes from the joint surface of the container lid 4 that is joined to the container body 31. The material of the inner cover 24 is, for example, copper plated with nickel.

When the container body 31 and the container lid 4 having such a structure are joined together, the container body 31 and the container lid 4 are passed through the reflow furnace with the container body 31 and the container lid 4 overlapped. The high-temperature solder 22 of the lid 4 is melted, and the joint 13 of the container body 31 and the container lid 4 are joined.

In this case, since the inner lid 24 is formed so as to protrude from the joint surface between the container body 31 and the container lid 4, the high-temperature solder 22 of the container lid 4 is melted in the reflow furnace. When the joint surface of the container lid 4 is joined to the joint 13 of the container body 31, the joint 13 is also covered by the inner lid 24. It becomes possible to prevent the microspheres from adhering to the inner wall of the container and the crystal piece 14. Therefore, the high-temperature solder 22
Can be almost completely prevented from adhering to the inner wall of the container and the crystal piece 14, so that the low excitation level characteristics, the aging characteristics, and the like of the crystal resonator can be significantly improved.

Further, since the inner lid 24 is formed so as to protrude from the joint surface of the container lid 4, the container body 31
There is also an advantage that the positioning of the container lid 4 can be easily performed when the container lid 4 is overlapped with the container.

In this embodiment, the case where a high-temperature solder having a melting point higher than that of ordinary solder is used as the joining member has been described. However, it is naturally possible to use a gold-tin alloy or the like. Ordinary solder having a lower melting point than high-temperature solder may be used. In addition, the material of the inner lids 23 and 24 has been described as being made of copper plated with nickel, but is not particularly limited.

[0036]

As described above, the surface mount type crystal unit according to the present invention is configured such that the joining members formed at portions other than the joining portion of the container lid joined to the container body are not exposed in the container body. Since the inner lid is provided, the microspheres of the joining member scattered from the joining members other than the joining portion when the container body and the container lid are joined do not adhere to the inner wall or the crystal piece of the container body. , Low excitation level characteristics, aging characteristics and the like can be improved.

Further, if the inner lid is formed to have a shape protruding from the joint surface of the container lid portion to be joined to the container main body, and if the container main body is formed to have a concave shape, the minuteness of the joining member scattered into the container main body is reduced. Since the ball can be almost completely prevented, the low excitation level characteristic, the aging characteristic, and the like can be greatly improved. Furthermore, when the container body and the container lid are overlapped, the positioning of the container lid can be easily performed, which also has the effect of improving productivity.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a container structure of a surface mount type crystal unit according to a first embodiment of the present invention.

FIG. 2 is a perspective view before assembling showing a container structure of the surface mount type crystal unit according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of the surface-mount type crystal unit according to the first embodiment of the present invention, as viewed from the direction of arrows AA ′ shown in FIG.

FIG. 4 is a cross-sectional view of a surface-mount type crystal unit according to a second embodiment of the present invention, as viewed from the direction of arrows AA ′ shown in FIG.

FIG. 5 is an assembly perspective view showing a container structure of a surface mount type crystal unit used in a conventional seam welding method.

FIG. 6 is a cross-sectional view of the container structure of the surface mount type crystal unit used in the conventional seam welding method, as viewed from the direction indicated by arrows BB ′ shown in FIG.

7 is a cross-sectional view of the container structure of the surface mount type crystal unit used in the conventional solder melting method, as viewed from the direction of arrows BB 'shown in FIG.

FIG. 8 is a diagram schematically showing a state of scattering of solder microspheres scattered in a container of a conventional surface mount type crystal unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Surface mount type crystal oscillator, 2 4 Container lid part, 3 3
DESCRIPTION OF SYMBOLS 1 Container main body part, 12a 12b Protruding part for electrode extraction, 1
Reference Signs List 3 bonding part, 14 crystal piece, 15 convex part, 16 adhesive member 21 outer lid, 22 high-temperature solder, 23 24 inner lid

Claims (4)

[Claims] A container lid formed by a cover member in which an outer lid member and a joining member are adhered by rolling is joined to the container body to keep the container body provided with the crystal blank in an airtight state. In the sealed surface mount type crystal unit, an inner portion formed so that the joining member formed other than the joining surface of the container lid portion joined to the container body portion is not exposed in the container body portion. A surface mount type crystal unit characterized by providing a lid. 2. The surface mount type crystal unit according to claim 1, wherein said joining member is made of high-temperature solder. 3. The surface mount type crystal unit according to claim 1, wherein said joining member is made of a gold-tin alloy. 4. The container according to claim 1, wherein the inner lid has a shape protruding from a joint surface of the container lid joined to the container body.
2. The surface-mounted crystal resonator according to claim 1, wherein the container body has a concave shape.