JP2002198767A - Container for housing piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that of a crack is produced on bottom plate of an insulation base because stress is concentrated onto the bottom plate due to a difference in thermal expansion rate between a metal-made cover and the insulation base when the cover is welded to the base. SOLUTION: In a container for housing a piezoelectric vibrator consisting of an insulation base 1 where a frame 1b is joined with an upper face of a bottom plate 1a and a recessed part 4 of nearly a rectangle shape to house the piezoelectric vibrator 3 is placed to the upper face, a step difference section 5 that is formed on a bottom face of the recessed part 4 at its inner end and to the upper face of which an end of the piezoelectric vibrator 3 is fitted, a frame shaped metalized metallic layer 9 coated on the upper face of the frame 1b, a metallic frame 10 joined with the frame shaped metalized metallic layer 9, and a metal-made cover 2 welded to the metallic frame 10 and covering the recessed part 4, a bottom face ceramic coat layer 6 extended between the bottom plate 1a and the step difference section 5 is formed to the bottom face of the recessed part 4 in the vicinity of at least near the center of the lower side of the step difference section 5. Even when a thermal stress takes place in the case of welding the metal made cover 2 to the frame 10, no crack is caused to the bottom plate 1a of the insulation base 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container for accommodating a piezoelectric vibrator such as a quartz vibrator or a ceramic vibrator.

[0002]

2. Description of the Related Art Conventionally, a container for accommodating a piezoelectric vibrator, such as a quartz vibrator or a ceramic vibrator, has a bottom plate 21 as shown in a sectional view of FIG. 7 and a perspective view of FIG.
a frame 21b is joined to the outer peripheral portion of the upper surface of the bottom plate 21a, and a substantially rectangular recess 23 for accommodating the piezoelectric vibrator 22 on the upper surface of the bottom plate 21a
Is provided on the bottom surface of the inner end of the concave portion 23, the step 26 to which the end of the piezoelectric vibrator 22 is attached on the upper surface, and the upper surface of the frame 21b. The metallized metal layer 24 in the form of a frame, the metal frame 25 joined to the metallized metal layer 24, and the recess 23 welded to the metal frame 25.
And a metal lid 27 that closes the cover. FIG.
5 shows a state in which the piezoelectric vibrator 22 and the metal lid 27 have been removed.

An end of the piezoelectric vibrator 22 is attached and fixed to the upper surface of the step 26 via an adhesive made of a brazing material, a conductive resin, or the like, and an iron-nickel-cobalt alloy or A metal lid 27 made of an iron-nickel alloy or the like is welded by a seam welding method or the like to form an insulating base 21 and a metal frame.
The piezoelectric vibrator 22 is hermetically accommodated in a container including the metal cover 25 and the metal lid 27, thereby providing a piezoelectric device as a final product.

[0004]

However, in the conventional container for accommodating a piezoelectric vibrator, the piezoelectric vibrator 22 such as a crystal vibrator or a ceramic vibrator is housed inside the concave portion 23 of the insulating base 21, and then the metal vibrator is filled with metal. When a metal lid 27 is welded to the frame 25 by a seam welding method or the like to produce a piezoelectric device, only the metal lid 27 expands greatly due to heat during welding and contracts greatly when cooled. On the other hand, the insulating base 21 made of ceramic has a small coefficient of thermal expansion as compared with the metal lid 27, so that it hardly changes. Therefore, when the metal lid 27 contracts significantly during cooling, stress is generated in the insulating base 21 to which the metal lid 27 is welded.

The stress may concentrate on the bottom surface of the concave portion 23, specifically on the upper surface portion of the bottom plate 21a in contact with the vicinity of the center of the lower side of the step portion 26, and cracks may be generated on the bottom plate 21a. Therefore, there is a problem that the hermetic sealing of the container is broken and the piezoelectric vibrator 22 housed inside the container cannot be normally and stably operated for a long period of time.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to prevent the occurrence of cracks in a bottom plate constituting a bottom surface of a concave portion of an insulating substrate and hermetically seal a container. It is an object of the present invention to provide a container for storing a piezoelectric vibrator in which the reliability of the piezoelectric vibrator is high and the piezoelectric vibrator contained in the container can be operated normally and stably for a long period of time.

[0007]

In the container for accommodating a piezoelectric vibrator according to the present invention, a frame is joined to an upper surface of a bottom plate, and a substantially rectangular recess for accommodating the piezoelectric vibrator is provided on the upper surface. An insulating base, a step formed on the bottom surface of the inner end of the recess, on which the end of the piezoelectric vibrator is attached, and a frame-shaped metallized metal attached on the top of the frame Layer, a metal frame joined to the frame-shaped metallized metal layer, and a metal container closing the recess to be welded to the metal frame. A bottom surface ceramic coating layer extending between the bottom plate and the step portion is formed at least near the center of the lower side of the step portion.

According to the piezoelectric vibrator storage container of the present invention,
On the bottom surface of the concave portion, at least near the center of the lower side of the step portion, a bottom ceramic coat layer extending between the bottom plate and the step portion is formed, so that the piezoelectric vibrator is provided inside the concave portion of the insulating base. When the metal lid is attached to the metal frame by welding after being housed, thermal stress due to welding is generated on the upper surface of the bottom plate which is in contact with the bottom of the concave portion of the insulating base and near the center of the lower side of the step. However, since the bottom ceramic coat layer functions as a reinforcing material for reinforcing the strength of the bottom plate, no crack is generated in the bottom plate. As a result, the reliability of hermetic sealing of the container is improved, and the piezoelectric vibrator accommodated in the container can be normally and stably operated for a long period of time.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A container for accommodating a piezoelectric vibrator according to the present invention will be described below. FIG. 1 is a cross-sectional view showing an example of an embodiment of a container for storing a piezoelectric vibrator according to the present invention. FIG. 2 is a view of the container for storing a piezoelectric vibrator shown in FIG. FIG. 3 is a perspective view, and FIG. 3 is a plan view of the container for accommodating the piezoelectric vibrator shown in FIG. 1 with the piezoelectric vibrator and a metal lid removed. In these figures, 1 is an insulating base made of a ceramic material, and 2 is a metal lid. A container for accommodating the piezoelectric vibrator 3 such as a crystal vibrator or a ceramic vibrator mainly includes the insulating base 1 and the metal lid 2.

The insulating base 1 is provided with a frame 1b on the upper surface of the bottom plate 1a, so that a substantially rectangular parallelepiped concave portion 4 for accommodating the piezoelectric vibrator 3 is formed on the upper surface. And recess 4
A pair of steps 5 to which the end of the piezoelectric vibrator 3 is attached are formed on the bottom surface of the inner end of the recess 4 in contact with the corners of the recess 4. On the bottom surface of the concave portion 4, a bottom ceramic coat layer 6 extending between the bottom plate 1 a and the step portion 5 is formed at least near the center of the lower side of the step portion 5.

The bottom plate 1a, frame 1b, and step 5 of the insulating base 1 are made of an electrically insulating material such as a sintered body of aluminum oxide, a sintered body of mullite, a sintered body of aluminum nitride, a sintered body of glass ceramic, or the like. For example, in the case of a sintered body made of aluminum oxide, an appropriate organic binder and a solvent are added to and mixed with raw material powders of aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc. It is formed by forming into a ceramic green sheet by forming it into a sheet by using the blade method, and then performing predetermined punching processing on the ceramic green sheet, laminating a plurality of these, and firing at a high temperature. You.

A wiring layer 8 is formed from the upper surface of the step 5 to the lower surface of the insulating substrate 1. Each electrode of the piezoelectric vibrator 3 is electrically connected to an area located on the upper surface of the step portion 5 of the wiring layer 8 via an adhesive 7.
Is connected to the wiring conductor of the external electric circuit board via solder, brazing material, or the like.

The wiring layer 8 is formed by adding a suitable organic binder or a solvent to a high melting point metal powder such as tungsten or molybdenum and mixing the resulting metal paste at a predetermined position on the ceramic green sheet for the insulating substrate 1 by screen printing. It is formed by printing and applying a predetermined pattern and firing this together with the ceramic green sheet for the insulating substrate 1.

The wiring layer 8 is preferably provided with a metal having excellent corrosion resistance and good conductivity, such as nickel or gold, having a thickness of 1 to 20 μm on the exposed outer surface by a plating method. Thereby, oxidation corrosion of the wiring layer 8 can be effectively prevented, and the bonding strength when the wiring layer 8 is bonded to the wiring conductor of the external electric circuit board via solder, brazing material, or the like can be improved.

The insulating base 1 has a frame-shaped metallized metal layer 9 formed on the upper surface of the frame 1b, and a metal frame 10 is brazed to the frame-shaped metallized metal layer 9. The frame-shaped metallized metal layer 9 is made of a refractory metal such as tungsten or molybdenum, and functions as a base metal layer when the metal frame 10 is joined to the frame 1b of the insulating base 1.

A metal paste obtained by adding a suitable organic binder or a solvent to a refractory metal powder such as tungsten or molybdenum is screened at a predetermined position on a ceramic green sheet for the insulating substrate 1. It is formed by printing and applying a predetermined pattern by a printing method and firing this together with a ceramic green sheet for the insulating substrate 1.

Further, the metal frame 10 joined to the frame-shaped metallized metal layer 9 functions as a base metal member for attaching the metal lid 2 to the insulating base 1 by welding. By welding to the metal frame 10 by a seam welding method, an electron beam method, or the like, the metal lid 2 is attached to the insulating base 1.

The metal frame 10 is made of a metal material such as an iron-nickel-cobalt alloy or an iron-nickel alloy.
An ingot of a nickel-cobalt alloy or the like is formed into a predetermined frame shape by rolling or punching.

On the bottom surface of the concave portion 4, a bottom ceramic coat layer 6 extending between the bottom plate 1a and the step portion 5 is formed at least near the center of the lower side of the step portion 5. The bottom ceramic coat layer 6 functions as a reinforcing member for preventing cracks generated in the bottom plate 1a when the metal lid 2 is welded to the metal frame 10.

Since the piezoelectric vibrator 3 is accommodated inside the concave portion 4 of the insulating base 1 by the formation of the bottom ceramic coat layer 6, the metal lid 2 is attached to the metal frame 10 by welding. At this time, even if thermal stress due to welding is generated in a portion of the bottom plate 1a that is in contact with the vicinity of the center of the lower side of the step portion 5 on the bottom surface of the concave portion 4 of the insulating base 1, the bottom ceramic coat layer 6 is formed in this portion. Since the strength of the bottom plate 1a is reinforced, no cracks occur in the bottom plate 1a. As a result, the reliability of hermetic sealing of the container is high, and the piezoelectric vibrator 3 housed inside the container can be normally and stably operated for a long period of time.

The minimum formation range of the bottom ceramic coat layer 6 is as follows. First, in the case where the step portion 5 has a pair of square shapes as shown in FIG. And about 50% of the length until each side contacts the frame 1a. The width of the formation is about 0.1 mm from the lower side of the step 5 to the outside of the step 5, and the width extending between the bottom plate 1a and the step 5 is about 0.1 mm.
It may be 0.1 mm.

If the bottom ceramic coat layer 6 is smaller than such a minimum formation range, the function as a strength reinforcing member for preventing cracks tends to be insufficient.

On the other hand, the maximum formation range of the bottom ceramic coat layer 6 is preferably as wide as possible without contacting the frame 1b. In a state where the bottom ceramic coat layer 6 is in contact with the frame 1b, when the ceramic green sheet serving as the frame 1b is laminated on the ceramic green sheet serving as the bottom plate 1a, the ceramic green sheet serving as the frame 1b is deformed. And may cause a leak.

In practice, when the stepped portion 5 has a pair of square shapes as shown in FIG. 2 as the formation length, each side is centered on the corner protruding inside the recess 4. Should be about 90% of the length before contacting the frame 1a. The width of the formation may be about 0.5 mm outside the step from the lower side of the step 5, and the width extending between the bottom plate 1a and the step 5 may be about 0.5 mm.

However, when the step portions 5 are formed as a pair as shown in FIG. 2, between the step portions 5, the bottom ceramic coat layer 6 is connected as shown by a dotted line in FIG. Alternatively, the bottom ceramic coat layers 6 formed on the lower sides of the pair of step portions 5 may be connected to each other to form an integral body.

Further, the thickness of the bottom ceramic coat layer 6 is preferably about 5 to 50 μm, and more preferably about 10 to 15 μm. If it is less than about 5 μm, it tends to be difficult to secure sufficient strength as a reinforcing member for preventing cracks. On the other hand, the thickness of the bottom ceramic coat layer 6 is
If the thickness exceeds about 50 μm, the step portion 5 to be laminated on the bottom ceramic coat layer 6 may not be properly laminated and may be deformed, so that good hermetic sealing cannot be obtained and the piezoelectric vibrator 3 is attached to the step portion 5. It tends to be unable to attach correctly. The thickness of the bottom ceramic coat layer 6 is 10 ~
When the thickness is 15 μm, a small amount can be applied to a uniform thickness.

The bottom ceramic coat layer 6 thus formed on the bottom surface of the concave portion 4 can be applied to a step portion having any shape. For example, as shown in a perspective view in FIG. For the step portion 5 having a shape, a bottom ceramic coat layer 6 may be formed near the center of the hypotenuse, and for a pair of arc-shaped step portions 5 as shown in a perspective view in FIG. The bottom ceramic coat layer 6 may be formed in the vicinity of the center of the lower side of the arc, respectively.
For one rectangular step 5 as shown in the perspective view, a bottom ceramic coat layer 6 may be formed near the center of the lower side.

The bottom ceramic coat layer 6 as described above
A ceramic paste obtained by adding an appropriate organic binder and a solvent to a ceramic powder having the same composition as the ceramic green sheet to be the bottom plate 1a is applied to a predetermined position of the ceramic green sheet to be the bottom plate 1a by a screen printing method or the like. Is formed by printing and applying a predetermined pattern using, followed by baking at a high temperature.

Thus, according to the container for accommodating the piezoelectric vibrator of the present invention, the piezoelectric vibrator 3 is attached to the step 5 formed on the bottom surface of the inner end of the substantially rectangular recess 4 of the insulating base 1 with the adhesive 7.
And the electrodes of the piezoelectric vibrator 3 are electrically connected to the wiring layer 8. Thereafter, the electrodes are connected to the frame-shaped metallized metal layer 9 formed around the recess 4 on the upper surface of the insulating base 1. The metal lid 2 is welded to the attached metal frame 10,
A piezoelectric device as a final product is obtained by hermetically sealing the piezoelectric vibrator 3 inside a container mainly including the insulating base 1 and the metallic lid 2.

At this time, the concave portion 4 of the container for storing the piezoelectric vibrator is used.
Since the bottom ceramic coat layer 6 is formed on the bottom surface of the metal frame 2, when the metal lid 2 is welded to the metal frame 10,
Even if a thermal stress is generated near the center of the lower side, cracks do not occur in the bottom plate 1a of the insulating base 1 because it is reinforced by the bottom ceramic coat layer 6. As a result, the reliability of hermetic sealing of the container can be enhanced, and the piezoelectric vibrator 3 housed inside the container can be operated normally and stably for a long period of time.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes may be made without departing from the spirit of the present invention. For example, although an example has been described in which the step portion 5 is provided only on one short side of the concave portion 4 of the piezoelectric vibrator storage container, the step portion 5 may be provided on both short sides.

[0032]

According to the container for accommodating the piezoelectric vibrator of the present invention, the bottom ceramic extending between the bottom plate and the step at the bottom of the recess of the insulating base, at least near the center of the lower side of the step. Since the coat layer is formed, when the piezoelectric vibrator is accommodated in the concave portion of the insulating base and the metal lid is welded to the metal frame to manufacture the piezoelectric device, the center of the lower side of the step portion of the bottom plate is formed. Even if thermal stress occurs due to welding in the vicinity, the bottom ceramic coat layer functions as a reinforcing material to reinforce the strength of the bottom plate, so that cracks do not occur in the insulating base and the reliability of hermetic sealing of the container is improved. The piezoelectric vibrator accommodated in the container can be normally and stably operated for a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of a container for accommodating a piezoelectric vibrator according to the present invention.

FIG. 2 is a perspective view of the container for accommodating the piezoelectric vibrator shown in FIG. 1 except for a lid and a piezoelectric vibrator.

FIG. 3 is a plan view of the container for accommodating the piezoelectric vibrator shown in FIG. 1, excluding a lid and a piezoelectric vibrator.

FIG. 4 is a perspective view showing another example of the embodiment of the piezoelectric vibrator storage container of the present invention.

FIG. 5 is a perspective view showing another example of the embodiment of the piezoelectric vibrator storage container of the present invention.

FIG. 6 is a perspective view showing another example of the embodiment of the piezoelectric vibrator storage container of the present invention.

FIG. 7 is a cross-sectional view illustrating an example of a conventional container for storing a piezoelectric vibrator.

8 is a perspective view of an essential part of the container for accommodating the piezoelectric vibrator shown in FIG. 7, excluding a lid and a piezoelectric vibrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base 1a ... Bottom plate 1b ... Frame 2 ... Metal lid 3 ... Piezoelectric vibrator 4 ... Depression 5 ... Stepped part 6 ... Bottom ceramic coat Layer 9: Frame-shaped metallized metal layer 10: Metal frame

Claims (1)

[Claims] An insulating base having a substantially rectangular parallelepiped recess for accommodating a piezoelectric vibrator provided on an upper surface of a bottom plate, and an insulating base formed on a bottom surface of an inner end of the recess. A stepped portion to which an end of the piezoelectric vibrator is attached on the upper surface, a frame-shaped metallized metal layer attached to the upper surface of the frame, and a metal frame joined to the frame-shaped metalized metal layer Body and
In the piezoelectric vibrator storage container, which is welded to the metal frame and includes a metal lid closing the recess, the bottom plate has a bottom plate and the bottom plate at least near the center of a lower side of the step portion. A container for accommodating a piezoelectric vibrator, wherein a bottom ceramic coat layer extending between the step and the step portion is formed.