JP2000134055A - Airtight container for piezoelectric body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the airtight container for a piezoelectric body that is manufactured at a low cost without losing the mechanical strength. SOLUTION: A container main body 1 of the airtight container for a piezoelectric body is made of a metallic plate 11, an insulating film 2 is coated on the surface thereof and an electrical conductive film of connection electrodes 3a, 3b, an adhesion face 6 and electrode terminals 7a-7d is formed on the insulating film 2. Then the connection electrode 3a and the electrode terminals are connected by an electrical conductive line 12a via a throughhole so as to maintain the air-tightness and the mechanical strength equal to and more than the case with the container main body 1 that is made of a ceramic and the profile of the main body is made thin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airtight container for a piezoelectric body which can house a piezoelectric element such as a quartz oscillator in an airtight state.

[0002]

2. Description of the Related Art Generally, a piezoelectric element such as a quartz oscillator, which has been used as a frequency control element of various electronic devices, is generally housed in a container having a vacuum state or a state filled with an inert gas such as nitrogen. It needs to be hermetically sealed. For this reason, various airtight containers have been proposed, but as the airtight container for the piezoelectric body, a ceramic container made of alumina having excellent mechanical strength characteristics has been conventionally used.

Here, an example of the structure of a conventional airtight container for a piezoelectric body used for a surface-mount type crystal unit will be described with reference to FIG. FIG. 8A is an assembled perspective view of a conventional surface-mount type crystal unit, and FIG. 8B is a cross-sectional view of the dashed line XX in FIG. These FIG.
The airtight container of the surface mount type crystal unit shown in FIGS. 1A and 1B includes a container body 100 and a lid 110. As shown in FIG. 1B, the container body 100 has a flat lower ceramic layer 101 serving as a substrate, an intermediate ceramic layer 102 laminated to form a step in the lower ceramic layer 101, It is formed of a frame-shaped upper ceramic layer 103 laminated on the ceramic layer 102. Then, on the upper ceramic layer 103,
Metallized processing is performed as a joint portion 104 for sealing the lid 110. Note that a metal seal ring or the like may be brazed to the joining surface 6 as a joining member.

[0004] Two connection electrodes 105 a and 105 b are provided on one intermediate ceramic layer 102 in the container body 100, and these connection electrodes 105 a and 105 b are connected to the electrodes of the quartz piece 20 by a conductive adhesive 108. Each is connected. As a result, the electrodes of the crystal blank 20 are electrically connected to the connection electrodes 105a and 105b, and the crystal blank 20 is mechanically held in the container. Also, the other intermediate ceramic layer 102 in the container body 100
On the top, a part of the crystal piece 20 is placed as shown,
Thereby, the crystal blanks 20 are made parallel. That is, the other intermediate ceramic layer 102 on which the connection electrodes 105a and 105b are not formed functions as a receiving surface for relieving the stress of the crystal blank 20 due to impact or the like.

Further, a plurality of electrode terminals 107 are provided from the outer bottom surface to the side surface of the ceramic layer forming the container body 100 so that the surface mount type crystal unit can be mounted as a chip component on a mounting substrate. I have. One of these electrode terminals 107 is connected to the connection electrode 105a by a conductive line 106 as shown in FIG.

Therefore, after the crystal blank 20 is set in the container body 100 having such a structure, the main body 10
For example, a flat-plate-shaped lid 110 is joined to the upper opening of the O, and the inside of the lid 110 is hermetically sealed to form a surface-mount type crystal unit.

[0007]

In recent years, with the miniaturization and cost reduction of various electronic devices, there has been a demand for further miniaturization and cost reduction of various electronic components constituting the electronic devices. Electronic components constituted by piezoelectric elements such as quartz filters are no exception. In particular, further reduction in the thickness of electronic components is required.

However, in order to reduce the size of the surface-mount type crystal unit, the container body 1 in which the crystal blank 20 is stored is required.
It is necessary to secure a certain amount of space in the area 00 in order to maintain the characteristics. Therefore, in order to realize miniaturization, the thickness of the bottom surface (current thickness, about 0.25 mm) is inevitably required. Need to be thinner. However, the container body 1
As is well known, the ceramic forming 00 is a brittle material, and is a powder sintered product. Therefore, when the thickness is reduced, the strength of the ceramic is significantly reduced, and warpage or cracking occurs during firing. Is more likely to occur. For this reason,
Container body 1 without impairing airtightness, mechanical strength characteristics, etc.
It was difficult to make the bottom of 00 thin.

Further, the container body 100 as described above is
Since the container body 1 is made of a ceramic layer,
When manufacturing the sheet No. 00, a conductor is placed in a predetermined place on a green sheet (for example, a sheet obtained by suspending aluminum powder in a solvent, a plasticizer, or the like, and drying the sheet) by a die or the like. After pattern printing of the film, it is necessary to laminate, press and fire. In addition, the conductor film (conductive line 106) for connecting the connection electrode 104 and the electrode terminal 107 formed by pattern printing of the conductor film had to be separately manufactured using a dedicated jig. As described above, the production of the conventional container body 100 is very troublesome, and it has been very difficult to reduce the cost.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made without impairing the airtightness or mechanical strength of an airtight container used for a piezoelectric body or the like.
It is another object of the present invention to provide an airtight container for a piezoelectric body that can be manufactured at low cost.

In order to achieve the above object, the present invention relates to a hermetically sealed container for a piezoelectric body, in which a container body and a lid are joined to hermetically seal a piezoelectric body housed therein. A conductive film for a connection electrode, a conductive film for a sealing agent, and a conductive film for an electrode terminal are formed on the insulating film while forming an insulating film on the surface of the metal plate. And the conductive film for an electrode terminal are connected by a conductive line through a through hole formed in a metal plate.

Further, among the metal plate, the conductive film for sealing, and the conductive film for the electrode terminal, the conductive film for the electrode terminal, which is a ground terminal, and the metal plate are electrically connected. The insulating film is formed by forming a glass-based material on the surface of a metal plate by sputtering or vapor deposition. Further, the metal plate is bent upward so that its peripheral portion is joined to the peripheral portion of the lid. A low melting point brazing material was provided on the sealing conductive film of the container body to which the lid was joined.

According to the present invention, the container body is formed of metal, an insulating film is formed on the surface of the metal body, and the conductive film for connection electrodes, the conductive film for sealing, and the conductive film for electrode terminals are formed on the insulating film. By forming a film, it is possible to reduce the thickness of the container while maintaining the same or higher airtightness and mechanical strength as compared with the case where the container body is formed of ceramic.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an airtight container for a piezoelectric body according to the present invention will be described. In the present embodiment, a case will be described as an example where a quartz oscillator is formed using the hermetic container for a piezoelectric body of the present invention. FIG. 1 is an upper perspective view of a crystal resonator according to the present embodiment before being assembled, and FIG.
3 is a cross-sectional view of the AA line shown in FIG.

As shown in FIGS. 1 to 3, the hermetic container for a piezoelectric body according to the present embodiment comprises a container body 1 and a lid 10. The base of the container body 1 is made of, for example, Kovar (KV), a 42-6 alloy (42% Ni, 6% Cr, remaining Fe, etc.), and has a very small thickness (for example, about 0.
It is formed of a flat metal plate 11. On the surface of the metal plate 11, an extremely thin (for example, about 0.01 mm thick) insulating film 2 is formed by an insulating member such as glass, glass ceramic, ceramic, or resin. Further, a metallizing process is performed on the insulating film 2 by using a general conductive member such as tungsten, molybdenum manganese or the like, and conductive films for connection electrodes (hereinafter, referred to as “connection electrodes”) 3a and 3b, A conductive film (hereinafter, referred to as “joining surface”) 6 and a conductive film for electrode terminals (hereinafter, referred to as “electrode terminals”) 7a to 7d are formed.

An upper electrode 20a and a lower electrode (not shown) of the crystal blank 20 are bonded to the connection electrodes 3a and 3b by conductive adhesives 4a and 4b, respectively. At a position facing the connection electrodes 3a and 3b, a pedestal 5 formed of, for example, an insulating film for holding the other end of the crystal blank 20 is provided, and the pedestal 5 holds the crystal blank 20 horizontally. At the same time, the stress of the crystal blank 20 against impact or the like is relieved. The electrodes of the crystal blank 20 are formed such that the upper electrode 20a is connected only to the connection electrode 3a and the lower electrode is connected only to the connection electrode 3b.

The joining surface 6 is provided on the periphery of the container body 1 for joining the lid 10 to the container body 1. On this joining surface 6, for example, a brazing material such as silver which melts at a low temperature is used. Is provided. The electrode terminals 7a to 7d are provided on the lower side of the container main body 1 so that the crystal unit can be surface-mounted on a printed wiring board. For example, the electrode terminals 7a are formed through through holes 11a formed in the metal plate 11. Is connected to the connection electrode 3a by the conductive line 12a through the electrode terminal 7b.
Is connected to the connection electrode 3b by a conductive line via a through hole (not shown). The electrode terminal 7c is a conductive line 12
b, it is connected to the metal plate 11, and the metal plate 11 is also connected to the joint surface 6 by the conductive line 12c. Since the insulating film 2 is formed between the conductive line 12a and the metal plate 11, the metal plate 11 and the conductive line 12a are electrically insulated, and the through hole 11a is closed. I have.

Further, since the crystal unit according to the present embodiment is surface-mounted on a printed wiring board or the like, for example, gold plating is applied to the electrode terminals in order to improve solderability with electrodes of the printed wiring board. I have to. Therefore, in the stage of finishing the container body 1, the connection electrodes 3
Gold plating is applied to the surfaces a, 3b, the joint surface 6, and the electrode terminals 7a to 7d. However, the connection electrodes 3a,
This is not the case when the conductive film 3b, the bonding surface 6, and the electrode terminals 7a to 7d are formed by a conductive member having good solderability.

The lid 10 is formed of, for example, a metal such as Kovar (KV) or a clad material in which the surface of a metal such as Kovar is plated with nickel. As can be seen from FIGS. 1 and 2, the shape is a dome shape with the periphery bent downward, and a flange surface 10a is formed around the periphery. The lid 10 may have various structures, such as a clad material in which a metal plate and a gold-tin alloy (high-temperature solder) are adhered by rolling, or a metal whose surface is plated with nickel, silver, or the like. Since it differs depending on a sealing method or the like for joining the lid 10 to the main body 1, the lid 10 may have an optimal structure suitable for various sealing methods described later.

When the lid 10 is joined to the container body 1, the container 10 is passed through the reflow furnace with the container body 1 and the lid 10 superposed. As a result, the silver brazing material on the bonding surface 6 is melted, the lid 10 is bonded to the bonding portion 6 of the container body 1, and the inside thereof is hermetically sealed, so that the surface-mounted crystal resonator according to the present embodiment is provided. Is configured.

In the hermetically sealed container of this embodiment having such a structure, the container main body 1 is a metal plate 11 having an extremely thin insulating film 2 formed on the surface thereof. The thickness of the bottom surface of the container body 1 is extremely thin (the thickness of the metal plate is about 0.03 mm, and the thickness of one side of the insulating film is about 0.01 mm, while securing the mechanical strength and airtightness equal to or higher than the case where it is formed). Approximately 0.05m in total
m). As a result, the thickness of the entire hermetic container can be reduced while securing a space in the hermetic container in which the crystal blank 20 is stored.

In the airtight container of the present embodiment, the metal plate 11 constituting the container body 1, the joint 6 to which the lid 10 is joined, and the electrode terminal 7c serving as a ground electrode are connected to a conductive line. 12b and 12c, the crystal unit can be shielded by an airtight container, and the frequency fluctuation due to noise from the outside and the influence of the frequency fluctuation on other electronic components due to the radiation from the crystal unit. Can be reduced.

Here, the procedure for producing the above-described container body 1 will be briefly described with reference to the schematic diagram shown in FIG. When the container body 1 shown in FIG. 1 is manufactured, the through hole 11 is provided at a required position as shown in FIG.
On the surface of the metal plate 11 on which a is formed, a film is formed by, for example, a sputtering method or a vapor deposition method to form an insulating film 12 as shown in FIG. In addition, on the surface of the metal plate 11,
For example, it is conceivable to form an insulating film 12 by applying an insulating member to a resin or the like.

Next, among the insulating films 2 formed on the surface of the metal plate 11, for example, the through holes 11a for forming the conductive lines 12a are formed.
The central portion of the insulating film 2 and the portion of the insulating film 2 where the conductive lines 12b and 12c are to be formed are removed by, for example, a laser trimming method or the like to form an opening 2 as shown in FIG.
a and openings 2b and 2c are formed. Then, conductive lines 12a to 12c as shown in FIG. 4D are formed in the openings 2a and the openings 2b and 2c by, for example, a sputtering method or a vapor deposition method. As shown, a conductive film that becomes the bonding surface 6, the connection electrode 3, and the electrode terminal 7,
And an insulating film serving as the pedestal 5 is formed.
It may be fired at a relatively low temperature of 000 degrees.

When the container body 1 is manufactured as described above, the insulating film 2 may be formed on the surface of the metal plate 11, and the conductor film and the insulating film may be formed thereon in that order. A manufacturing method can be adopted. Therefore, conventionally,
Necessary when forming the container body with ceramic,
For example, there is no need for complicated conductor forming work such as installation of a conductive line and preparation of a jig necessary for the work, and the steps of laminating and crimping ceramics are not required, so that production efficiency can be greatly improved. become.

As a method of manufacturing the container body 1, for example, instead of forming the insulating film 2 on the entire surface of the metal plate 11, masking is performed on portions corresponding to the openings 2a and the openings 2b and 2c. After that, the step of forming the insulating film 2 and removing the unnecessary insulating film 2 by laser trimming or the like may be omitted. That is, FIG. 4 (a) → (c) → (d)
→ It is also possible to manufacture the container body 1 of this example by the procedure of (e).

Next, another embodiment of the hermetic container for a piezoelectric body of the present invention will be described with reference to FIGS. In this case, a case where a quartz oscillator is formed will be described as an example. FIG. 5 is an upper perspective view before assembling a crystal unit according to another embodiment of the present invention, and FIG.
It is sectional drawing which looked at the B line in the arrow direction. In addition, FIG.
The same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

Each of the piezoelectric airtight containers shown in FIGS. 5 and 6 includes a container body 31 and a lid 40. The base of the container body 31 is the metal plate 11 as described above. It has a box shape (concave shape) whose periphery is bent upward. Further, the surface thereof is covered with the insulating film 2 except for the bonding surface 6. On the other hand, the shape of the lid 40 is a flat plate.

Also in this case, since the inside of the container can be hermetically sealed by joining the lid 40 to the joint surface 6 of the container body 31, the mechanical strength and the airtightness in the container are ensured in the same manner as described above. In addition, the thickness of the bottom surface of the container body 31 can be extremely reduced, and the thickness of the entire hermetic container can be reduced.

Further, since such a container body 31 can be realized by a procedure substantially similar to the procedure shown in FIG. 4, an integrated manufacturing method using a line can be adopted, and the production efficiency is greatly increased as described above. Can be improved.

Such a piezoelectric airtight container of the present invention can be applied to various shapes such as a container having a flat or box shape or a lid having a flat or dome shape. In addition, various methods can be used as a sealing method of joining the container body and the lid and sealing the inside thereof.

Hereinafter, the relationship between the structure of the airtight container and the sealing method will be briefly described with reference to FIG. Examples of the hermetic sealing method for joining the lid to the container body and hermetically sealing the inside thereof include, for example, parallel seam welding, projection resistance welding, electron beam welding, laser beam welding, low-temperature brazing, and soldering. There are various known seals, a low melting point glass seal method, an adhesive seal method, and the like.

For example, when sealing is performed by a parallel seam welding method in which a lid is superimposed on a container main body and then a current is applied while applying a load to the joint surface and sealing is performed by a parallel seam welding method, as shown in FIG. If the shape of the main body is box-shaped, it is preferable that the shape of the lid be any of a flat plate and a dome shape.
It should be noted that even when the container body is a flat plate, it is possible depending on the case if the lid is formed in a dome shape with a flange. Further, when sealing is performed by a projection resistance welding method capable of joining with a load larger than the parallel seam welding method, as shown in FIG. 7, the container body is formed in a box shape with a flange, and the lid body is formed as a flat plate or a flat plate. It is preferable to use a dome shape with a flange.

For example, when sealing is performed by an electron beam welding method or a laser beam welding method in which the joint surface between the container body and the lid is irradiated with an electron beam or a laser beam and joined.
If the container main body is formed in a box shape as shown in FIG. 7, it is preferable that the lid is formed in any of a flat plate and a dome shape.

When sealing is performed by the parallel seam welding method, the projection resistance welding method, the electronic boom method, or the laser beam method, a metal cover such as Kovar is plated with a silver brazing material as a cover. Is more preferable.

Also, a low-temperature brazing method in which a low-melting brazing material such as silver is formed on the joint surface between the container body and the lid, or a solder seal joined by using solder, gold tin (high-temperature solder), or the like. In the case of sealing by a method, the container main body and the lid are preferably in any shape such as a flat plate and a box shape, a flat plate and a dome shape as shown in FIG. In this case, it is more preferable to use a clad material in which a metal such as Kovar is plated with a silver brazing material or a clad material in which a metal and a gold-tin alloy (high-temperature solder) are bonded by rolling as a cover. .

In the case of a low-melting glass material or a low-melting glass sealing method or an adhesive sealing method of bonding with an adhesive, the container body and the lid are flat or box-shaped or flat as shown in FIG. Any shape, such as a dome shape or the like, is suitable.

In the present embodiment, the case where a quartz oscillator is formed using the hermetic container for a piezoelectric body of the present invention has been described by way of example. However, the present invention is not limited to this. The hermetic container for use can be applied as an hermetic container for various electronic components such as a quartz filter formed of a piezoelectric element. Further, the present invention can be applied as an airtight container for various electronic components on which surface acoustic waves, semiconductor elements, integrated circuits, and the like are mounted.

[0039]

As described above, in the hermetic container for a piezoelectric body of the present invention, the container body is formed of a metal plate,
An insulating film is formed on the surface, and a conductive film for connection electrodes, a conductive film for sealing, and a conductive film for electrode terminals are formed on the insulating film. Even if the airtightness and the mechanical strength are equal or higher, the thickness can be reduced. In addition, since the container body can be manufactured by forming an insulating film on the surface of a metal and then forming a conductive film on the insulating film, the integrated production method by line is adopted, and the production efficiency is greatly improved, and Cost reduction can be realized.

In addition, by conducting the metal plate and the sealing conductive film, and the conductive film for the electrode terminal serving as the ground terminal and the metal plate, the airtight container of the present invention can provide a shielding effect. There are advantages too.

[Brief description of the drawings]

FIG. 1 is an upper perspective view of an airtight container for a piezoelectric body according to an embodiment of the present invention before assembly.

FIG. 2 is a cross-sectional view of the dashed line XX shown in FIG.

FIG. 3 is a lower perspective view of the piezoelectric airtight container of the present embodiment.

FIG. 4 is a diagram schematically illustrating an example of a procedure for manufacturing the hermetic container for a piezoelectric body of the present embodiment.

FIG. 5 is an upper perspective view of a piezoelectric airtight container according to another embodiment of the present invention before assembling.

6 is a cross-sectional view of the alternate long and short dash line YY shown in FIG.

FIG. 7 is an explanatory diagram of a relationship between a structure of a container body and a lid and a sealing method.

FIG. 8 is an explanatory view of the structure of a conventional airtight container for a piezoelectric body.

[Explanation of symbols]

1 31 container main body, 2 insulating film, 3a 3b connection electrode, 4a 4b conductive adhesive, 5 pedestal, 6 bonding surface, 7 electrode terminal, 10 40 lid, 11 metal plate,
11a through hole, 12a 12b 12c conductive line,
20 crystal pieces

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Ando 4-20 Komukai Nishimachi, Saiwai-ku, Kawasaki-shi, Kanagawa F-term F-term (reference) 5J108 BB02 EE03 EE04 EE07 FF11 GG03 GG09 GG15

Claims (5)

[Claims] 1. An airtight container for a piezoelectric body capable of hermetically sealing a piezoelectric body housed therein by joining a container body and a lid, wherein the container body is formed of a metal plate, An insulating film is formed on the surface of the plate, and a conductive film for a connection electrode, a conductive film for sealing, and a conductive film for an electrode terminal are formed on the insulating film. A hermetic container for a piezoelectric body, wherein the hermetic container is connected to a conductive film via a conductive line via a through hole formed in the metal plate. 2. The method according to claim 2, wherein, among the metal plate, the sealing conductive film, and the electrode terminal conductive film, the electrode terminal conductive film serving as a ground terminal is electrically connected to the metal plate. The airtight container for a piezoelectric body according to claim 1, wherein: 3. The airtight container for a piezoelectric body according to claim 1, wherein the insulating film is formed by forming a glass-based material on the surface of the metal plate by sputtering or vapor deposition. 4. The airtight container for a piezoelectric body according to claim 1, wherein the metal plate is bent upward so that a peripheral portion thereof is joined to a peripheral portion of the lid. 5. The airtight container for a piezoelectric body according to claim 1, wherein a low melting point brazing material is provided on the sealing conductive film of the container body to which the lid is joined.