JP2005175520A - Piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent airtightness of the inside of a crystal vibrator from being impaired, when the crystal vibrator is mounted on a printed wiring board. <P>SOLUTION: An alumina is coated on a metallized surface 21 between electrode terminals 6b, 6d formed from the outer bottom surface of a container main body 2 to its side surface and a joining surface 4 to form a convex portion 7 having insulating performance. By doing this, paste solder 62 of the electrode terminals 6b, 6d can be prevented from reaching the joining surface 4 when the crystal vibrator 1 is mounted on the printed wiring board 61. In this way, the high temperature solder 24 for bonding a lid 3 to the joining surface 4 can be prevented from being melted by the paste solder 62, and the airtightness of the inside of the main container main body 2 cannot be impaired. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface mount type piezoelectric vibrator.

In recent years, a surface mount device (SMD) that can be mounted on the surface of a printed circuit board on the device side is widely used as a crystal resonator or the like used in various electronic devices.
In order to improve the soldering strength and make the solder fillet visually visible, such a crystal unit is provided with cutouts at the four corners of the side, and electrode terminals are formed from the outer bottom surface to the cutouts, respectively. There is something like that (Patent Document 1).

5A and 5B are diagrams for explaining the structure of a conventional surface-mount type crystal unit. FIG. 5A is a top view, FIG. 5B is a front view, and FIG. Each outer bottom view is shown.
In FIG. 5 (a), in order to show the inside of the container main body, illustration of the lid joined to the upper surface of the container main body is omitted.
5A to 5C, a surface-mounted crystal resonator (hereinafter simply referred to as “crystal resonator”) 101 includes a crystal piece 50 in an airtight container including a container body 102 and a lid 3. Contained.

  The container main body 102 is made of ceramic, and as shown in FIG. 5B, a second ceramic layer 102b serving as a side surface is laminated on a peripheral portion of the first ceramic layer 102a serving as a bottom plate (base), thereby forming a flat plate. It is formed in a very shallow box shape that can accommodate a quartz crystal piece 50.

As shown in FIG. 5A, extraction electrodes 11 a and 11 b and a pedestal 12 are provided on the inner bottom surface of the container main body 102. The heights of the extraction electrodes 11a and 11b and the pedestal 12 are substantially the same.
The extraction electrode 11a is connected to the excitation electrode 50a formed on the upper surface side of the crystal piece 50, and the extraction electrode 11b is connected to the excitation electrode 50b formed on the lower surface side of the crystal piece 50.
Conductive adhesives 51 and 51 are used to connect the extraction electrodes 11a and 11b to the excitation electrodes 50a and 50b.
Thereby, the crystal piece 50 and the extraction electrodes 11a and 11b are electrically connected and mechanically held.

  A joining surface 104 as shown in FIG. 5A is formed on the upper edge of the container main body 102, and the metallic lid 3 is joined to the joining surface.

Further, as shown in FIG. 5C, four electrode terminals 106a, 106b, 106c, and 106d are provided at the four corners of the outer bottom surface of the container body 102.
Of these four electrode terminals 106 a to 106 d, for example, the electrode terminals 106 a and 106 c are connected to the excitation electrodes 50 a and 50 b of the crystal piece 50 through the extraction electrodes 11 a and 11 b in the container main body 102. The remaining two electrode terminals 106 b and 106 d are connected to the joint surface 104 of the container body 102. That is, the electrode terminals 106 b and 106 d are connected to the lid 3 joined to the container main body 102.
These electrode terminals 106b and 106d are connected to the ground on the device side to suppress the stray capacity (floating capacity) generated in the airtight container composed of the container main body 102 and the lid 3.

  Further, as shown in FIG. 5A, arc-shaped notches 105, 105,... Are formed at the four corners of the side surface of the container body 101, and the notches 105, 105,. The electrode terminals 106a to 106d are formed over.

  In this way, the notches 105, 105,... Are formed at the four corners of the side surface of the container body 102, and the electrode terminals 106a-106d are formed from the bottom surface of the container body 102 to the notches 105, 105,. When surface mounting is performed on the device-side substrate, it is possible to improve the soldering strength between the lands on the substrate side and the electrode terminals 106 a to 106 d of the crystal resonator 101. Further, the state of each solder fillet between each land on the mounting substrate side and the electrode terminals 106a to 106d of the crystal resonator 101 can be visually confirmed.

In forming the electrode terminals 106 a to 106 d on the side surface of the container main body 102, the electrode terminals 106 a and 106 c are connected to the excitation electrodes 50 a and 50 b of the crystal piece 50, and thus the first ceramic constituting the container main body 102. It is formed only in the notch portion of the layer 102a.
This prevents the electrode terminals 106a and 106c and the joint surface 104 of the container body 102 from being in electrical contact.

  On the other hand, since the electrode terminals 106b and 106d are electrically connected to the joint surface 104 of the container main body 102, the electrode terminals 106b and 106d are formed on the entire cutout portions of the first ceramic layer 102a and the second ceramic layer 102b constituting the container main body 102. Thus, the electrical connection between the electrode terminals 106b and 106d and the joint surface 104 of the container body 102 is made more reliable.

FIG. 6 is an enlarged view of the cross section of the electrode terminal 106b surrounded by the broken-line circle B in FIG. 5B, and the structure of the electrode terminal 106b will be described with reference to FIG. The structure of the electrode terminal 106d is also the same.
As shown in FIG. 6, first, the electrode terminal 106b is formed from the outer bottom surface of the first ceramic layer 102a constituting the container body 102 through the side surfaces of the first and second ceramic layers 102a and 102b. A metallized surface 21 is formed of tungsten over the upper surface of the layer 102b.
Then, Ni plating 22 is applied to the surface of the metallized surface 21, and gold (Au) plating 23 is applied to the surface of the Ni plating 22. Thereby, the electrode terminal 106b and the joint surface 104 are formed integrally.
The lid 3 joined to the joining surface 104 of the container body 102 is formed by applying Ni plating 32 to a metal member 31 such as Kovar. For joining the joint surface 104 of the container body 102 and the lid 3, high-temperature solder 24 made of a gold-tin alloy is used.

  Although not shown, the electrode terminals 106a and 106c are formed with a metallized surface 21 of tungsten from the outer bottom surface of the first ceramic layer 102a of the container body 102 to the side surface of the first ceramic layer 102a, and Ni plating is applied to the surface. Further, it can be formed by applying Au plating to the surface of Ni plating.

JP 2003-218265 A

In recent years, in the field of various electronic devices, particularly mobile communication devices, the size of devices has been remarkably reduced, and various electronic components such as crystal resonators constituting the devices have been required to be further reduced in size.
For example, when the shape of the crystal resonator shown in FIG. 5 is specifically exemplified, the outer dimensions L × B of the container body 102 are 3.2 × 2.5 mm to 2.5 × 2.0 mm, 2.0 ×. The size is reduced to 1.6 mm. The thickness (height) is also set to about 0.5 mm. In this case, the thickness of the first ceramic layer 102a of the container body 102 is about 0.15 mm, and the thickness of the second ceramic layer 102a is about 0.2 mm.

However, when the crystal resonator is further reduced in size (lowered) as described above, the airtightness of the crystal resonator is reduced when the crystal resonator is mounted on the printed circuit board 61 as shown in FIG. It was sometimes damaged.
Usually, when a crystal resonator is mounted on the printed circuit board 61, in order to connect the electrode terminals 106a to 106d of the crystal resonator to the lands of the printed circuit board 61, for example, paste solder made of an alloy of tin and copper (hereinafter referred to as a solder paste) , "Paste solder") 62 is used. When such a crystal unit is mounted on the printed circuit board 61, the paste solder 62 may climb up the electrode terminal 106 b on the side surface of the container body 102, and the paste solder 62 may reach the bonding surface 104 of the container body 102. . As a result, the high-temperature solder 24 that joins the lid 3 to the joint surface 104 is melted by the paste solder 62, and the airtightness inside the crystal unit in which the crystal piece 50 is accommodated is impaired.

  Accordingly, the present invention has been made in view of the above points, and provides a piezoelectric vibrator that does not impair the airtightness of the piezoelectric vibrator when the piezoelectric vibrator is mounted on a printed circuit board. With the goal.

  In order to achieve the above object, in the piezoelectric vibrator of the present invention, a lid is bonded to a bonding portion formed on the upper surface portion of the container body in order to hermetically seal the inside of the container body in which the piezoelectric piece is accommodated. In addition, a first type electrode terminal electrically connected to the electrode of the piezoelectric piece and a second type electrode terminal electrically connected to the joint are formed from the outer bottom surface to the side surface of the container body. In the piezoelectric vibrator, a convex portion is formed between the second type electrode terminal formed on the side surface of the container body and the joint portion.

According to the present invention as described above, the convex portion is formed between the second type electrode terminal formed on the side surface of the container main body and the joint portion to which the lid is joined. When the vibrator is mounted on the printed board, it is possible to prevent the solder used for connecting the printed board and the second type electrode terminal from reaching the joint portion of the container body.
As a result, when the piezoelectric vibrator is mounted on the printed circuit board, the solder of the joint joining the lid is melted when the solder of the second type electrode terminal reaches the joint, and the airtightness in the piezoelectric vibrator is melted. Can be prevented from being damaged.

  FIG. 1 is a perspective view showing the structure of a crystal resonator according to the present embodiment. FIG. 2 is a diagram for explaining the structure of the surface-mount type crystal resonator according to the present embodiment. FIG. 2 (a) is a top view, FIG. 2 (b) is a front view, and FIG. c) shows the bottom view of the outside. In FIG. 2A, in order to show the inside of the container main body, the illustration of the lid joined to the upper surface of the container main body is omitted.

A surface mount type (SMD) crystal resonator (hereinafter simply referred to as “crystal resonator”) 1 shown in FIG. 1 includes a crystal piece 50 inside a hermetically sealable container body 2 including a container body 2 and a lid 3. Is stored.
The container body 2 is made of, for example, ceramic, and as shown in FIG. 2B, the structure of the container main body 2 is a side surface at the peripheral edge of the rectangular first ceramic layer 2a serving as a base portion (bottom plate). By laminating the two ceramic layers 2b, a very shallow box shape capable of accommodating the flat crystal piece 50 is formed.

  The external dimension L × B of the crystal resonator 1 of this embodiment is about 2.0 × 1.6 mm, and the thickness (height) H is about 0.5 mm. In this case, the thickness of the first ceramic layer 2a is about 0.15 mm, and the thickness of the second ceramic layer 2b is about 0.2 mm.

As shown in FIG. 2A, extraction electrodes 11 a and 11 b and a pedestal 12 are provided on the inner bottom surface of the container body 2. The heights of the extraction electrodes 11a and 11b and the pedestal 12 are substantially the same.
The extraction electrode 11 a is connected to the excitation electrode 50 a formed on the upper surface side of the crystal piece 50, and the extraction electrode 11 b is connected to the excitation electrode 50 b formed on the lower surface side of the crystal piece 50.
Conductive adhesives 51 and 51 are used to connect the extraction electrodes 11a and 11b to the excitation electrodes 50a and 50b. Thereby, the crystal piece 50 and the extraction electrodes 11a and 11b are electrically connected and mechanically held.

  A joint surface 4 as shown in FIG. 2A is formed on the upper edge of the container body 2, and a metal lid 3 is joined to the joint surface. The structure of the joint surface 4 will be described later.

Moreover, as shown in FIG.2 (c), four electrode terminals 6a, 6b, 6c, 6d are provided in the four corners on the outer bottom face of the container main body 2.
Of these four electrode terminals 6a to 6d, for example, the electrode terminals 6a and 6c are first-type electrode terminals, and the excitation electrodes 50a and 50a of the crystal piece 50 are connected via the extraction electrodes 11a and 11b in the container body 2. 50b. The remaining two electrode terminals 6 b and 6 d are second type electrode terminals and are connected to the joint surface 4 of the container body 2. That is, the electrode terminals 6 b and 6 d are connected to the lid 3 joined to the container body 2. These electrode terminals 6b and 6d are connected to ground so as to suppress the stray capacity generated in the airtight container composed of the container body 2 and the lid 3.

  Further, as shown in FIG. 2A, for example, arc-shaped notches 5, 5... Are formed at the four side corners of the container body 2, and the notches 5, 5 are formed from the outer bottom surface of the container body 2. .. Electrode terminals 6a to 6d are formed over.

When the notches 5, 5,... Are formed at the four corners of the side surface of the container body 2 and the electrode terminals 6a-6d are formed from the bottom surface of the container body 2 to the notches 5, 5,. When mounted on the surface of the substrate on the device side, it is possible to improve the soldering strength between each land on the substrate side and the electrode terminals 6a to 6d of the crystal unit 1.
In addition, the state of each solder fillet between each land on the mounting substrate side and the electrode terminals 6a to 6d of the crystal resonator 1 can be visually confirmed.

  In forming the electrode terminals 6a to 6d on the side surface of the container main body 2, the electrode terminals 6a and 6c are connected to the excitation electrodes 50a and 50b of the crystal piece 50. The first ceramic layer 2a is formed only in the notch portion of the first ceramic layer 2a. Thereby, it is made to prevent that the electrode terminals 6a and 6c and the junction surface 4 of the container main body 2 contact electrically.

On the other hand, the electrode terminals 6b and 6d are electrically connected to the joining surface 4 of the container body 2. In this case, the electrode terminals 6b and 6d formed on the side surface of the container body 2 and the joining surface 4 are used. A convex portion 7 is formed by coating alumina between the two.
That is, the crystal resonator of the present embodiment is different from the conventional crystal resonator shown in FIG. 5 in that the convex portion 7 is formed between the electrode terminals 6b and 6d of the container body 2 and the bonding surface 4. Are different.

FIG. 3 is an enlarged view of the cross section of the electrode terminal 2b surrounded by the broken-line circle A in FIG. 2B. With reference to FIG. 3, the electrode terminal 6b of the crystal resonator of the present embodiment is used. , 6d will be described. Since the electrode terminal 6d has the same structure as the electrode terminal 6b, the illustration thereof is omitted.
As shown in FIG. 3, the electrode terminal 6b is connected to the second ceramic layer 2b from the outer bottom surface of the first ceramic layer 2a constituting the container body 2 through the side surfaces of the first and second ceramic layers 2a and 2b. The metallized surface 21 (conductor layer) is formed of tungsten over the upper surface of the metal layer. Thereby, the electrical connection between the electrode terminal 6b and the bonding surface 4 is obtained.

In addition, in the crystal resonator 1 of the present embodiment, the convex portion 7 is formed by coating alumina on the side surface of the second ceramic layer 2b on which the metallized surface 21 is formed. Then, Ni plating 22 is applied to the surface of the metallized surface 21 formed from the outer bottom surface to the side surface of the first ceramic layer 2a and the metallized surface 21 formed on the upper surface of the second ceramic layer 2b. The plating 23 is applied.
Thus, the convex portion 7 is formed between the electrode terminal 6 b and the bonding surface 4 while electrically connecting the electrode terminal 6 b and the bonding surface 4.

  Although not shown, the electrode terminals 6a and 6c are formed with a metallized surface 21 using tungsten from the outer bottom surface of the first ceramic layer 2a of the container body 2 to the side surface of the first ceramic layer 2a, and Ni plating is applied to the surface. Can be formed by applying Au plating to the surface of Ni plating.

As described above, in the crystal resonator 1 according to the present embodiment, the metallized surface 21 between the electrode terminals 6b and 6d formed on the side surface from the outer bottom surface of the container body 2 and the bonding surface 4 serves as an insulating member. The convex part 7 is formed using alumina.
In this case, for example, even when the crystal resonator 1 is lowered in height and the height of the crystal resonator 1 is about 0.5 mm, as shown in FIG. It is possible to prevent the paste solder 62 for connecting ˜6d to the land of the printed circuit board 51 from reaching the bonding surface 4.
As a result, the high-temperature solder 24 that joins the lid 3 to the joint surface 4 is not melted by the paste solder 62, and the airtightness in the crystal unit in which the crystal piece 50 is accommodated is not impaired.

  The paste solder 62 in this case is a paste solder made of an alloy of tin and copper as described above. The paste solder 62 may be either a lead type or a lead-free type. The high-temperature solder 24 is a gold-tin alloy solder that does not contain flux so as not to contaminate the inside of the container body 2 when the lid 3 is joined to the container body 2, for example.

In the present embodiment, the case where the electrode terminals 6a to 6d of the container main body 2 are provided in the notches 5, 5,... Formed at the four corners of the container main body 2 has been described as an example. The electrode terminals formed on the side surfaces of the container body 2 are not necessarily formed in the notches 5 and 5.
The present invention can be applied not only to a crystal resonator but also to a piezoelectric resonator using a piezoelectric piece such as a resonator.

1 is a perspective view of a crystal resonator according to an embodiment of the present invention. FIG. 3 is a top view, a front view, and an outer bottom view of a crystal resonator according to the present embodiment. It is the figure which expanded and showed the cross-sectional structure of the electrode terminal in the crystal oscillator made into this Embodiment. It is the figure which showed the mode when the crystal oscillator shown in FIG. 3 was mounted in the printed circuit board. It is a top view, a front view, and an outer bottom view of a conventional crystal unit. It is the figure which expanded and showed the cross-section of the electrode terminal in the conventional quartz oscillator. It is the figure which showed the mode when the crystal oscillator shown in FIG. 6 was mounted in the printed circuit board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Crystal oscillator, 2a 1st ceramic layer, 2b 2nd ceramic layer, 2 container main body, 3 lid | cover, 4 joint surface, 5 notch part, 6a-6d electrode terminal, 7 convex part, 11a 11b extraction electrode, 12 base, 21 Metallized surface, 22 23 Plating, 24 High-temperature solder, 31 Metal member (Kovar), 32 Nickel plating, 50a Excitation electrode, 50 Crystal piece, 51 Conductive adhesive, 61 Printed circuit board, 62 Paste solder

Claims (2)

In order to hermetically seal the inside of the container main body in which the piezoelectric piece is accommodated, a lid is bonded to the bonding portion formed on the upper surface of the container main body,
A first type electrode terminal electrically connected to the electrode of the piezoelectric piece and a second type electrode terminal electrically connected to the joint portion from the outer bottom surface to the side surface of the container body. In the formed piezoelectric vibrator,
A piezoelectric vibrator characterized in that a convex portion is formed between the second type electrode terminal formed on the side surface of the container body and the joint portion. 2. The piezoelectric vibrator according to claim 1, wherein high temperature solder is used for joining the lid and the container body.

Images