JP3303292B2 - Surface mount type piezoelectric vibration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package structure of a surface mount type piezoelectric vibrating device such as a crystal unit and a crystal filter.

[0002]

2. Description of the Related Art Piezoelectric vibrating devices such as quartz oscillators are required to be surface-mounted so that they can be automatically mounted on a circuit board, and to be rapidly downsized as electronic devices to be mounted are downsized. In terms of function, there is a demand for a high-performance and highly-reliable one with a small frequency fluctuation, stable electric characteristics.

[0003] Even if the crystal unit is limited to a surface mount type, a variety of support forms are adopted depending on the application and the like. For example, a crystal vibration plate is directly mounted on the electrode pad in the package and fixed with a conductive bonding material, or a solid support having no buffer function, or a support having a buffer function There is. If there is room in the package, it is generally preferable to use a support having a buffer function from the viewpoint of impact resistance, but from the viewpoint of miniaturization of the crystal unit and easy mounting of the crystal plate, It is rather desirable to directly mount on the electrode pads in the package.

However, since the structure in which the crystal vibration plate is directly mounted on the electrode pad in the package does not have a buffer function, the mounting position of the crystal vibration plate and the conductive bonding for electrically and mechanically connecting the crystal vibration plate and the electrode pad are not provided. There is a need to perform the application of the material more accurately. In particular, in the case of the cantilever holding structure in which the electrode is led out only at one end in the long side direction, the quartz vibrating plate is liable to have a problem due to its prescription. For example, if the mounting position of the crystal oscillator is shifted while being in contact with the package due to the inclination of the crystal oscillator, etc., if an external impact is applied to the crystal oscillator after commercialization, it will not be applied to the package. In addition, there is a problem that the shock directly adheres to the quartz vibrating plate and causes deterioration of electrical characteristics such as cracking or chipping of the quartz vibrating plate. In addition, the applied amount of the conductive bonding material that electrically and mechanically connects the crystal vibration plate and the electrode pad is too large, or the applied amount of the conductive bonding material varies, thereby causing a short circuit accident and a deterioration in CI value. However, there is also a problem that the electrical characteristics such as the above are deteriorated. Also, if the amount of the conductive bonding material that electrically and mechanically connects the crystal diaphragm and the electrode pad is too small, not only the CI value is deteriorated, but also the conductive bonding material is cracked,
There were problems such as the detachment of the quartz diaphragm. further,
When solder is used as the conductive bonding material, soldering defects such as potato (potato solder), too much solder flow, and insufficient soldering may be caused. The potting is applied in a state where air bubbles enter the solder or the solder is not completely melted. If the solder is applied in this state, the mechanical strength of the solder is weak, and the solder is easily detached by impact or vibration, which causes poor conduction. If the solder flows too much, problems such as short circuits tend to occur. When solder is insufficient, like solder, it is easily detached due to impact or vibration, which causes poor conduction.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is directly mounted on an electrode pad in a package in which a piezoelectric vibration device can be miniaturized and a piezoelectric vibration plate can be easily mounted. It is an object of the present invention to improve the reliability of a surface-mount type piezoelectric vibration device by more accurately performing a mounting position of a piezoelectric vibration plate and a coating state of a conductive bonding material.

[0006]

In order to solve the above-mentioned problems, the present invention provides a method for supporting a bottom surface and an inner wall surface for accommodating a piezoelectric vibrating plate, and at least one end of the piezoelectric vibrating plate in a long side direction. A package having a stepped portion, a package having an open top, a piezoelectric vibrating plate electrically connected to an electrode pad formed on the stepped portion and a conductive bonding material, and having excitation electrodes formed on the front and back surfaces; In the surface-mount type piezoelectric vibration device comprising:
A convex portion that is in contact with the central portion in the short side direction of the electric diaphragm and a narrow portion corresponding to the short side width of the piezoelectric diaphragm are formed .
The central portion of the piezoelectric diaphragm in the short side direction is defined as the narrow portion.
As a result, the inner wall surface of the step portion is positioned on the convex portion.
And the center of the piezoelectric diaphragm in the short side direction,
By contacting the protrusion on the inner wall surface of the step portion,
Form gaps at the steps on both ends of the piezoelectric diaphragm in the short side direction,
The conductive bonding material flows into the gap of the step portion,
The application state of the electrically conductive bonding material can be confirmed .

[0007] By forming a convex portion in contact with the piezoelectric vibrating plate on the inner wall surface of the step portion at the center of the piezoelectric vibrating plate in the short side direction, both end portions in the short side direction of the piezoelectric vibrating plate are provided. A gap having a certain capacity is formed, and the piezoelectric vibrating plate is positioned on the step portion of the package with gaps formed at both ends in the short side direction. Further, by forming a narrow portion corresponding to the width of the short side of the piezoelectric vibrating plate on the inner wall surface of the step portion, it is difficult for the piezoelectric vibrating plate to be shifted or inclined in the short side direction. The narrow portion of the inner wall surface is positioned such that the center of the piezoelectric vibrating plate in the short side direction is positioned on the convex portion of the inner wall surface, and both end portions of the piezoelectric vibrating plate in the short side direction, It is positioned in the gap with good balance. Then, a conductive bonding material for electrically and mechanically bonding the electrode pad formed on the step portion and the piezoelectric vibration plate flows into the gap, so that an application state of the conductive bonding material can be confirmed. Become.

According to a second aspect of the present invention, the piezoelectric vibrating plate has a one-sided electrical connection structure in which electrodes are led out only at one end in the long side direction.

[0009] With the above configuration, in addition to the above-mentioned functions and effects, the convex portion of the inner wall surface restricts the conductive bonding material from flowing out in the gaps at both ends, and the gap between the electrodes led out only at one end in the long side direction. To prevent short circuit.

According to the present invention, when solder is used as the conductive bonding material, it is possible to recognize the solder application state or the solder melting state, and to determine the soldering state such as squatting, excessive solder flow, insufficient soldering, and the like. Failure can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to the drawings, taking a surface mount type crystal unit as an example. FIG. 1 is an exploded perspective view showing a first embodiment of the present invention, and FIG. 2 is a plan view showing a state where the quartz plate of FIG. 1 is mounted. The lid used for hermetic sealing is not shown.

The quartz vibrating plate 1 is formed of an AT-cut quartz vibrating plate and has a rectangular shape. Excitation electrodes 11 and 12 are formed on the front and back surfaces, and extraction electrodes 11a and 1 that lead these excitation electrodes to one end in the long side direction of the quartz plate.
2a is formed by means such as a vacuum evaporation method.

The package 2 has a rectangular parallelepiped shape with an opening at the top as a whole, and includes a package base 20 made of ceramic as a bottom surface and a package peripheral wall 21 as a wall surface.
And a step portion 22 on which the quartz vibrating plate is mounted. The inner wall surface on which the step portion is formed has a convex portion 211 formed at the center of the end in the long side direction, and the both ends in the short side direction correspond to the short side width dimension of the piezoelectric vibration plate. Narrow portions 212 and 213 are formed so as to partially protrude. The width between the narrow portions is slightly larger than the width in the short side direction of the quartz plate, and is preferably 1.05 to 1.15 times the width of the quartz plate. If the ratio is smaller than the above-mentioned ratio, the insertion and positioning of the quartz plate into the package become difficult, and the workability is reduced. On the other hand, if the ratio is larger than the above-mentioned ratio, the quartz-crystal vibrating plate is liable to be adversely affected by the displacement and inclination in the short side direction. An electrode pad 2 is provided on the upper surface of the step.
21 and 222, and a metal ring 2 made of Kovar or the like used for hermetic bonding is provided on the upper portion of the peripheral wall 21.
3 are formed. The package 2 is integrally formed by firing using a ceramic lamination technique. The metal ring 23 is plated with a metal such as nickel.

Thereafter, the crystal vibrating plate 1 is mounted on the step 22 and the lead-out electrodes 11a and the electrode pads 221 and the lead-out electrodes 12a and the lead-out electrodes 12a are connected by a conductive bonding material D such as solder or conductive resin adhesive. The electrode pads 222 are each electrically and mechanically joined. Then, although not shown, the metal lid and the metal ring 23 of the package are hermetically sealed by joining means such as seam welding. The hermetic sealing means may use a welding method such as an electron beam. Further, the quartz vibrating plate is not limited to a rectangular one, but may be a tuning fork type as shown in the second embodiment.
The piezoelectric vibration plate is not limited to a crystal vibration plate, but may be another piezoelectric single crystal plate or a piezoelectric ceramic plate.

Next, a second embodiment of the present invention will be described.
Similarly, a crystal resonator will be described as an example with reference to the drawings. FIG. 3 is an exploded perspective view showing the second embodiment, and FIG. 4 is a plan view showing a state in which the quartz plate of FIG. 3 is mounted. First
The same components as those of the embodiment have been described using the same numbers.

The quartz vibrating plate 3 is made of a tuning-fork type quartz vibrating piece that bends and vibrates, and is configured to include legs 31, 32 and a base 33. Excitation electrodes (not shown) are formed around the legs, and extraction electrodes (not shown) for leading these excitation electrodes to one end in the long side direction of the quartz plate.
Is formed by means such as a vacuum evaporation method.

The package 2 has a rectangular parallelepiped shape with an open top as a whole, and includes a package base 20 as a bottom surface made of ceramic and a package peripheral wall 21 as a wall surface.
It is composed of steps 24 and 25 on which the quartz plate is mounted. The inner wall surface on which the step portions are formed has a convex portion 214 formed at the center of the end in the long side direction, and the both end portions in the short side direction correspond to the short side width dimension of the piezoelectric vibration plate. Narrow portions 215 and 216 are formed.
The width between the narrow portions is slightly larger than the width in the short side direction of the quartz plate, and is preferably 1.05 to 1.15 times the width of the quartz plate. If the ratio is smaller than the above-mentioned ratio, the insertion and positioning of the quartz plate into the package become difficult, and the workability is reduced. On the other hand, if the ratio is larger than the above-mentioned ratio, the quartz-crystal vibrating plate is liable to be adversely affected by the displacement and inclination in the short side direction. An electrode pad 24 is provided on the upper surface of each step.
1, 251 are formed, and a metal ring 2 made of Kovar or the like used for hermetic joining is provided on the upper part of the peripheral wall 21.
3 are formed. The package 2 is integrally formed by firing using a ceramic lamination technique. The metal ring 23 is plated with a metal such as nickel.

Thereafter, the base 33 of the quartz vibrating plate 3 is mounted on the steps 24 and 25, and the respective lead-out electrodes (not shown) and the electrode pads are connected by a conductive bonding material D such as solder or conductive resin adhesive. 241 and 251 are electrically and mechanically connected to each other. Then, although not shown, the metal lid and the metal ring 23 of the package are hermetically sealed by joining means such as seam welding. The hermetic sealing means may use a welding method such as an electron beam. Further, the quartz vibrating plate is not limited to the tuning fork type, but may be a rectangular one as shown in the first embodiment. The piezoelectric vibration plate is not limited to a crystal vibration plate, but may be another piezoelectric single crystal plate or a piezoelectric ceramic plate.

Further, in the second embodiment of the present invention, the step portion on which the quartz vibrating plate 3 is mounted is divided into two, and each step portion 2
By forming the groove 26 between 4 and 25, the capillary phenomenon of the conductive bonding material D is suppressed, and a short circuit between the lead terminals is prevented.

Next, regarding a third embodiment of the present invention,
A description will be given with reference to the drawings, taking a surface mount type crystal vibration filter as an example. FIG. 5 is an exploded perspective view showing the third embodiment, and FIG. 6 is a plan view showing a state where the quartz vibrating plate of FIG. 5 is mounted. The same components as those in the first and second embodiments have been described using the same numbers.

The quartz vibrating plate 1 is formed of an AT-cut quartz vibrating plate and has a rectangular shape. Input / output electrodes (excitation electrodes) 13 and 14 are formed on the back surface, and extraction electrodes 13a and 14a for leading these input / output electrodes to both ends in the long side direction of the quartz plate are formed by means such as a vacuum evaporation method. It is formed. A ground electrode (excitation electrode) 1 is provided on the surface.
The extraction electrodes 15a and 15b for leading the ground electrode to both ends in the long side direction of the quartz vibrating plate are formed by means such as a vacuum evaporation method.

The package 2 has a rectangular parallelepiped shape with an open top as a whole, and includes a package base 20 made of ceramic as a bottom surface and a package peripheral wall 21 made as a wall surface.
And step portions 22 and 26 on which the quartz plate is mounted. The inner wall surface on which the step portion is formed has convex portions 211 and 217 formed at the centers of both ends in the long side direction, and the both end portions in the short side direction correspond to the short side width dimension of the piezoelectric vibration plate. The narrow part 212 with a part projected,
213, 218 and 219 are formed. The width between the narrow portions is formed to be slightly larger than the width in the short side direction of the quartz plate, and 1.05
Double to 1.15 times the width is preferred. If the ratio is smaller than the above-mentioned ratio, the insertion and positioning of the quartz plate into the package become difficult, and the workability is reduced. on the other hand,
If the ratio is larger than the above-mentioned ratio, the quartz vibrating plate is liable to be adversely affected by displacement and inclination in the short side direction. Also,
The electrode pads 221, 222, 2
61, 262, and a metal ring 2 made of Kovar or the like used for hermetic bonding is provided on the upper part of the peripheral wall 21.
3 are formed. The package 2 is integrally formed by firing using a ceramic lamination technique. The metal ring 23 is plated with a metal such as nickel.

Thereafter, the quartz vibrating plate 1 is connected to the step portions 22, 26.
And the lead-out electrode 13a and the electrode pad 22 are connected by a conductive bonding material D such as solder or conductive resin adhesive.
2. The extraction electrode 14a and the electrode pad 261, and the extraction electrodes 15a and 15b and the electrode pad 22.
1 and 262 are each electrically and mechanically joined. Then, although not shown, the metal lid and the metal ring 23 of the package are hermetically sealed by joining means such as seam welding. The hermetic sealing means may use a welding method such as an electron beam. Further, the crystal vibrating plate is not limited to the configuration for the crystal filter (the input / output electrodes are provided on one main surface and the ground electrode is provided on the other main surface of the front and back surfaces). (Excitation electrodes on each main surface of the front and back surfaces) may be adopted, and the extraction electrodes may be extended to both ends in the long side direction of the quartz plate. And the piezoelectric diaphragm is not only a quartz diaphragm, but also other piezoelectric single crystal plates,
A piezoelectric ceramic plate may be used. Further, the planar shape of the narrow portion is not limited to the rectangular shape as shown, but may be a semicircular shape, a semielliptical shape, or a triangular shape.

In the first embodiment of the present invention and the third embodiment of the present invention, as shown in the second embodiment, each step portion on which the quartz plate 1 is mounted is reduced to two. Alternatively, a groove may be formed between the electrode pads of each step. According to such a configuration, the surface distance between the electrode pads is increased, the capillary phenomenon of the conductive bonding material D (solder, conductive resin adhesive) is suppressed, and each electrode pad or lead terminal is provided. A short circuit between them can be further prevented. Further, as shown in the first embodiment of the present invention and the second embodiment of the present invention, when the quartz vibrating plate has a cantilever holding structure, the quartz vibrating plate has the narrow width as long as it does not affect vibration. By forming the length dimension of the portion in the long side direction to be large and securing a contact area with the quartz vibrating plate, it becomes difficult for the inclination to occur, so that the mounting accuracy of the quartz vibrating plate is improved.

[0025]

According to the first aspect of the present invention, the displacement and inclination of the piezoelectric vibrating plate in the short side direction are less likely to occur, so that the shock received on the package does not directly touch the piezoelectric vibrating plate.
Therefore, it is possible to prevent deterioration of the electrical characteristics such as cracking and chipping of the piezoelectric diaphragm.

In the piezoelectric vibrating plate, both ends in the short side direction of the piezoelectric vibrating plate are positioned with good balance in the gap, and the electrode pad formed in the step portion and the piezoelectric vibrating plate are positioned in the gap. The conductive bonding material that electrically and mechanically bonds to the diaphragm flows in, and the application state of the conductive bonding material can be recognized. Therefore, the amount of the conductive bonding material that electrically and mechanically connects the piezoelectric vibrating plate and the electrode pad is applied too much, or the applied amount of the conductive bonding material varies, resulting in a short circuit accident or CI. It is possible to prevent the electrical characteristics from deteriorating such as the value deteriorating. Also,
Deterioration of electrical characteristics such as deterioration of CI value and cracking of the conductive bonding material, which were caused by too little application amount of the conductive bonding material that electrically and mechanically connects the piezoelectric vibrating plate and the electrode pad. Is generated, and deterioration of mechanical characteristics such as detachment of the piezoelectric diaphragm can be prevented.

As described above, in the configuration in which the size of the piezoelectric vibration device is reduced and the piezoelectric vibration plate is easily mounted on the electrode pad in the package, the mounting position of the piezoelectric vibration plate and the confirmation of the application state of the conductive bonding material are described. It can be performed more accurately, and the reliability of the surface mount type piezoelectric vibration device can be improved.

According to the second aspect, in addition to the above functions and effects,
The protrusion on the inner wall surface restricts the conductive bonding material from flowing out in the gaps at both ends, and can prevent a short circuit between the electrodes led out only to one end in the long side direction.

According to the third aspect, when the solder is used as the conductive bonding material, the solder application state or the molten state of the solder is recognized, thereby preventing defective soldering such as staking, excessive solder flow, and insufficient solder. can do.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment according to the present invention.

FIG. 2 is a plan view of the configuration of FIG. 1 with a crystal diaphragm mounted.

FIG. 3 is an exploded perspective view showing a second embodiment according to the present invention.

FIG. 4 is a plan view of the configuration of FIG. 3 with a crystal diaphragm mounted.

FIG. 5 is a plan view showing a third embodiment according to the present invention.

FIG. 6 is a plan view showing a state in which a quartz plate is mounted in the configuration of FIG. 5;

[Explanation of symbols]

1, 3: quartz vibrating plate (piezoelectric vibrating plate) 2: package 22, 24, 25, 26: step portion 211, 214, 217: convex portion 212, 213, 215, 216, 218 , 219 ...
・ Narrow part D: Conductive bonding material (solder, conductive resin adhesive)

Claims (3)

(57) [Claims] 1. A package having a bottom surface and an inner wall surface for accommodating a piezoelectric vibrating plate, and a step portion on which at least one end in a long side direction of the piezoelectric vibrating plate is supported; A surface-mount type piezoelectric vibration device electrically connected to an electrode pad formed on the portion via a conductive bonding material, and a piezoelectric vibration plate having excitation electrodes formed on the front and back surfaces, wherein an inner wall surface of the step portion is provided. In the short side direction of the piezoelectric diaphragm
And the convex portion in contact with the central portion of the are and a narrow portion corresponding to the short side width of the piezoelectric vibrating plate is formed, the central portion of the short side of the piezoelectric vibrating plate, the narrow portion
Position so as to be located on the convex portion of the inner wall surface of the step portion.
-Decided tanning, the central portion of the short side of the piezoelectric vibrating plate, of the step portion
By contacting the protrusion on the side wall surface, the short-
A gap at the step is formed at both ends in the side direction, and the conductive bonding material flows into the gap at the step, and
A surface-mount type piezoelectric vibration device characterized in that the application state of an electrically conductive bonding material can be checked . 2. The surface-mounted piezoelectric vibration device according to claim 1, wherein the piezoelectric vibration plate has a one-sided electrical connection structure in which electrodes are led out only at one end in a long side direction. 3. The surface mount type piezoelectric vibration device according to claim 1, wherein the conductive bonding material is solder.