JP2008252442A - Manufacturing method for piezoelectric vibrating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a piezoelectric vibrating device capable of lowering a height without impairing joint strength between a cover body and a base. <P>SOLUTION: In a crystal oscillating piece 1, the crystal oscillating piece 3 is loaded on the inner bottom of the base 4 with an opening 9 and a bank 41 surrounding the opening 9 in an upper section, and the opening 9 is sealed and joined by the cover body 2. In the crystal oscillating piece 1, a metallic film 7 is formed on the top face of the bank section 41 in a peripheral shape, and a solder material S is formed at a place adjoined to the inner wall 8 of the bank section in the peripheral shape on the sealing joining surface of the cover body 2 in a state of superposing the cover body 2 to the opening 9. The solder material S forms a fillet by heating and melting, and the cover body 2 and the base 4 are joined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a piezoelectric vibration device used in electronic equipment and the like.

Quartz resonators are widely used as piezoelectric vibration devices used in electronic devices, etc.
The surface-mount type crystal resonator is a crystal resonator having a form corresponding to the demand for low profile and space saving.

  As shown in FIG. 9, the conventional surface-mount type crystal resonator has a rectangular shape in plan view having an opening 9 in the upper portion and a crystal vibrating piece 3 in a container body (hereinafter referred to as a base) 4 made of an insulating material. It has a structure formed by housing and joining the opening 9 with a lid 2 having a rectangular shape in plan view made of metal. Here, a circumferential bank 41 surrounding the opening 9 is formed on the base 4, and a metal film 7 is circumferentially formed on the upper surface of the bank 41. Further, a brazing material S is formed as a sealing bonding material on the sealing bonding surface (sealing bonding surface with the base) of the lid body 2, and the lid body 2 is mounted on the metal film 7 of the base 4. Then, the base 4 and the lid 2 are hermetically sealed by melting the brazing material S in a heated atmosphere.

  However, with the recent miniaturization of crystal resonators, the joint region between the base and the lid is narrowed, making stable hermetic sealing difficult. In order to solve such a problem, the metal film formed only on the upper surface of the bank is formed to extend to the inner wall of the bank, and the lid is sealed from the metal film formed on the inner wall. For example, Patent Literature 1 discloses a piezoelectric vibration device having a configuration in which a lid and a base are firmly bonded by forming a fillet of the bonding material toward the bonding surface.

JP 2005-347851 A

  However, in Patent Document 1, it is difficult to reduce the height of the piezoelectric vibrator device due to the thickness of the bonding material existing between the metal film on the upper surface of the bank portion and the lid.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a piezoelectric vibration device that can achieve a low profile without impairing the bonding strength between the lid and the base. It is.

  In order to achieve the above object, the invention according to claim 1 is provided with a rectangular base in plan view having an opening at the top, a bank portion surrounding the opening, and a piezoelectric vibrating piece at the inner bottom of the base. In the piezoelectric vibration device obtained by sealing and joining the opening with a rectangular lid in plan view, a metal film is formed on the upper surface of the bank portion in a circumferential shape, and the opening is In the state where the lid is overlapped, a brazing material is formed in a circumferential shape on the sealing joint surface of the lid at a position close to the inner wall of the bank portion, and is heated and melted to fillet the brazing material. The lid body and the base are joined together to form a piezoelectric vibration device, and the molten brazing material is unlikely to intervene on the surface of the metal film on the upper surface of the bank portion during the heating and melting. Because of the low piezoelectric vibration device It is possible to achieve the reduction.

  According to the above configuration, since the brazing material is circumferentially formed at a position close to the inner wall of the bank portion on the sealing joint surface of the lid body, the lid body is overlaid on the base opening portion. Sometimes, the brazing material does not contact the upper part of the metal film formed on the upper surface of the bank portion. Due to the relative positional relationship between the metal film and the brazing material, the brazing material melted by heating hardly flows into the gap between the metal film on the top surface of the bank and the lid.

  In the present invention, the sealing joint between the lid and the base is mainly performed by the fillet of the brazing material, but a sufficient brazing material is interposed between the lid and the upper surface of the bank portion as in the prior art. Even if it is not, practical joint strength can be obtained. At the same time, since the thickness of the bonding material can be reduced, the height of the crystal unit can be reduced.

  Further, according to the above configuration, since the brazing material is circumferentially formed on the sealing joint surface of the lid body at a position close to the inner wall of the bank portion, the inner peripheral side surface of the metal film is heated and melted. A fillet is formed between the part and the brazing material, ensuring bonding strength even when there is no brazing material between the metal film on the top of the bank and the lid, or when there is a slight brazing material can do.

  In the above configuration, the brazing material on the sealing joint surface of the lid is overlaid in the state of being close to the inner wall. In other words, the lid is in a state of being fitted into the opening of the base. The term “fitting” as used herein includes a state in which a minute space exists between the inner wall and the brazing material, and a state in which the inner wall and the brazing material are in contact with each other.

  Further, since the brazing material is formed on the inner side separated from the periphery of the lid body as described above, positioning (when details will be described later) on the lid body with the opening of the base 4 facing downward (details will be described later) It has a function of a guide) and can suppress displacement of the lid relative to the base.

  Furthermore, in the case of the above-described configuration, the brazing material is circumferentially positioned not at the peripheral edge portion of the sealing joint surface of the lid body but at a position close to the inner wall of the bank portion, that is, a position spaced inward from the peripheral edge of the lid body. Since it is formed, the circumferential length of the brazing material is shorter than in the prior art, so that the amount of brazing material used is reduced, and there is a cost reduction effect.

  In the above configuration, the brazing material is formed in a circumferential shape at a position close to the inner wall of the bank portion on the sealing joint surface of the lid, but is not limited thereto.

  For example, first, a brazing material is formed on the surface of the lid body from the periphery to the inner region of the lid body (first brazing material), and the upper portion is close to the inner wall of the bank portion. That is, a configuration in which a brazing material (second brazing material) is laminated in a circumferential shape at a position spaced inward from the peripheral edge of the lid may be employed.

  In this case, the surface of the metal film on the top surface of the bank portion and the first brazing material are joined, and the inner peripheral side surface portion of the metal film and the second brazing material are joined, A stronger bonding force can be obtained. In addition, it is preferable from the point of height reduction that the thickness of the said 1st brazing material is formed thinner than the case where only 1 layer of brazing materials is formed like the past.

  According to a second aspect of the present invention, there is provided a method for manufacturing a piezoelectric vibration device, wherein the metal film extends from an upper surface of the bank portion to an inner wall of the bank portion, and in this case, a lid body A fillet of brazing material is formed from the sealing joint surface to the metal film extending to the inner wall of the bank. With such a configuration, since the deposition area can be made wider than that of the conventional crystal resonator, the bonding strength is improved. Therefore, even if no bonding material is formed in the peripheral region of the sealing bonding surface of the lid, practical bonding strength can be ensured and the height can be reduced.

  Furthermore, according to claim 3, in the center of at least two opposing sides among the four opposing sides of the rectangle formed by the inner peripheral edge of the bank portion, the metal film is from the upper surface of the bank portion. A method of manufacturing a piezoelectric vibration device characterized in that it is formed to extend to the inner wall of the bank, and in this case, the metal film extends from the upper surface of the bank to the inner wall of the bank. , It is partly formed rather than circumferential.

  Here, when the lid body and the base are joined by heating and melting via a brazing material, the molten brazing material has fluidity, so that four rectangular corner portions formed on the upper surface of the bank portion There is a tendency that brazing material flows into (corner portion) and tends to stay (“dense” state), and conversely, the central portion of each side of the rectangle has a small amount of brazing material due to outflow to the corner portion ( Since there is a tendency to be “thin” (“sparse” state), there is a concern that the joint strength of the central portion of each side in the “sparse” state is lower than that of the corner portion.

  On the other hand, the metal film extends from the top surface of the bank portion to the inner wall of the bank portion at the center of at least two of the four opposing sides of the rectangle as in the above configuration. If formed, the joint strength can be supplemented by forming a braze fillet from the sealing joint surface of the lid to the metal film extending to the inner wall of the bank portion at the center of each side. Therefore, the bonding strength of the entire crystal unit can be improved. In particular, the effect can be expected if the metal film is formed so as to extend at the center of all the four sides.

  In the above configuration, when the metal film is formed only at the center of the two opposing sides of the rectangle, the longer side having a larger area, that is, the center of the two opposing long sides is formed. Is preferable because it has a great influence on the bonding strength.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a piezoelectric vibration device that can reduce the height without reducing the bonding strength between the lid and the base.

(First embodiment)
Hereinafter, a first embodiment according to the present invention will be described with reference to FIGS. 1 and 2, taking a surface-mounted crystal resonator as an example. FIG. 1 is a cross-sectional view in the long side direction of the crystal unit after sealing showing the first embodiment of the present invention, and FIG. 2 is a cross-sectional view in the long side direction of the crystal unit showing the state before sealing in FIG. FIG. 1 and 2, electrodes (described later) formed on the front and back surfaces of the quartz crystal vibrating piece, external connection terminals formed on the base bottom surface (back surface), the external connection terminals, and mounting pads inside the base The description of the wiring conductor that electrically connects is omitted.

  As shown in FIG. 1, the crystal resonator 1 applied in the present embodiment is composed of a lid body 2 having a rectangular shape in plan view, a cuboid crystal vibrating piece 3, and a base 4 having a rectangular shape in plan view. Yes.

  In FIG. 1, the quartz crystal vibrating piece 3 is an AT-cut quartz plate having a rectangular shape in plan view, and an excitation electrode (not shown) for driving the quartz crystal vibrating piece 3 is drawn on the front and back surfaces, and is drawn from the excitation electrode. A lead electrode (not shown) and a pair of pad electrodes (not shown) connected to the lead electrode and formed on both sides of one end of the crystal vibrating piece 3 are formed. These electrodes are formed on the quartz in order from the bottom in the form of chromium (Cr), gold (Au), and chromium (Cr) by vapor deposition. The film configuration of the electrode is not limited to this, and other film configurations may be used.

  In FIG. 1, a base 4 is formed by laminating a plurality of ceramic green sheets made of an alumina ceramic material and firing them integrally. The base 4 has an opening 9 for accommodating the crystal vibrating piece 3 in the upper part, and includes an annular bank 41 around the opening 9.

  In FIG. 1, a pair of mounting pads 5 are formed in parallel on one end side of the inner bottom portion of the base 4. The mounting pad 5 is subjected to gold plating on the surface after printing and baking tungsten. The mounting pad 5 is electrically connected to an external connection terminal (not shown) formed on the bottom surface (back surface) of the base via a wiring conductor (not shown) formed inside the base. . The electrical connection between the mounting pad 5 and the external connection terminal may be performed by forming castellations at the four corners of the upper and lower outer periphery of the base 4.

  The top surface of the bank portion 41 of the base 1 is flat, and a circumferential metal film 7 is formed on the top surface of the bank portion. The metal film 7 is composed of three layers, and is laminated from the bottom in the order of tungsten, nickel, and gold. Tungsten is integrally formed during ceramic firing by metallization technology, and the nickel and gold layers are formed by plating technology. Note that molybdenum may be used for the tungsten layer.

  In FIG. 1, a lid body 2 is formed of a metal material having a rectangular shape in plan view. In this embodiment, the lid body 2 has a nickel plating layer as an upper layer and a gold flash plating layer as an upper layer around the entire circumference. Is formed. Here, the thickness of each layer is 1.0 to 4.0 μm for the nickel layer and about 0.01 μm for the gold flash layer. The gold flash layer is preferably formed with a thickness of 0.03 μm or less.

  As shown in FIG. 2, on the sealing joint surface side of the lid body 2, an inner side of a virtual line L in which the metal brazing material S extends upward along the bank wall 8 on the gold flash plating layer. It is formed in a circumferential shape in the region. In this embodiment, a gold-tin alloy (Au—Sn alloy) is used as the brazing material. Here, the Au—Sn alloy includes the gold constituting the entire crystal unit, that is, the gold flash plating layer formed on the lid 2 and the metal film 7 formed on the upper surface of the bank portion in the melted state. Thus, the composition of the Au—Sn alloy formed on the sealing joint surface of the lid 2 is adjusted in advance so that the ratio of Au: Sn = 80: 20.

  In the present embodiment, a pair of pad electrodes formed on both sides of one end portion of the crystal vibrating piece 3 and a pair of mounting pads 5 on the inner bottom portion of the base 4 are bonded via the conductive bonding material 6. . As the conductive bonding material, for example, a silicone-based conductive resin bonding material is used. The conductive bonding material is not limited to the silicone-based conductive resin bonding material, and an epoxy-based conductive resin bonding material may be used in addition to the silicone-based bonding material.

  The crystal vibrating piece 3 and the mounting pad 5 are bonded by the conductive resin bonding material by curing the conductive bonding material 6 in an atmosphere controlled to a predetermined temperature profile.

  After the pad electrode and the mounting pad 5 are joined, the lid body 2 is placed in a sealing jig. The sealing jig has a concave portion inside, and is placed in the concave portion with the sealing joint surface side of the lid body 2 facing up. Then, the base 4 is placed on the lid 2 with the opening 9 facing downward. At this time, the circumferential brazing material S formed on the sealing joint surface side of the lid body 2 is accommodated in the opening 9, and the upper surface of the bank portion of the base 4 is the sealing joint surface of the lid body 2. In this state, the brazing material S is in contact with the peripheral area where the brazing material S is not formed. In this state, the brazing material S formed on the lid 2 is melted by heating to a predetermined temperature. The molten brazing material is hermetically bonded by forming a fillet of brazing material from the sealing joint surface of the lid to the inner peripheral side surface portion of the metal film. The surface-mounted crystal resonator 1 is completed through the above steps.

  As described above, the brazing material S is formed in a circumferential shape in the region inside the virtual line L extending upward along the bank wall 8 on the sealing joint surface of the lid 2. When the base 4 is placed on the lid body 2, the brazing material S is fitted in a state close to the inner wall 8 of the bank portion, and on the upper part of the metal film formed on the upper surface of the bank portion 41. The brazing material S does not contact. With such a structure, the brazing material S is unlikely to intervene on the upper surface of the bank portion 41, so that the height of the crystal unit can be reduced.

(Modification of the first embodiment)
A modification in the present embodiment will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the crystal resonator in the long side direction before sealing showing a modification of the first embodiment, and FIG. 4 is a modification of the first embodiment, showing crystal vibration showing a state after sealing. It is sectional drawing of the long side direction of a child. In addition, about the structure similar to the above-mentioned embodiment, while attaching | subjecting the same number and omitting a part of description, it has an effect similar to the above-mentioned embodiment.

  In FIG. 3, a first brazing material S <b> 1 is formed on the sealing joint surface side of the lid body 2 from the periphery of the lid body to the inner region, and the inner wall of the bank portion is formed on the upper layer thereof. The second brazing material S2 is located in a region inside the imaginary line L extending upward along the line 8, that is, a position that is spaced inward from the periphery of the lid and does not deviate from the first brazing material S1. It is formed in a circumferential shape. Here, the first and second brazing materials S1, S2 are metal brazing materials of the same material. Thereby, a thin area and a thick area of the brazing material S are formed, and the thick area is close to the inner wall 8 of the bank portion.

  Then, when the lid body 2 and the base 4 are joined by heating and melting the first and second brazing materials S1 and S2, the state shown in FIG. 4 is obtained. As shown in FIG. 4, the fillet of the second brazing material S2 is formed from the sealing joint surface of the lid body 2 to the inner peripheral side surface portion of the metal film 7 formed on the upper surface of the bank portion 41, The upper surface of the metal film 7 and the first brazing material S1 are joined. In this case, since the thickness of the first brazing material S1 is thinner than the thickness of the conventional brazing material S having a single-layer structure, it contributes to a reduction in height and is joined by the two brazing materials S1 and S2. As a result, the bonding strength is improved.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional view in the long side direction of the crystal resonator after sealing showing a modification of the second embodiment, and FIG. 6 is the long side direction of the crystal resonator after sealing in the second embodiment. It is sectional drawing. In addition, about the structure similar to the above-mentioned embodiment, while attaching | subjecting the same number and omitting a part of description, it has an effect similar to the above-mentioned embodiment.

  As shown in FIG. 5, the metal film 7 formed on the upper surface of the bank portion 41 is formed to extend to the bank wall 8. On the other hand, on the sealing joint surface of the lid body 2, the brazing material S is placed in a position away from the peripheral edge of the lid body 2, that is, in a region inside the virtual line L extending upward along the bank inner wall 8. Is formed in a circumferential shape.

  FIG. 6 shows a state in which the brazing material S is heated and melted and the lid 2 and the base 4 are joined. As shown in FIG. 6, since the fillet of the brazing material S is formed from the lid sealing joint surface to the metal film 7 formed on the inner wall 8 of the bank portion, it is attached more than the conventional crystal resonator (FIG. 9). A large area can be taken. As a result, the bonding strength is improved, and the brazing material is not formed in the peripheral region of the sealing bonding surface of the lid 2, so that the height of the crystal unit can be reduced.

(Modification of the second embodiment)
A modification in the present embodiment will be described with reference to FIG. FIG. 7 is a perspective view of a base showing a modification of the second embodiment, in which the metal film 7 formed in a circumferential shape on the upper surface of the bank portion 41 has four inner walls facing the inner circumference of the bank portion 41. The state extended only to the center part of is shown. In addition, about the structure similar to the above-mentioned embodiment, while attaching | subjecting the same number and omitting a part of description, it has an effect similar to the above-mentioned embodiment.

  In the conventional crystal unit structure, when the lid and the base are joined by heating and melting through a brazing material, four rectangular corner portions (corner portions) in which the molten brazing material is formed on the upper surface of the bank portion are formed. ) Tends to easily flow in and stay (“dense” state), and conversely, the central part of each side of the rectangle is reduced (thinned) by the outflow to the corner. (“Sparse” state). For this reason, there has been a concern that the bonding strength of the central portion of each side in a “sparse” state is lower than that of the corner portion.

  On the other hand, if the metal film 7 is formed to extend from the upper surface of the bank 41 to the bank wall 8 at the center of the four opposing sides of the rectangle as shown in FIG. The center portion of the rectangular shape is formed by forming a fillet of the brazing material S from the sealing joint surface of the lid body 2 to the metal film 7 formed on the inner wall 8 of the bank portion, so that the central region of the four opposing sides of the rectangle is formed. The bonding strength can be supplemented, and the bonding strength of the crystal unit 1 can be improved.

  In the present invention, the metal film 7 formed on the bank inner wall 8 is in a state of being embedded in the inner wall, but is not limited to this form, and as shown in FIG. It may be formed on the bank wall 8. The brazing material S formed on the sealing joint surface of the lid body 2 is formed in a circumferential shape in a region inside the virtual line L extending upward along the surface of the metal film 7. Here, the metal film 7 extended to the inner wall 8 of the bank and the brazing material S are formed in close proximity.

  In the embodiment of the present invention, a gold-tin alloy (Au—Sn alloy) is used as the brazing material, but the present invention is not limited to this. For example, a tin-silver alloy (Sn—Ag alloy), Other metals such as gold-germanium (Au—Ge alloy) may be used.

  In the embodiment of the present invention, the individual lid and the individual base are configured to be sealed and joined. However, the present invention is not limited to this, and a plurality of bases are integrally arranged in a matrix. The present invention can also be applied to a configuration in which the opening of each base of the mother board is sealed and joined to the base in the state, that is, the mother board with the individual lid.

  In the embodiment of the present invention, a surface-mount type crystal resonator is taken as an example, but the present invention can also be applied to a method for manufacturing other surface-mount type piezoelectric vibration devices used for electronic devices such as a crystal filter and a crystal oscillator.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to mass production of piezoelectric vibration devices.

1 is a longitudinal sectional view of a crystal resonator showing a first embodiment of the present invention. FIG. 2 is a cross-sectional view in the long side direction of a crystal resonator showing a state before sealing in FIG. 1. FIG. 6 is a cross-sectional view in the long side direction of a crystal resonator before sealing, showing a modification of the first embodiment. FIG. 7 is a cross-sectional view in the long side direction of a crystal resonator after sealing, showing a modification of the first embodiment. Sectional drawing of the long side direction of the crystal oscillator before sealing which shows 2nd Embodiment. FIG. 6 is a cross-sectional view in the long side direction of a crystal resonator after sealing, showing a second embodiment. The perspective view of the base which shows the modification of 2nd Embodiment. FIG. 9 is a cross-sectional view in the long side direction of a crystal resonator before sealing showing a modification of the second embodiment. The long side direction sectional view showing the example of the conventional crystal oscillator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crystal oscillator 2 Cover body 3 Crystal vibrating piece 4 Base 5 Mounting pad 6 Conductive joining material 7 Metal film 8 Inner wall inner wall 9 Opening part 41 Embankment S Brazing material S1 1st brazing material S2 2nd brazing material

Claims (3)

A rectangular base in plan view having an opening at the top and a bank portion surrounding the opening, and a piezoelectric vibrating piece are mounted on the inner bottom of the base, and the opening is sealed with a rectangular lid in plan view. In a piezoelectric vibration device obtained by stop bonding,
A metal film is circumferentially formed on the top surface of the bank portion, and in a state where the lid body is overlaid on the opening, the sealing joint surface of the lid body is formed on the inner wall of the bank portion. A method of manufacturing a piezoelectric vibration device, wherein a brazing material is formed in a circumferential shape in an adjacent position, a fillet of the brazing material is formed by heating and melting, and the lid and the base are joined.   The method for manufacturing a piezoelectric vibration device according to claim 1, wherein the metal film extends from an upper surface of the bank portion to an inner wall of the bank portion.   The metal film extends from the upper surface of the bank portion to the inner wall of the bank portion at the center of at least two of the four opposing sides of the rectangle formed by the inner peripheral edge of the bank portion. The method for manufacturing a piezoelectric vibration device according to claim 1, wherein the piezoelectric vibration device is formed.

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