JP2011205391A - Electronic component package, and piezoelectric vibration device employing the electronic component package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration device which is correspondent to reduction in size and reduction in height and stabilizes characteristics.SOLUTION: A surface mounted crystal vibration device is comprised of: a base 1 having a recess whose upper portion is opened; a crystal diaphragm 2 that is a piezoelectric diaphragm accommodated in the base; and a lid 3 joined to the opening of a package. A cavity of the base 1 is configured to have a lower cavity 1b and an upper cavity 1a and a step 1c is formed in a part of the lower cavity 1b. A lower cavity inner wall 10b rises from an inner bottom face 111 of the base at an angle of 45° (inner wall angle θ1). Furthermore, an upper cavity inner wall 10a rises at an angle of 75° (inner wall angle) with respect to a surface in parallel with the inner bottom face of the base.

Description

  The present invention relates to a package for electronic components and a piezoelectric vibration device used for electronic equipment and the like.

  The cavity (internal space) of the electronic component package is hermetically sealed in order to prevent deterioration of the characteristics of the electronic component element housed in the cavity and to obtain stable characteristics. As an example of such a configuration, a crystal resonator or a crystal oscillator using a crystal resonator element as an electronic component element can be given.

  Specifically, from a base having a bottom and side walls and having an opening to form a cavity, a crystal resonator element housed in the cavity of the base, and a lid for hermetically sealing the crystal resonator element It is the composition which becomes. (See Patent Document 1)

JP 2002-151994

  Due to the recent downsizing and reduction in height of electronic components, the problem of reduced mechanical strength has become apparent with respect to a base provided with a cavity. That is, the thickness of the bottom surface of the package, that is, the thickness of the inner bottom surface of the cavity and the outer bottom surface of the outer side of the base, and the thickness of the side wall, that is, the thickness of the inner wall surface of the cavity and the outer wall surface of the outer side of the base are reduced. One or both of them became thin, and a failure in a failure mode such as a crack sometimes occurred in the base. In particular, such a destructive mode may occur at a bent portion that becomes a boundary between the inner bottom surface of the package and the inner wall surface. In such a case, the quality and reliability of the electronic component are reduced due to a decrease in airtightness.

  Further, when the thickness of the bottom surface or the side wall is increased in order to improve the package strength, the volume of the cavity is limited, and the external size of the electronic component element that can be stored may be limited. For example, in the case of a crystal resonator element, the external size of the crystal resonator element may be increased by design depending on the required specifications. In such a case, it is difficult to store the crystal resonator element in the cavity with a limited volume. In some cases, the characteristics as a desired electronic component cannot be obtained with a limited package size such as a limited size.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electronic component package that improves the strength of the electronic component package and contributes to improved characteristics.

  It is another object of the present invention to provide a piezoelectric vibration device that can be reduced in size and height and has stable characteristics.

  The present invention has been made to achieve the above object, and as described in claim 1, has a cavity for housing an electronic component element on which an electrode is formed, and is electrically connected to the electrode. An electronic component package having a base having an external connection terminal and a lid for hermetically sealing the cavity, the cavity having an upper cavity and a lower cavity located below the upper cavity, The inner wall angle of the lower cavity is smaller than the inner wall angle of the upper cavity.

  The cavity may have a configuration in which the inner wall angle of the lower cavity is smaller than the inner wall angle of the upper cavity, and may have a plurality of upper cavities having a plurality of inner wall angles above the lower cavity. The inner wall angle indicates the angle (θ1 and θ2) of the inner wall rising from the inner bottom surface of the base or a surface parallel to the inner bottom surface.

  According to claim 1, the cavity has an upper cavity and a lower cavity located below the upper cavity, and the inner wall angle of the lower cavity is smaller than the inner wall angle of the upper cavity, so that the inner bottom portion of the base The angle of the bent portion formed by the inner wall of the lower cavity can be increased to make it an obtuse angle. As a result, it is possible to suppress the occurrence of breakage from the bent portion, which was the starting point of the breakage mode such as a crack in the past.

In addition, the inner wall angle of the upper cavity is larger than the inner wall angle of the lower cavity, so the thickness of the side wall of the upper part of the base does not become too thin, ensuring package strength and expanding the volume of the upper cavity. And a sufficient storage space for the electronic component element can be secured.

According to a second aspect of the present invention, there is provided the electronic component package characterized in that an inner wall angle of the lower cavity is in a range of 35 degrees to 50 degrees.

By setting the inner wall angle of the lower cavity in the range of 35 degrees to 50 degrees, the angle of the bent portion formed by the inner bottom of the base and the inner wall of the lower cavity can be an obtuse angle of 130 degrees to 145 degrees. The occurrence of destruction from the part can be suppressed. If the inner wall angle is 35 degrees or less, the thickness of the bank portion may be too thin and the strength of the package may be reduced. If the inner wall angle is 50 degrees or more, the inner wall is formed by the inner bottom surface and the inner wall of the lower cavity. As a result, the angle of the bent portion of 1 becomes small, which tends to be a starting point of crack generation in the base, resulting in a reduction in the strength of the package.

According to a third aspect of the present invention, in the electronic component package according to the third aspect, the inner wall angle of the upper cavity is in the range of 60 degrees to 85 degrees.

  By setting the inner wall angle of the upper cavity in the range of 60 to 85 degrees, a sufficient thickness of the side wall can be secured even at the upper end portion of the upper cavity following the inner wall of the lower cavity, and the strength of the base can be increased. A practical cavity volume can be secured without being lowered. As described above, the electronic component element can be accommodated without being limited as much as possible by the package volume. If the inner wall angle is 60 degrees or less, the thickness of the bank portion may be too thin and the strength of the package may be reduced. If the inner wall angle is 85 degrees or more, the inner wall is formed by the lower cavity inner wall and the upper cavity inner wall. The angle of the second bent part becomes small, and it tends to be a starting point of crack generation in the base, leading to a decrease in the strength of the package. Further, since the volume of the upper cavity is reduced, the size of the electronic component element is limited, and desired characteristics as an electronic component may not be obtained.

  Further, the piezoelectric vibration device is characterized in that the electronic component element is a piezoelectric vibration element in which an excitation electrode is formed, and the piezoelectric vibration element is disposed in the upper cavity. May be.

With the above configuration, since the piezoelectric vibration element can be arranged in a wide space of the upper cavity, the piezoelectric vibration element can be accommodated without being limited by the package volume as much as possible, and has a stable characteristic and high reliability. A vibrating device can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the intensity | strength of the package for electronic components can be improved, and the package for electronic components which contributes to a characteristic improvement can be obtained.

  Further, according to the present invention, it is possible to obtain a piezoelectric vibration device that can cope with a reduction in size and height and has stable characteristics.

The top view of the base used for 1st Embodiment by this invention The exploded view which shows the internal structure of the piezoelectric vibration device which shows 1st Embodiment by this invention The internal structure figure of the piezoelectric vibration device which shows 1st Embodiment by this invention The figure explaining the piezoelectric vibration device manufacturing process by this invention The figure explaining the piezoelectric vibration device manufacturing process by this invention The figure explaining the piezoelectric vibration device manufacturing process by this invention The figure explaining the piezoelectric vibration device manufacturing process by this invention The figure explaining the piezoelectric vibration device manufacturing process by this invention

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIGS. 1 to 4 by taking a surface-mount type crystal vibrating device as an example. FIG. 1 is a plan view of a base used in this embodiment, FIG. 2 is an exploded view showing an internal structure using the base of FIG. 1, and the base shows a cross section taken along line AA of FIG. Yes. FIG. 3 is an internal structure diagram in a state where the configuration shown in FIG. 2 is assembled, and FIGS. 4 to 8 are diagrams showing a manufacturing process of the piezoelectric vibration device.

The surface-mount type crystal vibrating device includes a base 1 having a recess having an upper opening, a crystal vibrating plate 2 that is a piezoelectric vibrating plate housed in the base, and a lid 3 joined to an opening of the package. Become.

  The base 1 as a whole has a rectangular parallelepiped shape, a box shape having an opening at the top, a bottom portion 11, a bank portion 10, and a step portion 1c, and a generally concave cavity as viewed in cross section. is there. In the present embodiment, the base has a configuration in which a conductive electrode made of a metal film is formed on the inside and outside using borosilicate glass as a base.

The bottom portion 11 has an inner bottom surface 111 on the cavity side and an outer bottom surface 112 on the outer side of the base. The step portion 1c has a configuration in which a part of the inner bottom portion 111 is raised by one step, and in the present embodiment, the step portion 1c is formed so as to be biased toward one end portion of the base long side. The step portion 1 c is provided with a pair of electrode pads 12, 13. The electrode pads 12, 13 are drawn to the inner bottom surface 111 below the step portion by connecting electrodes 12 a, 13 a and connected to the vias 14, 15. Yes. The vias 14 and 15 have through-holes 11a and 11b formed above and below the bottom part 11, and the through-holes 11a and 11b are filled with a metal material made of, for example, a tin alloy of gold tin (AuSn) layer or copper. And externally connected to the external connection terminals 16 and 17 formed on the outer bottom surface 112, respectively. Each of the through holes 11a and 11b has a conical shape, and the opening gradually expands from the inner bottom portion 111 toward the outer bottom portion 112. The through hole may be configured such that the opening gradually widens from the outer bottom portion 112 toward the inner bottom portion 111, or may be configured such that the width decreases from both sides of the bottom portion toward the central portion in the thickness direction of the bottom portion. The configuration may be a configuration in which the cross section is rectangular or a configuration in which the cross section is a drum shape (a configuration in which the inner wall gradually expands and the inner wall has a substantially parallel region).

The cavity of the base 1 has a lower cavity 1b and an upper cavity 1a, and a step 1c is formed in a part of the lower cavity 1b. The upper surface of the step 1c is a surface that separates the upper cavity and the lower cavity. The upper surface of the stepped portion 1c is a flat surface, and the electrode pads 12 and 13 are provided at a predetermined interval as described above.

The bank portion 10 is formed so as to extend upward from the outer periphery of the bottom portion 11, thereby forming a cavity, and an inner wall is formed inside the cavity. An upper cavity inner wall 10a is formed in the upper cavity 1a, a lower cavity inner wall 10b is formed in the lower cavity 1b, and a first bent portion 10c is provided at the boundary between the inner bottom surface 111 and the lower cavity inner wall 10b. The upper cavity inner wall 10a and the lower cavity inner wall 10b are connected by a second bent portion 10d.

The lower cavity inner wall 10b rises from the inner bottom surface 111 of the base at an angle of 45 degrees (inner wall angle θ1). The inner wall angle θ1 is preferably in the range of 35 degrees to 50 degrees. In such a range, the angle of the first bent portion 10c formed by the inner bottom surface of the base and the inner wall of the lower cavity can be an obtuse angle of 130 to 145 degrees, and the base from the first bent portion can be formed. Can be prevented from breaking. If the inner wall angle θ1 is 35 degrees or less, the thickness of the bank portion may be too thin, resulting in a decrease in package strength. If the inner wall angle θ1 is 50 degrees or more, the inner wall angle θ1 is formed by the inner bottom surface and the inner wall of the lower cavity. The angle of the first bent part becomes small, and it tends to be a starting point of crack generation in the base, leading to a reduction in the strength of the package.

The upper cavity inner wall 10a rises at an angle of 75 degrees (inner wall angle) with respect to a plane parallel to the inner bottom surface of the base. The inner wall angle is preferably in the range of 60 to 85 degrees. Within such a range, the side wall thickness of the inner wall of the upper cavity can be sufficiently secured, the strength of the base is not lowered, and a practical cavity volume can be secured. If the inner wall angle θ2 is 60 degrees or less, the thickness of the bank portion may be too thin, and the strength of the package may be reduced. If the inner wall angle θ2 is 85 degrees or more, the inner wall of the lower cavity and the inner wall of the upper cavity may be reduced. The angle of the second bent portion to be formed becomes small, and it tends to be a starting point of crack generation in the base, leading to a reduction in package strength. Further, since the volume of the upper cavity is reduced, the size of the electronic component element is limited, and desired characteristics as an electronic component may not be obtained.

In addition, a metal layer 101 is formed on the upper surface of the bank portion 10 formed in a circumferential shape on the base, and the metal layer 101 becomes a region to be hermetically bonded to a lid described later.

The quartz crystal plate 2 is an AT cut quartz plate and has a rectangular shape in plan view and has a long side and a short side. Excitation electrodes 21 and 22 are formed on the front and back of the central portion of the main surface of the crystal diaphragm 2. The excitation electrodes 21 and 22 have a rectangular shape in a plan view and are similar to a crystal diaphragm, and have long sides and short sides. In the respective excitation electrodes 21 and 22 on the front and back sides, extraction electrodes 21a and 22a are drawn from the short side of one excitation electrode to the short side of one crystal diaphragm. In addition to the AT-cut quartz diaphragm, a tuning fork type quartz diaphragm or other piezoelectric diaphragm may be used.

The excitation electrode and the extraction electrode are made of a metal film. For example, the excitation electrode and the extraction electrode have a two-layer structure in which a chromium film is formed as a base layer in contact with a quartz diaphragm and a gold film is formed as an upper layer on the chromium film. The metal film configuration may be other metal materials, for example, a titanium film or a nickel film may be used for the underlayer. Alternatively, a material such as a silver film or a copper film, or an alloy film of a gold alloy, a silver alloy, or a copper alloy may be used for the upper layer.

The electrode-formed quartz diaphragm is cantilevered on the electrode pads 12 and 13 using a conductive bonding material S. As the conductive bonding material S, a resin adhesive containing lead-free solder or conductive filler is used.

The lid 3 is made of a glass plate having a rectangular shape in plan view. As the material of the glass plate, for example, borosilicate glass is used, and the glass plate has a belt-like metal brazing material formed in a circumferential shape in a portion corresponding to the metal film 101 of the base. The metal brazing material is made of a tin alloy such as a gold-tin alloy or a copper-tin alloy, and is formed using a technique such as plating.

By joining the base 1 and the lid 3 with the metal brazing material, the quartz diaphragm 2 housed inside is hermetically housed, but the inside atmosphere is an inert gas such as nitrogen gas or a vacuum atmosphere. . In this embodiment, a vacuum atmosphere is used.

Next, a method for forming the outer shape of the base used in this embodiment will be described with reference to FIGS. 4 to 8 show a manufacturing process for a part of the glass wafer. As shown in FIG. 4, first, a glass wafer W1 using borosilicate glass such as Pyrex (registered trademark) glass is prepared, and a patterned metal film is formed on the surface (one main surface) of the glass wafer W1. Specifically, a chromium film is formed on the front and back surfaces of the glass wafer W1 by a vacuum deposition method or a sputtering method, and a gold film is similarly formed on the upper surface by a vacuum deposition method or a sputtering method. A resist film is formed on the upper surface (both front and back surfaces) of the metal film having such a configuration. The resist film is formed using a spin coating method or the like. Next, the resist film on the surface side is exposed to light using a predetermined photomask to obtain a patterned resist film on the surface side of the glass wafer. The metal film is etched using the resist film as a mask to obtain a patterned metal film M and a patterned resist film R as shown in FIG.

Next, as shown in FIG. 5, the glass wafer is etched using the patterned resist film R and metal film M. The etching is performed in the thickness direction of the glass wafer by wet etching E1. Specifically, a glass wafer masked with a resist film and a metal film is immersed in an etchant and etched in the thickness direction. However, in this embodiment mode, wet etching is performed on the isotropic material, so that etching proceeds in the lateral direction in addition to the thickness direction. Therefore, the inner wall angle of about 45 degrees is obtained by etching with the wall surface tapered.

Next, as shown in FIG. 6, a metal layer 101 is formed in a portion corresponding to the bank portion of the base. Specifically, the resist film R shown in FIG. 5 is removed to form a new patterned resist film (not shown). Using this newly patterned resist film as a mask, a part of the metal film M is etched to form a metal film M corresponding to the metal layer on the bank portion of the base. Then, metal plating is performed on the upper surface of the metal film to form a metal layer 101 on the wafer front side and a metal layer 102 on the wafer back side.

Then, as shown in FIG. 7, a cavity having an upper cavity and a lower cavity is formed. Specifically, the metal layer in the through hole forming region is removed in advance from the metal layer 102 using a photolithography technique. As a result, the metal layers 101 and 102 in which the cavity corresponding region is opened on the front surface side and the through hole corresponding region is opened on the back surface side are formed. In this state, dry etching E2 is performed using the metal layer 101 and the metal layer 102 as a mask, and etching is performed in the thickness direction of the glass wafer. Dry etching is etching using reactive gas or ion milling, and has better etching directivity than wet etching, so that the inner wall angle formed is larger and formed at an angle. Is done. Specifically, the inner wall angle is about 75 degrees.

By such etching, a cavity having an inner bottom surface 11, a lower cavity inner wall 10b, a step portion 1c, and an upper cavity inner wall 10a is formed, and through holes 11a and 11b are formed by dry etching from the outer bottom surface 112 side. The through holes 11a and 11b are in communication with the cavity.

In wet etching, the etching state can be controlled to a certain degree by selecting etching conditions such as an etching solution, a liquid temperature, and a liquid flow, and the inner wall angle can be adjusted to 45 degrees or more and 45 degrees or less. . Also, in dry etching, the etching state can be controlled to a certain degree by selecting etching conditions such as etching gas, temperature, and voltage, and the inner wall angle can be adjusted to 75 degrees or more and 75 degrees or less.

Thereafter, as shown in FIG. 8, the vias 13 and 14 are formed by filling the through holes 11a and 11b with a metal material. In filling the metal material, a seed layer (underlying metal film) is formed in advance by a film deposition technique such as vacuum vapor deposition or sputtering, and the metal material is formed by a technique such as plating using the seed layer as a base point. That's fine. Furthermore, an electrode having a metal film patterned is formed on each of the inner bottom, the inner wall of the lower cavity, and the upper surface of the step. In addition, after formation of the via and the electrode, an individual base is obtained from the glass wafer by cutting along a dotted line B shown in FIG.

  2 and 3, the crystal diaphragm 2 is conductively bonded to the electrode pads 12 and 13 using the conductive bonding material S as shown in FIGS. 2 and 3, and after undergoing frequency adjustment and thermal stabilization processing, A lid is mounted on the opening, and the metal brazing material is melted and hermetically sealed to obtain a piezoelectric vibration device. Note that a wafer-integrated base may be used, and after mounting the quartz crystal vibration plate and hermetically sealing with a lid, the glass wafer may be separated into individual piezoelectric vibration devices.

  Furthermore, in the above-described embodiment, the piezoelectric vibration device having the structure in which the quartz diaphragm is housed as the electronic component element is illustrated, but the quartz diaphragm and the integrated circuit element (IC chip) constituting the oscillation circuit are housed integrally. You may apply to a crystal oscillator.

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit, gist, or main features. For this reason, 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 such as crystal resonators.

DESCRIPTION OF SYMBOLS 1 Base 10 Bank part 11 Bottom part 1a Upper cavity 1b Lower cavity 2 Crystal diaphragm (piezoelectric diaphragm)
3 Lid

Claims (4)

An electronic component package comprising a base having a cavity for housing an electronic component element having electrodes formed thereon and an external connection terminal electrically connected to the electrode, and a lid for hermetically sealing the cavity. Because
The electronic component package, wherein the cavity has an upper cavity and a lower cavity located below the upper cavity, and an inner wall angle of the lower cavity is smaller than an inner wall angle of the upper cavity. 2. The electronic component package according to claim 1, wherein an inner wall angle of the lower cavity is in a range of 35 degrees to 50 degrees. 3. The electronic component package according to claim 1, wherein an inner wall angle of the upper cavity is in a range of 60 to 85 degrees. 4. The electronic component package according to claim 1, wherein the electronic component element is a piezoelectric vibration element in which an excitation electrode is formed, and the piezoelectric vibration element is disposed in the upper cavity. Piezoelectric vibration device.

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