JP5716594B2 - Piezoelectric vibration device - Google Patents

Description

  The present invention relates to a piezoelectric vibration device such as a surface-mounted crystal oscillator used in various electronic devices. In particular, the present invention relates to miniaturization of a piezoelectric vibration device.

  In recent years, various information devices and various mobile communication devices are rapidly becoming thinner and smaller. For this reason, further miniaturization is demanded for piezoelectric vibration devices such as crystal oscillators used for these.

  As an example of the crystal oscillator corresponding to the miniaturization, there is a crystal oscillator having a configuration shown in Patent Document 1, for example. FIG. 6 shows a conventional example having another configuration. In FIG. 6, the crystal oscillator 1 is provided with a recess 21 for accommodating the crystal resonator element 4 on the upper surface of a ceramic container (package 2), and a recess 23 for accommodating the oscillation circuit IC 5 on the lower surface of the package 2. The peripheral edge of the recess 23 is a bank portion 24 formed thicker (higher) than the thickness (height) of the IC 5, and an external connection terminal 51 is formed on the lower surface of the bank portion 24. The IC 5 is joined to the package 2 via the metal bumps B so that the active surface faces the inner bottom surface 230 of the recess 23, and terminals (not shown) for external connection terminals on the active surface of the IC 5 are internal connection conductors. The external connection terminal 51 is electrically connected via M. Similarly, a connection terminal (not shown) to the piezoelectric vibration element on the active surface of the IC 5 is also electrically connected to the crystal vibration element 4 via the internal connection conductor M. Here, in order to form the internal connection conductor M inside the bank portion 24, the width of the bank portion 24 needs to be secured to some extent. However, when the piezoelectric vibration device is miniaturized (for example, the external dimensions of a crystal oscillator having a rectangular shape in plan view are 2.0 mm × 1.6 mm or less), it becomes difficult to ensure the width of the bank portion. come.

JP 2004-146966 A

  The present invention has been made in view of this point, and an object of the present invention is to provide an ultra-small piezoelectric vibration device that realizes space saving and has good characteristics.

In order to achieve the above object, according to the present invention, a piezoelectric vibration element is disposed on one main surface side of a package of a piezoelectric vibration device, the piezoelectric vibration element is sealed by a lid, and the other main surface side of the package is sealed. A concave portion for accommodating an electronic component element is formed, and a piezoelectric vibration device in which a whole region or a partial region of one main surface of the electronic component element is bonded to an inner bottom surface of the concave portion via a resin material, The other main surface of the electronic component element is an active surface, and the conductive member formed on the connection terminal of the other main surface is an external connection terminal of the piezoelectric vibration device, and the recess is deeper than the thickness of the electronic component element. While being formed, a part of the conductive member protrudes below the lower surface of the piezoelectric vibration device.

  According to the above configuration, the piezoelectric vibration device can be reduced in size. This will be described in comparison with a conventional structure by taking a crystal oscillator as an example. In a crystal oscillator having a conventional structure, an electrode pad formed on one main surface of an electronic component element (IC chip or the like) is surrounded by a gold wire or the like in a recess formed in the crystal oscillator package. The structure is led to the external connection terminal on the lower surface of the package via the internal connection conductor formed in the bank portion (hereinafter referred to as the bank portion).

  On the other hand, in the structure of the present invention, the conductive member formed on the connection terminal on the active surface (one main surface on which the circuit pattern or wiring is formed) of the electronic component element is used as the external connection terminal of the piezoelectric vibration device. Use as Therefore, it is not necessary to form external connection terminals on the package side. That is, since it is not necessary to form an external connection terminal on the bank portion, it is not necessary to form an internal connection conductor on the bank portion. Thereby, since the width of the bank portion can be made narrower than before, the piezoelectric vibrating device can be miniaturized. The electronic component element may be, for example, an IC chip that constitutes a piezoelectric oscillation circuit together with the piezoelectric oscillation element, or may be added to the piezoelectric oscillation circuit to constitute an additional circuit such as a temperature compensation circuit or a voltage control circuit. .

  In the present invention, a spherical body made of a conductive material (for example, a solder ball), a prismatic conductor (conductor block), a stud bump, a plated bump, a cured product of a conductive adhesive, or the like is used as the conductive member. In addition to these, the core member made of ceramic, resin, or the like may be coated with a conductive material. In this case, metal plating, a paste-like conductor, or the like can be employed as the conductive material.

  According to the above configuration, the electronic component element has the whole or a part of one main surface of the electronic component element bonded to the inner bottom surface of the concave portion via the resin material. Thereby, the resin material functions as a buffer material for external stress. Specifically, since the electronic component element is bonded to the package via the resin material, the stress generated when the external connection terminal of the piezoelectric vibration device is bonded to the external board (user use board) is propagated to the package. Can be relaxed. Since stress propagation to the piezoelectric vibration element through the package can be relaxed, a piezoelectric vibration device having stable characteristics can be obtained.

Furthermore, the recess is formed deeper than the thickness of the electronic component element, and a part of the conductive member protrudes below the lower surface of the piezoelectric vibration device. With the above structure, in a state where the electronic component element is bonded to the inner bottom surface of the recess, the electronic component element does not protrude outward from the recess (outside from the package lower surface) and only a part of the conductive member. Can protrude from the recess to the outside. As a result, the conductive member can sufficiently secure the connection strength between the piezoelectric vibration device and the external substrate (user use substrate), and only a part of the conductive member protrudes from the package. The height can be reduced as compared with a piezoelectric vibration device having a structure in which conductive members are joined.

Furthermore, in order to achieve the above object, the recess may be filled with an insulating resin. According to the said structure, the electronic component element accommodated in the recessed part can be hold | maintained stably. Specifically, since the insulating resin can be held by the side wall of the bank portion described above, the electronic component element in contact with the insulating resin can be stably held. The insulating resin does not necessarily need to be filled in the entire space of the recess, and may be filled to a depth that contacts a part of the side surface of the IC, for example. If the recess is filled with an insulating resin so that the entire electronic component element and a part of the conductive member are covered, the electronic component element is more securely held and a part of the conductive member is provided. Is preferable because it is held by an insulating resin. In addition, when an IC is used as an electronic component element, there is a method in which the electrode pad of the IC and the electrode pad formed on the package are connected by a gold wire or the like. It is desirable to fill the insulating resin to the depth to cover. Specifically, the filling is preferably performed so as to be slightly recessed from the lower surface of the package toward the inner bottom surface of the recess.

  As described above, according to the present invention, it is possible to provide an ultra-small piezoelectric vibration device that realizes space saving and has good characteristics.

1 is a cross-sectional view of a crystal oscillator according to a first embodiment of the present invention. It is the top view seen from the bottom face of FIG. It is sectional drawing of the crystal oscillator which concerns on the 2nd Embodiment of this invention. It is the top view seen from the bottom face of FIG. It is sectional drawing of the crystal oscillator which concerns on the modification of the 2nd Embodiment of this invention. It is sectional drawing of the conventional crystal oscillator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the first and second embodiments of the present invention, an example in which the present invention is applied to a surface-mounted crystal oscillator will be described. In the first and second embodiments of the present invention, an IC chip is used as the electronic component element.

-First embodiment-
FIG. 1 is a cross-sectional view of the crystal oscillator according to the first embodiment of the present invention, and FIG. 2 is a plan view as seen from the bottom side of the crystal oscillator in FIG. In FIG. 2, the position of the IC chip covered with the insulating resin is indicated by a broken line for explanation.

  In the embodiment of the present invention, the crystal oscillator 1 includes a crystal resonator element 4 bonded to the upper surface (one main surface) 200 of the package 2 and a main surface (another main surface, which will be described later) facing the external substrate (user use substrate). The same as the package lower surface 220), the package 2 having the recess 23 for accommodating the electronic component element, the IC chip 5 accommodated in the recess 23 of the package 2, and the conductive member formed on the active surface 50 of the IC chip 5. 6 and the lid 3 that covers the crystal resonator element 4 and hermetically seals are the main constituent members.

  In FIG. 2, a package 2 is an insulating container made of ceramics such as alumina and having a rectangular shape in plan view. In the present embodiment, the package 2 is formed by firing alumina, and has a structure having a recess 23 on the side of the other main surface of the package 2 (the lower surface 220 of the package 2). A metal layer (not shown) made of tungsten, nickel, or the like is formed on the edge of the upper surface 200 of the package 2 using metallization technology and plating technology. Instead of this metal layer, a metal ring such as a Kovar material may be used. On one end side of the upper surface 200 of the package 2, a pair of piezoelectric vibration element electrode pads 10, 10 for electrically and mechanically bonding the crystal vibration element 4 are formed in parallel. The piezoelectric vibration element electrode pad 10 is electrically connected to an electrode (not shown) formed on the inner bottom surface 230 of the recess 23 via an internal connection conductor M formed using a known ceramic lamination technique. Has been.

  In FIG. 1, a crystal resonator element 4 is formed by forming a pair of excitation electrodes (not shown) for driving the crystal resonator plate on the front and back surfaces of an AT-cut crystal resonator plate. , 10 are led to one end of the crystal diaphragm so as to be connected to the conductive adhesive 9. As shown in FIG. 1, one end side of the crystal vibration element 4 is cantilevered on the piezoelectric vibration element electrode pad 10 via a conductive adhesive 9.

  The crystal resonator element 4 is airtightly bonded by the lid 3 made of metal through the bonding material 8 (see FIG. 2). The lid 3 is a metal lid having an annular thick portion 30 on the periphery, and the entire upper surface of the thick portion 30 is nickel corresponding to the metal layer formed on the periphery of the upper surface 200 of the package 2 described above. The metal layer which consists of etc. is formed. The lid 3 may be a ceramic plate in addition to the metal plate. The package 2 and the lid 3 are hermetically bonded by melting the metal layer around the vapor deposition surface 200 of the package 2 and the metal layer of the thick portion 30 of the lid 3 in an inert gas atmosphere or a reduced pressure atmosphere. Is done. As the joining method, when the lid 3 is a metal plate, well-known seam welding, laser welding, electron beam welding or the like can be used. When the lid 3 is a ceramic plate, a bonding method by glass sealing, resin sealing, or metal brazing material sealing is employed.

  On the other hand, the IC chip 5 is accommodated in the recess 23 of the package 2 as shown in FIG. One main surface 501 of the IC chip 5 is bonded to the inner bottom surface 230 of the recess 23 by the resin material 7. Here, as the resin material 7, for example, an epoxy resin, a silicon resin, a urethane resin, or the like can be used. A circuit element (not shown) is formed on the other main surface 502 of the IC chip 5, and the other main surface 502 is the active surface 50 of the IC chip 5. The other main surface 502 of the IC chip 5 is a terminal for connecting an electrode pad 51 for external connection terminals (hereinafter referred to as an electrode pad for external connection) and a piezoelectric vibration element (not shown; for crystal vibration element connection). Terminal). The crystal resonator element connection terminal is electrically connected to a through electrode 52 penetrating the IC chip 5 in the thickness direction. An end (hereinafter abbreviated as “upper end”) of the recess 23 of the through electrode 52 on the inner bottom surface 230 side is connected to an electrode pad (not shown) formed on the inner bottom surface 230, and passes through the internal connection conductor M. Thus, the piezoelectric vibration element electrode pad 10 is electrically connected.

  In FIG. 2, the IC chip 5 is joined to the inner bottom surface 230 of the recess 23 by the insulating resin material 7 so that the active surface 50 faces the opening 22 of the recess 23. Specifically, a conductive resin material (not shown) is provided only for a minute junction region between the electrode pad (not shown) formed on the inner bottom surface 230 of the recess 23 and the upper end of the through electrode 52 to ensure conduction. The other main surface 502 of the other IC chip 5 is bonded with an insulating resin material 7. That is, a part of the other main surface 502 of the IC chip 5 (refers to a large part of the other main surface 502) is joined to the other main surface 502 by the insulating resin material 7. Thereby, the resin material 7 functions as a buffer material for external stress. Specifically, since the IC chip 5 is bonded to the package 2 via the resin material 7, when the external connection terminal (conductive member 6) of the crystal oscillator 1 is bonded to the external substrate (user use substrate). Propagation of the generated stress to the package 2 can be mitigated. Since the stress propagation to the piezoelectric vibration element through the package can be relaxed, a crystal oscillator having stable characteristics can be obtained.

  A conductive member 6 is conductively bonded to the external connection electrode pad 51, and this conductive member 6 serves as an external connection terminal of the crystal oscillator 1. As a specific configuration of the external connection terminal, a conductive member using BGA (Ball Grid Alley) technology is used. In this embodiment, a solder ball made of a solder material is used, but other conductor balls (a spherical body made of a conductive material) can be used instead of the solder balls (for example, gold ball). This type of conductive member can sufficiently secure the connection strength to the package even when the space for forming the external connection terminals is relatively narrow.

  A part of the conductive member 6 protrudes outward from the recess 23, that is, below the lower surface 220 of the package 2. With the above structure, in a state where the IC chip 5 is bonded to the inner bottom surface 230 of the recess 23, the IC chip 5 does not protrude outward from the recess 23 (outside from the lower surface 220 of the package 2), and is conductive. Only a part of the member 6 can protrude from the recess 23 to the outside. Thus, the conductive member 6 can sufficiently secure the connection strength between the crystal oscillator 1 and the external substrate (user use substrate), and only a part of the conductive member 6 protrudes from the package 2. The height can be reduced compared to a crystal oscillator having a structure in which a conductive member is bonded to the lower surface of the package.

  In addition, the recess 23 is filled with an insulating resin R. In this embodiment, an epoxy resin is used as the insulating resin R. However, a silicon resin or a urethane resin can be used in addition to the epoxy resin. Note that it is preferable to use the same kind of resin for the resin material 7 and the insulating resin R (including the minute bonding region at the upper end of the through electrode 52) because the difference in thermal expansion coefficient between the resins is eliminated.

  The insulating resin R is filled in the recess 23 so as to cover the entire IC chip 5, and a part of the conductive member 6 is also covered with the insulating resin R. The filling depth of the insulating resin R is a depth that does not protrude outward from the lower surface 220 of the package 2. According to the said structure, the IC chip 5 accommodated in the recessed part 23 can be hold | maintained stably. Specifically, since the insulating resin R can be held by the side wall of the bank portion 24, the IC chip 5 in contact with the insulating resin R can be stably held. The insulating resin R does not necessarily need to be filled in the entire space of the recess 23, and may be filled to a depth that is in contact with a part of the side surface of the IC chip 5, for example. In addition, if the insulating resin R is filled so that the whole of the IC chip 5 and a part of the conductive member 6 are covered in the recess 23, the IC chip 5 can be held more reliably and conductive. A part of the member 6 is preferably held by the insulating resin R. Specifically, as shown in FIG. 1, filling is preferably performed such that the package 2 is slightly recessed from the lower surface 220 of the package 2 toward the inner bottom surface 230 of the recess 23.

  According to the above configuration, the IC chip 5 is bonded to the inner bottom surface 230 of the recess 23 with a part of one main surface 501 of the IC chip 5 via the resin material 7, and the other main surface 502 of the IC chip 5 is active. The conductive member 6 is conductively bonded to the external connection electrode pad 51 formed on the other main surface 502 and functions as an external connection terminal of the crystal oscillator 1. With such a configuration, the piezoelectric vibration device can be reduced in size. Taking a crystal oscillator as an example, a crystal oscillator having a conventional structure has an electrode pad formed on one main surface of an electronic component element (IC chip or the like) in a recess formed in a package of the crystal oscillator by a gold wire or the like. The structure is led out to an external connection terminal on the lower surface of the package via an internal connection conductor formed in an annular bank portion surrounding the recess of the package. On the other hand, in the structure of the present invention, the conductive member formed on the connection terminal on the active surface side of the electronic component element is used as the external connection terminal of the piezoelectric vibration device. Therefore, it is not necessary to form external connection terminals on the package side. That is, since it is not necessary to form an external connection terminal on the bank portion, it is not necessary to form an internal connection conductor on the bank portion. Thereby, since the width of the bank portion can be made narrower than before, the piezoelectric vibrating device can be miniaturized.

-Second Embodiment-
FIG. 3 is a cross-sectional view of a crystal oscillator according to a second embodiment of the present invention, and FIG. 4 is a plan view as seen from the bottom side of the crystal oscillator in FIG. 3 to 4, for the sake of explanation, the position of the IC chip covered with the insulating resin and the gold wire (described later) are indicated by broken lines. In the second embodiment of the present invention, the same components as those in the first embodiment are denoted by the same reference numerals and a part of the description is omitted, and the same effects as those of the above-described embodiments are obtained. Hereinafter, a description will be given focusing on differences from the first embodiment.

  The package 2 according to the second embodiment of the present invention has two concave portions (an upper concave portion 21 and a lower concave portion 23) on the upper and lower sides of the insulating base material as in the modification of the first embodiment. A step portion 25 is formed on one end side of the lower recess portion 23. An electrode pad 26 (not shown in FIG. 4) is formed on the surface of the step portion 25, and the electrode pad 26 is electrically connected to the piezoelectric vibration element electrode pad 10 via the internal connection conductor M. .

  In this embodiment, the IC chip 5 is joined to the inner bottom surface 230 of the lower recess 23 by the resin material 7 so that the active surface 50 faces the opening 22 of the lower recess 23 as in the first embodiment. . In the present embodiment, the resin material 7 may be either conductive or insulating resin material. In this embodiment, since the electrical connection between the connection terminal of the IC chip 5 to the crystal vibration element 4 and the electrode pad 10 for the piezoelectric vibration element is performed through the gold wire and the internal connection conductor, the IC chip 5 This is because no through electrode is formed on the main surface 501 of the IC chip 5 and no terminal is led out from the terminal for connection with the crystal resonator element 4. That is, the IC chip 5 is bonded to the inner bottom surface 230 of the lower recess 23 with the resin material 7 interposed in the entire region on the one main surface 501 of the IC chip 5. Thereby, the resin material 7 functions as a buffer material for external stress. Specifically, since the IC chip 5 is bonded to the package 2 through the resin material 7, the package 2 has a stress generated when the external connection terminal (conductive member 6) of the crystal oscillator 1 is bonded to the external substrate. Propagation to can be reduced. Since the stress propagation to the piezoelectric vibration element through the package can be relaxed, a crystal oscillator having stable characteristics can be obtained.

  On the periphery of the active surface 50 of the IC chip 5, connection terminals (not shown) between the external connection electrode pads 51 and the piezoelectric vibration elements are formed. Specifically, in FIG. 4, four external connection electrode pads 51, 51, 51, 51 are formed below the four conductive members 6, 6, 6, and 6. Between the external connection electrode pads 51 and 51 arranged in parallel in the short side direction, connection terminals for two piezoelectric vibration elements are formed (not shown). The connecting terminal for connection with the piezoelectric vibration element is electrically connected to the electrode pad 26 (not shown) by the wire bonding method using a gold wire (the wire is indicated by a dotted line with a symbol W in FIGS. 3 to 5). Display). Aluminum wire can be used in addition to gold wire.

  As shown in FIGS. 3 to 4, the lower recess 23 is filled with an insulating resin R. Also in this embodiment, an epoxy resin is used as the insulating resin R. The insulating resin R is filled so as to cover the entire IC chip 5 and also cover the electrode pads 26 and the entire wires W on the step portion 25 and a part of the conductive member 6. The filling depth of the insulating resin R is a depth that does not protrude outward from the lower surface 220 of the package 2.

  According to the above-described configuration, the IC chip 5 accommodated in the lower recess 23 can be stably held, and at the same time, the entire wire W can be protected. Specifically, since the insulating resin R can be held by the side wall of the bank portion 24, the IC chip 5 in contact with the insulating resin R can be stably held. The insulating resin R does not necessarily need to be filled in the entire space of the lower recess 23, and may be filled to a depth that contacts a part of the side surface of the IC chip 5, for example. If the lower recess 23 is filled with the insulating resin R so that the entire IC chip 5 and a part of the conductive member 6 are covered, the IC chip 5 can be held more reliably and the conductive A part of the conductive member 6 is preferably held by the insulating resin R. In addition, there is a method of connecting the electrode pad of the IC and the electrode pad formed on the package with a gold wire or the like as in the present embodiment. It is desirable to fill with an insulating resin.

  A part of the conductive member 6 protrudes outward from the lower recess 23, that is, below the lower surface 220 of the package 2. With such a structure, in a state where the IC chip 5 is bonded to the inner bottom surface 230 of the recess 23, the IC chip 5 does not protrude outward from the recess 23 (outside from the lower surface 220 of the package 2), and Only a part of the conductive member 6 can protrude from the recess 23 to the outside. As a result, the conductive member 6 can sufficiently secure the connection strength between the crystal oscillator 1 and the external substrate, and only a part of the conductive member 6 protrudes from the package 2. The height can be reduced as compared with a crystal oscillator having a structure in which members are joined.

  Further, according to the present embodiment, the IC chip 5 is bonded to the inner bottom surface 230 of the lower recess 23 with the entire main surface 501 of the IC chip 5 via the resin material 7, and the other main surface 502 of the IC chip 5 is The conductive member 6 is conductively bonded to the external connection electrode pad 51 formed on the other main surface 502 and functions as an external connection terminal of the crystal oscillator 1. With such a configuration, the piezoelectric vibration device can be reduced in size. That is, with the above configuration, the conductive member formed on the connection terminal on the active surface side of the electronic component element is used as the external connection terminal of the piezoelectric vibration device. Therefore, it is not necessary to form external connection terminals on the package side. That is, since it is not necessary to form an external connection terminal on the bank portion, it is not necessary to form an internal connection conductor on the bank portion. Thereby, since the width of the bank portion can be made narrower than before, the piezoelectric vibrating device can be miniaturized.

  As a modification of the second embodiment of the present invention, as shown in FIG. 5, the step portion 25 is not formed on the package 2, and the crystal vibration element connection terminal of the IC chip 5 and the electrode pad 10 for the piezoelectric vibration element are provided. A configuration in which electrical connection is performed through the through electrode 52 may be employed.

  The present invention can be applied to a piezoelectric vibration device of a package having a recess that accommodates an electronic component element. However, the present invention is not limited to the piezoelectric vibration device having the structure of the first or second embodiment. A package of a piezoelectric vibrator (with a piezoelectric vibration element joined in a package and hermetically sealed with a lid) on a main surface on the side where the concave portion is not formed. The present invention can also be applied to a structure in which these are electromechanically joined. In addition, as the material of the package (container body) used in the present invention, ceramics are used in the first and second embodiments. However, the present invention is not limited to this, and glass, crystal, silicon other than ceramics is used. It is also possible to use materials such as

  The present invention is not limited to quartz, but can be applied to a piezoelectric vibration device including a piezoelectric vibration element using lithium niobate or lithium tantalate.

  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.

DESCRIPTION OF SYMBOLS 1 Crystal oscillator 10 Electrode pad for piezoelectric vibration elements 2 Package 21 Upper recessed part 23 Lower recessed part 230 Inner bottom face (lower recessed part)
24 Bank portion 3 Lid 4 Crystal vibrating element 5 IC chip 50 Active surface 51 External connection electrode pad 52 Through electrode 6 Conductive member 7 Resin material R Insulating resin

Claims (2)

A piezoelectric vibration element is arranged on one main surface side of the package of the piezoelectric vibration device, and the piezoelectric vibration element is sealed with a lid,
A concave portion for accommodating the electronic component element is formed on the other main surface side of the package, and the whole or part of one main surface of the electronic component element is bonded to the inner bottom surface of the concave portion via a resin material. A piezoelectric vibration device,
The other main surface of the electronic component element is an active surface, and a conductive member formed on the connection terminal of the other main surface is used as an external connection terminal of the piezoelectric vibration device, and the concave portion is larger than the thickness of the electronic component element. A piezoelectric vibration device characterized in that the piezoelectric vibration device is deeply formed and a part of the conductive member protrudes below a lower surface of the piezoelectric vibration device.   The piezoelectric vibration device according to claim 1, wherein the recess is filled with an insulating resin.

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