JP4275396B2 - Crystal oscillator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface mount crystal resonator (hereinafter referred to as a surface mount resonator) as an industrial technical field, and more particularly to an electrode structure of a crystal resonator connected using a eutectic alloy.
[0002]
[Prior art]
(Background of the Invention) Surface mounted resonators are small and light, and are used as a reference source for frequency and time of mobile devices such as mobile phones. In recent years, higher reliability and higher frequency have been demanded, and due to this, a review of the holding structure and the like has been demanded.
[0003]
4 and 5 are diagrams for explaining a conventional example, FIG. 4 is an exploded view of a surface-mounted vibrator, FIG. 5 (a) is a sectional view of a crystal piece, and FIG. FIG. (B) is a plan view.
[0004]
The surface-mounted vibrator is formed by housing a crystal piece 2 in a container body 1 and covering a cover 3, and sealing the crystal piece 2. The container main body 1 is made of, for example, a concave laminated ceramic, and has a pair of metallized layers (crystal terminals) 4 as connection terminals for the crystal piece 2 on the inner bottom surface. On the outer surface (bottom surface and side surface), there are mounting electrodes (not shown) for surface mounting electrically connected to the crystal terminals 4.
[0005]
The quartz crystal piece 2 has excitation electrodes 5 on both main surfaces, and leads electrodes 6 for external connection are formed on both sides of one end through extraction electrodes. The lead-out electrodes 6 are formed by folding back to the opposite surface through the side surfaces of the corners. Each of these electrodes is formed by vapor deposition or the like from the main surface of the crystal piece 2 with the first layer being the base electrode 8 and the second layer being the conduction electrode 9. Here, the first layer (base electrode 8) is Cr, and the second layer (conduction electrode 9) is Au. Since the crystal piece 2 and Au as the conductive electrode 9 have low adhesion strength, Cr is interposed as a base electrode 8 that is familiar to them.
[0006]
Then, the lead-out electrodes 6 on both sides of the one end are fixed by the conductive adhesive 7 so as to face the crystal terminals 4 on the inner bottom surface corresponding to the lead electrodes 6. For example, a cover 3 made of metal is joined to a metal ring or metallization layer (not shown) provided on the opening end surface of the container body 1 by seam or beam welding.
[0007]
[Problems to be solved by the invention]
(Problems of the prior art) However, the surface mount resonator having the above-described configuration has the following problems due to the holding structure in which the crystal piece 2 is fixed by the conductive adhesive 7. That is, the conductive adhesive 7 is based on, for example, a silicon-based resin made of a polymer as an organic substance.
[0008]
For this reason, for example, when the conductive adhesive 7 is cured, an emitted gas is generated from the organic substance, which adheres to the crystal piece 2 and deteriorates the aging characteristics. In particular, as the frequency increases (for example, 100 MHz or more) and the crystal piece 2 becomes thinner, the influence becomes larger and the problem becomes more prominent. The same applies when the specifications are strict and high reliability is required.
[0009]
(Object of the Invention) An object of the present invention is to provide a crystal resonator which improves secular change characteristics and vibration characteristics, and promotes high frequency and high reliability.
[0010]
[Patent Document 1]
Japanese Patent Application No. 2002-138441 [0011]
[Means for Solving the Problems]
The present invention, as shown in the claims (claim 1), the electrode lead-out portion of a connection terminal is provided extending the extraction electrode from the excitation electrodes formed on both main surfaces of the crystal piece, the crystal A crystal resonator in which an electrode lead-out portion is connected to a crystal terminal of a container main body in which the crystal piece is accommodated by a eutectic alloy, and an electrode structure of the electrode lead-out portion is from a main surface of the crystal piece. The first layer is a base electrode, the second layer is a conduction electrode, the third layer is a diffusion prevention electrode, the fourth layer is a shielding electrode, the fifth layer is a junction electrode, and the first layer base electrode and the second layer conduction electrode are Extending from the excitation electrode as the same structure as the excitation electrode, the third-layer diffusion prevention electrode is made of a metal that prevents the fourth-layer shielding electrode from diffusing into the conduction electrode, and the fourth-layer Eating of the shielding electrode and the conducting electrode when melting of the five-layer junction electrodes A metal to suppress Les, the more under the eye ground electrode is a Cr or NiCr, said second layer of conductive electrodes and Au, the third layer of anti-diffusion electrode and Au, said fourth layer of shielding electrode Cr or NiCr is used, and the fifth-layer bonding electrode is AuGe.
[0012]
Delete [0013]
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Delete [0015]
Delete [0016]
【Example】
FIG. 1 is a partial cross-sectional view of a surface-mounted vibrator for explaining an embodiment of the present invention. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.
[0017]
As described above, the surface-mounted vibrator is formed by housing the crystal piece 2 in the container body 1 and covering the cover 3 and sealingly sealing it. As described above, the quartz crystal piece 2 has the excitation electrodes 5 on both main surfaces, and the lead-out electrodes 6 formed by being connected and folded on both ends (see FIGS. 4 and 5).
[0018]
The lead electrode 6 has a five-layer structure, and the first base electrode 8 is Cr and the second conductive electrode 9 is Au as described above. Then, here, the diffusion preventing electrode 10 is formed as the third layer, the shielding electrode 11 is formed as the fourth layer, and the bonding electrode 12 is formed thereon as the fifth layer on the second conductive electrode 9 by vapor deposition or the like. .
[0019]
In this example, the third-layer diffusion prevention electrode 10 is Au, the fourth-layer shielding electrode 11 is Cr, and the fifth-layer bonding electrode 12 is a eutectic alloy made of AuGe. In the figure, the thickness of each layer is the same, but the Cr of the base electrode 8 is about 100 angstroms, the Au of the conductive electrode 9 is 300 angstroms or more, the Au of the diffusion preventing electrode 10 is 3000 angstroms, and the Cr of the shielding electrode 11 The junction electrode 12 is set to 2000 angstroms or more, and 4500 angstroms or more.
[0020]
In such a case, the bonding metal 13 is provided on the crystal terminal 4 of the container body 1. The bonding metal 13 is a eutectic alloy AuGe having a thickness of about 30 μm. Then, using a jig (not shown), both sides of one end of the crystal piece 2 are heated and pressed. In short, the bonding electrode 12 and the bonding metal 13, both of which are eutectic alloy AuGe, are melted by thermocompression bonding, and both ends of one end of the crystal piece 2 are electrically and mechanically connected to the crystal terminal 4.
[0021]
With such a configuration, the crystal piece 2 using the eutectic alloy AuGe is joined without using the conventional conductive adhesive, and there is almost no organic matter in the container body 1. Therefore, since the emitted gas does not adhere to the crystal piece 2, the secular change characteristic is maintained well, and the high reliability and high frequency of the surface mount vibrator are promoted.
[0022]
Further, a diffusion prevention electrode 10 (Au) and a shielding electrode 11 (Cr) are interposed between the second-layer conductive electrode 9 (Au) and the fifth-layer bonding electrode 12 (eutectic alloy AuGe). Therefore, at the time of thermocompression bonding, the molten bonding metal 13 and the bonding electrode (AuGe) 12 are blocked by the shielding electrode 11 (Cr) and prevented from being eaten without proceeding to the diffusion preventing electrode 10 and the conduction electrode 9 (Au). (Patent Document 1).
[0023]
In the case where there is no shielding electrode 11, the diffusion preventing electrode 10 and the conductive electrode 9 (Au) are attracted to the bonding metal 13 and the bonding electrode (AuGe) to cause so-called biting and peeling. This causes poor conduction. Therefore, in this embodiment, the shield electrode 11 (Cr) prevents the diffusion preventing electrode 10 and the conduction electrode 9 from being eroded, and the conduction can be reliably maintained.
[0024]
Further, here, the diffusion preventing electrode 10 (Au) is interposed between the conducting electrode 9 and the shielding electrode 11 (Cr). Therefore, Cr of the shielding electrode 11 is absorbed by the diffusion preventing electrode (Au), preventing diffusion to the conduction electrode 9 (Au) and keeping the conduction resistance small. In short, the thickness of the Au layer is increased to prevent Cr diffusion. Thereby, an increase in crystal impedance due to an increase in conduction resistance is suppressed.
[0025]
Although the thickness of the conductive electrode 9 (Au) itself may be increased, it is necessary to reduce the mass of the excitation electrode 6 so that the vibration characteristics are not hindered at high frequencies (for example, 100 MHz or higher). Therefore, the diffusion preventing electrode 10 is required separately from the conduction electrode 9.
[0026]
[Other matters]
In the above embodiment, the crystal piece 2 is described as a flat plate, but it may be as shown in FIG. That is, the conductive electrode 6 may be formed on the thick outer peripheral portion by reducing the thickness of the vibration region, and the outer peripheral portion may be held by the eutectic alloy. Here, the lead-out electrodes 6 on both sides of the one end are formed on the opposite surfaces by the electrode through holes 14, respectively.
[0027]
Further, as shown in FIG. 3, the lead-out electrode 6 is not formed on the opposite surface but is formed only on one main surface side and joined by a eutectic alloy as described above, and the other main surface is simply a base electrode. 8 (Cr) and conductive electrode 9 (Au) may be led out by wire bonding 15.
[0028]
In addition, although the first base electrode 8 is Cr, for example, Ti, NiW, NiTi, NiCr or the like may be used as long as the crystal piece 2 and the second-layer conductive electrode 9 are familiar. Further, although the conductive electrode 9 is Au, basically, for example, any material having good conductivity of Ag or Al may be used. Further, although the fifth-layer bonding electrode 12 is AuGe, it may be Au, Ag, or the like, as long as it is a metal familiar to the bonding metal 13 (AuGe).
[0029]
The bonding metal is AuGe. However, for example, AuSi (melting temperature 363 ° C.) can also be applied. Basically, it is an eutectic alloy made of an inorganic material and having a melting temperature of 573 ° C. or less. . Further, although the fourth-layer shielding metal 11 is Cr, NiCr may be used, for example, and these are selected from the balance between the second-layer conductive electrode 9 and the fifth-layer bonding electrode 12.
[0030]
Further, although described as a crystal resonator, the present invention can be applied to a case where an oscillator or the like is accommodated together with other circuit elements, and the present invention does not exclude this.
And although the container main body 1 provided the step part in the recessed part, even if there is no step part, you may carry out the thermocompression bonding directly to an inner bottom face. Moreover, the container main body 1 may join the concave cover 3 as flat form, and these can be changed arbitrarily.
[0031]
【The invention's effect】
The present invention is as described above, and basically obtained a surface-mount resonator in which a crystal piece is bonded by thermocompression bonding using a eutectic alloy. It is possible to provide a surface mount resonator with high quality and high reliability. Then, good vibration characteristics by maintaining a small conduction resistance of conductive electrodes by the shield electrode and the diffusion prevention electrode, facilitating miniaturization and high frequency.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a surface-mounted vibrator for explaining an embodiment of the present invention.
FIGS. 2A and 2B are diagrams illustrating another embodiment of the present invention, in which FIG. 2A is a partial cross-sectional view of a surface-mounted vibrator, and FIG. 2B is a plan view of a crystal piece.
FIG. 3 is a diagram illustrating still another embodiment of the present invention, and is a partial cross-sectional view of a surface-mounted vibrator.
FIG. 4 is an assembly diagram of a surface-mounted vibrator for explaining a conventional example.
5A and 5B are diagrams for explaining a conventional example, in which FIG. 5A is a cross-sectional view of a crystal piece, and FIG. 5B is a plan view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Container body, 2 Crystal piece, 3 Cover, 4 Crystal terminal, 5 Excitation electrode, 6 Derivation electrode, 7 Conductive adhesive, 8 Ground electrode, 9 Conduction electrode, 10 Diffusion prevention electrode, 11 Shielding electrode, 12 Joining electrode, 13 Bonding metal, 14 Electrode through hole, 15 Wire bonding.

Claims (1)

A container in which the lead-out electrode is extended from the excitation electrodes formed on both main surfaces of the crystal piece to provide an electrode lead-out portion as a connection terminal, and the crystal lead-out portion is made of a eutectic alloy. A crystal unit connected to the crystal terminal of the main body ,
The electrode structure of the electrode lead-out part is that the first layer from the main surface of the crystal piece is a base electrode, the second layer is a conduction electrode, the third layer is a diffusion prevention electrode, the fourth layer is a shielding electrode, and the fifth layer is a bonding electrode. ,
The first-layer base electrode and the second-layer conductive electrode extend from the excitation electrode as the same structure as the excitation electrode,
The third-layer diffusion prevention electrode is made of a metal that prevents the fourth-layer shielding electrode from diffusing into the conductive electrode,
The fourth-layer shielding electrode is made of a metal that suppresses biting of the conductive electrode when the fifth-layer joining electrode is melted ,
The first layer base electrode is Cr or NiCr, the second layer conductive electrode is Au, the third layer diffusion prevention electrode is Au, the fourth layer shielding electrode is Cr or NiCr, and the fifth layer A crystal resonator characterized in that the eye bonding electrode is AuGe.

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