JP2003224443A - Crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crystal device having a thin crystal oscillator by employing a thin base substrate, along with preventing with respect to degradation in the CI (crystal impedance) value of the crystal oscillator. <P>SOLUTION: Electrode pads 25 and 25, which are formed on a flat base substrate in a separated fashion, are coated by anisotropic conductivity adhesive member 4 to bond a crystal vibrator 3, with an outward angular section of a drawer electrode. At the bonding section, the anisotropic conductivity adhesive member 4 is formed in between an electrode pad and a sealing ring near the electrode pad. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal unit in which a crystal unit is bonded to a substrate composed of a substantially flat plate-shaped substrate and a metal frame through a conductive adhesive member obtained by curing a conductive paste. It is about devices.

[0002]

2. Description of the Related Art A conventional crystal device, for example, a crystal oscillator 51, is mainly composed of a ceramic package 52, a crystal oscillator 53, and a conductive adhesive which is an anisotropic conductive adhesive member, as shown in FIGS. And the member 54. Incidentally, FIG.
In, the metal lid is omitted.

The ceramic package 52 has a cavity 520 formed by laminating a frame-shaped substrate 522 on a flat substrate 521 made of a ceramic insulating plate such as alumina. A seal ring 523, which is a metallic frame body made of Fe-Ni, Fe-Ni-Co, or the like, is formed on the upper surface of the frame-shaped substrate 522 around the opening. Further, a crystal oscillator 53 is housed inside the cavity 520.

An external terminal electrode 526 is formed on the lower surface of the ceramic package 52, and a step portion 524 is formed inside the ceramic package 52 over the entire width of the crystal unit 53 in the width direction. Electrode pads 525 and 525, which are separated in the width direction and are connected to the external terminal electrodes 526 and the like, are formed on the portion 524.

Further, the crystal oscillator 53 is provided with excitation electrodes 531 and 5 which face each other on both main surfaces of a rectangular crystal substrate 530.
33 and the excitation electrodes 531 and 533 to the quartz substrate 530.
Of the extraction electrodes 532, 5 extending to one short side of both main surfaces of the
34 is formed. The excitation electrodes 532 and 534 and the extraction electrodes 531 and 533 are formed by means such as vapor deposition. The crystal unit 53 as described above is attached to the step portion 5
Electrode pads 525 and 525 formed separately on 24
Of the extraction electrodes 532 and 534, the electrodes 532b and 534b on the lower surface were mounted on the upper surface.

Further, the conductive adhesive member 54 is made of the conductive particles 5.
An anisotropic conductive adhesive member composed of 42 and a resin 541 as an adhesive, which was formed by curing an anisotropic conductive resin paste by heating or the like. (JP-A-10-34
1128).

[0007]

As shown in FIG. 4, conductive particles 54 included in the anisotropic conductive adhesive member 54 are formed on the lower surfaces of the extraction electrodes 532 and 534 of the crystal unit 53.
2 is pressed, and the step portion 52 of the ceramic package 52 is pressed.
4 was electrically connected so as to be in contact with the electrode pads 525 and 525 formed in No. 4, and the crystal unit 53 was mechanically fixed.

However, a crystal device such as a crystal oscillator typified by the crystal oscillator 53 is required to be small and thin, and if such a crystal device is attempted to be miniaturized, a crystal vibration accommodated inside is required. The child 53 itself also needs to be downsized.

Generally, in a crystal resonator, as shown in FIG. 6, in the case of a rectangular excitation electrode, vibration energy is distributed in the inside and outside of the excitation electrode in a rectangular shape with arcuate concentric corners. The energy goes up toward the center of. Furthermore, in the crystal unit 53, most of the vibration energy is confined inside the excitation electrode to obtain the electrical characteristics.

However, in detail, most of the vibration energy is confined inside the excitation electrode, but the rest is slightly distributed outside the excitation electrode, for example, at the end of the quartz substrate. In particular, when oscillating at a low frequency such as 13 MHz to 20 MHz, the closer the portion holding the crystal substrate using the conductive adhesive member is to the excitation electrode, the more the vibration is impeded. It will worsen the electrical characteristics. As a result, the crystal impedance value (hereinafter referred to as the CI value) was deteriorated as the crystal holding portion was made closer to the excitation electrode.

That is, as shown in FIG. 6, the holding portion of the crystal resonator 53 by the anisotropic conductive adhesive member 54 is the entire widthwise lower surface of the extraction electrode, and the distance from the excitation electrode center is outside the extraction electrode. Whereas Le is at the corner nearer,
When the distance between the excitation electrodes 532b and 534b is the shortest, Lc (Lc <Le) is established and the anisotropic conductive adhesive member 5 is formed.
4, the crystal resonator 53 is held, and at the same time, the electrical characteristics of the crystal resonator 53 are deteriorated.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to prevent deterioration of electric characteristics even if an anisotropic conductive adhesive member is used and to improve productivity, At the same time, it provides a thinned crystal device.

[0013]

In the present invention, excitation electrodes are formed on both main surfaces of a rectangular crystal substrate, and a pair of extraction electrodes connected to the excitation electrodes are formed on the mounting main surface of the crystal substrate. Surrounded by the metal frame body, a flat-plate-shaped insulating substrate, a metal frame body formed on the surface of the insulating substrate to form a cavity for accommodating the crystal resonator, A base comprising a pair of electrode pads formed on the surface of the insulating substrate; and a pair of anisotropic conductive adhesive members connecting the extraction electrodes of the crystal unit and the electrode pads of the base. It is a characteristic crystal device.

Further, the end face of the crystal substrate is fixed to the metal frame body through the anisotropic conductive adhesive member. Further, external terminal electrodes connected to the pair of electrode pads are led out to the bottom surface of the flat insulating substrate through via holes penetrating in the thickness direction of the insulating substrate.

According to the present invention, a metal frame is applied on a flat substrate to form a cavity for accommodating a crystal oscillator, and the cavity is formed on the upper surface of the flat substrate separately in the width direction. A crystal oscillator is connected to the electrode pad, and an anisotropic conductive adhesive member separately applied to each electrode pad is connected to an outer corner of the extraction electrode on the lower surface side. Further, the anisotropic conductive adhesive member is formed so as to cover the electrode pad and the inner surface of the metal frame.

Thus, the holding position of the crystal unit of the conductive adhesive member can be set to the position farthest from the excitation electrode on the extraction electrode, so that the inhibition of vibration can be suppressed and the deterioration of the CI value can be suppressed. be able to.

Further, the application size of the conductive adhesive member may be reduced in order to move the application position of the conductive adhesive member away from the excitation electrode of the crystal unit. In such a case, the conductive adhesive member is provided only on the electrode pad. Instead, since it is formed so as to cover the metal frame, it is possible to increase the substantial holding strength of the crystal unit, and at the same time, since the anisotropic conductive adhesive member is used, the metal frame It is possible to prevent the occurrence of an electrical short circuit even when it comes into contact with.

Further, the above-mentioned base is formed by depositing a metal frame on the flat substrate, and at the same time, the electrode pads on the flat substrate correspond to the external electrode terminals formed on the lower surface of the base. The electrode pad and the external terminal electrode, which are formed at a position, are connected by a via-hole conductor that penetrates the flat substrate in the thickness direction. In addition, the crystal oscillator is housed inside the cavity of the base body in this manner, and then the opening of the cavity is hermetically sealed by using a metal lid body to manufacture a crystal oscillator.

As a result, even if it is manufactured as a crystal oscillator, the crystal oscillator can be made thin in addition to preventing the CI value of the crystal resonator from being deteriorated as described above. As a result, it is possible to reliably and easily achieve a crystal device that has a good CI value and at the same time can achieve thinning.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The crystal device of the present invention will be described below in detail with reference to the drawings.

The crystal oscillator is an oscillator using a crystal plate, and the crystal device is an oscillator having only a single crystal vibrating element, and an IC chip, a capacitor, a resistor, etc. together with the crystal oscillator. This is an oscillator equipped with electronic component elements. Further, the base body is an insulating substrate having a flat plate shape as a whole, a container having a housing shape, or the like.

FIG. 1 is a top view in which the lid of the crystal oscillator of the present invention is omitted, and FIG. 2 is a sectional view taken along the line AA 'in FIG.

The base body 2 is composed of a rectangular flat plate-shaped substrate 21 made of ceramic and a seal ring 22 which is a metal frame body provided around the flat plate-shaped substrate 21. As a result, the seal ring 22 has an opening on the front surface side as shown in FIG. 2 as a whole, and
A substantially rectangular cavity 20 for accommodating the crystal unit 3 is formed.

Further, on the bottom surface of the cavity 20, that is, on one short side (the left side in FIG. 1) of the upper surface of the plate-shaped substrate 21, a pair of electrode pads 2 for electrically connecting with the crystal unit 3 is formed.
5, 25 are formed. This electrode pad 25, 25
Are formed separately in the width direction of the short sides (vertical direction in FIG. 1). Its shape is roughly rectangular.

The seal ring 22 is made of Fe-Ni,
A flat substrate 21 made of a metal such as Fe-Ni-Co
Is formed by brazing or the like on the sealing conductor film 211 formed on the periphery of the base metal, and the surface is plated by a base plating layer made of Ni or Cr in order and further A is formed on the top surface thereof.
A u-plated layer is applied. Moreover, the seal ring 22 is placed on the flat substrate 21 in this way,
It defines the thickness of the cavity 20.

For example, the thickness of the seal ring 22 is 0.1
5 to 0.30 mm, and these are joined by brazing or the like as described above.

On the bottom surface of the base 2, external terminal electrodes 26 are formed for electrically connecting to the electrode pads 25, 25 and for joining to an external printed wiring board. The electrode pads 25, 25 and the external terminal electrodes 26 are formed at positions corresponding to the flat substrate 21, and are connected by via hole conductors 21a that penetrate the flat substrate 21 in the thickness direction.

Further, the bumps 24 may be formed on the surfaces of the electrode pads 25, 25, particularly on the central portion of the cavity 20 in the long side direction. The bumps 24 are formed by baking a conductive metal paste, printing a conductive resin paste and an insulating resin paste, and curing the conductive resin paste.
The positions are separately formed on the pair of electrode pads 25, 25.

The above-mentioned electrode pads 25, 25 and bumps 2
4. The sealing conductor film 211 is made of metal such as molybdenum and tungsten. These conductors are formed by baking a conductive resin paste on the surface of the flat board 21 and then plating the surface with Ni and Au.

For example, when the bump 24 is formed by baking a conductive metal paste, the electrode pads 25, 25
Is formed by printing and forming a conductor serving as a base conductor of the above-mentioned metal paste on the surface thereof after drying, according to the shape of the bumps 24 by using the above-mentioned metal paste, and then baking the both. To be done.

The thickness of these conductors is about 10 to 30 μm.
Therefore, the height from the surface of the flat substrate 21 to the apex of the bump 24 is 20 to 60 μm.

The crystal unit 3 which is a crystal unit is, for example, a rectangular crystal substrate 30 which is cut (AT cut) according to a predetermined crystal azimuth angle, and an excitation which is adhered and formed on both main surfaces of the crystal substrate 30. Electrodes 31 and 33 and a pair of excitation electrodes 3
1 and 33, and lead electrodes 32 and 34 extending in the short side direction (left side in the figure) of the quartz substrate 30, respectively. For example, in the extraction electrode 32 extending from the upper surface side excitation electrode 31, it extends to the vicinity of the short side of the upper surface and is extended to the upper surface side via one long side end surface (the lower end surface in the drawing) near the short side. It has been extended. On the contrary, the extraction electrode 34 extending from the excitation electrode 33 on the lower surface side extends near the short side of the lower surface, and the other long side end surface (upper end surface in the drawing) near the short side. It extends to the upper surface side.
That is, the extraction electrodes 32 and 34 are not formed on the end surface of the quartz substrate 30 on the one short side, but are formed on the end surface of the long side in contact with the one short side. The lead-out electrodes 32 and 34 are formed at positions facing each other on both main surfaces of the crystal substrate 30, and their shapes are such that they can be electrically connected to the electrode pads 25, 25 when arranged at predetermined positions. .

The excitation electrodes 31 and 33 and the extraction electrodes 32 and 34 are formed on the upper surface and the lower surface of the quartz substrate 30,
It is formed by arranging a mask having a predetermined shape and vapor-depositing Au, Ag, Cr or the like using a means such as vapor deposition or sputtering.

The anisotropic conductive adhesive member 4 comprises a resin 41 as an adhesive member and conductive particles 42.
Is formed by plating Au 42b or the like on the outer peripheral surface of a spherical resin 42a which is an elastic body.

Since such an anisotropic conductive adhesive member 4 is used, as shown in FIG. 2, conductive particles are provided between the lower surfaces of the extraction electrodes 32, 34 of the crystal unit 3 and the electrode pads 25, 25 of the substrate 2. 42 are vertically spaced from each other while being pressed from above. Further, the adhesive member 41 flows into the gap. In this way, by the conductive particles 42,
Lead electrodes 32, 34 and electrode pads 2 on both sides of one end
5 and 25 are electrically connected. Also, the crystal unit 3
Lower surface of the extraction electrodes 32, 34 and the electrode pads 25, 25
Parts other than the conductive particles 42 are mechanically connected by the adhesive member 40.

Further, the anisotropic conductive adhesive member 4 is used to electrically and mechanically bond the extraction electrodes 32 and 34 of the crystal unit 3 and the electrode pads 25 and 25, thereby providing crystal vibration. The anisotropic conductive adhesive member 4 is formed between the extraction electrodes 32 and 34 of the child 3 and the inner surface of the seal ring 22 located in the vicinity of each of the extraction electrodes 32. Electrodes 32, 3
4 and the inner surface of the seal ring 22 in the vicinity thereof are not electrically connected to each other, so that they are only mechanically fixed and no electrical short circuit occurs. Therefore, only the holding by the extraction electrodes 32 and 34 can be strengthened without causing the problem of electrical short circuit in the crystal unit 3, and the productivity can be improved.

Furthermore, as shown in FIG. 1, the above-mentioned anisotropic conductive adhesive member 4 is a pair of extraction electrodes 3 of the crystal unit 3.
Separated around the outer corners of the respective 2, 34, they are connected to the electrode pads 25, 25. In this way, the anisotropic conductive adhesive member 4 is also formed separately in two corresponding to each electrode pad 25, so that the crystal oscillator 3 is formed into the excitation electrode 3.
It becomes possible to hold only in the position farthest from 1, 34. As a result, especially 13MHz to 20MHz
When the crystal oscillator 3 for low frequency oscillation as described above is used, the inhibition of vibration can be minimized and a good CI value can be obtained.

As described above, the pair of excitation electrodes 31, 33 of the crystal unit 3 are connected to the base 2 via the electrode pads 25, 25.
Will be connected to the external terminal electrode 26 on the outer surface.

The metallic lid 6 is made of a substantially flat metal,
For example, Fe-Ni alloy (42 alloy) or Fe-Ni-
It is made of Co alloy (Kovar) or the like, and the surface thereof is plated with Ni. Such a metallic lid 6 hermetically seals the accommodation area (cavity) 20 of the crystal unit 3 with nitrogen gas or vacuum. Specifically, the metal lid 6 is placed on the seal ring 22 of the base body 2 in a predetermined atmosphere, and the metal on the surface of the seal ring 22 and a part of the metal of the metal lid 6 are welded. Seam welding is performed by applying a predetermined current as described above. In order to ensure this welding, an Ag brazing layer or the like may be formed in advance on the joint surface side of the metallic lid body 6, and the brazing material melted by welding is A Ni plating layer may be formed on the front surface side of the metallic lid body 6 so that the brazing material that goes around to the front surface side and contributes to the bonding is not reduced.

Further, a quartz oscillator 51 hermetically sealed by using a conventional metal lid 56 of the base 2 having a thickness of 0.1 mm.
Was about 0.8 mm even in the thinnest case, but according to the present invention, the seal ring 22 is adhered onto the flat substrate 51 to form the base body 2, and the thickness of the base substrate 2 is similarly 0.1 m.
Crystal oscillator 1 seam-welded using a metal lid 6 of m
In, the total thickness is about 0.45mm and 0.35m
It is possible to reduce the thickness by about m. Therefore, as described above, by using the base 2 that covers the flat substrate 21 with the seal ring 22 and forms the cavity 20, an ultrathin crystal oscillator can be achieved. .

In practice, after the crystal unit 3 is electrically connected and mechanically bonded to the electrode pads 25, 25, the oscillation frequency of the crystal unit 3 is measured using the external terminal electrodes 26 and the like. If necessary, the frequency is adjusted by depositing Ag or the like on the surface of the upper-side excitation electrode 31 of the crystal unit 3 or by irradiating Ar gas to remove Au on the surface of the excitation electrode. .

The crystal device 1 described above is manufactured as follows.

First, the excitation electrodes 3 are formed on both main surfaces of the crystal substrate 30.
1, 33, and the crystal resonator 3 having the extraction electrodes 32, 34 extended to both main surfaces on one short side is prepared. At the same time, a pair of electrode pads 25, 25 are formed on the bottom surface of the base 2, that is, the surface of the flat substrate 21, and a seal ring 22 is formed on the surface around the opening of the cavity 20. A metal lid 6 is prepared. The surface of the seal ring 22 is Ni or Cr, and then Au.
Are formed by plating or the like.

Next, the electrode pad 2 formed separately
Anisotropic conductive resin paste serving as the anisotropic conductive adhesive member 4 is supplied and applied to Nos. 5 and 25 with a dispenser or the like. At this time, the anisotropic conductive resin paste supplied has a substantially hemispherical shape, and is formed so as to cover the inner surfaces of the seal ring 22 in the vicinity of the electrode pads 25, 25, respectively. .

Next, the crystal unit 3 is connected to the extraction electrode 32,
34. The bottom surface of the lower surface 34 is placed while being pressed so that it is positioned on the anisotropic conductive resin paste to which the outer corners are applied.

Next, the anisotropic conductive resin paste is hardened to bond and fix the substrate 2 and the crystal unit 3. Specifically, it is cured by applying heat.

After that, in a predetermined atmosphere, the seal ring 2
The metal lid 6 is placed on the plate 2, and both are hermetically sealed and joined by seam welding.

[0047]

As described above, according to the present invention, a base having a cavity formed by mounting and attaching a seal ring on a flat substrate is prepared. Further, an anisotropic conductive adhesive member is applied on each of the electrode pads separately formed on the lower surface of the cavity portion of the base body, and the outer deviation angle of the lower surface of each of the electrode pads and the pair of extraction electrodes of the crystal unit is offset. The parts are separated and joined.

By doing so, it is possible to provide a crystal device which can suppress the deterioration of the CI value and at the same time achieve thinning.

[Brief description of drawings]

FIG. 1 is a top view in which a lid of a crystal device of the present invention is omitted.

FIG. 2 is a sectional view taken along the line AA ′ of the crystal device of the present invention.

FIG. 3 is a cross-sectional view of conductive particles of an anisotropic conductive adhesive member used in the crystal device of the present invention.

FIG. 4 is a top view in which a lid of a conventional crystal device is omitted.

FIG. 5 is a sectional view of a conventional crystal device taken along line BB ′.

FIG. 6 is a top view showing a distribution of displacement of vibration with a lid of a conventional crystal device omitted.

[Explanation of symbols]

1 ... Crystal oscillator 2 ... Base 3 ... Crystal oscillator 4 ... Anisotropic conductive adhesive member 41 ... Resin 42 ... Conductive particles 6 ... Metal lid

Claims (3)

[Claims] 1. A crystal resonator having excitation electrodes formed on both main surfaces of a rectangular crystal substrate, and a pair of extraction electrodes connected to the excitation electrodes formed on the mounting main surface of the crystal substrate, and a flat plate shape. Of the insulating substrate, a metal frame body formed on the surface of the insulating substrate to form a cavity for accommodating the crystal unit, and formed on the surface of the insulating substrate surrounded by the metal frame body. A crystal device comprising: a base body composed of a pair of electrode pads; and a pair of anisotropic conductive adhesive members connecting the extraction electrodes of the crystal resonator and the electrode pads of the base body. 2. The crystal device according to claim 1, wherein an end surface of the crystal substrate is fixed to the metal frame via the anisotropic conductive adhesive member. 3. An external terminal electrode connected to a pair of electrode pads is led out to the bottom surface of the flat insulating substrate through a via hole penetrating the insulating substrate in the thickness direction. The described crystal device.