JPH0714721U - Piezoelectric resonator - Google Patents

Abstract

(57) [Summary] [Object] To provide a piezoelectric resonator capable of sealing a lid stably and surely regardless of the surface structure of a capacitance substrate. [Structure] The present invention has a piezoelectric element 2 on a rectangular capacitive substrate 1 on which at least capacitive components C ₁ and C ₂ connected to the piezoelectric element ₂ are formed, and four side bonding surfaces 35a to 35d. This is a piezoelectric resonator that is housed and sealed with a housing-shaped lid 3. Then, the joint surfaces 35a to 35d of the lid 3 are
A recessed portion 36 is formed whose central portion in the lengthwise direction is recessed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a chip type piezoelectric resonator suitable for surface mounting.

[0002]

[Prior art]

Piezoelectric resonators using piezoelectric elements are widely used as resonators for clock pulse oscillators of microcomputers. The piezoelectric resonator is a component of the piezoelectric element X and the capacitance components C ₁ and C ₂ connected to both ends of the piezoelectric element, which is a dotted line portion of the oscillation circuit in FIG.

Conventionally, as shown in FIG. 8, it is composed of a capacitive substrate 1 on which capacitive components C ₁ and C ₂ are formed, a piezoelectric element 2, and a housing-like lid body 7 with an opening at the joint surface. ing.

The capacitive substrate 1 is made of a dielectric ceramic such as barium titanate, and various capacitive electrode patterns are formed to form _two capacitive components C ₁ and C ₂ . For example, the strip-shaped capacitance electrode patterns 11a, 12a, 13a are formed on one main surface, the strip-shaped capacitance electrode patterns 11b, 12b, 13b are formed on the other main surface, and the capacitance electrodes are formed on the end faces. Conductor films are formed so as to connect the patterns 11a and 11b, 12a and 12b, and 13a and 13b.

As a result, the capacitance component C ₁ is generated between the capacitance electrode patterns 11a and 13a (11b and 13b), and the capacitance component C ₂ is generated between the capacitance electrode patterns 12a and 13a (12b and 13b).

The capacitance electrode patterns 11b and 12b on the other main surface act as input / output terminal electrodes of the piezoelectric resonator, and the capacitance electrode pattern 13b acts as a ground-side terminal electrode of the piezoelectric resonator. The electrode patterns 11a and 12a act as connection electrodes for the piezoelectric element 2. Therefore, when the piezoelectric element 2 is electrically connected to the capacitive electrode patterns 11a and 12a, the conductive adhesives 5 and 5 flow out to the capacitive electrode patterns 13a, and the capacitive electrode patterns 13a and the capacitive electrode patterns 11a and 12a. Insulating film 14 is formed on capacitor electrode pattern 13a including between both electrode patterns so as to prevent short circuit between and.

Further, the piezoelectric element 2 is composed of a substrate 20 in which a piezoelectric ceramic is formed in a strip shape, and vibration electrodes 21 and 21 extending in different longitudinal directions are formed on both main surfaces thereof. .

The lid 7 is made of ceramic or the like, and has a recess 71 capable of accommodating the piezoelectric element 2, and a step for mounting the piezoelectric element 2 on inner walls of the recess 71 facing each other in the longitudinal direction. Portions 72 and 73 are formed. This shape is formed by pressing and firing ceramic powder.

In the assembly of such a piezoelectric resonator, the piezoelectric element 2 is placed on the stepped portions 72 and 73 of the lid body 7 via the conductive adhesives 5 and 5, and the piezoelectric element 2 is placed inside the lid body 7. 2 is accommodated, and the lid 7 and the capacitance substrate 1 are bonded to each other via the sealing member 4. At this time, the capacitive electrode patterns 11a and 12a on the capacitive substrate 1 and the conductive adhesives 5 and 5 on both ends of the piezoelectric element 2 are connected.

[0010]

[Problems to be solved by the device]

 Here, it is ideal that the joint surfaces around the opening of the lid body 7 (two long side joint surfaces and two short side joint surfaces) are formed as one plane. However, in the process of producing this lid 3, especially on the long side, due to the difference in the density distribution of the powder when pressing the ceramic powder and the difference in the shrinkage rate during firing due to the shape. In the above, a warp occurs in a convex shape about 10 to 30 μm around the center portion in the length direction.

Moreover, the capacitor substrate 1 joined to the central portion where the warp is remarkable is provided with the capacitor electrode pattern 13a extending in the short side direction of the surface of the capacitor substrate 1 and the insulating film 14 adhered to the upper surface thereof. Therefore, even if the thickness of the sealing member 4 is set to 30 μm or more, for example, even if it is set to 30 μm or more, the short side of the lid body The bonding surface of the capacitor substrate 1 is widened, and the gap between the bonding surface on one short side and the capacitor substrate 1 is widened to about twice the warp due to the pressure applied during sealing. There is. As a result, for example, even if sealing can be performed on the bonding surface on one short side of the lid 7, the bonding width of the sealing member 4 can be reduced on the bonding surface on the other short side, or no bonding can be performed at all. Some parts cannot be formed, resulting in extremely low sealing reliability.

The present invention has been devised in view of the above problems, and an object thereof is to stably and reliably seal a lid body regardless of the surface structure of the capacitive substrate and the warp of the lid body. It is to provide a piezoelectric resonator that can be stopped.

[0013]

[Means for Solving the Problems]

 According to the present invention, a piezoelectric element is housed in a container that is composed of at least a rectangular capacitive substrate on which a capacitive component connected to the piezoelectric element is formed and a bowl-shaped lid joined to the capacitive substrate. In the piezoelectric resonator, the lid has a concave portion that is deepened toward a central portion on a joint surface that is joined to at least a long side of the rectangular capacitive substrate.

[0014]

[Action]

 In the piezoelectric resonator of the present invention, regardless of the structure of the capacitive substrate, the joint surface on at least the long side of the lid has a recessed portion that is recessed at the center in the longitudinal direction. The portion where the distance between the lid and the joint surface is the minimum is substantially the area around the opening of the lid and including the four corners of the joint surface.

Therefore, even if pressure is applied to the capacitance substrate and the lid at the time of joining and the pressure is non-uniform, the gap between the capacitance substrate and the lid does not substantially increase unintentionally. The sealing member supplied to the joint surface around the opening of the lid can stably and reliably join the both.

The shape of the joint surface of the lid body is such that the center of the joint surface in the longitudinal direction of the joint surface is still taken into consideration, even when a normal warp is taken into consideration when pressing the lid body of ceramic powder. This can be achieved by performing press work so that the parts are recessed.

[0017]

【Example】

 Hereinafter, the piezoelectric resonator of the present invention will be described in detail with reference to the drawings. FIG. 1A is a side view of the piezoelectric resonator of the present invention on the long side, FIG. 1B is a side surface on the short side, and FIG. 2 is a sectional view corresponding to FIG. The same parts as those in FIG. 8 are designated by the same reference numerals.

In the figure, in the piezoelectric resonator, the capacitance substrate 1 and the lid 3 are joined to each other via a sealing member 4 on the joining surface of the lid 3 to form a container, and the piezoelectric substrate is placed in the container. Element 2 is stored.

The capacitance substrate 1 is a dielectric substrate 10 made of a dielectric ceramic material such as barium titanate-based, calcium titanate-based, or alumina, and a plurality of capacitance electrode patterns 11 a formed on both main surfaces of the substrate 10. .About.13a and 11b to 13b.

As shown in FIG. 3, a capacitor connected to one electrode 21 of the piezoelectric element 2 is provided on the main surface of the dielectric substrate 10 in order to derive the capacitance components C ₁ and C ₂ of FIG. An electrode pattern 11a, a capacitance electrode pattern 12a connected to the other electrode 22, and a capacitance electrode pattern 13a having a ground potential are formed. Capacitor electrode patterns 11b to 13b are formed on the main surface of the back side of the substrate 1 corresponding to the capacitance electrode patterns 11a to 13a. The capacitor electrode patterns 11a and 11b are connected via the conductor film on the end face of the substrate 1, and the capacitor electrode patterns 12a and 12b and the capacitor electrode patterns 13a and 13b have the same structure.

Further, an insulating coating 14 is formed on the capacitance electrode pattern 13a so as to cover the space between the capacitance electrode patterns 11a and 13a and the space between the capacitance electrode patterns 12a and 13a. The insulating coating 14 has cutouts 15 and 16 so that the piezoelectric element 2 and the capacitive electrode patterns 11a and 12a are surely connected to each other via the conductive adhesives 5 and 5. And 13a and 12a and 13a are prevented from being short-circuited so that the predetermined capacity can be reliably derived.

The electrodes 11a to 13a and 11b to 13b are formed by printing a conductive paste made of a material such as silver or silver-palladium on the front surface and the back surface of the substrate 1 by screen printing and baking.

As shown in FIG. 4, the piezoelectric element 2 is composed of a strip-shaped substrate 20 of a piezoelectric ceramic, and electrodes 21 and 22 extending to the end portions of the substrate 20 different from each other are formed on both main surfaces thereof. Has been formed.

The lid 3 is made of a ceramic such as alumina, and as shown in FIG. 5, it has a bowl-like shape in a plan view having an opening 31 formed on the surface serving as a joint surface, and is substantially rectangular. The four sides around the opening 31, that is, the two long side peripheral surfaces (joint surfaces) 35a and 35c on the longitudinal side and the short side peripheral surfaces (joint surfaces) 35b and 35d orthogonal to the three sides are capacitances. The four ends of the substrate 1 are joined via the sealing member 4. Further, a hollow portion 32 for housing the piezoelectric element 2 is formed from the opening 31 to the inside.

Step portions 33 and 34 are formed in the hollow portion 32 at portions corresponding to both end portions of the piezoelectric element 2.

The shape of the opening 31 is slightly larger than that of the piezoelectric element 2, and in particular, the portions corresponding to the step portions 33 and 34 are formed slightly larger than the width of the piezoelectric element 2.

Here, in the present invention, the joint surfaces 35a to 35d are not uniform flat surfaces, but a recessed portion 36 that is recessed inward is formed. The recess 36 is recessed by 10 to 30 μm near the center of each side. In FIG. 5, the concave portion 36 is formed only in the joint surfaces 35a and 35b on the long side, and the shape of the concave portion 36 is curved so as to gradually become deeper toward the central portion.

When assembling the piezoelectric resonator, first, a sealing member 4, for example, a thermosetting resin such as an epoxy resin is applied to the joint surfaces 35 a to 35 d of the lid 3. The sealing member 4 is applied with a thickness of at least 10 to 30 μm or more so as to be able to absorb at least the depression of the recess 36.

Next, the conductive adhesives 5 and 5, for example, a thermosetting resin having conductive powder such as Ag, is supplied to the stepped portions 33 and 34 of the lid body 3, and the inside of the conductive adhesives 5 and 5b is supplied. Then, the piezoelectric element 2 is placed on the step portions 33 and 34 so as to embed the end portion thereof. At this time, the tip portions of the conductive adhesive materials 5 and 5 are made to be at the same height as or higher than the sealing member 4 applied to the joint surface of the lid body 3.

Next, the capacitance plate 1 is placed on the joint surfaces 35a to 35d of the lid body 3 so that the main surface side on which the capacitance electrodes 11a to 13a are formed faces each other. At this time, one electrode 21 of the piezoelectric element 2 is attached to the capacitive electrode pattern 11a exposed from the insulating coating 14, and the other electrode 22 of the piezoelectric element 2 is attached to the capacitive electrode pattern 12a exposed from the insulating coating 14, respectively. Connect via 5, 5.

Thereafter, heat treatment is performed while applying a predetermined pressure from the capacitive substrate 1 to the lid body 3 side to completely cure the sealing member 4, and at the same time, to cure the conductive adhesive materials 5 and 5. A piezoelectric resonator in which 2 and the capacitor electrode patterns 11a and 12a are electrically connected and the lid 3 and the substrate 1 are hermetically sealed is completed.

As a result, the piezoelectric element 2 is connected to the capacitive substrate 1 on which the _two capacitive components C ₁ and C ₂ are formed, and the parts indicated by the dotted line in the circuit diagram of FIG. 7 are achieved.

As described above, according to the present invention, since the concave portion 36 is formed in the vicinity of the central portion of the joint surfaces 35a, 35c on the long side of the lid 3, the lid 3 is formed as shown in FIG. The thickness of the sealing member 4 between the body 3 and the capacitive substrate 1 is the smallest near both ends thereof.

Therefore, the capacitive electrode patterns 11a to 13a formed on the main surface of the capacitive substrate 1 on the bonding surface side are formed in a band-shaped pattern so as to traverse the longitudinal direction of the capacitive substrate 1, and the capacitive electrode patterns 11a to 13a are formed. Even if three-dimensionally intersects the bonding surfaces 35a, 35c on the long side of the lid 3 at the end of the, the thickness of the capacitive electrode patterns 11a to 13a and the thickness of the insulating coating 14 are substantially formed in the recess 36. (Concave and convex of the structure on the substrate) can be absorbed, and the sealing by the sealing member 4 becomes reliable.

In addition, since the concave portions 36 in which the joint surfaces 35 a and 35 c are recessed are formed in advance, the joint surfaces 35 a and 35 d come into contact with the capacitor electrode patterns 11 a to 13 a and the insulating coating 14, respectively. Since there is substantially no gap that exceeds the thickness of the sealing member 4 generated in 35b and 35d, the sealing reliability is improved.

In forming the lid body 3, the concave portion 36 as described above is formed even when a warp protruding to the outside is generated at the time of pressing the ceramic powder, particularly at the bonding surfaces 35 a and 35 d on the long side. After the firing, the recesses 36 are formed by performing processing in consideration of forming the recesses 36.

If a recess 36 is formed such that the central portions of the joint surfaces 35 a and 35 c of the lid body 3 in the longitudinal direction are recessed from the joint surface, as shown in FIG. Even when the capacitive electrode patterns 11a to 13a and the insulating coating 14 are formed, and also in the capacitive substrate 1 having another structure shown in FIGS. 6A and 6B, the capacitive electrode pattern of the capacitive substrate 1 is formed. It is possible to sufficiently absorb the uneven shape of the substrate surface due to the formation of the insulating coating and to completely seal the entire bonding surfaces 35a to 35d of the lid body 3 through the capacitive substrate 1 and the sealing member 4. .

The structure of the capacitor substrate of FIG. 6A will be described. Two capacitor electrode patterns 11d and 11e connected to the piezoelectric element 2 are formed on the front surface side of the dielectric substrate 10, and the back surface side thereof is formed. Capacitor electrode patterns 11e and 12e serving as input / output electrodes connected to the capacitor electrode patterns 11d and 12d through the end face of the substrate, and a ground-side capacitor electrode pattern 13e shown by a dotted line are formed. Two capacitance components, C ₁ and C _2, are generated by the capacitance electrode patterns 11d and 13e and the capacitance electrode patterns 11d and 13e which face each other through the thickness of the dielectric substrate 10, respectively.

The structure of the capacitor substrate of FIG. 6B will be described. On the surface side of the dielectric substrate 10, two capacitor electrode patterns 11f, 12f connected to the piezoelectric element 2 and having a comb tooth shape, and Comb-shaped floating capacitance electrode patterns 13f are formed between the capacitance electrode patterns 11f and 12f, and the capacitance electrode patterns 11f and 12f and the substrate end face are provided on the back surface side of the dielectric substrate 10. Capacitance electrode patterns 11g and 12g, which serve as input / output electrodes to be connected to each other, and a ground-side capacitance electrode pattern 13g, which is formed at a portion corresponding to the intersection of the comb teeth, are formed.

The capacitance component is the capacitance generated by the comb teeth of the capacitance electrode pattern 11f and the floating capacitance electrode pattern 13f, and the capacitance generated by the comb teeth of the capacitance electrode pattern 12f and the floating capacitance electrode pattern 13f. And a capacitance generated between the capacitance electrode pattern 11f and the capacitance electrode pattern 13g facing each other through the thickness of the dielectric substrate 20 and a capacitance generated between the capacitance electrode pattern 12f and the capacitance electrode pattern 13g. Further, a capacitance generated between the floating electrode capacitance pattern 13f and the capacitance electrode pattern 13g is generated. These five capacitances are combined with each other, and in terms of an equivalent circuit, two capacitance components C ₁ shown in FIG. , C ₂ can be derived.

In the above description, the joint surfaces 35b, 35d on the short side are formed by a uniform plane, but the joint surfaces 35b, 35d on the short side are prevented from warping outward due to firing. It is also useful to form a recessed portion in order to do so. Further, when the electrode patterns 11a and 12a are formed at the short-side ends of the capacitance substrate 1 where the bonding surfaces 35b and 35d are bonded, the recesses must be positively formed.

[0042]

[Effect of device]

 As described above, in the present invention, since the recessed concave portion is formed in the vicinity of the central portion of the joint surface of the lid body in the longitudinal direction, it is possible to substantially prevent outward warpage that occurs during the manufacturing process of the lid body. In addition, the unevenness due to the thickness of various patterns formed on the end of the capacitor substrate can be absorbed, the sealing between the lid and the substrate is ensured, and the sealing reliability is dramatically improved. Improve to.

[Brief description of drawings]

FIG. 1 is a side view of a piezoelectric resonator of the present invention, (a) is a side view of a long side, and (b) is a side view of a short side.

2 is a sectional view of the piezoelectric resonator of the present invention, and FIG.
It corresponds to (a).

FIG. 3 is an external perspective view of a capacitor substrate using the piezoelectric resonator of the present invention.

FIG. 4 is an external perspective view of a piezoelectric element using the piezoelectric resonator of the present invention.

[Part 5] It is an external perspective view of the opening side of the lid using the piezoelectric resonator of the present invention.

6A and 6B are schematic views of another capacitance substrate.

FIG. 7 is an equivalent circuit diagram of an oscillator circuit.

FIG. 8 is a sectional view of a conventional piezoelectric resonator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Capacitance substrate 11a-13a ... Capacitance electrode pattern 11b-13b ... Capacitance electrode pattern 14 ... Insulating film 2 ... Piezoelectric element 21, 22 ... Electrode 3 Lid 31 Opening 32 Hollow 33, 34 Step 4 Sealing member 5 Conductive adhesive

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[Procedure amendment]

[Submission date] February 10, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a side view of a piezoelectric resonator of the present invention, (a) is a side view of a long side, and (b) is a side view of a short side.

2 is a sectional view of the piezoelectric resonator of the present invention, and FIG.
It corresponds to (a).

FIG. 3 is an external perspective view of a capacitor substrate used in the piezoelectric resonator of the present invention.

FIG. 4 is an external perspective view of a piezoelectric element used in the piezoelectric resonator of the present invention.

FIG. 5 is an external perspective view of the opening side of the lid used in the piezoelectric resonator of the present invention.

6A and 6B are schematic views of another capacitance substrate.

FIG. 7 is an equivalent circuit diagram of an oscillator circuit.

FIG. 8 is a sectional view of a conventional piezoelectric resonator.

[Description of Reference Signs] 1 ... Capacitance substrate 11a to 13a ... Capacitance electrode pattern 11b to 13b ... Capacitance electrode pattern 14 ... Insulating coating 2 ... Piezoelectric element 21, 22 ... Electrode 3 ... Lid 31 ... Opening 32 ... Hollow 33, 34 ... Step 4 ... Sealing member 5 ... Conductive adhesion Material

Claims (1)

[Scope of utility model registration request] 1. A piezoelectric element is housed in a container which is composed of at least a rectangular capacitive substrate on which a capacitive component connected to the piezoelectric element is formed, and a bowl-shaped lid joined to the capacitive substrate. In the piezoelectric resonator according to the present invention, the lid has a concave portion that is deepened toward a central portion in a joint surface that is joined to at least a long side of the rectangular capacitive substrate.