JP2003273268A - Sealing structure for electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing structure for a small-sized electronic component which can improve sealability without increasing the amount of an adhesive. <P>SOLUTION: The sealing structure for a small-sized electronic component comprises band-like electrodes 11 to 13 extended along the short side direction of a rectangular board formed on the upper surface of the rectangular board 10, electronic component elements 30, 40 connected between the electrodes, an opening in a cap 50 covering the element and adhered to the board and sealing the cap. In this structure, each electrode 11 to 13 is formed in a thickness of 50 μm or less, enlarged parts 12b, 13b are formed along the cap adhering part 14 of the board from at least one electrode toward other adjacent electrode and approached so that a gap between the enlarged part and the adjacent electrode is 0.5 mm or less. The cap adhering part of the board is covered with the electrodes except the gap between the enlarged part and the adjacent electrodes, and hence an adhesive 51 surely fills the gap of the electrodes. <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 sealing structure for electronic parts, and more particularly to a sealing structure suitable for surface mount electronic parts.

[0002]

2. Description of the Related Art Conventionally, as a surface mount type piezoelectric vibrator,
Some are shown in FIG. This piezoelectric vibrator includes an alumina substrate 1, on which an upper surface is formed with a first capacitance electrode 2 and two external electrodes 3 on both sides thereof. The electrodes 2 and 3 are formed on the peripheral surface of the substrate 1 in a spiral shape. A paste-like dielectric 4 is applied on the first capacitance electrode 2, and two second capacitance electrodes 5 are formed on the dielectric 4.
The main part thereof is formed so as to face the dielectric 4, and a part of the main part is electrically connected to the external electrode 3. Two capacitors are composed of the upper and lower capacitance electrodes 2 and 5 with the dielectric 4 interposed therebetween. A piezoelectric element 6 is attached on the second capacitance electrode 5 with a conductive adhesive or the like. After mounting the piezoelectric element 6 on the substrate 1, an alumina cap 7 is adhered to the substrate 1 so as to cover the piezoelectric element 6, and the inside is sealed. FIG. 2 shows the electric circuit.

[0003]

In the case of the surface mount type piezoelectric vibrator, the product is required to be liquid-tight because the cleaning process is performed at the time of mounting on the printed circuit board. The liquid tightness is secured by an adhesive 8 that bonds the substrate 1 and the cap 7, but as shown in FIG. 3, the electrodes 2 and 3 are formed on the substrate 1 with a thickness of about 1 to 50 μm. Therefore, there is a case in which a step due to the electrode thickness occurs on the adhesive surface of the cap, and the adhesive 8 cannot be fully rotated. Therefore, the sealing failure portion 9 as shown in FIG. 4 may be generated, and the cleaning liquid may enter the inside of the cap 7. As a countermeasure, there is a method of increasing the amount of the adhesive 8 to make it easier to fill the gap. In this case, the adhesive 8
Stick out from the substrate 1 or part of the adhesive 8 is applied to the piezoelectric element 6
There is also a possibility that it will adhere to the vibrating part of the above and adversely affect the characteristics of the piezoelectric element 6. Therefore, it is necessary to make the substrate 1 and the cap 7 large, and there is a drawback that the electronic component becomes large. As a method of reducing the step due to the electrode without increasing the amount of the adhesive 8, there is also a method of forming an insulating film on the cap bonding surface of the substrate and bonding the cap 7 thereon, but even in this case, depending on the film thickness. In some cases, the steps of the electrodes cannot be absorbed.

Therefore, an object of the present invention is to provide a small-sized sealing structure for electronic parts which can improve the sealing property without increasing the amount of the adhesive.

[0005]

In order to achieve the above object, the invention according to claim 1 forms a plurality of electrodes extending from an inner portion of the substrate to an outer peripheral edge portion on at least one surface of the substrate, and between the electrodes. In the electronic component in which the electronic component element is connected to the substrate, the opening of the cap that covers the electronic component element is adhered to the substrate with an epoxy adhesive, and the inside of the cap is sealed, the electrode has a conductive paste of 50 μm or less. It is printed on a thickness and fired, and an extension portion is formed on the electrode so that the electrode substantially covers the cap adhesion portion of the substrate, and an electrode adjacent to the extension portion in the cap adhesion portion and Interval is 0.2mm ~
The expanded portion and the adjacent electrode are formed close to each other so as to have a thickness of 0.5 mm.

According to a second aspect of the present invention, a plurality of strip-shaped electrodes extending along the short side direction of the substrate are formed on the upper surface of the rectangular substrate, and electronic component elements are connected between the electrodes. In an electronic component in which an opening of a cap covering an electronic component element is adhered to a substrate and the inside of the cap is sealed, the electrode is formed to have a thickness of 50 μm or less, and at least between the adjacent electrodes. An expansion portion is formed extending from one electrode toward the other adjacent electrode along the cap bonding portion of the substrate, and the expansion portion and the adjacent electrode are close to each other with a distance of 0.5 mm or less. The cap adhesion portion of the substrate is covered with the electrode except the gap between the expansion portion and the adjacent electrode, which is a sealing structure for electronic parts.

When the cap is adhered to the substrate, the cap intersects with the electrodes formed on the substrate, so that the adhesive flows into the gap between the electrodes. However, in the present invention, since the expanded portion is formed on the electrode so as to almost cover the cap adhesive portion,
The number of intersections between the cap and the electrode can be reduced. Moreover,
Since the gap between the expanded portion and the adjacent electrode in the cap adhesion portion is 0.5 mm or less, the gap between the cap and the substrate can be filled even with a small amount of adhesive, and the sealing performance is improved. Depending on the thickness of the electrode, the gap between the electrodes, which can be filled with the adhesive, changes, but the thickness of the electrode is 5
In the case of 0 μm or less, there is no great difference as long as the electrode interval is 0.5 mm or less.

According to the second aspect, as in the first aspect, the expanded portion formed on the electrode substantially covers the cap adhesive portion, so that the number of intersections between the cap and the electrode can be reduced. In particular, since the cap adhesion part of the substrate is covered by the electrode except for the gap between the expansion part and the adjacent electrode, the cap opening part and the electrode are adhered over substantially the entire circumference, and a small amount of adhesion is achieved. An electronic component having a good sealing property can be obtained even with the agent.

When a metal cap is used as the cap as in claim 7, an insulating film is formed on the cap bonding portion of the electrode in order to prevent the electrode and the cap from being electrically connected to each other. It is desirable to glue a cap on top. In this case, the step of the electrode is relaxed by the insulating film,
Further, since the cap is adhered thereon, the gap is surely filled.

[0010]

FIG. 5 shows a first embodiment of an electronic component according to the present invention. This electronic component is a built-in capacitance type piezoelectric oscillator provided with one oscillator and two capacitors used in a Colpitts type oscillation circuit, and its electric circuit is the same as in FIG.

The substrate 10 is a rectangular thin plate formed by sheet-molding or tablet-molding alumina ceramics, and has a thickness of 0.3 to 0.7 mm, for example. A ground electrode 11 is formed at the center of the upper surface of the substrate 10, and an input electrode 12 and an output electrode 13 are formed at both ends of the upper surface. These electrodes 11 to 13 are formed by a known method such as sputtering, vapor deposition, printing or thermal spraying. In this embodiment, Ag / Pd is taken into consideration in consideration of fixing strength and solderability.
A system baking type conductive paste was printed to a thickness of 50 μm or less (desirably 5 to 20 μm) and baked.
Of the electrodes 11 to 13, the earth electrode 11 is the substrate 10
It is formed in a strip shape in parallel with the short side of. On the other hand, the input electrode 12 and the output electrode 13 have strip-shaped portions (extended portions) 12a and 13a parallel to the short side of the substrate 10 and an extended portion (extended portion) 12b extending parallel to the long side toward the ground electrode 11. , 13
b are formed. The strip portions 12a and 13a are extended to the vicinity of the short side edge of the substrate 10. The strip-shaped portions 12a and 13a and the extension portions 12b and 13b substantially cover the adhesive portion 14 of the cap 50 described later. The extensions 12b and 13b and the ground electrode 11 are close to each other, and the distance d between them is set to 0.5 mm or less. Both ends of the electrodes 11 to 13 are drawn out to a concave through hole portion 10a formed in a long side portion (outer edge portion) of the substrate 10, and the substrate 10 is formed through electrodes formed on the inner surface of the through hole portion 10a. Is connected to the lower electrode.

A cap adhesive portion 14 on the substrate 10
A frame-shaped insulating film 15 is formed with a constant thickness on a portion corresponding to (shown by a broken line in FIG. 5). As the material of the insulating film 15, resin-based or glass-based paste is used. The method of forming the insulating film 15 includes printing, transfer, dispensing, etc., but a pattern printing method capable of accurately controlling the layer thickness is desirable. Insulation film 1
The thickness of 5 is preferably, for example, about 20 to 40 μm so as to alleviate the step due to the electrodes 11 to 13 and ensure sufficient insulation between the cap 50 and the electrodes 11 to 13 described later. . The insulating film 15 is baked or cured after printing.

On the substrate 10, a material in which a resonator element 30 and a capacitor element 40 are laminated and integrated by a material 20 to 22 having both conductive and adhesive functions such as a conductive adhesive is fixed by adhesion. Has been done. The oscillator element 30 of this embodiment is a thickness-shear vibration mode oscillator element. That is, as shown in FIG. 6, the electrodes 32 are formed from one end side of the surface of the piezoelectric substrate 31 to a region of about ⅔,
The electrode 33 is formed over the area of about 2/3 from the other end of the back surface. One end of each of the electrodes 32 and 33 is a piezoelectric substrate 31.
And an intermediate portion therebetween with a space between them to form a vibrating portion. The other ends 32a and 33a of the electrodes 32 and 33 extend around both ends of the piezoelectric substrate 31 to the other side.

Further, as shown in FIG. 7, two capacitor elements 40 extend from both ends toward the center on the surface of a dielectric substrate (for example, a ceramic substrate) 41 having the same length and width as the oscillator element 30. Individual electrodes 42, 43 are formed, and one common electrode 44 facing the individual electrodes 42, 43 is formed on the back surface. Capacitance parts are formed. In addition, the end portions 42a and 43a of the individual electrodes 42 and 43 wrap around to the back surface side through both end surfaces of the dielectric substrate 41.

The back surface of the oscillator element 30 and the capacitor element 4
The surface of No. 0 is adhesively fixed at both ends by materials 23 and 24 having both conductive and adhesive functions such as a conductive adhesive. At this time, a predetermined vibration space is formed between the vibrating portion of the oscillator element 30 and the capacitor element 40 due to the thickness of the materials 23 and 24. In this way, one electrode 33 of the oscillator element 30 and one individual electrode 42 of the capacitor element 40 are connected, and the other electrode 3
2 and the other individual electrode 43 are connected. Damping materials 25 and 26 made of resin or the like for frequency adjustment are applied to both ends of the surface of the oscillator element 30.

After the oscillator element 30 and the capacitor element 40 are bonded and integrated, the back surface side of the capacitor element 40 is bonded to the substrate 10 with the materials 20 to 22, and one end 42a of one individual electrode 42 of the capacitor element 40 is bonded. Is the input electrode 12, and the end portion 43a of the other individual electrode 43 is the output electrode 1
3, the common electrode 44 is connected to the ground electrode 11, respectively.

The cap 50 has an opening bonded to the substrate 10 with an adhesive 51 so as to cover the oscillator element 30 and the capacitor element 40. As the material of the cap 50, there are ceramics such as alumina, resin, and metal, but in this embodiment, a metal material press-formed into a U-shaped cross section was used in order to ensure downsizing of the product and dimensional accuracy. The selection of the metal material is arbitrary as long as product strength and adhesiveness are obtained, and for example, aluminum alloy, nickel silver, 42Ni alloy, etc. can be used. An epoxy adhesive was used as the adhesive 51, which was applied to the bottom surface of the opening of the cap 50, and then adhered onto the insulating film 15 and cured.

In the capacitor built-in type piezoelectric oscillator constructed as described above, the electrodes 11 to 13 formed on the substrate 10 are formed.
Has a step due to its thickness, and the insulating film 15 is formed on the step.
Even if the cap is formed, a gap may occur between the cap 50 and the insulating film 15. However, since the gap between the electrodes 11 to 13 in the cap bonding portion 14 is set to 0.5 mm or less, the above gap is very small, and as shown in FIGS. Can be fully filled. Therefore, sufficient sealing performance can be obtained.

The following table shows the relationship between the electrode spacing and the sealing failure rate obtained by the gross leak test. The test conditions are that the electrode thickness is 10 to 15 μm, the outer size of the cap 50 is 6.7 × 2.2 mm, and the plate thickness is 0.15.
mm, and 0.7 mg of the adhesive 51 having a viscosity of 30,000 to 65,000 CPS was applied per cap.

[0020]

[Table 1]

According to this, it is understood that no sealing failure occurs when the electrode interval is 0.5 mm or less. The above-mentioned test was conducted when the thickness of the electrode was 10 to 15 μm, but the same result as above was obtained when the thickness of the electrode was 50 μm or less. Also, because of printing, the electrode spacing must be at least 0.2 mm. It was omitted when it was less than 0.2 mm.

In the above-mentioned embodiment, an example in which a metal cap is used as the cap is shown, but in FIGS. 10 and 11, a non-metal cap 52 such as alumina is used. The parts other than the cap 52 were the same as those in FIG. In this case, since the cap 52 itself is non-conductive,
It is not necessary to form an insulating film on the substrate 10 and the cap 5
2 is directly bonded onto the substrate 10. In this case, the thickness of the electrodes 11 to 13 is likely to be affected by the absence of the insulating film. However, if the distance d between the electrodes 11 to 13 is set to 0.5 mm or less, the adhesive 51 causes the adhesive between the cap 52 and the substrate 10. It was possible to fill in the gaps, and a good sealing effect was obtained.

FIG. 12 shows another embodiment of the substrate 60. In this embodiment, the input from the ground electrode 61, the output electrodes 62, 6
The extended portion (extended portion) 61a is extended in three directions, and the electrodes 61 to 63 substantially cover the cap bonding portion 64 (shown by a broken line). Also in this case, the distance d between the extension 61a and the input / output electrodes 62, 63 may be set to 0.5 mm or less.

The end shape of the extended portion (extended portion) of the electrode in the cap bonding portion may be such that the electrodes 71 and 72 are inclined with respect to the side edges of the substrate 70 as shown in FIG. 13, and as shown in FIG. It may be bent stepwise. In addition, 71a, 7
2a is an extension of the electrodes 71, 72. In these cases, the gap portion between the extension portions 71a and 72a intersects the cap opening portion obliquely or in a crank shape, so that the sealing width is increased and the sealing performance is improved. In any case, it is necessary to set the gap distance d to 0.5 mm or less.

The present invention is not limited to the built-in capacitance type oscillator having the oscillator element and the capacitor element as in the above embodiment,
It can also be applied to a resonator with a built-in capacitor having a capacitor formed on a substrate. Furthermore, the present invention can be applied to electronic components such as oscillators, filters, and circuit modules that do not have a built-in capacitor.

[0026]

As is apparent from the above description, claim 1
According to the invention described in (1), when electrodes having a thickness of 50 μm or less are formed on the substrate by printing and firing, the electrodes are provided with an expansion portion so as to substantially cover the cap adhesive portion, and the cap adhesive portion of the substrate is formed. Distance between electrodes is 0.2mm
Since the thickness is 0.5 mm, the number of places where the cap and the electrode intersect is reduced, and even a small amount of adhesive can fill the step due to the electrode thickness, and the sealing property between the cap and the substrate is improved. Therefore, it is not necessary to increase the size of the substrate or the cap, and a small sealed electronic component can be obtained.

According to the invention of claim 2, 50 μm
Between the electrodes having the following thickness, an extended portion extending along the cap adhesive portion of the substrate is formed, the distance between the extended portion and an adjacent electrode is set to 0.5 mm or less, and the cap adhesive portion of the substrate is used as the extended portion. Since the electrode is covered except for the gap between the adjacent electrodes, the opening of the cap and the electrode are adhered over substantially the entire circumference, and an electronic component having a good sealing property can be obtained even with a small amount of adhesive.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a conventional piezoelectric vibrator with a built-in capacitor.

2 is an electric circuit diagram of the piezoelectric vibrator shown in FIG. 1. FIG.

FIG. 3 is a cross-sectional view of an adhesive portion of the piezoelectric vibrator shown in FIG.

FIG. 4 is an enlarged view of part A of FIG.

FIG. 5 is an exploded perspective view of a piezoelectric oscillator with a built-in capacitor, which is an example of an electronic component according to the present invention.

6 is a front and back view of an oscillator element used in the piezoelectric oscillator shown in FIG.

7 is a front and back view of a capacitor element used in the piezoelectric oscillator shown in FIG.

FIG. 8 is a perspective view of the piezoelectric oscillator of FIG. 5 in an assembled state.

9 is a sectional view taken along line BB of FIG.

FIG. 10 is a second piezoelectric oscillator with a built-in capacitor according to the present invention.
It is a perspective view of an Example.

11 is a cross-sectional view taken along the line CC of FIG.

FIG. 12 is a perspective view of a substrate according to a third embodiment of the present invention.

FIG. 13 is a partial plan view of a fourth embodiment showing the end shape of the electrode according to the present invention.

FIG. 14 is a partial plan view of a fifth embodiment showing the end shape of the electrode according to the present invention.

[Explanation of symbols]

10 substrates 11 Earth electrode 12 input electrodes 12a Band-shaped part (expansion part) 12b Extension (extension) 13 Output electrode 13a band-shaped part (expansion part) 13b Extension (extension) 14 Cap adhesive part 15 Insulating film 30 oscillator element 40 Capacitor element 50 cap 51 adhesive

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junji Koyama             2-10-10 Tenjin, Nagaokakyo, Kyoto Stock             Murata Manufacturing Co., Ltd.

Claims (7)

[Claims] 1. A plurality of electrodes are formed on at least one surface of a substrate, the electrodes extending from an inner portion of the substrate to an outer peripheral portion thereof. The electronic component elements are connected between the electrodes, and an opening portion of a cap for covering the electronic component elements is epoxy. In an electronic component that is adhered to a substrate with a system adhesive and the inside of a cap is sealed, the electrode is printed with a conductive paste to a thickness of 50 μm or less,
This is fired, and an extension portion is formed on the electrode so that the electrode substantially covers the cap adhesion portion of the substrate, and the gap between the extension portion and the adjacent electrode in the cap adhesion portion is 0. A sealing structure for an electronic component, characterized in that the expanded portion and an adjacent electrode are formed close to each other so as to have a thickness of 2 mm to 0.5 mm. 2. A plurality of strip-shaped electrodes extending along the short side direction of the substrate are formed on the upper surface of a rectangular substrate, the electronic component elements are connected between the electrodes, and a cap for covering the electronic component elements is formed. In an electronic component in which the opening is adhered to the substrate and the inside of the cap is sealed, the electrode is formed to have a thickness of 50 μm or less, and at least one electrode is adjacent to the other electrode between the adjacent electrodes. Toward the electrode of the substrate, an expansion portion extending along the cap adhesion portion of the substrate is formed, and the expansion portion and the electrode adjacent to each other are close to each other so that the distance between them is 0.5 mm or less. The sealing structure for an electronic component, wherein the adhesive portion is covered with an electrode except for a gap between the extension portion and an electrode adjacent to the adhesive portion. 3. The electronic component sealing structure according to claim 2, wherein an earth electrode is formed at the center, an input electrode is formed at one end, and an output electrode is formed at the other end on the upper surface of the substrate.
The extension portion is formed from the input electrode and the output electrode toward the ground electrode, and the extension portion and the ground electrode are close to each other such that the distance between them is 0.5 mm or less. A sealing structure for an electronic component, characterized in that it is covered by the ground electrode, the input electrode, and the output electrode except for a gap between the expansion portion and the ground electrode. 4. The electronic part sealing structure according to claim 2, wherein a ground electrode is formed in the center, an input electrode is formed on one end side, and an output electrode is formed on the other end side on the upper surface of the substrate.
The extension portion is formed from the ground electrode toward the input electrode and the output electrode, and the extension portion and the input electrode,
And the gaps between the extension and the output electrode are close to each other so as to be 0.5 mm or less, and the cap bonding portion includes a gap between the extension and the input electrode and a gap between the extension and the output electrode. The sealing structure for electronic parts is characterized by being covered by the ground electrode, the input electrode, and the output electrode except the above. 5. The electronic component sealing structure according to claim 2, wherein a ground electrode is formed at the center, an input electrode is formed at one end, and an output electrode is formed at the other end on the upper surface of the substrate.
The extended portion is formed such that a portion extending from the ground electrode toward the input electrode and the output electrode and a portion extending from the input electrode and the output electrode toward the ground electrode are opposed to each other, and the space between the extended portions is large. Are close to each other so as to be 0.5 mm or less, and the cap adhesive portion is covered with the ground electrode, the input electrode, and the output electrode except for the gap between the expansion portions. Sealing structure for electronic components. 6. The electronic component sealing structure according to claim 5, wherein a gap that is inclined with respect to a side edge of the substrate or is bent in a crank shape is formed between the expanded portions. An encapsulation structure for electronic parts, which is characterized in that 7. The electronic component sealing structure according to claim 1, wherein the cap is a metal cap, and an insulating film covering the electrode is formed on a cap bonding portion of the substrate. A sealing structure for electronic parts, wherein a cap is adhered on the insulating film.