JP3686461B2 - Piezoelectric vibrator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric vibrator having a configuration in which a piezoelectric vibrating piece or a semiconductor element is fixed to a substrate with an adhesive, and a piezoelectric oscillator.
[0002]
[Prior art]
A conventional piezoelectric vibrator and a piezoelectric oscillator will be described using a piezoelectric vibrator as an example with reference to the drawings.
[0003]
FIG. 6 is a perspective view showing a conventional piezoelectric vibrator. The substrate 61 is an insulator such as ceramic, and a conductive pattern 63 is formed on the substrate 61 by printing or the like.
[0004]
In the piezoelectric vibrating piece 65, excitation electrodes 66 are formed of metal such as Ag on the front and back surfaces.
[0005]
The piezoelectric vibrating piece 65 is fixed by a conductive adhesive 67 applied to a part of the conductive pattern 63 to adjust the frequency.
[0006]
The substrate 61 is sealed with a sealing material 64 such as low melting point glass or epoxy resin adhesive provided in advance on the edge of the lid 62.
[0007]
[Problems to be solved by the invention]
However, in the conventional technology, moisture intrusion into the package from the joint between the lid and the substrate (seal material in the conventional technology example) occurs, and the moisture oxidizes the excitation electrode of the piezoelectric vibrating piece, and the frequency change or There was a problem that characteristics such as an increase in impedance of the piezoelectric vibrator deteriorated.
[0008]
Further, in the case of the piezoelectric oscillator, the semiconductor element in the package has a problem that leakage occurs due to the influence of moisture and current consumption increases.
[0009]
Japanese Utility Model Laid-Open No. 2-113430 describes that a moisture absorbent and an epoxy resin adhesive are mixed and applied to a part of a package as a measure for preventing deterioration of characteristics due to moisture. However, as in the example of Japanese Utility Model Laid-Open No. 2-113430, a mixture of a moisture absorbing agent that absorbs moisture and an epoxy resin adhesive is applied to a part of the package, so that the region to which this mixture is applied is included in the package. Therefore, it is difficult to reduce the size and thickness of the package. In addition, a process, machine and apparatus for preparing and applying the mixture are required, which has been a factor in increasing costs.
[0010]
[Means for Solving the Problems]
The piezoelectric vibrator of the present invention is a flat plate piezoelectric vibrator in which a piezoelectric vibrating piece having a silver electrode is sealed with a substrate and a lid, and a thermosetting conductive adhesive and a hygroscopic agent are paired in a volume ratio. The piezoelectric vibrating piece is electrically connected to a conductive pattern provided on the substrate and is fixed to the substrate with an adhesive mixed at a ratio of 0.3 to 1.
[0011]
Another vibrator of the present invention is a flat piezoelectric vibrator in which a piezoelectric vibrating piece having a silver electrode is sealed with a substrate and a lid, the first conductive adhesive containing no hygroscopic agent, Second conductive adhesive in which a conductive pattern provided on the substrate and the piezoelectric vibrating piece are in contact with each other, and a thermosetting conductive adhesive and a hygroscopic agent are mixed at a volume ratio of 1: 0.3 to 1. An agent is in contact with the first conductive adhesive and the piezoelectric vibrating piece, and the piezoelectric vibrating piece is electrically connected to a conductive pattern provided on the substrate and fixed to the substrate.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The piezoelectric vibrator of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a perspective view showing a first embodiment of the piezoelectric vibrator of the present invention, and FIG. 2 is a cross-sectional view showing details of a fixing portion between the piezoelectric vibrating piece and the substrate of FIG.
[0021]
The substrate 1 is an insulator such as ceramic, and a metal such as tungsten is printed on the substrate 1 and the conductive pattern 3 is formed by plating such as Au.
[0022]
The conductive pattern 3 is also formed on the bottom surface (not shown) through the side surface of the substrate 1, and the conductive pattern formed on the bottom surface is an external connection terminal.
[0023]
The piezoelectric vibrating reed 5 has silver excitation electrodes 6 formed on the front and back surfaces.
[0024]
The lid 2 has a box shape, and an edge of the lid 2 is provided with a sealing material 4 such as an epoxy resin adhesive or low melting point glass.
[0025]
The conductive adhesive 7 is a thermosetting conductive adhesive mainly composed of epoxy, polyimide, silicone, etc., and a hygroscopic agent 8 such as synthetic zeolite (manufactured by Union Carbide), which is called silica or molecular sieve in advance. The mixture is mixed at a predetermined mixing ratio and applied to a part of the conductive pattern 3.
[0026]
Here, the mixing ratio of the conductive adhesive and the hygroscopic agent is a volume ratio, and the conductive adhesive is mixed at 1 with respect to the hygroscopic agent in the range of 0.3 to 1. When the proportion of the hygroscopic agent is less than 0.3 by volume, the hygroscopic effect is not different from the conventional one. In addition, when the ratio of the hygroscopic agent exceeds 1 in volume ratio, the viscosity increases, the problem that threading or the like occurs at the time of application and the mountability deteriorates, and the adhesive strength is significantly reduced, There also arises a problem that the impact resistance characteristics of the product are remarkably deteriorated.
[0027]
Then, the piezoelectric vibrating piece 5 is placed at a predetermined position so that a part of the excitation electrode 6 of the piezoelectric vibrating piece 5 is in contact with the conductive adhesive 7 containing a hygroscopic agent at a certain volume ratio. The conductive adhesive 7 is cured at a predetermined temperature. After curing, the piezoelectric vibrating reed 5 is fixed to the conductive pattern 3 and is electrically connected.
[0028]
The piezoelectric vibrating reed 5 which is secured to the conductive pattern 3, further depositing silver on the excitation electrode 6 is adjusted to a predetermined frequency, wherein the substrate 1 which is fixed to the piezoelectric vibrating reed 5, the lid 2 Sealing is performed by fusing the provided sealing material 4 at a predetermined temperature.
[0029]
Next, a second embodiment of the present invention will be described. FIG. 3 is a sectional view showing a second embodiment of the present invention.
[0030]
A first conductive adhesive 20 is applied to the conductive pattern 13 formed on the substrate 11, and the piezoelectric vibrating piece 15 is fixed to a predetermined portion so that the conductive adhesive 20 contacts a part of the piezoelectric vibrating piece 15. The second conductive adhesive 17 which is placed at the position and mixed with the hygroscopic agent 18 in advance is applied onto the first conductive adhesive 20 and a part of the piezoelectric vibrating piece 15, and a predetermined temperature is applied. Then, the conductive adhesives 17 and 20 are cured. Here, since the first conductive adhesive 20 does not contain a hygroscopic agent, the adhesion between the conductive pattern 13 and the first conductive adhesive 20 is further improved as compared with the first embodiment. As a piezoelectric vibrator, impact resistance can be improved.
[0031]
Thereafter, the piezoelectric vibrating piece 15 fixed to the conductive pattern 13 is adjusted to a predetermined frequency, and the substrate 11 to which the piezoelectric vibrating piece 15 is fixed fixes the sealing material 14 provided on the lid 12 to a predetermined value. Sealed by fusing at temperature.
[0032]
As described above, moisture that has entered the package is absorbed by the moisture absorbent mixed with the conductive adhesive, preventing the oxidation of the silver electrode of the piezoelectric vibrator piece, which is extremely oxidizable, and preventing the deterioration of the characteristics. .
[0033]
Further, since the hygroscopic agent is mixed with the conductive adhesive, it is not necessary to secure an area for newly applying the hygroscopic agent, and a package size equivalent to the conventional one can be achieved.
[0034]
In the first and second embodiments, the piezoelectric vibrator is fixed only with the conductive adhesive. However, as shown in FIG. 4, a non-photosensitive adhesive such as a reinforcing photo-curing adhesive mixed with a hygroscopic agent in advance is used. The conductive adhesive 29 can also be applied to a piezoelectric vibrator that is applied so that the piezoelectric vibrating piece 25 is fixed to the substrate 21 and is sealed by the substrate 21 and the lid 22.
[0035]
Next, FIG. 5 shows a cross section of a piezoelectric oscillator as an application example of the present invention.
[0036]
The substrate 31 is an insulator such as ceramic, and a seal ring 50 such as a Kovar material is provided on the outer peripheral portion. A conductive pattern 33 is formed on the substrate 31.
[0037]
The semiconductor element 40 is fixed to the conductive pattern 33 with a conductive adhesive 37 containing a hygroscopic agent 38, and is electrically connected to the conductive pattern 33 by a thin metal wire 42.
[0038]
The piezoelectric vibrating piece 35 is fixed to a part of the conductive pattern 33 electrically connected to the semiconductor element 40 with a conductive adhesive 37 containing a hygroscopic agent 38.
[0039]
The substrate 31 and the lid 32 are sealed by welding or the like.
[0040]
In the piezoelectric oscillator of one application example of the present invention, the piezoelectric vibrating piece is fixed to the substrate with a conductive adhesive containing a hygroscopic agent. However, the piezoelectric vibrating piece is fixed to the substrate with the configuration shown in FIGS. You may do it.
[0041]
【The invention's effect】
As described above, according to the present invention, the moisture absorbing agent absorbs moisture that has entered the package by mixing the moisture absorbing agent with the adhesive that fixes the piezoelectric vibrating piece. By preventing the formed silver electrode from being oxidized at a low cost but extremely easily oxidized , it is possible to realize a piezoelectric vibrator that is low in cost and has no deterioration in characteristics.
[0042]
Further, since the hygroscopic agent is mixed with the adhesive for fixing the piezoelectric vibrating piece, it is not necessary to secure a new application area for the mixture of the hygroscopic agent and the adhesive in the package. At the same time as the package size becomes possible, it is possible to prevent an increase in man-hours and costs.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of a piezoelectric vibrator of the present invention.
2 is a cross-sectional view showing details of a fixing portion of the piezoelectric vibrator of FIG. 1;
FIG. 3 is a cross-sectional view showing a second embodiment of the piezoelectric vibrator of the present invention.
FIG. 4 is a perspective view showing a third embodiment of the piezoelectric vibrator of the present invention.
FIG. 5 is a cross-sectional view showing an application example of the present invention.
FIG. 6 is a perspective view showing a conventional piezoelectric vibrator.
[Explanation of symbols]
1, 11, 21, 31 ... substrate 2, 12, 22, 32 ... lid 3, 13, 33 ... conductive pattern 4, 14 ... sealing material 5, 15, 25, 35 ... Piezoelectric vibrating piece 6 ... excitation electrodes 7, 17, 20, 37, 47 ... conductive adhesive 8, 18, 38, 48 ... hygroscopic agent 29 ... non-conductive adhesive 40 ... Semiconductor element 42 ... fine metal wire 50 ... sealing

Claims (2)

In a plate-like piezoelectric vibrator in which a piezoelectric vibrating piece having a silver electrode is sealed with a substrate and a lid, the thermosetting conductive adhesive and the hygroscopic agent are in a volume ratio of 1: 0.3 to 1. A piezoelectric vibrator, wherein the piezoelectric vibrating reed is electrically connected to a conductive pattern provided on the substrate with a mixed adhesive and is fixed to the substrate. In a plate-like piezoelectric vibrator that seals a piezoelectric vibrating piece having a silver electrode with a substrate and a lid, a first conductive adhesive that does not contain a hygroscopic agent is applied to the conductive pattern provided on the substrate and the piezoelectric A second conductive adhesive in contact with the vibrating piece and in which a thermosetting conductive adhesive and a hygroscopic agent are mixed at a volume ratio of 1 to 0.3 to 1 is used as the first conductive adhesive. And a piezoelectric vibrator in contact with the piezoelectric vibrating piece, electrically connecting the piezoelectric vibrating piece to a conductive pattern provided on the substrate and fixing the piezoelectric vibrating piece to the substrate.

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