JPH10335963A - Crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb moisture and gas molecules, to reduce frequency difference before and after sealing and to improve yield by enclosing and arranging an absorbing material which mixes absorbing particles with a soft host resin which is less than specific rigidity in an enclosed container. SOLUTION: This surface mounting oscillator has an excitation electrode that consists of silver electrode and leader electrode 1 in a resin-sealed container which consists of a base 3 and a cover 4 which are both made of ceramics, and a crystal piece 2 whose both ends are held by the base 3 with conductive adhesive 8 is enclosed. A recessed part 9 is provided in the base 3, and an absorbing material 10 which mixes absorbing particles 12 with silicone resin 11, whose rigidity is less than HB in the case of pencil rigidity with a prescribed allocation ratio is filled. With this, mesh of silicone resin is made large, and permeability is made good. Grains such as moisture and organic solvent are passed through, the particles 12 absorb sufficiently, moisture, etc., is prevented from attaching to the oscillator, and the change in frequencies before and after sealing is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal resonator, and more particularly to a surface mount type crystal resonator (hereinafter referred to as a surface mount resonator) having a reduced frequency difference between before and after sealing a sealed container.

[0002]

[Prior art]

(Background of the Invention) Quartz resonators are often used in various devices as frequency and time reference sources or filter elements because of their excellent resonance characteristics. In recent years, the standards for each characteristic are strict. For example, there is a demand for a surface mount resonator for AV having a frequency deviation at room temperature within ± 10 ppm.

FIG. 3 is a diagram of a surface-mount vibrator for explaining a conventional example. The surface mount vibrator has a crystal blank 2 sealed in a sealed container 1. The hermetically sealed container 1 includes a flat base 3 made of ceramic and a concave cover 4. After enclosing the crystal blank 2, the base 3 and the cover 4 are coated with the bonding resin 5 applied to the outer periphery of the cover 4 for about 150 minutes.
Heated and melted at ℃ and sealed. The joining resin 5 is made of, for example, an epoxy resin.

[0004] The crystal blank 2 is, for example, an AT cut, and as shown in Fig. 2, a lead electrode 7 (ab) extends from the excitation electrode 6 (ab) on both main surfaces to both ends. The excitation electrode 6 and the extraction electrode 7 are, for example, silver electrodes formed by vapor deposition. Then, the crystal blank 2 is opposed to the surface of the base 3, and both ends are fixed and held by the conductive adhesive 8.

[0005]

[Problem to be Solved by the Invention]

(Problems of the prior art) However, in the surface mount resonator having the above configuration, there was a phenomenon in which the vibration frequency changes before and after the sealing of the crystal blank 2, that is, before and after the sealing of the base 3 and the cover 4. That is, when the base 3 and the cover 4 are sealed by heating and melting the joining resin 5, fine particles such as water and an organic solvent from the joining resin 5 scatter and adhere to the excitation electrode 6 (ab). There was a phenomenon that the vibration frequency decreased due to the mass load effect. In particular, in the case of a silver electrode, fine particles were easily taken in as compared with a gold electrode or the like, and the tendency was strong.

[0006] For this reason, the surface mount resonator has been sealed beforehand by setting the vibration frequency to a higher value. There is a problem that it is difficult to keep the frequency deviation within the frequency deviation, that is, the yield is poor. Although it was considered that the silver electrode was replaced by a gold electrode, gold was expensive.
Especially in the case of mass production, it causes an economic problem.

(Object of the Invention) It is an object of the present invention to provide a crystal resonator having an improved yield by reducing a frequency difference before and after sealing.

[0008]

Means to be Solved by the Invention

(Points of interest in the invention)
Attention was paid to the technology of the publication. That is, attention was paid to the point that moisture and gas molecules entering the container were adsorbed by the desiccant and the characteristics were stably maintained. The hygroscopic agent uses a base resin as an epoxy resin and adsorbed particles (synthetic zeolite) mixed therein.

(Solution Means) The present invention is basically based on the fact that a matrix resin is made of a soft silicone resin having a pencil hardness of HB or less, and an adsorbent in which adsorbed particles are mixed is disposed in a closed container. It is an important solution.

[0010]

According to the present invention, since the matrix resin is a silicone resin having a pencil hardness of HB or less, the gap between each net of the net structure, which is the molecular structure of the silicone resin, is increased, and the permeability is increased. improves. Therefore, fine particles such as moisture and organic solvents can easily pass through, and thus have the effect of being sufficiently taken in by the adsorbed particles in the silicone resin. Less than,
An embodiment of the present invention will be described.

[0011]

FIG. 1 is a view of a surface-mount vibrator for explaining an embodiment of the present invention. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified. As described above, the surface-mounting vibrator includes an excitation electrode 6 (ab) composed of a silver electrode and an extraction electrode 7 (ab) in a hermetically sealed container 1 composed of a base 3 and a cover 4, both of which are made of ceramic. The quartz pieces 2 whose both ends are held on the base 3 by the conductive adhesive 8 are sealed.

In this embodiment, a depression 9 is provided in the base 3 and an adsorbent 10 is filled. The adsorbent 10 is formed by mixing adsorbed particles 12 with a silicone resin 11 as a base resin. Both (silicone resin 11 and adsorbed particles 1
Here, the blending ratio (weight ratio) of 2) is 4: 6. The hardness of the silicone resin 11 is 6B in pencil hardness. The reason why the adsorbent particles 12 are mixed with the base resin to form the adsorbent 10 is that the adsorbent particles 12 themselves have no adhesive action.

Table 1 below shows the case of the conventional example without the adsorbent 10 (A), the case where the base resin of the adsorbent 10 of the present invention is an epoxy resin (B), and the adsorbent 10 according to the present embodiment. When the base resin of (C) is a silicone resin,
It is an experimental result showing a frequency deviation Δf / f (ppm) before and after sealing. Note that f is the nominal frequency of the vibrator, Δf is the frequency difference between the vibrating frequencies f ₁ and f ₂ before and after sealing (f ₂ −f _01. The nominal frequency in this example is 32 MHz, and the number of samples is respectively There are 30.

Δf / f ABC Average value (ppm) −27.3 −15.0 2.8 Maximum value (same) −22.9 −10.3 5.1 Minimum value (same) −33.7 -17.4 -1.2

As is apparent from these tables, in the case of the present embodiment (C), the average value is about 1/10 or less of that of the conventional example without the adsorbent 10 (A). When the resin is an epoxy resin, the frequency deviation becomes 1/5 or less with respect to (B). The variation between the maximum value and the minimum value is about 11 ppm in the case of the conventional example (A), 7 ppm in the case of the epoxy resin (B), and 6 p in the case of the present example (C).
pm.

In the case of the present embodiment (C), the vibration frequency after sealing changes in the positive direction. This is because the frequency fluctuation factor in the negative direction due to the contraction of the conductive adhesive due to the above is superior. In contrast, the conventional example (A)
In the case of the epoxy resin (B), the vibration frequency changes in the negative direction because the frequency rise factor due to the load mass is superior to the frequency rise factor.

The following conclusions were obtained by considering the above experiment. That is, in the case of the conventional example (A), as described above, the fine particles scattered from the bonding resin 5 at the time of sealing adhere to the excitation electrode 6 (ab) and the frequency after sealing is reduced by the load mass effect. It drops significantly. Further, when the adsorbent 10 is used (BC), the fine particles are taken in by the adsorbed particles 12 and the adhesion to the excitation electrode 6 (ab) is reduced. Therefore, the frequency deviation before and after sealing is reduced as compared with the conventional example.

A comparison of a case where the base resin containing the adsorbed particles 12 is an epoxy resin and a silicone resin is presumed as follows. That is, in the case of an epoxy resin, the molecular structure of the net structure is dense, and the permeability of fine particles is poor. Therefore, as shown schematically in FIG. 2 (a), the fine particles 13 are merely taken into the adsorbed particles 12 on the vicinity of the surface of the adsorbent 10, thereby lowering the adsorption efficiency.

On the other hand, in the case of the silicone resin 11, the molecular structure of the net structure is generally sparse. That is, the gap between the nets is large. Therefore, the permeability of the fine particles is improved. The more flexible the molecular structure becomes.
For this reason, the fine particles 13 penetrate deep into the inside and are taken into the adsorbed particles 12 evenly.
FIG. 2 (b) indicates that the adsorption efficiency can be increased.

As described above, with the configuration using the adsorbent 10 in which the resin matrix is a flexible silicone resin, the frequency deviation before and after sealing can be reduced as described above. Therefore, since the expected frequency before sealing is small, the adjustment operation is facilitated, and the error before and after sealing is reduced. From this, especially in the case of mass production, almost all the products can be set within the standard as non-defective products, and the yield can be improved. Further, the variation is small and the yield is further improved.

In this embodiment, the base 3 has a recess 9.
Is provided and the adsorbent 10 is filled, so that the height dimension of the surface-mount vibrator can be kept small. In addition, even if the recess 9 is provided,
Since the thickness of the outer periphery is the same, the strength of the base 3 itself is maintained.

[0022]

[Other Matters] In the above embodiment, the mixing ratio of the silicone resin 11 and the adsorbed particles 12 was set to 4: 6. However, the silicone resin 11 only has to have an adhesive action, and about 3: 7 is sufficient.

The pencil hardness of the silicone resin 11 is 6
B was used, but its hardness was generally lower than that of epoxy resin (about 3 to 9H). In the present invention, the pencil hardness of the silicone resin 11 is specified to be HB or less, but this is a hardness of a molecular structure generally called soft, and if a soft resin is used, the same effect as that of the embodiment can be expected. It is specified as a guide. Note that, regardless of the pure silicone resin 11, a silicone resin having a pencil hardness of HB or less may be used.

[0024] Also, the silicone resin is defined as a silicone resin.
For example, even if the epoxy resin is modified to have a hardness of about HB, in this case, heat resistance is lacking and is not suitable for practical use.

Further, a depression 9 is provided in the base 3 so that the adsorbent 1
Although 0 is filled, it may be fixed on the flat base 3 without providing the depression 9. In addition, the description has been given by applying the present invention to the surface mount resonator. However, the present invention is not limited to this.

The present invention can be appropriately modified without departing from the spirit of the present invention. In short, an adsorbent 10 having a silicone resin having a pencil hardness of HB or less as a base resin is disposed in the closed container 1. The one that prevents the frequency change before and after sealing belongs to the technical scope of the present invention. It is needless to say that the aging (time-dependent change) characteristics can be improved by adsorbing fine particles such as moisture entering the closed container 1 after the sealing.

[0027]

According to the present invention, the adsorbent is formed by mixing adsorbent particles in a silicone resin having a pencil hardness of less than HB or less, and the adsorbent is disposed in a closed container. As a result, it is possible to provide a crystal resonator having an improved yield.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a surface-mount vibrator for explaining an embodiment of the present invention.

FIG. 2 is a schematic diagram of an adsorbent for explaining the operation of one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a surface-mount vibrator for explaining a conventional example.

FIG. 4 is a view of a crystal piece for explaining a conventional example.

[Explanation of symbols]

1 Closed container, 2 crystal pieces, 3 bases, 4 covers, 5
Bonding resin, 6 excitation electrode, 7 extraction electrode, 8 conductive adhesive, 9 depression, 10 adsorbent, 11 silicone resin, 12 adsorbed particles, 13 fine particles.

Claims (2)

[Claims] 1. A quartz oscillator in which an adsorbent in which adsorbed particles are mixed with a matrix resin is disposed in a closed container, wherein the matrix resin is made of silicone and has a pencil hardness of HB or less. Crystal oscillator. 2. The airtight container according to claim 1, wherein the closed container comprises a flat base and a concave cover, and a depression is provided on a surface of the base, and the depression is filled with the adsorbent. Crystal oscillator.