JPH02123807A - Manufacture of crystal resonator - Google Patents

Abstract

PURPOSE:To obtain a crystal resonator in which the air-tightness of a sealing part is excellent by interposing a sheet made of a low softening point glass to a joining face between a case and a cover and softening the sheet so as to adhere the cover and the case. CONSTITUTION:At first, silver is vapor-deposited for exciting electrodes 2a, 2b to both front and rear sides of a crystal plate 1 and a conductive adhesives is used for them to fix them onto a support 7 of lead wires 3a, 3b. They are contained in the case 4, a glass sheet 6 is placed at the ridge of the case 4 and adhered tentatively by heating it to 420 deg.C. On the other hand, the glass sheet 6 is placed on the ridge surrounding the cover 5, and adhered tentatively by heating it to 420 deg.C. Then the case 4 and the cover 5 are opposed and provided in a vacuum heating furnace, which is evacuated to vacuum 10<-6>Torr to exhaust the air in the inside of the case 4 through the gap between the case 4 and the cover 5. Moreover, the case is heated up to 430 deg.C while keeping the vacuum to soften the glass sheet 6 and to make the sealing complete. Thus, the crystal resonator with high air-tightness is obtained.

Description

[Detailed description of the invention] Ru.

BACKGROUND OF THE INVENTION In recent years, crystal oscillators have been used in almost all electrical products such as VTR1 watches, communication devices, and telephones. FIG. 1 shows an exploded perspective view of a conventional crystal resonator, and FIG. 2 shows an exploded perspective view of the area around a crystal plate of the crystal resonator. Reference numeral 1 designates a crystal plate, which has excitation electrodes 2 al 2 b made of metal vapor deposited films on both its front and back surfaces, and lead wires 3 a + 3 b connected to these electrodes are fixed with a conductive adhesive. 4 is a box-shaped case for housing the crystal plate 1; 5 is a lid for sealing the opening; a sealing composition 6 has been applied in advance to the joint surface between the case and the lid.

Place the crystal plate 1 in the case 4, and connect the lead wires 3a and 3b to the second
As shown in the figure, cover with the lid 5 while pulling it out of the case.
The sealing composition is mixed with a softener and a binder in a vacuum heating furnace to form a paste.

Problems to be Solved by the Invention Crystal resonators constructed in the conventional manner often exhibit large fluctuations in frequency (∆F), and this tendency is particularly noticeable in high-frequency crystal resonators (e.g., 20 MHz,
(30MHz resonator), often with ∆F- of ±2
Sometimes it deviated from 0 ppm. The reason for this is not clear, but it is thought that volatile matter from the conductive adhesive or sealing composition adheres to the crystal plate, or stress is applied to the crystal plate.

Therefore, it is thought that the above problem can be solved if the vibration frequency can be adjusted after sealing. That is, one method is to use a transparent glass lid with a metal coating film on the inside as the lid, and after sealing, the metal coating film is evaporated with a laser through the lid to finely adjust the frequency. For this purpose, it is necessary to keep the inside of the case in a vacuum state of 10-' Torr or less, but conventionally, when sealing in a vacuum, a large number of air bubbles are generated in the sealing composition, resulting in the thickness of the sealed part being reduced. Often, the seal became thin and the seal was incomplete.

The bubbles are generated because the air contained in the glass powder and binder in the sealing composition comes out when the sealing composition is placed in a vacuum state.

In particular, conventional glass powders for sealing compositions have mainly been lead silicate glass, lead thallium borosilicate glass, or mixtures of these with ceramic powder; It has problems such as poor fluidity at the working temperature, which is the temperature at which it becomes easily fluid, making it difficult for air to escape, and thallium in the glass volatilizing and adhering to the crystal plate, increasing ΔF.

In view of the above problems, the present invention provides a method for manufacturing a crystal resonator with complete sealing and high airtightness.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention seals the case and the lid by softening a sheet made of low softening point glass interposed between their joint surfaces. .

Function: With the above-described structure, the present invention softens and seals the glass sheet that contains almost no air bubbles, making it possible to maintain a high vacuum inside the crystal resonator.
The frequency of the crystal resonator can be finely adjusted after sealing by a method such as evaporating a metal coat film inside the crystal resonator.

Examples Examples of the present invention will be described below. However, from 30
The average value of the thermal expansion coefficient at 250°C is hereinafter abbreviated as α.

Example 1 The structure of the crystal resonator constructed here is the same as that of the conventional example. However, lead wires 3a and 3b are made of 50 alloy (α: 95X
10-7/'C), forsterite (α = 100X 10-7/'C) was used for Case 4, and soda glass (α: 93XIO-7/'C) was used for the lid 5, respectively.

In addition, as the glass sheet 6, a glass powder GOI7-340 (coefficient of thermal expansion at 20 to 250°C: 70X 10-7/"C1 made by Sirot Nippon Co., Ltd. whose main components are lead monoxide and diboron trioxide) was used. In other words, the above glass powder was melted at 900°C in a platinum crucible, formed into a plate with a thickness of 0.2 mm, slowly cooled, and then processed using an ultrasonic processing machine (Japanese). Manufactured by Denshi Kogyo Co., Ltd.)
A rectangular frame-shaped glass sheet of the size of Case 4 was processed and used.

The method for manufacturing the crystal resonator of this example is as follows.

First, silver is vapor-deposited as excitation electrodes 2a and 2b on both the front and back surfaces of the crystal plate 1, and a lead wire 3 is attached to these using a conductive adhesive.
Fix it to the holding parts 7 of a and 3b. These are placed in a case 4, the glass sheet 6 is placed on the edge of the case 4, and 42
The lead wires 3 at 3 b are temporarily bonded by heating to 0°C. On the other hand, for the lid 5, a glass sheet 6 is placed on the surrounding edge, and
Temporarily bond by heating to 20°C. Next, the case 4 and the lid 5 are placed facing each other in a vacuum heating furnace, and the vacuum degree is 10-
By exhausting to 6 Torr, the air inside the case 4 is exhausted from the gap between the case 4 and the lid 5. Further, the glass sheet 6 is heated to 430° C. while being kept in a vacuum to soften the glass sheet 6 and complete the sealing. After the sealing was completed, the sealed portion was observed and no air bubbles were observed. In addition, we confirmed the airtightness of the crystal oscillator using a He leak test.
The amount of leakage was less than 5X 1G-1atm, cc/sec, and there was no leakage, and it was judged that the airtightness was sufficient.

Example 2 As the glass sheet 6, glass powder LS- manufactured by Nippon Electric Glass Co., Ltd. whose main components are lead monoxide and diboron trioxide was used.
0802 (α= 18×10-7/”C1 softening point 380
A crystal resonator was produced in the same manner as in Example 1 except for this. When the airtightness of the crystal resonator was confirmed by a He leak test, no leak was observed.

Example 3 426 alloy (α=80X 1
0-”/”C), alumina as case 4 (α=7
0X 10-'/'C), a different kind of soda glass from Example 1 was used as the lid 5 (α = 80X 10-7/'C).
), and as the glass sheet 6, a glass powder LS-2001B manufactured by Nippon Electric Glass Co., Ltd. whose main components are lead monoxide and diboron trioxide (α = 87.5
A crystal resonator was manufactured in the same manner as in Example 1 except for the above. When the airtightness of the crystal resonator was confirmed by a He leak test, no leakage was observed and the airtightness was confirmed. It was confirmed that the quality was sufficient.

Note that the same effect can be obtained by using silicate glass (α=$5X to-v/'C) instead of soda glass as the lid 5.

Example 4 Glass powder LS-0 manufactured by Nippon Electric Glass Co., Ltd. whose main components are lead monoxide and diboron dioxide was used as a glass sheet.
803 (α = 87.5X 1G-7/”C1 softening point 3
A crystal resonator was produced in the same manner as in Example 1 except for this. When the airtightness of the crystal resonator was confirmed by a He leak test, no leak was observed.

Comparative Example As in Example 1, a crystal plate 1 provided with a pair of excitation electrodes and lead wires is housed in a case 4. Next, on the edge of case 4,
A paste consisting of 100 parts by weight of glass powder LS-2001B, 1 part by weight of acrylic resin and 10 parts by weight of terpineol was applied and heated to 420°C to form a lead wire 3as.
Temporarily attach 3b. On the other hand, the same paste as described above is applied to the surrounding edge of the lid 5, and the lid is temporarily bonded by heating to 42θ°C. Next, the case 4 and the lid 5 are placed in a vacuum heating furnace, facing each other, and heated to a vacuum level of 10-' Torr. Thereafter, it is heated to 430°C to complete the sealing. After the sealing was completed, when the sealed portion was observed, many air bubbles were observed. Further, when the airtightness of the crystal resonator was confirmed by a He leak test, it was confirmed that leakage occurred and the airtightness was insufficient.

Effects of the Invention As described above, according to the present invention, a crystal resonator with excellent airtightness of the sealed portion can be obtained. Therefore, after sealing in vacuum, it is possible to finely adjust the frequency of the crystal resonator after sealing by evaporating a metal coating film provided inside in advance.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a crystal resonator used in an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the quartz plate and its surroundings. l...Crystal plate, 2a+2b...Excitation electrode, 3a
l 3 b...Lead wire, 4...Case, 5...
... Lid, 6... φ glass sheet, 7... Holding part. Name of agent: Patent attorney Shigetaka Kurino Haka 1 person r--Issui Buki 2α--1 Rita 4-M-Res 7-11 Mizusho board 2a--Issuke obscene shoulder flash Direct) e6 --- H3: Eye shoulder electric laura (!K) 3α-m-su-do tan 3 (, --- Lee F' 諌 7 --- Hoj # part

Claims (2)

[Claims] (1) A crystal plate equipped with a pair of excitation electrodes and lead wires connected to each electrode is placed in a case, a sheet made of low softening point glass is interposed on the joint surface between the case and the lid, and the sheet is softened. A method for manufacturing a crystal resonator, characterized in that the lid and the case are joined together. (2) The method for manufacturing a crystal resonator according to claim 1, wherein the low softening point glass constituting the glass sheet contains at least lead monoxide and diboron trioxide, and has a softening point of 380° C. or lower. .