JPH09260990A - Press-fit sealed type crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a production process by providing satisfactory air-tightness due to press-fitting without using plating processing or the like by smoothly finishing the inner surface of a sealed tube through chemical treatment. SOLUTION: A crystal oscillator 4 is assembled from two leads 5 and held on an air-tight terminal 2. Concerning the outer peripheral face of the air-tight terminal 2, copper plating is performed onto the base, and solder plating 3 of soft plating is performed onto it. A sealed tube 1 is composed of the deep drawing press working mold of any one of 42Ni, german silver, stainless, aluminum and kover and the crystal oscillator is sealed air-tightly by press-fitting the sealed tube 1 into the planting part 3 of the assembled air-tight terminal 2. In this case, before the press-worked sealed tube 1 is press-fitted, it is immersed in the mixed acid solution of 19% nitric acid, 40% sulfric acid, 1% hydrochloric acid and 40% water for about one minute so that it can be finished into smooth plane by chemically treating the flaw, etc., having the depth of about 3μm generated on the inner face by press-working. Even without performing the plating processing onto the sealed tube 1, no leakage is generated by press-fitting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press-fit sealed quartz oscillator.

[0002]

2. Description of the Related Art A sealed tube used for a crystal unit is formed by press working (deep drawing), and the material of the sealed tube is 42Ni of nickel and 42Ni of iron and nickel white. Etc. are used.

The sealing tube formed by press working is solder-plated or Ni-plated on its inner surface in order to enhance airtightness with the airtight terminal. For example, copper plating is applied to the base to a thickness of 2 μm to 5 μm, and then solder plating is applied to 1
A sealed tube having a thickness of 0 μm is used.

The sealing tube having the inner surface plated is solder-plated on the outer peripheral surface, and is press-fitted and sealed in an airtight terminal in which a crystal vibrating piece is assembled to form a crystal resonator. Applying solder plating or Ni plating to the sealing tube is
This is to prevent the occurrence of leakage during press fitting. In addition, plating is applied to prevent the material from corroding and to prevent the material from discoloring due to oxidation or the like.

[0005]

The sealing tube formed by press working (deep drawing) is
Countless scratches will be formed on the inner surface of the sealed tube. Many of the scratches are vertical scratches in the pressing direction, and the scratches have a width of 1 μm, a length of several mm, and a depth of 2 to 3 μm.

If the inner surface of the sealing tube is plated with the above-mentioned scratches left, the scratches will be covered by the plating, and the gas or plating solution will be trapped in the recesses of the scratches. If the sealed tube is press-fitted into the airtight terminal in such a state, the confined gas will leak into the sealed tube after the completion of the crystal unit, which will greatly affect the oscillator characteristics such as the deterioration of the CI value. Become. In addition, the plating liquid and the like are gasified and diffused into the sealed tube, which adversely affects the characteristics of the crystal unit.

Further, when the sealing tube is subjected to a plating treatment such as solder plating or Ni plating, the plating film may occlude gas generated during plating, impurities in the plating solution, organic substances and the like. After the oscillator is completed, the occluded gas or the like is generated as a gas from the inside of the film and adversely affects the CI value increase, frequency shift, and the like, and deteriorates the characteristics of the oscillator.

[0008] Therefore, the present invention is to provide a press-fit sealed quartz oscillator in which scratches and irregularities formed by press working are finished into a smooth surface, and deterioration of oscillator characteristics due to gas generation is prevented. .

[0009]

In order to solve the above problems, the present invention has the following constitution. The sealed tube formed by pressing is immersed in a mixed acid solution of nitric acid, sulfuric acid, hydrochloric acid, and water for chemical treatment. The sealed tube that has been subjected to the chemical treatment is press-fitted and sealed in an airtight terminal in which a crystal vibrating piece is assembled to form a crystal resonator.

The sealing tube is simply immersed in a mixed acid solution of nitric acid, sulfuric acid, hydrochloric acid and water for chemical treatment, and is not subjected to plating treatment, and is press-fitted and sealed in an airtight terminal as it is. .

[0011]

FIG. 1 is a cross-sectional view of a press-fit sealed quartz oscillator showing an embodiment of the present invention. The sealing tube 1 is formed by pressing (deep drawing), and the material is nickel silver. The sealing tube is immersed in a mixed acid solution of nitric acid, sulfuric acid, hydrochloric acid and water for chemical treatment before being press-fitted and sealed in the hermetic terminal 2. When the sealed tube is formed by press working, the inner surface of the sealed tube is damaged innumerably.
The scratches and irregularities formed at this time can be finished into a smooth surface by the chemical treatment.

The mixed acid solution contains 19% nitric acid and 4% sulfuric acid.
A mixture of 0%, 1% hydrochloric acid, and 40% water is used as a guide, and is immersed in this mixed acid solution for about 1 minute for chemical treatment. Further, the nickel silver used for the sealed tube has a problem of discoloration due to corrosion or oxidation, but discoloration can be prevented by immersing it in the mixed acid solution.
It should be noted that, if the measure for preventing discoloration is surely taken, solder plating may be applied to the outer peripheral surface of the sealing tube after the crystal unit is completed.

Reference numeral 2 shown in FIG. 1 is an airtight terminal. A plating portion 3 is applied to the outer peripheral surface of the airtight terminal 2. Reference numeral 4 is a crystal vibrating piece, which is assembled to the lead 5 of the airtight terminal 2. Although only one lead is shown in FIG. 1, another lead is actually provided on the back surface side of the crystal vibrating piece 4, and the crystal vibrating piece is sandwiched between two leads and fixed. In order to increase the airtightness of the plated portion 3 with the sealing tube, the base is copper-plated and the soft-plated solder is plated on the base. The sealed tube 1 that has been subjected to the chemical treatment described above,
The crystal resonator is formed by press-fitting and sealing the airtight terminal 2 in which the crystal vibrating piece 4 is assembled.

Table 1, Table 2, FIG. 2 and FIG. 3 show the results of evaluating the characteristics of the conventional crystal unit and the crystal unit according to the present invention. A tuning fork type crystal unit was used for each of the conventional crystal unit and the crystal unit according to the present invention. Table 1 is a table showing the heat resistance test results of the conventional crystal unit and the crystal unit of the present invention. FIG. 2 is a graph showing changes in frequency in a heat resistance test of the conventional crystal unit and the crystal unit of the present invention. FIG. 3 is a graph showing changes in CI value in a heat resistance test of the conventional crystal unit and the crystal unit of the present invention. The set temperature for the heat resistance test is 85 ° C. The frequency change of the conventional crystal oscillator is −3 ppm in 240 hours and −8 ppm in 1000 hours, and the change to the negative side becomes large with the passage of time. On the other hand, the frequency change of the crystal unit according to the present invention was 0.6 ppm in 240 hours and 2.5 ppm in 1000 hours. In the case of the crystal resonator according to the present invention, the frequency does not change significantly and the characteristics are good. The change in CI value in the heat resistance test is 6 kΩ in 240 hours and 1 in 1000 hours in the case of the conventional crystal unit.
In contrast to the change of 0 kΩ, in the case of the crystal resonator according to the present invention, the change is about 0.5 kΩ in 240 hours and about 1 kΩ in 1000 hours, and the characteristics of the vibrator are significantly improved without significant variation. Generally, the frequency change and the CI value change of the crystal unit are correlated with the degree of vacuum inside the crystal unit and the addition of mass to the crystal vibrating piece. Decreases and the CI value increases. According to the present invention, it is possible to suppress the occurrence of problems such as deterioration of vacuum degree and addition of mass based on the test results. As a result of examining the amount of gas generated in the sealed tube after completion of the crystal unit, the conventional crystal unit generates 0.0001 ml / atm, whereas the crystal unit of the present invention has 0.000005 ml / atm.
The generated amount is ml / atm, which is a very small amount.

[0015]

[Table 1]

Table 2 shows data of aging characteristics. Aging was performed for 30 days and the characteristics of the conventional crystal unit and the crystal unit according to the present invention were evaluated. As a result, in the case of the conventional crystal unit, the frequency changes by 0.7 ppm. In the child, the frequency changed by about 0.1 ppm.

[0017]

[Table 2]

As described above, as a result of the heat resistance test and the evaluation of the aging characteristics, the crystal unit according to the present invention is
By chemically treating the sealing tube, it can be finished to a smooth surface and can be press-fitted and sealed without plating, so problems such as gas generation can be reduced, and compared to conventional crystal oscillators, oscillators The characteristics can be greatly improved.

Although the evaluation of the characteristics described above is the result of the tuning fork type crystal unit, the characteristics of the unit can be similarly improved even in the case of a rectangular crystal unit. Further, in the embodiment of the present invention, nickel-white is used as the material of the sealing tube, but other materials, for example, 42Ni, stainless steel, aluminum, Kovar, etc. may be used. By performing the above, a good crystal unit can be obtained.

[0020]

EFFECTS OF THE INVENTION Since the surface finish of the sealing tube can be made smooth, the occurrence of leakage due to press-fitting can be eliminated without performing plating treatment. Therefore, problems such as deterioration of CI value due to gas generation are eliminated, and the characteristics of the vibrator are significantly improved. Further, since it is not necessary to plate the sealing tube, the manufacturing process can be simplified and a great effect can be achieved in terms of cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a press-fitted and sealed crystal resonator according to an embodiment of the present invention.

FIG. 2 is a graph showing changes in frequency in a heat resistance test of a conventional crystal unit and a crystal unit of the present invention.

FIG. 3 is a graph showing changes in CI value in a heat resistance test of a conventional crystal unit and a crystal unit of the present invention.

[Explanation of symbols]

 1 sealed tube 2 airtight terminal 3 plated part 4 crystal vibrating piece 5 lead

Claims (3)

[Claims] 1. A press-fit sealed crystal resonator in which a sealed tube is press-fitted and sealed in an airtight terminal in which a crystal vibrating piece is assembled, and the sealed tube is chemically treated to form a sealed tube. Is a press-fitted and sealed crystal resonator, which is press-fitted and sealed with the airtight terminal without performing plating treatment. 2. The press-fit sealed quartz oscillator according to claim 1, wherein the chemical treatment is performed by immersing the sealed tube in a mixed acid solution of nitric acid, sulfuric acid, hydrochloric acid and water. 3. The press-fit sealed quartz oscillator according to claim 1, wherein the sealing tube is made of any one of 42Ni, nickel silver, stainless steel, aluminum and Kovar.