JP2001111379A - Manufacturing method of sealing tube for crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make satisfactory the soldering of a sealing tube plated with nickel on the surface for a crystal oscillator. SOLUTION: A crystal oscillator sealing tube plated with nickel on the surface is heat-treated by setting an in-furnace pressure at 6.65 Pa or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sealing tube for a quartz crystal resonator, the surface of which is plated with nickel.

[0002]

2. Description of the Related Art In order to enable soldering in a reflow furnace or the like, a surface mount type crystal unit having improved heat resistance has been put to practical use. FIG. 1 is an exploded perspective view of a crystal unit according to the present invention. 1 is a sealing tube, 2 is an airtight terminal, 3 is a lead, 4 is a crystal piece, and 5 is an electrode formed on the crystal piece. The crystal resonator is completed by fixing the crystal blank 4 to the inner lead 3a of the lead 3 embedded in the airtight terminal 2 and press-fitting the airtight terminal 2 to which the crystal blank 4 is fixed into the sealing tube 1. It is a cylinder type crystal oscillator.

FIG. 2 is a side view of a cylinder type crystal unit which is compatible with surface mounting. The cylinder type crystal resonator completed as described above is formed as shown in FIG. 2 by bending the lead 3 into a predetermined shape and corresponding to surface mounting. In surface mounting, a quartz oscillator is mounted on a circuit board using a mounter which is an automatic machine like other electronic components, and is soldered in a reflow furnace. At this time, it is soldered directly to the circuit pattern to ground the sealing tube.

[0004] In a reflow furnace, the crystal oscillator is 240-2.
Since the crystal unit is exposed to a high temperature atmosphere of 60 ° C., the heat resistance of the crystal unit must be improved. FIG. 3 is a sectional view of the hermetic terminal. The hermetic terminal 2 has an outer peripheral metal part 6, glass 7,
Although the lead 3 and the outer peripheral metal portion 6 are formed by plating 8, the lead 3 may be exposed in the high-temperature atmosphere.
The plating 8 uses a high-temperature solder (for example, lead: remainder = 9: 1). High-temperature solder plating is applied to the leads 3 at the same time as the outer peripheral metal portion 6. However, since high-temperature solder plating has poor solderability during reflow, eutectic solder plating may be further applied. On the other hand, in order to obtain heat resistance of the sealing tube,
Generally, the material surface is plated with nickel.

[0005]

The sealing tube is subjected to a vacuum heat treatment before sealing, but the nickel-plated sealing tube is formed with a surface film (an oxide film or the like) before performing the vacuum heat treatment. Depending on the conditions of the vacuum heat treatment, the formation of a surface film is promoted. The formation of the surface coating deteriorates the solderability.

[0006] If the soldering becomes defective, the grounding of the sealing tube cannot be taken, and the oscillation frequency may become unstable.

[0007]

Means for Solving the Problems A sealed tube for a crystal unit, whose surface is nickel-plated, is heat-treated at a pressure (vacuum) of 6.65 Pa or less in a vacuum heat treatment furnace.

[0008]

FIG. 4 is a sectional view of a sealing tube according to the present invention. Nickel plating 10 is applied to the surface of the sealing tube 9, and a coating 11 is gradually formed on the surface of the nickel plating 10. In the method of manufacturing a sealed tube for a crystal resonator according to the present invention, the heat treatment of the sealed tube 9 is performed by setting the pressure in the vacuum heat treatment to 6.65 Pa or less. Other conditions of the vacuum heat treatment were a heat treatment temperature of 200 ° C. and a heat treatment time of 72 hours.

FIG. 5 is a graph showing the pressure in the vacuum heat treatment furnace and the rate of occurrence of defective soldering. Vacuum heat treatment of the sealing tube was performed at a pressure in the vacuum heat treatment furnace of 1.33 to 66500 Pa, and after mounting the circuit board, soldering was confirmed in a reflow furnace. As shown in the graph, it can be seen that there is a correlation between the pressure in the vacuum heat treatment furnace and the incidence of defective soldering. And it turned out that a soldering failure does not generate | occur | produce when heat processing is carried out by setting the pressure in a vacuum heat treatment to 6.65 Pa or less.

[0010]

According to the manufacturing method of the present invention, occurrence of defective soldering can be suppressed even in a sealing tube whose surface is nickel-plated in order to enhance heat resistance.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a crystal resonator according to the present invention.

FIG. 2 is a side view of a cylinder-type crystal unit compatible with surface mounting.

FIG. 3 is a sectional view of an airtight terminal.

FIG. 4 is a sectional view of a sealing tube according to the present invention.

FIG. 5 is a graph showing the pressure inside the vacuum heat treatment furnace and the incidence of soldering defects.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing tube 2 Airtight terminal 3 Lead 3a Inner lead 4 Crystal piece 5 Electrode 6 Outer peripheral metal part 7 Glass 8 Plating part 9 Sealing tube 10 Nickel plating part 11 Surface coating

Claims (1)

[Claims] 1. A method for manufacturing a sealed tube for a quartz oscillator, wherein the sealed tube for a quartz oscillator having a nickel plated surface is heat-treated at a furnace pressure of 6.65 Pa or less. .