JPH0964680A - Quartz oscillator and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the dispersion of frequency and a defect rate by sealing the aperture end part of a seal tube applied to metallic outer ring and then eliminating the application of stress to a quartz oscillator chip or applying tensile stress to the chip. SOLUTION: Since the lower face of the metallic outer ring 6 is plane but the seal tube 5 is projected, tensile stress is applied to the quartz oscillator chip 1 sealed by the tube 5. When the chip 1 is sealed by the outer ring 6, tensile stress is applied to the sealed chip 1 in the shown arrow direction. This is caused by straightening the concave curve of the ring 6 and the lower face of a flange part 7 formed on the outer periphery of the ring 6 in the longitudinal direction of the chip 1 by the sealing and shaping two leads 3 like a V shape. Since the elimination of application of stress to the chip 1 may not be feasible, tensile force is applied to the chip 1 and adhesives are plastically deformed by heat treatment after sealing the chip 1 to ease the stress.

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 a method for manufacturing the same.

[0002]

2. Description of the Related Art As a structure of a crystal resonator, there is a crystal resonator having a structure in which a rectangular crystal vibrating piece as shown in a sectional view in FIG. The crystal vibrating piece 1 is supported by the tip portions 3 ′, 3 ′ of the pair of leads 3 and 3 that are insulated and sealed by penetrating the metal outer ring 2 and project from the upper surface of the metal outer ring.
The metal outer ring 2 is provided on the flange portion 4 that is integrally provided on the outer periphery of the
This is a structure for sealing the open end portion (flange portion 6) of the sealing tube 5 covering the upper portion.

5 and 6 are cross-sectional views for explaining changes in the shape of the flange portion before and after sealing. A small projection 4 ′ called a projection for welding the sealing tube 5 is formed on the upper surface of the flange portion 4, and the flange portion 4 of the metal outer ring 2 and the sealing tube 4 ′ are formed through the small projection 4 ′. The flange portion 6 of 5 is welded. The shape of both flanges is approximately oval when viewed from the top (HC49U / S is 1 in the longitudinal direction.
1.5mm), pressing the welding electrode matched to the flange shape from the top and bottom, and if current is applied under pressure, current concentrates on the projection part (small projection 4 ') and both flange parts are applied. Welded and sealed. As can be seen from FIG. 6, the flesh of the flange portion is crushed by the sealing and is pushed inward (in the arrow direction). FIG. 11 is a cross-sectional view of the crystal unit after sealing. Since the meat of the flange portion is brought close by the sealing, the two leads are formed in a V shape, and a compressive stress in the arrow direction is applied to the crystal vibrating piece 1.

FIG. 7 is an external view when the metal outer ring is processed to have a convex shape, and FIG. 8 is an external view when the outer peripheral surface of the flange of the metal outer ring has a burr. FIG. 9 is a view showing the state of leads when sealing is performed using such a metal outer ring, and is an external view. Even when the outer metal ring of FIGS. 7 and 8 is sealed, the two leads are in a V shape, and compressive stress is applied to the crystal vibrating piece.

[0005]

When the flange portion is welded (sealed), a compressive stress is applied to the crystal vibrating piece 1 and the crystal vibrating piece 1 bends, so that the frequency of the crystal vibrating piece changes.
The thickness T of the crystal vibrating piece varies depending on the oscillation frequency F, but becomes thinner as the frequency increases (expressed as FT = 1670). The thinner the quartz crystal vibrating piece 1, the more easily it is deformed by the compressive stress, and the change in the frequency becomes large due to the stress due to the deformation (it becomes remarkable when the frequency becomes 15 MHz or more). Since there is no directionality in the change of the frequency and there is a case where the frequency becomes high and a case where the frequency becomes low, it is not possible to adjust the frequency in consideration of the change amount before the sealing. Since the crystal vibrating piece does not easily oscillate when stress is applied to the crystal vibrating piece, the oscillation becomes unstable. If you try to drive the crystal unit at a low drive level, it may not oscillate. Although the main vibration is suppressed by the compressive stress (the series resonance resistance is deteriorated), spurious may be oscillated because there is a mode in which spurious is not suppressed. There is a great risk that spurious will couple to the main vibration due to external stress such as temperature shock. Since such a phenomenon is not taken into consideration when designing the dimensions of the quartz crystal resonator element, it is obvious that a problem occurs in performance, reliability and the like.

FIG. 10 is a graph showing the distribution of stress applied to the crystal vibrating piece after sealing, with the horizontal axis representing stress and the vertical axis representing frequency. The dotted line is according to the prior art and the solid line is according to the present invention. The shaded area in the figure is the defective portion, and the defective rate is 2-3%.

[0007]

Means for Solving the Problems A pair of leads, which penetrate through a metal outer ring and are insulated and sealed, support a quartz crystal vibrating piece at the tips of the leads projecting from the upper surface of the metal outer ring, and are integrated with the outer periphery of the metal outer ring. In the crystal unit for sealing the opening end of the sealing tube covered on the metal outer ring on the flange portion protruding from the structure, the vibrating piece is not stressed or has a tensile stress after the sealing. To do. For example, the lower surface of the metal outer ring is curved in a concave shape in the longitudinal direction of the crystal vibrating piece. In addition, a pair of leads, which penetrate through the metal outer ring and are insulated and sealed, support the crystal vibrating piece at the tips of the leads protruding from the upper surface of the metal outer ring, and are integrally formed on the outer periphery of the metal outer ring. On the top, when sealing the crystal unit that seals the open end of the sealing tube covered on the metal outer ring,
A manufacturing method is adopted in which a sealing die that is in contact with the lower surface of the metal outer ring is sealed with a convexly curved sealing die.

[0008]

2 and 3 are sectional views of a crystal unit for explaining the present invention (HC49U / S type, and the length of the crystal unit is about 8 mm). The metal outer ring 6 and the lower surface of the flange portion 7 provided on the outer periphery of the metal outer ring 6 are curved in a concave shape in the longitudinal direction of the crystal vibrating piece 1 (the direction of the arrow in the figure). 8
Is a jig for receiving the central portion of the lower surface of the metal outer ring used for sealing (welding), and 9 is a lower electrode for welding (sealing type). As shown in the figure, the flange outer circumference is 10
Warped up to -50 μm.

When sealing is performed using the metal outer ring as described above, tensile stress is applied to the crystal vibrating piece after sealing in the direction of the arrow shown in FIG. This is because the metal outer ring 6 and the lower surface of the flange portion 7 provided on the outer periphery of the metal outer ring 6 are curved in a concave shape in the longitudinal direction of the crystal vibrating piece 1 (the direction of the arrow in the figure). This is because the two leads have an inverted V-shape when the curvature is corrected and becomes flat.

FIG. 4 is a sectional view for explaining a sealing mold for carrying out the present invention. Although the lower surface of the metal outer ring is flat, the sealing mold (lower electrode for welding) 10 is formed in a convex shape. When sealing is performed using a sealing mold as shown in the figure, the quartz crystal resonator element after sealing is subjected to tensile stress as shown in FIG. This is because the metal outer ring is deformed into a convex shape following the shape of the sealing type by the sealing, and the two leads have an inverted C-shape.

The distribution of stress applied to the crystal resonator element after sealing the crystal resonator according to the present invention is shown by the solid line in FIG. 10, but almost no compressive stress is applied and tensile stress is applied. ing. Due to variations in parts, some compressive stress is applied, but this is not a problem for practical use. If possible, it would be good if the quartz resonator element was not stressed, but it is actually impossible. However, if the stress applied to the crystal vibrating piece is tensile stress,
After sealing, heat treatment (100-150 ° C in air)
1 to 3 hours), the adhesive portion of the crystal vibrating piece is plastically deformed and the stress can be relaxed. Within the range of A in the figure, standard specifications (frequency deviation ± 30 to 50 ppm,
It is a non-defective product when the frequency change in various reliability tests is ± 5 to 10 ppm). In the case of compressive stress, the crystal vibrating piece is bent, so there is no recovery force enough to plastically deform the adhesive, and the stress cannot be released.

[0012]

EFFECTS OF THE INVENTION The crystal resonator according to the present invention has a small frequency variation after encapsulation, and a large frequency and a small frequency are reduced. 2 No large series resonance resistance is present, and oscillation failure does not occur even if the drive level of the crystal unit is low. 3 The influence of external stress in reliability tests such as high temperature storage and impact tests is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a crystal resonator according to a conventional technique.

FIG. 2 is a sectional view of the embodiment of the present invention.

FIG. 3 is a sectional view for explaining the present invention.

FIG. 4 is a cross-sectional view illustrating a sealing mold that embodies the present invention.

FIG. 5 is a cross-sectional view before sealing.

FIG. 6 is a cross-sectional view after sealing.

FIG. 7 is an external view of a metal outer ring that is convex.

FIG. 8 is an external view of a metal outer ring with burrs.

FIG. 9 is an external view showing the state of the leads after sealing.

FIG. 10 is a stress distribution map.

FIG. 11 is a cross-sectional view of the crystal unit after sealing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal vibrating piece 2 Metal outer ring 3 Lead 3'Lead tip part 4 Flange part 4'Small protrusion 5 Sealing tube 6 Flange part 7 Flange part 8 Jig 9 Lower electrode 10 Sealing type

Claims (3)

[Claims] 1. A crystal vibrating piece is supported by the tip portions of a pair of leads, which penetrate through the metal outer ring and are insulated and sealed, and which project from the upper surface of the metal outer ring, and are integrally provided on the outer periphery of the metal outer ring. In the crystal unit that seals the open end of the sealing tube that covers the metal outer ring on the flange unit, the crystal unit has a structure in which no stress or tensile stress is applied to the crystal unit after the sealing. Characteristic crystal unit. 2. The crystal resonator according to claim 1, wherein the lower surface of the metal outer ring is curved in a concave shape in the longitudinal direction of the crystal resonator element. 3. A crystal vibrating piece is supported by the tips of a pair of leads, which penetrate through the metal outer ring and are insulated and sealed, and which project from the upper surface of the metal outer ring, and are integrally projected on the outer periphery of the metal outer ring. When sealing the crystal resonator that seals the open end of the sealing tube that covers the outer metal ring on the flange, the sealing die that abuts the lower surface of the outer metal ring bends in a convex shape. A method of manufacturing a crystal unit, which comprises encapsulating with a sealing mold.