JP3837265B2 - Crystal oscillator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crystal oscillator for surface mounting as an industrial technical field, and more particularly to a crystal oscillator having a concave portion on both sides and sealing a crystal piece by seam welding.
[0002]
[Prior art]
BACKGROUND OF THE INVENTION Crystal oscillators are widely used in various electronic devices including communication devices as a frequency and time reference source. In recent years, there has been a demand for crystal oscillators that are more compact and more reliable and economically advantageous.
[0003]
(Example of Prior Art) FIG. 4 is a cross-sectional view of a crystal oscillator for explaining a conventional example.
The crystal oscillator is configured by housing a crystal piece 2 and a circuit element 3 in a laminated ceramic container 1. The ceramic container 1 has side walls on both sides of the bottom wall and recesses on both sides. A metal ring 4 for seam welding is welded to the upper surface of one side wall. The crystal piece 2 has excitation electrodes on both main surfaces, and extends extraction electrodes on both sides of one end. The circuit element 3 includes an IC chip 3a in which an amplifier and the like constituting an oscillation circuit are integrated, and a large-capacitance capacitor 3b such as a bypass capacitor that is difficult to integrate.
[0004]
In such a case, first, both sides of one end portion of the crystal piece 2 are fixed and held on the bottom surface of one recess by the conductive adhesive 5. And the metal cover 6 is joined and sealed to the metal ring 4 by seam welding. Next, the characteristics of the crystal resonator (crystal piece 2) are inspected to eliminate defective products. Finally, the IC chip 3a is fixed to the bottom surface of the other concave portion of the ceramic container 1 having only a good crystal resonator as a crystal resonator by face-down bonding using bumps (not shown), and the capacitor 3b is fixed by a conductive adhesive (not shown). . Then, a resin material as the protective material 8 is filled.
[0005]
From these facts, it is economically advantageous because the quality of the crystal resonator can be determined before the expensive IC chip 3a is mounted. Also, since seam welding is used, the airtightness is improved compared to resin or glass sealing.
[0006]
[Problems to be solved by the invention]
(Problems of the prior art) However, the crystal oscillator having the above configuration has the following problems due to seam welding. That is, the seam welding is performed while a pair of rollers (not shown) are in contact with the metal cover 6 and the metal ring 4 and proceed. Therefore, the metal cover 6 is thermally expanded at the time of welding, and is cooled and contracted after sealing (arrow A in FIG. 4). The other recess extends in the opposite direction (arrow B). For this reason, stress is concentrated particularly on the corner P of the other concave portion due to expansion and contraction. Then, as shown in the bottom view of FIG. 5, there is a problem in that chips and cracks are generated from the corners to the outside, causing defects.
[0007]
(Object of the Invention) An object of the present invention is to provide a crystal oscillator by welding which prevents chipping and cracking.
[0008]
[Means for Solving the Problems]
The basic solution of the present invention is to make the radius of curvature R2 of the corner of the other recess larger than the radius of curvature R1 that contacts both sides of the corner of one recess in the ceramic container 1.
[0009]
[Action]
In the present invention, since the radius of curvature R2 of the corner of the other recess is increased, the stress during seam welding is dispersed. An embodiment of the present invention will be described below.
[0010]
FIG. 1 is a bottom view of a crystal oscillator for explaining an embodiment of the present invention. In addition, the same number is attached | subjected to the same part as a prior art example figure, and the description is abbreviate | omitted or abbreviate | omitted.
As described above, the crystal oscillator holds the crystal piece 2 in one concave portion of the ceramic container 1, seals the cover by seam welding, and accommodates the circuit element 3 of the IC chip 3a and the capacitor 3b in the other concave portion ( (See Fig. 4 above). Then, a radius of curvature (see FIG. 2) R2 in contact with both sides of each corner in the other recess is set to 0.3 mm, which is larger than the conventional R1 (0.25 mm). And the curvature radius of the corner | angular part of one recessed part shall be 0.25 mm as usual.
[0011]
That is, the curvature radius R2 of the other recess is made larger than the curvature radius R1 of the one recess. In such a thing, since each corner | angular part of the ceramic container 1 was made into an obtuse angle, stress disperse | distributed and it was able to prevent the generation | occurrence | production of the chipping and a crack after seam welding.
[0012]
[Other matters]
In the above embodiment, the other concave portion of the ceramic container 1 has a rectangular shape. However, for example, even when the groove 7 is provided on the opposite side to accommodate the circuit pattern or downsizing and the capacitor 3b is accommodated, the corner portion of the groove 7 is similarly provided. The curvature radius may be increased (FIG. 3). Further, although described as seam welding, for example, even in the case of beam welding, the metal cover is similarly expanded and contracted by heat, and can be applied to any welding that generates heat.
[0013]
The IC chip 3a is face-down bonding, but may be wire bonding or the like. Further, although the crystal piece is held at one end, it may be held at both ends, and these can be arbitrarily changed.
[0014]
【The invention's effect】
The present invention provides a crystal oscillator by seam welding in which the radius of curvature R2 of the corner of the other concave portion is larger than the radius of curvature R1 of the ceramic container contacting both sides of the corner of the concave portion, thereby preventing chipping and cracking. it can.
[Brief description of the drawings]
FIG. 1 is a bottom view of a crystal oscillator for explaining an embodiment of the present invention.
FIG. 2 is a diagram showing a radius of curvature as an embodiment of the present invention.
FIG. 3 is a bottom view for explaining another embodiment of the present invention.
FIG. 4 is a cross-sectional view of a crystal oscillator for explaining a conventional example.
FIG. 5 is a bottom view of a crystal oscillator for explaining a conventional example.
[Explanation of symbols]
1 container body, 2 crystal piece, 3 circuit element, 4 metal ring, 5 conductive adhesive, 6 metal cover, 7 groove, 8 resin material.

Claims (1)

A ceramic container comprising a bottom wall and a frame wall forming rectangular recesses on both sides of the bottom wall, and holding a crystal piece in the recess on the one main surface side and sealing the metal cover by welding. In the crystal oscillator in which the circuit element is accommodated in the recess on the other main surface side, the recess on the one main surface side and the other recess on the ceramic container are two on the inner side of the frame wall. R1 is a radius of curvature of the concave portion on the one main surface side, and R2 is a curvature radius of the concave portion on the other main surface side. Then, the radius of curvature R1 and the radius of curvature R2 satisfy R1 <R2.

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