JP3496922B2 - Manufacturing method of piezoelectric vibrator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a piezoelectric vibrator using laser welding. [0002] A conventional method of manufacturing a piezoelectric vibrator using laser welding will be described below. FIG. 6 shows a sectional view of the piezoelectric vibrator 1. The piezoelectric vibrator 1 has an airtight terminal 25 as shown in FIG.
, A piezoelectric oscillating piece 22 and a case 21.
A piezoelectric vibrating piece 22 having an airtight terminal 25 having a lead 27 insulated by a glass 26 and an electrode 23 made of a metal such as Au or Ag by means of vapor deposition, sputtering or the like.
g. Fix to the lead 27 with paste 24 or the like. [0003] Next, the frequency is adjusted by shaving the metal of the electrode 23 or adding a heavy metal. Then, the case 21 is covered and the airtight terminals 2
The joining portion of the case 5 and the case 21 is sealed by laser welding, and the piezoelectric vibrator 1 is manufactured. A laser having a small power such as a YAG laser is sufficient. FIG. 7 shows a partially enlarged view of a conventional laser welding machine. The nitrogen box 5 is maintained at an oxygen concentration of 1% or less. The piezoelectric vibrator 1 is chucked to the chuck jig 2.
The laser is applied to the piezoelectric vibrator 1 through the glass 4 from the laser head 3 attached to the upper part of the nitrogen box 5. FIG. 8 shows a conventional chuck portion. The piezoelectric vibrator 1 is chucked to the chuck jig 2, and a laser beam is irradiated from above on the joint between the airtight terminal 25 and the case 21. [0007] However, in the conventional technique, high heat is applied to the sealing portion because the metal of the case and the hermetic terminal is melted and sealed during the laser welding. For this reason, there has been a problem that the frequency of the piezoelectric vibrator greatly changes. In addition, there is a problem that cracks occur between the lead and the glass, resulting in a leak. Further, during welding, welding debris becomes soot and scatters in the nitrogen box, and adheres to a piezoelectric vibrator, glass, and the like.
Cleaning was very difficult. The present invention solves such problems. (1) In the laser welding sealing of a piezoelectric vibrator using a hermetic terminal and a case, nitrogen gas or non- coercive in active gas atmosphere
In sauce was BOX, and, in covering <br/> a nozzle for blowing nitrogen gas or inert gas which is attached near the jig and the jig for chucking the piezoelectric vibrator and the piezoelectric vibrator Enclosing, spraying the nitrogen gas or the inert gas to the welded portion from the nozzle, cooling the welded portion, and simultaneously performing the welding while forcibly exhausting the welding debris from the cover by the pump using the pump. Features. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. [Embodiment] An embodiment of the present invention will be described with reference to a partially enlarged view of FIG. The piezoelectric vibrator 1 is the same as that described with reference to FIG. The piezoelectric vibrator 1 is chucked to the chuck jig 2. The inside of the nitrogen box 5 is filled with 99% or more of nitrogen or an inert gas. Oxygen concentration 1 in nitrogen BOX5
% And does not oxidize, but has no special cooling effect. The inside of the nitrogen box 5 may be an inert gas instead of the nitrogen gas. The laser is applied to the piezoelectric vibrator 1 through the glass 4 from the laser head 3 mounted on the nitrogen box 5.
Is irradiated. A cooling nozzle 6 for cooling is attached near the chuck jig 2. A cover 7 surrounds the inert gas blowing portion. The chuck jig 2 rotates simultaneously with the laser welding, and seals the outer periphery of the piezoelectric vibrator 1 by laser welding. Inert gas is blown from the cooling nozzle 6 at the same time as laser irradiation, and laser welding is performed while cooling to suppress the temperature rise of the piezoelectric vibrator 1 during welding. Nitrogen or the like is used as the inert gas to be blown. FIG. 2 shows a cooling unit according to the present invention. It is preferable that the cooling nozzle 6 be installed as close as possible to the piezoelectric vibrator. As the distance increases, the flow rate of the inert gas decreases,
The cooling effect is also reduced. Further, if the distance is far, a large amount of the inert gas is used, which is wasted. It is desirable to blow the inert gas from the side of the piezoelectric vibrator 1 as shown in FIG. Since the laser beam is irradiated from above, it is more effective to blow an inert gas from the side to cool the vicinity of the welded portion and the entire piezoelectric vibrator 1. If the temperature of the inert gas to be blown is too high, the cooling effect will be lost, and if it is too low, the temperature of the welded portion will be too low, so that the melting will not be performed uniformly, causing holes and leaks. For this reason, it is necessary to control the temperature of the inert gas in the range of 5 ° C to 50 ° C. FIG. 3 is a sectional view of a welded portion of the piezoelectric vibrator 1. Since the distance between the welding portion 8 and the glass 26 is short, heat during welding is easily transmitted. When the case 21 and the airtight terminal 25 are melted by a laser, a temperature close to 1400 ° C. is generated because an iron or nickel-based metal is used. Since the irradiation time of the laser beam is short, the temperature of the portion other than the melting portion 8 becomes 1000 ° C. or less.
In particular, since the glass 26 is vulnerable to rapid heat and rapid cooling, the glass 26 peels off from the interface with the metal, and easily leaks. Therefore, simultaneously with the laser welding, the welded portion 8 and the entire piezoelectric vibrator 1 are cooled with an inert gas to prevent leakage near the glass 26. FIG. 4 shows a characteristic diagram of the present piezoelectric vibrator. The vertical axis represents the amount of change in frequency, and the horizontal axis represents time. The piezoelectric vibrator of the present invention is cooled during laser welding, so that heat is hardly applied to the inside, so that a change in frequency is small even if time passes. On the other hand, the frequency of a conventional piezoelectric vibrator without cooling changes negatively and rapidly over time. This is because gas, moisture, etc. attached to the case 21, the piezoelectric oscillating piece 22, etc. arrive or separate by heating,
This is because after welding, it adheres to the piezoelectric oscillation piece 22. FIG. 5 shows a chuck portion of the present invention. By attaching the cover 7 in the vicinity of the chuck jig 2, a pump (not shown) is forcibly exhausted to the outside so that welding chips generated during laser welding are not scattered. Cover 7
In the upper part, a hole into which a laser beam is inserted, and in the front, a hole through which a piezoelectric vibrator can be supplied to and discharged from the chuck jig 2. Nitrogen BOX5 by evacuating simultaneously with laser welding
Welding waste inside can be forcibly discharged to the outside. By confining the welding debris in the cover 7 as much as possible and evacuating, the welding debris is prevented from being scattered in the nitrogen BOX 5, so that the contamination by soot is extremely reduced. According to the present invention, in a laser welding sealing of a piezoelectric vibrator using a hermetic terminal and a case in a nitrogen gas atmosphere,
In addition, an inert gas is blown onto the welded portion, and welding is performed while cooling, thereby suppressing a rise in the temperature of the welded portion. Thus, the frequency change as the piezoelectric vibrator can be suppressed, and the characteristics can be improved. Further, it is possible to eliminate the leak due to the peeling of the interface between the glass and the metal of the hermetic terminal due to the influence of heat. By attaching a cover in the vicinity of the welded portion, the scattering of welding dust into the nitrogen BOX can be extremely reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially enlarged view of a laser welding machine used for manufacturing the piezoelectric vibrator of the present invention. FIG. 2 is a partially enlarged view showing a cooling unit of the present invention. FIG. 3 is a sectional view of a welded portion of the piezoelectric vibrator. FIG. 4 is a characteristic diagram of a piezoelectric vibrator. FIG. 5 is a partially enlarged view of a chuck portion used for manufacturing the piezoelectric vibrator of the present invention. FIG. 6 is a sectional view of a piezoelectric vibrator. FIG. 7 is a partially enlarged view of a laser welding machine used for manufacturing a conventional piezoelectric vibrator. FIG. 8 is a partially enlarged view of a chuck portion used for manufacturing a conventional piezoelectric vibrator. [Explanation of reference numerals] 1. Piezoelectric vibrator 2. Chuck jig Laser head section 4. Glass5. Nitrogen BOX Cooling nozzle7. Cover 8. Weld 21. Case 22. Piezoelectric oscillation piece 23. Electrode 24. Ag paste 25. Airtight terminal 26. Glass 27. Lead

Claims (1)

(57) In the laser welding the sealing of the piezoelectric vibrator with Claims 1. A hermetic terminal and the case, a nitrogen gas or BOX in was maintained at an inert gas atmosphere, and the piezoelectric surrounds a nozzle for blowing vibrator before <br/> Symbol nitrogen gas or inert gas, fitted with a piezoelectric vibrator in the vicinity of the jig and the jig for chucking a cover, wherein the weld from the nozzle A method for manufacturing a piezoelectric vibrator, comprising blowing nitrogen gas or the inert gas to cool the welded portion, and simultaneously performing welding while forcibly exhausting welding waste from the cover using a pump. .