JPH0626317U - Surface mount piezoelectric resonator - Google Patents

Abstract

(57) [Summary] [Purpose] To improve heat resistance and vibration and shock resistance. [Configuration] A mounting electrode 22 is formed on the bottom surface of a ceramic plate-shaped base 21, a holding electrode 23 is formed on the upper surface of the base so as to be electrically connected to the mounting electrode, and a base portion welded to the holding electrode by series welding. An arm portion 24b is extended substantially parallel to the holding portion 24c by folding back the tip of the arm portion.
A holding member 24 in which a stopper 24d is provided by cutting and raising the outer edge of the holding portion, a piezoelectric piece 27 mounted and held on the holding portion of the holding member, and the upper surface of the base is airtight. And a bottomed box-shaped cover 28 for sealing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a surface-mounted piezoelectric resonator, and more particularly to improvement of a piezoelectric piece holding structure.

[0002]

[Prior art]

 Recently, piezoelectric resonators are widely used as a reference for frequency, time, etc. in various electronic devices. In particular, quartz oscillators that use quartz as a piezoelectric body are used in large quantities because they have excellent chemical and physical properties, and in addition to advances in manufacturing technology, they are inexpensive and have high performance. Conventionally, as such a crystal oscillator, one having a structure as shown in FIG. 5 is known. That is, a thin metal plate such as Kovar is press-molded to obtain an oval base 1. Then, two terminals 2 are inserted into the base 1 and filled with an insulating material such as molten glass to insulate and hold each other. Then, the base end of a holding member 3 having a spring property such as a piano wire is wound around and fixed to the tip of the terminal 2, and the clip 4 is formed at the tip. Then, the crystal piece 5 is inserted between the facing surfaces of the holding member 3, the peripheral portion thereof is held by the clip 4, and a conductive adhesive is applied to fix the quartz piece 5. The base 1 is covered with a bottomed tubular cover 6 having an oval cross section, and the opening edge of the cover 6 is hermetically sealed to the base 1 by resistance welding or the like. The crystal piece 5 is formed into a plate by cutting a crystal of quartz at a predetermined angle with respect to the crystal axis. Then, electrodes are formed on the front and back plate surfaces by vapor deposition or the like, and the electrodes are led out to both ends, respectively, and the lead-out ends are sandwiched by the clips 4 and electrically connected to the terminals 2.

However, in recent years, it has been desired to reduce the size and weight of electronic devices and automate the assembly process. For this reason, there is a tendency for electronic parts such as resistors, capacitors and integrated circuits to be of the surface mount type without lead terminals. When assembling electronic equipment using surface-mounting electronic components like this, for example, apply cream solder, etc. to the parts to be soldered, and use an automatic machine such as a chip mounter to place all components at the prescribed positions on the printed circuit board. To place. Then, the printed circuit board is passed through a tunnel furnace or the like to heat and melt the solder so that the mounting work of the components can be collectively performed in a short time. In the assembly of electronic equipment using such surface-mounted electronic components, lead holes are drilled at specified positions on the printed circuit board, and the lead terminals of the components are inserted and soldered as before. It can be automated more easily and can be smaller in size and lighter in weight than those mounted by using the same method. For this reason, piezoelectric vibrators used for such electronic devices are also desired to be surface-mounted type without lead terminals. FIG. 6 is an assembled perspective view showing an example of such a surface-mounted piezoelectric vibrator. A mounting electrode (not shown) is formed on the bottom surface of a plate-shaped ceramic base 11, and this mounting electrode is used as a conductive pattern of a printed circuit board. It is soldered to and mounted. Then, the holding electrode is formed on the upper surface of the base 11 by being electrically connected to the mounting electrode. Then, a pair of holding members 12 formed by molding a thin metal plate are fixed to the above-mentioned holding electrodes by a conductive adhesive having a good heat resistance, for example, a polyimide-based adhesive, and electrical conduction is achieved. Then, the piezoelectric piece 13 is placed on the holding member 12, and a conductive adhesive or the like is applied and held. The piezoelectric piece 13 is formed, for example, by cutting a crystal of artificial quartz at a predetermined angle with respect to the crystal axis to form a plate, and forming an electrode on the plate surface. Then, the opening of the bottomed box-shaped cover 14 is fixed to the plate surface of the base 11 with molten glass, an adhesive or the like to hermetically seal. However, in such a structure, an adhesive is used to fix the holding member 12 to the base 11. For this reason, sufficient mechanical strength could not be obtained, and the holding member 12 sometimes came off the base 11 when violent vibration, impact, etc. acted from the outside. In addition, this kind of adhesive also has insufficient heat resistance, and it was necessary to severely limit the heating conditions when soldering the mounting electrodes when mounting on a printed circuit board or the like. Further, this type of conductive adhesive generates gas when it is heated to a high temperature when it is mounted on a printed circuit board, and this component adheres to the surface of the piezoelectric piece 13 and remarkably impairs resonance characteristics. There was a problem of deterioration.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a surface-mounted piezoelectric resonator which has improved heat resistance and excellent vibration and shock resistance characteristics.

[0005]

[Means for Solving the Problems]

 According to the present invention, a mounting electrode is formed on the bottom surface of a ceramic plate-shaped base, a holding electrode is formed on the upper surface of the base so as to be electrically connected to the mounting electrode, and the holding electrode is welded by series welding. A holding member that extends the arm in parallel and folds back the tip of the arm to form a holding part, cuts and raises the outer edge of this holding part, and mounts it on the holding part of this holding member. And a bottomed box-shaped cover that hermetically seals the upper surface of the base.

[0006]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to an assembled perspective view shown in FIG. 1 and a side sectional view shown in FIG. Reference numeral 21 in the figure denotes a ceramic base having a thickness of 1.0 mm and a size of 12.0 mm × 5.5 mm, for example. Then, at least two mounting electrodes 22 are formed on the bottom surface of the base 21 for mounting on a printed circuit board or the like. The mounting electrode 22 is, for example, a metal thin film formed by a metallizing process. A pair of holding electrodes 23 are formed on the upper surface of the base 21 so as to be electrically connected to the mounting electrodes 22. The holding electrode 23 is also a metal thin film formed by, for example, a metallizing process. Each of the electrodes 22 and 23 may be formed by, for example, molding a thin metal plate into a predetermined shape and embedding it in the base 21, and using one end of the thin metal plate as the mounting electrode 22 and the other end as the holding electrode 23. Good. Then, a holding member 24 formed by forming a thin metal plate of nickel silver or the like having a thickness of about 0.05 mm into a predetermined shape is welded to each holding electrode 23 by series welding. The holding member 24 includes a base portion 24a to be welded to each of the holding electrodes 23, two arm portions 24b extending outward from the base portion 24a substantially in parallel, and two arm portions 24b. A holding portion 24c provided at the tip and formed by folding back the tip portion, and a stopper 24d formed by further cutting and raising the outer edge of the holding portion 24c are provided. It should be noted that the holding members 24 may be formed by, for example, a strip-shaped metal thin plate having a thickness of about 0.05 mm arranged in a row at regular intervals by etching or the like, as shown in the plan view of the lead frame 25 shown in FIG. Good. When the holding member 24 is formed on the lead frame 25 in this manner, the holding member 24 having a very small shape is accurately positioned and welded to the base 21 by corresponding to the position of the holding member 24 on the base 21. be able to. Therefore, the holding portion 24c of the holding member 25 is folded back in advance, and the stopper 25d is further cut and raised. Then, for example, as shown in the side view of FIG. 4, the base 21 is sent out directly below the welding electrode 26 one by one, the lead frame 25 is positioned on this, and the holding member provided on the lead frame 25 by the welding electrode 26. The base portion 24a of 24 is pressed down to the holding electrode 23 of the base 21 and a large current is instantaneously passed to perform series welding to weld both. By sequentially performing the series welding in this manner, the holding member 24 can be welded to the base 21 by continuous flow work. It should be noted that feed holes 25a may be provided on both sides of the lead frame 25 at regular intervals, and feed pawls (not shown) may be meshed with the feed holes 25a so as to be advanced intermittently. Then, the holding member 24 is welded to the base 21 and then cut off from the lead frame 25 with a press or the like. Then, the piezoelectric piece 27 is placed on the holding portion 24c of the holding member 24, and a conductive adhesive is applied to hold it mechanically and to achieve electrical continuity. At this time, the piezoelectric piece 27 can be accurately and easily positioned at a predetermined position by the stopper 24d provided outside the holding member 24. A bottomed box-shaped cover 28 is covered on the upper surface of the base 21, and the opening of the cover 28 is airtightly fixed to the plate surface of the base 21 by using an adhesive, molten glass or the like.

With such a configuration, the holding member 24 made of a thin metal plate is folded back in half at the tip of the arm portion 24b, the base portion 24a is welded to the holding electrode 23 by series welding, and the other holding portion is held. The piezoelectric piece 25 is placed on the portion 24c. Therefore, since the arm portion 24b can be narrow and long, the elasticity of the member can be fully utilized. Therefore, no mechanical strain occurs when the conductive adhesive is applied and solidified to hold the piezoelectric piece 27 by the holding member 24. Since the piezoelectric member 27 is held by the holding member 24 having high elasticity, the piezoelectric member 27 is not damaged or changed in characteristics due to external vibration, impact, etc. Can be obtained. Since the holding member 24 is welded to the holding electrode 23 by series welding, its mechanical strength is about twice as high as that using an adhesive, and gas is generated even when it is heated during mounting. Good aging characteristics can be obtained without any generation.

[0008]

[Effect of device]

 As described in detail above, according to the present invention, it is possible to provide a surface-mounted piezoelectric resonator that has good vibration resistance and shock resistance, is suitable for mass production, and has a small shape.

[0009]

[Brief description of drawings]

FIG. 1 is an assembled perspective view showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the embodiment shown in FIG.

FIG. 3 is a plan view showing a lead frame having a holding member according to an embodiment of the present invention.

FIG. 4 is a side view illustrating series welding of the present invention.

FIG. 5 is an assembled perspective view showing an example of a conventional crystal resonator.

FIG. 6 is an assembled perspective view showing an example of a conventional surface mount type crystal unit.

[Explanation of symbols]

 21 Base 22 Mounting Electrode 23 Holding Electrode 24 Holding Member 24a Base 24b Arm 24c Holding 24d Stopper 26 Welding Electrode 27 Piezoelectric Piece 28 Cover

Claims (1)

[Scope of utility model registration request] 1. A ceramic plate-shaped base, a mounting electrode formed on the bottom surface of the base, a holding electrode formed on the upper surface of the base so as to be electrically connected to the mounting electrode, and a series welding on the holding electrode. A holding member in which an arm portion is extended from the welded base portion substantially in parallel, a tip of the arm portion is folded back to form a holding portion, and an outer edge portion of the holding portion is cut and raised to project a stopper, and a holding member Of the surface mount type, comprising: a piezoelectric piece mounted and held on a base; and a bottomed box-shaped cover that covers the upper surface of the base and has an opening airtightly fixed to the plate surface of the base. Piezoelectric resonator.