JP3423255B2 - Surface mount crystal oscillator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mounted crystal oscillator (referred to as a surface-mounted oscillator) as an industrial technical field, and particularly to a crystal oscillator for surface mounting and a mounting substrate. The present invention relates to a method for bonding a surface-mounted oscillator in which the above method is bonded. (Background of the Invention) Surface mount oscillators are used, for example, as temperature-compensated oscillators in mobile communication devices such as mobile phones. In recent years, from the viewpoint of productivity, there is a surface-mounted oscillator in which a mounting substrate containing electronic components is bonded to the bottom surface of a crystal unit (see Japanese Patent Application Laid-Open No. 10-98151). (Example of Prior Art) FIGS. 5 and 6 are diagrams of a surface mount oscillator for explaining a conventional example of this kind. FIG. 5 is a sectional view, and FIG. 6 is an exploded view. The surface mount oscillator includes a crystal unit 1 and a mounting board 2. The crystal unit 1 accommodates a crystal piece 4 in a container body 3 made of a laminated ceramic. One end of the crystal blank 4 is electrically and mechanically connected and held by a conductive adhesive 11 or the like. The cover 5 is sealed by, for example, seam welding. The upper surface of the frame of the container body 3 has a metal ring 6 for welding, and the side and bottom surfaces have terminal electrodes 7 (abcd) connected to the excitation electrode of the crystal blank 4 and the like. The mounting substrate 2 is made of a laminated ceramic having a concave portion, and has an IC chip 8a and a capacitor 8 in the concave portion.
The electronic components 8 such as b. Then, the connection electrode 9 (abcd) is provided on the upper surface of the frame, and the mounting electrode 10 (abcd) is provided on the bottom and side surfaces.
Having. Then, the bottom surface of the crystal unit 1 and the opening surface side of the mounting substrate 2 face each other, and the terminal electrodes 7 (ab
cd) and the connection electrode 9 (abcd) of the mounting board 2 are joined by solder 12. In such a device, the crystal unit 1 and the mounting substrate 2 can be manufactured in parallel, and only good products need to be selected and joined. Therefore, the productivity can be increased and the defective rate in the finished product can be reduced. . [0006] (Problems of the prior art)
However, in the surface mount oscillator having the above-described configuration, the surface of the mounting substrate 2 is bonded to the bottom surface of the crystal unit 1 so as to face the opening surface. That is, since the bottom surface of the crystal unit 1 and the top surface of the frame are joined at the four corners where the terminal electrodes 7 and the joining electrodes 9 are formed, there is a problem that the joining area is small and the joining strength is reduced. Also, the smaller the planar outer shape, the more
The terminal electrodes 7 (abcd) and the connection electrodes 9 (abc
d) There is also a problem that the gap between them becomes small, and a conductive material such as the solder 12 causes an electric short circuit, which hinders a reduction in area (for example, less than 5 × 3.2 mm in a mobile phone or the like). (Object of the Invention) It is an object of the present invention to provide a surface mount oscillator which increases the bonding strength and reliably promotes miniaturization. According to the present invention, a basic solution is that a quartz oscillator and a mounting substrate are joined by an anisotropic conductive adhesive. According to the present invention, since the anisotropic conductive adhesive is applied, the entire opposing surfaces of the crystal unit and the mounting substrate can be joined. Less than,
An embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a surface mount oscillator for explaining an embodiment of the present invention. The same parts as those in the prior art are assigned the same reference numerals, and the description thereof will be simplified or omitted. As described above, the surface mount oscillator includes a crystal resonator 1 in which a crystal blank 4 is sealed and terminal electrodes 7 (abcd) are provided on the side and back surfaces.
And the mounting substrate 2 having the connection electrodes 9 (abcd) on the upper surface of the frame which becomes the opening surface in which the electronic component 8 is accommodated. In this embodiment, the conventional solder 1 is used.
In place of 2, the crystal unit 1 and the mounting substrate 2 are joined by the anisotropic conductive adhesive 13. Anisotropic conductive adhesive 13
Is formed by mixing conductive particles 13b having a uniform particle size into the adhesive 13a. Then, the conductive particles 13b are formed by thermocompression bonding.
Are arranged in a row, and only one direction between the upper and lower sides is conducted to join the two. The anisotropic conductive adhesive 13 in this example is affixed in the form of a tape to the upper surface of the opening of the mounting substrate 2 (FIG. 2). Then, they are bonded by thermocompression bonding so as to face the bottom surface of the crystal unit 1. Although the tape is provided with an opening in accordance with the frame, the tape may be flush with the workability of providing the opening. With such a configuration, since the entire upper surface of the frame is bonded, the bonding strength between the crystal unit 1 and the mounting substrate 2 can be increased. Then, electrical continuity between the terminal electrode 7 of the crystal unit 1 and the connection electrode 9 of the mounting substrate 2 is ensured, and the terminal electrodes 7 (abcd) and the connection electrode 9 (ab
cd) prevent electrical short circuit between them. Therefore, miniaturization (small area) is surely promoted. Second Embodiment FIG. 3 is a sectional view of a surface mount oscillator for explaining a second embodiment of the present invention. The description of the same parts as described above is omitted. In the first embodiment, the opening side of the mounting substrate 2 faces the bottom surface of the crystal unit 1, but in the second embodiment, the closed surface side of the mounting substrate 2 is bonded to face. That is, in the second embodiment, connection electrodes 9 (abcd) are formed at four corners of the closed surface of the mounting board 2 and mounting electrodes 10 (a) are formed at four corners of the upper surface of the frame on the opening side.
bcd). Then, a sheet-like anisotropic conductive adhesive 13 is attached to the entire closed surface, and the mounting substrate 2 is bonded to the bottom surface of the crystal unit 1 by thermocompression bonding. With such a configuration, since the closed surface of the mounting substrate 2 faces the bottom surface of the crystal unit and is entirely bonded by the anisotropic conductive adhesive 13, the bonding strength is further increased, Secure connection. [Other Matters] In the first and second embodiments, the mounting substrate 2
Each has a concave portion and accommodates the electronic component 8, but may be configured as shown in FIG. 4, for example. That is, the electronic component 8 may be fixed to the bottom surface of the crystal unit 1 and the mounting substrate 2 may be joined only by the anisotropic conductive adhesive 13 only as a frame. In this case, after confirming the characteristics of the crystal unit, the electronic component 8 is fixed to the back surface. In the second embodiment, the anisotropic conductive adhesive 13 is adhered to the entire surface of the mounting substrate 2. However, for example, the anisotropic conductive adhesive 13 is provided on the outer periphery of the mounting substrate 2 in the form of a frame. The portion may be provided with an insulating adhesive (not shown). In the first and second embodiments, the anisotropic conductive adhesive 13 may be provided only between the terminal electrode 7 and the connection electrode 9, and the other may be an insulating adhesive (not shown). Although the anisotropic conductive adhesive 13 is in the form of a sheet, it may be in the form of a liquid and applied pointwise with a dispenser or the like, and these can be arbitrarily selected. Further, although the crystal resonator accommodates a crystal piece in the concave container body 3, the container body 3 is flat and the concave cover may be sealed with resin or glass, and these forms are arbitrary. . Although the terminal electrode 7 and the connection electrode 9 each have four electrodes, the invention is applicable as long as it has two or more electrodes. In short, the purpose of the present invention is to obtain a surface mount oscillator in which the bonding strength is increased and the electrical connection is ensured by applying the anisotropic conductive adhesive 13 in response to miniaturization. Those based on such a purpose belong to the technical scope of the present invention, including any appropriate changes. According to the present invention, since the crystal unit and the mounting substrate are entirely bonded by an anisotropic conductive adhesive, the bonding strength between them is increased to ensure electrical connection and miniaturization. A surface-mount oscillator that promotes the above can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a surface mount oscillator illustrating a first embodiment of the present invention. FIG. 2 is a partially exploded view of the surface-mounted oscillator illustrating the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a surface mount oscillator illustrating a second embodiment of the present invention. FIG. 4 is a cross-sectional view of a surface mount oscillator illustrating another embodiment of the present invention. FIG. 5 is a cross-sectional view of a surface mount oscillator illustrating a conventional example. FIG. 6 is an exploded view of a surface mount oscillator illustrating a conventional example. [Description of Signs] 1 crystal resonator, 2 mounting board, 3 container body, 4 crystal piece, 5 cover, 6 metal ring, 7 terminal electrode, 8
Electronic components, 9 connection electrodes, 10 mounting electrodes, 11 conductive adhesive, 12 solder, 13 anisotropic conductive adhesive.

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Claims (1)

(57) [Claims] [Claim 1] A crystal resonator for surface mounting having an electrode on the back side by hermetically sealing and enclosing a crystal piece, and an electronic component in a frame joined to the back side of the crystal resonator. And the electrode and the electrode
In a surface-mounted crystal oscillator comprising a mounting substrate having connection electrodes that are connected to each other , a surface mounting crystal characterized by bonding the entire surface of the crystal resonator and the mounting substrate facing each other with an anisotropic conductive adhesive. Oscillator.