JP2005244703A - Base substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a base substrate capable of confirming improved junction intensity with a user substrate and the quality at the junction portion, when the base substrate becomes smaller in size following miniaturization of electronic components such as a crystal oscillator. <P>SOLUTION: In the base substrate for surface mounting, having a plane electrode as an external terminal which conducts between the internal and external sides of a sealed vessel for housing a piezoelectric element plate, the plane electrode is thickened by a laminate structure with metallization or addition of silver solder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface electrode structure of a base substrate on which a piezoelectric element plate used for an airtight container for housing an extremely miniaturized piezoelectric component used mainly in the field of mobile communication such as a wireless communication device and a cellular phone is mounted.

  In recent years, with the spread of computers and mobile phones, the functions and performance have been increasing day by day, and at the same time, the weight reduction, thinning, and low profile have changed at an abrupt speed in developing mobile devices. The industry is addressing this as one of the challenges. At the heart of most electronic devices such as computers and mobile phones, oscillators and oscillators that generate clock signals and local oscillator signals are indispensable components. Along with the trend of low profile, the oscillator itself is also strongly demanded to be downsized (light weight, thin, low profile, low volume).

  In general piezoelectric vibrators and piezoelectric oscillators, a printed pattern for mounting piezoelectric elements and drive circuits is placed on a multilayer substrate using ceramic materials or organic materials, and a conductive pattern is placed on the multilayer substrate by multilayer printing. This is configured as a sealed container in which semiconductor components such as a capacitor, resistor, and integrated circuit constituting a piezoelectric element plate and an oscillation circuit are housed as necessary components on the same plane of the substrate and sealed in an airtight atmosphere.

In this way, recent piezoelectric parts (piezoelectric vibrators, piezoelectric oscillators, surface acoustic wave devices) are used by being mounted on a small user board. At the same time, user products have become smaller and thinner. The thickness (height) is currently forced to have a very low profile.
Japanese Patent Application Laid-Open No. 07-201650 JP 2002-141466 A

  As described above, recent piezoelectric parts have been rapidly reduced in size and height. Further, in the piezoelectric component, the product outer dimension so far, which has been 3 mm × 2.5 mm, has been reduced to about 1.0 mm square. At the same time, since the height is reduced to 0.5 mm, it is difficult to manufacture a base substrate constituting a sealed container as in the prior art and mount a piezoelectric component on the base substrate. It is in the present situation.

  Therefore, for example, before processing the base substrate in the state of a wafer of ceramic material and obtaining the base substrate in one piezoelectric component unit, the piezoelectric component is mounted on the wafer-like base substrate by so-called batch processing, and then The current miniaturization was supported by cutting into piezoelectric parts.

  However, if the piezoelectric component is miniaturized and the outer dimensions are reduced, the base substrate is processed from the wafer state, and until now, the substrate is divided by the piezoelectric component unit of the wafer-like base substrate. Through holes were provided on the front and back of the metal, and the inner wall of this through hole could be metallized. However, because the external dimensions were reduced, conventional through hole processing and shapes could not be obtained, and the user There arises a problem that it becomes difficult to confirm the strength and mounting state when mounted on the substrate.

  As described above, with the base substrate of the present invention, it is possible to easily check the mounting strength and mounting state when mounting the piezoelectric component on the user substrate, thereby improving the mounting quality when mounted on the user substrate.

  The present invention relates to a surface mount base substrate which is an airtight container for housing a piezoelectric element plate and has an electrode that conducts the inside and outside of the airtight container as an external terminal. The surface electrode is added with metallization or silver solder. Thus, the base substrate is characterized in that the thickness of the surface electrode is increased in a laminated structure.

  In short, when a base substrate on which a piezoelectric base plate, which is a part of a sealed container, is conventionally formed and used in a wafer state, the external dimensions of the piezoelectric component have been large so far that the piezoelectric component is in the wafer state. It was possible to lay out in units. For this reason, in the piezoelectric component unit, the metallization processing of the through hole and the inner wall disposed on the side surface of the substrate could be performed. However, since the outer dimensions have recently been reduced, it is difficult to perform the above-described through hole and metallization processing. It has become.

  Therefore, the surface to be formed on the base substrate to ensure the same mounting strength as when mounting piezoelectric parts using a conventional base substrate on the user substrate and to confirm the bonding state at the time of mounting. Increase the surface area where the surface electrode is exposed in order to secure overall bonding strength when the electrode part is thickened with a laminated structure, for example, when the surface electrode is fixed and connected with a conductive adhesive or solder. It is intended.

  As for securing the surface area where the surface electrode is exposed, it is conceivable to increase the area relative to the base substrate. However, as described in the prior art, the external dimensions of the piezoelectric component have become extremely small. Since the surface electrode that can be formed on the substrate is also limited, securing the thickness of the surface electrode can increase the bonding strength when actually mounted on the user substrate.

  Further, since the gap between the user substrate and the base substrate can be secured by increasing the thickness of the surface electrode, the reliability in confirming the bonding state of the surface electrode can also be improved. The sealed container described here accommodates a piezoelectric vibrator, a piezoelectric oscillator, and a surface acoustic wave.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In each figure, the same numerals indicate the same objects. The wiring on the base substrate and the electrodes of the piezoelectric element plate are not shown.

  FIG. 1 is a side sectional view of the surface mounting component of the present invention. As shown in FIG. 1, a closed container 2 is constituted by a base substrate 4 and an upper portion thereof, for example, a lid member such as metal. The piezoelectric element plate 1 is electrically connected by a gold bump or a conductive adhesive. The surface electrode 3 has a laminated structure of a first surface electrode and a second surface electrode.

  FIG. 2 is an image of a wafer-like base substrate 4 and shows a state where, for example, a 3-inch square ceramic substrate is divided in units of external dimensions of piezoelectric components. FIG. 2A shows an overall view of the wafer state, and FIG. 2B is a perspective view showing a base substrate 4 as a single piezoelectric component. On the other hand, FIG. 4 shows a base substrate 4 in a wafer state as a conventional example.

  As can be seen from FIG. 4, since the outer dimensions of the piezoelectric component are large and the outer dimensions are small, it is not possible to form a through hole on the side surface of the base substrate 4 for conducting the base board 4 in particular. It seems to understand. Therefore, in FIG. 2B, it can be seen that there is no metallized portion on the side surface of the base substrate 4 when viewed as a single piezoelectric component.

  FIG. 3 shows one of the divided base substrates 4 of the present invention as a single piezoelectric component, paying attention to the surface electrode 3. As shown in FIG. 3A, there is a significant difference from the conventional case, and there is no metallized portion on the side surface, and the surface electrode to be mounted on the user board has a laminated structure of the first surface electrode and the second surface electrode. Is added. In order to add thickness, the metallized layer is thickened or a brazing material is added.

  FIG. 3B is an enlarged view of FIG. 3A, and is drawn by changing the areas of the first surface electrode and the second surface electrode as shown in FIG. In order to improve the bonding strength with the user substrate, the outer shape of the first electrode is changed as a devised shape of the surface electrode 3. The background of the present invention is that the external dimensions of the surface-mount type quartz crystal resonator are 2 mm × 1.6 mm and are reduced in size and weight. Therefore, instead of manufacturing the base substrate 4 individually, which is a conventional idea, the handling of the case where the outer dimensions are reduced is improved by cutting a single wafer-like base substrate 4 into smaller pieces. is there. In short, a crystal resonator is assembled in the form of a single wafer-like base substrate 4 and then cut into individual crystal resonators.

  In the present invention, a vibrator using a piezoelectric material is mainly described. However, the present invention can also be applied to an oscillator and an elastic surface element used for communication equipment.

It is sectional drawing of the surface mounted component using the base substrate obtained by this invention. It is a conceptual diagram of the base substrate used by this invention. It is the figure which paid its attention to the surface electrode part of the base substrate of this invention. It is a conceptual diagram of the base substrate used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric base plate 2 Airtight container 3 Surface electrode 4 Base substrate

Claims (2)

In a surface mount base substrate having a surface electrode as an external terminal, an electrode that conducts the inside and outside of the sealed container in a sealed container containing a piezoelectric element plate,
A base substrate characterized in that metal oxide or silver solder is added to the surface electrode to increase the thickness of the surface electrode in a laminated structure. The base container according to claim 1, wherein the base substrate stores a piezoelectric vibrator, a piezoelectric oscillator, and a surface acoustic wave.

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