JP2009239475A - Surface mounting piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mount type piezoelectric oscillator corresponding to a reduction in size and height while eliminating waste of a mounting area and a manufacturing method thereof.
A surface-mount piezoelectric oscillator having an insulating base 1 for housing a piezoelectric diaphragm 3 and an integrated circuit element 2, wherein the base is a side wall portion, a first housing portion 10a, and the first housing. A step part 10c connected to the side wall part of the part, a second storage part 10b disposed on the top surface of the first storage part and the step part, and a wiring pattern is formed on the front and back surfaces. The upper surface side of the plate-like circuit board 4 and the piezoelectric diaphragm, the bottom surface side of the circuit board and the integrated circuit element are respectively bonded by a conductive bonding material, and the wiring pattern on the upper surface of the stepped portion and the A part of the wiring pattern on the bottom surface side of the circuit board is bonded with a conductive bonding material.
[Selection] Figure 1

Description

  The present invention relates to a surface-mount piezoelectric oscillator in which a piezoelectric diaphragm and an integrated circuit element are mounted on an insulating base, and particularly to improve the package structure of a surface-mount piezoelectric oscillator.

  A piezoelectric oscillator using a piezoelectric diaphragm such as a crystal can stably obtain a highly accurate oscillation frequency, and is therefore used in various fields as a reference frequency source for electronic devices and the like. In a surface-mounted piezoelectric oscillator, a ceramic multilayer substrate is used as an insulating base, an integrated circuit element for an oscillation circuit is disposed in a housing portion of the base, and a crystal diaphragm is supported and fixed above the integrated circuit element. , Hermetically sealed. Such a configuration has a relatively small number of parts due to customization of the integrated circuit element, is a simple configuration, and contributes to cost reduction.

Such an integrated circuit element is connected to a wiring pattern formed on a base using a wire bonding method, or a face-down bonding method (hereinafter referred to as “FCB”) through a metal bump (Au or the like). ) Is electrically connected to a piezoelectric vibrator, a terminal electrode, or the like (see, for example, Patent Document 1 below).
JP 2004-356687 A

  Currently, electronic devices are being miniaturized, and along with this miniaturization, the surface-mount piezoelectric oscillator as described above is also being miniaturized. Therefore, for example, in the surface mount type piezoelectric oscillator as shown in Patent Document 1 described above, a planar area for mounting a piezoelectric diaphragm or an integrated circuit element is narrowed, or the height of the storage portion is made as low as possible. It is requested to do.

  Further, since the size of the piezoelectric diaphragm disposed on the upper portion is limited according to the size of the storage portion for storing the integrated circuit element, the mounting area is likely to be wasted. The electrical connection region between the integrated circuit element and the base and the electrical connection region between the piezoelectric diaphragm and the base are also formed separately, leading to an increase in the mounting region.

  SUMMARY OF THE INVENTION In order to solve the above-described problems, an object of the present invention is to provide a surface-mount type piezoelectric oscillator and a method for manufacturing the same that can be reduced in size and height while eliminating waste in the mounting area.

  In order to achieve the above object, according to the surface mount piezoelectric oscillator of the present invention, as shown in claim 1, a piezoelectric diaphragm on which an excitation electrode and an extraction electrode are formed, and a wiring pad is formed on one main surface. A surface-mount piezoelectric oscillator having an integrated circuit element and having an insulating base for storing these, wherein the base has a side wall portion and a storage portion on the top surface side, and a terminal electrode on the bottom surface side, The accommodating portion accommodates the first accommodating portion in which the integrated circuit element is accommodated on the inner bottom surface, the step portion connected to the side wall portion of the first accommodating portion, the piezoelectric diaphragm, and the first accommodating portion. A wiring pattern on the upper surface side of the plate-like circuit board on which the wiring pattern is formed on the front and back surfaces and the piezoelectric diaphragm Are connected to each other by a conductive bonding material. The bottom surface side wiring pattern and the wiring pad of the integrated circuit element are bonded with a conductive bonding material, and the piezoelectric diaphragm and the integrated circuit element are electrically connected to each other only by the circuit board, The wiring pattern on the circuit board is led out to the terminal electrode of the base by bonding the wiring pattern on the top surface of the stepped portion and a part of the wiring pattern on the bottom surface side of the circuit board with a conductive bonding material. It is characterized by.

  With the above configuration, the plate-like circuit board in which the piezoelectric vibration plate and the integrated circuit element are bonded to the front and back surfaces by the conductive bonding material is bonded by the conductive bonding material only at the step portion of the base. Separately connecting the electrical connection area with the base, the electrical connection area between the integrated circuit element and the base, and the electrical connection area between the piezoelectric diaphragm and the integrated circuit element. It is no longer necessary to form the base, and the base can be reduced in size and height.

  In addition, the size and holding form of the piezoelectric diaphragm that can be mounted according to the plane area of the first storage unit and the plane area of the integrated circuit element are not limited, and the width of the design of the piezoelectric diaphragm used for the piezoelectric oscillator is eliminated. Will spread dramatically and waste will be eliminated. In particular, even a piezoelectric diaphragm smaller than the first housing can be easily mounted, and the circuit board does not support the piezoelectric diaphragm and the piezoelectric diaphragm is not tilted and mounted in the first housing.

  Furthermore, the thermal adverse effects of the integrated circuit elements that generate heat during driving are transmitted to the piezoelectric diaphragm in a more reduced state due to the interposition of the circuit board, and the electrical characteristics such as frequency temperature characteristics are degraded. Less is.

  According to a second aspect of the present invention, in addition to the above-described configuration, the main surface of the integrated circuit element where the wiring pads are not formed is mechanically bonded to the inner bottom surface of the first storage portion of the base. The wiring pattern on the bottom surface side of the circuit board, the wiring pad of the integrated circuit element, and the wiring pattern on the top surface of the step portion of the base and the wiring pattern on the bottom surface side of the circuit board are joined by metal bumps. It is characterized by becoming.

  With the above configuration, in addition to the above-described effects, the wiring pattern on the bottom surface side of the circuit board, the wiring pad of the integrated circuit element, and the wiring pattern on the top surface of the stepped portion of the base are joined only by metal bumps. Therefore, compared to the case of bonding using conductive resin adhesive or brazing material, each bonding area is space-saving and reliable electromechanical bonding can be performed, and unnecessary gas is generated during bonding. There is no. For this reason, the area of the step portion can be further reduced, and not only can the size of the base be further reduced, but also the electrical performance of the piezoelectric oscillator is not adversely affected, so that the aging characteristics can be improved.

  In addition, compared to a configuration in which the integrated circuit element and the base are connected using wire bonding, a space that becomes a gap so that other members such as a piezoelectric diaphragm and a circuit board are not in direct contact with the upper portion of the wire bonding becomes unnecessary. It becomes the structure that it is easy to cope with the low profile of the base.

  Furthermore, in the present invention, since the circuit board is joined to the upper portion of the first storage portion of the base via the step portion of the base and the integrated circuit element, the mechanical bending strength of the base can be increased. In particular, by increasing the bending strength of the base, it is possible to suppress cracks in the base that are likely to occur when hermetic sealing is performed by local heating such as seam sealing or beam sealing.

  In addition to the above-described configuration, it is preferable to use metal bumps of the same material and the same shape. With such a configuration, the bonding strength of the metal bumps between the wiring pattern on the bottom side of the circuit board, the wiring pad of the integrated circuit element, and the wiring pattern on the top surface of the stepped portion of the base can be made uniform. Moreover, since the bonding conditions are the same by using metal bumps of the same material, it is possible to apply ultrasonic waves from the top of the circuit board and simultaneously perform FCB bonding, and there is no variation in strength at that time.

  According to a third aspect of the present invention, in addition to the above-described configuration, the main surface of the integrated circuit element where the wiring pads are not formed is mechanically bonded to the inner bottom surface of the first storage portion of the base. A wiring pattern on the bottom side of the circuit board and a wiring pad of the integrated circuit element are joined by metal bumps, and a wiring pattern on the top surface of the stepped portion of the base and a wiring pattern on the bottom side of the circuit board, Are bonded with a conductive resin adhesive or a metal brazing material.

  With the above configuration, in addition to the above-described effects, the wiring pattern on the bottom surface side of the circuit board and the wiring pad of the integrated circuit element are joined by metal bumps, and the wiring pattern on the top surface of the stepped portion of the base Since the wiring pattern on the bottom side of the circuit board is joined with a conductive resin adhesive or a metal brazing material, the unevenness of the flatness of the stepped portion of the base and the gap of the stepped portion of the circuit board and the base are electrically conductive. More reliable electromechanical joining can be achieved by absorbing in the joining region of the conductive resin adhesive or metal brazing material. In particular, when a conductive resin adhesive is used, the impact resistance is improved because the external impact on the piezoelectric diaphragm is softened.

  In addition, compared to a configuration in which the integrated circuit element and the base are connected using wire bonding, a space that becomes a gap that prevents other members such as a piezoelectric diaphragm and a circuit board from directly contacting the upper portion of the wire bonding becomes unnecessary. It becomes the structure that it is easy to cope with the low profile of the base.

  Furthermore, in the present invention, since the circuit board is joined to the upper portion of the first storage portion of the base via the step portion of the base and the integrated circuit element, the mechanical bending strength of the base can be increased. In particular, by increasing the bending strength of the base, it is possible to suppress cracks in the base that are likely to occur when hermetic sealing is performed by local heating such as seam sealing or beam sealing.

  In order to achieve the above object, according to the method of manufacturing a surface-mounted piezoelectric oscillator of the present invention, as shown in claim 4, a piezoelectric diaphragm having an excitation electrode and an extraction electrode, and a wiring pad on one main surface An integrated circuit element formed with a first storage part in which the integrated circuit element is stored, a step part connected to the side wall part of the first storage part, and a wiring pattern formed on the top surface of the step part And a base on which the piezoelectric diaphragm is stored and the first storage part and a second storage part disposed on the top surface of the stepped part are formed, and a wiring pattern is formed on the front and back surfaces, A method of manufacturing a surface-mount piezoelectric oscillator having a plate-like circuit board in which front and back wiring patterns are electrically connected to each other, wherein the other main surface on which the wiring pads of the integrated circuit element are not formed is formed on the base. Dive on the bottom of the first storage Forming a metal bump on at least one of the wiring pattern of the integrated circuit element and the wiring pattern of the stepped portion of the base, or the wiring pattern on the back side of the circuit board, and the integrated circuit element The wiring pads on the back side of the circuit board are superposed on each other and ultrasonically joined to each other with the metal bumps interposed between the wiring pads of the step and the stepped portion of the base, thereby being electrically and mechanically joined to each other. And a step of bonding the lead electrode of the piezoelectric diaphragm to the wiring pattern on the upper surface side of the circuit board bonded to the integrated circuit element and the base with a conductive bonding material.

  By the above manufacturing method, the ultrasonic bonding tool is used from the upper part of the circuit board, and the integrated circuit element, the base, and the circuit board are simultaneously and extremely easily and efficiently electrically and ultrasonically bonded. can do. Since the piezoelectric vibration plate is bonded to the upper surface side of the circuit board to which these are bonded by the conductive bonding material, the piezoelectric vibration plate does not drop or tilt with respect to the first storage portion, and is in a more stable state. The piezoelectric diaphragm and circuit board can be joined.

  As described above, the present invention can provide a surface-mounted piezoelectric oscillator and a method for manufacturing the same that can be reduced in size and height while eliminating waste in the mounting area.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. An embodiment according to the present invention will be described with reference to the drawings by taking a surface-mounted crystal oscillator as an example. FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a plan view before a cover showing the embodiment of the present invention, FIG. 3 is a plan view of a circuit board showing the embodiment of the present invention, FIG. 4 is a bottom view of FIG. 3, and FIG. 5 is a schematic process diagram of the surface-mount crystal oscillator according to the embodiment of the present invention.

  The surface-mount type crystal oscillator is housed in a ceramic base 1 (insulating base) having a recess with an upper opening, an integrated circuit element 2 housed in the ceramic base, and the upper part in the ceramic base. A piezoelectric diaphragm 3, a circuit board 4 on which the piezoelectric diaphragm is mounted, and a lid 5 joined to the opening of the ceramic base.

  The ceramic base 1 is a rectangular parallelepiped as a whole, and is configured by appropriately laminating a ceramic such as alumina and a conductive material such as tungsten or molybdenum, and has a bank portion (side wall portion) 11 and a storage portion 10 on the upper surface side when viewed in cross section. The terminal electrode 14 is formed in a substantially concave shape on the bottom side. The storage unit 10 includes a first storage unit 10a and a second storage unit 10b, in which the integrated circuit element 2 and the piezoelectric diaphragm 3 are stored. A bank portion (side wall portion) 11 is formed around the storage portion, and the upper surface of the bank portion 11 is flat, and a circumferential sealing member 11a is formed on the bank portion. Examples of the sealing member include a member mainly composed of a metallized layer such as tungsten or molybdenum, and a member mainly composed of a metal ring such as kovar.

  Inside the ceramic base 1, the first storage portion 10a for storing the integrated circuit element 2 is formed on the inner bottom surface as described above, and the step portion 10c connected to the side wall portion of the first storage portion is formed. The piezoelectric diaphragm 3 to be described later is housed, and the first housing portion and the second housing portion 10b disposed on the upper surface of the stepped portion are formed.

  Wiring patterns 12a, 12b, 12c, and 12d are formed on the upper surface of the stepped portion 10c, and led to a terminal electrode 14 that is finally formed on the bottom surface of the ceramic base through casters and conductive vias (not shown). It is configured to be. The ceramic base having such a structure is formed using a known ceramic lamination technique or metallization technique, and each wiring pattern is formed with a nickel plating layer on the upper surface of the metallization layer made of tungsten, molybdenum, or the like, similar to the formation of the metal layer 11a. In this configuration, each gold plating layer is formed.

  The integrated circuit element 2 mounted in the first housing portion is a one-chip integrated circuit element that constitutes an oscillation circuit together with the piezoelectric diaphragm 3, and a plurality of wiring pads P are formed on the upper surface thereof. The integrated circuit element 2 is mechanically bonded to the inner bottom surface of the first storage portion of the base via, for example, a resin adhesive J on the bottom surface side where no wiring pad is formed.

  A circuit substrate 4 made of an epoxy resin substrate, an imide resin substrate, a ceramic substrate, a glass substrate, a quartz substrate, or the like is mounted above the integrated circuit element 2 with a predetermined interval. The circuit board 4 is set to have a thickness of, for example, 200 μm or less, and does not hinder a reduction in the height of the ceramic base 1. As shown in FIG. 3, the circuit board 4 has second wiring patterns 42a and 42b connected to a piezoelectric diaphragm 3 to be described later formed on the upper surface side, and the bottom surface side of the circuit board 4 has the above-mentioned structure on the bottom surface side as shown in FIG. For example, a plurality of six first wiring patterns 41a, 41b, 41c, 41d, 41e, and 41f connected to the integrated circuit element 2 are formed side by side. Among these, the second wiring pattern 42a is connected to the first wiring pattern 41c by a castellation or conductive via (not shown), and the second wiring pattern 42b is connected to the first wiring by a castellation or conductive via (not shown). It is connected to the pattern 41b.

  Then, the first wiring patterns 41a, 41b, 41c, 41d, 41e, and 41f of the circuit board 4 are mounted on the first storage portion corresponding to the positions of the first wiring patterns and the positions of the first wiring patterns. The plurality of wiring pads P on the upper surface of the integrated circuit element 2 are connected by FCB through metal bumps C (conductive bonding material) such as gold, and the wiring patterns 12a, 12b, 12c, 12d and the other end portions of the first wiring patterns 41a, 41d, 41e, and 41f of the circuit board 4 are connected by FCB via metal bumps C such as gold corresponding to the positions of these wiring patterns. The

  A piezoelectric diaphragm 3 is mounted above the circuit board 4 at a predetermined interval. The piezoelectric diaphragm 3 is, for example, a rectangular AT-cut quartz diaphragm, a pair of rectangular excitation electrodes 31 and 32 (32 is not shown) facing the front and back surfaces of the piezoelectric diaphragm 3 and the circuit board. Lead electrodes 33 and 34 are formed to be electrically connected to the second wiring patterns 42a and 42b formed on the upper surface side of the first and second wiring patterns 42a and 42b. Although not shown in the drawing, the lead electrodes 33 and 34 are formed around the front and back main surfaces of the piezoelectric diaphragm 3 so as to be mounted on either the front or back main surface of the piezoelectric diaphragm. Each of these electrodes is a laminated thin film composed of a base electrode layer such as chromium or nickel and an electrode layer mainly composed of silver or gold. Each of these electrodes can be formed by a thin film forming means such as a vacuum deposition method or a sputtering method.

  The piezoelectric diaphragm 3 and the circuit board 4 are joined using, for example, a silicone-based conductive resin adhesive S (conductive bonding material) that is in a paste form and contains metal fine pieces such as silver filler. With respect to the second wiring patterns 42a and 42b on the upper surface side of the circuit board 4 joined to the integrated circuit element 2 and the ceramic base 1, the extraction electrodes 33 and 34 of the piezoelectric diaphragm 3 are, for example, in the form of paste. Using a silicone-based conductive resin adhesive S (conductive bonding material) containing fine metal pieces such as a silver filler, they are electrically and mechanically bonded to each other, and cantilevered, for example, as shown in FIG. Has been. Note that the conductive bonding material is not limited to the silicone-based conductive resin adhesive shown in this embodiment, and other resin agents may be used. Further, a metal brazing material such as solder, a metal bump, or a metal plating bump may be used. .

  The lid 5 for hermetically sealing the ceramic base 1 has a configuration in which a sealing material such as a metal brazing material is formed on a core material made of, for example, Kovar. More specifically, for example, a nickel layer, a Kovar core material, The multilayer structure is an order of a copper layer and a silver brazing layer, and the silver brazing layer is joined to a ceramic-based metal layer. The external shape of the metal lid in plan view is substantially the same as or slightly smaller than that of the ceramic base.

  The ceramic base 1 in which the integrated circuit element 2, the circuit board 4, and the piezoelectric diaphragm 3 are stored in the storage unit 10 is covered with the metal lid 5, and the sealing material for the metal lid 5 and the sealing of the ceramic base are covered. The surface mounting type piezoelectric oscillator is completed by melt-curing the stopper member 11a and performing hermetic sealing. In the present embodiment, airtight sealing is performed by seam welding without using a metal ring for sealing, and the seam roller runs along the long side and short side ridges of the metal lid 5. Thus, the silver brazing (sealing material) formed on the metal lid 5 and the metal layer 11a (sealing member) of the ceramic base 1 are welded to perform hermetic sealing.

  Note that the integrated circuit element 2 mounted in the first storage portion is not only limited to the above embodiment, but is electrically and mechanically joined only by the circuit board 4 via the metal bumps C, as shown in FIG. In other words, the ceramic base may be configured not to be mechanically joined to the inner bottom surface of the first storage portion with a predetermined gap dimension interposed between the inner bottom surface of the first storage portion of the ceramic base. . In this configuration, the circuit board 4 in which only the integrated circuit element 2 is FCB-bonded in advance via the metal bump C can be easily obtained by FCB-bonding again to the step portion 10c of the ceramic base 1 via the metal bump C. .

  Next, an example of the manufacturing process of the surface mount crystal oscillator described above will be described with reference to FIG.

  In the step shown in FIG. 5A, the first storage portion 10a for storing the integrated circuit element 2, the step portion 10c connected to the side wall portion of the first storage portion, and the wiring on the top surface of the step portion. Ceramic base 1 in which patterns 12a, 12b, 12c, and 12d, the piezoelectric diaphragm 3 are accommodated, and the first accommodating portion and the second accommodating portion 10b disposed on the upper surface of the stepped portion are formed. Are preparing.

  In the step shown in FIG. 5B, the other main surface where the wiring pads of the integrated circuit element 2 are not formed is machined, for example, via a resin adhesive J with respect to the inner bottom surface of the first storage portion 10a of the base. Are bonded together (die bonding step).

  In the step shown in FIG. 5C, gold or the like is applied to the upper portions of the plurality of wiring pads P on the upper surface of the integrated circuit element 2 and the upper portions of the wiring patterns 12a, 12b, 12c, 12d of the stepped portion of the base. The metal bump C (conductive bonding material) is continuously formed from a bonding tool (capillary or the like) (not shown) by a bump bonder using a wire bonding technique such as thermocompression bonding. The metal bumps C may be formed only on the upper portions of the first wiring patterns 41a, 41b, 41c, 41d, 41e, and 41f of the circuit board 4 by the same method. Both metal bumps C are formed not only on P and the upper parts of the wiring patterns 12a, 12b, 12c and 12d but also on the upper parts of the first wiring patterns 41a, 41b, 41c, 41d, 41e and 41f by the same method. May be.

  In the step shown in FIG. 5D, the circuit board is formed with the metal bumps C interposed between the wiring pads P of the integrated circuit element 2 and the wiring patterns 12a, 12b, 12c, 12d of the stepped portion of the base. The first wiring patterns 41a, 41b, 41c, 41d, 41e, and 41f on the back surface side of 4 are superposed and the circuit board 4 is pressed onto the metal bumps C by a bonding tool (such as an ultrasonic welder) (not shown) to apply a static pressure. Apply. That is, by vibrating the bonding tool at a predetermined frequency, the bonding tool is connected to the integrated circuit element 2 and the circuit board 4 and the circuit board 4 and the ceramic base 1 through the metal bump C by the FCB (Flip Chip Bonding) method. Are ultrasonically bonded to each other and are electrically and mechanically bonded to each other.

  5E, the second wiring patterns 42a and 42b on the upper surface side of the circuit board 4 bonded to the integrated circuit element 2 and the ceramic base 1 and the extraction electrodes 33 and 34 of the piezoelectric diaphragm 3 are used. In between, a silicone-based conductive resin adhesive S (conductive bonding material) that is, for example, in the form of a paste and contains fine metal pieces such as a silver filler is interposed. Electromechanically joined.

  Thereafter, necessary processes such as a frequency adjustment process and an annealing process are performed, and airtight sealing is performed with the lid 5 to complete the surface-mount piezoelectric oscillator.

  The circuit board is not limited to the manufacturing method of the above embodiment, but only the integrated circuit element 2 is FCB bonded to the circuit board 4 via the metal bumps C in advance, and the metal bumps C are attached to the step portions 10c of the ceramic base. 4 and the ceramic base 1 are FCB bonded via the metal bumps C, and then the nozzle is inserted through the gap between the circuit board 4 and the ceramic base 1 so that the wiring board of the integrated circuit element 2 is not formed on the other main surface. For example, a resin adhesive J may be mechanically bonded to the inner bottom surface of the base first storage portion 10a. Further, the step of die bonding is omitted, and only the integrated circuit element 2 is FCB bonded to the circuit board 4 via the metal bumps C in advance, and then the metal bumps C are attached to the step portions 10c of the ceramic base, Only the circuit board 4 and the ceramic base 1 may be FCB bonded via the metal bumps C.

  According to the embodiment of the present invention, the plate-like circuit board 4 in which the piezoelectric diaphragm 3 and the integrated circuit element 2 are bonded to the front and back surfaces by the conductive resin adhesive S and the metal bumps C is formed on the step portion 10c of the ceramic base 1. Only by the metal bumps C, the electrical connection region between the piezoelectric diaphragm 3 and the ceramic base 1, the electrical connection region between the integrated circuit element 2 and the ceramic base 1, and the integration with the piezoelectric diaphragm 3. There is no need to separately form an electrical connection area with the circuit element 2 for the dam part (side wall part) 11, the step part 10c, and the storage part 10 of the ceramic base, and the ceramic base 1 can be reduced in size and height. Can respond to

  Further, the size and holding form of the piezoelectric diaphragm 3 that can be mounted according to the plane area of the first storage portion 10a and the plane area of the integrated circuit element 2 are not limited, and the piezoelectric diaphragm 3 used for the piezoelectric oscillator is not limited. The breadth of design is dramatically increased and there is no waste. In particular, even the piezoelectric diaphragm 3 smaller than the first housing part 10a can be easily mounted, and the circuit board 4 supports the piezoelectric diaphragm 3 and the piezoelectric diaphragm 3 is not tilted and mounted in the first housing part 10a. .

  Furthermore, the thermal adverse effect of the integrated circuit element 2 that generates heat during driving is transmitted to the piezoelectric diaphragm 3 in a more reduced state due to the interposition of the circuit board 4, and electrical characteristics such as frequency temperature characteristics are transmitted. There is little deterioration in characteristics.

  Further, the first wiring patterns 41a, 41b, 41c, 41d, 41e, 41f on the bottom surface side of the circuit board 4, the wiring pads P of the integrated circuit element 2, and the wiring patterns 12a on the upper surface of the stepped portion of the base. Since 12b, 12c, and 12d are joined only by the metal bump C, each joining area is space-saving and reliable electromechanical compared to the case of joining using a conductive resin adhesive or brazing material. Bonding can be performed, and no unnecessary gas is generated during bonding. As a result, the area of the stepped portion 10c can be further reduced, and not only can the size of the ceramic base 1 be further reduced, but also the electrical performance of the piezoelectric oscillator is not adversely affected, thereby improving the aging characteristics. Can do.

  Further, compared to a configuration in which the integrated circuit element 2 and the ceramic base 1 are connected using wire bonding, the gap is such that other members such as the piezoelectric diaphragm 3 and the circuit board 4 are not in direct contact with the upper part of the wire bonding. A space is not required, and the ceramic base 1 has a low profile and can be easily handled.

  Furthermore, in the present invention, since the circuit board 4 is joined to the upper portion of the ceramic base first storage portion 10a via the ceramic base step portion 10c and the integrated circuit element 2, the mechanical bending strength of the ceramic base 1 is increased. Can be increased. In particular, by increasing the bending strength of the ceramic base, it is possible to suppress cracks in the ceramic base that are likely to occur when hermetic sealing is performed by local heating such as seam sealing or beam sealing.

  Further, in the present embodiment, since the metal bump C is made of the same material made of gold or the like and has the same shape, the first wiring patterns 41a, 41b, 41c, 41d, 41e, 41f on the bottom surface side of the circuit board and the above-mentioned The bonding strength of the metal bumps C between the wiring pads P of the integrated circuit element 2 and the wiring patterns 12a, 12b, 12c, 12d on the upper surface of the stepped portion of the base can be made uniform. Moreover, since the bonding conditions are the same by using the metal bumps C of the same material, it is possible to apply ultrasonic waves from the upper part of the circuit board 4 and perform the FCB bonding at the same time, and there is no variation in strength at that time. .

  Further, according to the manufacturing method of the present embodiment, the integrated circuit element 2, the ceramic base 1, and the circuit board 4 can be extremely easily and efficiently simultaneously using an ultrasonic bonding tool from above the circuit board 4. In addition, ultrasonic bonding can be performed electrically and mechanically. Since the piezoelectric vibration plate 3 is bonded to the upper surface side of the circuit board 4 to which they are bonded by the conductive resin adhesive S, the piezoelectric vibration plate 3 does not drop or tilt with respect to the first storage portion 10a. Thus, the piezoelectric diaphragm 3 and the circuit board 4 can be joined in a more stable state.

  Another embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view showing another embodiment of the present invention. Since the basic configuration is the same as that of the above-described embodiment, the same reference numerals are used for the same components, and only differences will be described.

  The integrated circuit element 2 mounted in the first housing portion is mechanically bonded to the inner bottom surface of the first housing portion of the base via, for example, a resin adhesive J on the bottom surface side where no wiring pad is formed. Has been. A circuit board 4 is mounted above the integrated circuit element 2 with a predetermined interval. At this time, in the present modification, the first wiring patterns 41a, 41b, 41c, 41d, 41e, 41f of the circuit board 4 and the first storage portions corresponding to the positions of the first wiring patterns. This is the same as the above-described embodiment in that a plurality of wiring pads P on the upper surface of the integrated circuit element 2 mounted on is connected by FCB via metal bumps C (conductive bonding material) such as gold. However, the wiring patterns 12a, 12b, 12c, 12d on the upper surface of the stepped portion of the ceramic base 1 and the first wiring patterns 41a, 41d, 41e, 41f of the circuit board 4 corresponding to the positions of these wiring patterns, However, it is different in that it is electrically and mechanically bonded to each other using, for example, a silicone conductive resin adhesive S (conductive bonding material) that is in the form of a paste and contains fine metal pieces such as silver filler. ing. In addition, it is not limited to a silicone-based conductive resin adhesive, and other resin agents may be used, and a metal brazing material such as solder may be used. In this configuration, only the integrated circuit element 2 is FCB bonded to the circuit board 4 via the metal bumps C in advance, and the circuit board is bonded to the ceramic base step portion 10c coated with the conductive resin adhesive S with the resin. It can be easily obtained by mounting and bonding to the inner bottom surface of the ceramic-based first storage portion 10a coated with the agent J.

  According to the modification of the above embodiment, the variation in flatness of the step portion 10c on the ceramic base and the variation in the gap between the step portion 10c on the circuit board 4 and the ceramic base are absorbed in the joining region of the conductive resin adhesive S. More reliable electromechanical joining can be performed. In particular, when a flexible conductive resin adhesive such as a silicone type is used, the external impact on the piezoelectric diaphragm 2 can be reduced, so that the impact resistance performance is improved. In this modification, the conductive bonding material used for bonding the step portion of the ceramic base 1 and the circuit board 4 and the conductive bonding material used for bonding the piezoelectric diaphragm 3 and the circuit board 4 are made of the same material. The silicone type conductive resin adhesive is used. In this way, by using the same material for each conductive bonding material, the process conditions for bonding the conductive bonding material (curing temperature in the case of resin adhesive, melting in the case of brazing material) The temperature and the like can be made the same, which is a preferable form for manufacturing.

In each of the embodiments of the present invention described above, an AT cut quartz crystal diaphragm is used as the piezoelectric diaphragm, but the present invention is not limited to this, and a tuning fork type quartz diaphragm may be used. Further, although quartz is used as the piezoelectric diaphragm, the present invention is not limited to this, and a piezoelectric single crystal material such as piezoelectric ceramics or LiNbO ₃ may be used. That is, any piezoelectric diaphragm can be applied. Further, although the piezoelectric diaphragm is cantilevered on the upper part of the circuit board, the configuration may be such that both ends of the piezoelectric diaphragm are held. In addition, the sealing configuration in each embodiment of the present invention is not limited to seam sealing, but may be beam sealing (for example, laser beam or electron beam), glass sealing, brazing material sealing, or the like.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

Sectional drawing which shows embodiment of this invention. The top view before carrying out the lid | cover which shows embodiment of this invention. The top view of the circuit board which shows embodiment of this invention. FIG. 4 is a bottom view of FIG. 3. 1 is a schematic process diagram of a surface-mount crystal oscillator according to an embodiment of the present invention. Sectional drawing which shows the modification of embodiment of this invention. Sectional drawing which shows other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic base 2 Integrated circuit element 3 Piezoelectric diaphragm 4 Circuit board S Conductive resin adhesive C Metal bump

Claims (4)

A surface-mount piezoelectric oscillator having a piezoelectric diaphragm having an excitation electrode and an extraction electrode and an integrated circuit element having a wiring pad formed on one main surface, and having an insulating base for housing them.
The base has a side wall portion and a storage portion on the upper surface side, and a terminal electrode on the bottom surface side,
The storage portion includes a first storage portion in which the integrated circuit element is stored on an inner bottom surface;
A step portion connected to the side wall portion of the first storage portion;
The piezoelectric diaphragm is housed, and the first housing part and the second housing part disposed on the upper surface of the stepped part are formed,
The wiring pattern on the upper surface side of the plate-like circuit board on which the wiring pattern is formed on the front and back surfaces and the extraction electrode of the piezoelectric diaphragm are bonded with a conductive bonding material, and the wiring pattern on the bottom surface side of the circuit board and the integrated circuit The circuit element wiring pad is bonded with a conductive bonding material, and the piezoelectric diaphragm and the integrated circuit element are electrically connected to each other only by the circuit board.
The wiring pattern on the circuit board is led out to the terminal electrode of the base by bonding the wiring pattern on the top surface of the stepped portion and a part of the wiring pattern on the bottom surface side of the circuit board with a conductive bonding material. A surface-mounted piezoelectric oscillator characterized by The main surface on which the wiring pad of the integrated circuit element is not formed is mechanically bonded to the inner bottom surface of the first storage portion of the base, and the wiring pattern on the bottom surface side of the circuit board and the wiring pad of the integrated circuit element 2. The surface-mount piezoelectric oscillator according to claim 1, wherein the wiring pattern on the upper surface of the step portion of the base and the wiring pattern on the bottom surface side of the circuit board are joined by metal bumps. The main surface on which the wiring pad of the integrated circuit element is not formed is mechanically bonded to the inner bottom surface of the first storage portion of the base, and the wiring pattern on the bottom surface side of the circuit board and the wiring pad of the integrated circuit element The wiring pattern on the upper surface of the stepped portion of the base and the wiring pattern on the bottom surface side of the circuit board are bonded with a conductive resin adhesive or a metal brazing material. The surface-mount piezoelectric oscillator according to claim 1. A piezoelectric diaphragm in which an excitation electrode and an extraction electrode are formed;
An integrated circuit element having a wiring pad formed on one main surface;
A first storage portion that stores the integrated circuit element, a step portion connected to a side wall portion of the first storage portion, a wiring pattern formed on an upper surface of the step portion, and the piezoelectric diaphragm are stored. And a base on which the first storage portion and a second storage portion disposed on the upper surface of the stepped portion are formed,
A method of manufacturing a surface-mounted piezoelectric oscillator having a wiring pattern formed on the front and back surfaces and a plate-like circuit board in which the wiring patterns on the front and back surfaces are electrically connected to each other,
Die bonding the other main surface of the integrated circuit element where the wiring pads are not formed on the bottom surface of the first storage portion of the base;
Forming metal bumps on at least one of the wiring pattern of the integrated circuit element and the wiring pattern of the stepped portion of the base, or the wiring pattern on the back side of the circuit board;
The wiring patterns on the back side of the circuit board are superposed and ultrasonically bonded to each other with the metal bumps interposed between the wiring pads of the integrated circuit element and the wiring pads of the stepped portion of the base. Mechanically joining, and
A surface-mount type piezoelectric oscillator comprising a step of bonding a lead electrode of a piezoelectric diaphragm to a wiring pattern on an upper surface side of a circuit board bonded to the integrated circuit element and a base with a conductive bonding material Manufacturing method.

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