JP2008211428A - Piezoelectric oscillator - Google Patents

Abstract

A piezoelectric oscillator that can be formed by superimposing a piezoelectric vibrator and an integrated circuit chip, can be miniaturized, and is provided with an inspection terminal exposed to the outside so that a work with a contact pin can be easily performed. To provide.
An integrated circuit chip is disposed below a piezoelectric vibrator that houses a piezoelectric vibrating piece in an insulating package, and the piezoelectric oscillator includes the piezoelectric vibrating piece and the integrated circuit chip connected to each other. The inactive surface 41 of the integrated circuit chip faces outward, the active surface 41 side of the integrated circuit chip and the inactive surface 42 side are electrically connected by a through hole 47, and at least the inspection terminal 45 Is formed on the inactive surface side.
[Selection] Figure 1

Description

  The present invention relates to an improvement in a piezoelectric oscillator formed using a piezoelectric vibrator.

Piezoelectric oscillators are widely used in small information devices such as HDDs (hard disk drives), mobile computers, and IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems.
For example, a piezoelectric oscillator requires a piezoelectric vibrator and an integrated circuit chip that performs temperature compensation thereof.

For example, a piezoelectric vibrating piece is mounted on the surface side of a predetermined substrate, sealed with a cap to form a piezoelectric vibrator, and on the back surface of the substrate of the piezoelectric vibrator, an accommodation space is enclosed inside the periphery. A configuration in which an integrated circuit chip is formed and accommodated in the space is known (see Patent Document 1 and FIG. 1).
In such a configuration, there is an advantage that a small piezoelectric oscillator having a small mounting space can be obtained by packaging the piezoelectric vibrator and the integrated circuit chip in the vertical direction.

  In such a piezoelectric oscillator, the piezoelectric vibrator has a predetermined temperature-frequency characteristic. In other words, the frequency changes depending on the ambient environment temperature, but in order to have a flat characteristic in a relatively wide use environment temperature range including normal temperature in a use environment where this temperature-frequency characteristic is assumed, An inspection terminal which is a control terminal for inputting correction data or the like to the integrated circuit chip is required.

  In the piezoelectric oscillator of Patent Document 1, a pattern is routed from the electrode pad on the active surface on which the inspection terminal of the integrated circuit chip is formed to the inside of the package, extended to the side surface, and exposed to the side surface of the package. Contact pins are applied to enable inspection and data writing.

JP 2000-77943 A

  However, in recent years, the package has been very miniaturized and the overall thickness has been reduced, making it difficult to form inspection terminals on the side surfaces of the package.

  The present invention has been made to solve the above problems, and can be formed by superimposing a piezoelectric vibrator and an integrated circuit chip, which can reduce the size and expose the inspection terminal to the outside. It is an object of the present invention to provide a piezoelectric oscillator that is provided and is easy to work with a contact pin.

  According to the first aspect of the present invention, an integrated circuit chip is disposed below the piezoelectric vibrator in which the piezoelectric vibrating piece is housed in an insulating package, and the piezoelectric vibrating piece and the integrated circuit chip are arranged. A piezoelectric oscillator in which the inactive surface of the integrated circuit chip faces outward, the active surface side of the integrated circuit chip and the inactive surface side are electrically connected by a through hole, and at least a test terminal Is achieved by a piezoelectric oscillator formed on the inactive surface side.

According to the configuration of the first invention, since the integrated circuit chip is fixed to the lower side of the piezoelectric vibrator including the package, the horizontal size can be reduced, the mounting area can be reduced, and the size can be reduced. Can be measured.
In addition, the integrated circuit chip is mounted on the piezoelectric vibrator side using the electrode pad exposed on the active surface, while the electrode pad for the inspection terminal on the active surface is provided with a through hole in the integrated circuit chip. Since the inspection terminal is formed on the non-active surface that is formed and connected to the non-active surface side, the contact pin can be easily applied from the outside, and the handling becomes easy.
Further, since the inactive surface of the integrated circuit chip is directed to the outside, it is possible to prevent the sensitive active surface from being damaged.
Thus, the piezoelectric oscillator can be formed by overlapping the piezoelectric vibrator and the integrated circuit chip, and the piezoelectric oscillator can be reduced in size and provided with the inspection terminal exposed to the outside so that the work with the contact pin is easy. Can be provided.

According to a second invention, in the configuration of the first invention, a relocation wiring layer electrically connected to the active surface side is formed on the non-active surface, and an inspection terminal is utilized by using the relocation wiring layer. Is formed.
According to the configuration of the second aspect of the invention, by providing the rearrangement wiring layer on the non-active surface, it is possible not only to form the inspection terminal but also to arrange the rearrangement wiring layer to a predetermined position on the non-active surface. Since it can be routed freely, it is particularly easy to apply contact pins, or close to the mounting terminals of the piezoelectric oscillator, etc., avoiding places where electrical shorts are likely to occur, etc. It becomes possible to do.

According to a third aspect of the present invention, in the configuration of the first or second aspect, a metal ball is disposed on the lower surface of the piezoelectric vibrator to form a space, and the integrated circuit chip is accommodated in the space. It is characterized by that.
According to the configuration of the third invention, by using the metal ball on the lower surface of the piezoelectric vibrator, it is possible not only to obtain an accommodation space for the integrated circuit chip, but also from the mounting substrate side through the metal ball. Connections can be made. For this reason, there are advantages in that the manufacturing cost is low and the configuration is simple as compared with the case where a substrate is disposed below the piezoelectric vibrator for mounting an integrated circuit chip or obtaining the accommodation space.

According to a fourth invention, in the configuration of the first invention, a substrate is disposed below the piezoelectric vibrator, a space is formed between the piezoelectric vibrator and the substrate, and the integrated circuit chip is formed on the substrate. The integrated circuit chip is accommodated in the space, and a through hole is formed in the substrate to expose the inspection terminal formed in the integrated circuit chip.
According to the configuration of the fourth aspect of the invention, since the substrate is arranged below the piezoelectric vibrator, a stronger structure can be obtained. In addition, by forming a through hole in this substrate, the inspection terminal can be exposed to the outside, so that operation with a contact pin is possible.

According to a fifth invention, in the configuration of the fourth invention, the piezoelectric vibrator and the substrate are flip-chip connected.
According to the configuration of the fifth aspect of the present invention, not only can the accommodation space of the integrated circuit chip be obtained by using the metal ball so as to be flip-chip connected, but also from the mounting substrate side via the metal ball. Since electrical connection can be made, it is easier to obtain a lower cavity of the piezoelectric vibrator than to form a package.

According to a sixth aspect of the present invention, in the configuration of the fourth or fifth aspect, the integrated circuit chip is mounted on the substrate by mounting the active surface on the substrate with the active surface of the integrated circuit chip facing outward. The relocation wiring layer is formed on the active surface, and the inspection terminal formed by the relocation wiring layer is exposed from the through hole formed in the substrate.
According to the configuration of the sixth aspect of the invention, even if the active surface of the integrated circuit chip faces outward, it can be protected because it is covered by the substrate, and the relocation wiring layer is formed on the active surface. Inspection terminals can be formed at any location on the active surface.

1 and 2 show a first embodiment of a piezoelectric oscillator according to the present invention. FIG. 1 is a schematic sectional view thereof, and FIG. 2 is a schematic bottom view thereof.
As shown in FIG. 1, the piezoelectric oscillator 30 has an integrated circuit chip 40 disposed below the piezoelectric vibrator 10.
First, the piezoelectric vibrator 10 will be described.
The piezoelectric vibrator 10 is formed by housing a piezoelectric vibrating piece 13 in an insulating package 11 and sealing it with a lid 12. The package 11 is formed, for example, using an aluminum oxide ceramic green sheet as an insulating material so that the accommodation space S1 is provided inside.
That is, the package 11 is obtained by overlapping the first substrate 14 and the second substrate 15 and joining the lid 12 with the seam ring 16. In this case, the accommodation space S1 is formed by molding the second substrate 15 so as to remove the inner material before sintering. That is, the package 11 is formed by laminating a plurality of substrates made of green sheets and then sintering.

That is, in this embodiment, the package 11 is formed to be, for example, a rectangular box, and the internal space S <b> 1 is an accommodation space for accommodating the piezoelectric vibrating piece 13. An electrode part 23 is formed on a ceramic substrate constituting the bottom of the package 11, for example, a conductive adhesive 28 is applied, and the vicinity of the base end of the piezoelectric vibrating piece 13 is placed thereon and heated. Thus, the conductive adhesive 28 is cured and bonded.
Here, in this embodiment, a box-shaped package is formed to accommodate the piezoelectric vibrating piece 13. For example, a single ceramic substrate is prepared as an insulating base, An electrode portion is formed on the substrate, the piezoelectric vibrating piece 13 is bonded, and a thin box-shaped lid or lid is covered and sealed to form a package for accommodating the piezoelectric vibrating piece 13 as a whole. You may do it.

The first substrate 14 that is exposed to the internal space S1 and forms the inner bottom portion in the vicinity of the left end in the figure in the internal space S1 of the package 11 is formed by, for example, nickel plating and gold plating on tungsten metallization. The electrode part 23 is provided. Actually, one pair is provided at each end in the width direction of the package 11.
The electrode portion 23 is connected to a mounting terminal 25 as a connection terminal portion exposed to the outside on the bottom surface of the package 11 by a conductive through hole 24 provided in the package 11. This is supplied to the piezoelectric vibrating piece 13.

  The piezoelectric vibrating piece 13 is formed of, for example, quartz, and a piezoelectric material such as lithium tantalate or lithium niobate can be used in addition to quartz. In the case of this embodiment, the piezoelectric vibrating piece 13 may be, for example, a quartz vibrating piece formed by cutting a crystal into a rectangle or a tuning-fork type quartz vibrating piece.

For the mounting terminals 25 on the bottom surface of the first substrate 14 of the piezoelectric vibrator 10, that is, the bottom surface of the piezoelectric vibrator 10 itself, the integrated circuit chip 40 is utilized by using metal bumps (for example, gold bumps) 43. Is flip-chip mounted. The integrated circuit chip is a semiconductor chip, and particularly includes a temperature compensation circuit for a piezoelectric vibrator.
In particular, the surface 41 of the integrated circuit chip 40 is an active surface where the electrode pads 44a including the control terminals 44b (inspection terminals) of the integrated circuit chip 40 are exposed. The electrode pad portion of the active surface 41 is connected to the mounting terminal 25 of the piezoelectric vibrator 10 by the metal bump 43, and the inactive surface 42 of the integrated circuit chip 40 is exposed outward (downward). Has been.

That is, the third substrate 26 made of the same material as that constituting the package 11 is overlapped along the peripheral edge of the lower surface of the first substrate 14, and the accommodation space S <b> 2 is formed on the inner side. Package 27 is provided. In this accommodation space S2, the integrated circuit chip 40 is accommodated as shown in the figure.
For this reason, preferably, the height dimension of the third substrate 26 is set to be larger than the thickness dimension of the integrated circuit chip 40, whereby the accommodated integrated circuit chip 40 protrudes from the accommodation space S2 and is damaged. It is designed not to cause any of the above.
The mounting terminals 31, 31, 31, 31 shown in FIG. 2 are formed at the four corners on the lower surface of the third substrate. These mounting terminals are connected to the mounting terminals 25 of the piezoelectric vibrator 10 by conductive patterns that route the inner surface of the third substrate 26 and the like.

In the integrated circuit chip 40, through holes (conductive through holes) 47 filled with a conductive material are formed, and electrode pads 46 exposed to the non-active surface 42 and inspection terminals 45 are formed as shown in FIG. .
Here, a through hole 47 that penetrates the integrated circuit chip 40 and is electrically connected to the front and back is formed as follows.
For example, the through hole is formed by dry etching the silicon material of the integrated circuit chip 40 from the inactive surface 42 side corresponding to the back surface of the conductive pad 44b. Next, a conductive metal or the like is formed on the inner surface of the through hole by sputtering or the like, leaving the conductive pad 44b on the active surface 41. Thereafter, the through hole is filled with copper (Cu), and an electrode pad is formed on the inactive surface 42. Furthermore, by providing a conductive pattern integrally with the conductive pad, a rearranged wiring layer can be formed, and the conductive pad can be routed to an arbitrary location.
Further, the sealing resin 48 is resin-molded in the gap in the accommodation space S2 of the package 27.

The present embodiment is configured as described above. Since the integrated circuit chip 40 is fixed to the bottom surface of the first substrate 14 as the bottom plate below the piezoelectric vibrator 10, the size in the horizontal direction is set. Can be reduced, the mounting area can be reduced, and the size can be reduced.
In addition, the integrated circuit chip 40 is mounted on the piezoelectric vibrator 10 side using the electrode pads 44a exposed on the active surface 41, while the test terminal electrode pads 44b on the active surface 41 are integrated with the integrated circuit chip 40. Since the through-hole 47 is formed in the circuit chip 40 and connected to the inactive surface 42 side, and the inspection terminal 45 is formed on the inactive surface 42 facing outward, it is easy to apply a contact pin to the inspection terminal 45 from the outside, Handling becomes easy.
Further, since the inactive surface 42 of the integrated circuit chip 40 is directed to the outside, it is possible to prevent the sensitive active surface from being damaged.
Thus, the piezoelectric vibrator 10 and the integrated circuit chip 40 can be formed in an overlapped manner, so that the size can be reduced and the inspection terminal 45 is exposed to the outside so that the work with the contact pin is facilitated. A piezoelectric oscillator 30 can be provided.

FIG. 3 and FIG. 4 are diagrams showing a second embodiment of the piezoelectric oscillator, and in this embodiment, the portions denoted by the same reference numerals as those of the piezoelectric oscillator of FIG. 1 and FIG. The description which overlaps is abbreviate | omitted and demonstrates below centering on difference.
This embodiment is different from the embodiment of FIGS. 1 and 2 only in that a rearrangement wiring layer 49 is formed.
That is, as shown in FIGS. 3 and 4, the rearrangement wiring layer 49 is formed on the non-active surface 42 of the integrated circuit chip 40. The rearrangement wiring layer 49 forms a conductive pattern extending from the electrode pad 44b on the surface of the silicon substrate constituting the integrated circuit chip 40. In particular, the periphery of the electrode pad 44b is made of polyimide resin or the like. Insulation can be formed by drawing a copper pattern or the like on the surface.

When the rearrangement wiring layer 49 is formed as shown in the figure, the surface of the inactive surface of the integrated circuit chip 40 is further routed from the position of the conductive through hole 47 to the center of the chip, and the inspection terminal 45 is formed at that position. Like to do.
Thereby, compared with the embodiment of FIG. 2, the position of the inspection terminal 45 is set at a position further away from the mounting terminal 31 and the like.
Thereby, a short circuit can be prevented more reliably and the work of bringing the contact pins into contact with each other becomes easier.
The piezoelectric oscillator 30-1 of the second embodiment can exhibit the same functions and effects as those of the first embodiment except for such functions.
Of course, the inspection terminal 45 can be formed at any position other than the central portion of the integrated circuit chip 40 by using the rearrangement wiring layer 49 described above.

FIGS. 5 and 6 are diagrams showing a third embodiment of the piezoelectric oscillator, and in this embodiment, the portions denoted by the same reference numerals as those of the piezoelectric oscillator of FIGS. 1 and 2 have a common configuration. The description which overlaps is abbreviate | omitted and demonstrates below centering on difference.
In the piezoelectric oscillator 30-2, for example, a rectangular fourth substrate 33 is connected to the mounting terminal 25 of the piezoelectric vibrator 10 using a conductive metal ball 35. The fourth substrate 33 is formed of, for example, a relatively flexible polyimide substrate, a hard glass epoxy substrate, a ceramic substrate, or the like.

Electrode portions 36 are formed at the four corners of the upper surface of the fourth substrate 33, and are wound around the front side so as to be integrated with the mounting terminals 31.
The metal ball is, for example, an Au ball, which is melted between the mounting terminal 25 of the piezoelectric vibrator 10 and the electrode 36 of the fourth substrate 33 and bonded thereto.

In the integrated circuit chip 40, the inactive surface 42 is bonded and fixed to the surface of the fourth substrate 33 with an adhesive or the like with the active surface 41 facing the piezoelectric vibrator 10 side. The electrode pads 44 a and 44 b on the active surface 41 of the integrated circuit chip 40 and the electrode 36 on the fourth substrate 33 are connected by bonding with a bonding wire 37.
A through hole 34 is formed at the center of the fourth substrate 33, and the inspection terminal 45 is exposed from the through hole 34 as shown in FIG. 6.
The accommodation space S2 between the piezoelectric vibrator 10 and the fourth substrate 33 is filled with a mold resin (not shown) to form a package 27-1.

Since the present embodiment is configured as described above, the same effects as those of the first embodiment are exhibited, and the fourth substrate 33 is used, so that the strength is improved.
Further, since the metal ball 35 is used for joining the piezoelectric vibrator 10 and the fourth substrate 33, there are various advantages such as being able to perform electrical joining and mechanical joining at the same time and being compact.

FIGS. 7 and 8 are diagrams showing a fourth embodiment of the piezoelectric oscillator. In this embodiment, the portions denoted by the same reference numerals as those of the piezoelectric oscillators of FIGS. 1 and 2 have a common configuration. The description which overlaps is abbreviate | omitted and demonstrates below centering on difference.
The piezoelectric oscillator 30-3 is different from the third embodiment in that a package 27-2 in which a third substrate 26 is stacked on a fourth substrate 33 is used.
That is, a box-shaped package 27-2 that accommodates the integrated circuit chip 40 is formed by using the third substrate 26 instead of the metal ball to join the piezoelectric vibrator 10 and the fourth substrate 33. ing. Then, the piezoelectric vibrator 10 and the fourth substrate 33 are electrically connected by drawing a conductor such as tungsten metallization and plating inside the package 27-2.

The active surface 41 of the integrated circuit chip 40 is opposed to the electrode 36 formed on the surface of the fourth substrate 33, and metal balls 43 and 43 are interposed between the electrode pads 44a and 44b, and flipping is performed. Chip connected.
For example, a rectangular fourth substrate 33 is connected to the mounting terminal 25 of the piezoelectric vibrator 10 using a conductive metal ball 35. The fourth substrate 33 is formed of, for example, a relatively flexible polyimide substrate, a hard glass epoxy substrate, a ceramic substrate, or the like.
Further, the active surface 41 of the integrated circuit chip 40 is directed outward, a rearrangement wiring layer 49 is formed on the active surface, an inspection terminal 45 is formed in the center of the integrated circuit chip 40, and the inspection terminal 45 Is exposed to the outside through the through hole 34. Since the active surface 41 of the integrated circuit chip 40 is directed downward, no conductive through hole is formed in the chip itself.

The present embodiment is configured as described above, and exhibits substantially the same function and effect as the piezoelectric oscillator 30-2 of the third embodiment. However, the package 27-2 has a configuration in which a ceramic package is further provided below the piezoelectric oscillator 10, and is robust, but is slightly inferior in terms of manufacturing cost.
Further, since the integrated circuit chip 40 is flip-chip connected to the fourth substrate 33 with the active surface facing downward, there is an advantage that it is not necessary to perform wire bonding as in the third embodiment.

FIG. 9 and FIG. 10 are diagrams showing a fifth embodiment of the piezoelectric oscillator, and in this embodiment, the portions denoted by the same reference numerals as those of the piezoelectric oscillator of FIG. 1 and FIG. The description which overlaps is abbreviate | omitted and demonstrates below centering on difference.
This piezoelectric oscillator 30-4 is different from the second embodiment only in that the metal ball 35 is used without using the third substrate 26.

That is, in the piezoelectric oscillator 30-4 of this embodiment, a metal ball 35 having a relatively large diameter is disposed on each mounting terminal 25 of the piezoelectric vibrator 10. In addition to exhibiting the function, it functions as a spacer for creating the accommodation space S2 of the integrated circuit chip 40.
In addition, although not shown in figure, the location of accommodation space S2 is filled with mold resin.
The diameter of the metal ball 35 is made larger than the thickness of the integrated circuit chip 40, so that the integrated circuit chip 40 is completely accommodated in the accommodation space S2, and at the four corners on the lower surface of the piezoelectric oscillator 30-4. The lower part of the metal ball 35 is exposed and functions as a mounting terminal. Other functions and effects are the same as those of the second embodiment.

The present invention is not limited to the above-described embodiment. Each configuration of each embodiment can be appropriately combined or omitted, and can be combined with other configurations not shown.
Further, the shape of the package of the piezoelectric vibrator 10 is not limited to the illustrated one, and various forms can be applied.

1 is a schematic cross-sectional view showing a first embodiment of a piezoelectric oscillator of the present invention. The schematic bottom view of the piezoelectric oscillator of FIG. The schematic sectional drawing which shows 2nd Embodiment of the piezoelectric oscillator of this invention. FIG. 4 is a schematic bottom view of the piezoelectric oscillator of FIG. 3. The schematic sectional drawing which shows 3rd Embodiment of the piezoelectric oscillator of this invention. FIG. 6 is a schematic bottom view of the piezoelectric oscillator of FIG. 5. The schematic sectional drawing which shows 4th Embodiment of the piezoelectric oscillator of this invention. The schematic bottom view of the piezoelectric oscillator of FIG. FIG. 9 is a schematic cross-sectional view showing a fifth embodiment of the piezoelectric oscillator of the present invention. FIG. 10 is a schematic bottom view of the piezoelectric oscillator of FIG. 9.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Piezoelectric vibrator, 11 ... Package, 13 ... Piezoelectric vibrating piece, 24 ... Through hole, 30 ... Piezo oscillator, 33 ... Substrate, 40 ... Integrated circuit chip, 41 ... active surface, 42 ... inactive surface, 45 ... inspection terminal, 49 ... relocation wiring layer

Claims (6)

A piezoelectric oscillator in which an integrated circuit chip is arranged on the lower side of a piezoelectric vibrator that houses a piezoelectric vibrating piece in an insulating package, and the piezoelectric vibrating piece and the integrated circuit chip are connected,
The inactive surface of the integrated circuit chip faces outward, the active surface side of the integrated circuit chip and the inactive surface side are electrically connected by a through hole, and at least an inspection terminal is formed on the inactive surface side. A piezoelectric oscillator characterized by that.   The relocation wiring layer electrically connected to the active surface side is formed on the non-active surface, and an inspection terminal is formed using the relocation wiring layer. Piezoelectric oscillator.   3. The piezoelectric oscillator according to claim 1, wherein a metal ball is disposed on a lower surface of the piezoelectric vibrator to form a space, and the integrated circuit chip is accommodated in the space. .   A substrate is disposed below the piezoelectric vibrator, a space is formed between the piezoelectric vibrator and the substrate, the integrated circuit chip is fixed to the substrate, and the integrated circuit chip is accommodated in the space. The piezoelectric oscillator according to claim 1, wherein a through hole is formed in the substrate to expose the inspection terminal formed in the integrated circuit chip.   The piezoelectric oscillator according to claim 4, wherein the piezoelectric vibrator and the substrate are flip-chip connected.   The integrated circuit chip is fixed to the substrate by mounting the active surface on the substrate with the active surface of the integrated circuit chip facing outward, and a relocation wiring layer is formed on the active surface. 6. The piezoelectric oscillator according to claim 4, wherein an inspection terminal formed of the rearranged wiring layer is exposed from a through hole formed in the substrate.

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