JPH11112268A - Piezoelectric device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize and thin a device and to reduce cost by arranging a piezoelectric oscillator in a groove part held by mounting faces where a semiconductor integrated circuit is flip chip-bonded. SOLUTION: An electrode pattern 3 for connecting it to a semiconductor integrated circuit for real time clock (IC chip) 2 is metallized by a base 1 formed by the insulated substrate of stack ceramic with a metal wiring material by printing. Metallic bumps 4 are formed on the electrode pads of an IC chip 2 and they are connected with the electrode patterns 3 formed on the base 1 by flip chip bonding technology. A tuning fork-type crystal oscillator 6 has two micro opening parts 8 provided for the supporting part 7. The opening parts 8 and the bumps 4 provided for the electrode pads 9a and 9b for crystal oscillator connection of the IC chip 2 are connected and fixed by conductive adhesive 5. Thus, the crystal oscillator 6 is stored in the groove part 11 of the base 1 by mounting the IC chip 2 so that it is connected to the respective electrode patterns 3 formed on the surface 10 of the base 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric device having a semiconductor integrated circuit and a piezoelectric vibrator built in a package, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, devices such as HDDs (hard disk drives), mobile computers, and small information devices such as IC cards, and mobile communication devices such as mobile phones and car phones have been remarkably reduced in size and thickness. Piezoelectric devices such as a piezoelectric oscillator and a real-time clock module are also required to be small and thin. At the same time, there is a need for a surface mount type device that can be mounted on both sides of a circuit board of an apparatus.

Therefore, an example of a conventional piezoelectric device will be described using a real-time clock module shown in the structural diagrams of FIGS. 6A and 6B using a quartz oscillator as a piezoelectric oscillator.

In the configuration of the conventional real-time clock module shown in FIGS. 6A and 6B, an IC chip 101 for a real-time clock having an oscillation circuit is electrically connected to an island portion 103 which is a part of a lead frame 102. It is bonded and fixed with an adhesive or the like, and is electrically connected to the input / output lead terminals 105 arranged on the outer peripheral portion of the package by Au wire bonding wires 104. A clock-type crystal oscillator 106 oscillating at a frequency of 32.768 kHz of a cylinder type is electrically connected to and fixed to the connection pads of the lead frame 102. Here, as shown in FIG. 6B, the cylinder-type quartz oscillator 106 is disposed on the opposite side of the IC chip 101 through the island portion 103.

The above-described IC chip 101, lead frame 102, and crystal oscillator 106 are integrally formed by resin molding.

[0006]

The conventional real-time clock module described above has a stacked type structure in which an IC chip and a crystal unit are stacked with emphasis on making the bottom area of the package as small as possible. ing. However, the diameter of the cylinder type crystal unit is about φ
1.5mm ~ φ2mm large, this crystal oscillator and IC
The thickness of the chip determines the thickness of the package of the real-time clock module, and it is very difficult to reduce the thickness.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a small-sized piezoelectric device having a thickness of 1 mm or less at a low cost.

[0008]

According to the first aspect of the present invention,
In a piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are built in a package, the semiconductor integrated circuit is mounted on a base made of ceramic by flip-chip bonding, and formed on a bump formed on the semiconductor integrated circuit and on the base. The electrode pattern is electrically connected, and the piezoelectric vibrator is disposed between the base and the semiconductor integrated circuit, and is electrically connected to the piezoelectric vibrator connection bump formed on the semiconductor integrated circuit. It is characterized by having been done.

According to a second aspect of the present invention, in the first aspect, the semiconductor integrated circuit is mounted on a base formed of ceramic by flip-chip bonding, and the base is sandwiched between mounting surfaces on which the semiconductor integrated circuit is flip-chip bonded. And a piezoelectric vibrator is disposed in the groove.

According to a third aspect of the present invention, in the first aspect, the piezoelectric vibrator has an opening at a connection portion with a bump for connecting the piezoelectric vibrator formed on the semiconductor integrated circuit. I do.

According to a fourth aspect of the present invention, in the first aspect, the semiconductor integrated circuit has an electrode pad for connecting an electrode pattern formed on a base on a side opposite to the semiconductor integrated circuit. It has an electrode pad for connection of the piezoelectric vibrator.

According to a fifth aspect of the present invention, in the first aspect, the electrode pattern formed on the peripheral portion on the base made of ceramic is metallized with at least two metal layers. .

According to a sixth aspect of the present invention, in the first aspect, the bump formed on the semiconductor integrated circuit is a bump formed by Au wire bonding.

According to a seventh aspect of the present invention, in the first aspect, the piezoelectric vibrator is a quartz vibrator.

According to an eighth aspect of the present invention, in the first aspect, the semiconductor integrated circuit is a real-time clock IC.

According to a ninth aspect of the present invention, there is provided a step of forming a bump on each pad of a semiconductor integrated circuit, and a step of mounting and connecting a piezoelectric vibrator to a bump for connecting a piezoelectric vibrator formed on the semiconductor integrated circuit. A step of connecting and fixing the semiconductor integrated circuit to a predetermined position of the base by flip chip bonding, a step of mounting and sealing a lid (lid) on the base, and a step of using an opening provided in the base or the lid. A step of laser-processing a predetermined position of the piezoelectric vibrator to adjust the frequency, and a step of vacuum-sealing the opening in a vacuum atmosphere.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of the piezoelectric device of the present invention uses a real-time clock semiconductor integrated circuit as a semiconductor integrated circuit and a timepiece 32.768 as a piezoelectric vibrator.
An example of a real-time clock module using a KHz crystal oscillator will be described with reference to the drawings.

(Embodiment 1) FIG.
FIG. 10 is a structural diagram of a surface mount type real-time clock module according to the inventions described in 4, 5, 6, 7, 8 and 9.

As shown in the plan view of FIG. 1A and the front view of FIG. 1B, a semiconductor integrated circuit for real-time clock (IC chip: An electrode pattern 3 for connecting to a chip 2) is metallized by printing with a metal wiring material such as W (tungsten) or Mo (molybdenum). Then, Ni plating, Au plating or the like is applied thereon.

The electrode pads of the IC chip 2 have Au
Electrode pattern 3 formed on the base 1 by a flip chip bonding method.
Is connected to There are various processing methods for the flip chip bonding method, and the method used in this embodiment is a processing method using the conductive adhesive 5. Further, the reliability of the connection is increased by using an underfill material.

As shown in FIG. 2, the tuning-fork type quartz vibrator 6 has two small openings 8 provided in a support portion 7 thereof.
The opening 8 and the bumps 4 provided on the electrode pads 9 a and 9 b for connecting the crystal oscillator of the IC chip 2 are connected and fixed by the conductive adhesive 5. Here, the electrode pads 9a and 9b are about 2% of other electrode pads of the IC chip 2.
It is designed to have double to quadruple space.
This is to ensure sufficient mount connection strength of the crystal unit 6 and to reduce the contact resistance of the mount.

Then, the crystal oscillator 6 is connected to the I
The C chip 2 is mounted so as to be connected to each of the electrode patterns 3 formed on the surface 10 of the base 1. Therefore, the crystal resonator 6 has a structure in which it is housed in the groove 11 of the base 1.

Further, a metal lid (lid) 12 is positioned and fixed to the base 1, and a metal brazing material 13 such as solder is used.
Is melted and sealed. In this embodiment, the lid 12 has a surface on which solder is clad in advance.
As shown in (b), it is drawn into a box shape by a forming die or the like.

The lid 12 has a circular opening 14.
The opening 14 is used to trim a part of the metal electrode portion of the tuning-fork type quartz vibrator 6 by a laser device or an electron beam device to adjust the frequency.

Then, a small metal piece 15 for sealing is mounted on the opening 14 and vacuum sealing is performed using a sealant 16 in a vacuum atmosphere. Here, Au is used as the sealant 16.
-Sn, solder, or the like is used.

As described above, the real-time clock module 17 of a small and thin surface mount package is completed.

FIG. 3 is a structural diagram of the base 1 of the real-time clock module 17 of the present invention. The base 1 formed of the laminated ceramic has a drawback in that a sintering process causes a convex warpage as shown in FIG. 3 because ceramic sheets having different shapes are bonded to each other. (This warp is exaggerated in FIG. 3.) The amount of this warp is generally several tens of μm (about 20 to 50 μm) although it depends on the structure of the base 1.

In such a warped state, the height of the electrode pattern 31 arranged at the center of the base 1 and the height of the electrode pattern 32 arranged at the periphery of the base 1 vary, and the flip occurs. An electrode pattern 32 disposed particularly at the periphery of the base 1 during chip bonding;
A connection failure (open failure) with the bump 4 formed on the C chip 2 occurs.

Therefore, in the present invention, as shown in FIG. 3, at least two metallized layers of the electrode pattern 32 disposed on the peripheral portion of the base 1 are formed, and the thickness thereof is smaller than that of the central electrode pattern 31. It is formed to be 30 μm thick. As a result, the height of the electrode pattern 31 arranged at the center of the base 1 and the height of the electrode pattern 32 arranged at the periphery of the base 1 become the same, and reliable bonding can be performed.

FIG. 4 is a block diagram showing a manufacturing process of the real-time clock module 17 of the present invention.
Hereinafter, the manufacturing process will be described in detail with reference to this block diagram.

In the bump forming step of forming the bumps 4 on each pad of the IC chip 2, a plurality of IC chips 2 are set, and the Al electrode of the IC chip 2 is formed by a wire bonding type bump forming apparatus using Au wire lines. This is a step of forming bumps 4 having a height of several tens of μm on the pad surface.

Next, in the mounting step of mounting the crystal unit 6 on the IC chip 2, the fine opening provided in the crystal unit 6 is formed on the bump 4 for connecting the crystal unit provided on the IC chip 2. 8 is a step of positioning and connecting and fixing with a conductive adhesive 5 or the like.

Next, an FCB (flip chip bonding) step of connecting and fixing the IC chip 2 to which the crystal unit 6 is connected at a predetermined position on the base 1 by flip chip bonding is performed at the tip of the bump 4. A conductive adhesive 5 is applied, the IC chip 2 is heated under pressure to electrically connect the electrode pattern 3 provided on the base 1 to the bumps 4, and then an underfill material is injected into the IC chip. This is a step of fixing the second.

In the next step, the metal lid 12 is positioned and fixed to the base 1, and the metal brazing material 13 such as solder is used.
This is a first sealing step of melting and sealing.

Next, a frequency adjusting step of adjusting the frequency by laser processing a predetermined position of the piezoelectric vibrator 6 is performed.

Then, a second sealing step of mounting a small metal piece 15 for sealing in the opening 14 and performing vacuum sealing using a sealing agent 16 in a vacuum atmosphere is performed.

Further, the surface of the lid 12 is marked by a laser device or the like, and the real-time clock module 17 is completed.

The above is the manufacturing process of the real-time clock module of the present invention.

(Embodiment 2) FIG. 5 shows another embodiment of the present invention, in which an opening 41 for frequency adjustment is formed in a base 42. FIG. In the second embodiment, the lid 43 has a flat plate shape.

The present invention is not limited to the above embodiments, and the components can be freely combined.

As described above, a small and thin real-time clock module having a width of 4.7 mm, a width of 3.2 mm and a thickness of 0.8 mm can be obtained at low cost by using highly reliable and inexpensive components such as ceramics and metals. .

Here, the size of the conventional mold type real-time clock module is 10 mm in width, 7.5 mm in width, and 3.2 mm in thickness. In comparison with this, the real-time clock module of the present invention has a volume ratio of about 1 mm. / 20, which is very small and thin.

[0043]

According to the first, second, sixth, seventh, eighth, and ninth aspects of the present invention, the semiconductor integrated circuit is mounted on a base formed of ceramic by flip chip bonding, and the base is formed by flipping the semiconductor integrated circuit. By having a groove sandwiched between the mounting surfaces to be chip-bonded, and arranging the piezoelectric vibrator in the groove, the thickness of the piezoelectric device can be reduced to 1 mm or less. It has the effect that it can be provided.

According to the third and fourth aspects of the present invention, the piezoelectric vibrator can be directly mounted on the semiconductor integrated circuit by forming an opening for bump connection in the piezoelectric vibrator. An electrode portion for a piezoelectric vibrator formed on the base or the like becomes unnecessary, and a piezoelectric device can be provided at low cost. Further, such a structure has an effect that the thickness can be further reduced.

According to the fifth aspect of the present invention, the metallization layer of the electrode pattern 32 disposed on the peripheral portion of the base 1 is formed as two layers, and the thickness thereof is formed to be large, thereby eliminating the height variation, and eliminating the electrode pattern. This has the effect of eliminating poor connection with bumps and obtaining a highly reliable piezoelectric device with good manufacturing yield.

[Brief description of the drawings]

FIG. 1 is a structural view of a piezoelectric device of the present invention. (A) is a top view. (B) is a front view.

FIG. 2 is an enlarged view of an IC chip portion of the piezoelectric device of the present invention.

FIG. 3 is an enlarged view of a base of the piezoelectric device of the present invention.

FIG. 4 is a block diagram showing a manufacturing process of the piezoelectric device of the present invention.

FIG. 5 is a structural view of another embodiment of the present invention. (A) is a top view. (B) is a front view.

FIG. 6 is a structural view of a conventional piezoelectric device. (A) is a top view. (B) is a front view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 IC chip 3 Electrode pattern 4 Bump 5 Conductive adhesive 6 Crystal vibrator 7 Supporting part 8 Opening 9a, 9b Electrode pad 10 Surface 11 Groove 12 Lid 13 Brazing material 14 Opening 15 Small piece 16 Sealant 17 Real time Clock module 31, 32 Electrode pattern 41 Opening 42 Base 43 Lid 101 IC chip 102 Lead frame 103 Island 104 Au wire bonding wire 105 I / O lead terminal 106 Crystal oscillator

Claims (9)

[Claims] 1. A piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are built in a package, wherein the semiconductor integrated circuit is mounted on a base made of ceramic by flip-chip bonding and formed on the semiconductor integrated circuit. The bump and the electrode pattern formed on the base are electrically connected, and the piezoelectric vibrator is disposed between the base and the semiconductor integrated circuit and formed on the semiconductor integrated circuit. A piezoelectric device electrically connected to the bump for connecting the piezoelectric vibrator. 2. A piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are incorporated in a package, wherein the semiconductor integrated circuit is mounted on a base made of ceramic by flip chip bonding, and the base is formed by flipping the semiconductor integrated circuit. 2. The piezoelectric device according to claim 1, further comprising a groove sandwiched between mounting surfaces to be chip-bonded, wherein the piezoelectric vibrator is arranged in the groove. 3. A piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are incorporated in a package, wherein the piezoelectric vibrator is provided at a connection portion between the piezoelectric vibrator connecting bump formed on the semiconductor integrated circuit. 2. The piezoelectric device according to claim 1, further comprising an opening. 4. A piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are built in a package, wherein the semiconductor integrated circuit has an electrode pad for connecting an electrode pattern formed on a base on opposing sides. The piezoelectric device according to claim 1, further comprising a connection electrode pad of the piezoelectric vibrator on a side perpendicular to an opposite side. 5. A piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are built in a package, wherein an electrode pattern formed on a peripheral portion on a base made of ceramic is
2. The piezoelectric device according to claim 1, wherein the piezoelectric device is metallized with at least two metal layers. 6. A piezoelectric device in which a semiconductor integrated circuit and a piezoelectric vibrator are incorporated in a package, wherein the bump formed on the semiconductor integrated circuit is a bump formed by Au wire bonding. The piezoelectric device according to claim 1. 7. The piezoelectric device according to claim 1, wherein the piezoelectric vibrator is a quartz vibrator in a piezoelectric device having a semiconductor integrated circuit and a piezoelectric vibrator incorporated in a package. 8. The piezoelectric device according to claim 1, wherein the semiconductor integrated circuit is a real-time clock IC in a piezoelectric device having a semiconductor integrated circuit and a piezoelectric vibrator built in a package. 9. A step of forming a bump on each pad of the semiconductor integrated circuit; a step of mounting and connecting a piezoelectric vibrator to a bump for connecting a piezoelectric vibrator formed on the semiconductor integrated circuit; Using a flip-chip bonding method to connect and fix the base to a predetermined position on the base, mounting a lid (lid) on the base, and sealing the base; and using an opening provided in the base or the lid, A method for manufacturing a piezoelectric device, comprising: a step of laser processing a predetermined position of a piezoelectric vibrator to adjust a frequency; and a step of vacuum-sealing the opening in a vacuum atmosphere.