JPH06216396A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain an acceleration sensor in which automation of an assembling operation can be expedited. CONSTITUTION:A cantilever 14 for detecting acceleration is formed of a glass board 15 supported as a cantilever to an IC chip 12 and formed on its upper surface with a Cr thin film for a strain gage. The cantilever 14 is mounted on a hybrid IC 82 in a state supported as a cantilever on the chip 12. Thus, the cantilever 14 is formed in smaller size than that of conventional piezoelectric element. An electric connection of the cantilever 14 to the chip 12 and an electric connection of the chip 12 to the IC 82 can be conducted by wire bonding. Accordingly, when an automatic bonder is used, automation of assembling operation can be expedited, and a manufacturing cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor,
Particularly, the present invention relates to an acceleration sensor having a cantilever for detecting a strain caused by acceleration.

[0002]

2. Description of the Related Art A conventional example of this type of acceleration sensor is shown in FIG. The acceleration sensor 80 includes a hybrid IC (a strip line formed on a ceramic substrate, GaAsF formed on a ceramic substrate) that constitutes a mounting substrate.
ET chip, resistor, capacitor, coil, etc.) 82, SMD (Surface Mounted Device) 84 forming a signal processing circuit mounted on the hybrid IC 82, and one of them on the hybrid IC 82. One end of the surface (lower surface in FIG. 5) has a cantilever 86 for acceleration detection of a piezoelectric body made of ceramics such as PZT, which is soldered. The electrical connection between the cantilever 86 and the circuit including the SMD 84 on the hybrid IC 82 is such that the other surface of the cantilever 86 (the upper surface in FIG. 5) and the both ends of the cantilever 86 are joined to each other using solder 88 or a conductive adhesive. The wiring 90 is used.

[0003]

However, in the above-mentioned conventional acceleration sensor 80, the cantilever 8 is used.
Since the electrical connection between 6 and the circuit including the SMD 84 on the hybrid IC 82 is made by soldering or the like, the assembly workability is poor, and it is particularly difficult to promote automation of the assembly work. Further, the piezoelectric cantilever 86 has a structure in which one end portion of one surface thereof is soldered onto the hybrid IC 82 and most of the longitudinal direction thereof is projected from the hybrid IC 82 to the outside. Therefore, there is a problem that the acceleration sensor 80 becomes large as a whole and the manufacturing cost becomes high.

The present invention has been made in view of such circumstances, and an object thereof is to provide an acceleration sensor which can promote automation of assembly work in particular.

[0005]

An acceleration sensor according to the present invention is a mounting board having a wiring portion formed on an upper surface thereof, a signal processing circuit device mounted on the mounting board, and the signal processing circuit device. An acceleration detecting cantilever which is cantilevered above and has a strain gauge metal thin film formed on at least one surface thereof.

[0006]

According to the above structure, the acceleration detecting cantilever is cantilevered on the signal processing circuit device and is composed of the substrate having the strain gauge metal thin film formed on at least one surface thereof. The acceleration detecting cantilever is made smaller than that of the conventional piezoelectric body. Further, since the acceleration detecting cantilever is mounted on the mounting board in a state of being cantilevered on the signal processing circuit device, the acceleration detecting cantilever and the signal processing circuit device, for example, an IC Electrical connection with the chip and electrical connection between the signal processing circuit device and the mounting substrate can be performed using wire bonding or flip chip bonding, which is one of semiconductor mounting technologies. Therefore, if an automatic bonder, a flip chip bonder, or the like is used, automation of the assembling work can be promoted, thereby reducing the manufacturing cost.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a schematic front view of an acceleration sensor 10 according to the first embodiment. This acceleration sensor 1
Reference numeral 0 denotes a hybrid IC 82 that constitutes a mounting board, and I as a signal processing circuit device die-bonded (also referred to as a mount) on the hybrid IC 82.
A C chip 12 and a glass substrate 15 in a cantilevered state in which one longitudinal end (right end in FIG. 1) of one surface (lower surface in FIG. 1) of the IC chip 12 is anodically bonded (anodic bonded). And have. Here, the anodic bonding is a kind of voltage application bonding method in which glass and metal or glass and silicon single crystal (Si wafer) are bonded under a predetermined temperature condition by applying a high voltage, for example, a voltage of about 300V. Say. Further, the die bonding is performed as follows. That is, epoxy resin 1 containing Ag (silver)
6 or the like is applied in advance to a predetermined area on the hybrid IC 82, and the IC chip 12 is pressed against this and temporarily fixed,
Then, the epoxy resin 16 containing silver is cured at 150 to 200 ° C., and the IC chip 12 and the strip line (metal wiring) on the hybrid IC 82 are electrically connected by the silver in the epoxy resin 16.

A chromium-based thin film (Cr thin film) 18 as a strain gauge metal thin film is formed on the other surface (upper surface in FIG. 1) of the glass substrate 15 by, for example, an evaporation method, a sputtering method, a CVD method, or the like. Thus, an acceleration detecting cantilever (hereinafter, appropriately abbreviated as "cantilever") is configured. The bonding pad formed on the upper surface of the cantilever 14 and the bonding pad of the IC chip 12, the bonding pad of the IC chip 12 and a predetermined region on the hybrid IC 82 are wire-bonded (lead-bonded) using the bonding wires 20 and 22. There is. More specifically, the bonding wires 20 and 22 have, for example, a diameter of 5
A 0 μm aluminum (Al) wire is used, the tip of this aluminum wire is pressed onto the bonding pad of the cantilever 14 (or the bonding pad of the IC chip 12), and ultrasonic waves are applied to bond the aluminum wire and the bonding pad of the cantilever 14. (Or, the aluminum wire and the bonding pad of the IC chip 12) are strongly bonded. The tip of the aluminum wire is also joined to a predetermined region on the hybrid IC 82 by the same method.

In FIG. 1, the other end of the cantilever 14 in the longitudinal direction is arranged so as not to extend outside the substrate of the hybrid IC 82.

As described above, according to the acceleration sensor 10 of this embodiment, the acceleration detecting cantilever 14 is
Since the glass substrate 15 and the Cr thin film 18 formed on the upper surface of the glass substrate 15 are used, the cantilever 14 is made smaller than that of the conventional piezoelectric body, and the cantilever 14 is hybrid IC 82.
Since it is not directly attached to the IC chip 12 but is mounted via the IC chip 12 as a device for a signal processing circuit, at the time of this mounting, the connection between the cantilever 14 and the IC chip 12 and the connection between the IC chip 12 and the hybrid IC 82 are performed. , Which is one of the semiconductor mounting technologies, can be carried out by wire bonding, and the use of an automatic bonder or the like has the effect that the automation of assembly work can be promoted and therefore the manufacturing cost can be reduced. .

Further, in the case of the acceleration sensor 10 of the present embodiment, die bonding, which is included in a post-process of semiconductor manufacturing for mounting the IC chip 12 on the hybrid IC 82 (in the case of semiconductor manufacturing, a film-shaped lead frame is used. Is used for bonding the glass substrate 15 and the IC chip 12 by anodic bonding, which is a kind of voltage application bonding method.
Almost complete automation of assembly work is possible.

Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be simplified or omitted.

The acceleration sensor 30 of the second embodiment has a hybrid IC 82, an IC chip 12 flip-chip bonded on the hybrid IC 82,
This IC chip 12 has a cantilever 14 having one surface (the lower surface in FIG. 2) on one side in the longitudinal direction (the right end in FIG. 2) anodically bonded to the IC chip 12. Here, flip-chip bonding is a kind of face-down bonding in wireless bonding, and means that the surface electrode of the IC chip 12 and the wiring electrode of the hybrid IC 82 are opposed to each other and are directly bonded by heating and pressing. . In this embodiment, the solder bumps 24 are interposed between the surface electrodes of the IC chip 12 and the wiring electrodes of the hybrid IC 82, and the solder bumps 24 join the two. Flip chip bonding can be automatically performed by a device called a flip chip bonder.

The cantilever 14 and an unillustrated wiring (back surface electrode) formed on the back surface of the IC chip 12 are wire-bonded using a bonding wire 20, and I
The wiring formed on the back surface of the C chip 12 and the hybrid I
C82 is wire-bonded using the bonding wire 22.

According to the second embodiment constructed as described above, the same effect as that of the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described with reference to FIG. Here, the same components as those in the first and second embodiments described above are designated by the same reference numerals, and the description thereof will be simplified or omitted.

The acceleration sensor 50 of the third embodiment is characterized in that the cantilever 14 is flip-chip bonded to the back surface of the IC chip 12 by using the solder bumps 26 in the second embodiment described above. This is the same as the second embodiment.

According to the third embodiment as well, the same effects as those of the first and second embodiments can be obtained, and since anodic bonding is not performed, the assembly work can be fully automated by fully utilizing the semiconductor mounting technology. It is possible.

Next, a fourth embodiment of the present invention will be described with reference to FIG. Here, the same components as those in the first and second embodiments described above are designated by the same reference numerals, and the description thereof will be simplified or omitted.

In the acceleration sensor 70 of the fourth embodiment,
The orientation of the cantilever 14 is opposite to that of the second embodiment described above. Instead of the IC chip 12 so as to support the cantilever 14 in a cantilever manner, an IC chip 28 having one end on the back surface side projected to the back surface side is used as a device for a signal processing circuit. The cantilever 14 and the IC chip 12 are joined by anodic bonding. Further, the Cr thin film 18 on the upper surface of the cantilever 14 is a hybrid I
The stud 32 provided on the C82 is wire-bonded using the bonding wire 20. Therefore, the back surface electrode of the IC chip 28 and the hybrid IC 82 are
The connection with the upper strip line is unnecessary. The other structure is the same as that of the second embodiment described above.

Also according to the fourth embodiment, the same effects as those of the first and second embodiments can be obtained. The cantilever 14
The glass substrate does not necessarily have to be a glass substrate, but instead of this, a substrate made of a silicon single crystal (Si wafer) or another substrate capable of forming a metal thin film for a strain gauge may be used. Further, the strain gauge metal thin film formed on this substrate is not limited to a Cr-based thin film,
Other metal thin films may be used.

[0023]

As described above, according to the present invention,
The acceleration detecting cantilever is cantilevered on a signal processing circuit device (for example, an IC chip), and is composed of a substrate having a strain gauge metal thin film formed on at least one surface thereof. Since the cantilever is miniaturized and mounted on a mounting substrate (for example, a hybrid IC) in a cantilevered state on a signal processing circuit device (for example, an IC chip), the cantilever and the signal processing circuit are mounted during this mounting. The electrical connection with the device and the electrical connection between the signal processing circuit device and the mounting substrate can be performed using wire bonding or flip chip bonding, which is one of the semiconductor mounting technologies. Therefore, if an automatic bonder, a flip chip bonder, or the like is used, automation of the assembling work can be promoted, and this has an unprecedented excellent effect that the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a first embodiment of the present invention.

FIG. 2 is a schematic front view showing a second embodiment of the present invention.

FIG. 3 is a schematic front view showing a third embodiment of the present invention.

FIG. 4 is a schematic front view showing a fourth embodiment of the present invention.

FIG. 5 is a schematic front view showing a conventional example.

[Explanation of symbols]

 10 Acceleration Sensor 12 IC Chip (Signal Processing Circuit Device) 14 Acceleration Detection Cantilever 15 Glass Substrate (Substrate) 18 Cr Thin Film (Metal Thin Film for Strain Gauge) 28 IC Chip (Signal Processing Circuit Device) 30 Acceleration Sensor 50 Acceleration Sensor 70 Accelerometer 82 Hybrid IC (Mounting board)

Claims (1)

[Claims] 1. A mounting board having a wiring portion formed on an upper surface thereof, a signal processing circuit device mounted on the mounting board, and a cantilevered support on the signal processing circuit device. An acceleration sensor, comprising: an acceleration detecting cantilever formed of a substrate on which a metal thin film for a strain gauge is formed.