KR101787878B1 - Piezoresistive accelerometer - Google Patents

Abstract

A piezoresistive type accelerometer according to an embodiment includes: a support; A mass connected to the support and movable by an external force; A plurality of piezoresistors disposed between the support and the mass and deformed by movement of the mass; And a connection part disposed between the support body and the mass body to enable rotation of the mass body with respect to the support body, wherein the plurality of piezo resistor bodies are stretched or compressed by rotation of the mass body around the connection part, A resistance change can be caused in a plurality of piezoresistors.

Description

[0001] PIEZORESISTIVE ACCELEROMETER [0002]

More particularly, the present invention relates to a piezoresistive type accelerometer capable of measuring the magnitude of acceleration from a change in resistance due to deformation of a piezoresistive element, and a piezoresistive type accelerometer To a packaging method.

Today, accelerometers are widely used in mobile phones, motion recognition games, building vibration detection, automotive airbags, and military applications. Silicon-based accelerometers have advantages of high integration and miniaturization through mass production through MEMS (micro electro mechanical systems) process, and have advantages of fast response time which is characteristic of semiconductor devices.

For this reason, many researchers in the modern era have been working on the fabrication of accelerometers based on MEMS process and the study of working principles using microstructures. In an accelerometer manufactured through a MEMS process, various principles such as a piezoresistance type, a piezoelectric type, a capacitive type, a resonance type, and an optical type are used. Of these various types of accelerometers, piezo-resistive, piezoelectric, and capacitive types are widely used in industry.

Piezoresistive, piezoelectric, and capacitive accelerometers measure the change in the deformation of a sensing material or the change in spacing of a structure by an external force by converting it into an electrical signal.

Among them, the capacitive type and the piezoelectric type accelerometer have a relatively higher sensitivity than the piezoresistive type. However, in the case of a high impact, there is a problem of non-linearity in the case of a capacitance accelerometer, and a piezoelectric accelerometer has a problem of a zero-shift phenomenon in which the original signal can not be recovered after the shock is detected. Therefore, a piezoresistive type accelerometer is widely used in a high impact environment.

For example, KR 1998-0032658, filed on August 12, 1998, discloses a 'capacitive piezoresistive accelerometer'.

An object of the present invention is to provide a piezoresistive type accelerometer which is suitable for various impact ranges by adjusting the size of a mass and the thickness of a connection portion (hinge), and can be manufactured through dry etching.

An object of the present invention is to provide a piezo-resistive accelerometer which can easily form a Wheatstone bridge circuit, minimizes a structure, increase the degree of integration of the sensor with high stability, and improve productivity.

The object of the present invention is to provide a piezoresistive type accelerometer in which the mass body moves more stably when the impact is applied, and the mass body can move only perfectly in the vertical direction.

An object according to one embodiment is to measure the magnitude of acceleration by increasing or decreasing the resistance of a piezoresistive body and measuring the magnitude of impact when the shell is impacted when used in the military to determine whether the shell explodes And to provide a piezoresistive accelerometer that can be utilized.

According to an aspect of the present invention, there is provided a piezoresistive type accelerometer including: a support; A mass connected to the support and movable by an external force; A plurality of piezoresistors disposed between the support and the mass and deformed by movement of the mass; And a connection part disposed between the support body and the mass body to enable rotation of the mass body with respect to the support body, wherein the plurality of piezo resistor bodies are stretched or compressed by rotation of the mass body around the connection part, A resistance change can be caused in a plurality of piezoresistors.

According to one aspect of the present invention, a plurality of mass bodies are disposed symmetrically with respect to each other with respect to the support, the plurality of mass bodies comprising: a first mass body connected to a first side surface of the support body; And a second mass connected to a second side of the support opposite to the first side of the support, wherein the connection can be disposed on the first side and the second side.

According to one aspect of the present invention, the plurality of piezoresistors may include a first piezoresistive member and a second piezoresistor disposed in a bridge form between the first masses and the first side faces of the upper support member; And a third piezoresistive member and a fourth piezoresistor disposed in a bridge form between the second mass and the second side face of the upper support, wherein the first piezoresistive member, the second piezoresistive member, The resistor and the fourth piezoresistor may form a single Wheatstone bridge circuit.

According to one aspect of the present invention, the first piezoresistive member and the fourth piezoresistive member are arranged symmetrically with each other with the support interposed therebetween, and the second piezoresistive member and the third piezoresistive member are symmetrical .

According to one aspect of the present invention, when the first mass body or the second mass body is moved downward, the first or the fourth resistors are pulled to increase resistance, and the first mass body or the second mass body is moved upward The first piezoresistor or the fourth piezoresistor can be compressed and the resistance can be reduced.

According to one aspect of the present invention, the connecting portion is provided by a hinge, and the connecting portion has a length corresponding to the width of the mass body, and the connecting portion is formed between the center of the first piezoresistive body and the third piezoresistive body, And the fourth piezoelectric resistor.

According to one aspect of the present invention, the support includes a lower support to which the lower surface is bonded to the package substrate; And an upper support disposed on the upper surface of the lower support and connected to the side surface of the mass body, and a lower surface of the mass can be disposed apart from the upper surface of the lower support.

According to one aspect, the plurality of mass bodies may be disposed symmetrically with respect to each other about the upper support, and the plurality of piezo resistors may be arranged symmetrically or asymmetrically with respect to the upper support.

According to an aspect of the present invention, there is provided a piezoresistive type accelerometer including: a support; A plurality of masses connected to the support and movable by an external force; And a plurality of piezoresistors disposed in a bridge form between the support and the plurality of mass bodies and deformed by the movement of the mass body, wherein the plurality of piezo resistors are disposed on the front and back surfaces of the support body .

According to one aspect of the present invention, a plurality of Wheatstone bridge circuits are formed by the plurality of piezoresistors, and the plurality of Wheatstone bridge circuits comprise a first piezoresistor connected between the support and the plurality of mass bodies at the front face of the support, A first Wheatstone bridge circuit composed of a second piezoresistor, a third piezoresistor and a fourth piezoresistor; And a second Wheatstone bridge circuit consisting of a fifth piezoresistor, a sixth piezoresistor, a seventh piezoresistor and an eighth piezoresistor connected between the support and the plurality of masses at the back surface of the support.

According to an aspect of the present invention, there is provided a method of packaging a piezoresistive accelerometer, the method comprising: wire bonding the piezoresistive accelerometer; Applying an adhesive on a package substrate to which the piezoresistive accelerometer is to be bonded; Bonding the piezoresistive accelerometer to the package substrate; Bonding a wire bonded to the piezoresistive accelerometer to the package substrate; And mounting a cap on the piezoresistive accelerometer, wherein the piezoresistive accelerometer and the package substrate are provided with a plurality of electrode pads to correspond to each other.

According to an aspect of the present invention, there is provided a method of packaging a piezoresistive accelerometer, the method comprising: wire bonding the piezoresistive accelerometer to withstand a high impact; Bonding the piezoresistive accelerometer to a metal package; Bonding a wire bonded to the piezoresistive accelerometer to a substrate of the metal package; And a step of bonding a metal cap to the upper part of the metal package by welding, wherein a plurality of electrode pads may be provided on the substrate of the piezoresistive type accelerometer and the metal package, The corresponding wire may be provided to come out of the metal package.

According to the piezoresistive type accelerometer according to the embodiment, by adjusting the size of the mass and the thickness of the connection part (for example, hinge), it is suitable for various impact ranges, and the fabrication process can be simplified by manufacturing through dry etching.

According to the piezoresistive accelerometer according to the embodiment, the whitestone bridge circuit structure is easy, the structure is minimized, the structural stability at high impact is increased, and the degree of integration of the sensor is increased to improve the productivity.

According to the piezometric resistance type accelerometer according to the embodiment, when the impact is applied, the mass body moves more stably and the mass body can move perfectly only in the up and down direction.

According to the piezoresistive accelerometer according to the embodiment, the magnitude of the acceleration is measured by increasing or decreasing the resistance of the piezoresistive body. When the shell is used in the military, the magnitude of the impact when the impact is applied is measured, Or to determine whether the

1 (a) and 1 (b) illustrate a piezoresistive accelerometer according to one embodiment.
2 shows a driving principle of a piezoresistive type accelerometer according to an embodiment.
Fig. 3 shows a Wheatstone bridge circuit formed by a plurality of piezoresistors.
Figure 4 shows the formation of an additional Wheatstone bridge circuit on the back side of the upper support.
5 (a) to 5 (f) show a plurality of photomasks used for manufacturing a piezoresistive accelerometer according to an embodiment.
6 (a) to 6 (f) illustrate a manufacturing process of a piezoresistive type accelerometer according to an embodiment.
7 is an electron micrograph of the manufactured piezoresistive accelerometer.
8 is a flowchart showing a packaging method of a piezoresistive type accelerometer according to an embodiment.
9 (a) to 9 (e) illustrate how the manufactured piezoresistive accelerometer is packaged.
10 is a photograph of a packaging part and a packaging of the manufactured piezoresistive type accelerometer.

Hereinafter, embodiments will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals whenever possible, even if they are shown in different drawings. In the following description of the embodiments, detailed description of known functions and configurations incorporated herein will be omitted when it may make the best of an understanding clear.

In describing the components of the embodiment, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

FIG. 2 shows a principle of driving a piezoresistive type accelerometer according to an embodiment. FIG. 3 shows the principle of operation of the piezoresistive type accelerometer according to one embodiment. Fig. 4 shows a state in which an additional Wheatstone bridge circuit is formed on the back surface of the upper support. Fig.

1 (a) and 1 (b), a piezoresistive accelerometer 10 according to one embodiment may include a support 100, a mass 200, a piezoresistor 300, and a connection 400 have.

1 (b) is a cross-sectional view of the upper support 120 and the second mass 220 of FIG. 1 (a).

The support 100 may include a lower support 110 joined to a package substrate to be used for later packaging, for example, and an upper support 120 disposed on the upper surface of the lower support 110 .

At this time, the upper support 120 may be disposed perpendicular to the upper surface of the lower support 110. For example, a seating groove for the upper support 120 may be formed on the upper surface of the lower support 110 .

However, the shape of the support 100 is not limited thereto, and any structure can be used as long as the mass 200, the piezoresistor 300, and the connection portion 400 can be properly connected.

A plurality of mass bodies 200 may be connected to the support 100, in particular, the upper support 120.

The mass body 200 may include a first mass 210 disposed on a first side or a left side of the upper support 120 and a second mass 220 disposed on a second side or right side of the upper support 120 ).

The plurality of mass bodies 200 may be disposed symmetrically with respect to the upper support body 120 and the plurality of mass bodies 200 may be spaced apart from the lower and upper supports 110 and 120.

Each of the plurality of mass bodies 200 may be spaced apart from the upper surface of the lower support 110 and the plurality of mass bodies 200 may be spaced apart from each other on both sides of the upper support 120, As shown in Fig.

A plurality of piezoresistors 300 may be disposed between the support 100 and the mass body 200.

The plurality of piezoresistors 300 may be deformed by movement of the mass body 200 or rotation about the upper support 120 and may cause a resistance change when the plurality of piezoresistors 300 are stretched or compressed .

More specifically, the plurality of piezoresistors 300 include a first piezoresistor 310 and a second piezoresistor 320 disposed between the first masses 210 and the first side faces of the upper support 120, And a third piezoresistor 330 and a fourth piezoresistor 340 disposed between the first side of the upper support 120 and the second side of the upper support 120.

The first piezoelectric resistor 310 is provided in the form of a bridge to connect the first side of the upper support body 120 and the upper side of the first mass body 210. The second piezoelectric resistor 320 is connected to the upper support body 120, May be provided in the form of a bridge to connect the first side of the first mass body 210 to the lower side of the first mass body 210. The third piezoresistive body 330 is provided in the form of a bridge so as to connect the second side face of the upper support body 120 and the lower face of the second mass body 220, And may be provided in the form of a bridge to connect the second side to the upper surface of the second mass body 220.

The first and third piezoresistors 310 and 340 are disposed symmetrically with respect to each other with the upper support 120 interposed therebetween and the second piezoresist 320 and the third piezoresistor 330 are disposed symmetrically with respect to the And can be arranged symmetrically with respect to each other with the support 120 interposed therebetween.

On the other hand, the plurality of piezoresistors 300 may have a very thin thickness of several micrometers, thereby increasing the sensitivity of the accelerometer and not hindering the movement of the mass body 200.

As the thickness of the bridge type piezoresist 300 becomes thinner, the minute displacement of the mass body 200 does not act as deformation resistance. This means that the physical deformation of the piezoelectric resistor 300 easily occurs without interfering with the up and down movement of the mass body 200, so that the change of the resistance easily occurs.

In addition, a connecting part 400 may be disposed between the upper support 120 and the mass body 200. For example, the connection unit 400 may be hinged to allow the mass body 200 to rotate vertically with respect to the upper support 120.

Specifically, the connection portion 400 may be disposed on the first side and the second side of the upper support 120. In particular, the connection portion 400 may have a length corresponding to the width of the mass body 100 on the first side and the second side of the upper support 120.

The connecting portion 400 may be formed on the first side of the upper support 120 in the center of the first piezoelectric resistor 310 and the second piezoelectric resistor 320 or on the second side of the upper support 120, 330 and the fourth piezoresistive member 340. The first and second piezoresistors 340,

When the external force or impact is applied to the mass body 200, the mass body 200 can rotate around the connection portion 400 as the center axis have.

At this time, when the mass body 200 rotates, the plurality of piezoresistors 300 may be stretched or compressed.

Particularly, in the piezoresistive type accelerometer 10 according to the embodiment, the first mass body 210 and the second mass body 220 have the same size and are designed to be symmetrical with respect to the upper support body 120, Deformation of the piezoresistors 300 disposed on the left and right of the support 120 may be the same.

Although a plurality of mass bodies 200 are illustrated as being symmetrically disposed about the upper support body 120, the mass bodies 200 may be arranged asymmetrically with respect to the upper body 120 And a plurality of the piezoresistors 300 disposed between the plurality of mass bodies 200 and the upper support 120 may be arranged symmetrically or asymmetrically with respect to the upper support 120.

In addition, since the plurality of the piezoresistors 300 are arranged far from the connecting portion 400, the physical deformation of the plurality of piezoresistors 300 can be maximized.

The connection portion 400 described above may be designed differently depending on the impact range applied to the piezoresistive type accelerometer 10 according to the embodiment. For example, when the external force or the amount of impact applied to the piezoresistive type accelerometer 10 increases, the thickness of the connection portion 400 may be increased to increase the strength and the natural frequency of the piezoresistive type accelerometer 10. On the other hand, when the external force or the amount of impact applied to the piezoresistive type accelerometer 10 decreases, the thickness of the connection portion 400 may be relatively thinned to increase the sensitivity of the piezoresistive type accelerometer 10.

2, when a plurality of the piezoresistors 300 are constituted by the first piezoresistor 310, the second piezoresistor 320, the third piezoresistor 330 and the fourth piezoresistor 340 Each of the piezoresistors 300 may be composed of one bridge type piezoresistor.

Specifically, when an external impact is applied to the piezoresistive type accelerometer 10 according to one embodiment, the mass body 200 can be moved up and down while the connection portion 400 is bent.

The lengths of the first piezoresistor 310 and the fourth piezoresistor 340 connected to the upper surfaces of the first mass body 210 and the second mass body 220 may be increased when the mass body 200 is moved downward have. The increase in the lengths of the first and third piezoresistors 310 and 340 may lead to an increase in resistance of the first piezoresistor 310 and the fourth piezoresistor 340.

On the other hand, when the mass body 200 moves downward, the lengths of the second and third piezoresistors 320 and 330 connected to the lower surfaces of the first mass body 210 and the second mass body 220 are decreased . The reduction in the lengths of the second and third piezoresistors 320 and 330 may lead to a decrease in resistance of the second and third piezoresistors 320 and 330. [

When the external impact is transmitted in the opposite direction and the mass 200 is moved upward, the lengths of the second and third piezoelectric resistors 320 and 330 are increased, The resistance of the third piezoresistive body 330 is increased and the lengths of the first piezoresistor 310 and the fourth piezoresistor 340 are reduced so that the resistance of the first piezoresistor 310 and the fourth piezoresistor 340 Can be reduced.

3, the first piezoresistor 310, the second piezoresistor 320, the third piezoresistor 330, and the fourth piezoresistor 340 can form a Wheatstone bridge circuit.

At this time, when the voltage V _in is applied to the Wheatstone bridge circuit, the output voltage V _out can be expressed by the following equation.

On the other hand, assuming that the resistance change value of the piezoresistor 300, which is generated when an external impact is applied to the piezoresistance accelerometer 10 according to an embodiment, is much smaller than the initial resistance value of the piezoresistor 300, The ratio of the input / output voltage to the resistance change of the piezoresistor 300, which is generated when the resistance value of the piezoresistive element 300 is increased, can be expressed by the following equation.

At this time, the change in resistance of the piezoresistor 300 when the impact is applied may indicate a change in the output voltage value of the piezoresistive type accelerometer 10 according to the embodiment. To do this using the sensitivity of performance of the piezo-resistor-type accelerometer 10 in accordance with one embodiment (sensitivity) is the output voltage (V _out) to be output depending on the amount of impact (g _in) applied to the piezo-resistor-type accelerometer 10 It can be expressed as a ratio.

4, a plurality of piezoresistors 300 may be disposed on the back surface of the upper support 120 and the mass body 200 in the piezoresistive type accelerometer 10 according to one embodiment, A Wheatstone bridge circuit can be formed.

The plurality of piezoresistors 300 may further include a fifth piezoresistor 350, a sixth piezoresistor 360, a seventh piezoresistor 370 and an eighth piezoresistor 380.

For example, if the first piezoresistor 310, the second piezoresistor 320, the third piezoresistor 330, and the fourth piezoresistor 340 are disposed on the front surface of the upper support 120, Resistor 350, sixth piezoresistor 360, seventh piezoresistor 370 and eighth piezoresistor 380 may be disposed on the backside of upper support 120.

The fifth piezoelectric resistor 350 is provided on the upper surface of the first mass body 210 on the back surface of the upper support 120 symmetrically with the first piezoelectric resistor 310 in the form of a bridge, And the seventh piezoelectric resistor 370 is provided on the lower surface of the first mass body 210 in the form of a bridge symmetrically with the second piezoelectric resistor 320 on the back surface of the upper support 120. The third piezoelectric resistor 330, And the eighth piezoelectric resistor 380 is symmetrically provided on the lower surface of the second mass body 220 on the rear surface of the upper supporter 120 and the eighth piezoelectric resistor 380 is provided on the rear surface of the upper supporter 120 in symmetry with the fourth piezoelectric resistor 340, In the form of a bridge on the upper surface of the second mass body 220.

Therefore, a first Wheatstone bridge circuit is formed on the front surface of the upper support 120 by the first piezoresistor 310, the second piezoresistor 320, the third piezoresistor 330 and the fourth piezoresistor 340 A second Wheatstone bridge circuit is formed on the back surface of the upper support body 120 by the fifth piezoresistor 350, the sixth piezoresistor 360, the seventh piezoresistor 370 and the eighth piezoresistor 380 .

The mass body 200 and the plurality of the piezoresistors 300 are disposed symmetrically with respect to the front and back surfaces of the upper support 120 so that the piezoresistive type accelerometer 10 is symmetrically symmetrical The mass body 200 can move more stably and the mass body 200 can move more completely in the vertical direction.

A piezoresistive type accelerometer according to one embodiment of the present invention has been described, and a method of manufacturing the piezoresistance type accelerometer according to one embodiment will be described below.

As an embodiment, a method of fabricating a silicon on insulator (SOI) wafer in which an oxide film (silicon dioxide) and silicon are sequentially stacked on a silicon substrate is illustrated.

FIGS. 5A to 5F show a plurality of photomasks used for manufacturing a piezoresistive accelerometer according to an embodiment, and FIGS. 6A to 6F are cross- Fig. 7 is an electron micrograph of the manufactured piezoresistive accelerometer. Fig.

5 (a) to 5 (f), a total of five photomasks can be used to fabricate a piezoresistive silicon accelerometer.

Fig. 5 (a) is a photomask which defines a piezoresistive region through ion implantation as a first photomask. 5 (b) is a second photomask, which is an oxide film patterning photomask for defining an Ohmic contact region for electrical contact between the piezoelectric resistor defined by the first photomask and the metal electrode. FIG. 5 (c) is a photomask which defines a metal wiring definition and a wire bonding area through a wet etching process as a third photomask. 5 (d) is a photomask 4 for manufacturing a mass body and a connection portion of the accelerometer by a dry etching process. 5 (e) is a photomask for producing a mass body, a connecting portion, and a plurality of piezoresistors of an accelerometer by a etching process. 5 (f) shows the arrangement of the photomask patterns 1 through 5 described above.

6 (a) to 6 (f), a piezoresistive type accelerometer according to an embodiment can be manufactured as follows.

The first step in fabricating the piezoresistive accelerometer is to form a piezoresist.

6 (a) shows an oxide film patterning process to be used as a photomask in the ion implantation process.

First, an oxide film is grown by an oxide film growth process in a furnace. A photoresist pattern is formed through a photolithography process using a photomask 1 that defines a resist-resistant region, and then an oxide film patterning is performed. Then, ions are implanted.

6 (b) shows a process for depositing an oxide film and forming a metal electrode.

First, an oxide film is deposited. Then, the photolithography process is performed using the second photomask, and then the oxide film patterning is performed.

6 (c) and 6 (d) show a metal deposition process and a circuit patterning process for wiring, respectively.

First, aluminum (Al) is deposited.

Thereafter, the photolithography process is performed using the photomask 3. Al is etched using the patterned photoresist as an etch mask.

Meanwhile, the piezoresistive type accelerometer according to an embodiment of the present invention is divided into an upper process for etching the mass body, the bridge type piezoresistive body and the connection portion, and a lower process for etching the connection portion and the support to fabricate the mass body, the bridge type piezoresistor, and the connection portion.

6 (e) shows the etching process of the connecting portion and the support.

The photolithography process is performed with the photomask No. 4, and the photoresist is used as an etching photomask to etch the oxide film and the silicon.

Fig. 6 (f) shows a process for fabricating a bridge type piezoresist, a connection portion and a mass via an upper process.

First, the photolithography process is performed with the photomask 5, and the oxide film is etched using the photoresist as an etch-resistant mask. The process is then followed by DRIE to complete the shape of the bridge-type piezoresistors, connections and masses.

Finally, the dicing process is performed to separate the piezoresistive accelerometer manufactured as a unit.

In addition, a piezoresistive accelerometer manufactured by the method described above with reference to Fig. 7 can be confirmed. 7b) shows a bridge type piezoresistor 300 disposed between a support and a mass, and Figs. 7c) and d) show a connection 400 connected between the support and the mass 200. Fig.

Hereinafter, packaging of the piezoresistive type accelerometer fabricated as described above will be described.

FIG. 8 is a flowchart showing a packaging method of a piezoresistive accelerometer according to an embodiment. FIGS. 9 (a) to 9 (e) illustrate how the manufactured piezoresistive type accelerometer is packaged, This is a photograph of packaging parts and packaging of a resistive accelerometer.

Referring to FIG. 8, the piezoresistive accelerometer according to one embodiment can be roughly packaged as follows.

First, wire bonding is performed to the piezoresistive accelerometer manufactured as described above (S10), and an adhesive is applied on the package substrate to which the piezoresistive accelerometer is to be bonded (S20). Then, the piezoresistive accelerometer is bonded on the package substrate (S30), and a wire primarily bonded to the piezoresistive accelerometer is secondarily bonded on the package substrate (S40). Then, the cap is mounted on the piezoresistive accelerometer (S50).

Specifically, FIG. 9 (a) shows a state in which the piezoresistive type accelerometer 10 according to the embodiment is packaged. FIG. 9 (b) shows a state in which the piezo-resistive accelerometer 10 according to the embodiment is wire-bonded in the primary direction. 9 (c) shows a state in which an epoxy adhesive is applied on a package substrate 20 provided with a ceramic substrate to which a piezoresistive accelerometer 10 according to an embodiment is to be bonded. Thereafter, the curing of the adhesive proceeds. Fig. 9 (d) shows the bonding of the wires bonded to the package substrate 20 and the piezoresistive accelerometer 10 according to an embodiment in the secondary wire bonding process.

For such wire bonding, the piezoresistive type accelerometer 10 and the package substrate 20 according to an embodiment may be provided with electrode pads to correspond to each other. For example, the piezoresistive accelerometer 10 according to an embodiment may include four electrode pads, and the package substrate 20 may also include four electrode pads.

Finally, as shown in FIG. 9 (e), after the completion of the secondary wire bonding, an epoxy adhesive is applied to the joint portion between the cap and the package substrate 20 and then bonded. The packaging of the piezoresistive type accelerometer 10 is completed by curing the epoxy adhesive applied to the junction of the cap and the package substrate 20. [

In this regard, FIG. 10A is a package substrate actually made of ceramic board, FIG. 10B is a package substrate provided by ceramic board, FIG. 10C is a view in which a piezoresistive accelerometer is combined on a package substrate, The cap is packaged with a piezoresistive accelerometer coupled to the substrate.

Also, although not specifically shown, a piezoresistive accelerometer according to an embodiment can be roughly packaged as follows.

First, a piezoresistive accelerometer is bonded to the inside of the metal package, and a wire bonded to the piezoresistive accelerometer is bonded on the substrate of the metal package. The metal cap can be attached and welded by welding. At this time, a plurality of electrode pads may be provided to correspond to the substrates of the piezoresistive type accelerometer and the metal package, and electric wires corresponding to the electrode pads may be provided to extend out of the metal package.

Although the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And various modifications and changes may be made thereto without departing from the scope of the present invention. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

10: piezoresistive accelerometer
100: Support
110: Lower support
120: upper support
200: mass
300:
400: Connection

Claims (11)

A support;
A mass connected to the support and movable by an external force;
A plurality of piezoresistors disposed between the support and the mass and deformed by movement of the mass; And
A connection disposed between the support and the mass to enable rotation of the mass relative to the support;
Lt; / RTI >
Wherein the plurality of piezoresistors are tensioned or compressed by the rotation of the mass about the connecting portion to cause a resistance change in the plurality of piezoresistors,
A plurality of mass bodies are arranged symmetrically with respect to each other about the support,
Wherein the plurality of mass bodies comprise:
A first mass connected to a first side of the support; And
A second mass connected to a second side of the support opposite the first side of the support;
Lt; / RTI >
And the connection portion is disposed on the first side surface and the second side surface.
delete The method according to claim 1,
The plurality of the piezoresistors may be formed of,
A first piezoresist and a second piezoresistor disposed in a bridge form between the first mass and the first side of the support; And
A third piezoelectric resistor and a fourth piezoelectric resistor disposed in the form of a bridge between the second mass and the second side of the support;
Lt; / RTI >
Wherein the first piezoresistive member, the second piezoresistor, the third piezoresistor, and the fourth piezoresistor form a single Wheatstone bridge circuit.
The method of claim 3,
Wherein the first and the fourth piezoresistors are arranged symmetrically with respect to each other with the support interposed therebetween, and the second piezoresistive element and the third piezoresistor are arranged symmetrically with respect to each other with the support interposed therebetween, Accelerometer.
5. The method of claim 4,
When the first mass body or the second mass body is moved downward, the resistance of the first or fourth piezo resistor is increased to increase resistance. When the first mass body or the second mass body is moved upward, Wherein the first piezoresistor or the fourth piezoresistor is compressed to reduce the resistance.
The method of claim 3,
The connecting portion is provided with a hinge,
The connecting portion has a length corresponding to the width of the mass body,
And the connecting portion is disposed at the center of the first and second piezoresistors and at the center of the third and fourth piezoresistors.
The method according to claim 1,
Wherein the support comprises:
A lower support joined to the lower surface of the package substrate; And
An upper support disposed on the upper surface of the lower support and connected to the side surface of the mass;
Lt; / RTI >
Wherein the lower surface of the mass body is spaced apart from the upper surface of the lower support.
8. The method of claim 7,
Wherein the plurality of mass bodies are disposed symmetrically with respect to each other about the upper support body, and the plurality of piezo resistors are symmetrically or asymmetrically arranged with respect to the upper support body.
A support;
A plurality of masses connected to the support and movable by an external force; And
A plurality of piezoresistors arranged in a bridge between the support and the plurality of mass bodies and deformed by the movement of the masses;
Lt; / RTI >
The plurality of piezoresistors are disposed on the front surface and the back surface of the support,
Wherein the plurality of mass bodies are disposed symmetrically with respect to each other about the support,
Wherein the plurality of mass bodies comprise:
A first mass connected to a first side of the support; And
A second mass connected to a second side of the support opposite the first side of the support;
And an accelerometer.
10. The method of claim 9,
A plurality of Wheatstone bridge circuits are formed by the plurality of piezoresistors,
Wherein the plurality of Wheatstone bridge circuits comprises:
A first Wheatstone bridge circuit composed of a first piezoresistor, a second piezoresistor, a third piezoresistor and a fourth piezoresistor connected between the support and the plurality of masses in front of the support; And
A second Wheatstone bridge circuit consisting of a fifth piezoresistor, a sixth piezoresistor, a seventh piezoresistor and an eighth piezoresistor connected between the support and the plurality of masses at the backside of the support;
And an accelerometer.
delete

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