JP2006300905A - Acceleration sensor and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acceleration sensor that can suppress the variations of the output characteristics caused, by connecting the padding of an acceleration sensor chip with the electrode of a package and also suppress the excessive displacement of an overlapped part, and to provide a method of manufacturing the same. <P>SOLUTION: In the acceleration sensor, the package 3 has a plurality of electrodes 33 that are electrically connected with each of the plurality of the paddings 16 in the main surface side of the acceleration sensor chip 1 on the inner bottom 32a of a storing recess 32 in a package body 31. The padding 16 is electrically connected with the electrode 33 via a stress relaxation layer 4 consisting of conductive adhesive. A space, which can displace the weight part 12, is formed between the inner bottom 32a and acceleration sensor chip 1 of the storing recess 32 of the package body 31, and the sum total of the padding 16 overlapped in the thickness direction, stress relaxation layer 4 and electrode 33 is set so that the package body 31 functions as a stopper for controlling the excessive displacement of the overlapped part 12. The method of manufacturing the acceleration sensor is also disclosed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an acceleration sensor used for automobiles, aircraft, home appliances, and the like, and a method for manufacturing the same.

  Conventionally, as a semiconductor acceleration sensor of a method for detecting acceleration as a change in resistance value due to strain of a gauge resistor composed of a piezoresistor, four weight portions arranged inside a rectangular frame-shaped frame portion are extended in four directions. An acceleration sensor chip that is swingably supported by a frame portion via a flexure portion is packaged so that accelerations in three directions orthogonal to each other can be detected, and output values corresponding to the accelerations in each direction can be obtained individually. An acceleration sensor has been proposed (see, for example, Patent Document 1).

  For example, as shown in FIG. 10, this type of acceleration sensor includes an acceleration sensor chip 1 and a package 3 that houses the acceleration sensor chip 1.

  In the acceleration sensor chip 1, the weight portion 12 disposed inside the frame portion 11 having a rectangular frame shape swings on the frame portion 11 via four flexible portions 13 having flexibility on the main surface side of the acceleration sensor chip 1. It is supported freely.

  The weight portion 12 is continuously integrated into each of the rectangular parallelepiped core portion 12a supported by the frame portion 11 via the four flexure portions 13 and the four corners of the core portion 12a when viewed from the main surface side of the acceleration sensor chip 1. And four accompanying portions 12b having a rectangular parallelepiped shape connected to each other. Here, each of the accompanying portions 12b is in a space surrounded by the frame portion 11 and the core portion 12a and the two bent portions 13 and 13 extending in a direction orthogonal to each other when viewed from the main surface side of the acceleration sensor chip 1. The slits 14 are formed between each of the accompanying portions 12b and the frame portion 11, and the interval between the adjacent accompanying portions 12b with the bending portion 13 interposed therebetween is longer than the width dimension of the bending portion 13. ing.

  The acceleration sensor chip 1 described above can detect accelerations in three directions orthogonal to each other, and has a rectangular frame on a plane orthogonal to the thickness direction of the acceleration sensor chip 1 as shown on the right side of FIG. If the direction along one side of the frame portion 11 is defined as the x-axis direction, the direction along the side perpendicular to the one side is defined as the y-axis direction, and the thickness direction of the acceleration sensor chip 1 is defined as the z-axis direction, the weight portion 12 A piezoresistor (not shown) whose resistance value changes due to distortion generated in the flexure 13 due to the displacement of the flexure 13 is formed at an appropriate position of each flexure 13, and these piezoresistors detect a bridge circuit that detects the acceleration of each axis. They are connected by wirings (not shown) (diffusion layer wiring, metal wiring, etc.) so as to be configured.

  In manufacturing the above-described acceleration sensor, the frame portion 11 is attached to the inner bottom surface 32a with an adhesive (for example, an epoxy resin or the like) with the back surface of the acceleration sensor chip 1 facing the inner bottom surface 32a of the housing recess 32 of the package body 31. ) And the pad 16 provided on the frame portion 11 on the main surface side of the acceleration sensor chip 1 and the peripheral portion of the storage recess 32 on the one surface of the package body 31. Each electrode 35 is electrically connected through a bonding wire W made of a fine gold wire. Here, in the wire bonding process for bonding each bonding wire W to each pad 16 and each electrode 25, ultrasonic vibration of about 60 kHz to 120 kHz is transmitted to the bonding wire W, and the bonding wire W, each pad 16 and each electrode are connected. In general, an ultrasonic wire bonding method for joining each of the electrodes 35 is employed.

In the above-described acceleration sensor, the package body 31 of the package 3 functions as a stopper that restricts excessive displacement of the weight portion 12 in the negative z-axis direction, and the package lid (not shown) closes the one surface of the package body 31. 2) functions as a stopper that restricts excessive displacement of the weight portion 12 in the positive z-axis direction, so that the weight portion 12 is not excessively displaced and the bending portion 13 and the like are prevented from being damaged. be able to.
JP 2004-177233 A (paragraphs [0018]-[0028] and FIG. 1)

  However, in the acceleration sensor having the configuration shown in FIG. 10, when one end portion of the bonding wire W is bonded to each pad 16 provided on the frame portion 11 of the acceleration sensor chip 1, ultrasonic vibration of about 60 kHz to 120 kHz is generated. Is transmitted to the bonding wire W, and the bonding wire W and the pad 16 of the acceleration sensor chip 1 are bonded to each other. Therefore, in the wire bonding process, stress caused by the ultrasonic waves is generated in the frame portion 11, and the stress is deflected portion 13. There is a problem that the resistance value of the piezoresistor is changed by being transmitted to the formation site of the piezoresistor and causing distortion. In particular, as shown in FIG. 10A, when the pad 16 is formed on only two sides along the x-axis direction among the four sides of the rectangular frame-shaped frame portion 11, the pad 16 is formed along the y-axis direction. Since the stress caused by the ultrasonic waves is easily transmitted to the two flexures 13, the output characteristic of the bridge circuit that detects the acceleration in the x-axis direction is different from the output characteristic of the bridge circuit that detects the acceleration in the y-axis direction. There was a bug that it was.

  The present invention has been made in view of the above-described reason, and the object thereof is to suppress fluctuations in output characteristics due to connection between the pads of the acceleration sensor chip and the electrodes of the package, and excessive weight portions. An object of the present invention is to provide an acceleration sensor capable of suppressing displacement and a manufacturing method thereof.

  According to the first aspect of the present invention, the weight portion arranged inside the frame-like frame portion is supported by the frame portion so as to be swingable through four bending portions extending from the weight portion in four directions, and is provided in the bending portion. An acceleration sensor chip in which a plurality of pads electrically connected to the gauge resistor protrudes from the frame on the main surface side, and a package body and a package body in which a storage recess for storing the acceleration sensor chip is formed on one side A package having a plurality of electrodes provided between the inner bottom surface of the housing recess and the main surface of the acceleration sensor chip facing the inner bottom surface and electrically connected to each of the plurality of pads of the acceleration sensor chip, The pads and electrodes facing each other in the thickness direction of the acceleration sensor chip are electrically connected via a stress relaxation layer made of a conductive adhesive, and the package in the thickness direction is packaged. A space is formed between the inner bottom surface of the storage recess of the main body and the acceleration sensor chip so that the weight can be displaced, and the package body functions as a stopper for restricting excessive displacement of the weight. The total thickness of the pad, the stress relieving layer, and the electrode that overlap each other is set.

  According to the present invention, the pad of the acceleration sensor chip and the electrode of the package can be electrically connected without using a bonding wire, and the stress relaxation made of the conductive adhesive is provided between the pad and the electrode. Because the layer is interposed and stress is not easily transmitted from the package body to the acceleration sensor chip, it is possible to prevent stress from being generated in the frame part due to connection between the pad of the acceleration sensor chip and the electrode of the package, and fluctuation of output characteristics In addition, a space is formed between the inner bottom surface of the housing recess of the package body and the acceleration sensor chip in the thickness direction of the acceleration sensor chip so that the weight portion can be displaced. A pad and a stress relaxation layer that overlap in the thickness direction so as to function as a stopper that restricts excessive displacement of the weight portion; Since is set the sum of the thickness of the electrode, the package body becomes to have a function as a stopper for restricting excessive displacement of the weight portion, it is possible to suppress excessive displacement of the weight portion.

  According to a second aspect of the present invention, in the first aspect of the invention, the stress relaxation is applied to at least one of the pad formation portion of the frame portion and the electrode formation portion of the inner bottom surface of the housing recess of the package body. A convex portion protruding to the layer side is formed.

  According to this invention, a space having a gap length corresponding to the allowable displacement amount of the weight portion in the thickness direction is easily ensured between the weight portion and the inner bottom surface of the housing recess of the package body. Is possible.

  The invention of claim 3 is the invention of claim 1 or 2, characterized in that the stress relaxation layer contains agglomerates.

  According to this invention, a space having a gap length according to the allowable displacement amount of the weight portion in the thickness direction of the acceleration sensor chip is easily formed between the weight portion and the inner bottom surface of the housing recess of the package body. In addition, it is possible to increase the accuracy of the gap length.

  The invention of claim 4 is characterized in that, in the invention of claim 3, the agglomerates are made of a conductive material, and the grain size of the agglomerates and the thickness of the stress relaxation layer are set equal.

  According to the present invention, the distance between the pad and the electrode that overlap in the thickness direction of the acceleration sensor chip can be made uniform, and due to the variation in the thickness of the stress relaxation layer, It is possible to suppress the occurrence of distortion.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the electrode is disposed at a predetermined distance from the inner bottom surface of the package main body and is supported by the package main body in the thickness direction. It is characterized by having flexibility.

  According to the present invention, a space having a gap length corresponding to the allowable displacement amount of the weight portion in the thickness direction of the acceleration sensor chip is further formed between the weight portion and the inner bottom surface of the housing recess of the package body. It can be secured easily.

  According to a sixth aspect of the present invention, the weight portion disposed inside the frame-shaped frame portion is supported by the frame portion so as to be swingable through four bending portions extending from the weight portion in four directions, and is provided in the bending portion. An acceleration sensor chip in which a plurality of pads electrically connected to the gauge resistor protrudes from the frame on the main surface side, and a package body and a package body in which a storage recess for storing the acceleration sensor chip is formed on one side And a package having a plurality of electrodes provided between the inner bottom surface of the housing recess and the back surface of the acceleration sensor chip facing the inner bottom surface and electrically connected to each of the plurality of pads of the acceleration sensor chip. The sensor chip has a plurality of through-wirings that are electrically connected to each pad and penetrated in the thickness direction, and each through-wiring provided on the back surface of the acceleration sensor chip. A plurality of backside pads electrically connected to each other, and the backside pad and the electrode overlapping in the thickness direction are electrically connected via a stress relaxation layer made of a conductive adhesive. To do.

  According to the present invention, the pad on the main surface side of the acceleration sensor chip and the electrode of the package are electrically connected via the through wiring, the back pad, and the stress relaxation layer, so that the acceleration sensor can be used without using a bonding wire. The pad of the chip and the electrode of the package can be electrically connected, and a stress relaxation layer made of a conductive adhesive is interposed between the back pad and the electrode, so that the package main body and the acceleration sensor chip Since stress is difficult to be transmitted, it is possible to prevent stress from being generated in the frame portion due to the connection between the pad of the acceleration sensor chip and the electrode of the package, and to suppress fluctuations in output characteristics. The thickness direction of the acceleration sensor chip between the inner bottom surface of the housing recess and the acceleration sensor chip in the thickness direction of the chip Since a space with a gap length corresponding to the total thickness of the backside pad, stress relaxation layer, and electrode that overlaps is formed, the package body functions as a stopper that regulates excessive displacement of the weight part. It is possible to suppress the excessive displacement of.

  According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the package includes a plurality of electrical wirings electrically connected to the respective electrodes, the storage recesses on the one surface of the package body. It is characterized in that it is extended from the package body up to the periphery.

  According to the present invention, for example, the electrical wiring can be three-dimensionally formed on the surface of the package body using a plating technique and a laser patterning technique, so that the electrical wiring is formed in a form embedded in the package body. Compared with the case where it does, the freedom degree of design of an electrical wiring can be made high.

  According to an eighth aspect of the present invention, in the first to seventh aspects of the invention, the acceleration sensor chip has the frame portion formed in a rectangular frame shape, and the pads dispersed in four corner portions of the frame portion. It is arranged.

  According to the present invention, it is possible to increase the stress transmission distance from the package body to the gauge resistance, and it is possible to further suppress the output fluctuation of the acceleration sensor chip.

  A ninth aspect of the invention is characterized in that, in the first to eighth aspects of the invention, the conductive adhesive comprises a silicone-based adhesive.

  According to this invention, it is possible to further increase the accuracy of the thickness of the stress relaxation layer by using a silicone resin having a lower viscosity than the epoxy resin as the conductive adhesive.

  The invention of claim 10 is the method of manufacturing an acceleration sensor according to any one of claims 1 to 9, wherein a predetermined amount of a conductive adhesive is dropped on each electrode of the package. Then, each pad of the acceleration sensor chip and each electrode of the package are aligned so that they overlap each other in the thickness direction of the acceleration sensor chip, and each pad and each electrode are electrically connected by mounting the acceleration sensor chip on the package. It is characterized by connecting.

  According to the present invention, there is provided an acceleration sensor capable of suppressing fluctuations in output characteristics due to connection between a pad of an acceleration sensor chip and an electrode of a package and suppressing excessive displacement of a weight portion. be able to.

  According to the first aspect of the present invention, there is an effect that it is possible to suppress fluctuations in output characteristics due to connection between the pads of the acceleration sensor chip and the electrodes of the package, and it is possible to suppress excessive displacement of the weight portion. is there.

  The invention according to claim 10 provides an acceleration sensor capable of suppressing fluctuations in output characteristics associated with connection between a pad of an acceleration sensor chip and an electrode of a package and suppressing excessive displacement of a weight portion. There is an effect that can be done.

(Embodiment 1)
As shown in FIG. 1, the acceleration sensor according to the present embodiment includes an acceleration sensor chip 1 and a package 3 that houses the acceleration sensor chip 1. Hereinafter, the acceleration sensor chip 1 will be described, and then the package 3 will be described.

  As shown in FIGS. 1 and 2, the acceleration sensor chip 1 includes a frame portion 11 having a frame shape (in this embodiment, a rectangular frame shape), and a weight portion 12 disposed inside the frame portion 11 includes an acceleration sensor. On the main surface (lower surface in FIG. 1 (b)) side of the chip 1, it is supported by the frame portion 11 through four flexible strip-shaped bending portions 13 so as to be swingable. Here, the acceleration sensor chip 1 is obtained by processing an SOI wafer having an n-type silicon layer (active layer) on an insulating layer (buried oxide film) made of a silicon oxide film on a support substrate made of a silicon substrate. The frame portion 11 is formed by using an SOI wafer support substrate, an insulating layer, and a silicon layer. On the other hand, the bending portion 13 is formed using a silicon layer in the SOI wafer and is thinner than the frame portion 11. For the SOI wafer, the thickness of the support substrate is set to about 400 to 600 μm, the thickness of the insulating layer is set to about 0.3 to 1.5 μm, and the thickness of the silicon layer is set to about 4 to 6 μm. These numerical values are not particularly limited.

  The weight portion 12 is continuously integrated into each of the rectangular parallelepiped core portion 12a supported by the frame portion 11 via the four flexure portions 13 and the four corners of the core portion 12a when viewed from the main surface side of the acceleration sensor chip 1. And four accompanying portions 12b having a rectangular parallelepiped shape connected to each other. In other words, the weight portion 12 is formed integrally with the core portion 12a and the core portion 12a in which the other end portion of each bending portion 13 whose one end portion is connected to the inner side surface of the frame portion 11 is connected to the outer surface. It has four accompanying parts 12b arranged in the space between the part 12a and the frame part 11. In other words, each associated portion 12b is disposed in a space surrounded by the frame portion 11 and the core portion 12a and the two bent portions 13 and 13 extending in a direction orthogonal to each other when viewed from the main surface side of the acceleration sensor chip 1. In addition, a slit 14 is formed between each of the accompanying portions 12b and the frame portion 11, and the interval between the adjacent accompanying portions 12b with the bending portion 13 interposed therebetween is longer than the width dimension of the bending portion 13. Yes. Here, the core portion 12a is formed using a support substrate, an insulating layer, and a silicon layer of an SOI wafer, and each accompanying portion 12b is formed using a support substrate of the SOI wafer. Thus, on the main surface side of the acceleration sensor chip 1, the surface of each associated portion 12b is separated from the plane including the surface of the core portion 12a toward the other surface of the acceleration sensor chip 1 (upper surface in FIG. 1B). positioned.

  By the way, as shown on the right side of each of FIG. 1A and FIG. 2, the direction along one side of the rectangular frame-shaped frame portion 11 in the plane orthogonal to the thickness direction of the acceleration sensor chip 1 is the x-axis direction. If the direction along the side orthogonal to one side is defined as the y-axis direction and the thickness direction of the acceleration sensor chip 1 is defined as the z-axis direction, the weight portion 12 extends in the x-axis direction and sandwiches the core portion 12a. It is supported by the frame portion 11 via a pair of bending portions 13 and 13 and a pair of bending portions 13 and 13 extending in the y-axis direction and sandwiching the core portion 12a. Here, the acceleration sensor chip 1 has two piezoresistors (not shown) for detecting acceleration in the x-axis direction in the vicinity of the core portion 12a in the two flexures 13 and 13 whose longitudinal direction is the x-axis direction. Two piezoresistors (not shown) for detecting acceleration in the y-axis direction are formed in the vicinity of the core portion 12a of the two flexures 13 and 13, each having a longitudinal direction in the y-axis direction. One piezoresistor (not shown) for detecting acceleration in the z-axis direction is formed in the vicinity of the frame portion 11 in the longitudinal direction of each of the two bent portions 13, and four piezoresistors are provided for each axial direction. Are connected via wiring (diffusion layer wiring, metal wiring, etc.) so as to form a bridge circuit. Further, a protective film (not shown) made of a silicon oxide film is formed on the one surface side of the acceleration sensor chip 1, and the pads 16 serving as the terminals of the bridge circuit are portions corresponding to the frame portion 11. The acceleration sensor chip 1 protrudes from the main surface side. Here, the acceleration sensor chip 1 is provided with the above-described pad 16 only on two sides (two sides along the x-axis direction) of the four sides of the frame portion 11 having a rectangular frame shape.

  Therefore, when acceleration acts on the acceleration sensor chip 1, the weight portion 12 is displaced relative to the frame portion 11 in accordance with the direction and magnitude of the acceleration, and as a result, the bending portion 13 is bent and the resistance of the piezoresistor is increased. The value will change. That is, by detecting a change in the resistance value of the piezoresistor, it is possible to detect accelerations in the x-axis direction, the y-axis direction, and the z-axis direction that act on the acceleration sensor chip 1. In short, if an appropriate power source for detection is connected between one terminal at the diagonal position of each bridge circuit, a voltage between the other terminal at the diagonal position is detected, and appropriate correction is applied, the weight 12 is affected. A voltage proportional to the acceleration in each of the x-axis direction, the y-axis direction, and the z-axis direction can be obtained. In the present embodiment, each piezoresistor constitutes a gauge resistor whose resistivity changes due to strain generated in the flexure 13 due to the displacement of the weight 12 relative to the frame 11.

  Next, the package 3 will be described.

  The package 3 includes a package body 31 made of ceramic. The package body 31 is formed with a housing recess 32 for housing the acceleration sensor chip 1 on one surface, and the main surface of the acceleration sensor chip 1 serves as the inner bottom surface 32a of the housing recess 32. The acceleration sensor chip 1 is housed in a form facing the. The package 3 is provided between the inner bottom surface 32 a of the storage recess 32 a in the package body 31 and the main surface of the acceleration sensor chip 1 and is electrically connected to each of the plurality of pads 16 of the acceleration sensor chip 1. An electrode 33 is provided. Here, each electrode 33 is formed on the inner bottom surface 32 a of the housing recess 32 in the package body 31, and is connected to an external connection terminal (not shown) exposed outside the package body 31 and the package body 31. They are electrically connected via embedded electrical wiring (not shown). The package 3 includes a rectangular plate-shaped package lid (not shown) that closes the one surface of the package body 31. Here, the outer peripheral shape of the package body 31 is a rectangular shape, and the package lid is hermetically sealed with an adhesive to the package body 3, and the back surface of the acceleration sensor chip 1 (in FIG. 1B). On the upper surface side, a space (a swinging space of the weight portion 12) that allows the weight portion 12 to be displaced is formed between the weight portion 12 and the package lid.

  Further, in the acceleration sensor chip 1, the pad 16 and the electrode 33 facing each other in the thickness direction of the acceleration sensor chip 1 are electrically connected via the stress relaxation layer 4 made of a conductive adhesive such as silicone resin or epoxy resin. It is connected to the. In this embodiment, in the thickness direction of the acceleration sensor chip 1, a space (the weight portion 12) in which the weight portion 12 can be displaced between the inner bottom surface 32 a of the housing recess 32 of the package body 31 and the acceleration sensor chip 1. Of the pad 16, the stress relaxation layer 4, and the electrode 33 that overlap in the thickness direction of the acceleration sensor chip 1 so that the package body 31 functions as a stopper that restricts excessive displacement of the weight portion 12. The total thickness (the total thickness of the pad 16, the stress relaxation layer 4, and the electrode 33) is set. In short, by electrically connecting each pad 16 of the acceleration sensor chip 1 and each electrode 33 of the package 3 via the stress relaxation layer 4, the inner bottom surface 32a of the housing recess 32 of the package body 31 and the acceleration sensor chip. A space allowing displacement of the weight portion 12 with respect to 1 is formed, and the core portion 12a of the weight portion 12 of the acceleration sensor chip 1 and the housing recess of the package body 31 in a state in which no acceleration is applied to the acceleration sensor chip 1 The gap length between the inner bottom surface 32a of 32 and the thickness of the acceleration sensor chip 1 in the thickness direction is substantially equal to the sum of the thickness of the pad 16, the thickness of the electrode 33, and the thickness of the stress relaxation layer 4. In addition, it becomes possible to raise the precision of the thickness of the stress relaxation layer 4 more by using a silicone-type resin whose viscosity is lower than an epoxy-type resin as a conductive adhesive.

  In manufacturing the acceleration sensor described above, a predetermined amount (fixed amount) of conductive adhesive is dropped on each electrode 33 of the package 3, and then each pad 16 of the acceleration sensor chip 1 and each electrode of the package 3. The acceleration sensor chip 1 may be mounted on the package 3 so as to be overlapped with each other in the thickness direction of the acceleration sensor chip 1 (in this case, the inside of the storage recess 32 of the acceleration sensor chip 1 and the package body 31). Each pair of the pad 16 and the electrode 33 overlapping in the thickness direction by bringing the bottom surface 32a close to each other may be electrically connected via the stress relaxation layer 4 made of a conductive adhesive).

  Thus, in the acceleration sensor of the present embodiment, the pad 16 of the acceleration sensor chip 1 and the electrode 33 of the package 3 can be electrically connected without using a bonding wire, and the pad 16 and the electrode 33 can be electrically connected. Since the stress relaxation layer 4 made of a conductive adhesive is interposed between them, it is difficult for stress to be transmitted from the package body 31 to the acceleration sensor chip 1, so that the pad 16 of the acceleration sensor chip 1 and the electrode 33 of the package 3 are connected. Along with this, it is possible to prevent stress from being generated in the frame portion 11 and to suppress fluctuations in output characteristics.

  Further, in the acceleration sensor of the present embodiment, a space in which the weight 12 can be displaced is formed between the inner bottom surface 32 a of the housing recess 32 of the package body 31 and the acceleration sensor chip 1 in the thickness direction of the acceleration sensor chip 1. And the sum of the thicknesses of the pad 16, the stress relaxation layer 4 and the electrode 33 that overlap in the thickness direction of the acceleration sensor chip 1 is set so that the package body 31 functions as a stopper that restricts excessive displacement of the weight portion 12. Therefore, the package main body 31 has a function as a stopper for restricting excessive displacement of the weight portion 12, and it is possible to suppress excessive displacement of the weight portion 12.

(Embodiment 2)
The basic configuration of the acceleration sensor according to the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 4, the stress relaxation layer 4 side is formed on each pad 16 in the frame portion 11 of the acceleration sensor chip 1. The convex part 19 which protrudes to the stress relaxation layer 4 side is formed in the formation part of each electrode 33 in the inner bottom face 32a of the storage recess 32 of the package body 31. Is different. Since other configurations are the same as those of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  Thus, in the acceleration sensor of the present embodiment, the distance between the core portion 12a of the weight portion 12 and the inner bottom surface 32a of the housing recess 32 of the package body 31 is determined by the thickness of the pad 16 and the thickness of the stress relaxation layer 4. Since the sum of the thickness of the electrode 33 and the thickness of each of the convex portions 16 and 32 b is substantially equal, the acceleration sensor chip 1 is interposed between the weight portion 12 and the inner bottom surface 32 a of the housing recess 32 of the package body 31. It is possible to easily secure a space having a gap length corresponding to the allowable displacement amount of the weight portion 12 in the thickness direction. In the acceleration sensor of this embodiment, the thickness of the stress relaxation layer 4 can be made relatively thin as compared with the acceleration sensor of Embodiment 1, and the conductive adhesive used as the stress relaxation layer 4 is the acceleration sensor chip 1. It is possible to prevent a short circuit between adjacent pads 16 protruding from between the pad 16 and the electrode 33 overlapping in the thickness direction.

  In the present embodiment, the protrusions 19 projecting toward the stress relaxation layer 4 are formed at the respective portions of the pads 16 in the frame portion 11 of the acceleration sensor chip 1, and the inside of the storage recess 32 of the package body 31. Although the convex part 32b which protrudes to the stress relaxation layer 4 side is formed in the formation part of each electrode 33 in the bottom face 32a, it is not necessary to form a convex part in both the acceleration sensor chip 1 and the package main body 31. A convex portion may be formed on at least one side.

(Embodiment 3)
The basic configuration of the acceleration sensor of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 5, each of the stress relaxation layers 4 is a spherical agglomerate 42 made of a conductive material (for example, silver). Is different. Here, in this embodiment, the particle size of the agglomerates 42 and the thickness of the stress relaxation layer 4 are set equal. Since other configurations are the same as those of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  Therefore, in the acceleration sensor of the present embodiment, the allowable displacement of the weight portion 12 in the thickness direction of the acceleration sensor chip 1 is between the core portion 12a of the weight portion 12 and the inner bottom surface 32a of the housing recess 32 of the package body 31. It becomes possible to easily secure a space with a gap length according to the amount, and to improve the accuracy of the gap length.

  In the present embodiment, since the particle size of the agglomerates 42 and the thickness of the stress relaxation layer 4 are set to be equal, the gap between the pad 16 and the electrode 33 of the package 3 that overlap in the thickness direction of the acceleration sensor chip 1 is set. The distance can be made uniform, and the occurrence of distortion in the frame portion 11 due to the variation in the thickness of the stress relaxation layer 4 can be suppressed. In addition, in the acceleration sensor according to another embodiment, the stress relieving layer 4 may contain the agglomerates 42.

(Embodiment 4)
The basic configuration of the acceleration sensor of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 6, each electrode 33 of the package 3 is formed in a strip shape, and from the inner bottom surface of the package body 31. The difference is that they are spaced apart from each other by a predetermined distance and are supported by the package body 31 and have flexibility in the thickness direction of the acceleration sensor chip 1. Here, each electrode 33 is arranged so that the thickness direction thereof coincides with that of the acceleration sensor chip 1. Since other configurations are the same as those of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  Therefore, in the acceleration sensor of the present embodiment, the amount of allowable displacement of the weight portion 12 in the thickness direction of the acceleration sensor chip 1 is determined between the weight portion 12 and the inner bottom surface 32a of the housing recess 32 of the package body 31. It becomes possible to secure the space of the gap length more easily. In the present embodiment, each electrode 33 of the package 3 is flexible in the thickness direction of the acceleration sensor chip 1, so that a mounting board (for example, a circuit board such as a glass epoxy board) on which the package 3 is mounted. It is possible to reduce the influence of the stress generated in the package body 31 due to the difference in thermal expansion coefficient between the package body 31 and the package body 31 on the acceleration sensor chip 1.

(Embodiment 5)
By the way, in the acceleration sensors of the first to fourth embodiments, the acceleration sensor chip 1 is housed in the package body 31 with the main surface facing the inner bottom surface 32a of the housing recess 32 of the package body 31. In the acceleration sensor according to the embodiment, as shown in FIG. 7, the acceleration sensor chip 1 is housed in the package body 31 such that the back surface thereof faces the inner bottom surface 32 a of the housing recess 32 of the package body 31. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In the acceleration sensor of the present embodiment, the acceleration sensor chip 1 is provided on the back surface of the acceleration sensor chip 1 and a plurality of through wirings 17 that are electrically connected to the pads 16 on the main surface side and penetrated in the thickness direction. A plurality of back surface pads 18 electrically connected to the respective through wirings 17, and the back surface pad 18 and the electrode 33 which overlap in the thickness direction of the acceleration sensor chip 1 are made of stress relaxation. They are electrically connected via the layer 4.

  In manufacturing the acceleration sensor described above, a predetermined amount (fixed amount) of conductive adhesive is dropped on each electrode 33 of the package 3, and then each pad 16 of the acceleration sensor chip 1 and each electrode of the package 3. The acceleration sensor chip 1 may be mounted on the package 3 so as to be overlapped with each other in the thickness direction of the acceleration sensor chip 1 (in this case, the inside of the storage recess 32 of the acceleration sensor chip 1 and the package body 31). Each pair of the back surface pad 18 and the electrode 33 that overlap in the thickness direction by bringing the bottom surface 32a close to each other may be electrically connected via the stress relaxation layer 4 made of a conductive adhesive). In the present embodiment, the back surface pad 18 provided on the back surface side of the acceleration sensor chip 1 is arranged at a position overlapping with the pad 16 provided on the main surface side of the acceleration sensor chip 1 in the thickness direction. 1 and package 3 can be easily aligned.

  Thus, in the acceleration sensor of the present embodiment, the pad 16 on the main surface side of the acceleration sensor chip 1 and the electrode 33 of the package 3 are electrically connected through the through wiring 17, the back surface pad 18, and the stress relaxation layer 4. Therefore, the pad 16 of the acceleration sensor chip 1 and the electrode 33 of the package 3 can be electrically connected without using a bonding wire, and conductive bonding is performed between the back surface pad 18 and the electrode 33. Since a stress relaxation layer made of an agent is interposed and stress is hardly transmitted from the package body 31 to the acceleration sensor chip 1, stress is applied to the frame portion 11 due to the connection between the pad 16 of the acceleration sensor chip 1 and the electrode 33 of the package 3. Can be prevented and fluctuations in output characteristics can be suppressed.

  In the acceleration sensor of the present embodiment, the back surface that overlaps in the thickness direction of the acceleration sensor chip 1 between the inner bottom surface 32a of the housing recess 32 of the package body 31 and the acceleration sensor chip 1 in the thickness direction of the acceleration sensor chip 1. Since a space having a gap length corresponding to the total thickness of the pad 18, the stress relaxation layer 4, and the electrode 33 (the total thickness of the back pad 18, the stress relaxation layer 4, and the electrode 33) is formed. The package body 31 functions as a stopper that restricts the excessive displacement of the weight portion 12, and the excessive displacement of the weight portion 12 can be suppressed.

(Embodiment 6)
The basic configuration of the acceleration sensor of this embodiment is substantially the same as that of the fifth embodiment, and is different in that the package 3 includes electrical wiring 38 exposed on the surface of the package body 31 as shown in FIG. . Here, each electrical wiring 38 is electrically connected to each electrode 33 and extends in a form exposed from the package body 31 to the periphery of the storage recess 32 on the one surface of the package body 31. An end portion on the opposite side to each electrode 33 side (in the illustrated example, a portion formed on the peripheral portion of the housing recess 32 on the one surface of the package body 31) constitutes a terminal for external connection. Since the other configuration is the same as that of the fifth embodiment, the same components as those of the fifth embodiment are denoted by the same reference numerals and description thereof is omitted.

  Thus, in the acceleration sensor of the present embodiment, the electrical wiring 38 can be three-dimensionally formed on the surface of the package body 31 by using, for example, a plating technique and a laser patterning technique at the time of manufacture. The degree of freedom in designing the electrical wiring 38 can be increased as compared with the case where the wiring is formed so as to be embedded in the package body 31.

(Embodiment 7)
The basic configuration of the acceleration sensor of the present embodiment is substantially the same as that of the sixth embodiment, and a plurality of pads 16 are distributed and arranged at four corners of the frame portion 11 as shown in FIG. Is different. Since the other configuration is the same as that of the sixth embodiment, the same components as those of the sixth embodiment are denoted by the same reference numerals and description thereof is omitted.

  Thus, in the acceleration sensor according to the present embodiment, the four corners of the frame portion 11 of the acceleration sensor chip 1 are fixed to the package 3 via the stress relaxation layer 4. It becomes possible to lengthen the stress transmission distance to the gauge resistance formed in the bending part 13, and it becomes possible to suppress the output fluctuation of the acceleration sensor chip 1 more.

  In each of the above-described embodiments, the acceleration sensor chip 1 formed using an SOI wafer is exemplified. However, the acceleration sensor chip 1 is not limited to the SOI wafer, and may be formed using, for example, a silicon substrate. Further, the gauge resistance provided in the bending portion 13 is not limited to the piezoresistance, and for example, carbon nanotubes may be employed.

Embodiment 1 is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ of (a), (c) is a schematic cross-sectional view along BB ′ of (a), and (d) is a schematic cross-sectional view of (a). It is CC 'schematic sectional drawing of (a). It is a schematic plan view of the acceleration sensor chip in the same as the above. It is a schematic plan view of the package same as the above. Embodiment 2 is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ of (a), (c) is a schematic cross-sectional view along BB ′ of (a), and (d) is It is CC 'schematic sectional drawing of (a). Embodiment 3 is shown, wherein (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ of (a), (c) is a schematic cross-sectional view along BB ′ of (a), and (d) is It is CC 'schematic sectional drawing of (a). Embodiment 4 is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ in (a), (c) is a schematic cross-sectional view along BB ′ in (a), and (d) is It is CC 'schematic sectional drawing of (a). Embodiment 5 is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ in (a), (c) is a schematic cross-sectional view along BB ′ in (a), and (d) is It is CC 'schematic sectional drawing of (a). Embodiment 6 is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ in (a), (c) is a schematic cross-sectional view along BB ′ in (a), and (d) is It is CC 'schematic sectional drawing of (a). Embodiment 7 is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ in (a), (c) is a schematic cross-sectional view along BB ′ in (a), and (d) is It is CC 'schematic sectional drawing of (a). A conventional example is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view along AA ′ of (a), (c) is a schematic cross-sectional view along BB ′ of (a), and (d) is ( It is CC 'schematic sectional drawing of a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Acceleration sensor chip 3 Package 4 Stress relaxation layer 11 Frame part 12 Weight part 13 Deflection part 14 Slit 16 Pad 31 Package main body 32 Storage recess 32a Inner bottom face 33 Electrode

Claims (10)

  A weight part disposed inside the frame-like frame part is supported by the frame part through four flexible parts extending in four directions from the weight part so as to be swingable, and electrically connected to a gauge resistance provided in the flexible part. An acceleration sensor chip having a plurality of connected pads projecting from the frame on the main surface side, a package body in which a storage recess for storing the acceleration sensor chip is formed on one surface, and an inner bottom surface of the storage recess in the package body And a package having a plurality of electrodes provided between the main surface of the acceleration sensor chip facing the inner bottom surface and electrically connected to each of the plurality of pads of the acceleration sensor chip, in the thickness direction of the acceleration sensor chip Opposite pads and electrodes are electrically connected via a stress relaxation layer made of a conductive adhesive, and the package body storage recess in the thickness direction. A pad and a stress relieving layer that overlap in the thickness direction so that a space is formed between the inner bottom surface and the acceleration sensor chip so that the weight can be displaced, and the package body functions as a stopper that restricts excessive displacement of the weight. An acceleration sensor characterized in that the total thickness of the electrode and the electrode is set.   Protrusions projecting toward the stress relieving layer are formed on at least one of the pad forming part of the frame part and the electrode forming part of the inner bottom surface of the housing recess of the package body. The acceleration sensor according to claim 1.   The acceleration sensor according to claim 1, wherein the stress relaxation layer contains agglomerates.   The acceleration sensor according to claim 3, wherein the agglomerate is made of a conductive material, and the grain size of the agglomerate and the thickness of the stress relaxation layer are set to be equal.   5. The electrode according to claim 1, wherein the electrode is disposed at a predetermined distance from an inner bottom surface of the package body, is supported by the package body, and has flexibility in the thickness direction. The acceleration sensor in any one.   A weight part disposed inside the frame-like frame part is supported by the frame part through four flexible parts extending in four directions from the weight part so as to be swingable, and electrically connected to a gauge resistance provided in the flexible part. An acceleration sensor chip having a plurality of connected pads projecting from the frame on the main surface side, a package body in which a storage recess for storing the acceleration sensor chip is formed on one surface, and an inner bottom surface of the storage recess in the package body And a package having a plurality of electrodes that are electrically connected to each of the plurality of pads of the acceleration sensor chip, the acceleration sensor chip including each of the pads. A plurality of through wirings that are electrically connected to each other in the thickness direction and electrically connected to each through wiring provided on the back surface of the acceleration sensor chip. A plurality of and a backside pad, an acceleration sensor, characterized by comprising electrically connected through the stress relieving layer and the back pad and electrode overlapping in the thickness direction is made of a conductive adhesive agent.   In the package, a plurality of electrical wirings electrically connected to the respective electrodes are extended so as to be exposed from the package body to the periphery of the storage recess on the one surface of the package body. The acceleration sensor according to any one of claims 1 to 6, characterized in that:   8. The acceleration sensor chip according to claim 1, wherein the frame portion is formed in a rectangular frame shape, and the pads are distributed and arranged at four corners of the frame portion. Acceleration sensor according to the above.   The acceleration sensor according to claim 1, wherein the conductive adhesive is made of a silicone-based adhesive.   10. The acceleration sensor manufacturing method according to claim 1, wherein a predetermined amount of a conductive adhesive is dropped on each electrode of the package, and then each of the acceleration sensor chips. The pad and each electrode of the package are aligned so as to overlap each other in the thickness direction of the acceleration sensor chip, and each pad and each electrode are electrically connected by mounting the acceleration sensor chip on the package. A method for manufacturing an acceleration sensor.

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