JP2006128431A - Sensor package and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small, and reliable sensor package, and to provide a method for easily manufacturing the sensor package. <P>SOLUTION: The sensor package comprises a sensor; and a protective material fixed to a sensor surface while the protective material opposes the active surface of the surface of the sensor via a void. The sensor has a plurality of terminals in the outside region of the active surface of the surface, and a plurality of wires on the back. Each wire has an external terminal and an external terminal projecting member arranged at the external terminal. The protective material has a plurality of lead wires in the outside region on the active surface of a sensor. Each lead wire is connected to the terminal of the sensor via a bump, and connected to the wire on the back of the sensor via the wire. The wire, and connection parts between the wire and wiring, and the wire and the lead wire are covered with a sealing member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sensor package, and more particularly to a sensor package having a protective material on the active surface side of a sensor and a method for easily manufacturing the sensor package.

Conventionally, image sensors such as CCD and CMOS, and sensors such as acceleration sensors have been used for various purposes. For example, in an image sensor, one surface of a semiconductor chip is an active surface on which a light receiving element that performs photoelectric conversion is disposed. Such a sensor is mounted on a wiring board or the like, and connected to the wiring board via connection means such as wire bonding in order to output a signal from the sensor to a signal processing system. An image sensor or the like is configured by providing and sealing a protective material, for example, an infrared cut filter, so as to be provided (Patent Document 1).
JP-A-8-88339

However, conventional image sensors tend to cause contamination of the active surface of the sensor in a series of manufacturing processes such as individual sensor mounting, wire bonding, and subsequent sealing processes, which hinders yield improvement. It was.
Further, since wire bonding is performed when individual sensors are mounted on a wiring board, it is necessary to expand in the surface direction, and there is a limit to miniaturization, and there is a limit to the efficiency of manufacturing.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a small and highly reliable sensor package and a manufacturing method for easily manufacturing such a sensor package. .

  In order to achieve such an object, the sensor package of the present invention includes a sensor and a protective material fixed to the sensor surface so as to face the active surface of the sensor surface via a gap. The sensor has a plurality of terminals in the outer region of the active surface on the front surface, a plurality of wirings on the back surface, and external terminals are connected to the respective wirings, and external terminal convex members are connected to the external terminals. The protective material has a plurality of lead wires in an outer region of the active surface of the sensor, each lead wire is connected to the sensor terminal via a bump, and a wire Connected to the wiring on the back surface of the sensor, and the connection portion of the wire and the wire and the wiring or the lead-out wiring is covered with a sealing member; It was.

As another aspect of the present invention, the protective material is an infrared cut filter.
As another aspect of the present invention, a stress relaxation conductive layer is interposed between the external terminal and the external terminal convex member.
As another aspect of the present invention, the stress relaxation conductive layer is configured such that conductive particles are dispersed in a synthetic rubber.

The method for manufacturing a sensor package according to the present invention includes a step of partitioning a wafer into multiple impositions, producing a sensor for each imposition, and insulating a surface on the opposite side of the surface where the active surface of the sensor is present. A step of forming a layer, a step of forming a plurality of wirings and external terminals connected to the wiring for each imposition, and a desired location of the wiring and the external terminals for each imposition. Forming an insulating pattern so as to be exposed, dicing the wafer with multiple impositions to produce a sensor chip, and forming a plurality of lead wires for each imposition of the protective material partitioned into multiple impositions In addition, the sensor chip is fixed for each imposition so that the active surface faces the protective material via a gap, and the sensor chip terminal is connected to the lead-out wiring via a bump. A step of connecting the lead-out wiring and the wiring of the sensor chip with a wire for each imposition, and covering the wire and a connection portion between the wire and the wiring and the lead-out wiring with a sealing member And a step of dicing the protective material having multiple faces and a step of forming an external terminal convex member on the external terminal either before or after the step of dicing the protective material.
As another aspect of the present invention, a stress relaxation conductive layer is formed on the external terminal, and the external terminal convex member is formed on the stress relaxation conductive layer.

Since such a sensor package of the present invention includes the external terminal convex member, it is easy to mount on the wiring board, wire bonding at the time of mounting is unnecessary, and the spread in the surface direction is suppressed, The apparatus can be miniaturized and the manufacturing efficiency can be increased. In addition, when the active surface of the sensor is prevented from being contaminated by the protective material, and the sensor package is contaminated during the mounting process, the sensor package in a good state can be obtained simply by cleaning the protective material surface, and the production yield can be obtained. Will improve.
In the manufacturing method of the sensor package of the present invention, it is possible to perform sensor assembly at the wafer level and collective assembly for fixing the protective material and the sensor with multiple attachments, and then dicing to obtain the sensor package. Assembling at the individual sensor package level is unnecessary, process management is easy, and manufacturing costs can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
[Sensor package]
FIG. 1 is a front view showing an embodiment of a sensor package of the present invention, FIG. 2 is a rear view, and FIG. 3 is a schematic cross-sectional view taken along line AA shown in FIGS. 1 to 3, the sensor package 1 of the present invention includes a sensor 11 and a protective material 21 fixed to the surface 11 a of the sensor 11 by a sealing rib 19. FIG. 1 shows a state in which the protective material 21 shown in FIG. 3 is removed, and an active surface 12 of the sensor 11 described later is hatched.

  The sensor 11 constituting the sensor package 1 of the present invention has an active surface 12 on the surface 11a, and includes a plurality of terminals 13 in a region outside the active surface 12. The sensor 11 is not particularly limited, and may be an image sensor such as a CCD or CMOS, or various MEMS (Micro Electromechanical System) sensors such as an acceleration sensor, a pressure sensor, or a gyro sensor. The active surface 12 means a region that exhibits a desired detection function of the sensor, such as a region where light receiving elements that perform photoelectric conversion are arranged to form a plurality of pixels.

  In addition, the sensor 11 includes a plurality of wirings 15 on the back surface 11 b via the insulating layer 14, and external terminals 16 are connected to the respective wirings 15. Further, a desired portion of the wiring 15 to be connected to the wire 25 described later and the external terminal 16 are exposed so as to straddle each wiring 15 and the external terminal 16 (in the example shown in FIG. 2, (Corridor shape) An insulating layer 20 is provided. Each external terminal 16 is provided with an external terminal convex member 17 through a stress relaxation conductive layer 18a, a conductive layer 18b, and barrier metal layers 18c and 18d.

  The protective material 21 constituting the sensor package 1 of the present invention includes a plurality of lead wires 22 in a region facing the outer region of the active surface 12 in the surface 21 a facing the sensor 11, and each lead wire 22 is a bump 23. Is connected to the terminal 13 of the sensor 11. Further, the outer part of each lead-out wiring 22 is connected to each wiring 15 of the sensor 11 through a wire 25. The wire 25, the wiring 15, and the lead-out wiring 22 are covered with a sealing member 27. In addition, the active surface 12 of the sensor 11 faces the protective material 21 via the gap 5, and the gap 5 is sealed by a sealing rib 19 shown in a gallery shape in FIG. 1.

The insulating layer 14 disposed so as to cover the back surface 11b of the sensor 11 and the insulating layer 20 disposed so as to straddle each wiring 15 and the external terminal 16 are, for example, silicon dioxide, silicon nitride, It can be an inorganic material of titanium nitride, or an organic material such as polybenzoxazole resin, epoxy resin, benzocyclobutene resin, cardo resin, or polyimide resin.
Further, the material of the wiring layer 15 and the external terminal 16 disposed on the back surface 11b of the sensor 11 can be a conductive material such as Cu, Ag, Au, Sn, and the Cu layer 15a as shown in the illustrated example. A three-layer structure of Ni layer 15b and Au layer 15c may be used. In the case of such a laminated structure, the material of each layer and the number of laminated layers can be appropriately set.

The external terminal convex member 17 disposed on the external terminal 16 is for mounting the sensor package 1 on a wiring board or the like, and may be made of a material such as solder, Au, or Ag. Although the shape and dimensions of the external terminal convex member 17 are not particularly limited, for example, the height can be set in the range of 70 to 150 μm.
The stress relaxation conductive layer 18a interposed between the external terminal 16 and the external terminal convex member 17 has the stress due to the difference in thermal contraction between the sensor package 1 mounted on the wiring board and the wiring board and the external terminal convex member 17. This is intended to prevent damage due to concentration. Such a stress relaxation conductive layer 18a can be formed by dispersing conductive particles in, for example, synthetic rubber, resin, or the like. Specifically, it can be formed using a silicone Ag paste, an epoxy Ag paste, a urethane Ag paste, or the like. The thickness of the stress relaxation conductive layer 18a can be appropriately set according to the material to be used, the area, and the like, and can be set in the range of 10 to 50 μm, for example.

  For the conductive layer 18b interposed between the external terminal 16 and the external terminal convex member 17, for example, Cu can be used. The barrier metal layers 18c and 18d can be, for example, a combination of a Ni layer and an Au layer, a combination of a Ni layer, a Pd layer, and an Au layer. In the present invention, the barrier metal layer may not be interposed.

  For example, a material such as glass, polyimide, or polycarbonate can be used for the protective material 21 described above, and a material having an infrared absorption function may be used as an infrared cut filter. The thickness of the protective material 21 can be set, for example, in the range of 300 to 1000 μm in consideration of the material, light transmittance, and the like. In addition, the thickness of the gap 5 existing between the protective material 21 and the active surface 12 of the sensor 11 can be set in the range of 1 to 20 μm, for example.

The sealing rib 19 and the sealing member 27 for fixing the protective material 21 as described above to the surface 11a of the sensor 11 via the predetermined gap 5 are, for example, silicone resin, epoxy resin, acrylic resin Etc. can be used.
The material of the lead-out wiring 22 included in the protective material 21 can be a conductive material such as Cu, Ag, Au, or Sn.

The material of the bump 23 that connects each lead-out wiring 22 and the terminal 13 of the sensor 11 can also be a conductive material such as Cu, Ag, Au, or Sn.
In addition, the number, position, etc. of the terminal 13, the wiring 15, the external terminal 16, the external terminal convex member 17, and the lead-out wiring 22 in the sensor package 1 described above can be arbitrarily set without being limited to the illustrated example.

  Since the sensor package 1 of the present invention as described above is provided with the external terminal convex member 17, it is easy to mount on the wiring board, and wire bonding at the time of mounting is unnecessary, and the spread in the surface direction is increased. Therefore, the apparatus can be reduced in size, and the manufacturing efficiency can be improved. Further, when the protective surface 21 prevents contamination of the active surface 12 of the sensor 11 and the sensor package 1 is contaminated during the mounting process or the like, the sensor package 1 in a good state can be obtained simply by cleaning the protective material 21. As a result, the manufacturing yield is improved.

The sensor package of the present invention is not limited to the above-described embodiment. For example, a configuration in which a notch is provided in the center of the external terminal 16 and the stress relaxation conductive layer 18 a is fixed to the insulating layer 14 together with the external terminal 16 may be employed. By setting it as such a structure, the adhesiveness of the stress relaxation conductive layer 18a can be made higher.
In addition, the external electrode convex member 17 may be disposed by interposing only the barrier metal layers 18c and 18d without interposing the stress relaxation conductive layer 18a and the conductive layer 18b.
Further, the external terminal 16 and the external electrode convex member 17 are not provided with the stress relaxation conductive layer 18a, the conductive layer 18b, and the barrier metal layers 18c and 18d, but instead are Ti thin film layer, Ni thin film layer, Au thin film layer, or the like. The external electrode convex member 17 may be disposed through a material capable of improving the adhesion with the external electrode. Further, a conductive layer such as Cu, Ni, or Au may be interposed between the titanium thin film layer and the external electrode convex member 17.

[Method for manufacturing sensor package]
Next, the manufacturing method of the sensor package of this invention is demonstrated.
4 to 6 are process diagrams showing an embodiment of the sensor package manufacturing method of the present invention, taking the sensor package 1 shown in FIGS. 1 to 3 as an example.
First, the silicon wafer 31 is partitioned into multiple impositions, and the sensor 11 is produced for each imposition 31A (FIG. 4A). The sensor 11 is manufactured using, for example, a MEMS (Micro Electromechanical System) method. The produced sensor 11 has an active surface 12 on the surface and a plurality of terminals 13 in a region outside the active surface 12.

Next, an insulating layer 14 is formed on the back surface of the silicon wafer 31 (FIG. 4B), and then, for each imposition 31A, a desired plurality of wirings 15 on the insulating layer 14 and the wirings 15 are connected. External terminals 16 are formed (FIG. 4C).
The insulating layer 14 can be a silicon dioxide film, a silicon nitride film, a titanium nitride film, or the like formed by a vacuum film forming method such as a plasma CVD method, a coating method using a silicon oxide precursor solution, or the like. In addition, for example, a photocurable polybenzoxazole resin, epoxy resin, benzocyclobutene resin, cardo resin, polyimide resin, or the like is applied to the back surface of the silicon wafer 31 and then subjected to a curing process to form the insulating layer 14. can do.

Further, the method for forming the wiring 15 and the external terminal 16 is not particularly limited. For example, a base conductive thin film such as a Cu thin film or a Ti thin film is formed by a vacuum film forming method such as a plasma CVD method or electroless plating. After forming a resist pattern having an opening of a desired wiring shape on the conductive thin film, a conductive material is deposited by electrolytic plating using the underlying conductive thin film as a power feeding layer to form a wiring pattern, and then the resist pattern and the exposed pattern are exposed. Wiring 15 and external terminal 16 can be formed by removing the underlying conductive thin film.
Next, an insulating layer 20 is formed so as to straddle each wiring 15 and the external terminal 16 so as to expose a desired portion of the wiring 15 to be connected to the wire 25 and the external terminal 16 (FIG. 4 ( D)). The insulating layer 20 is formed by applying or laminating a photosensitive polybenzoxazole resin, an epoxy resin, a benzocyclobutene resin, a cardo resin, a polyimide resin, or the like so as to cover the wiring 15 and the external terminal 16, and a desired photomask. The film can be formed by exposing to light and developing.

  Next, a conductive paste (silicone Ag paste, epoxy Ag paste, urethane Ag paste, etc.) having stress relaxation properties is applied on the exposed external terminals 16 by screen printing or the like to form the stress relaxation conductive layer 18a. Then, a conductive layer 18b is formed on the stress relaxation conductive layer 18a by electrolytic plating, and barrier metal layers 18c and 18d are formed so as to cover the conductive layer 18b. The barrier metal layers 18c and 18d can be formed by an electrolytic plating method, a vacuum film forming method, or the like. Further, for each imposition 31A, a sealing rib 19 is provided so as to surround the outside of the active surface 12, and a connection bump 23 is disposed on the terminal 13 of the sensor 11 (FIG. 5A). The sealing rib 19 can be formed by screen printing using, for example, a silicone resin, an epoxy resin, an acrylic resin, or the like.

  Next, the multi-sided silicon wafer 31 is diced to produce a sensor chip 11 ′, and each obtained sensor chip 11 ′ is fixed on the protective material 41. The protective material 41 is divided into multiple impositions, and the lead-out wiring 22 is formed for each imposition 41A. The sensor chip 11 'is fixed to the protective material 41 via the sealing rib 19, and at the same time bumps 23 is connected to the lead wiring 22 (FIG. 5B). Then, the wiring 15 of the sensor chip 11 ′ and the lead-out wiring 22 of the protective material 41 are electrically connected by the wire 25 (FIG. 5C).

  Next, a sealing material is filled between the sensor chips 11 ′ by pouring or the like to form a sealing member 27 that covers the wire 25, the wiring 15, and the lead-out wiring 22 (FIG. 6A). As the sealing material, silicone resin, epoxy resin, acrylic resin, or the like can be used. When the sealing member 27 is formed, the sealing rib 19 prevents the sealing material from entering the gap portion 5 where the active surface 12 and the protective material 41 face each other. However, the pouring amount of the sealing material is adjusted so that the sealing material does not get over the insulating layer 20 where the external terminals 16 are exposed.

Next, the external terminal convex member 17 is formed through the stress relaxation conductive layer 18a, the conductive layer 18b, and the barrier metal layers 18c and 18d provided on the external terminal 16 (FIG. 6B). The external terminal convex member 17 can be formed by, for example, a method of performing reflow after performing paste printing, ball mounting, electrolysis or electroless plating.
Next, the sensor package 1 is obtained by dicing the multi-sided protective material 41 (FIG. 6C).

The sensor package manufacturing method of the present invention as described above can perform sensor assembly at the wafer level and batch assembly for fixing to a protective material with multiple attachments, and then dicing to obtain the sensor package. Assembling at the individual sensor package level is unnecessary, process management is easy, and manufacturing costs can be reduced.
In addition, the manufacturing method of the sensor package of the above-mentioned this invention is an illustration, and this invention is not limited to these embodiment. For example, the external terminal convex member 17 may be formed before the sealing member 27 is formed or after the protective material 41 is diced.

Next, the present invention will be described in more detail with specific examples.
First, a silicon wafer having a thickness of 625 μm was prepared, and was divided into multiple faces with a square having a side of 5 mm. The thermal expansion coefficient of the above silicon wafer in the XY direction (a plane parallel to the surface of the silicon wafer) was 3 ppm.
Next, a sensor (active surface dimension: 4000 μm × 4000 μm) was prepared for each imposition of the silicon wafer by a conventional method, and then back grinding was performed from the back surface of the silicon wafer to a thickness of 200 μm. Each sensor had 20 terminals (5 on each side) around the active surface.

Next, a photosensitive solder resist containing a polybenzoxazole resin (CRC-8600, manufactured by Sumitomo Bakelite Co., Ltd.) is applied to the surface opposite to the active surface of the sensor, and is exposed and cured to form an insulating layer ( A thickness of 8 μm) was formed.
Next, a base conductive thin film made of a Cu thin film (thickness 0.4 μm) was formed on the insulating layer by electroless plating. Next, a dry film resist (APR manufactured by Asahi Kasei Co., Ltd.) was laminated on the underlying conductive thin film. Next, the resist pattern (thickness 20 μm) was formed by exposure and development through a photomask for forming wiring and external terminals. Using this resist pattern as a mask, the above-mentioned underlying conductive thin film as a power feeding layer, electrolytic Cu plating, electrolytic Ni plating, and electrolytic Au plating are sequentially performed to obtain a Cu layer (thickness 10 μm), Ni layer (thickness 2 μm), and Au layer. A plurality of wirings and external terminals (diameter 500 μm) were formed by stacking (thickness 0.2 μm). Five of these wirings and external terminals were formed on one side of each imposition.

Next, the resist pattern and the underlying conductive thin film are removed, and then a solder resist dry film (PFR800AUS402 manufactured by Taiyo Ink Manufacturing Co., Ltd.) is laminated so as to cover the wiring and external terminals, and exposed through a desired mask. By developing, an insulating layer in which only a desired portion of the external terminal and the wiring (a portion straddling the imposition boundary and a portion to which the wire is connected in a later step) was exposed was formed.
Next, a silicone Ag paste (AGX manufactured by Toray Dow Corning Silicone Co., Ltd.) is applied by screen printing on the external terminals exposed in the opening (diameter 250 μm) of the insulating layer, and cured to a thickness. A 50 μm stress relaxation conductive layer was formed.
Next, a conductive layer having a thickness of 10 μm is formed on the stress relaxation conductive layer by electrolytic Cu plating, and an Ni layer (thickness of 3 μm) and an Au layer (thickness of 0.2 μm) are formed on the conductive layer by electrolytic plating. A barrier metal layer was formed.

On the other hand, for each imposition, Au bumps for connection were formed on the sensor terminals by the stud bump method using Au wires. In addition, a resin composition (World Rock, manufactured by Kyoritsu Chemical Industry Co., Ltd.) is applied by screen printing to an intermediate region between the active surface of the sensor and the region where the terminals are disposed, and semi-cured and sealed. Stop ribs (width 60 μm, height 20 μm) were formed.
Next, the multi-sided silicon wafer was diced to obtain a sensor chip of 5 mm × 5 mm.

Further, a glass substrate having a thickness of 500 μm was prepared as a protective material, and was divided into multiple faces (a square having a side of 7 mm). Next, a positive photoresist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the entire surface of the glass substrate, and exposed and developed through a photomask for lead wiring to form a resist pattern. Next, using the resist pattern as a mask, a Ti / Cu / Ni / Au laminated thin film (Au layer is the outermost surface) was formed by plasma CVD and plating, and then the resist pattern was peeled off. As a result, five lead wires were formed for each side of each imposition.
Next, for each imposition of the glass substrate, the sensor chip was fixed in alignment so that the sealing ribs were in contact with the glass substrate surface and the bumps were connected to the lead-out wiring.

Next, the wiring on the back surface of the sensor and the lead wiring on the glass substrate were connected by Au wire.
Next, a sealing material (CRP manufactured by Sumitomo Bakelite Co., Ltd.) was poured into each imposition boundary region and cured to form a sealing member so that the Au wire and the wiring on the back surface of the sensor were covered. However, the pouring amount of the sealing material was adjusted so as not to get over the insulating layer where the external terminal (barrier metal layer) was exposed.
Next, a solder ball having a diameter of 300 μm was mounted on the barrier metal layer by a ball mounting method to form an external terminal convex member.
Next, the multi-sided glass substrate was diced together with the sealing member to obtain the sensor package of the present invention. This sensor package had a size of 7 mm × 7 mm and a height of about 0.91 mm (including solder balls).

  The present invention can be applied in various fields where a small and highly reliable sensor is required.

It is a front view which shows one Embodiment of the sensor package of this invention. It is a rear view which shows one Embodiment of the sensor package of this invention. It is a schematic sectional drawing in the AA line of the sensor package shown by FIG. 1 and FIG. It is process drawing which shows one Embodiment of the manufacturing method of the sensor package of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the sensor package of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the sensor package of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sensor package 11 ... Sensor 11 '... Sensor chip 12 ... Active surface 13 ... Terminal 15 ... Wiring 16 ... External terminal 17 ... External terminal convex member 14, 20 ... Insulating layer 18a ... Stress relaxation conductive layer 18b ... Conductive layer 18c, 18d ... Barrier metal layer 19 ... Sealing rib 21 ... Protective material 22 ... Lead-out wiring 23 ... Bump 25 ... Wire 27 ... Sealing member 31 ... Silicon wafer 41 ... Protective material

Claims (6)

A sensor, and a protective material fixed to the sensor surface so as to face the active surface of the sensor surface via a gap,
The sensor has a plurality of terminals in the outer region of the active surface on the front surface, a plurality of wirings on the back surface, and external terminals are connected to the respective wirings, and external terminal convex members are connected to the external terminals. Is arranged,
The protective material has a plurality of lead wires in an outer region of the active surface of the sensor, and each lead wire is connected to a terminal of the sensor via a bump, and a wire on the back surface of the sensor via a wire. Connected to
A sensor package, wherein the wire and a connection portion between the wire and the wiring or the lead-out wiring are covered with a sealing member.   The sensor package according to claim 1, wherein the protective material is an infrared cut filter.   The sensor package according to claim 1, wherein a stress relaxation conductive layer is interposed between the external terminal and the external terminal convex member.   The sensor package according to claim 1, wherein the stress relaxation conductive layer is obtained by dispersing conductive particles in a synthetic rubber. Dividing the wafer into multiple impositions and producing a sensor for each imposition;
Forming an insulating layer covering the wafer on the surface opposite to the surface where the active surface of the sensor exists;
Forming a plurality of wirings and external terminals connected to the wirings on the insulating layer for each imposition;
Forming an insulating pattern so that a desired portion of the wiring and the external terminal are exposed for each imposition; and
Dicing the wafer with multiple faces to produce a sensor chip; and
A plurality of lead wirings are formed for each imposition of the protective material partitioned into multiple impositions, and the sensor chip is fixed for each imposition so that the active surface faces the protective material via the gap, Connecting the terminals of the sensor chip to the lead-out wiring via bumps;
Connecting the lead-out wiring and the wiring of the sensor chip with a wire for each imposition, and covering the wire, and the connection portion between the wire and the wiring, the lead-out wiring with a sealing member;
Dicing the multi-faceted protective material;
Forming the external terminal convex member on the external terminal either before or after the step of dicing the protective material.   6. The method of manufacturing a sensor package according to claim 5, wherein a stress relaxation conductive layer is formed on the external terminal, and the external terminal convex member is formed on the stress relaxation conductive layer.

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