JP2008102146A - Pressure detector and pressure detector assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and supersensitive pressure detector capable of accurately detecting external pressure over a long period. <P>SOLUTION: This pressure detector has: a substrate formed with a recessed part having a first face with an opening; a lid body installed on the first face side such that the lid body closes the opening, at least partially having electroconductivity; and a diaphragm pressure detection part having a fixed electrode provided on the inner face of the recessed part oppositely to the lid body. The first face is set as a facing face to an external mounting body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure detector and a pressure detector assembly used in a pressure detection device for detecting pressure.

  Conventionally, a capacitance type pressure detection device is known as a pressure detection device for detecting pressure. For example, as shown in a cross-sectional view in FIG. 3, this capacitance type pressure detection device is accommodated in a capacitance type pressure sensitive element 22 and a package 28 on a wiring substrate 21 made of a ceramic material or a resin material. And a semiconductor element 29 for operation. The pressure-sensitive element 22 is made of, for example, an electrically insulating material such as a ceramic material, and has an insulating base 24 having a concave portion in which one electrode 23 for forming a capacitance is attached at the center of the upper surface, and an upper surface of the insulating base 24. And an insulating plate 26 which is joined in a flexible state so as to form a sealed space with the insulating base 24 and the other electrode 25 for forming a capacitance is attached to the lower surface, and each capacitance. Each of the forming electrodes 23 and 25 is composed of an external lead terminal 27 for electrically connecting to the outside. The insulating plate 26 bends in response to an external pressure, thereby forming each capacitance. The capacitance formed between the electrodes 23 and 25 changes. Then, an external pressure can be detected by performing arithmetic processing on the change of the electrostatic capacitance with the semiconductor element 29 for arithmetic operation.

  However, according to this conventional pressure detection device, since the pressure-sensitive element 22 and the semiconductor element 29 are individually mounted on the wiring substrate 21, the pressure detection device is increased in size and the pressure detection electrode 23 is provided. The wiring between the 25 and the semiconductor element 29 becomes long, and an unnecessary capacitance is formed between the long wiring, so that the sensitivity is low.

  Accordingly, the applicant of the present application previously described in Japanese Patent Application No. 2000-178618, an insulating base having a mounting portion on which a semiconductor element is mounted on one main surface, and the surface of and inside the insulating base, A plurality of wiring conductors to which each electrode is electrically connected, and a first capacitor for forming a capacitance that is attached to the central portion of the other main surface of the insulating base and is electrically connected to one of the wiring conductors. An insulating plate joined in a flexible state so as to form a sealed space between the electrode and the other main surface of the insulating base, and a central portion of the main surface; and an inner main surface of the insulating plate There has been proposed a pressure sensing device package comprising a second electrode for forming a capacitance that is deposited opposite to one electrode and is electrically connected to the other one of the wiring conductors. According to this pressure detection device package, the first electrode for forming a capacitance is provided on the other main surface of the insulating base having the mounting portion on which the semiconductor element is mounted on one main surface. Since the insulating plate having the second electrode for forming the opposing capacitance on the inner surface is joined in a flexible state so as to form a sealed space between the other main surface of the insulating base, A pressure-sensitive element is integrally formed in a package that houses a semiconductor element. As a result, the pressure detection device can be reduced in size, and the wiring for connecting the pressure detection electrode and the semiconductor element can be shortened. Unnecessary capacitance generated between the wirings can be reduced.

  In the pressure detection device package proposed in Japanese Patent Application No. 2000-178618, the external connection conductor for mounting the package on the external electric circuit board is formed on the side opposite to the insulation plate. It was designed to be mounted on an external electric circuit board with the side facing up. And when the insulating plate side of the package is mounted face up in this way, if the foreign material comes in from the outside, the foreign material tends to collide with the insulating plate.

  Since the insulating plate is made of a brittle ceramic material, if the thickness is reduced to, for example, about 0.5 mm or less in order to increase the sensitivity of pressure detection, cracks and cracks may occur in the insulating plate due to such collision of foreign matter. When such cracks or cracks occur, the hermeticity of the sealed space between the insulating base and the insulating plate is lowered, and the external pressure cannot be detected accurately. Had.

  The present invention has been completed in view of the above-mentioned problems, and an object of the present invention is to provide a pressure detection device that is small in size and high in sensitivity and can accurately detect external pressure over a long period of time. There is to do.

  The pressure detector according to the present invention includes a base body provided with a recess having an opening on a first surface, and is attached to the first surface side so as to close the opening, and at least a part thereof is electrically conductive. And a diaphragm pressure detector configured to have a fixed electrode provided on the inner surface of the concave portion so as to face the lid, and the first surface is an external mounting body. It is characterized by being the opposite surface to.

  According to the pressure detector and the pressure detector assembly of the present invention, the external connection conductor that can be mounted with the insulating plate facing the external electric circuit board is formed on the insulating plate side of the outer peripheral portion of the insulating base. Therefore, it can be mounted on the external electric circuit board with the insulating plate side facing down. As a result, even if foreign matter comes to the package from the outside, the foreign matter does not collide with the insulating plate. It can prevent effectively that a crack and a crack generate | occur | produce.

  According to the pressure detector and the pressure detector assembly of the present invention, the first electrode for forming a capacitance is provided on the other main surface of the insulating base having the mounting portion on which the semiconductor element is mounted on one main surface. In addition, the insulating plate having the second electrode for forming the capacitance opposite to the first electrode on one main surface is flexible so as to form a sealed space between the other main surface of the insulating base. Since the pressure sensitive element is integrated with the package that accommodates the semiconductor element, the pressure detecting device can be downsized. In addition, since the first electrode and the second electrode for forming the capacitance are connected to the semiconductor element via the wiring conductor provided on the insulating base, the first electrode and the second electrode are connected to the semiconductor element at a short distance. As a result, an unnecessary capacitance generated between these wiring conductors can be made small, and a highly sensitive pressure detecting device can be provided. In addition, since the external connection conductor is formed on the insulating substrate side of the outer periphery of the insulating base so that the insulating plate can be mounted facing the external electric circuit board, the insulating plate side faces the external electric circuit board. As a result, the insulating plate is well protected from the collision of foreign matter by the external electric circuit board, and the insulating plate is not cracked. Therefore, it is possible to provide a pressure detection device that can always detect the external pressure over a long period of time while maintaining the hermeticity of the sealed space.

  Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a pressure detector assembly configured to include the pressure detector of the present invention, in which 1 is an insulating substrate, 2 is an insulating plate, and 3 is a semiconductor. It is an element.

  The insulating substrate 1 is a laminated body made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or glass-ceramics. For example, in the case of an aluminum oxide sintered body, an appropriate organic binder, solvent, plasticizer, and dispersant are added to and mixed with ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. Then, it is made into a mud shape and formed into a sheet shape by adopting a conventionally known doctor blade method, and then a plurality of ceramic green sheets are obtained.・ By cutting, a green ceramic molded body for the insulating substrate 1 is obtained. It is manufactured by firing at a temperature of 1600 ° C..

The insulating base 1 is formed with a recess 1a for accommodating the semiconductor element 3 at the center of the lower surface thereof, thereby functioning as a container for accommodating the semiconductor element 3. The central portion of the bottom surface of the recess 1a is a mounting portion 1b on which the semiconductor element 3 is mounted. The semiconductor element 3 is mounted on the mounting portion 1b and the resin sealing such as an epoxy resin is provided in the recess 1a. The semiconductor element 3 is sealed by filling the material 4. In this example, the semiconductor element 3 is sealed by filling the recess 1a with the resin sealing material 4. However, the semiconductor element 3 has a lid made of metal or ceramics on the lower surface of the insulating base 1 to form the recess 1a. It may be sealed by bonding so as to block.

  A plurality of wiring conductors 5 connected to the respective electrodes of the semiconductor element 3 are led out to the mounting portion 1b. The wiring conductors 5 and the respective electrodes of the semiconductor element 3 are made of a conductive material such as a solder bump 6. By connecting through the electrical connection means, each electrode of the semiconductor element 3 and each wiring conductor 5 are electrically connected, and the semiconductor element 3 is fixed to the mounting portion 1b. In this example, the electrode of the semiconductor element 3 and the wiring conductor 5 are connected via the solder bumps 6. However, the electrode of the semiconductor element 3 and the wiring conductor 5 are connected to other types of electrical connections such as bonding wires. It may be connected by means.

  The wiring conductor 5 functions as a conductive path for electrically connecting each electrode of the semiconductor element 3 to an external electric circuit and a first electrode 7 and a second electrode 9 described later, and a part of the wiring conductor 5 is an outer periphery of the insulating base 1. Another part is electrically connected to the first electrode 7 and the second electrode 9 which are led out to the external connection conductor 11 and described later. Then, each electrode of the semiconductor element 3 is electrically connected to these wiring conductors 5 via solder bumps 6 and the semiconductor element 3 is sealed with a resin sealing material 4, and then the external connection conductor 11 is connected to the outside. By bonding to the wiring conductor 13 of the electric circuit board 12 via a conductive bonding material such as solder 14, the semiconductor element 3 accommodated therein is electrically connected to the external electric circuit.

  Such a wiring conductor 5 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, dispersant, etc. to metal powder such as tungsten. The paste is applied in a predetermined pattern to a ceramic green sheet for the insulating substrate 1 by using a conventionally known screen printing method, and this is fired together with a green ceramic molded body for the insulating substrate 1 to synthesize the inside of the insulating substrate 1. In addition, a predetermined pattern is formed on the surface.

  In order to prevent the wiring conductor 5 from being oxidized and corroded on the exposed surface of the wiring conductor 5 and to improve the bonding between the wiring conductor 5 and a conductive bonding material such as solder, A nickel plating layer having a thickness of about 1 to 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially deposited.

  In addition, a recessed portion 1c for forming a sealed space having a depth of about 0.01 to 5 mm is formed in the central portion of the upper surface of the insulating substrate 1. As will be described later, the recess 1c is for forming a sealed space S between the recess 1c, and a first electrode 7 for forming a capacitance is attached to the bottom surface of the recess 1c. ing.

  The first electrode 7 is for forming a capacitance for a pressure sensitive element together with a second electrode 9 described later, and is formed in a substantially circular pattern, for example. The first electrode 7 is connected to one of the wiring conductors 5a. When the electrodes of the semiconductor element 3 are connected to the wiring conductor 5a through electrical connection means such as solder bumps 6, the semiconductor The electrode of the element 3 and the first electrode 7 are electrically connected.

The first electrode 7 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, or dispersant to metal powder such as tungsten. The paste is printed and applied to a ceramic green sheet for the insulating substrate 1 by using a conventionally known screen printing method, and this is fired together with a green ceramic molded body for the insulating substrate 1 so as to be predetermined on the bottom surface of the recess 1c of the insulating substrate 1. The pattern is formed. In order to prevent the first electrode 7 from being oxidatively corroded, a nickel plating layer having a thickness of about 1 to 10 μm is usually applied to the exposed surface of the first electrode 7.

  In addition, a frame-shaped first bonding metallization layer 8 is attached to the periphery of the recess 1c on the upper surface of the insulating substrate 1, and the second electrode 9 is formed on the lower surface of the first bonding metallization layer 8. The insulating plate 2 having the second bonding metallization layer 10 is bonded via a conductive bonding material such as a silver-copper brazing material.

  One of the wiring conductors 5b is connected to the first bonding metallization layer 8 so that the electrode of the semiconductor element 3 is electrically connected to the wiring conductor 5b through an electrical connection means such as a solder bump 6. The second electrode 9 and the electrode of the semiconductor element 3 are electrically connected through the wiring conductor 5b, the first bonding metallization layer 8, and the second bonding metallization layer 10.

The first bonding metallization layer 8 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, or dispersant to metal powder such as tungsten. The paste is printed and applied to a ceramic green sheet for the insulating substrate 1 using a conventionally known screen printing method, and is fired together with a green ceramic molded body for the insulating substrate 1 to surround the recess 1c on the upper surface of the insulating substrate 1. It is formed in a frame-shaped predetermined pattern. The exposed surface of the first bonding metallization layer 8 prevents the first bonding metallization layer 8 from being oxidatively corroded and provides strong bonding between the first bonding metallization layer 8 and the conductive bonding material. Therefore, a nickel plating layer having a thickness of about 1 to 10 μm is usually applied.

  An insulating plate 2 is joined to the upper surface of the insulating base 1 so as to form a sealed space S between the concave portion 1c. The insulating plate 2 is a substantially flat plate having a thickness of 0.01 to 5 mm made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass-ceramic. It functions as a so-called pressure detection diaphragm that bends in response to pressure.

  In addition, since the mechanical strength of the insulating plate 2 is less than 0.01 mm, the mechanical strength of the insulating plate 2 is small. Therefore, there is a high risk of destruction when a large external pressure is applied thereto. On the other hand, when it exceeds 5 mm, it becomes difficult to bend at a small pressure, and it becomes unsuitable as a diaphragm for pressure detection. Therefore, the thickness of the insulating plate 2 is preferably in the range of 0.01 to 5 mm.

  If such an insulating plate 2 is made of, for example, an aluminum oxide sintered body, a suitable organic binder, solvent, plasticizer, dispersion for ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc. A ceramic green sheet is obtained by adding an agent and mixing it into a mud and forming it into a sheet using the well-known doctor blade method, and then punching or cutting the ceramic green sheet appropriately. The raw ceramic molded body for the insulating plate 2 is obtained by processing, and the green ceramic molded body is manufactured by firing at a temperature of about 1600 ° C.

  A substantially circular second electrode 9 for forming a capacitance is attached to the center of the lower surface of the insulating plate 2. The second electrode 9 functions as an electrode for forming a capacitance for the pressure sensitive element together with the first electrode 7 described above.

  The second electrode 9 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, or dispersant to metal powder such as tungsten. The paste is printed and applied to a ceramic green sheet for the insulating plate 2 using a conventionally known screen printing method, and this is fired together with a green ceramic molded body for the insulating plate 2 so as to be placed at the center of the lower surface of the insulating plate 2. A predetermined pattern is formed. In order to prevent the second electrode 9 from being oxidatively corroded, a nickel plating layer having a thickness of about 1 to 10 μm is usually applied to the exposed surface of the second electrode 9.

  Further, a frame-like second bonding metallization layer 10 electrically connected to the second electrode 9 is deposited on the outer peripheral portion of the lower surface of the insulating plate 2. The second bonding metallization layer 10 functions as a bonding base metal layer for bonding the insulating plate 2 to the insulating substrate 1, and the first bonding metallization layer 8 and the second bonding metallization layer 10 are made of silver-copper. The insulating plate 2 is bonded to the insulating base 1 by bonding via a conductive bonding material such as wax, and the wiring conductor 5b and the second electrode 9 are electrically connected.

  Such a second bonding metallization layer 10 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and an appropriate organic binder, solvent, plasticizer, or dispersing agent is added to and mixed with metal powder such as tungsten. The obtained metallized paste is printed and applied to a ceramic green sheet for the insulating plate 2 using a conventionally well-known screen printing method, and this is fired together with a green ceramic molded body for the insulating plate 2 to form the bottom surface of the insulating plate 2. A predetermined pattern is formed on the outer periphery. The second bonding metallization layer 10 is prevented from being oxidized and corroded on the surface of the second bonding metallization layer 10 and the bonding between the second bonding metallization layer 10 and the conductive bonding material is improved. Further, usually, a nickel plating layer having a thickness of about 1 to 10 μm is applied.

  At this time, the first electrode 7 and the second electrode 9 are opposed to each other with a sealed space S formed between the insulating base 1 and the insulating plate 2 interposed therebetween. A predetermined capacitance is formed according to the area of the second electrode 9 and the distance between the first electrode 7 and the second electrode 9. When an external pressure is applied to the upper surface of the insulating plate 2, the insulating plate 2 bends toward the insulating base 1 in accordance with the pressure, and the interval between the first electrode 7 and the second electrode 9 changes. Since the capacitance between the first electrode 7 and the second electrode 9 changes, it functions as a pressure-sensitive element that senses a change in external pressure as a change in capacitance. Then, the change in the electrostatic capacity is transmitted to the semiconductor element 3 accommodated in the recess 1a through the wiring conductors 5a and 5b, and this is processed by the semiconductor element 3 to know the magnitude of the external pressure. Can do.

  In addition, when the space | interval of the 1st electrode 7 and the 2nd electrode 9 is less than 0.01 mm in 1 atmosphere, when a big pressure is applied to the insulating board 2, the 1st electrode 7 and the 2nd electrode 9 are There is a risk that the pressure cannot be detected by contact, and if it exceeds 5 mm, the capacitance formed between the first electrode 7 and the second electrode 9 becomes small, and the pressure is reduced. There is a tendency that the sensitivity to detect is low. Therefore, the distance between the first electrode 7 and the second electrode 9 is preferably in the range of 0.01 to 5 mm at 1 atmosphere.

  Further, a protrusion 1d surrounding the insulating plate 2 is formed on the outer peripheral portion of the insulating base 1, and a substantially semicircular cutout 1e is formed from the upper surface of the protrusion 1d to the side of the insulating base 1 in a top view. An external connection conductor 11 for electrically connecting the semiconductor element 3 to an external electric circuit is electrically connected to the wiring conductor 5 on the surface of the notch 1e and the upper surface of the protrusion 1d. It is attached in a connected state.

  Then, each electrode of the semiconductor element 3 is electrically connected to the wiring conductor 5 via an electrical connection means such as a solder bump 6 and the semiconductor element 3 is sealed with a resin sealing material 4 and then externally connected. By connecting the conductor 11 to the wiring conductor 13 of the external electric circuit board 12 via a conductive bonding member such as solder 14, the package is mounted on the external electric circuit board 12 and the electrode of the semiconductor element 3 accommodated therein is provided. It will be electrically connected to an external electrical circuit.

  At this time, according to the pressure detector of the present invention, the external connection conductor 11 is formed on the insulating plate 2 side and is mounted on the external electric circuit board 12 with the insulating plate 2 side on the back side. The plate 2 is protected by being covered with the external electric circuit board 12, and even if foreign matter comes from the outside to the package, the foreign matter does not collide with the insulating plate 2, so that the insulating plate 2 is not cracked or cracked. It does not occur. Therefore, there is provided a pressure detection device capable of accurately detecting the external pressure over a long period of time without reducing the airtightness of the sealed space S formed between the insulating base 1 and the insulating plate 2. be able to.

  The external connection conductor 11 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and an appropriate organic binder, solvent, plasticizer, dispersant, or the like is added to and mixed with the metal powder such as tungsten. The metallized paste obtained in this way is printed and applied in a predetermined pattern on a ceramic green sheet for the insulating substrate 1 using a conventionally known screen printing method, and this is fired together with the green ceramic molded body for the insulating substrate 1 for insulation. A predetermined pattern is formed on the upper surface of the protrusion 1d and the surface of the notch 1e of the base 1. Further, the external connection conductor 11 is prevented from being oxidatively corroded on the exposed surface of the external connection conductor 11 and the bonding between the external connection conductor 11 and a conductive bonding material such as solder 14 is improved. Therefore, normally, a nickel plating layer having a thickness of about 1 to 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially deposited.

  As described above, according to the pressure detector and the pressure detector assembly of the present invention, the other main surface of the insulating base 1 having the mounting portion 1b on which the semiconductor element 3 is mounted on one main surface is statically mounted. A first electrode 7 for forming a capacitance is provided, and an insulating plate 2 having a second electrode 9 for forming a capacitance opposite to the first electrode 7 on the inner main surface is sealed between the insulating base 1 and the space. Since it is joined in a flexible state so as to form S, the container for housing the semiconductor element 3 and the pressure sensitive element are integrated, and as a result, the pressure detection device can be miniaturized. In addition, since the first electrode 7 and the second electrode 9 for forming the capacitance are connected to the semiconductor element 3 via the wiring conductors 5a and 5b provided on the insulating base 1, the first electrode 7 and the second electrode 9 can be connected to the semiconductor element 3 at a short distance, and as a result, it is possible to provide a highly sensitive pressure detecting device by reducing unnecessary capacitance generated between the wiring conductors 5a and 5b. . In addition, since the external connection conductor 11 is formed on the insulating plate 2 side of the outer periphery of the insulating base 1 so that the insulating plate 2 can be mounted so as to face the external electric circuit substrate 12. It can be mounted with the insulating plate 2 side facing down. As a result, when this package is mounted on the external electric circuit board 12, the external electric circuit board 12 protects the insulating plate 2 from collision of foreign matter from the outside. As a result, no cracks or the like occur in the insulating plate 2. Therefore, the airtightness of the sealed space S is always maintained, and the external pressure can be accurately detected over a long period.

  Thus, according to the above-described package for the pressure detection device, the semiconductor element 3 is mounted on the mounting portion 1b, and each electrode of the semiconductor element 3 and the metallized wiring conductor 5 are electrically connected. By sealing, the pressure detection device is small and highly sensitive, and can detect the external pressure accurately over a long period of time.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the example of the embodiment described above, the insulating base 1 and the insulating plate 2 are joined by the brazing material. However, as shown in the cross-sectional view of FIG. 2, the insulating base 1 and the insulating plate 2 are simultaneously fired. May be joined together by sintering. In that case, it is not necessary to provide the first bonding metallization layer 8 and the second bonding metallization layer 10.

  In the embodiment shown in FIG. 2, the same reference numerals as those used in FIG. 1 are used for portions that are substantially the same as those of the embodiment shown in FIG.

It is sectional drawing which shows an example of the pressure detector and pressure detector assembly of this invention. It is sectional drawing which shows the other example of embodiment of the pressure detector of this invention. It is sectional drawing which shows the conventional pressure detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulating base | substrate 1b ... Mounting part 2 ... Insulating board 3 ... Semiconductor element 5 ... Wiring conductor 7 ... First electrode 9 ... .... Second electrode
11: External connection conductor S: Sealed space

Claims (7)

A base provided with a recess having an opening on the first surface;
The lid is attached to the base so as to close the opening, and at least a part of the lid is conductive, and includes a fixed electrode provided on the inner surface of the recess facing the lid. A diaphragm pressure detector,
The pressure detector, wherein the first surface is a surface facing an external mounting body.   2. The pressure detector according to claim 1, wherein the lid is disposed at a position closer to a bottom side of the concave portion than the first surface.   The pressure detector according to claim 1, wherein an external connection conductor is disposed on the first surface.   The pressure detector according to claim 3, wherein a semiconductor element electrically connected to each of the lid, the fixed electrode, and the external connection conductor is disposed on the base.   The pressure detector according to claim 4, wherein the semiconductor element is arranged on a side of the base opposite to the first surface. A pressure detector according to any one of claims 1 to 5;
A pressure detector assembly comprising: a mounting body that is disposed to face the first surface of the pressure detector and on which the pressure detector is mounted. The mounting body is an electric circuit board provided with a wiring conductor on the surface,
The pressure detector having an external connection conductor disposed on the first surface is mounted on the electric circuit board in a state where the external connection conductor and the wiring conductor are connected. The pressure detector assembly according to claim 6.

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