This application is the National Phase of PCT/JP2011/000909, filed Feb. 18, 2011, which claims priority to Japanese Application No. 2010-051083, filed Mar. 8, 2010, the disclosures of which are hereby incorporated by reference in their entirety.
The present invention relates to an electronic device, a wiring board, and a method of shielding a noise.
In an electronic device, there are cases where a noise generated from an electronic component propagates through a parallel flat plane that is formed by a power source-ground plane as a kind of a waveguide so as to have an adverse influence on the other electronic components, a wireless circuit located close thereto, or the like. Therefore, countermeasures for the noise are generally taken, and many techniques have been developed.
Recently, it has been disclosed that the propagation characteristics of electromagnetic waves can be controlled by periodically arranging a conductive body pattern having a specific structure. Particularly, a meta material configured so as to suppress the propagation of electromagnetic waves in a specific frequency band is called an electronic band gap structure (hereinafter, referred to as an EBG structure), and a countermeasure for noise using the EBG structure has attracted attention.
As a technique of such a type, for example, there is a technique described in Patent Document 1 (U.S. Pat. No. 6,262,495 Specification). In FIG. 2 of Patent Document 1, a structure, that is, a so-called EBG structure of a mushroom type is illustrated, in which a plurality of island-shaped conduction elements is arranged on the upper side of a sheet-shaped conduction plane, and each of the island-shaped conduction elements is connected to the conduction plane through a via.
In addition, as a technique of such a type, there is a technique disclosed in Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-253929). In FIG. 4 of Patent Document 2, an EBG structure that is configured by connecting two conductive bodies facing each other is illustrated. In addition, the inductance component of a conductive body that is formed in a lower level out of the two conductive bodies facing each other is increased by applying a conductive body pattern for which a large reflection coefficient is acquired in a Bragg frequency.
In the case of an electronic device having multiple layers, noise propagates from an electronic component to a wiring or a parallel flat plates having an electric potential difference therebetween. In addition, in a case where there is a hole or a gap in the parallel flat plates, the leakage of noise from the gap needs to be considered. In addition, in a case where an electronic component is mounted on one face of the multi-layer board, noise propagating from the electronic component to the air or noise propagating on one face, that is, a so-called surface wave needs to be considered. Thus, in the case of the above-described electronic device, by simply configuring only the EBG structure, an adequate countermeasure cannot be achieved.
The present invention is devised in view of the above-described circumstances, and the object thereof is to provide an electronic device, a wiring board, and a method of shielding a noise that are capable of sufficiently preventing the leakage of a noise propagating from a mounted electronic component.
According to the present invention, there is provided an electronic device including: a wiring board that includes a plurality of layers; an electronic component that is mounted on one face of the wiring board; and a metal cap that covers the electronic component, wherein the wiring board includes: a first conductive body that is located on the one face, is arranged so as to surround the electronic component, and is connected to an end portion of the metal cap; a second conductive body that is located in a first layer, is connected to the electronic component through a first connection member, and has a gap; a third conductive body that is located in a second layer facing the one face through the first layer and is connected to the electronic component through a second connection member; and a plurality of fourth conductive bodies that are repeatedly arranged so as to surround the first connection member, the second connection member and the gap, wherein the second conductive body and the third conductive body extend so as to include at least a part of an area that is surrounded by the plurality of fourth conductive bodies and at least a part of an area facing the plurality of fourth conductive bodies in the plan view.
In addition, according to the present invention, there is provided a wiring board including: a first conductive body that is located on one face, is arranged so as to surround a mounting area of an electronic component, and is connected to an end portion of a metal cap; a second conductive body that is located in a first layer, is connected to the electronic component through a first connection member, and has a gap; a third conductive body that is located in a second layer facing the one face through the first layer and is connected to the electronic component through a second connection member; and a plurality of fourth conductive bodies that are repeatedly arranged so as to surround the first connection member and the second connection member, wherein the second conductive body and the third conductive body extend so as to include at least a part of an area that is surrounded by the plurality of fourth conductive bodies and at least a part of an area facing the plurality of fourth conductive bodies in the plan view.
Furthermore, according to the present invention, there is provided a method of shielding a noise that is used for shielding the noise that is generated by an electronic component mounted on one face of a wiring board including: shielding a noise propagating from the electronic component to the air using a metal cap that covers the electronic component; shielding a noise propagating above the surface of one face using a first conductive body that is located on the one face, is arranged so as to surround the electronic component, and is connected to an end portion of the metal cap; shielding a noise propagating between a second conductive body that is located in a first layer, is connected to the electronic component through a first connection member, and has a gap and a third conductive body that is located in a second layer facing the one face through the first layer and is connected to the electronic component through a second connection member, in an area in which a plurality of fourth conductive bodies that are repeatedly arranged so as to surround the first connection member and the second connection member face at least one of the second conductivity body or the third conductivity body; and shielding a noise that propagates between the second conductive body and the third conductive body and further leaks from the gap using an area in which the plurality of fourth conductive bodies face at least one of the first conductive body and the second conductive body or the metal cap.
According to the present invention, an electronic device, a wiring board, and a method of shielding a noise that are capable of preventing the leakage of a noise propagating from a mounted electronic component are provided.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numeral is assigned to the same constituent elements, and the description thereof will not be presented as is appropriate.
In addition, in
In a case where the electronic component 101 is mounted, a connection member 116 (first connection member) connects the electronic component 101 and a power source plane 131 that is located on the C layer 130. Here, although only one connection member 116 that is connected to the electronic component 101 is illustrated in the diagram, a plurality of connection members may be arranged.
In a case where the electronic component 101 is mounted, a connection member 115 (second connection member) connects the electronic component 101 and a ground plane 151 that is located on the E layer 150. Here, although only one connection member 115 that is connected to the electronic component 101 is illustrated in the diagram, a plurality of connection members may be arranged.
The metal cap pad 113 (first conductive body) is located on the A layer 110 (one face) and surrounds the connection member 115 and the connection member 116. In addition, the metal cap 102 is mounted on the wiring board 100 by being connected to the metal cap pad 113 using solder or the like.
In addition, in
Here, the conductive body elements 121 are island-shaped conductive bodies that are arranged so as to be separate from each other. In addition, the conductive body elements 141 are island-shaped conductive bodies that are arranged so as to be separate from each other. An area of the B layer 120 in which the conductive body elements 121 are not arranged and an area of the D layer 140 in which the conductive body elements 141 are not arranged are formed as insulating bodies and are insulated by using the connection member 115 or the like.
Here, surrounding the connection members 115 and 116 and the gap 137 by the conductive body elements 121 (or the conductive body elements 141) means surrounding the position of the connect ion members 115, the position of the connection member 116, and the position of the gap 137 are surrounded in the plan view. In addition, being repeatedly arranged means that at least three or more conductive body elements 121 and 141 are consecutively arranged separate from each other. Since the conductive body elements 121 and 141 are separate from each other, the entirety of the connection member 115 in the plane direction is not surrounded in a strict sense. A gap between the conductive body elements 121 and a gap between the conductive body elements 141 may be determined such that a noise of a frequency band that is a suppression target can be sufficiently suppressed.
Each conductive body element 121 is connected to the metal cap pad 113 through the connection member 122, and each conductive body element 141 is connected to the ground plane 151 through the connection member 142. In addition, the conductive body element 121 does not need to be necessarily connected to the metal cap pad 113. The conductive body element 141 does not need to be necessarily connected to the ground plane 151.
The ground plane 151 is provided with a reference electric potential through grounding or the like and serves as the ground that gives the reference electric potential to the electronic component 101. In addition, the ground plane 151 may be regarded to be provided with the reference electric potential due to its impedance that is lower than that of the other conductive bodies inside the wiring board 100.
By configuring as described above, the conductive body element 121 configures a unit cell of the EBG structure of a so-called mushroom type together with the metal cap pad 113, the power source plane 131, and the connection member 122. In addition, the conductive body element 141 configures a unit cell of the EBG structure of the mushroom type together with the ground plane 151, the power source plane 131, and the connection member 142. Described in more detail, the connection members 122 and 142 correspond to the shaft portion of the mushroom and forms inductance. On the other hand, the conductive body elements 121 and 141 correspond to a head portion of the head portion and form capacitance between the conductive body elements 121 and 141 and the opposing power source plane 131.
The EBG structure of the mushroom type can be represented by an equivalent circuit in which parallel flat plates are shunt with a serial resonance circuit that is configured by the above-described capacitance and the above-described inductance, and the resonant frequency of the above-described serial resonant circuit provides the center frequency of the band gap. Accordingly, by increasing the capacitance by approaching the conductive body elements 121 and 141 to opposing planes each forming the capacitance, the frequency of the band gap zone can be configured to be low. However, even in a case where the conductive body elements 121 and 141 are not configured to approach the opposing planes, there is no influence on the essential effect of the present invention.
By periodically arranging the such unit cells, a noise that propagates to the A layer 110 to the E layer 150 can be suppressed. In addition, it is preferable that the above-described EBG structure has a band gap zone that includes the frequency of a noise that is generated by the electronic component 101.
Here, the unit cell is a minimum unit that configures the EBG structure, and the wiring board 100 can have the characteristics of the EBG structure by including unit cells that are repeatedly arranged.
In addition, a gap between the conductive body element 121 and the metal cap pad 113, a gap between the conductive body element 141 and the ground plane 151, the thicknesses of the connection members 122 and 142, a mutual cap between the conductive body elements 121, a mutual gap between the conductive body elements 141, and the like, the frequency band that is a suppression target can be set to a desired value.
Furthermore, it is preferable that the mutual gap between unit cells that are repeatedly arranged, particularly, the conductive body elements 121 and 141 or the connection members 122 and 142 is periodical. The reason for this is that, in a case where unit cells are periodically arranged, the electromagnetic waves propagating through the EBG structure incurs Bragg reflection due to the periodicity, and accordingly, a noise propagation suppressing effect for a broad band can be acquired. However, the mutual gap between the conductive body elements 121 and the mutual gap between the conductive body elements 141 may not necessarily coincide with each other. Similarly, the mutual gap between the connection members 122 and the mutual gap between the connection members 142 may not necessarily coincide with each other. In addition, it is apparent that the unit cells do not need to be periodically arranged, and the effects of the present invention can be acquired as long as the unit cells are repeatedly arranged so as to surround a first area.
The unit cell described in this embodiment is an example, and various forms may be employed in a range in which the EBG structure can be configured. For example,
The EBG structure of the open stub type can be represented by an equivalent circuit in which parallel flat plates are shunt with a serial resonance circuit that is configured by the above-described open stub and the above-descried inductance, and the resonant frequency of the above-described serial resonant circuit provides the center frequency of the band gap. Accordingly, by increasing the stub length of the open stub formed so as to include the above-described conductive body elements 121 and 141, the frequency of the band gap zone can be configured to be low.
In addition, it is preferable that the conductive body elements 121 and 141 that form the microstrip lines and the opposing planes are close to each other. The reason for this is that, as a distance between the conductive body element and the opposing plane becomes shorter, the characteristic impedance of the above-described micro strip line is lowered, and the band gap zone can be configured to be a broad band. However, even in a case where the conductive body elements 121 and 141 are not configured to be close to the opposing planes, the essential effects of the present invention are not influenced at all.
The conductive body elements 121 and 141 illustrated in
The EBG structure of the mushroom type can be represented by an equivalent circuit in which parallel flat plates are shunt with a serial resonance circuit that is configured by the above-described capacitance and the above-described inductance, and the resonant frequency of the above-described serial resonant circuit provides the center frequency of the band gap. Accordingly, by increasing the capacitance by configuring the conductive body elements 121 and 141 to approach opposing planes that form capacitance or by increasing the inductance by increasing the length of the inductor, the frequency of the band gap zone can be configured to be low. However, even in a case where the conductive body elements 121 and 141 are not configured to approach the opposing planes, there is no influence on the essential effect of the present invention.
Here, the advantages of the first embodiment will be described. Ina case where the electronic component 101 and the metal cap 102 are mounted on the wiring board 100 according to this embodiment, a noise that propagates from the electronic component 101 through the air can be shielded by the metal cap 102. In addition, a noise that propagates on the A layer 110, that is, a so-called a surface wave can be shielded by the metal cap pad 113 that surrounds the electronic component 101. Furthermore, a noise that propagates between the power source plane 131 and the ground plane 151 can be shielded by the EBG structure that is formed by an area in which a plurality of the conductive body elements 141 and at least one of the power source plane 131 and the ground plane 151 face each other. In addition, a noise that propagates between the power source plane 131 and the ground plane 151 and further leaks from the gap 137 can be shielded through the EBG structure that is configured by an area in which a plurality of the conductive body elements 121 and at least one of the metal cap pad 113 and the power source plane 131 face each other or the metal cap 102. In other words, since a countermeasure is taken in the wiring board 100 for all the directions of the noise propagating from the electronic component 101, the leakage of the noise can be prevented.
In addition, by including the frequency of a noise that is generated from the electronic component 101 in the band gap zone of the EBG structure that is configured by this embodiment, a higher noise suppressing effect can be acquired.
Furthermore, in this embodiment, since the metal cap pad 113 is also used as one of the constituent elements of the EBG structure, mounting can be performed by saving the space. Accordingly, the wiring board 100 can be miniaturized.
In addition, in
The metal cap pad 213 (first conductive body) is located on the A layer 210 and surrounds the connection members 215, 216, 217, and 218. In addition, an end portion of the metal cap 202 is connected to the metal cap pad 213 using solder or the like. Furthermore, the shape of the metal cap 202 may be various forms. For example, the shape of the metal cap 202 may be a polyhedron or a sphere. In addition, the shape of the metal cap 202 may be a mesh having an opening to some degree from which a noise does not leak.
A connection member 212 is a through via that passes through in a direction perpendicular to the plane direction and connects the metal cap pad 213, the ground plane 271, and conductive body elements 231 and 251 (fourth conductive body).
In addition, in
In the electronic device 200 according to this embodiment, the electronic component 201 is located in an area overlapping a part of a gap 244. The reason for this is that, in a case where power is assumed to be supplied to the single electronic component 201 from the power source plane 241 (or 242 or 243), the connection to the power source plane 241 (or 242 or 243) can be made in a relatively easy manner. However, the electronic component 201 does not necessarily need to be disposed in an area overlapping the gap 244 in the plan view.
In addition, in this embodiment, a plurality of the conductive body elements 231 and 251 is arranged in any direction viewed from the electronic component 201. By arranging as such, a noise can be shielded more effectively than in a case where the conductive body elements are arranged in a single column as in the first embodiment.
The power source plane 241 is connected to the connection member 215, the power source plane 242 is connected to the connection member 219, and the power source plane 243 is connected to the connection member 214. In addition, since the connection member 212 or the connection member 216 are connected to the ground plane 271, an opening is disposed in the power source plane 241 (or 242 or 243) that allows the connection member 212 or the connection member 216 to passes through it, and the power source plane 241 (or 242 or 243), the connection member 212 or the connection member 216 are insulated from each other. In addition, a part or the whole of the conductive body elements 231 and 251 are arranged so as to face the opening through which the connection member 212 passes. Furthermore, the conductive body elements 231 and 251 that face the opening are larger than the opposing opening. In other words, apart of the conductive body element 231 faces a conductive body (apart of the power source planes 241, 242, and 243) disposed on the periphery of the opening, and apart of the conductive body element 251 faces the conductive body (parts of the power source planes 241, 242, and 243) disposed on the periphery of the opening.
In this embodiment, although connect ion points with the connection members 214, 215, and 219 are arranged in all the power source planes 241, 242, and 243 illustrated in the diagram, the connection points do not need to be arranged in all the power source planes. In other words, connection points with the connection members 214, 215, and 219 may be disposed in at least one of the power source planes 241, 242, and 243.
The ground plane 271 is provided with a reference electric potential through grounding or the like and serves as the ground that gives the reference electric potential to the electronic device 200. In addition, the ground plane 271 may be regarded to be provided with the reference electric potential due to its impedance that is lower than that of the other conductive bodies inside the electronic device 200.
By configuring as described above, the conductive body elements 231 and 251 configures at least a part of a unit cell of the EBG structure together with the opposing metal cap pad 213 and the ground plane 271 or the connection member 212. In addition, it is preferable that the above-described EBG structure includes the frequency of a noise that is generated by the electronic component 201 in the band gap zone.
The unit cell described in this embodiment is an example, and various forms may be employed in a range in which the EBG structure can be configured.
The above-described structure illustrated in
The structure illustrated here, similarly to the EBG structure of the mushroom type, can be represented by an equivalent circuit in which parallel flat plates that are formed by the metal cap pad 213 and the power source plane 241 (or 242 or 243) or parallel flat plates formed by the power source plane 241 (or 242 or 243) and the ground plane 271 are shunt with a serial resonance circuit that is configured by the above-described capacitance and the above-described inductance, and the resonant frequency of the above-described serial resonant circuit provides the center frequency of the band gap. Accordingly, by increasing the capacitance by approaching the conductive body elements 231 and 251 to opposing planes each forming the capacitance, the frequency of the band gap zone can be configured to be low. However, even in a case where the conductive body elements 231 and 251 are not configured to approach the opposing planes, there is no influence on the essential effect of the present invention.
By employing this structure, the EBG structure can be formed in the parallel flat plates using the through via. Generally, while a non-through via is laminated after the via is processed for each layer, a through via is formed by forming a through hole using a drill after all the layers are laminated and plating the inner face of the through hole, and accordingly, the manufacturing cost can be lowered than that of a case where a non-through via is used.
The structure illustrated in
The structure illustrated in
In addition, it is preferable that the conductive body elements 231 and 251 that form the microstrip lines and the opposing planes are close to each other. The reason for this is that, as a distance between the conductive body element and the opposing plane becomes shorter, the characteristic impedance of the above-described micro strip line is lowered, and the band gap zone can be configured to be a broad band. However, even in a case where the conductive body elements 231 and 251 are not configured to be close to the opposing planes, the essential effects of the present invention are not influenced at all.
By employing the structure illustrated here, the EBG structure can be formed in the parallel flat plates using the through via. Generally, while a non-through via is laminated after the via is processed for each layer, a through via is formed by forming a through hole using a drill after all the layers are laminated and plating the inner face of the through hole, and accordingly, the manufacturing cost can be lowered than that of a case where a non-through via is used.
The above-described structure illustrated in
The structure illustrated in
By employing the structure illustrated here, the EBG structure can be formed in the parallel flat plates using the through via. Generally, while a non-through via is laminated after the via is processed for each layer, a through via is formed by forming a through hole using a drill after all the layers are laminated and plating the inner face of the through hole, and accordingly, the manufacturing cost can be lowered than that of a case where a non-through via is used.
The above-described structure illustrated in
The EBG structure of the inductance increasing type can be represented by an equivalent circuit in which parallel flat plates, which are formed by the metal cap pad 213 and the power source plane 241 (or 242 or 243), or parallel flat plates, which are formed by the power source plane 241 (or 242 or 243) and the ground plane 271, are shunt with a serial resonance circuit that is configured by the above-described capacitance and the above-described inductance, and the resonant frequency of the above-described serial resonant circuit provides the center frequency of the band gap. Accordingly, by increasing the capacitance by approaching the conductive body elements 231 and 251 to opposing planes each forming the capacitance or increasing the inductance by increasing the length of the inductor, the frequency of the band gap zone can be configured to be low. However, even in a case where the conductive body elements 231 and 251 are not configured to approach the opposing planes, there is no influence on the essential effect of the present invention.
In the configuration illustrated in
Also in the structure illustrated in
In the configuration illustrated in
In
Here, the advantages of the second embodiment will be described. In the electronic device 200 according to this embodiment, similarly to the first embodiment, since a countermeasure is taken for all the directions of the noise propagating from the electronic component 201, the leakage of the noise can be prevented. In addition, by including the frequency of the noise generated from the electronic component 201 in the band gap zone of the EBG structure that is configured in accordance with this embodiment, a higher noise suppressing effect can be acquired.
In addition, the connection member 212 as a through via is configured to pass through the conductive body elements 231 and 251 and the metal cap pad 213, the manufacturing process can be shortened. In addition, in an area located on the A layer 210 that is occupied by the connection member 212 passing through it, the metal cap pad 213 is disposed, and accordingly, mounting can be performed while the space is saved. Therefore, the electronic device 200 can be miniaturized.
Furthermore, in the electronic device 200, a noise propagating in the plane direction is configured to pass a plurality of unit cells, and the propagation of electromagnetic waves can be suppressed more effectively.
In addition, the ground plane 281 and the ground plane 271 are connected to the connection member 216 and the connection member 212 so as to have the same electric potentials and serve as the ground of the electronic device 200. Furthermore, in the ground plane 281, an opening through which the connection members 219, 214, 215, 217, and 218 pass is formed and is insulated from the connection members 219, 214, 215, 217, and 218.
Here, the advantages of the third embodiment will be described. In the wiring board 200 according to this embodiment, a noise propagating from the electronic component 201 to the air can be shielded by the metal cap 202. In addition, a noise propagating above the A layer 210, that is, a so-called surface wave can be shielded by the metal cap pad 213 that surrounds the electronic component 201. Furthermore, a noise propagating between the power source plane 241 (or 242 or 243) and the ground plane 281 (first parallel flat plate) can be shielded by the EBG structure that is configured by an area in which a plurality of the conductive body elements 231 and at least one of the power source plane 241 (or 242 or 243) and the ground plane 281 face each other. In addition, a noise propagating between the power source plane 241 (or 242 or 243) and the ground plane 271 (second parallel flat plate) can be shielded by the EBG structure that is configured by an area in which a plurality of conductive body elements 251 and at least one of the power source plane 241 (or 242 or 243) and the ground plane 271 face each other. Furthermore, a noise the leaks from the first parallel flat plate to the second parallel flat plate through the gap 244 or from the second parallel flat plate to the first parallel flat plate can be shielded by the ground plane 271 or the ground plane 281. In other words, in the electronic device 200, since a countermeasure is taken for all the propagation directions of noises propagating from the electronic component 201, the leakage of the noises can be prevented.
By configuring as described above, the conductive body element 121 is located between the metal cap pad 113 and the power source plane 131 and faces the metal cap pad 113. The conductive body element 121 configures a unit cell having the EBG structure of a so-called mushroom type together with the metal cap pad 113, the power source plane 131, and the connection member 122. Described in more detail, the connection member 122 corresponds to the shaft portion of the mushroom and forms inductance. On the other hand, the conductive body element 121 corresponds to a head portion of the mushroom and forms capacitance between the conductive body element 121 and the opposing metal cap pad 113.
The EBG structure of the mushroom type can be represented by an equivalent circuit in which parallel flat plates are shunt with a serial resonance circuit that is configured by the above-described capacitance and the above-described inductance, and the resonant frequency of the above-described serial resonant circuit provides the center frequency of the band gap. Accordingly, by increasing the capacitance by approaching the conductive body element 121 to the opposing metal cap pad 113, the frequency of the band gap zone can be configured to be low. However, even in a case where the conductive body element 121 is not configured to approach the opposing metal cap pad 113, there is no influence on the essential effect of the present invention.
As above, while the embodiments of the present invention have been described with reference to the drawings, the embodiments are examples of the present invention, and various configurations other than those described above may be employed.
For example, in the above-described embodiments, a configuration has been described in which there is one or two layers in which the conductive body elements are arranged, a modified example in which the conductive body elements are arranged in three or more layers may be configured. In addition, while a configuration has been described in which there is a single layer in which the ground plane extends or in which the power source plane extends, a modified example in which at least one of them extends in a plurality of layers may be configured.
Furthermore, in the above-described embodiment, although the ground plane is illustrated in the drawings so as to extend inside of the wiring board, the ground plane may extend to the rear face of the face on which the electronic component is mounted so as to be exposed.
In the second embodiment, although the conductive body elements 231 and 251 are connected to the metal cap pad 213 and the ground plane 271 through the connection member 212, the connection of the conductive body elements 231 and 251 are not limited thereto. For example, the conductive body elements 231 and 251 may be connected to the power source plane 241 (or 242 or 243) or may be connected to another layer.
In addition, it is apparent that the above-described embodiments and modified examples thereof may be combined together in a range in which the contents are not contradictory.
This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2010-051083, filed on Mar. 8, 2010, the entire contents of which are incorporated herein by reference.
Number | Date | Country | Kind |
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2010-051083 | Mar 2010 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2011/000909 | 2/18/2011 | WO | 00 | 9/10/2012 |
Publishing Document | Publishing Date | Country | Kind |
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WO2011/111313 | 9/15/2011 | WO | A |
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6262495 | Yablonovitch et al. | Jul 2001 | B1 |
20100172116 | Yorita et al. | Jul 2010 | A1 |
20100181100 | Nakano et al. | Jul 2010 | A1 |
Number | Date | Country |
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7-263908 | Oct 1995 | JP |
2006-253929 | Sep 2006 | JP |
2007-88102 | Apr 2007 | JP |
2007-165857 | Jun 2007 | JP |
2009-32907 | Feb 2009 | JP |
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Number | Date | Country | |
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20130003333 A1 | Jan 2013 | US |