JP5099322B2 - Photoelectric conversion device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a photoelectric conversion device equipped with a spherical photoelectric conversion element and a method for manufacturing the photoelectric conversion device.

  As a photoelectric conversion device that can be expected to be inexpensive and have high output, a spherical solar cell using a photoelectric conversion element in which an n-type semiconductor layer that is a second semiconductor layer is formed on the surface of a spherical p-type semiconductor that is a first semiconductor. It is being considered. Initially, a method of mounting a spherical element having a diameter of about 1 mm in each of a large number of holes in a support was studied (Patent Document 1, etc.). In recent years, low-concentration spherical solar cells have been proposed in which a spherical element is attached in each recess of a support having a large number of recesses, and the inner surface of the recess functions as a reflecting mirror (Patent Documents 2 to 5). This reduces the amount of expensive silicon used by reducing the thickness of the photoelectric conversion part, and further, by irradiating the element with 4 to 6 times the light directly irradiated by the action of the reflecting mirror, the light is effective. It is intended to be used.

  As this type of photoelectric conversion device and a typical manufacturing method thereof, there are proposals by the present inventors (Patent Documents 3 to 5). The power generation unit of these photoelectric conversion devices includes (1) a plurality of substantially first semiconductors having a spherical first semiconductor and a second semiconductor layer covering the surface of the first semiconductor, and the second semiconductor layer has an opening for exposing the first semiconductor. A spherical photoelectric conversion element; (2) having a plurality of holes for arranging the elements one by one; the second semiconductor layer being electrically connected to an edge of the hole; and an exposed portion of the first semiconductor A conductive support facing the back side, (3) an electrically insulating layer bonded to the back side of the support and having a hole facing at least a part of the exposed portion of the first semiconductor; and (4 ) A metal sheet bonded to the electrical insulation layer and electrically connecting each first semiconductor of the element to each other through a hole in the electrical insulation layer;

  The metal sheet is electrically connected to the first semiconductor of each element by, for example, a conductive paste filled in the holes of the electrical insulating layer and solidified. For example, a power generation unit with an output of around 1 watt is equipped with a large number of about 1800 microelements with a diameter of about 1 mm, and a plurality of such power generation units are appropriately connected in series or in parallel and electrically connected. The battery block is incorporated into the photoelectric conversion device.

  The first semiconductor of each element is connected in parallel to the support constituting the power generation unit, and the second semiconductor layer of these elements is connected in parallel to the metal sheet. When a plurality of such power generation units are connected in series, for example, the support of the adjacent power generation unit and the metal sheet are sequentially connected by welding or the like. For example, in a power generation block in which a plurality of power generation units are connected in series, the support of the power generation unit located at one end serves as a terminal portion on the second semiconductor side of the power generation block and the power generation unit located at the other end. The metal sheet serves as a terminal portion on the first semiconductor side.

  As the support for the power generation unit, a material obtained by processing a conductive material such as aluminum, copper, or nickel is used. As the material of the support, it can be processed with high precision by a press or the like, and further, an alloy layer with silicon is formed by contacting with an element mainly composed of silicon at a high temperature. Aluminum is preferably used because it works effectively to electrically connect the element and the support. As the metal sheet, an aluminum sheet which is usually made of the same material as the aluminum support and can be easily welded by ultrasonic welding or the like is used. However, a sheet made of copper, nickel or the like is also being studied.

  When configuring the photoelectric conversion device, the power generation block is connected to other power generation blocks and other components such as a converter and an external terminal in the photoelectric conversion device. However, since the material of the support and the metal sheet constituting the terminal portions of both poles of a normal power generation block are both aluminum that is difficult to solder, it is difficult to connect with other components by soldering. Moreover, when the material of the connection part of the other party is other than aluminum, or when the connection part is located in a part where welding is difficult, welding with other components is difficult.

Finding effective means for solving the above problems, and making surely and easily electrical and mechanical connection between each component in the photoelectric conversion device is necessary for constructing a highly reliable photoelectric conversion device. It is an indispensable issue.
JP-A-61-124179 JP 2002-50780 A JP 2002-164554 A JP 2004-63564 A US2006 / 0185716A1

  The present invention includes a plurality of substantially spherical photoelectric conversion elements each having a spherical first semiconductor and a second semiconductor layer covering the surface thereof, the second semiconductor layer having an opening through which the first semiconductor is exposed. A support mainly composed of aluminum or an aluminum alloy that supports and is electrically connected to the first semiconductor or second semiconductor layer of the element, and is electrically connected to the second semiconductor layer or first semiconductor of the element A power generation unit including a metal sheet mainly composed of aluminum or an aluminum alloy, and an electrical insulating layer that insulates the support and the metal sheet, or a power generation block in which a plurality of the power generation units are electrically connected. The present invention relates to an improvement in a photoelectric conversion device and a manufacturing method thereof.

  The problem to be solved by the present invention is to improve the terminal structure of the power generation block incorporated in the photoelectric conversion device in the photoelectric conversion device and the manufacturing method thereof, and solve the problems related to the connection with the other components. It is to be. Accordingly, an object is to provide a highly reliable photoelectric conversion device.

The photoelectric conversion device of the present invention includes a plurality of substantially spherical photoelectric semiconductors, each having a spherical first semiconductor and a second semiconductor layer covering the surface thereof, the second semiconductor layer having an opening through which the first semiconductor is exposed. Conversion element,
A support mainly composed of aluminum or an aluminum alloy that supports the photoelectric conversion element and is electrically connected to the first semiconductor or the second semiconductor layer of the photoelectric conversion element;
A metal sheet mainly composed of aluminum or an aluminum alloy electrically connected to the second semiconductor layer or the first semiconductor of the photoelectric conversion element; and
An electrical insulating layer for insulating the support and the metal sheet;
A photoelectric conversion device comprising a power generation block consisting of a plurality of power generation units that are electrically connected to each other or a power generation unit comprising:
A terminal plate is connected to each of the support of the power generation unit located at one end of the power generation block and the metal sheet of the power generation unit located at the other end, and each terminal plate is a base sheet made of aluminum or an aluminum alloy And a metal layer mainly composed of at least one selected from the group consisting of copper, brass, tin, iron, silver, and solder, which is bonded to one side of the base sheet. The material sheet side is welded to each of the support and the metal sheet.

  Since the support and the metal sheet constituting the power generation unit of the present invention are both made of substantially the same material mainly composed of aluminum or aluminum alloy, for example, when producing a power generation block in which a plurality of power generation units are connected in series. In addition, it is possible to easily and reliably connect between the support of the adjacent power generation unit and the metal sheet by ultrasonic welding or the like. The basic feature of the present invention is that a terminal plate to be attached to both ends of the power generation block is obtained by bonding a metal layer, at least the surface of which is easily soldered, to one side of a base sheet made of aluminum or an aluminum alloy. The terminal portion is configured by welding the base sheet side of the terminal plate to each of the support and the metal sheet.

  In this way, the terminal plate can be easily formed by welding the base sheet made of aluminum or aluminum alloy of substantially the same material to the support and the metal sheet as the terminal portions at both ends of the power generation block by ultrasonic welding or the like. It is possible to connect to the power generation block reliably and reliably. In addition, the other surface of the terminal board is a metal that is easy to solder, mainly composed of at least one selected from the group consisting of brass, tin, iron, silver, and solder, so that the power generation block, converter, external terminal, etc. Connection with other components in the photoelectric conversion device can be reliably and easily performed by soldering. This makes it easy to solder to the connected part on the other side, which is difficult to weld with aluminum or aluminum alloy, or to the connected part located away from the power generation block via appropriate wiring. In addition, it is possible to easily and reliably connect the power generation blocks to each other and to other components in the photoelectric conversion device.

  According to the present invention, highly reliable photoelectric conversion in which electrical generation and mechanical connection between the power generation block and other components in the photoelectric conversion device are reliably performed as well as connection between the power generation units in the power generation block. An apparatus can be provided.

The present invention is an improvement of the structure of the terminal portion of the power generation block to which a single power generation unit or a predetermined number of power generation units incorporated in the photoelectric conversion device is connected,
The support of the power generation unit located at one end of the power generation block and the metal sheet of the power generation unit located at the other end are each provided on one side of the base sheet with the metal layer at least on the surface being easily soldered. It is connected to the base sheet side of the terminal board formed on the base plate, and the main material of the support and the metal sheet and the base sheet are both made of aluminum or an aluminum alloy.

  In the present invention, the easily solderable metal layer formed on one side of the terminal board is mainly composed of at least one selected from the group consisting of copper, brass, tin, iron, silver, and solder. More preferably, the terminal plate comprises a clad plate of a copper sheet as a metal layer that is easy to solder and a base sheet made of aluminum or an aluminum alloy. Further, the terminal plate is more preferably a clad plate obtained by sequentially laminating a base sheet, a copper sheet, and a solder sheet, or a copper plate side of the clad plate of the base sheet and the copper sheet. . It is preferable that the terminal board has a thickness of 100 to 300 μm, the base sheet has a thickness of 50 to 200 μm, and the metal layer that can be easily soldered has a thickness of 50 to 100 μm.

  The support in the present invention regularly has a large number of holes for mounting the elements at predetermined positions. It is preferable to form a recess having a hole for mounting an element in the bottom so that the surface of the support can be used as a reflecting mirror. Since the support also serves as a conductor that is electrically connected to the second semiconductor layer of the element, at least the surface side, and in the preferred embodiment, the side that becomes the light receiving surface needs to have conductivity. Since a large number of elements having a small diameter of, for example, 1 mm in diameter are mounted on the support at a high density at a predetermined position, the support body is required to have extremely high shape and dimension accuracy. Therefore, in the present invention, aluminum or an alloy containing aluminum as a main component is used as a material capable of producing a highly accurate support by press working or the like. If a surface layer of silver or the like having excellent reflectivity and conductivity is formed on the light receiving surface by plating, sputtering or vacuum deposition, the function as a reflector and a conductor is enhanced, and the output of the photoelectric conversion device is increased. Can do.

  The support is usually produced by pressing a sheet of aluminum or aluminum alloy having a thickness of 100 to 500 μm. FIG. 1 shows a typical support by the above press working. The recesses 21 of the support 20 are narrower toward the bottom, their open ends 23 are hexagonal and adjacent to each other, and the holes 22 formed in the bottom are smaller than the outer diameter of the element.

  As a material for the metal sheet electrically connected to the first semiconductor of each element, a sheet made of aluminum or an alloy containing aluminum as a main component is used as in the case of the support. If a metal sheet in which a layer of silver, copper, nickel or the like having excellent conductivity is formed on at least one surface of this sheet by plating, sputtering, vacuum deposition or the like is used, the function as a conductor on the first semiconductor side Can be increased. Usually, the thickness of the metal sheet is preferably 15 to 100 μm. As the metal sheet, a porous sheet may be used instead of the non-porous sheet.

  As described above, the material of the base material sheet of the support, the metal sheet, and the terminal plate is the same or substantially the same, thereby connecting the metal sheet and the support of the adjacent power generation unit when configuring the power generation block. And the terminal plates to both ends of the power generation block can be easily and firmly connected by welding. Aluminum or aluminum alloy, which is the main material of each of the above members, is a solder because it easily forms a tough oxide film on the surface in the atmosphere, has a low melting point and a large thermal expansion coefficient, and is difficult to dissolve in solder. It is difficult to attach. Therefore, in order to bond these members to each other, it is particularly necessary to join the surfaces of both members with the oxide film removed, and ultrasonic welding is suitable as the welding method.

  In ultrasonic welding, both surfaces of the members to be joined are overlapped, and by applying initial vibration while applying pressure, the oxide film is destroyed and scattered, until a predetermined oscillation time or predetermined energy is reached. Continue to vibrate to complete joining (welding). Usually, the bonding is performed at a temperature equal to or lower than the melting point. However, when members of the same material are bonded to each other as in the present invention, they can be bonded firmly at a lower temperature. In addition to ultrasonic welding, resistance welding such as spot welding can also be employed, but ultrasonic welding that is excellent in terms of bond strength and electrical resistance of the joint and that can weld a large area by a single welding operation is more preferable.

  Aluminum and aluminum-based alloys used as the main material for the above support, metal sheet, and terminal board base sheet are not particularly limited in their types, but weather resistance, strength, weldability, and workability What is excellent in is preferable. There are various types of aluminum alloys, but in general, alloys such as Al—Mn and Al—Mg are suitable in terms of workability and corrosion resistance. In particular, when a foil-like thin sheet having a thickness of about 200 μm or less is used, for example, those specified in “aluminum and aluminum alloy foil” of JIS H4160 can be preferably used. As typical materials for these foils, there are aluminum alloys defined by JIS IN30 and JIS 8021, and the addition rate of Fe is appropriately adjusted with an upper limit of about 2%.

  Although the structure of the power generation unit in the present invention is various, a typical power generation unit has the plurality of substantially spherical photoelectric conversion elements and a plurality of holes for arranging the elements one by one. A support mainly composed of aluminum or an aluminum alloy, the second semiconductor layer of which is electrically connected to the edge of the hole and the exposed portion of the first semiconductor faces the back side, on the back side of the support An electrically insulating layer having a hole in at least a part of a portion opposed to the exposed portion of the first semiconductor, and the first semiconductor of each of the plurality of elements connected to the electrically insulating layer. It comprises a metal sheet mainly composed of aluminum or an aluminum alloy that is electrically connected to each other through holes.

  The photoelectric conversion element in the present invention preferably has an antireflection film covering the surface of the second semiconductor layer, and the second semiconductor layer and the antireflection film each have an opening for exposing the first semiconductor at the same site. . Furthermore, it is preferable that the support has a concave portion having the hole at the bottom adjacent to the surface, and has a reflecting mirror layer on the inner surface of the concave portion.

The manufacturing method of the photoelectric conversion device of the present invention is an effective manufacturing method for efficiently manufacturing the photoelectric conversion device according to the present invention,
(A) A plurality of substantially spherical photoelectric conversion elements each having a spherical first semiconductor and a second semiconductor layer covering the surface thereof, the second semiconductor layer having an opening exposing the first semiconductor, and supporting the element And a support mainly composed of aluminum or an aluminum alloy electrically connected to the first semiconductor or second semiconductor layer of the element, and aluminum electrically connected to the second semiconductor layer or first semiconductor of the element Or preparing a plurality of power generation units comprising a metal sheet mainly composed of an aluminum alloy, and an electrical insulating layer that insulates the support and the metal sheet;
(B) a step of electrically connecting a plurality of the power generation units in series or in parallel to each other by welding the ends of the power generation units and / or metal sheets;
And (c) a base sheet made of aluminum or an aluminum alloy on each of the support of the power generation unit located at one end of the plurality of connected power generation units and the metal sheet of the power generation unit located at the other end And a terminal board having a metal layer mainly composed of at least one selected from the group consisting of copper, brass, tin, iron, silver, and solder, which is bonded to one side of the base sheet. Welding the base sheet side of
It is characterized by including.

  The photoelectric conversion element in the present invention will be described in detail. The spherical first semiconductor that constitutes the core of the element is formed by, for example, melting a p-type polycrystalline silicon lump containing a very small amount of boron supplied in a crucible in an inert gas atmosphere. It can be manufactured by cooling and solidifying while naturally falling from a minute nozzle hole at the bottom of the crucible. The first semiconductor is a polycrystalline or single crystal p-type semiconductor. Usually, after polishing the surface and further removing about 50 μm of the surface layer by etching or the like, it is used as a spherical first semiconductor.

  The p-type first semiconductor is heat-treated at 800 to 950 ° C. for 10 to 30 minutes using, for example, phosphorus oxychloride as a diffusion source, so that the second semiconductor layer, that is, the n-type semiconductor layer has a thickness of about A phosphorus diffusion layer of about 0.5 μm is formed. Contrary to the above element, the first semiconductor may be an n-type semiconductor and the second semiconductor layer may be a p-type semiconductor layer. The first semiconductor may be one in which the first semiconductor layer is coated on the outer peripheral surface of the core body, or the one near the center may be hollow. The first semiconductor is preferably a true sphere, but it may be substantially spherical. The diameter of the first semiconductor is usually 0.5 to 2 mm, preferably 0.8 to 1.2 mm.

  In addition to a crystalline silicon semiconductor as a main component, the photoelectric conversion element may be made of a compound semiconductor or the like, or may be made of an amorphous material. The device has a pin type structure in which a non-doped layer is formed at the interface between the first semiconductor and the second semiconductor layer, a MIS type, a Schottky barrier type, a homojunction type, or a heterojunction type. May be.

  An element 10A in which the second semiconductor layer 2 is formed on the surface of the first semiconductor 1 is shown in FIG. An element 10B in which the opening 4 is formed in the second semiconductor layer 2 is shown in FIG. The second semiconductor layer 2 and the first semiconductor 1 are partially cut away to form an exposed portion 3 of the first semiconductor. FIG. 2C shows an element 10C in which the conductive layer 6 is formed on the exposed portion 3 of the first semiconductor. FIG. 3 shows an element in which an antireflection film 5 is formed on the second semiconductor layer 2. FIG. 3A corresponds to the element of FIG. 2A, and if this is processed, an element as shown in FIGS. 3B and 3C can be obtained. The conductive layer 6 in FIGS. 2C and 3C is formed, for example, by applying a conductive paste to the exposed portion 3 of the first semiconductor and performing a heat treatment at a high temperature.

  As the conductive paste for forming the conductive layer, a conductive paste containing a conductive material made of a metal such as silver, gold, copper, nickel, or an alloy thereof, a binder, and a solvent or dispersion medium can be used. In the case where the first semiconductor is p-type, those containing respective additives such as aluminum powder and in the case of n-type are preferable. By the heat treatment after the coating, a layer rich in ohmic conductivity with the first semiconductor is formed on the bonding surface side of the conductive layer with the first semiconductor. The conductive layer is formed as an alloy layer or a diffusion layer of the additive in the conductive paste and silicon on the surface of the first semiconductor, and electrically connects the first semiconductor and the metal sheet with low resistance. Works effectively to connect to.

As the antireflection film of each element of FIG. 3, for example, a thin film mainly composed of ZnO, SnO ₂ or ITO (In ₂ O ₃ —SnO ₂ ) formed by a solution deposition method, an atomization method or a spray method is used. Can be applied. In many cases, the antireflection film preferably has conductivity because the second semiconductor layer and the support are electrically connected to each other via the antireflection film. In particular, a conductive SnO ₂ film having a thickness of 50 to 100 nm doped with at least one of fluorine and antimony is preferable. For example, a large number of elements on which a second semiconductor layer is formed are heated on a heating plate to 400 to 600 ° C., and doped materials such as ammonium fluoride, hydrofluoric acid, antimony pentachloride or antimony trichloride, and tin tetrachloride. By spraying fine particles of a solution of a tin compound such as dimethyltin dichloride or trimethyltin chloride onto the element, a conductive SnO ₂ film having a substantially constant thickness is formed on the surface.

  Examples of the electric insulating sheet for forming the electric insulating layer include a thermosetting resin such as an epoxy resin, and a thermoplastic resin sheet such as polycarbonate, polytetrafluoroethylene, thermoplastic polyimide, and polyetheretherketone. Or a film can be used. A particularly preferable electrical insulating sheet is a semi-cured resin sheet, for example, a thermosetting resin such as a semi-cured epoxy resin or a sheet mainly composed of this, and a semi-cured state on both surfaces of other resin sheets. There is a sheet on which a thermosetting resin layer is formed.

  These semi-cured resin sheets are imparted with appropriate flexibility and tackiness by heating during thermocompression bonding to the back surface of the support and are firmly adhered to the support. Furthermore, the two are firmly adhered to each other by heating and pressurizing during thermocompression bonding when the metal sheet is bonded to the resin sheet. If the resin sheet is cured by further heating while applying pressure, the support and the metal sheet can be firmly bonded via the resin sheet without using an adhesive.

Next, embodiments of the photoelectric conversion device and the manufacturing method thereof according to the present invention will be specifically described for each process.
1) Step of preparing a power generation unit In this step, a power generation unit to be incorporated into a photoelectric conversion device is prepared. The power generation unit in the present embodiment is a power generation unit of the above representative form, and includes a spherical first semiconductor and a second semiconductor layer covering the surface thereof, and the second semiconductor layer exposes the first semiconductor. A plurality of substantially spherical photoelectric conversion elements having openings; a plurality of holes for arranging the elements one by one; a second semiconductor layer electrically connected to an edge of the holes; A support mainly composed of aluminum or an aluminum alloy with the exposed portion of the semiconductor facing the back surface, a hole bonded to the back surface of the support and facing the exposed portion of the first semiconductor. Electrical insulating layer and metal sheet mainly formed of aluminum or aluminum alloy formed on the electrical insulating layer and electrically connecting each first semiconductor of the element to each other through holes of the electrical insulating layer It is provided.

  According to the configuration method of the power generation unit, depending on the form of the element used at the stage of mounting on the support, (b) when using the element of FIG. 2 (a) or FIG. 3 (a), (b) FIG. When the element of FIG. 3B is used, and (c) when the element of FIG. 2C or FIG. Below, those typical embodiments are described in detail.

1)-(I)
In this embodiment, first, for example, an assembly in which the element 10A of FIG. 2A is fixed to the hole portion of the support of FIG. 1 is prepared. In the assembly 30A shown in FIG. 4, the second semiconductor layer 2 of the element 10A is connected to the edge of the hole of the recess of the support 20 by the conductive adhesive 24, and a part of the element 10A is the back surface of the support 20 Facing the side. FIG. 4 shows only a part of the support corresponding to the cross-sectional view taken along the line IV-IV in FIG. The size of the support is 50 × 150 mm, and about 1800 elements are arranged.

The conductive adhesive 24 is applied in a ring shape around the periphery of the hole of the support. The assembly 30A is configured by placing elements on a support and heating to solidify the adhesive before the applied adhesive dries. As the conductive adhesive, a conductive paste containing a conductive material such as silver, aluminum, copper, or nickel, a binder, and a solvent or dispersion medium can be used.
When the element shown in FIG. 3A, in which the second semiconductor layer is coated with the antireflection film, is fixed to the support, the second semiconductor layer is made of a conductive adhesive through the conductive antireflection film. It is electrically connected to the support.

  Next, the exposed portion 13 of the first semiconductor is formed in the element 10 at the part facing the back surface side of the support 20 of the assembly 30A (FIG. 5A). Specifically, the surface layer (thickness: about 1 to 3 μm) of the element is removed by etching, mechanical polishing such as sand blasting or brushing, or a combination thereof. The surface layer to be removed may be a layer on the surface of the first semiconductor and the second semiconductor layer formed thereon, or may include an antireflection film formed thereon.

  A conductive layer is preferably formed on the exposed portion 13 of the first semiconductor. First, the conductive paste for forming the conductive layer is applied to the exposed portion 13 of the first semiconductor to form a coating layer having a diameter of about 300 μm and a thickness of about 50 μm. Next, the conductive layer 16 is formed by irradiating the coating layer with a YAG laser (FIG. 5 (2)). By this laser irradiation, a high temperature heat treatment is locally performed, and an alloy layer of silicon on the exposed surface of the first semiconductor and aluminum in the paste is formed. Since this alloy layer is rich in ohmic conductivity with the first semiconductor, it contributes to low-resistance electrical connection between the first semiconductor and the metal sheet. The conductive layer is a thin layer mainly composed of the above alloy layer.

  A coating layer of a conductive paste is preferably formed on the exposed portion of the first semiconductor or the conductive layer in order to easily open a hole in the electrical insulating layer by laser irradiation in a later step. As the conductive paste, one containing at least one conductive material of silver, copper, nickel and gold can be used. When the diameter of the exposed portion of the first semiconductor is 0.4 to 0.7 mm, the diameter of the coating layer is preferably 0.2 to 0.5 mm and the thickness is preferably 50 to 100 μm. FIG. 5 (3) shows a state in which a conductive paste coating layer 7 is formed on the conductive layer 16 in FIG. 5 (2). The conductive layer 16 alone has the function of an electrode. However, as described above, both the conductive layer 16 and the conductive paste coating layer 7 can also function as an electrode. The conductive paste coating layer 7 is preferably solidified by heating.

  Next, an electrical insulating layer is bonded to the back surface of the support. The typical embodiment is a method of attaching a resin sheet made of a semi-cured epoxy resin to the back surface of the support. For example, the resin sheet 40 is lightly pressed and temporarily fixed to the back surface of the support 20 of the assembly shown in FIG. 5 (3), and then pressed between two hot plates. Thereby, the resin sheet 40 is affixed on the back surface of the support body 20 (FIG. 6 (1)). In addition to the method using a resin sheet, a resin layer formed by applying a resin paste to the back surface of a support and drying can be used as an electrical insulating layer. As the resin paste, one obtained by dissolving or dispersing a polyimide resin, a silicone resin, a urethane resin, an acrylic resin, or the like in an organic solvent or water is used.

  Next, by irradiating the electrical insulating layer in a region where at least a part of the exposed portion of the first semiconductor opposes, a hole is formed in the electrical insulating layer in the region. Since the carbon dioxide laser has a high reflectivity for metals such as silver contained in the conductive paste coating layer, if this coating layer is formed as an underlayer for the electrical insulating layer, the laser energy is concentrated at the irradiated site. Absorbed. Thereby, the hole of a predetermined dimension shape can be opened more correctly in a predetermined position. This hole becomes a conductive path for connecting the first semiconductors of the respective elements to each other in a later step.

  FIG. 6 (2) shows a process of making a hole in the electrical insulating layer of the assembly of FIG. 6 (1). A portion of the resin sheet 40 facing the conductive paste coating layer 7 is irradiated with the laser 12 by the carbon dioxide laser irradiation device 11. As a result, a hole 42 having a diameter of about 0.3 mm that penetrates the resin sheet 40 having a thickness of 75 μm is formed, and the conductive paste coating layer 7 is exposed inside the hole 42.

  Next, the power generation unit is completed by electrically connecting the metal sheet bonded to the back surface of the electrical insulating layer and the first semiconductor of each element fixed to the support through the holes of the electrical insulating layer. A typical embodiment is a method of bonding a metal sheet to an electrical insulating layer after filling a conductive path in a conductive path.

  First, the hole is filled with the conductive paste 55 in a slightly larger amount than the hole 42 of the resin sheet 40 of the assembly shown in FIG. 6 (2) (FIG. 7 (1)). As the conductive paste, the same conductive adhesive as that used for fixing the element to the support can be used. Next, the aluminum sheet 75 is superposed on the semi-curable resin sheet 40 and thermocompression bonded, and then heat-treated to solidify the conductive paste 55 and simultaneously cure the resin sheet (FIG. 7 (2)). Thereby, the aluminum sheet 75 is firmly joined to the resin sheet 40, and the first semiconductor 1 and the aluminum sheet 75 are reliably electrically connected. In accordance with this method, a power generation unit using the element of FIG. 3A in which the second semiconductor layer 2 is covered with the antireflection film 5 can also be configured.

  When the conductive paste filled in the conductive path is heated, vaporized components due to volatilization or thermal decomposition of organic solvent and resin in the paste are interposed between the electrical insulating layer and the metal sheet, and the bonding or 1 The electrical continuity between the semiconductor and the metal sheet may become unstable. In order to prevent this, a metal sheet provided with a large number of vent holes may be bonded to the electrical insulating layer so that at least a part of the vent holes faces each conductive path.

  Next, as another embodiment, a method of providing holes communicating with each other in each of the electrical insulating layer and the metal sheet, filling the two holes with a conductive paste, and solidifying will be described. For example, first, an aluminum sheet 35 having a hole 44 at a position corresponding to the hole of the support is attached to the resin sheet 40 of the assembly shown in FIG. 6A (FIG. 8A). Next, the laser beam 15 is irradiated into the hole 44 of the aluminum sheet to open a hole 52 in the resin sheet 40 at that portion (FIG. 8 (2)). Next, the hole 52 of the resin sheet is filled with the conductive paste 55 and solidified (FIG. 8 (3)). Thereby, the first semiconductor of each element is electrically connected to the aluminum sheet. As an embodiment similar to FIG. 8 (3), for example, an electrical insulating layer and an aluminum sheet are sequentially bonded to the back surface of the support, or a composite sheet in which both are integrated is bonded to the back surface of the support, and then both It is also possible to adopt a method of forming a hole that communicates, and filling the hole with a conductive paste to solidify.

  In any of the above methods, the metal sheet and the first semiconductor are electrically connected using the solidified conductive paste as the interlayer connection, but the conductor bump formed on the first semiconductor side is used as the interlayer connection. You can also. For example, conical conductor bumps are formed on the conductive layer 16 on the exposed portion 13 of the first semiconductor of the assembly shown in FIG. The conductive bump is formed by applying a conductive paste having a relatively high viscosity on a conductive layer using a thick metal mask, and heating and solidifying the conductive paste. The tip of the conductor bump is tapered, and a thickness of about 100 to 300 μm sufficient to contact the metal sheet is preferable.

  Next, the resin sheet 40 is superposed on the back surface of the support 20 and pressed, and the two are bonded together, and the leading end portion of the conductor bump 8 is penetrated from the resin sheet 40 (FIG. 9 (1)). Furthermore, the aluminum sheet 45 is superposed on the resin sheet 40 and pressed to bond them together, and the tip of the plastically deformed conductor bump 8 is brought into contact with the aluminum sheet 45 (FIG. 9 (2)). Accordingly, the aluminum sheet and the first semiconductor of each element are electrically connected using the conductor bump as an interlayer connection portion.

1)-(b)
A representative embodiment of a method for forming a power generation unit using the element shown in FIG. 2B or FIG. 3B in which an opening for exposing a part of the first semiconductor is formed in the second semiconductor layer. Will be described with reference to FIG.

  First, in accordance with the configuration method of the assembly 30A in FIG. 4, the element shown in FIG. 2B is fixed to the support 20 in which the conductive adhesive 24 is applied to the edge of the hole (FIG. 10 (1)). . The element 10B is aligned and fixed so that the exposed portion 3 of the first semiconductor 1 faces the back side of the support 20. Next, the resin sheet 70 is bonded to the back surface of the support 20 in accordance with the method of Fig. 6, and a hole 72 serving as a conductive path is formed in the resin sheet 70 ((2) in Fig. 10). 1 A conductive paste is applied to the exposed portion 3 of the semiconductor, and this is irradiated with a laser to form a conductive layer 76 by a method according to FIG. 5 (2) ((3) in FIG. 10). 7 (1), the aluminum sheet 75 is attached to a resin sheet filled with a slightly larger amount of the conductive paste 85 than the hole 72 is filled, and then the conductive paste 85 is solidified ((FIG. 10 (4) )).

1)-(C)
About the method of forming the power generation unit of step (a) using the element shown in FIG. 2C or FIG. 3C in which the exposed portion of the first semiconductor is formed and the conductive layer is further formed in the exposed portion. A representative embodiment will be described with reference to FIG.

  First, according to the method of constructing the assembly 30A of FIG. 4, the element of FIG. 2C is fixed to the support 20 in which the conductive adhesive 24 is applied to the edge of the hole (FIG. 11 (1)). ). At this time, the element 10 </ b> C is aligned and fixed so that the exposed portion 3 of the first semiconductor 1 and the conductive layer 6 face the back side of the support 20. Next, in accordance with the method of Fig. 6, the resin sheet 70 is bonded to the back surface of the support 20, and a hole 62 serving as a conductive path is formed in the resin sheet 70 ((Fig. 11 (2)). According to the method, after the aluminum sheet 75 is attached to the resin sheet 70 filled with a slightly larger amount of the conductive paste 65 than the hole 62 is filled, the conductive paste 65 is solidified ((3) in FIG. 11).

  In the above 1)-(b) or 1- (c), a power generation unit is formed using the element shown in FIG. 3B or 3C in which the second semiconductor layer is covered with a conductive antireflection film. Also in the case of the configuration, the same method as in FIG. In these cases, an antireflection film is interposed between the second semiconductor layer and the edge of the support. Moreover, according to the process in the various embodiment of 1)-(b), its procedure, and the structure of the power generation unit, various types of 1)-(b) or 1- (c) other than FIG. 10 and FIG. Embodiments can be taken.

Further, in each of the above embodiments, a preferred mode is adopted in which a conductive layer is formed on the exposed portion of the first semiconductor, or a coating layer of a conductive paste is formed thereon. However, the conductive layer and the coating layer of the conductive paste are not necessarily required.
In the power generation unit thus obtained, the spherical photoelectric conversion element is firmly fixed in the hole of the support, and further, the first semiconductor and the metal sheet of all the elements fixed to the support, and the second semiconductor layer, The support is reliably electrically connected to the support.

2) Step of configuring a power generation block composed of a plurality of power generation units The power generation block incorporated in the photoelectric conversion device may be composed of a single power generation unit or a plurality of power generation units. Since the former is the power generation unit 1) itself, the description thereof will be omitted, and the latter embodiment will be described below.

  A power generation block composed of a plurality of power generation units is usually configured by electrically connecting a predetermined number of power generation units in series, but may be configured by connecting them in parallel. The support of the power generation unit includes a support part that supports a predetermined number of photoelectric conversion elements and a flange part that surrounds the support part. A portion of the support on one side of the collar and a portion of the aluminum sheet exposed on the back surface of the collar facing the collar serve as a connecting portion of each power generation unit, thereby forming the power generation block.

An example in which a power generation block in which a plurality of power generation units are connected in series will be described below.
FIG. 12 is a plan view of the power generation unit of FIG. 8 (3) as viewed from the support side. FIG. 13 shows a state in which two adjacent power generation units are connected in a power generation block composed of a plurality of power generation units. About 1800 photoelectric conversion elements 10 having a diameter of about 1 mm are fixed to the recesses 21 of the support portion 30 of the support 20. The size of the power generation unit 100 is 50 × 150 mm, and the edge portions 103 and 104 on the short side are composed of three layers of the support 20, the resin sheet (electrical insulating layer) 40, and the aluminum sheet 35. At one edge 101 on the long side, the end of the aluminum sheet 35 protrudes outside the ends of the support 20 and the electrical insulating layer 40. At the other edge 102, the end of the support 20 protrudes outside the ends of the electrical insulating layer 40 and the aluminum sheet 35.

  A plurality of such power generation units are overlapped with their edges 101 and 102 and connected to each other by welding such as ultrasonic welding or spot welding, thereby generating a power generation block in which the power generation units are connected in series. Can be configured. Although there is no restriction | limiting in the number of the power generation units which comprise a power generation block, Usually, it is comprised from less than 30 power generation units. For example, as shown in FIG. 13, the back side (electrical insulating layer side) of the aluminum sheet 35A exposed at the edge 101A of one power generation unit 100A and the support exposed at the edge 102B of the other power generation unit 100B. In the place where the back side of the body 20B is overlapped, both are connected by ultrasonic welding. Instead of the connection method of FIG. 13, the surface side of the support 20 </ b> A and the surface side of the aluminum sheet 35 </ b> B may be overlapped at the edge of the long side of each power generation unit, and both may be connected by welding.

  The support and the metal sheet in the present invention are mainly composed of aluminum or an alloy containing aluminum as a main component, and a surface layer such as silver may be provided on one side thereof. In the above case, it is preferable to superimpose the surfaces on which the surface layer is not formed (surfaces on which aluminum or aluminum alloy is exposed) and weld them by ultrasonic welding or the like using the same material for both joint surfaces. .

  For example, a silver surface layer may be formed on the surface side (light-receiving surface side) of the support as described above. In addition, as shown in FIG. 8, when the metal sheet is electrically connected to the first semiconductor through the hole by the conductive paste, silver or copper is used on the surface side of the metal sheet (opposite to the light receiving surface). A thin surface layer may be formed. When such a surface layer is formed on a support or a metal sheet, for example, by adopting a connection method as shown in FIG. 13, the back surface of the support to be joined and the back surface of the metal sheet are both made of the same material ( Since both are made of aluminum or an aluminum alloy, both are more firmly connected.

  In the above, an example in which a plurality of power generation units are connected in series has been shown, but a power generation block in which a plurality of power generation units are connected in parallel is formed by welding the supports and metal sheets of adjacent units. You can also

3) A step of connecting an easily soldered terminal board to the power generation block.
In this step, each of the power generation unit support positioned at one end and the metal sheet of the power generation unit positioned at the other end of the power generation block configured by connecting a plurality of power generation units alone or at each power generation unit Connect the terminal board to. The terminal plate includes a base sheet made of aluminum or an aluminum alloy, and a metal layer that is bonded to one side of the base sheet and at least the surface of which is easily soldered. Are connected to the connected surface on the power generation block side by welding.

Since the base sheet of the terminal plate in the present invention is the same material as the main material of the metal sheet and the support as described above, the base sheet side of the terminal plate is ultrasonically applied to the connected portion of the support and the metal sheet. If welding is performed, the terminal plate can be firmly connected to the power generation block.
As described above, the metal layer that is easily soldered and formed on one side of the base sheet in the terminal board is selected from the group consisting of copper, brass, tin, iron, silver, and solder. It is made of a metal mainly composed of at least one kind. This metal layer and other components in the photoelectric conversion device are connected by soldering. When the surface layer is solder, it is preferable that the solder layer is formed on at least a part of the layer containing the above metal other than solder as a main component.

As the terminal board, i) one side of the above-mentioned base sheet is bonded with a metal layer other than solder that is easy to solder, ii) soldering via an intermediate layer formed on one side of the above base sheet Bonded metal layer other than solder that is easy to solder, and solder layer bonded or partially adhered to a metal layer other than solder that is easy to solder in i) or ii) , Etc. can be used. In many cases, soldering with other components can be easily performed by previously forming a solder layer on the terminal board as described above or by partially attaching solder. Ii above
In order to facilitate the formation of a metal layer that can be easily soldered, such as copper, by plating or the like, the intermediate layer in (1) is formed on the surface of the base sheet by sputtering or plating as necessary. , Cr, Ni, Ni-P, Ni-B and other underlayers.

  When a solder layer is provided in advance as a metal layer on which the terminal board can be easily soldered, the thickness is preferably 10 to 100 μm. When a metal layer other than solder that is relatively easy to solder is required, a clad plate in which a metal sheet such as copper is bonded to a base sheet rather than forming the metal layer by sputtering or plating Is effective. A clad plate having a three-layer structure in which a solder sheet is bonded to the clad plate, or a plate obtained by performing solder plating is more effective as a terminal plate. There are no particular limitations on the type of solder, but due to recent demands related to environmental problems, Sn-Ag-Cu-based, Sn-Bi-Ag-based, etc. lead-free solder containing Sn or Bi as the main component is used. It is preferable to use it.

  14 is a plan view of a state in which the terminal plate according to the present invention is attached to the power generation block of FIG. 13 as viewed from the light-receiving surface side, and FIG. 15 is a longitudinal sectional view showing the state of the terminal plate and its attachment portion in FIG. FIG. In this power generation block, for example, 20 power generation units 100 are connected in series, and the structure of the connecting portion 110 between the power generation units is as shown in FIG. The back surfaces of the end portion 20C of the support of the power generation unit 100C located at one end and the end portion 35D of the metal sheet of the power generation unit 100D located at the other end are separated from the clad plates of the aluminum sheet 121 and the copper sheet 122, respectively. The terminal plate 120 is welded to the aluminum sheet 121 side.

  A single or a plurality of power generation blocks to which the terminal plate is attached as described above are electrically connected in series or in parallel as appropriate according to the specifications, and are incorporated as power generation elements of the photoelectric conversion device. At this time, since the terminal board that is easy to solder and the connected portion of the other component in the apparatus can be firmly connected by soldering, each power generation block and other components in the photoelectric conversion device The mechanical and electrical connection can be reliably performed. Thereby, a highly reliable photoelectric conversion device can be provided.

  The photoelectric conversion device according to the present invention is particularly useful as a solar cell for private power generation in a building such as a house.

It is a top view of the principal part which shows an example of the support body used for this invention. It is a longitudinal cross-sectional view which shows the aspect of the photoelectric conversion element used for this invention. It is a longitudinal cross-sectional view which shows another aspect of the photoelectric conversion element used for this invention. It is a longitudinal cross-sectional view which shows the process of the 1st step in the manufacture process of the electric power generation unit of 1st Embodiment in this invention. It is a longitudinal cross-sectional view which shows the process of the 2nd step in a manufacturing process same as the above. It is a longitudinal cross-sectional view which shows the process of the 3rd step in a manufacturing process same as the above. It is a longitudinal cross-sectional view which shows the process of the last stage in a manufacturing process same as the above. It is a longitudinal cross-sectional view which shows the manufacturing process of the electric power generation unit of 2nd Embodiment same as the above. It is a longitudinal cross-sectional view which shows the manufacturing process of the electric power generation unit of 3rd Embodiment same as the above. It is a longitudinal cross-sectional view which shows the manufacturing process of the electric power generation unit of 4th Embodiment same as the above. It is a longitudinal cross-sectional view which shows the manufacturing process of the electric power generation unit of 5th Embodiment same as the above. It is a top view of the electric power generation unit of 2nd Embodiment same as the above. It is principal part sectional drawing which shows the connection part of the electric power generation units in one Embodiment of the electric power generation block in this invention. It is a top view of the electric power generation block which attached the terminal board by this invention. It is principal part sectional drawing of the electric power generation block which attached the terminal board by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st semiconductor 2 2nd semiconductor layer 3, 13 Exposed part of 1st semiconductor 4 Opening part of 2nd semiconductor layer 5 Antireflection film 6.16 Layer which has ohmic conductivity with 1st semiconductor 7 Conductive paste Coating layer 8 Conductive bump 10, 10A, 10B, 10C Photoelectric conversion element 15 Laser 20, 20B, 20C Support 21 Recess 22 (Support) hole 24 Conductive adhesive 35, 45, 75, 35A, 35D Metal sheet 40 , 70 Electrical insulating sheet (or resin sheet)
44 Metal sheet holes 52, 62 Electrical insulation layer holes (conducting paths)
55, 65 Conductive paste 100, 100A, 100B, 100C, 100D Power generation unit 101, 101A The other edge 102 on the long side of the power generation unit 102, 102B The one edge on the long side of the power generation unit 103 The short of the power generation unit One edge 104 on the side 104 One edge 110 on the short side of the power generation unit 110 Connection between the power generation units 120 Terminal plate 121 Base sheet 122 Metal layer for easy soldering

Claims (8)

A plurality of substantially spherical photoelectric conversion elements each having a spherical first semiconductor and a second semiconductor layer covering the surface of the first semiconductor, the second semiconductor layer having an opening exposing the first semiconductor;
A support mainly composed of aluminum or an aluminum alloy that supports the photoelectric conversion element and is electrically connected to the first semiconductor or the second semiconductor layer of the photoelectric conversion element;
A metal sheet mainly composed of aluminum or an aluminum alloy electrically connected to the second semiconductor layer or the first semiconductor of the photoelectric conversion element; and
An electrical insulating layer for insulating the support and the metal sheet;
A photoelectric conversion device comprising a power generation block consisting of a plurality of power generation units that are electrically connected to each other or a power generation unit comprising:
A terminal plate is connected to each of the support of the power generation unit located at one end of the power generation block and the metal sheet of the power generation unit located at the other end, and the terminal plate is a base sheet made of aluminum or an aluminum alloy And a metal layer mainly composed of at least one selected from the group consisting of copper, brass, tin, iron, silver, and solder, which is bonded to one side of the base sheet. A photoelectric conversion device, wherein a material sheet side is welded to each of the support and the metal sheet. A plurality of substantially spherical photoelectric conversion elements each having a spherical first semiconductor and a second semiconductor layer covering the surface of the first semiconductor, the second semiconductor layer having an opening exposing the first semiconductor;
A conductive support that supports the photoelectric conversion element and has a plurality of holes for arranging the photoelectric conversion elements one by one, wherein the second semiconductor layer of the photoelectric conversion element is at the edge of the hole A support mainly composed of aluminum or aluminum alloy that is electrically connected and has the exposed portion of the first semiconductor facing the back surface;
An electrically insulating layer bonded to the back side of the support and having a hole in at least a portion of the portion facing the exposed portion of the first semiconductor; and
A metal sheet mainly composed of aluminum or aluminum alloy joined to the electrical insulation layer and electrically connected to each other of the first semiconductors of the plurality of photoelectric conversion elements through holes in the electrical insulation layer;
A photoelectric conversion device comprising a power generation block consisting of a plurality of power generation units that are electrically connected to each other or a power generation unit comprising:
A terminal plate is connected to each of the support of the power generation unit located at one end of the power generation block and the metal sheet of the power generation unit located at the other end, and the terminal plate is a base sheet made of aluminum or an aluminum alloy And a metal layer mainly composed of at least one selected from the group consisting of copper, brass, tin, iron, silver, and solder, which is bonded to one side of the base sheet. A photoelectric conversion device, wherein a material sheet side is welded to each of the support and the metal sheet.   The photoelectric conversion device according to claim 1 or 2, wherein a base sheet side of the terminal plate is welded to each of the support and the metal sheet by ultrasonic welding.   The photoelectric conversion device according to claim 1, wherein the terminal plate is a clad plate of the base sheet and a copper sheet.   The photoelectric conversion device according to claim 1, wherein the terminal plate includes a clad plate of the base sheet and a copper sheet and a solder layer coupled to the copper sheet side.   The photoelectric conversion element includes an antireflection film that covers a surface of the second semiconductor layer, and the second semiconductor layer and the antireflection film each include an opening that exposes the first semiconductor at the same portion. Item 6. The photoelectric conversion device according to any one of Items 1 to 5.   The photoelectric conversion device according to claim 1, wherein the support has a recess having the hole at the bottom adjacent to the surface, and has a reflecting mirror layer on the inner surface of the recess. (A) a plurality of substantially spherical photoelectric conversion elements, each having a spherical first semiconductor and a second semiconductor layer covering the surface thereof, wherein the second semiconductor layer has an opening through which the first semiconductor is exposed; A support mainly composed of aluminum or an aluminum alloy that supports the conversion element and is electrically connected to the first semiconductor or the second semiconductor layer of the photoelectric conversion element, the second semiconductor layer or the first semiconductor of the photoelectric conversion element Preparing a plurality of power generation units comprising a metal sheet mainly composed of aluminum or an aluminum alloy electrically connected to the substrate, and an electrical insulating layer that insulates the support and the metal sheet;
(B) a step of electrically connecting a plurality of the power generation units in series or in parallel to each other by welding the ends of the power generation units and / or metal sheets;
And (c) a base sheet made of aluminum or an aluminum alloy on each of the support of the power generation unit located at one end of the plurality of connected power generation units and the metal sheet of the power generation unit located at the other end And a terminal board having a metal layer mainly composed of at least one selected from the group consisting of copper, brass, tin, iron, silver, and solder, which is bonded to one side of the base sheet. Welding the base sheet side of
A process for producing a photoelectric conversion device comprising:

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