JP2011159746A - Back circuit sheet for solar cell, solar cell module, and method of manufacturing the back circuit sheet for solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back circuit sheet for a solar cell that improves a mounting strength of a solar-battery cell, and prevents a circuit layer from being peeled off from an insulating base material in a solar cell module of a back-contact system. <P>SOLUTION: The back circuit sheet for the solar cell is formed of an insulating base material 11 made of a composite material containing fibers and a resin, and a circuit layer 12 laminated on the surface of the insulating base material 11 and electrically connected to a solar-battery cell. The circuit layer is embedded into the surface of the insulating base material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell back surface circuit sheet which is a member constituting a solar cell module, a solar cell module using the solar cell module, and a method for manufacturing a solar cell back circuit sheet. In particular, the present invention relates to a solar cell back circuit sheet that is superior in weather resistance, heat resistance, moisture resistance, and mechanical properties as compared with conventional methods.

  In recent years, solar cells have attracted attention as a new energy source that is pollution-free and friendly to the global environment. The structure of a general solar cell module is to cover the surface irradiated with sunlight with glass, seal the solar cells with a sealing layer made of thermoplastics, and heat and weather resistant plastic materials on the back side The structure is made by sticking together. One solar cell module is mounted with several to several tens of solar cells connected in series or in parallel.

  Since the solar cell module is used outdoors, its structure requires sufficient durability and weather resistance. In particular, the circuit used for the back surface of the solar battery cell is required to have water vapor barrier properties as well as weather resistance. This is because the module output may be reduced if the filler is denatured (peeled or discolored) or the wiring is corroded by the permeation of moisture.

  Conventionally, as a back surface circuit sheet for a solar cell used in this solar cell module, a laminate structure in which an adhesive is applied to both sides of a polyester sheet base material and a polyvinyl fluoride film is bonded is used. . However, since the adhesive used in this configuration is mainly composed of a urethane-based resin or a polyester-based resin, for example, when used for a long period of more than 10 years, there is a possibility that peeling due to alteration of the adhesive may occur. It was pointed out that there was.

  For example, urethane-based resin adhesives and polyester-based resin adhesives are susceptible to hydrolysis due to moisture absorption, and the heat resistance of the resin itself is low, so that it deteriorates under the influence of heat, humidity, and even ultraviolet rays when used for a long period of time. As a result, peeling at the adhesive interface is likely to occur due to a decrease in mechanical strength.

  In order to prevent this problem, a method of directly extruding and laminating a fluororesin on a PET base material has been proposed in order to prevent peeling due to deterioration of the adhesive. However, since the polyester-based sheet base material shrinks at the melting temperature of the fluororesin, there are problems such as generation of wrinkles in the laminated sheets. In addition, it is conceivable to use a heat-resistant polyethylene terephthalate (PET) sheet or polyethylene naphthalate (PEN) sheet with improved heat shrinkage, but this is not preferable because of the problem of increased costs.

  Recently, a solar battery module called a back contact system has been developed in which wiring between solar battery cells, which causes a loss of light receiving area, is formed on the back circuit. In this system, the solar cells are connected by a solar battery back circuit sheet (hereinafter referred to as a back contact circuit material) having a circuit formed on the surface. That is, a terminal part is formed in the back surface of a photovoltaic cell, and photovoltaic cells are electrically connected through the circuit layer formed on the surface of the back surface circuit sheet for solar cells. In this solar cell back surface circuit sheet, the circuit other than the terminal portion is covered with an insulating layer, and the corrosion resistance of the circuit and the insulation between the circuits are ensured.

  The currently proposed back circuit sheet for solar cells for back contacts is made by applying an adhesive on both sides of a polyester-based sheet base material, laminating metal foil on one side, and weathering such as fluororesin on the other side. The structure which laminated the functional resin film is comprised. However, even in this configuration, since an adhesive mainly composed of urethane or polyester is used, there is a problem of peeling during long-term use. Further, there is a problem that insulation between circuits cannot be secured due to insufficient insulation of the adhesive.

  Furthermore, the polyester-based film substrate has a low heat resistance and a problem that process conditions are limited. In other words, the drying temperature when forming the adhesive layer, the laminating temperature when laminating copper foil and weather-resistant resin film, the curing temperature when forming the insulating layer, etc. It becomes difficult to process. Thereby, there is a problem that not only the materials that can be used are limited, but also the productivity is lowered.

  On the other hand, the polyester-based film base material has a large dimensional change at high temperatures, and in the solar battery back surface circuit sheet, stress tends to concentrate on the joint portion with the solar battery cell. As a result, there is a problem that the connection reliability cannot be ensured, for example, the terminal joint part peels off or a crack occurs. Furthermore, there is also a problem that warpage is likely to occur in the circuit after lamination due to a difference in thermal expansion between the copper foil and the polyester film substrate.

  In addition, when the back contact solar cell back circuit sheet for the back contact is made by hand-industry work like the current solar cell module production by soldering iron etc., it is said that the capacity is still insufficient when considering the rapid demand in the future. Is the current situation. Therefore, there is a need for a mechanism that allows efficient work with a view to connecting circuits and automating the lamination process. In addition, the back contact circuit currently proposed is based on the dimensional accuracy of each stack and the melting metal or conductive resin (hereinafter referred to as a conductive adhesive) such as solder between the solar cell back electrode and the circuit. Strong adhesiveness is required.

JP 2001-68701 A JP 2001-68695 A Japanese Patent Laid-Open No. 61-251176

  By the way, when connecting a solar cell and a circuit layer by heat melting of a meltable metal such as solder or a conductive resin, the insulating base material and the solar cell are strengthened with a conductive adhesive from the viewpoint of mechanical strength. It is preferable that they can be integrated. However, since the conductive adhesive is more familiar with the circuit layer than the insulating base material, it is difficult to concentrate on and contact the circuit layer and adhere to the insulating base material. Therefore, since it is not possible to sufficiently ensure the wet-up of the conductive adhesive from the insulating base material to the solar battery cell, the insulating base material and the solar battery cell cannot be integrated to a desired strength, There has been a problem that the mounting of the solar cell on the insulating base material becomes fragile.

  In addition, an EVA sheet is often used as the sealing layer for sealing the solar battery cells. Since acetic acid gas is released from the EVA sheet over time, the circuit layer is corroded by the acetic acid gas. As a result, there was a concern of peeling from the insulating substrate.

  The present invention has been made in view of such problems, and in a back contact solar cell module, the mounting strength of the solar cells can be improved, and the circuit layer can be prevented from peeling off from the insulating substrate. It is an object of the present invention to provide a solar cell back surface circuit sheet, a solar cell shell using the solar cell back circuit sheet, and a method for producing the solar cell back circuit sheet.

In order to solve the above problems, the present invention proposes the following means.
That is, the solar cell back surface circuit sheet according to the present invention is an insulating base material made of a composite material containing fibers and resin, and a circuit that is laminated on the surface of the insulating base material and electrically connected to the solar cells. And the circuit layer is embedded in the surface of the insulating base material.

According to the solar cell back surface circuit sheet having such a feature, since the circuit layer is embedded in the surface of the insulating base material, the circuit layer is exposed to the outside by the amount corresponding to the side surface in the thickness direction of the circuit layer according to the embedded amount. The surface area of the circuit layer is reduced. Therefore, since the contact area with the conductive adhesive 14 is also reduced, the amount of the conductive adhesive 14 that comes into contact with the circuit layer can be reduced. Thereby, the amount of the conductive adhesive 14 adhering to the insulating base material can be increased, and sufficient wetting of the conductive adhesive 14 from the insulating base material to the solar battery cell can be ensured.
In addition, since the circuit layer is buried in the insulating base material, not only the back surface in the thickness direction of the circuit layer but also the side surface is covered with the insulating base material, thereby reducing the contact area with the acetic acid gas released from the EVA sheet. Can be made.

In the said back surface circuit sheet for solar cells, it is preferable that the amount of embedding with respect to the surface of the said insulation base material of the said circuit layer is set to 10% or more of the thickness of the said circuit layer.
At least 10% or more of the thickness of the circuit layer is buried in the insulating base material, so that wetting of the conductive adhesive can be sufficiently ensured and the mounting strength of the solar battery cell can be improved. By effectively reducing the contact area, the circuit layer can be prevented from peeling off.

  The solar cell module according to the present invention includes a translucent substrate disposed on the light receiving surface side, a back sheet disposed on the back side of the translucent substrate, and between the translucent substrate and the back sheet. A solar cell module comprising: a solar cell disposed and electrically connected to the circuit layer; and a sealing layer that seals the solar cell, wherein the backsheet is the back surface for the solar cell. It is a circuit sheet.

  According to the solar cell module having such a characteristic, since the back circuit sheet for the solar cell is adopted, it is possible to improve the mounting strength of the solar cell and to prevent the circuit layer from peeling from the insulating base material. can do.

  According to the method for manufacturing a back circuit sheet for a solar cell according to the present invention, a metal foil and an insulating base material made of a composite material containing a fiber and a resin are laminated in a half-pressurized state by applying pressure heat treatment. A step of patterning the metal foil laminated on the insulating base material layer to form a circuit layer, and further subjecting the insulating base material layer and the circuit layer to pressure heating treatment, A step of melting the resin in the insulating substrate and burying the circuit layer in the melted resin. In addition, it is preferable that the process of laminating | stacking the said metal foil on the said insulating base material is performed using a lamination press machine.

  According to the method for manufacturing a back circuit sheet for a solar cell having such characteristics, when the metal foil and the insulating base material are subjected to pressure heating treatment, the insulating base material is usually compressed to the fiber thickness. It is set as the state which left the compression margin of resin by keeping in a compression state. Then, the circuit layer can be buried in the resin of the insulating base material by compressing the entire circuit layer by pressure heating treatment again after the circuit is formed.

Moreover, in the manufacturing method of the back surface circuit sheet for solar cells in this invention, the process of laminating | stacking the said metal foil on the said insulating base material may be performed using a laminating machine.
In this case, it is possible to easily realize the state where the resin compression margin is left as described above, and to achieve cooperation between processes with the photosensitive resist film laminating process which is a subsequent process. Efficiency can be improved.

  According to the back circuit sheet for solar cell and the solar cell module of the present invention, the circuit layer can be laminated in a state where it is buried in the bordered substrate, thereby improving the mounting strength of the solar cell. It becomes possible to prevent the circuit layer from peeling off from the insulating base material.

It is a longitudinal cross-sectional view which shows schematic structure of the back surface circuit sheet for solar cells. It is a figure explaining the 1st step of the manufacturing method of the back surface circuit sheet for solar cells shown in FIG. It is a figure explaining the other aspect of the process in which metal foil is laminated and fixed to the insulating base material shown to Fig.2 (a). It is a figure explaining the 2nd step of the manufacturing method of the back surface circuit sheet for solar cells shown in FIG. It is a longitudinal cross-sectional view which shows schematic structure of a solar cell module. It is a figure explaining the process in which a photovoltaic cell is mounted in the back surface circuit sheet for solar cells.

The embodiment of the back circuit sheet for solar cells of the present invention will be described.
In FIG. 1, the back surface circuit sheet for solar cells of this embodiment is shown. This back surface circuit sheet 10 for solar cells includes an insulating base material 11 and a circuit layer 12 provided on the front surface side of the insulating base material 11, and is used for connecting so-called back contact type solar cells 30. .

  As the insulating base material 11, a plate-shaped member made of a composite material containing fibers and a resin, for example, a prepreg obtained by impregnating or applying a thermosetting resin to a fiber base material and drying it is used. Glass fiber, aramid fiber, fluorine fiber, polyester fiber, polyarylate fiber, etc. are used as the fiber base material, but glass fiber should be adopted from the viewpoint of affinity with thermosetting resin, insulation reliability, and material cost. Is preferred.

  In addition to plain weave, twill weave, and satin weave, these fibers are preferably woven fabrics using long fibers such as a plain plain weave and a stitched calami weave. In addition, when a short fibrous material is used, the fiber end tends to protrude from the surface of the insulating substrate 11, and pinholes or bubbles are easily generated in the protective layer.

  Further, as the thermosetting resin impregnated in these fiber base materials, an addition polymerization type thermosetting resin that cures without generating by-products is preferable, and epoxy resin, unsaturated polyester resin, phenol resin, diallyl Phthalate resin, acrylic resin, cyanate resin, cyanate ester resin-epoxy resin, cyanate ester-maleimide resin, cyanate ester-maleimide-epoxy resin, maleimide resin, maleimide-vinyl resin, bisallyl nadiimide resin, other thermosetting It is preferable to use a functional resin and a composition obtained by appropriately blending two or more of these. The thickness of the insulating substrate 11 is preferably set to 50 μm or more, particularly in the range of 100 μm to 300 μm, in order to ensure dielectric breakdown resistance and puncture resistance.

  The circuit layer 12 is a layer that is electrically connected to an electrode 31 of the solar battery cell 30 described later, and is laminated on the surface side of the insulating base material 11. The circuit layer 12 has a pattern in which a large number of solar cells 30 stacked on the solar cell back surface circuit sheet 10 are electrically connected in series. For this reason, it does not cover the entire range of the surface of the insulating base material 11, but has a gap that exposes the surface of the insulating base material 11 to the light receiving surface side according to the shape of the pattern.

  As a material constituting the circuit layer 12, a material having low electric resistance, for example, copper, aluminum, iron-nickel alloy or the like is used. Moreover, a conductive polymer can also be used.

  In particular, the circuit layer 12 in the present embodiment is buried in the surface of the insulating base material 11 so as to be substantially flush with the surface of the insulating base material 11. Note that the circuit layer 12 does not necessarily have to be buried in the insulating base material 11 in the thickness direction, and at least 10% or more of the thickness of the circuit layer 12 may be buried in the surface of the insulating base material 11.

Next, the manufacturing method of the said back surface circuit sheet 10 for solar cells is demonstrated.
In the manufacturing method of the solar cell back surface circuit sheet 10 of the present embodiment, first, as shown in FIG. 2A, a metal foil 18 made of a metal such as copper, aluminum, iron-nickel alloy or the like is disposed in the upper layer. At the same time, the insulating base material 11 is disposed and laminated in the lower layer, and sandwiched between the plates 101 and 101 of the laminating press connected to the heat source from above and below.

  In addition, although the lamination | stacking conditions of the insulating base material 11 and the metal foil 18 differ also with the kind of fiber base material and thermosetting resin which comprise the insulating base material 11, generally temperature is 150-200 degree | times and pressure Is 0.5 to 3.0 MPa, and the time is 10 to 40 minutes. The lamination temperature is preferably carried out at the melting temperature of the impregnating resin ± 30 ° C. When the lamination temperature is too low, the resin does not melt sufficiently, and the adhesive strength between the insulating base material 11 and the metal foil 18 tends to be low due to insufficient wetting and spreading to the base material surface. On the other hand, if the lamination temperature is too high, bubbles are likely to be generated due to the rapid evaporation of the solvent in the impregnating resin. In addition, the viscosity of the resin is too low and the resin flows out to the periphery of the substrate, causing a problem that the thickness of the circuit becomes non-uniform.

  Here, as a lamination condition of the insulating base material 11 and the metal foil 18, 150 ° C., a pressure of 0.5 Mpa, a lamination time of 10 minutes, which is the lower limit value of the above range, is adopted, and pressure heat treatment is performed under these conditions. Apply. As a result, the thermosetting resin on the surface of the insulating base material 11 is melted and re-cured, whereby the metal foil 18 is bonded, and the insulating base material 11 and the metal foil 18 are laminated and fixed.

  The lamination condition of the insulating base material 11 and the metal foil 18 is a setting as a minimum value necessary for pressurizing and heating the insulating base material 11 and the circuit layer 12, and particularly the pressure is compared. It is in a semi-pressurized state with a small pressure. As described above, in this embodiment, the insulating base material 11 and the metal foil 18 are kept in a semi-compressed condition so that the insulating base material 11 and the insulating base material 11 remain in a state of leaving a compression margin of the thermosetting resin. A metal foil 18 is laminated. In other words, the insulating base material 11 and the metal foil 18 are laminated and fixed with the melting ability of the thermosetting resin in the insulating base material 11 on the lower side of the metal foil 18 being in the bottom bottom state.

  In addition, as described above, the method is not limited to the method using the plates 101 and 101 of the laminating press machine. For example, as shown in FIG. 3, the laminating machine 105 is used to laminate and fix the insulating base material 11 and the metal foil 18. Also good. That is, a rubber roll heated at a high temperature is disposed only on the upper side, and a metal foil 18 of copper, aluminum or the like having a film thickness of about 12 μm to 35 μm is disposed in the upper layer and the insulating base material 11 is disposed in the lower layer. And the insulating base material 11 are laminated. And by sending this laminated body between the rubber rolls set to a predetermined feed rate, upper and lower pressure, and predetermined temperature, the thermosetting resin of the insulating base material 11 is melted and re-cured, and the insulating base material 11 and The metal foil 18 is laminated and fixed.

  Even when this laminating machine is used, by keeping the lamination condition of the insulating base material 11 and the metal foil 18 in a semi-compressed state, these insulating base materials 11 are left in a state where a margin for compression of the thermosetting resin remains. And the metal foil 18 are laminated and fixed. Moreover, since cooperation between processes with the lamination process of the photosensitive resist film 107 which is a post process can be aimed at, manufacturing efficiency can be improved.

  Thus, when the insulating base material 11 and the metal foil 18 are laminated and fixed by the above method, for example, compared to the case where the lamination condition is set to the upper limit value with a lamination press machine and the lamination is fixed, the pressure bonding temperature, the pressure, and the pressure bonding time. Is insufficient, the adhesion between the metal foil 18 and the insulating base material 11 is insufficient.

  Next, as shown in FIG. 2 (b), the photosensitive resist film 107 is laminated under a predetermined condition by using a laminating machine 105 on the surface of the metal foil 18 laminated and bonded. Thereafter, in order to form an arbitrary circuit pattern on the photosensitive resist film 107, the photosensitive resist film 107 is directly irradiated with a laser as shown in FIG. A mask film using the film is vacuum-contacted and subjected to UV irradiation.

  Then, when the photosensitive resist film 107 is subjected to a melting treatment with an alkaline developer, among the exposed portion 109 and the non-exposed portion 110 generated by the transmission and non-transmission of light in the process shown in FIG. Only the non-exposed portion 110 is melted, and the metal foil 18 disposed under the photosensitive resist film 107 is exposed (see FIG. 2D).

  Subsequently, the portion exposed on the surface of the metal foil 18 is subjected to etching until a surface of the insulating substrate 11 is exposed by performing a spray etching method using a ferric chloride aqueous solution or a cupric chloride aqueous solution (FIG. 2 (e)). Note that the portion of the metal foil 18 that is not etched is formed as the circuit layer 12, but the adjustment of the width and interval of the circuit pattern is caused by changes in the conditions of the spray etching method. It is necessary to grasp and adjust the concentration of the ferric chloride aqueous solution or the cupric chloride aqueous solution and the flow rate of the base material during corrosion.

  Then, the exposed portion 109 of the photosensitive resist film 107 left on the metal foil 18 that has not been etched is stripped with an alkaline stripping solution to neutralize and remove the oxide film on the surface of the metal foil 18 to dilute sulfuric acid. Rinse with the main component, wash with water and dry. Thereby, as shown in FIG.2 (f), the laminated structure by which the circuit layer 12 is arrange | positioned on the insulating base material 11 can be obtained.

  Next, a process of burying the circuit layer 12 in the insulating base material 11 is performed. That is, as shown in FIG. 4, the laminated structure of the insulating base material 11 and the circuit layer 12 is sandwiched again under predetermined conditions using the laminated press machine plates 101 and 101. And in the state heated at about 200 degreeC, it presses by a comparatively high pressure from the upper and lower sides, ie, a pressure higher than the pressure at the time of laminating and fixing the metal foil 18 on the insulating base material 11. As a result, the thermosetting resin of the insulating substrate 11 is melted, and the circuit layer 12 is buried in the melted thermosetting resin. At this time, the amount of burying of the circuit layer 12 with respect to the insulating base material 11 is adjusted by adjusting the magnitude of the pressure applied by the plates 101 and 101 of the laminating press and the application time of the pressure. Thereby, the back surface circuit sheet 10 for solar cells of this embodiment in which the circuit layer 12 was embedded in the insulating base material 11 by the predetermined amount of the thickness can be obtained.

The solar cell back circuit sheet 10 is used in a solar cell module. FIG. 5 shows a solar cell module using the solar cell back surface circuit sheet 10.
This solar cell module 1 seals the back surface circuit sheet 10 for solar cells disposed on the back surface side, the solar cells 30 disposed on the back circuit sheet 10 for solar cells, and the back surface side of the solar cells 30. And a sealing layer 40.
Furthermore, in the back surface circuit sheet 10 for solar cells used for this solar cell module 1, the barrier layer 13 is arrange | positioned in the back surface side, and also in order to fix the photovoltaic cell 30 to the back circuit sheet 10 for solar cells. A conductive adhesive 14 is used.

  The barrier layer 13 is a layer that adjusts air permeation. For the barrier layer 13, a material having long-term reliability such as weather resistance and insulation is used. For example, a fluororesin film, a low oligomer / heat-resistant polyethylene terephthalate (PET) film / polyethylene naphthalate (PEN) film, silica (SiO 2 ) Evaporated film, aluminum foil, etc. are used.

  The conductive adhesive 14 is a member that assists electrical connection between the circuit layer 12 and the solar battery cell 30. As the material of the conductive adhesive 14, a material having a low electric resistance is used. Especially, since the electrical resistance with the circuit layer 12 becomes low, it is preferable to contain 1 or more types of metals chosen from the group which consists of silver, copper, tin, lead, nickel, and gold.

  Since the conductive adhesive 14 has a high viscosity and can be easily formed into a desired shape, it is one or more metals selected from the group consisting of silver, copper, tin, and solder (copper and lead are the main components). It is preferable that it is formed with the electrically conductive paste containing this.

  The conductive paste is preferably a low temperature curing type. If the conductive paste is a low-temperature curing type, the solar cell electrode and the circuit layer 12 can be electrically connected at a low temperature of 120 to 160 ° C. Since 120 to 160 ° C. is a temperature at which softening, melting, and crosslinking of the EVA sheet that can be used as the sealing layer 40 occurs, when the EVA sheet is used as the sealing layer 40, the solar cell can be easily processed. The electrode of the cell 30 and the conductive adhesive 14 formed from the conductive paste can be more easily electrically connected.

  Low-temperature curing type conductive paste contains a polymer and a conductive filler, and develops conductivity by physical contact of the conductive filler by curing the polymer. Coordinates and reduces silver or copper to organic matter The thing which contains a nanoparticle and expresses electroconductivity by carrying out low temperature sintering (120-160 degreeC) is mentioned. The latter material is preferable in that the electric resistance becomes lower.

  Examples of the translucent substrate 20 include a glass substrate and a transparent resin substrate. Examples of the transparent resin constituting the transparent resin substrate include acrylic resin, polycarbonate, and polyethylene terephthalate.

  Examples of the solar battery cell 30 include a single crystal silicon type, a polycrystalline silicon type, an amorphous silicon type, a compound type, and a dye sensitized type. Among these, the single crystal silicon type is preferable in terms of excellent power generation efficiency. The solar battery cell 30 includes positive and negative electrodes 31, 31 on the back side.

  The sealing layer 40 is formed of a sealing film. As the sealing film, for example, an EVA sheet, an ethylene / (meth) acrylic acid ester copolymer film, a fluororesin film such as polyvinylidene fluoride, etc. are generally used. In this embodiment, the EVA sheet is used. Is adopted. Usually, two or more sealing films are used so as to sandwich the solar battery cell 30 therebetween.

  Here, for example, as shown in FIG. 6, the solar battery cell 30 is mounted on the solar battery back surface circuit sheet 10 by disposing the conductive adhesive 14 on the circuit layer 12 of the solar battery back circuit sheet 10. The solar battery cell 30 is disposed so that the conductive adhesive 14 faces the electrode 31 of the solar battery cell 30, and further includes the back battery circuit sheet 10 for the solar battery, the conductive adhesive 14, and the solar battery cell 30. This is done by heating and pressing the laminate.

  In addition, as a formation method of the electroconductive adhesive 14, methods, such as plating, screen printing, dispensing, transfer, are applicable, for example. In that case, it is preferable to use a conductive paste containing one or more metals selected from the group consisting of silver, copper, tin, and solder because the desired shape can be easily obtained. Furthermore, a low temperature curing type conductive paste is more preferable in that the electrode 31 of the solar battery cell 30 and the conductive adhesive 14 can be more easily electrically connected.

  And then, the solar battery cell 30 is sealed with the sealing layer 40 so as to cover the solar battery cell 30 from the surroundings on the surface side of the solar battery back circuit sheet 10, and then the surface of the sealing layer 40 The solar cell module 1 of this embodiment can be obtained by arrange | positioning the translucent base material 20 in the side and forming the barrier layer 13 in the back surface of the back surface circuit sheet 10 for solar cells.

  According to the solar cell back surface circuit sheet 10 and the solar cell module 1 configured as described above, the solar battery cell 30 is laminated on the circuit layer 12 provided on the surface of the insulating base material 11 by removing the conductive adhesive 14. Thus, the solar cells 30 can be electrically connected in series. Thus, since the lamination | stacking to the back surface circuit sheet 10 for solar cells and the connection of the photovoltaic cells 30 can be performed simultaneously, the solar cell module 1 can be manufactured easily and productivity is improved. Can be high.

  Furthermore, since the insulating substrate 11 is made of a composite material, the solar cell back surface circuit sheet 10 is excellent in dimensional stability and rigidity. In particular, it is excellent in dimensional stability and rigidity, for example, compared with a back circuit sheet for a solar cell made of a PET base material or a PEN base material that has been widely used conventionally. Therefore, the back surface circuit sheet 10 for solar cells has the outstanding physical property because the insulating base material 11 consists of composite materials.

  In particular, according to the solar cell back surface circuit sheet 10 of the present embodiment, since the circuit layer 12 is buried in the surface of the insulating base material 11, only the side surface in the thickness direction of the circuit layer 12 according to the amount of burying. The surface area of the circuit layer 12 exposed to the outside is reduced. Therefore, since the contact area with the conductive adhesive 14 used when connecting with the solar battery cell 30 is also reduced, the amount of the conductive adhesive 14 that comes into contact with the circuit layer 12 can be reduced.

  Thereby, the amount of the conductive adhesive 14 adhering to the insulating base material 11 can be increased, and sufficient wetting of the conductive adhesive 14 from the insulating base material 11 to the solar battery cell 30 can be ensured. Thereby, the mounting strength of the photovoltaic cell 30 can be improved.

  In addition, since the circuit layer 12 is buried in the insulating base material 11, not only the back surface in the thickness direction of the circuit layer 12 but also the side surface is covered with the insulating base material. The contact area with the EVA sheet used for sealing the solar battery cells 30 when configuring the solar battery module can be reduced.

  That is, acetic acid gas that corrodes the circuit layer 12 is released from the EVA sheet with the passage of time. However, in the back surface circuit sheet for a solar cell 10 of the present embodiment, the contact area of the circuit layer with the EVA sheet is minimized. Since it can suppress, corrosion of the circuit layer 12 can be prevented and peeling from the insulating base material 11 of the circuit layer 12 can be avoided.

  Furthermore, since at least 10% of the thickness of the circuit layer 12 is buried in the insulating base material 11, the effects of improving the mounting strength of the solar battery cell 30 and avoiding the peeling of the circuit layer 12 are ensured. Since the contact area with respect to the insulating base material 11 of the circuit layer 12 is increasing, the adhesiveness with respect to the insulating base material 11 of the circuit layer 12 itself can also be improved. Therefore, for example, even when thermal expansion occurs in each member during high heat, it is possible to prevent the circuit layer 12 from peeling from the insulating base material 11.

  Moreover, according to the manufacturing method of the solar cell back surface circuit sheet 10 of the present embodiment, when the metal foil 18 and the insulating base material 11 are subjected to pressure heating treatment, the insulating base material 11 is usually made of a fiber base material. By compressing to the thickness, it is in a state in which the compression margin of the thermosetting resin is left by keeping it in a semi-compressed state, and then the circuit layer 12 is compressed again by pressure heating treatment after the circuit layer 12 is formed. The layer 12 can be easily embedded in the resin of the insulating base material 11. Thereby, the solar cell back surface circuit sheet 10 of this embodiment can be obtained easily.

As mentioned above, although embodiment of this invention was described in detail, unless it deviates from the technical idea of this embodiment, it is not limited to these, A some design change etc. are possible.
For example, the solar cell back surface circuit sheet 10 of the embodiment is composed only of the insulating base material 11 and the circuit layer 12, but after having the barrier layer 13 and the conductive adhesive 14 from the beginning, these insulating groups The solar cell back surface circuit sheet 10 may be composed of the material 11, the circuit layer 12, the barrier layer 13, and the conductive adhesive 14.

  Moreover, in the back surface circuit sheet 10 for solar cells, the overcoat layer which coat | covers except the part which contacts the electrode 31 of the photovoltaic cell 30 in the circuit layer 12 may be provided. Examples of the insulating material constituting the overcoat layer include an epoxy resin, an acrylic resin, and a urethane resin. These resins may be used alone or in combination of two or more. By providing this overcoat layer, short circuit between adjacent circuit layers 12 can be prevented, and corrosion of the circuit layer 12 by acetic acid gas released from the EVA sheet can be more effectively prevented.

<Example 1>
Copper foil (Nikko metallic JTCS foil, thickness 35 μm) on one side of prepreg (insulating base material) (Mitsubishi Gas Chemical Co., Ltd .; CCL-EL190, thickness 200 μm), and 1 mm thick Teflon (registered trademark) plate The stainless steel plate and the cushion material were appropriately arranged on the outside, and set between the hot plates of the test press machine. Vacuuming was started in this state, and pressurization was started when the degree of vacuum reached 1.5 kPa. The lamination conditions were 180 ° C. for 30 minutes and the pressure was 2.0 MPa. The apparatus used was a test press (made by Kitagawa Seiki Co., Ltd., 500 mm × 500 mm type), and the resulting laminated sheet had a good finish with no warpage or bubbles.

<Example 2>
A copper foil (Nikko metallic JTCS foil, thickness 35 μm) is placed on the upper surface of one side of a prepreg (insulating material) (Mitsubishi Gas Chemical Co., Ltd .; CCL-EL190 thickness 200 μm), and a rubber roll heated at around 250 ° C. is arranged only on the upper side. Using a laminating machine (manufactured by Taisei Laminator, VA2-700PH), lamination was performed at a roll pressure of 1 Mps and a through speed of 0.01 m to 0.05 m / min.

The following steps were added to the laminated sheet composed of the prepreg and copper foil prepared in Example 1 and Example 2 to create a back circuit sheet for solar cells.
First, a photosensitive resist film was laminated on the surface of the laminated sheet copper foil with a laminating machine (VAII-700PH, manufactured by Taisei Laminator), and laminated at a temperature of 110 ° C., a pressure of 1 Mpa, and a through speed of 2 m to 3 m / min.

  Then, the film mask which described the circuit pattern which should be formed with the specification which UV light permeate | transmits was made to vacuum-adhere to the base material which accumulated the photosensitive resist film, and UV exposure irradiation was performed. After about 2 to 3 minutes, the exposure was stopped, and the exposed portion was eluted with an alkali development layer to expose the surface of the copper foil.

  Etching the exposed copper foil surface with a ferric chloride solution until the prepreg surface is exposed, dissolving the resist film with an aqueous sodium hydroxide solution, pickling with dilute sulfuric acid, washing with water, and drying. A circuit layer made of copper foil was formed on the prepreg.

  Next, in order to bury the circuit layer formed on the prepreg so as to be flush with the surface of the prepreg, it is sandwiched between Teflon (registered trademark) plates with a thickness of 1 mm, Set. Vacuuming was started in this state, and pressurization was started when the degree of vacuum reached 1.5 kPa. The lamination conditions were 200 ° C. for 30 minutes and the pressure was 3.0 MPa. The apparatus used was a test press machine (Kitakawa Seiki, 500 mm × 500 mm type).

By the above process, the resin impregnated in the prepreg remaining immediately below the circuit layer oozed out from the side of the circuit layer, and as a result, the circuit layer was buried in the resin.
In the above process, on the surface of the laminated sheet, solder resist ink (manufactured by Taiyo Ink Manufacturing Co., Ltd., PSR-4000 EG30) as an insulating layer is printed on a circuit on the basis of the position control mark previously printed by the printing machine. The resin was coated so that the resin thickness was 35 μm. Next, preliminary drying was performed at 80 ° C. for 30 minutes, and single-sided exposure was performed at 500 mJ using a film mask. Further, spray development was performed with a 1.0% sodium carbonate solution for 120 seconds to form an opening in the insulating layer, and then heat-cured at 150 ° C. for 30 minutes. The solar cell back surface circuit sheet thus obtained is assumed to be used as a back contact circuit material.

Evaluation of the back surface circuit sheets for solar cells of Example 1 and Example 2 was performed.
<Adhesive strength measurement 1>
An adhesive strength measurement test was conducted. The test conditions are as follows.
Pretreatment conditions; None; Tensilon RTC-1250 Distance between chucks manufactured by Orientec; 60 mm
Sample: 10 mm × 100 mm × about 0.4 mm n = 5
Crosshead speed: 5.0mm / min
<Adhesive strength measurement 2>
An adhesive strength measurement test was conducted. The test conditions are as follows.
Pretreatment conditions: 85 ° C / 85% / 3000h
The measurement method is the same as the adhesive strength measurement 1 <Adhesion strength measurement 3>
An adhesive strength measurement test was conducted. The test conditions are as follows.
That is, after the operation of cooling and heating to −40 ° C. to 80 ° C. at regular intervals was repeated 200 times, the adhesive strength was tested.
<Insulation reliability test>
A comb-type circuit is formed on a circuit sheet with a conductor wire of 550 μm and between conductors of 600, 400, and 100 μm, and a solder resist is coated on the circuit sheet. The insulation resistance value was monitored by applying a constant voltage between the conductors, and the presence or absence of a short circuit was confirmed.
<Circuit initial resistance (Ω) measurement test 1>
Prior to performing the adhesion strength measurement 2, the resistance value between the conductors of the comb circuit was measured with a tester, and an initial resistance measurement test of the circuit was performed.
<Initial resistance value (Ω) measurement test 2 of circuit>
After performing the adhesive strength measurement 2, the resistance value between the conductors of the comb circuit was measured with a tester, and an initial resistance value measurement test of the circuit was performed.
<Section observation by SEM>
The cross section of the comb circuit was observed with an electron microscope, and it was confirmed whether or not a short-circuit phenomenon due to metal ion melting occurred between the conductors.

<Evaluation results>
The evaluation results are shown in Table 1.

  As shown in Table 1, since the back surface circuit sheet for solar cell of the example does not use an adhesive that is susceptible to hydrolysis, it was found that there was little decrease in adhesive strength after 85 ° C./85%/3000 h treatment. Furthermore, it was found that the insulation reliability is excellent because lamination is performed in a vacuum without bubbles without using an adhesive. That is, it was proved that the durability was excellent as compared with the conventional case. It was also confirmed that the circuit layer was buried in the prepreg.

DESCRIPTION OF SYMBOLS 1 Solar cell module 10 Back surface circuit sheet 11 for solar cells Insulation base material 12 Circuit layer 13 Barrier layer 14 Conductive adhesive 18 Metal foil 30 Solar cell 31 Electrode 40 Sealing layer 101 Plate 105 Laminating machine 107 Photosensitive resist film 109 Exposed part 110 Non-exposed part

Claims (6)

An insulating substrate made of a composite material containing fibers and resin;
A circuit layer laminated on the surface of the insulating base material and electrically connected to the solar battery cell;
The back surface circuit sheet for solar cells, wherein the circuit layer is buried in the surface of the insulating substrate.   The back surface circuit sheet for a solar cell according to claim 1, wherein an amount of the circuit layer embedded in the surface of the insulating base is set to 10% or more of the thickness of the circuit layer. A translucent substrate disposed on the light receiving surface side, a back sheet disposed on the back side of the translucent substrate, and disposed between the translucent substrate and the back sheet, and electrically connected to the circuit layer A solar cell module comprising: a solar cell connected to a sealing layer; and a sealing layer for sealing the solar cell,
The back sheet is a back circuit sheet for a solar cell according to claim 1 or 2, wherein the back sheet is a solar cell module. Laminating a metal foil and an insulating base material made of a composite material containing fibers and a resin in a semi-pressurized state by applying pressure heat treatment;
Forming a circuit layer by patterning the metal foil laminated on the insulating base layer; and
And further subjecting the insulating base layer and the circuit layer to a pressure heating treatment to melt the resin in the insulating base and bury the circuit layer in the melted resin. The manufacturing method of the back surface circuit sheet for solar cells.   The method for producing a back circuit sheet for a solar cell according to claim 4, wherein the step of laminating the metal foil on the insulating substrate is performed using a laminating press.   The method for producing a back circuit sheet for a solar cell according to claim 4, wherein the step of laminating the metal foil on the insulating base is performed using a laminating machine.

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