WO2014020672A1 - Method for producing solar cell and solar cell - Google Patents

Method for producing solar cell and solar cell Download PDF

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Publication number
WO2014020672A1
WO2014020672A1 PCT/JP2012/069387 JP2012069387W WO2014020672A1 WO 2014020672 A1 WO2014020672 A1 WO 2014020672A1 JP 2012069387 W JP2012069387 W JP 2012069387W WO 2014020672 A1 WO2014020672 A1 WO 2014020672A1
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WO
WIPO (PCT)
Prior art keywords
solar cell
photoelectric conversion
conductive particles
connection electrode
conversion unit
Prior art date
Application number
PCT/JP2012/069387
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French (fr)
Japanese (ja)
Inventor
翔士 佐藤
悟司 東方田
Original Assignee
三洋電機株式会社
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Application filed by 三洋電機株式会社 filed Critical 三洋電機株式会社
Priority to PCT/JP2012/069387 priority Critical patent/WO2014020672A1/en
Priority to JP2014527845A priority patent/JP5934984B2/en
Publication of WO2014020672A1 publication Critical patent/WO2014020672A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a solar cell manufacturing method and a solar cell formed by the method.
  • thermosetting conductive paste As one of the conductor formation methods for solar cells, a method using a thermosetting conductive paste is known.
  • the thermosetting conductive paste is applied to the substrate by means of screen printing or the like, and is heat-treated at a temperature of about 100 ° C. to 300 ° C., thereby curing the resin and forming a conductive electrode.
  • thermosetting conductive paste containing conductive particles and a resin two or more kinds of conductive particles may be mixed and used, and the shape of the conductive particles may be spherical, flaky, or dendritic.
  • limiting such as a shape and a fibrous form, it is said that powder particles are easy to contact each other and it is advantageous at an electroconductive point.
  • a balance between the improvement of conductivity in the wiring electrode and the stress caused by the fusion is achieved.
  • a paste material containing conductive particles is prepared, the paste material is applied so as to have a longitudinal direction on the main surface of the photoelectric conversion unit, and the paste material is formed at a predetermined temperature.
  • the conductive particles so that the fusion rate of the conductive particles at the end of the photoelectric conversion unit along the longitudinal direction is lower than the fusion rate at the center of the photoelectric conversion unit along the longitudinal direction. Are fused together to form a connection electrode.
  • a solar cell according to the present invention includes a photoelectric conversion unit and a connection electrode arranged in a longitudinal direction on a main surface of the photoelectric conversion unit, and the connection electrodes are fused together to form a network structure.
  • the fusion rate of the conductive particles at the end of the photoelectric conversion unit along the longitudinal direction is such that the conductive particles at the center of the photoelectric conversion unit along the longitudinal direction It is comprised so that it may become lower than a fusion rate.
  • a solar cell according to the present invention includes a photoelectric conversion unit and a connection electrode arranged in a longitudinal direction on a main surface of the photoelectric conversion unit, and the connection electrodes are fused together to form a network structure.
  • the network structure causes aggregation peeling at the end of the photoelectric conversion part along the longitudinal direction, and the central part of the photoelectric conversion part along the longitudinal direction. It is comprised so that interface peeling may be produced in.
  • FIG. 1 it is a figure which shows the process which forms the electrode for a connection of a solar cell with the electrically conductive paste which becomes a network structure by heating.
  • FIG. 1 it is a figure which shows the process which arrange
  • FIG. 1 it is a figure which shows the process which sets a crimping
  • FIG. 1 is a flowchart showing a procedure of a method for manufacturing a solar cell module.
  • 2 to 4 are diagrams for explaining each procedure in this flowchart.
  • the solar cell module is obtained by connecting solar cells with a wiring material, a solar cell is prepared in order to manufacture the solar cell module.
  • the photoelectric conversion unit 11 is formed (S10).
  • FIG. 2 is a diagram showing the solar cell 10, FIG. 2 (a) is a plan view, and FIG. 2 (b) is a side view.
  • the solar cell 10 includes a photoelectric conversion unit 11 that generates light-generated carriers of holes and electrons by receiving light such as sunlight.
  • the solar cell 10 has, as main surfaces, a light receiving surface that is a surface on which light from the outside of the solar cell 10 is mainly incident and a back surface that is a surface opposite to the light receiving surface, but in the plan view of FIG. The light receiving surface is shown.
  • the photoelectric conversion unit 11 includes a substrate made of a semiconductor material such as crystalline silicon (c-Si), gallium arsenide (GaAs), indium phosphide (InP), for example.
  • the structure of the photoelectric conversion unit 11 is a pn junction in a broad sense.
  • a heterojunction of an n-type single crystal silicon substrate and amorphous silicon can be used.
  • a transparent conductive film (TCO) 12 composed of a conductive oxide is stacked, and an i-type amorphous silicon layer and an n-type amorphous silicon layer doped with phosphorus (P) or the like are formed on the back side of the substrate,
  • the transparent conductive film 13 can be laminated.
  • the photoelectric conversion unit 11 may have a structure other than this as long as it has a function of converting light such as sunlight into electricity.
  • a structure including a p-type polycrystalline silicon substrate, an n-type diffusion layer formed on the light-receiving surface side, and an aluminum metal film formed on the back surface side may be used.
  • connection electrode 20 on the light receiving surface side is formed on the light receiving surface of the solar cell 10.
  • the connection electrode 20 is formed by several processing procedures.
  • the conductive paste is obtained by mixing conductive particles into a resin using a solvent.
  • a conductive paste in which conductive particles such as silver (Ag) are dispersed in a binder resin can be used.
  • a sintered conductive paste that becomes a network structure by heating is used as one having improved conductivity.
  • the network structure is a structure in which conductive particles are fused to each other. For example, by heating a conductive paste containing conductive particles, the conductive particles can be fused together to form a network structure.
  • the fusion rate M (%) can be used as an index of the degree to which the conductive particles are fused to each other.
  • a certain degree of fusion rate M is required.
  • a network structure a structure having a fusion rate M of 50% or more is called a network structure.
  • the spherical powder 21 and the flakes 22 are mixed in a predetermined ratio, and a paste material mixed with a resin such as an epoxy resin using a solvent is prepared (S11).
  • the spherical powder 21 is a substantially spherical conductive particle.
  • the flakes 22 are conductive particles having a ratio of major axis to thickness of powder particles (major axis / thickness) ⁇ 10 and an average particle diameter of about 2 to 5 ⁇ m or more.
  • the flakes 22 can be obtained, for example, by crushing the spherical powder 21 into a flat shape.
  • a flake mixing ratio FR which is a ratio of the mass of the flake 22 to the total mass of the conductive particles, can be used as the mixing ratio of the spherical powder 21 and the flake 22.
  • the flake mixing ratio FR is the number of flakes 22 relative to the total number of conductive particles. It is almost the same as the number ratio.
  • a conductive paste is applied to a predetermined location on the surface of the transparent conductive film 12 on the photoelectric conversion unit 11 (S12).
  • the conductive paste is applied to the predetermined place by screen printing.
  • Heating is performed. Heating is performed by increasing the temperature at a predetermined heating rate d ⁇ (° C./s), and when the target predetermined heating temperature ⁇ (° C.) is reached, maintaining at that ⁇ for a predetermined heating time.
  • the solvent evaporates by this heating (S13).
  • the solvent evaporation rate V (m 3 / s) is controlled by the heating rate d ⁇ , the heating temperature ⁇ , the heating time, and the like.
  • the conductive particles are fused to each other by heating to form a network structure (S14). That is, when the mixture of the spherical powder 21 and the flakes 22 is heated, the spherical powders 21 are fused together to form a network structure.
  • the fusion rate M becomes higher as the heating temperature ⁇ is higher and the heating time is longer.
  • connection electrode 20 on the light receiving surface side is formed.
  • a finger electrode is disposed in addition to the bus bar electrode serving as the connection electrode 20. In FIG. 2, the finger electrode is not shown.
  • the finger electrode is a thin wire electrode that collects electricity from the entire light receiving surface but is thinned so as to reduce the light shielding property.
  • the finger electrode and the bus bar electrode are arranged orthogonally to each other and electrically connected.
  • the width of the finger electrode is preferably about 30 ⁇ m to 150 ⁇ m, and the thickness is preferably about 10 ⁇ m to 80 ⁇ m.
  • the interval between adjacent finger electrodes is preferably about 0.5 mm to 3 mm.
  • the width of the bus bar electrode as the connection electrode 20 is preferably about 50 ⁇ m to 3 mm, and the thickness is preferably about 10 ⁇ m to 160 ⁇ m.
  • connection electrode 20 on the light receiving surface side similarly to the connection electrode 20 on the light receiving surface side, a sintered conductive paste containing spherical powder and flakes and having a network structure by heating is used.
  • a connection electrode 23 on the back side is formed on the surface of the transparent conductive film 13 (S15).
  • FIG. 2B shows connection electrodes 20 and 23 formed using a sintered conductive paste containing spherical powder 21 and flakes 22 and having a network structure by heating.
  • the wiring material is arranged.
  • the wiring material 25 is arranged on the connection electrode 20 on the light receiving surface side of the solar cell 10 via the adhesive 24, and similarly, the adhesive 26 is applied on the connection electrode 23 on the back surface side of the solar cell 10.
  • the wiring member 27 is placed through the wire, and it is pressed lightly so as not to separate from each other and heated to an appropriate temperature (S16).
  • FIG. 3 is a diagram showing the solar cell module in a state where the wiring members 25 and 27 are arranged on the connection electrodes 20 and 23 via the adhesives 24 and 26, and FIG. (B) is a side view.
  • FIG. 3A shows the distinction between the end portion and the central portion of the wiring member 25, details of which will be described later.
  • the wiring members 25 and 27 are thin plates made of a metal conductive material such as copper. Instead of a thin plate, a stranded wire can be used. As the conductive material, in addition to copper, silver, aluminum, nickel, tin, gold, or an alloy thereof can be used.
  • the wiring member 25 is preferably arranged so as to cover the connection electrode 20 along the arrangement direction of the connection electrode 20 on the light receiving surface side of the solar cell 10, and the width of the wiring member 25 is set to be the connection electrode 20. It is better to set it to be the same as or slightly thicker. Similarly, the width of the wiring member 27 on the back surface side may be set to be the same as or slightly thicker than the width of the connection electrode 23 on the back surface side.
  • the adhesive 24 is disposed between the connection electrode 20 and the wiring member 25 on the light receiving surface side, electrically connects the connection electrode 20 and the wiring member 25, and the light receiving surface side of the solar cell 10 and the wiring member. 25 is used for mechanically fixing.
  • the adhesive 26 is disposed between the connection electrode 23 on the back surface side and the wiring material 27, electrically connects the connection electrode 23 and the wiring material 27, and connects the back surface side of the solar cell 10 and the wiring. Used to mechanically fix the material 27.
  • thermosetting resin adhesives such as acrylic, highly flexible polyurethane, or epoxy can be used.
  • the curing temperature ⁇ H of the adhesives 24 and 26 is selected between about 130 ° C. and 300 ° C. from the heat resistance of the solar cell 10 and the like.
  • the adhesives 24 and 26 include conductive particles.
  • conductive particles nickel, silver, nickel with gold coating, copper with tin plating, or the like can be used.
  • insulating resin adhesives that do not contain conductive particles can also be used. In this case, one or both of the facing surfaces of the wiring members 25 and 27 or the connecting electrodes 20 and 23 are made uneven so that the wiring member 27 and the connecting electrode 20 are connected. Resin is appropriately removed from between the electrodes 23 to establish electrical connection.
  • the light receiving surface side is bonded by an adhesive force between the facing surfaces of the wiring member 25 and the connection electrode 20 and an adhesive force by a resin fillet formed on the light receiving surface of the solar cell 10 and the side surface of the wiring member 25.
  • adhesion is caused by the adhesive force between the facing surfaces of the wiring member 27 and the connection electrode 23 and the adhesive force by the resin fillet formed on the light receiving surface of the solar cell 10 and the side surface of the wiring member 27. Is done.
  • the crimping process is a process of pressing the crimping tool against the solar cell 10 on which the wiring members 25 and 27 are arranged with a predetermined pressure and heating the adhesives 24 and 26 to a predetermined temperature to be cured (S17).
  • FIG. 4 is a diagram illustrating a state in which a crimping process is performed using a crimping tool.
  • the crimping tool includes a lower tool 30 and an upper tool 31 that moves up and down relatively with respect to the lower tool 30.
  • the upper tool 31 is lowered with respect to the lower tool 30 and is disposed between the lower tool 30 and the upper tool 31.
  • This is a device for applying a predetermined pressure P to the temporarily fixed solar cell.
  • the heating parts 32 and 33 are arrange
  • a resistance wire heater, a heating lamp, a heating air supply device, or the like can be used.
  • the crimping tool is a pressure heating device.
  • the heating temperature in the crimping process is set to be equal to or higher than the curing temperature of the adhesives 24 and 26.
  • the heating temperature in the crimping process is set higher as the heating time determined by the cycle time of the crimping process is shorter. For example, when the heating time can be sufficiently long, the heating temperature in the pressure-bonding process can be set as the curing temperature, but when the heating time is several seconds, the temperature is higher than the curing temperature.
  • the pressure P is preferably 0.1 MPa to 0.2 MPa.
  • the remaining process for making a solar cell module is performed (S18).
  • the solar cell module subjected to the crimping process is positioned between the light-receiving surface side protection member and the back-surface side protection member, and the filler is provided between the light-receiving surface-side protection member and the back surface-side protection member.
  • Place. Frames are arranged at the ends of the light receiving surface side protective member and the back surface side protective member.
  • a transparent plate or film is used as the protective member on the light receiving surface side.
  • a translucent member such as a glass plate, a resin plate, or a resin film can be used.
  • the protective member on the back surface side the same protective member as that on the light receiving surface side can be used.
  • an opaque plate or film can be used as the protective member on the back side.
  • a laminated film such as a resin film having an aluminum foil inside can be used.
  • EVA, EEA, PVB, silicone resin, urethane resin, acrylic resin, epoxy resin, or the like can be used.
  • connection electrode in which the conductive particles are fused to each other by heating to form a network structure
  • the solar cell module is manufactured by connecting and arranging the wiring material to the solar cell.
  • the network structure in the connection electrode is such that the conductive particles are fused to each other, so that the higher the fusion rate M of the conductive particles, the higher the conductivity.
  • the higher the fusion rate M the stronger the bonding force between the conductive particles, the stress generated between the connection electrode and the solar cell, and the stress generated between the connection electrode and the wiring material. Becomes larger. If the stress generated by this fusion becomes excessive, peeling may occur at the interface between the connection electrode and the solar cell or at the interface between the connection electrode and the wiring member. Therefore, it is necessary to appropriately control the fusion rate M in order to balance the stress generated by the improvement of conductivity and the fusion.
  • connection electrodes 20 and 23 the control of the fusion rate M of the conductive particles in the connection electrodes 20 and 23 will be described in detail with reference to FIG.
  • control is performed so that the fusion rate at the end of the solar cell is lower than the fusion rate at the center of the solar cell.
  • the fusion rate M in the central portion of the solar cell, it is preferable to secure 50% or more as the fusion rate M in order to improve the electrical conductivity.
  • the fusion rate M is made lower than that in the central portion in order to suppress delamination.
  • the fusion rate M should not be 50% or less. It is good.
  • the fusion rate M may be 50% or less, although it is not included in the network structure.
  • a peel test was performed using the solar cell 10 in which the connection electrode 20 was formed on the transparent conductive film 12.
  • the solar cell 10 having the connection electrode 20 having a fusion rate M of 50% or more at the center and a lower fusion rate M than that of the center at the end was used.
  • the peeling test was performed by applying a constant force in the vertical direction to the connecting electrode 20 and moving the cutter in the horizontal direction with respect to the connecting electrode 20 in that state.
  • the peeling mode of the connection electrode 20 is different between the central portion and the end portion. That is, the connection electrode 20 was peeled from the transparent conductive film 20 at the center.
  • the connection electrode 20 was agglomerated and peeled inside.
  • the end of the solar cell will be described. Although the positional relationship between the end portion and the center portion is shown in FIG. 3, the end portion is a region on the end face side of the solar cell 10 in the longitudinal direction of the wiring members 25 and 27.
  • the end region can be determined in consideration of the contribution of the photogenerated carriers of the solar cell 10 to the current collection. For example, with respect to the total number of finger electrodes, a region having a predetermined number counted from the end face of the solar cell 10 can be set as the end. Or it can be set as the area
  • One control for making the fusion rate at the end of the solar cell lower than the fusion rate at the center of the solar cell is the heating temperature for forming the connection electrode 20 described in S13 and S14 of FIG. This is to make ⁇ different between the end and the center.
  • the heating temperature ⁇ is set to a low temperature compared to the center portion at the end portion. It is preferable that the temperature change between the end portion and the center portion be continuously reduced from the center portion toward the end portion.
  • the degree of continuously lowering the temperature is preferably determined experimentally while observing the decrease in the fusion rate M. Depending on the experimental result, for example, the temperature may be decreased linearly toward the end portion or may be decreased in a curved manner.
  • FIG. 5 is a diagram showing this state.
  • the horizontal axis represents the solar cell position along the longitudinal direction of the wiring member.
  • the heating temperature ⁇ is set.
  • An example of ⁇ 0 is about 200 ° C.
  • the temperature can be as low as about 150 ° C.
  • the fusion rate at the end of the solar cell is made lower than the fusion rate at the center.
  • a method of varying the solvent evaporation rate V described in S13 of FIG. 1 between the end portion and the center portion can be used.
  • the solvent transpiration rate V is set to be lower than that at the center portion.
  • the change in the solvent transpiration rate V between the end portion and the center portion is preferably continuously reduced from the center portion toward the end portion.
  • the degree of continuous low speed is preferably determined experimentally while observing the decrease in the fusion rate M.
  • the solvent transpiration rate V may be decreased linearly or curvedly toward the end.
  • FIG. 6 is a diagram showing this state.
  • the horizontal axis is the solar cell position along the longitudinal direction of the wiring material, and the vertical axis is the solvent evaporation rate V.
  • the solvent evaporation rate V is set.
  • FIG. 7 is a diagram showing an example in which the solvent evaporation rate V is lowered at the end portions of the connection electrodes 20 and 23 by using a jig 34 that covers the end portions of the connection electrodes 20 and 23 and exposes the central portion. is there.
  • a white arrow 35 indicates a heating atmosphere or a ventilation atmosphere.
  • the jig 34 does not cover a central portion of the connection electrode 20 and 23, the central portion has a high heating temperature, ventilation becomes sufficient, the solvent evaporation rate V high V 0. Since the ends of the connection electrodes 20 and 23 are covered with the jig 34, the heating from the heating atmosphere is hindered, the heating temperature is lowered, and the ventilation is weak compared to the appropriate state. Since, the solvent evaporation rate V becomes gradually smaller than V 0 toward the end face side. In this way, the solvent evaporation rate V can be controlled in accordance with the solar cell position.
  • the heating rate d ⁇ for forming the connection electrode described in S14 of FIG. 1 is made different between the end portion and the center portion.
  • the heating rate d ⁇ is set to a low value compared to the center portion at the end portion. It is preferable that the change in the heating rate d ⁇ between the end portion and the center portion is continuously decreased from the center portion toward the end portion.
  • the degree of continuous lowering is preferably determined experimentally while observing the decrease in the fusion rate M. Depending on the experimental result, for example, the heating rate d ⁇ may be decreased linearly or curvedly toward the end.
  • FIG. 8 shows the state.
  • the horizontal axis is the solar cell position along the longitudinal direction of the wiring material, and the vertical axis is the heating rate d ⁇ .
  • the flake mixing ratio FR described in S11 of FIG. 1 is made different between the end portion and the center portion.
  • the flake mixing ratio FR is set to a high value as compared with the center portion.
  • the change in the flake mixing ratio FR between the end portion and the center portion is preferably continuously increased from the center portion toward the end portion.
  • the degree of continuous increase is preferably determined experimentally while observing the decrease in the fusion rate M.
  • the flake mixing ratio FR may be increased linearly toward the end or may be increased in a curved manner.
  • FIG. 9 shows the state.
  • the horizontal axis is the solar cell position along the longitudinal direction of the wiring material, and the vertical axis is the flake mixing ratio FR.
  • the flake mixing ratio FR is set.
  • the flakes 22 have an action of dividing the network structure, the flakes 22 have a function of relieving stress caused by fusion.
  • FIG. 10 is a cross-sectional view of the solar cell along the longitudinal direction of the connection electrodes 20 and 23.
  • the difference in the flake mixing ratio FR is shown by the difference in the number per unit area of the flakes 22 in the cross-sectional views of the connection electrodes 20 and 23 which are melt-aggregated.
  • the number per unit area of the flakes 22 in the end cross-sectional view is larger than the number per unit area of the flakes 22 in the central cross-sectional view.
  • the flake mixing ratio FR In order to make the flake mixing ratio FR different between the end portion and the central portion of the solar cell, at least two conductive pastes having a standard flake mixing ratio FR and a conductive paste having a flake mixing ratio FR higher than the standard are used as the conductive paste. Prepare the type in advance. Then, a conductive paste having a standard flake mixing ratio FR is applied to the central portion, and a conductive paste having a flake mixing ratio FR higher than the standard is applied to the end portion. In this way, the flake mixture ratio FR can be controlled according to the solar cell position.

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Abstract

In the procedure for this method for producing a solar cell module, a photoelectric conversion unit is formed (S10), a paste material resulting from mixing a spherical powder and flakes in a solvent is prepared (S11), the paste material is applied to the photoelectric conversion unit (S12), the solvent is heated while being caused to vaporize (S13), in parallel thereto, conductive particles are caused to fuse to each other to form a network (S14), a connecting electrode is formed (S15), a wiring material is disposed at the connecting electrode with an adhesive therebetween (S16), and the result is pressed with compressive force and heated to a predetermined temperature (S17). Then, the remaining processes to result in a solar cell module are performed (S18). The fusion rate of the conductive particles forming the network is controlled by the heating temperature for forming the connecting electrode, the vaporization speed and heating speed of the solvent, and the proportion of flake admixture.

Description

太陽電池の製造方法及び太陽電池Solar cell manufacturing method and solar cell
　本発明は、太陽電池の製造方法と、その方法によって形成された太陽電池に関する。 The present invention relates to a solar cell manufacturing method and a solar cell formed by the method.
　太陽電池の導体形成方法の一つとして、熱硬化型導電性ペーストを用いたものが知られている。この場合、熱硬化型導電性ペーストはスクリーン印刷等の手段で基体に塗布され、１００℃から３００℃程度の温度で熱処理されることにより、樹脂を硬化させ、導電性の電極が形成される。 As one of the conductor formation methods for solar cells, a method using a thermosetting conductive paste is known. In this case, the thermosetting conductive paste is applied to the substrate by means of screen printing or the like, and is heat-treated at a temperature of about 100 ° C. to 300 ° C., thereby curing the resin and forming a conductive electrode.
　特許文献１には、導電性粒子と樹脂を含む熱硬化型導電ペーストにおいて、２種以上の導電性粒子を混合して用いてもよく、導電性粒子の形状としては、球状、フレーク状、樹枝状、繊維状など制限がないが、粉末粒子同士が接触しやすく、導電性の点で有利であると述べられている。 In Patent Document 1, in a thermosetting conductive paste containing conductive particles and a resin, two or more kinds of conductive particles may be mixed and used, and the shape of the conductive particles may be spherical, flaky, or dendritic. Although there is no restriction | limiting, such as a shape and a fibrous form, it is said that powder particles are easy to contact each other and it is advantageous at an electroconductive point.
特開２００７－１５７４３４号公報JP 2007-157434 A
　導電性粒子が互いに融着してネットワーク構造を形成した接続用電極を有する太陽電池において、配線用電極における導電性の向上と融着により生じる応力とのバランスを図ることである。 In a solar cell having a connection electrode in which conductive particles are fused together to form a network structure, a balance between the improvement of conductivity in the wiring electrode and the stress caused by the fusion is achieved.
　本発明に係る太陽電池の製造方法は、導電性粒子を含むペースト材を用意し、ペースト材を光電変換部の主面上に長手方向を有するように塗布し、予め定めた所定温度でペースト材を加熱して、長手方向に沿った光電変換部の端部における導電性粒子の融着率が、長手方向に沿った光電変換部の中央部における融着率よりも低くなるように導電性粒子を互いに融着させて接続用電極を形成する。 In the method for manufacturing a solar cell according to the present invention, a paste material containing conductive particles is prepared, the paste material is applied so as to have a longitudinal direction on the main surface of the photoelectric conversion unit, and the paste material is formed at a predetermined temperature. The conductive particles so that the fusion rate of the conductive particles at the end of the photoelectric conversion unit along the longitudinal direction is lower than the fusion rate at the center of the photoelectric conversion unit along the longitudinal direction. Are fused together to form a connection electrode.
　本発明に係る太陽電池は、光電変換部と、光電変換部の主面上に長手方向を有して配置された接続用電極と、を備え、接続用電極は、互いに融着してネットワーク構造を構成する導電性粒子を含み、ネットワーク構造は、長手方向に沿った光電変換部の端部における導電性粒子の融着率が、長手方向に沿った光電変換部の中央部における導電性粒子の融着率よりも低くなるように構成されている。 A solar cell according to the present invention includes a photoelectric conversion unit and a connection electrode arranged in a longitudinal direction on a main surface of the photoelectric conversion unit, and the connection electrodes are fused together to form a network structure. In the network structure, the fusion rate of the conductive particles at the end of the photoelectric conversion unit along the longitudinal direction is such that the conductive particles at the center of the photoelectric conversion unit along the longitudinal direction It is comprised so that it may become lower than a fusion rate.
　本発明に係る太陽電池は、光電変換部と、光電変換部の主面上に長手方向を有して配置された接続用電極と、を備え、接続用電極は、互いに融着してネットワーク構造を構成する導電性粒子を含み、ネットワーク構造は、接続用電極の剥離試験において、長手方向に沿った光電変換部の端部において凝集剥離を生じさせ、長手方向に沿った光電変換部の中央部において界面剥離を生じさせるように構成されている。 A solar cell according to the present invention includes a photoelectric conversion unit and a connection electrode arranged in a longitudinal direction on a main surface of the photoelectric conversion unit, and the connection electrodes are fused together to form a network structure. In the peeling test of the connecting electrode, the network structure causes aggregation peeling at the end of the photoelectric conversion part along the longitudinal direction, and the central part of the photoelectric conversion part along the longitudinal direction. It is comprised so that interface peeling may be produced in.
　電極の部位によって導電性粒子の融着率を異ならせることで、導電性の向上と融着により生じる応力のバランスを適切なものとできる。 By making the fusion rate of the conductive particles different depending on the part of the electrode, it is possible to achieve an appropriate balance between the improvement of conductivity and the stress caused by the fusion.
本発明の実施形態における太陽電池モジュールの製造方法の手順を示すフローチャートである。It is a flowchart which shows the procedure of the manufacturing method of the solar cell module in embodiment of this invention. 図１において、加熱によりネットワーク構造となる導電ペーストにより太陽電池の接続用電極を形成する処理を示す図である。In FIG. 1, it is a figure which shows the process which forms the electrode for a connection of a solar cell with the electrically conductive paste which becomes a network structure by heating. 図１において、配線材を配置する処理を示す図である。In FIG. 1, it is a figure which shows the process which arrange | positions a wiring material. 図１において、圧着ツールをセットし、所定の加圧力で押し付け、所定温度で加熱する処理を示す図である。In FIG. 1, it is a figure which shows the process which sets a crimping | compression-bonding tool, presses with a predetermined pressurizing force, and heats it at a predetermined temperature. 本発明の実施形態の太陽電池モジュールの製造方法において、加熱温度と融着率の関係を示す図である。It is a figure which shows the relationship between heating temperature and a fusion rate in the manufacturing method of the solar cell module of embodiment of this invention. 本発明の実施形態の太陽電池モジュールの製造方法において、太陽電池位置と溶剤蒸散速度の関係を示す図である。It is a figure which shows the relationship between a solar cell position and a solvent evaporation rate in the manufacturing method of the solar cell module of embodiment of this invention. 本発明の実施形態の太陽電池モジュールの製造方法において、太陽電池位置の端部の溶剤蒸散速度を低くする方法を示す図である。In the manufacturing method of the solar cell module of embodiment of this invention, it is a figure which shows the method of making the solvent evaporation rate of the edge part of a solar cell position low. 本発明の実施形態の太陽電池モジュールの製造方法において、太陽電池位置と加熱速度の関係を示す図である。In the manufacturing method of the solar cell module of embodiment of this invention, it is a figure which shows the relationship between a solar cell position and a heating rate. 本発明の実施形態の太陽電池モジュールの製造方法において、太陽電池位置とフレーク混合比の関係を示す図である。It is a figure which shows the relationship between a solar cell position and flake mixing ratio in the manufacturing method of the solar cell module of embodiment of this invention. 本発明の実施形態の太陽電池において、太陽電池位置によってフレーク混合比が異なることを示す断面図である。In the solar cell of embodiment of this invention, it is sectional drawing which shows that flake mixing ratios change with solar cell positions.
　以下に図面を用いて、本発明の実施の形態を詳細に説明する。以下で述べる温度、加圧力、寸法等は説明のための例示であって、太陽電池モジュールの仕様に応じ、適宜変更が可能である。以下では、全ての図面において一または対応する要素には同一の符号を付し、重複する説明を省略する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The temperature, pressure, dimensions, and the like described below are illustrative examples, and can be appropriately changed according to the specifications of the solar cell module. Hereinafter, in all the drawings, one or the corresponding element is denoted by the same reference numeral, and redundant description is omitted.
　図１は、太陽電池モジュールの製造方法の手順を示すフローチャートである。図２から図４は、このフローチャートにおける各手順を説明する図である。 FIG. 1 is a flowchart showing a procedure of a method for manufacturing a solar cell module. 2 to 4 are diagrams for explaining each procedure in this flowchart.
　太陽電池モジュールは、太陽電池を配線材で接続したものであるので、太陽電池モジュールを製造するには、太陽電池を準備する。太陽電池の準備のためには、まず光電変換部１１を形成する（Ｓ１０）。 Since the solar cell module is obtained by connecting solar cells with a wiring material, a solar cell is prepared in order to manufacture the solar cell module. In order to prepare the solar cell, first, the photoelectric conversion unit 11 is formed (S10).
　図２は、太陽電池１０を示す図で、図２（ａ）は平面図、（ｂ）は側面図である。太陽電池１０は、太陽光等の光を受光することで正孔および電子の光生成キャリアを生成する光電変換部１１を備える。太陽電池１０は、主面として、太陽電池１０の外部からの光が主に入射する面である受光面と、受光面と反対側の面である裏面とを有するが、図２の平面図では受光面が示されている。 FIG. 2 is a diagram showing the solar cell 10, FIG. 2 (a) is a plan view, and FIG. 2 (b) is a side view. The solar cell 10 includes a photoelectric conversion unit 11 that generates light-generated carriers of holes and electrons by receiving light such as sunlight. The solar cell 10 has, as main surfaces, a light receiving surface that is a surface on which light from the outside of the solar cell 10 is mainly incident and a back surface that is a surface opposite to the light receiving surface, but in the plan view of FIG. The light receiving surface is shown.
　光電変換部１１は、例えば、結晶性シリコン（ｃ－Ｓｉ）、ガリウム砒素（ＧａＡｓ）、インジウム燐（ＩｎＰ）等の半導体材料の基板を有する。光電変換部１１の構造は、広義のｐｎ接合である。例えば、ｎ型単結晶シリコン基板と非晶質シリコンのヘテロ接合を用いることができる。この場合、受光面側の基板上に、ｉ型非晶質シリコン層と、ボロン（Ｂ）等がドープされたｐ型非晶質シリコン層と、酸化インジウム（Ｉｎ2Ｏ3）の透光性導電酸化物で構成される透明導電膜（ＴＣＯ）１２を積層し、基板の裏面側に、ｉ型非晶質シリコン層と、燐（Ｐ）等がドープされたｎ型非晶質シリコン層と、透明導電膜１３を積層する構造とできる。 The photoelectric conversion unit 11 includes a substrate made of a semiconductor material such as crystalline silicon (c-Si), gallium arsenide (GaAs), indium phosphide (InP), for example. The structure of the photoelectric conversion unit 11 is a pn junction in a broad sense. For example, a heterojunction of an n-type single crystal silicon substrate and amorphous silicon can be used. In this case, an i-type amorphous silicon layer, a p-type amorphous silicon layer doped with boron (B) or the like, and indium oxide (In 2 O 3 ) translucency on the substrate on the light-receiving surface side. A transparent conductive film (TCO) 12 composed of a conductive oxide is stacked, and an i-type amorphous silicon layer and an n-type amorphous silicon layer doped with phosphorus (P) or the like are formed on the back side of the substrate, The transparent conductive film 13 can be laminated.
　光電変換部１１は、太陽光等の光を電気に変換する機能を有すれば、これ以外の構造であってもよい。例えば、ｐ型多結晶シリコン基板と、その受光面側に形成されたｎ型拡散層と、その裏面側に形成されたアルミニウム金属膜とを備える構造であってもよい。 The photoelectric conversion unit 11 may have a structure other than this as long as it has a function of converting light such as sunlight into electricity. For example, a structure including a p-type polycrystalline silicon substrate, an n-type diffusion layer formed on the light-receiving surface side, and an aluminum metal film formed on the back surface side may be used.
　図１に戻り、光電変換部１１が形成されると、太陽電池１０の受光面に受光面側の接続用電極２０が形成される。接続用電極２０の形成は、いくつかの処理手順によって行われる。 1, when the photoelectric conversion unit 11 is formed, the connection electrode 20 on the light receiving surface side is formed on the light receiving surface of the solar cell 10. The connection electrode 20 is formed by several processing procedures.
　まず、導電性ペーストを準備する。導電ペーストは、溶剤を用いて導電性粒子を樹脂に混入させたものである。導電ペーストとしては様々な種類があり、用途に応じて使い分けることができる。例えば、バインダ樹脂中に銀（Ａｇ）等の導電性粒子が分散された導電性ペーストを用いることができる。ここでは、導電性を向上させたものとして、加熱によりネットワーク構造となる焼結型導電ペーストを用いる。 First, prepare a conductive paste. The conductive paste is obtained by mixing conductive particles into a resin using a solvent. There are various types of conductive pastes, which can be used properly according to the application. For example, a conductive paste in which conductive particles such as silver (Ag) are dispersed in a binder resin can be used. Here, a sintered conductive paste that becomes a network structure by heating is used as one having improved conductivity.
　ネットワーク構造は、導電性粒子が互いに融着した構造である。例えば、導電性粒子を含む導電性ペーストを加熱することで、導電性粒子を互いに融着させてネットワーク構造を形成することができる。導電性粒子が互いに融着している程度の指標としての融着率Ｍ（％）を用いることができる。融着率Ｍは、例えば、顕微鏡下で導電性粒子を観察して、視野の中の導電性粒子の総数をＮとし、隣接する導電性粒子と融着している導電性粒子の数をｎとして、融着率Ｍ＝（ｎ／Ｎ）×１００％とすることができる。ネットワーク構造と呼ぶためにはある程度の融着率Ｍが必要である。以下では融着率Ｍが５０％以上の構造をネットワーク構造と呼ぶことにして説明を続ける。 The network structure is a structure in which conductive particles are fused to each other. For example, by heating a conductive paste containing conductive particles, the conductive particles can be fused together to form a network structure. The fusion rate M (%) can be used as an index of the degree to which the conductive particles are fused to each other. The fusion rate M is determined by, for example, observing the conductive particles under a microscope, N is the total number of conductive particles in the field of view, and n is the number of conductive particles fused with the adjacent conductive particles. As described above, the fusion rate M = (n / N) × 100%. In order to call it a network structure, a certain degree of fusion rate M is required. Hereinafter, the description will be continued assuming that a structure having a fusion rate M of 50% or more is called a network structure.
　そこで、加熱によりネットワーク構造を形成するために、球状粉２１とフレーク２２とを予め定めた割合で混合し、溶剤を用いてエポキシ樹脂等の樹脂と混ぜ合わせたペースト材を準備する（Ｓ１１）。 Therefore, in order to form a network structure by heating, the spherical powder 21 and the flakes 22 are mixed in a predetermined ratio, and a paste material mixed with a resin such as an epoxy resin using a solvent is prepared (S11).
　球状粉２１は、ほぼ球状の導電性の粒子である。フレーク２２は、粉末粒子の長径と厚さの比が（長径／厚さ）≧１０であり、平均粒子径が約２～５μｍ以上の導電性粒子のことをいう。フレーク２２は、例えば、球状粉２１を押しつぶして扁平な形状とすることで得ることができる。球状粉２１とフレーク２２の混合比を示すものとして、導電性粒子の全質量に対するフレーク２２の質量の比であるフレーク混合比ＦＲを用いることができる。球状粉２１をそのまま押しつぶしてフレーク２２とするときは、１つの球状粉２１の質量と１つのフレーク２２の質量はほぼ同じであるので、フレーク混合比ＦＲは、導電性粒子の総数に対するフレーク２２の数の比とほぼ同じである。 The spherical powder 21 is a substantially spherical conductive particle. The flakes 22 are conductive particles having a ratio of major axis to thickness of powder particles (major axis / thickness) ≧ 10 and an average particle diameter of about 2 to 5 μm or more. The flakes 22 can be obtained, for example, by crushing the spherical powder 21 into a flat shape. A flake mixing ratio FR, which is a ratio of the mass of the flake 22 to the total mass of the conductive particles, can be used as the mixing ratio of the spherical powder 21 and the flake 22. When the spherical powder 21 is crushed into the flakes 22 as they are, the mass of one spherical powder 21 and the mass of one flake 22 are almost the same, so the flake mixing ratio FR is the number of flakes 22 relative to the total number of conductive particles. It is almost the same as the number ratio.
　次に、光電変換部１１の上の透明導電膜１２の表面の所定の箇所に導電ペーストを塗布する（Ｓ１２）。所定の箇所に導電ペーストを塗布するのは、スクリーン印刷によって行われる。 Next, a conductive paste is applied to a predetermined location on the surface of the transparent conductive film 12 on the photoelectric conversion unit 11 (S12). The conductive paste is applied to the predetermined place by screen printing.
　透明導電膜１２の上に導電ペーストが塗布されると、加熱が行われる。加熱は、所定の加熱速度ｄθ（℃／ｓ）で昇温し、目標の所定加熱温度θ（℃）に到達したら、所定の加熱時間の間そのθで維持することで行われる。この加熱によって溶剤が蒸散する（Ｓ１３）。溶剤蒸散速度Ｖ（ｍ3／ｓ）は、加熱速度ｄθ、加熱温度θ、加熱時間等によって制御される。 When the conductive paste is applied on the transparent conductive film 12, heating is performed. Heating is performed by increasing the temperature at a predetermined heating rate dθ (° C./s), and when the target predetermined heating temperature θ (° C.) is reached, maintaining at that θ for a predetermined heating time. The solvent evaporates by this heating (S13). The solvent evaporation rate V (m 3 / s) is controlled by the heating rate dθ, the heating temperature θ, the heating time, and the like.
　溶剤の蒸散と並行して、加熱によって導電性粒子が互いに融着してネットワーク構造を形成する（Ｓ１４）。すなわち、球状粉２１とフレーク２２の混合物を加熱すると、球状粉２１が互いに融着して、ネットワーク構造を形成する。融着率Ｍは、加熱温度θが高く、加熱時間が長いほど、高い値となる。 In parallel with the evaporation of the solvent, the conductive particles are fused to each other by heating to form a network structure (S14). That is, when the mixture of the spherical powder 21 and the flakes 22 is heated, the spherical powders 21 are fused together to form a network structure. The fusion rate M becomes higher as the heating temperature θ is higher and the heating time is longer.
　このようにして、受光面側の接続用電極２０が形成される。なお、太陽電池１０の受光面に光生成キャリアを集電するために設けられる受光面電極としては、接続用電極２０として働くバスバー電極の他に、フィンガ電極が配置される。図２では、フィンガ電極の図示を省略した。 In this way, the connection electrode 20 on the light receiving surface side is formed. As the light receiving surface electrode provided for collecting the photogenerated carriers on the light receiving surface of the solar cell 10, a finger electrode is disposed in addition to the bus bar electrode serving as the connection electrode 20. In FIG. 2, the finger electrode is not shown.
　フィンガ電極は、受光面の全体から集電するが、遮光性を少なくするように、細線化した細線電極である。フィンガ電極とバスバー電極は、互いに直交して配置されて電気的に接続される。フィンガ電極の幅としては３０μｍから１５０μｍ程度が好ましく、厚さは１０μｍから８０μｍ程度が好ましい。隣接するフィンガ電極の間隔は、０．５ｍｍから３ｍｍ程度が好ましい。接続用電極２０であるバスバー電極の幅としては５０μｍから３ｍｍ程度が好ましく、厚さは１０μｍから１６０μｍ程度が好ましい。 The finger electrode is a thin wire electrode that collects electricity from the entire light receiving surface but is thinned so as to reduce the light shielding property. The finger electrode and the bus bar electrode are arranged orthogonally to each other and electrically connected. The width of the finger electrode is preferably about 30 μm to 150 μm, and the thickness is preferably about 10 μm to 80 μm. The interval between adjacent finger electrodes is preferably about 0.5 mm to 3 mm. The width of the bus bar electrode as the connection electrode 20 is preferably about 50 μm to 3 mm, and the thickness is preferably about 10 μm to 160 μm.
　太陽電池１０の裏面においても、受光面側の接続用電極２０と同様に、球状粉とフレークを含み、加熱によりネットワーク構造となる焼結型導電ペーストを用いて、光電変換部１１の裏面側の透明導電膜１３の表面に裏面側の接続用電極２３が形成される（Ｓ１５）。図２（ｂ）には、球状粉２１とフレーク２２を含み、加熱によりネットワーク構造となる焼結型導電ペーストを用いて形成された接続用電極２０，２３が示されている。 Also on the back surface of the solar cell 10, similarly to the connection electrode 20 on the light receiving surface side, a sintered conductive paste containing spherical powder and flakes and having a network structure by heating is used. A connection electrode 23 on the back side is formed on the surface of the transparent conductive film 13 (S15). FIG. 2B shows connection electrodes 20 and 23 formed using a sintered conductive paste containing spherical powder 21 and flakes 22 and having a network structure by heating.
　再び図１に戻り、次に、配線材の配置が行われる。配線材の配置は、太陽電池１０の受光面側の接続用電極２０に接着剤２４を介して配線材２５を配置し、同様に、太陽電池１０の裏面側の接続用電極２３に接着剤２６を介して配線材２７を配置し、互いに分離しないように、軽く押え、適当な温度に加熱して行われる（Ｓ１６）。 Returning to FIG. 1 again, next, the wiring material is arranged. As for the arrangement of the wiring material, the wiring material 25 is arranged on the connection electrode 20 on the light receiving surface side of the solar cell 10 via the adhesive 24, and similarly, the adhesive 26 is applied on the connection electrode 23 on the back surface side of the solar cell 10. The wiring member 27 is placed through the wire, and it is pressed lightly so as not to separate from each other and heated to an appropriate temperature (S16).
　図３は、接続用電極２０，２３に対し接着剤２４，２６を介して配線材２５，２７の配置が行われた状態の太陽電池モジュールを示す図で、図３（ａ）は平面図、（ｂ）は側面図である。なお、図３（ａ）には、配線材２５の端部と中央部の区別が示されているが、その詳細については後述する。 FIG. 3 is a diagram showing the solar cell module in a state where the wiring members 25 and 27 are arranged on the connection electrodes 20 and 23 via the adhesives 24 and 26, and FIG. (B) is a side view. FIG. 3A shows the distinction between the end portion and the central portion of the wiring member 25, details of which will be described later.
　配線材２５，２７は、銅等の金属導電性材料で構成される薄板である。薄板に代えて撚り線状のものを用いることもできる。導電性材料としては、銅の他に、銀、アルミニウム、ニッケル、錫、金、あるいはこれらの合金を用いることができる。配線材２５は、太陽電池１０の受光面側の接続用電極２０の配置方向に沿って、接続用電極２０を覆うように配置されることが好ましく、配線材２５の幅は、接続用電極２０の幅と同じか、やや太めに設定するとよい。同様に、裏面側の配線材２７の幅は、裏面側の接続用電極２３の幅と同じか、やや太めに設定するとよい。 The wiring members 25 and 27 are thin plates made of a metal conductive material such as copper. Instead of a thin plate, a stranded wire can be used. As the conductive material, in addition to copper, silver, aluminum, nickel, tin, gold, or an alloy thereof can be used. The wiring member 25 is preferably arranged so as to cover the connection electrode 20 along the arrangement direction of the connection electrode 20 on the light receiving surface side of the solar cell 10, and the width of the wiring member 25 is set to be the connection electrode 20. It is better to set it to be the same as or slightly thicker. Similarly, the width of the wiring member 27 on the back surface side may be set to be the same as or slightly thicker than the width of the connection electrode 23 on the back surface side.
　接着剤２４は、受光面側の接続用電極２０と配線材２５との間に配置され、接続用電極２０と配線材２５とを電気的に接続し、太陽電池１０の受光面側と配線材２５とを機械的に固定するために用いられる。同様に、接着剤２６は、裏面側の接続用電極２３と配線材２７との間に配置され、接続用電極２３と配線材２７とを電気的に接続し、太陽電池１０の裏面側と配線材２７とを機械的に固定するために用いられる。 The adhesive 24 is disposed between the connection electrode 20 and the wiring member 25 on the light receiving surface side, electrically connects the connection electrode 20 and the wiring member 25, and the light receiving surface side of the solar cell 10 and the wiring member. 25 is used for mechanically fixing. Similarly, the adhesive 26 is disposed between the connection electrode 23 on the back surface side and the wiring material 27, electrically connects the connection electrode 23 and the wiring material 27, and connects the back surface side of the solar cell 10 and the wiring. Used to mechanically fix the material 27.
　接着剤２４，２６としては、アクリル系、柔軟性の高いポリウレタン系、あるいはエポキシ系等の熱硬化性樹脂接着剤を用いることができる。接着剤２４，２６の硬化温度θHは、太陽電池１０の耐熱性等から、約１３０℃～３００℃の間で選定される。 As the adhesives 24 and 26, thermosetting resin adhesives such as acrylic, highly flexible polyurethane, or epoxy can be used. The curing temperature θ H of the adhesives 24 and 26 is selected between about 130 ° C. and 300 ° C. from the heat resistance of the solar cell 10 and the like.
　接着剤２４，２６には、導電性粒子が含まれる。導電性粒子としては、ニッケル、銀、金コート付ニッケル、錫メッキ付銅等を用いることができる。接着剤２４，２６として、導電性粒子を含まない絶縁性の樹脂接着剤を用いることもできる。この場合には、配線材２５，２７または接続用電極２０，２３の互いに対向する面のいずれか一方または双方を凹凸化して、配線材２５と接続用電極２０の間、配線材２７と接続用電極２３の間から樹脂を適当に排除して電気的接続を取るようにする。受光面側は、配線材２５と接続用電極２０の向かい合う面の間の接着力と、太陽電池１０の受光面と配線材２５の側面に形成される樹脂のフィレットによる接着力によって接着される。同様に、裏面側においても、配線材２７と接続用電極２３の向かい合う面の間の接着力と、太陽電池１０の受光面と配線材２７の側面に形成される樹脂のフィレットによる接着力によって接着される。 The adhesives 24 and 26 include conductive particles. As the conductive particles, nickel, silver, nickel with gold coating, copper with tin plating, or the like can be used. As the adhesives 24 and 26, insulating resin adhesives that do not contain conductive particles can also be used. In this case, one or both of the facing surfaces of the wiring members 25 and 27 or the connecting electrodes 20 and 23 are made uneven so that the wiring member 27 and the connecting electrode 20 are connected. Resin is appropriately removed from between the electrodes 23 to establish electrical connection. The light receiving surface side is bonded by an adhesive force between the facing surfaces of the wiring member 25 and the connection electrode 20 and an adhesive force by a resin fillet formed on the light receiving surface of the solar cell 10 and the side surface of the wiring member 25. Similarly, also on the back surface side, adhesion is caused by the adhesive force between the facing surfaces of the wiring member 27 and the connection electrode 23 and the adhesive force by the resin fillet formed on the light receiving surface of the solar cell 10 and the side surface of the wiring member 27. Is done.
　再び図1に戻り、配線材の配置処理が終わると、次に、圧着処理が行われる。圧着処理は、配線材２５，２７が配置された太陽電池１０に対し、圧着ツールを所定の加圧力で押し付け、接着剤２４，２６を所定温度に加熱して硬化させる処理である（Ｓ１７）。 Referring back to FIG. 1 again, after the wiring material placement process is completed, the crimping process is performed. The crimping process is a process of pressing the crimping tool against the solar cell 10 on which the wiring members 25 and 27 are arranged with a predetermined pressure and heating the adhesives 24 and 26 to a predetermined temperature to be cured (S17).
　図４は、圧着ツールを用いて圧着処理が行われる様子を示す図である。圧着ツールは、下ツール３０と、下ツール３０に対し相対的に昇降する上ツール３１を含み、下ツール３０に対し上ツール３１を下降させて、下ツール３０と上ツール３１の間に配置された仮止め状態の太陽電池に所定の加圧力Ｐを印加する装置である。また、下ツール３０と上ツール３１にはそれぞれ加熱部３２，３３が配置され、仮止め状態の太陽電池が所定の加熱温度で加熱される。加熱部３２，３３としては、抵抗線ヒータ、加熱ランプ、加熱風供給装置等を用いることができる。このように、圧着ツールは、加圧加熱装置である。 FIG. 4 is a diagram illustrating a state in which a crimping process is performed using a crimping tool. The crimping tool includes a lower tool 30 and an upper tool 31 that moves up and down relatively with respect to the lower tool 30. The upper tool 31 is lowered with respect to the lower tool 30 and is disposed between the lower tool 30 and the upper tool 31. This is a device for applying a predetermined pressure P to the temporarily fixed solar cell. Moreover, the heating parts 32 and 33 are arrange | positioned at the lower tool 30 and the upper tool 31, respectively, and the solar cell of a temporarily fixed state is heated at predetermined heating temperature. As the heating units 32 and 33, a resistance wire heater, a heating lamp, a heating air supply device, or the like can be used. Thus, the crimping tool is a pressure heating device.
　圧着処理における加熱温度は、接着剤２４，２６の硬化温度以上に設定する。圧着処理における加熱温度は、圧着処理のサイクルタイムで定まる加熱時間が短いほど高温に設定される。例えば、加熱時間を十分長く取れるときは、圧着処理における加熱温度を硬化温度とできるが、加熱時間が数秒のときは、硬化温度よりも高い温度とする。加圧力Ｐとしては０．１ＭＰａ～０．２ＭＰａとすることがよい。 The heating temperature in the crimping process is set to be equal to or higher than the curing temperature of the adhesives 24 and 26. The heating temperature in the crimping process is set higher as the heating time determined by the cycle time of the crimping process is shorter. For example, when the heating time can be sufficiently long, the heating temperature in the pressure-bonding process can be set as the curing temperature, but when the heating time is several seconds, the temperature is higher than the curing temperature. The pressure P is preferably 0.1 MPa to 0.2 MPa.
　再び図１に戻り、圧着処理が終了すると、太陽電池モジュールとするための残りの処理が行われる（Ｓ１８）。ここでは、受光面側の保護部材と、裏面側の保護部材の間に、圧着処理が終わった太陽電池モジュールを位置決めし、受光面側の保護部材と、裏面側の保護部材の間に充填材を配置する。受光面側の保護部材および裏面側の保護部材の端部には、フレームが配置される。 Referring back to FIG. 1 again, when the crimping process is completed, the remaining process for making a solar cell module is performed (S18). Here, the solar cell module subjected to the crimping process is positioned between the light-receiving surface side protection member and the back-surface side protection member, and the filler is provided between the light-receiving surface-side protection member and the back surface-side protection member. Place. Frames are arranged at the ends of the light receiving surface side protective member and the back surface side protective member.
　受光面側の保護部材としては、透明な板体、フィルムが用いられる。例えば、ガラス板、樹脂板、樹脂フィルム等の透光性を有する部材を用いることができる。裏面側の保護部材は、受光面側の保護部材と同じものを用いることができる。裏面側からの受光を必要としない構造の太陽電池モジュールの場合は、裏面側の保護部材として、不透明な板体やフィルムを用いることができる。例えば、アルミ箔を内部に有する樹脂フィルム等の積層フィルムを用いることができる。充填材は、ＥＶＡ、ＥＥＡ、ＰＶＢ、シリコーン系樹脂、ウレタン系樹脂、アクリル系樹脂、エポキシ系樹脂等を用いることができる。 A transparent plate or film is used as the protective member on the light receiving surface side. For example, a translucent member such as a glass plate, a resin plate, or a resin film can be used. As the protective member on the back surface side, the same protective member as that on the light receiving surface side can be used. In the case of a solar cell module having a structure that does not require light reception from the back side, an opaque plate or film can be used as the protective member on the back side. For example, a laminated film such as a resin film having an aluminum foil inside can be used. As the filler, EVA, EEA, PVB, silicone resin, urethane resin, acrylic resin, epoxy resin, or the like can be used.
　このようにして、加熱により導電性粒子が互いに融着してネットワーク構造を形成した接続用電極を用いた太陽電池が形成され、その太陽電池に配線材を接続配置して太陽電池モジュールが製造される。接続用電極におけるネットワーク構造は、導電性粒子が互いに融着したものであるので、導電性粒子の融着率Ｍが高いほど導電率が向上する。一方で、融着率Ｍが高いほど、導電性粒子同士の結合力が強くなり、接続用電極と太陽電池との間に発生する応力や、接続用電極と配線材との間に発生する応力が大きくなる。この融着により生じる応力が過大になると、接続用電極と太陽電池との間の界面や接続用電極と配線材との間の界面で剥離が生じ得る。したがって、導電性の向上と融着により生じる応力のバランスを図るために、融着率Ｍを適切に制御することが必要である。 In this way, a solar cell using the connection electrode in which the conductive particles are fused to each other by heating to form a network structure is formed, and the solar cell module is manufactured by connecting and arranging the wiring material to the solar cell. The The network structure in the connection electrode is such that the conductive particles are fused to each other, so that the higher the fusion rate M of the conductive particles, the higher the conductivity. On the other hand, the higher the fusion rate M, the stronger the bonding force between the conductive particles, the stress generated between the connection electrode and the solar cell, and the stress generated between the connection electrode and the wiring material. Becomes larger. If the stress generated by this fusion becomes excessive, peeling may occur at the interface between the connection electrode and the solar cell or at the interface between the connection electrode and the wiring member. Therefore, it is necessary to appropriately control the fusion rate M in order to balance the stress generated by the improvement of conductivity and the fusion.
　そこで、接続用電極２０，２３における導電性粒子の融着率Ｍの制御について、図５以下を用いて詳細に説明する。ここでは、融着により生じる応力が過大になると、接続用電極と太陽電池との間の界面や接続用電極と配線材との間の界面で剥離が生じ得ることに着目し、特に、太陽電池と配線材との接続にとって重要な個所である太陽電池の端部において剥離を生じさせないようにする。そのために、太陽電池の端部における融着率を、太陽電池の中央部における融着率よりも低くする制御を行う。 Therefore, the control of the fusion rate M of the conductive particles in the connection electrodes 20 and 23 will be described in detail with reference to FIG. Here, focusing on the fact that if the stress caused by fusion becomes excessive, delamination may occur at the interface between the connection electrode and the solar cell or at the interface between the connection electrode and the wiring material. It is made to prevent peeling at the end portion of the solar cell, which is an important part for connection between the wiring member and the wiring member. Therefore, control is performed so that the fusion rate at the end of the solar cell is lower than the fusion rate at the center of the solar cell.
　ここで、太陽電池の中央部では、導電率の向上を図るため、融着率Ｍとして５０％以上を確保することがよい。端部では、剥離抑制のために中央部に比較して融着率Ｍを低くするが、導電率を確保することが必要な場合には、融着率Ｍを５０％以下とならないようにすることがよい。導電率を犠牲にして剥離抑制を優先する場合には、ネットワーク構造の目安からは外れるが、融着率Ｍを５０％以下としてもよい。 Here, in the central portion of the solar cell, it is preferable to secure 50% or more as the fusion rate M in order to improve the electrical conductivity. At the end portion, the fusion rate M is made lower than that in the central portion in order to suppress delamination. However, if it is necessary to ensure conductivity, the fusion rate M should not be 50% or less. It is good. In the case where priority is given to suppression of peeling at the expense of conductivity, the fusion rate M may be 50% or less, although it is not included in the network structure.
　図２に示すように、透明導電膜１２上に接続用電極２０を形成した太陽電池１０を用いて剥離試験を行った。この試験においては、中央部では融着率Ｍを５０％以上とし、端部では中央部よりも融着率Ｍを低くした接続電極２０を有する太陽電池１０を用いた。剥離試験は、カッターを接続用電極２０に対して垂直方向に一定の力を加え、その状態でカッターを接続用電極２０に対して水平方向に動かすことによって行った。この結果、接続用電極２０の剥離モードは、中央部と端部とで異なるものとなった。すなわち、中央部において、接続用電極２０は、透明導電膜２０から界面剥離した。一方、端部においては、接続用電極２０はその内部で凝集剥離した。 As shown in FIG. 2, a peel test was performed using the solar cell 10 in which the connection electrode 20 was formed on the transparent conductive film 12. In this test, the solar cell 10 having the connection electrode 20 having a fusion rate M of 50% or more at the center and a lower fusion rate M than that of the center at the end was used. The peeling test was performed by applying a constant force in the vertical direction to the connecting electrode 20 and moving the cutter in the horizontal direction with respect to the connecting electrode 20 in that state. As a result, the peeling mode of the connection electrode 20 is different between the central portion and the end portion. That is, the connection electrode 20 was peeled from the transparent conductive film 20 at the center. On the other hand, at the end, the connection electrode 20 was agglomerated and peeled inside.
　ここで、太陽電池の端部について説明する。図３で端部と中央部の位置関係を示したが、端部は、配線材２５，２７の長手方向において、太陽電池１０の端面側の領域である。端部の領域は、太陽電池１０の光生成キャリアの集電に対する寄与を考慮して定めることができる。例えば、フィンガ電極の総本数に対し、太陽電池１０の端面から数えて予め定めた本数となる領域を端部とすることができる。あるいは、太陽電池１０の端面から内側に予め定めた幅の領域とすることができる。一例として、太陽電池１０の端面から内側に約２０ｍｍを端部とすることができる。この数字は一例であって、太陽電池１０の仕様に応じて変更できる。 Here, the end of the solar cell will be described. Although the positional relationship between the end portion and the center portion is shown in FIG. 3, the end portion is a region on the end face side of the solar cell 10 in the longitudinal direction of the wiring members 25 and 27. The end region can be determined in consideration of the contribution of the photogenerated carriers of the solar cell 10 to the current collection. For example, with respect to the total number of finger electrodes, a region having a predetermined number counted from the end face of the solar cell 10 can be set as the end. Or it can be set as the area | region of the predetermined width inside from the end surface of the solar cell 10. FIG. As an example, about 20 mm can be made into an edge part from the end surface of the solar cell 10 inside. This number is an example and can be changed according to the specifications of the solar cell 10.
　太陽電池の端部における融着率を、太陽電池の中央部における融着率よりも低くする制御の１つは、図１のＳ１３，Ｓ１４で説明した接続用電極２０の形成のための加熱温度θを端部と中央部で異ならせることである。加熱温度θは、端部を中央部に比較して低温にする。端部と中央部との間の温度変化は、中央部から端部に向かって連続的に低温とすることがよい。連続的に低温にする程度は、これによる融着率Ｍの低下を見ながら実験的に定めることがよい。実験結果によって、例えば、端部に向かって温度を直線的に低下するようにしてもよく、曲線的に低下するようにしてもよい。 One control for making the fusion rate at the end of the solar cell lower than the fusion rate at the center of the solar cell is the heating temperature for forming the connection electrode 20 described in S13 and S14 of FIG. This is to make θ different between the end and the center. The heating temperature θ is set to a low temperature compared to the center portion at the end portion. It is preferable that the temperature change between the end portion and the center portion be continuously reduced from the center portion toward the end portion. The degree of continuously lowering the temperature is preferably determined experimentally while observing the decrease in the fusion rate M. Depending on the experimental result, for example, the temperature may be decreased linearly toward the end portion or may be decreased in a curved manner.
　図５はその様子を示す図である。これらの図において、横軸は配線材の長手方向に沿った太陽電池位置である。図５（ａ）の縦軸は加熱温度θで、太陽電池の中央部ではθ＝θ0の一定値に設定され、端部では、太陽電池の端面側に向かってθ0から徐々に低くなるように加熱温度θが設定される。θ0の例としては約２００℃である。端部では、約１５０℃程度の低温とすることができる。 FIG. 5 is a diagram showing this state. In these drawings, the horizontal axis represents the solar cell position along the longitudinal direction of the wiring member. The vertical axis in FIG. 5A is the heating temperature θ, which is set to a constant value of θ = θ 0 at the center of the solar cell, and gradually decreases from θ 0 toward the end face of the solar cell at the end. Thus, the heating temperature θ is set. An example of θ 0 is about 200 ° C. At the end, the temperature can be as low as about 150 ° C.
　図５（ｂ）の縦軸は、融着率Ｍで、加熱温度θの設定に対応して、太陽電池の中央部ではＭ＝Ｍ0の一定値であるが、端部では、融着率Ｍが太陽電池の端面側に向かってＭ0から徐々に低くなる。 The vertical axis of FIG. 5B is the fusion rate M, which corresponds to the setting of the heating temperature θ, which is a constant value of M = M 0 at the center of the solar cell, but at the end, the fusion rate. M gradually decreases from M 0 toward the end face of the solar cell.
　このように、接続用電極の形成のための加熱温度θを制御することで、太陽電池の端部における融着率を中央部の融着率より低くする。これによって、太陽電池の端部において、接続用電極形成の融着によって生じる応力を低減でき、その応力によって発生し得る剥離を抑制できる。 Thus, by controlling the heating temperature θ for forming the connection electrode, the fusion rate at the end of the solar cell is made lower than the fusion rate at the center. As a result, at the end of the solar cell, it is possible to reduce the stress caused by the fusion of the connection electrode formation, and to suppress peeling that may occur due to the stress.
　融着率制御として、図１のＳ１３で説明した溶剤蒸散速度Ｖを端部と中央部で異ならせる方法を用いることができる。溶剤蒸散速度Ｖは、端部を中央部に比較して低速にする。端部と中央部との間の溶剤蒸散速度Ｖの変化は、中央部から端部に向かって連続的に低速とすることがよい。連続的に低速にする程度は、これによる融着率Ｍの低下を見ながら実験的に定めることがよい。実験結果によって、例えば、端部に向かって溶剤蒸散速度Ｖを直線的に低下するようにしてもよく、曲線的に低下するようにしてもよい。 As the fusion rate control, a method of varying the solvent evaporation rate V described in S13 of FIG. 1 between the end portion and the center portion can be used. The solvent transpiration rate V is set to be lower than that at the center portion. The change in the solvent transpiration rate V between the end portion and the center portion is preferably continuously reduced from the center portion toward the end portion. The degree of continuous low speed is preferably determined experimentally while observing the decrease in the fusion rate M. Depending on the experimental result, for example, the solvent transpiration rate V may be decreased linearly or curvedly toward the end.
　図６はその様子を示す図である。横軸は配線材の長手方向に沿った太陽電池位置で、縦軸は溶剤蒸散速度Ｖである。図６に示されるように、溶剤蒸散速度Ｖは、太陽電池の中央部ではＶ＝Ｖ0の一定値に設定され、端部では、太陽電池の端面側に向かってＶ0から徐々に低くなるように溶剤蒸散速度Ｖが設定される。 FIG. 6 is a diagram showing this state. The horizontal axis is the solar cell position along the longitudinal direction of the wiring material, and the vertical axis is the solvent evaporation rate V. As shown in FIG. 6, the solvent evaporation rate V is set to a constant value of V = V 0 at the center of the solar cell, and gradually decreases from V 0 toward the end face of the solar cell at the end. Thus, the solvent evaporation rate V is set.
　図７は、接続用電極２０，２３の端部を覆い、中央部を露出する治具３４を用いて、溶剤蒸散速度Ｖを接続用電極２０，２３の端部で低くする例を示す図である。白抜き矢印３５は、加熱雰囲気や換気雰囲気を示す。 FIG. 7 is a diagram showing an example in which the solvent evaporation rate V is lowered at the end portions of the connection electrodes 20 and 23 by using a jig 34 that covers the end portions of the connection electrodes 20 and 23 and exposes the central portion. is there. A white arrow 35 indicates a heating atmosphere or a ventilation atmosphere.
　治具３４は接続用電極２０，２３の中央部を覆っていないので、中央部は、加熱温度が高く、換気も十分となり、溶剤蒸散速度Ｖが高いＶ0となる。接続用電極２０，２３の端部は治具３４で覆われているので、加熱雰囲気からの加熱が妨げられ、加熱温度が低くなり、また、換気も適切な状態から比較して弱い状態であるので、溶剤蒸散速度Ｖは端面側に向かってＶ0よりも次第に小さな値となる。このようにして、太陽電池位置に応じた溶剤蒸散速度Ｖの制御を行うことができる。 Since the jig 34 does not cover a central portion of the connection electrode 20 and 23, the central portion has a high heating temperature, ventilation becomes sufficient, the solvent evaporation rate V high V 0. Since the ends of the connection electrodes 20 and 23 are covered with the jig 34, the heating from the heating atmosphere is hindered, the heating temperature is lowered, and the ventilation is weak compared to the appropriate state. since, the solvent evaporation rate V becomes gradually smaller than V 0 toward the end face side. In this way, the solvent evaporation rate V can be controlled in accordance with the solar cell position.
　融着率制御として、図１のＳ１４で説明した接続用電極の形成のための加熱速度ｄθを端部と中央部で異ならせる方法を用いることができる。加熱速度ｄθは、端部を中央部に比較して低い値にする。端部と中央部との間の加熱速度ｄθの変化は、中央部から端部に向かって連続的に低くなるようにすることがよい。連続的に低くする程度は、これによる融着率Ｍの低下を見ながら実験的に定めることがよい。実験結果によって、例えば、端部に向かって加熱速度ｄθを直線的に低下するようにしてもよく、曲線的に低下するようにしてもよい。 As the fusion rate control, a method in which the heating rate dθ for forming the connection electrode described in S14 of FIG. 1 is made different between the end portion and the center portion can be used. The heating rate dθ is set to a low value compared to the center portion at the end portion. It is preferable that the change in the heating rate dθ between the end portion and the center portion is continuously decreased from the center portion toward the end portion. The degree of continuous lowering is preferably determined experimentally while observing the decrease in the fusion rate M. Depending on the experimental result, for example, the heating rate dθ may be decreased linearly or curvedly toward the end.
　図８はその様子を示す図である。横軸は配線材の長手方向に沿った太陽電池位置で、縦軸は加熱速度ｄθである。図８に示されるように、加熱速度ｄθは、太陽電池の中央部ではｄθ＝ｄθ0の一定値に設定され、端部では、太陽電池の端面側に向かってｄθ0から徐々に低くなるように加熱速度ｄθが設定される。 FIG. 8 shows the state. The horizontal axis is the solar cell position along the longitudinal direction of the wiring material, and the vertical axis is the heating rate dθ. As shown in FIG. 8, the heating rate dθ is set to a constant value of dθ = dθ 0 at the center of the solar cell, and gradually decreases from dθ 0 toward the end face of the solar cell at the end. Is set to a heating rate dθ.
　融着率制御として、図１のＳ１１で説明したフレーク混合比ＦＲを端部と中央部で異ならせる方法を用いることができる。フレーク混合比ＦＲは、端部を中央部に比較して高い値にする。端部と中央部との間のフレーク混合比ＦＲの変化は、中央部から端部に向かって連続的に高くなるようにすることがよい。連続的に高くする程度は、これによる融着率Ｍの低下を見ながら実験的に定めることがよい。実験結果によって、例えば、端部に向かってフレーク混合比ＦＲを直線的に高くするようにしてもよく、曲線的に高くするようにしてもよい。 As the fusion rate control, a method in which the flake mixing ratio FR described in S11 of FIG. 1 is made different between the end portion and the center portion can be used. The flake mixing ratio FR is set to a high value as compared with the center portion. The change in the flake mixing ratio FR between the end portion and the center portion is preferably continuously increased from the center portion toward the end portion. The degree of continuous increase is preferably determined experimentally while observing the decrease in the fusion rate M. Depending on the experimental result, for example, the flake mixing ratio FR may be increased linearly toward the end or may be increased in a curved manner.
　図９はその様子を示す図である。横軸は配線材の長手方向に沿った太陽電池位置で、縦軸はフレーク混合比ＦＲである。図９に示されるように、フレーク混合比ＦＲは、太陽電池の中央部ではＦＲ＝ＦＲ0の一定値に設定され、端部では、太陽電池の端面側に向かってＦＲ0から徐々に高くなるようにフレーク混合比ＦＲが設定される。 FIG. 9 shows the state. The horizontal axis is the solar cell position along the longitudinal direction of the wiring material, and the vertical axis is the flake mixing ratio FR. As shown in FIG. 9, the flake mixing ratio FR is set to a constant value of FR = FR 0 at the center of the solar cell, and gradually increases from FR 0 toward the end face of the solar cell at the end. Thus, the flake mixing ratio FR is set.
　フレーク２２はネットワーク構造を分断する作用を有するので、融着によって生じる応力を緩和する働きを有する。フレーク混合比ＦＲが高いほど、導電率の向上が犠牲になるが、融着によって生じる応力をより緩和する。 Since the flakes 22 have an action of dividing the network structure, the flakes 22 have a function of relieving stress caused by fusion. The higher the flake mixing ratio FR, the higher the conductivity is sacrificed, but the stress caused by the fusion is more relaxed.
　図１０は、接続用電極２０，２３の長手方向に沿った太陽電池の断面図である。ここでは、フレーク混合比ＦＲの相違を、溶融凝集した接続用電極２０，２３の断面図におけるフレーク２２の単位面積当たりの数の相違で示した。端部の断面図におけるフレーク２２の単位面積当たりの数は、中央部の断面図におけるフレーク２２の単位面積当たりの数よりも多い。 FIG. 10 is a cross-sectional view of the solar cell along the longitudinal direction of the connection electrodes 20 and 23. Here, the difference in the flake mixing ratio FR is shown by the difference in the number per unit area of the flakes 22 in the cross-sectional views of the connection electrodes 20 and 23 which are melt-aggregated. The number per unit area of the flakes 22 in the end cross-sectional view is larger than the number per unit area of the flakes 22 in the central cross-sectional view.
　フレーク混合比ＦＲを太陽電池の端部と中央部で異ならせるには、導電ペーストとして、標準のフレーク混合比ＦＲを有する導電ペーストと、標準よりは高いフレーク混合比ＦＲを有する導電ペーストの少なくとも２種類を予め準備する。そして、中央部に標準のフレーク混合比ＦＲを有する導電ペーストを塗布し、端部に標準よりは高いフレーク混合比ＦＲを有する導電ペーストを塗布する。このようにして、太陽電池位置に応じたフレーク混合比ＦＲの制御を行うことができる。 In order to make the flake mixing ratio FR different between the end portion and the central portion of the solar cell, at least two conductive pastes having a standard flake mixing ratio FR and a conductive paste having a flake mixing ratio FR higher than the standard are used as the conductive paste. Prepare the type in advance. Then, a conductive paste having a standard flake mixing ratio FR is applied to the central portion, and a conductive paste having a flake mixing ratio FR higher than the standard is applied to the end portion. In this way, the flake mixture ratio FR can be controlled according to the solar cell position.
　１０　太陽電池、１１　光電変換部、１２，１３　透明導電膜、２０，２３　接続用電極、２１　球状粉、２２　フレーク、２４，２６　接着剤、２５，２７　配線材、３０　下ツール、３１　上ツール、３２，３３　加熱部、３４　治具。 10 solar cell, 11 photoelectric conversion part, 12, 13 transparent conductive film, 20, 23 connection electrode, 21 spherical powder, 22 flakes, 24, 26 adhesive, 25, 27 wiring material, 30 lower tool, 31 upper tool, 32, 33 heating unit, 34 jig.

Claims (10)

  1. 　導電性粒子を含むペースト材を用意し、
    　前記ペースト材を光電変換部の主面上に長手方向を有するように塗布し、
    　予め定めた所定温度で前記ペースト材を加熱して、前記長手方向に沿った前記光電変換部の端部における前記導電性粒子の融着率が、前記長手方向に沿った前記光電変換部の中央部における前記融着率よりも低くなるように前記導電性粒子を互いに融着させて接続用電極を形成する、太陽電池の製造方法。     Prepare a paste material containing conductive particles,
    Applying the paste material so as to have a longitudinal direction on the main surface of the photoelectric conversion part,
    The paste material is heated at a predetermined temperature determined in advance, and the fusion rate of the conductive particles at the end of the photoelectric conversion unit along the longitudinal direction is the center of the photoelectric conversion unit along the longitudinal direction. A method for manufacturing a solar cell, wherein the conductive particles are fused together to form a connection electrode so as to be lower than the fusion rate in the part.
  2. 　請求項１に記載の太陽電池の製造方法において、
    　前記接続用電極の平面的配置の部位によって前記ペースト材の加熱温度が異なる、太陽電池の製造方法。     In the manufacturing method of the solar cell of Claim 1,
    The manufacturing method of the solar cell in which the heating temperature of the said paste material changes with the site | parts of the planar arrangement | positioning of the said electrode for a connection.
  3. 　請求項１に記載の太陽電池の製造方法において、
    　前記電極の平面的配置の部位によって前記溶剤の蒸散速度が異なる、太陽電池の製造方法。     In the manufacturing method of the solar cell of Claim 1,
    The method for producing a solar cell, wherein the evaporation rate of the solvent varies depending on the planar arrangement of the electrodes.
  4. 　請求項１に記載の太陽電池の製造方法において、
    　前記電極の平面的配置の部位によって前記ペースト材の加熱速度が異なる、太陽電池の製造方法。     In the manufacturing method of the solar cell of Claim 1,
    The method for manufacturing a solar cell, wherein the heating rate of the paste material varies depending on the planar arrangement of the electrodes.
  5. 　請求項１に記載の太陽電池の製造方法において、
    　前記電極の平面的配置の部位によって前記塗布される前記ペースト材の前記フレーク混合比が異なる、太陽電池の製造方法。     In the manufacturing method of the solar cell of Claim 1,
    The method for manufacturing a solar cell, wherein the flake mixing ratio of the paste material to be applied is different depending on the planar arrangement of the electrodes.
  6. 　光電変換部と、
    　光電変換部の主面上に長手方向を有して配置された接続用電極と、
    　を備え、
    　前記接続用電極は、互いに融着してネットワーク構造を構成する導電性粒子を含み、
    　前記ネットワーク構造は、前記長手方向に沿った前記光電変換部の端部における前記導電性粒子の融着率が、前記長手方向に沿った前記光電変換部の中央部における前記導電性粒子の融着率よりも低くなるように構成されている、太陽電池。     A photoelectric conversion unit;
    A connection electrode disposed on the main surface of the photoelectric conversion portion with a longitudinal direction;
    With
    The connection electrode includes conductive particles that are fused together to form a network structure;
    In the network structure, the fusion rate of the conductive particles at the end of the photoelectric conversion unit along the longitudinal direction is such that the conductive particles are fused at the center of the photoelectric conversion unit along the longitudinal direction. The solar cell is configured to be lower than the rate.
  7. 　光電変換部と、
    　光電変換部の主面上に長手方向を有して配置された接続用電極と、
    　を備え、
    　前記接続用電極は、互いに融着してネットワーク構造を構成する導電性粒子を含み、
    　前記ネットワーク構造は、前記接続用電極の剥離試験において、長手方向に沿った前記光電変換部の端部において凝集剥離を生じさせ、前記長手方向に沿った前記光電変換部の中央部において界面剥離を生じさせるように構成されている、太陽電池。     A photoelectric conversion unit;
    A connection electrode disposed on the main surface of the photoelectric conversion portion with a longitudinal direction;
    With
    The connection electrode includes conductive particles that are fused together to form a network structure;
    In the peeling test of the connection electrode, the network structure causes cohesive peeling at an end portion of the photoelectric conversion unit along the longitudinal direction, and performs interface peeling at a central portion of the photoelectric conversion unit along the longitudinal direction. A solar cell that is configured to produce.
  8. 　請求項６または７に記載の太陽電池において、
    　前記接続用電極は樹脂を含む、太陽電池。     The solar cell according to claim 6 or 7,
    The solar cell, wherein the connection electrode includes a resin.
  9. 　請求項６から８のいずれか１に記載の太陽電池において、
    　前記導電性粒子は球状粉とフレークとを含み、
    　前記端部における前記球状粉に対する前記フレークの混合比は、前記中央部における前記混合比よりも大きい、太陽電池。     The solar cell according to any one of claims 6 to 8,
    The conductive particles include spherical powder and flakes,
    The solar cell in which the mixing ratio of the flakes to the spherical powder at the end is larger than the mixing ratio at the center.
  10. 　請求項６から９のいずれか１に記載の太陽電池において、
    　前記光電変換部の主面上に形成された透明導電膜をさらに備え、
    　前記接続用電極は、前記透明導電膜上に配置されている、太陽電池。     The solar cell according to any one of claims 6 to 9,
    A transparent conductive film formed on the main surface of the photoelectric conversion unit;
    The connection electrode is a solar cell disposed on the transparent conductive film.
PCT/JP2012/069387 2012-07-31 2012-07-31 Method for producing solar cell and solar cell WO2014020672A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008010857A (en) * 2006-05-30 2008-01-17 Kyocera Corp Solar cell module
WO2009090915A1 (en) * 2008-01-17 2009-07-23 Nichia Corporation Method for producing conductive material, conductive material obtained by the method, electronic device containing the conductive material, light-emitting device, and method for manufacturing light-emitting device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008010857A (en) * 2006-05-30 2008-01-17 Kyocera Corp Solar cell module
WO2009090915A1 (en) * 2008-01-17 2009-07-23 Nichia Corporation Method for producing conductive material, conductive material obtained by the method, electronic device containing the conductive material, light-emitting device, and method for manufacturing light-emitting device

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