JP5116363B2 - Manufacturing method of conductor wire - Google Patents

Description

The present invention relates for example such as a plurality of solar cell elements, in the manufacture how the conductor lines electrically connecting a plurality of electronic components

  2. Description of the Related Art Conventionally, solar cells that directly convert light energy into electric power using a semiconductor electromotive force effect are known. A solar cell is configured by connecting a plurality of panel-like solar cell elements. As a conductor wire connecting these solar cell elements, that is, as an inner lead wire, a copper wire surface is usually solder-coated. I am using it. That is, the solar cell element is electrically connected to the inner lead wire by soldering the solder coated on the inner lead wire with the flux and using the bus bar electrode made of silver (Ag) on the solar cell element. Connected to.

  However, the bonding temperature in such solder bonding is as high as about 240 ° C. when lead-free solder is used. Therefore, when solder bonding is applied to a solar cell, the solar cell element and the inner lead wire are caused by the difference in thermal shrinkage between the solar cell element made of silicon or the like and the inner lead wire made of copper wire. Stress is generated during this period. Therefore, in the solar cell, the stress causes warping or cracking of the solar cell element, leading to a failure or peeling of the bus bar electrode from the solar cell element.

  Therefore, in order to reduce such stress, a technique of using invar (Cu-36 mass% Ni) having a small thermal expansion coefficient instead of the copper wire constituting the inner lead wire has been proposed (for example, Patent Documents). 1 etc.). In addition to such a method of changing the material of the inner lead wire, contrivances such as reducing the stress by changing the shape of the connection or the like have been made (see, for example, Patent Document 2 and Patent Document 3). .) Furthermore, although not an inner lead wire, a solar cell in which a plurality of electrodes are electrically connected via an anisotropic conductive film has also been proposed (see, for example, Patent Document 4).

JP 2006-54355 A JP-A-2005-191200 JP 2005-302902 A JP-A-61-284773

  However, in the conventional technology using invar with a small thermal expansion coefficient, the volume resistivity of the invar is larger than that of the copper wire, and the resistance value of the inner lead wire itself is increased, thereby reducing the power generation efficiency of the solar cell. It is not practical to change the shape of the inner lead wire or the shape of the connection.

  Moreover, in the conventional technique which solder-joins a solar cell element and an inner lead wire, a flux is required to improve solder wettability. Therefore, in such a technique, it is necessary to clean the flux after joining, and there is a problem that this cleaning process is largely tacted, and if there is insufficient cleaning of the flux, the surface of the solar cell element Since the flux remains on top, there is also a problem that power generation efficiency is reduced.

  Such a problem is not limited to the inner lead wire that electrically connects a plurality of solar cell elements, but the stress due to thermal expansion generated between the conductor wire and the conductor wire due to a different thermal contraction rate. It exists in common with any of a plurality of electronic components that cause defects due to the above.

The present invention has been made in view of such circumstances, and manufacture of a conductor wire capable of extremely efficiently and easily manufacturing a conductor wire that can greatly reduce the occurrence of defects in electronic components to be connected. an object of the present invention is to provide an mETHODS.

  The inventor of the present application has conducted extensive research on the bonding of conductor wires, and as a result, has found a new material to replace solder as the bonding material, and has completed the present invention.

That is, the method for manufacturing a conductor wire according to the present invention that achieves the above-described object is a method for manufacturing a conductor wire for electrically connecting a plurality of electronic components, wherein the conductor has a different thermal contraction rate from the electronic component. A state in which the adhesive is applied only to the surface side from one end of a predetermined metal wire as a main material of the wire over a predetermined length, and the adhesive is applied only to the back surface from the other end of the metal wire over a predetermined length and so that, with a coating step of applying the adhesive to the main material, and a film step of a film by dry or B stage the adhesive agent applied in the coating step, the coating step Using a first coater, a width of a predetermined length less than a half length in the short direction of the metal foil from one edge of the metal foil on the back surface of the long metal foil as the main material In the longitudinal direction of the metal foil Using the second coater, the step of applying the liquid adhesive, the step of reversing the front and back surfaces of the metal foil coated with the adhesive only on the back surface using a predetermined roller, and the second coater In the surface of the metal foil with the front and back surfaces reversed, the liquid foil extends in the longitudinal direction of the metal foil with a predetermined length less than half the length of the metal foil from the other edge of the metal foil. And a step of applying the adhesive .

  In such a method of manufacturing a conductor wire according to the present invention, a conductor wire that can be joined to an electronic component via an adhesive is not formed by a long metal foil line process, rather than a conventional solder joint. It can be manufactured very efficiently and easily.

  According to the present invention, it is possible to greatly reduce the occurrence of defects in electronic components, and in particular, by using them as inner lead wires for joining with solar cell elements as electronic components, the power generation efficiency of solar cells can be reduced. It can be avoided. Further, according to the present invention, such a conductor wire can be manufactured very efficiently and easily.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  This embodiment is a solar cell that directly converts light energy into electric power using the electromotive force effect of a semiconductor. In particular, this solar cell is obtained by joining a plurality of panel-like solar cell elements and inner lead wires as conductor wires that electrically connect these solar cell elements by a method other than conventional solder bonding. .

  For example, as shown in a cross-sectional view in FIG. 1, a solar cell is composed of an ethylene / vinyl acetate copolymer between a transparent tempered glass 12 supported by a predetermined aluminum frame 11 and a weather resistant film 13. A transparent resin 14 such as a combination (Ethylene-Vinyl Acetate; EVA) is embedded, and a plurality of solar cell elements 20 are arranged in the transparent resin 14 according to a predetermined rule.

  The solar cell element 20 is schematically shown in a sectional view in FIG. 2 and, as shown in a perspective view in FIG. 3, on a surface of a semiconductor substrate 21 such as silicon for collecting current made of silver (Ag). The finger electrodes 22 and the output bus bar electrodes 23 are formed to be orthogonal to each other in the same layer. In addition, in the same figure, although the cross section of the surface side of the solar cell element 20 is shown, although it does not illustrate in particular on the back surface side of the solar cell element 20, the predetermined electrode is formed.

  Further, on the front and back surfaces of such a solar cell element 20, inner lead wires whose main material is a metal wire such as a copper wire having a thermal contraction rate different from that of the solar cell element 20 along the bus bar electrode 23. 40 is bonded via a predetermined adhesive 30.

  Here, as the adhesive 30, it is desirable to use an anisotropic conductive adhesive film (ACF). An anisotropic conductive adhesive film is made of a material in which fine conductive particles are dispersed in a film-like insulating resin material. By applying pressure and heating, the thickness of the conductive conductive adhesive film is increased through the conductive particles. It has an electrical connection function in the direction and an insulation function in the direction perpendicular to the thickness direction. Specifically, the anisotropic conductive adhesive film is preferably a cured epoxy adhesive containing 30% by weight or less of conductive particles, and has a Young's modulus after curing of about 0.1 GPa to 30 GPa. Is desirable. In the case where conductivity is not required, the adhesive 30 may be a non-conductive film (NCF) or a conductive paste using a curable resin as a binder.

  As shown in FIG. 1 and FIG. 2, the solar cell element 20 is configured such that one end of the inner lead wire 40 is wired over substantially the entire length of the bus bar electrode 23 on the surface side via the adhesive 30. Is electrically connected to the inner lead wire 40. The other end of the inner lead wire 40 is electrically connected to the electrode on the back surface side of the adjacent solar cell element 20 through the adhesive 30. That is, the solar cell element 20 is electrically connected to the adjacent solar cell element 20 by joining to the inner lead wire 40 via the bus bar electrode 23. In addition, as the inner lead wire 40, in order to improve the weather resistance, it is desirable not to use a single metal wire but to subject the metal wire surface to rust prevention treatment such as tin plating or pre-coating. Further, in the solar cell, the adhesive 30 and the inner lead wire 40 may be provided as the inner lead wire 40 in which the adhesive 30 is applied to the surface of the metal wire, instead of being provided as separate units. Specifically, in a solar cell, an inner conductive wire 40 with an anisotropic conductive adhesive film is used by applying an anisotropic conductive adhesive film to a copper foil and cutting it into a slit shape. In this case, steps such as temporary sticking of the anisotropic conductive adhesive film on the solar cell element 20 can be omitted. A method for manufacturing such an inner lead wire with an adhesive will be described in detail later.

  In manufacturing a solar cell including such a solar cell element 20, for example, as shown in FIG. 4A, when the solar cell element 20 is prepared, as shown in FIG. 4B, an adhesive is prepared. The inner lead wire 40 is connected to the solar cell element 20 through 30. 4 (c), a plurality of such solar cell elements 20 are arranged and adjacent solar cell elements 20 are electrically connected to each other in FIG. 4 (d) and FIG. As shown in the middle (e), the weather resistant film 13, the transparent resin film that becomes the transparent resin 14, the solar cell element 20, the transparent resin film that becomes the transparent resin 14, and the transparent tempered glass 12 are arranged in this order from the bottom. A solar cell is manufactured by laminating and laminating by hot pressing and attaching a predetermined frame terminal.

  Thus, in the solar cell, the solar cell element 20 and the inner lead wire 40 are joined via the adhesive 30 made of an anisotropic conductive adhesive film or the like instead of the conventional solder joint. Therefore, in the solar cell, the solar cell element 20 and the inner lead wire 40 can be bonded at a lower temperature than the conventional solder bonding, such as about 180 ° C. at which the resin of the adhesive 30 is cured. Stress due to expansion can be reduced, and the occurrence of defects such as warpage and cracking of the solar cell element 20 and peeling of the bus bar electrode 23 can be greatly reduced. Also, the adhesive 30 itself is effective in stress relaxation because it has a Young's modulus smaller than that of solder. And in the solar cell, since it is not necessary to change the shape of the inner lead wire 40 and the shape of the connection, it is possible to avoid a decrease in power generation efficiency, and because flux is not required like solder bonding, Manufacturing with a high yield can be realized without worrying about extra cleaning steps and worrying about a decrease in power generation efficiency due to insufficient cleaning.

  The present inventor made a sample simulating the solar cell element 20 and observed its state in order to confirm the effect of using such an adhesive 30.

  Specifically, as shown in FIG. 5, a sample in which a firing type silver paste 52 was applied on the surface of a glass substrate 51 and a tab wire 53 simulating the inner lead wire 40 was provided thereon was produced. As the glass substrate 51 to which the silver paste 52 is applied, a glass substrate 51 having a size of 15 mm wide × 80 mm long × 0.7 mm thick and having a linear expansion coefficient close to that of silicon is used. As the tab wire 53, a copper wire having a width of 2 mm and a thickness of 0.15 mm and Sn-Ag-Cu lead-free solder having a dip plating thickness of 40 μm on one side was used. And this tab wire 53 was joined on the surface of the glass substrate 51 which apply | coated the silver paste 52 using the anisotropic conductive adhesive film "CP5832KS" by a Sony chemical & information device company. The joining conditions at this time are heating and pressurization for 15 seconds at a temperature of 180 ° C. and a pressure of 2 MPa. The anisotropic conductive adhesive film “CP5832KS” is obtained by blending approximately 13% by weight of conductive particles with an epoxy adhesive, and the Young's modulus after curing is approximately 2 GPa.

  Further, as a sample for comparison, a glass substrate 51 and a tab wire 53 coated with the silver paste 52 having the above-described specifications are used, and the tab wire 53 is made of silver using a flux “Delta Flux” manufactured by Senju Metal Industry Co., Ltd. A solder bonded product was produced on the surface of the glass substrate 51 to which the paste 52 was applied. The bonding conditions at this time are heating and pressurization for 15 seconds at a temperature of 240 ° C. and a pressure of 2 MPa.

  The appearance of a total of 4 samples of 2 types × 2 produced in this way was observed to confirm whether or not defects such as cracks occurred. The results are shown in FIGS. 6 (A) and 6 (B).

  When the back surface appearance of the sample was observed, as shown in the area surrounded by the square in FIG. 6A, three tab lines out of the four tab lines were joined. As a result, the glass substrate was not cracked at all, but the sample by bonding using the anisotropic conductive adhesive film shown in FIG. 6B did not crack at all.

  As is clear from this result, it can be said that the use of the adhesive 30 such as an anisotropic conductive adhesive film for the solar cell is very effective in reducing the occurrence of defects in the solar cell element 20.

  In the solar cell, as described above, the adhesive 30 and the inner lead wire 40 are not provided as separate single pieces, but are provided as the inner lead wire 40 in which the adhesive 30 is applied to the surface of the metal wire. Also good.

  Here, in the solar cell, as described above, one end of one inner lead wire 40 is joined to the bus bar electrode 23 on the surface side of the solar cell element 20, and the other end is the back surface of the adjacent solar cell element 20. It is necessary to join to the side electrode. Therefore, as the inner lead wire 40 in which the adhesive 30 is applied to the surface of the metal wire, for example, as shown in a sectional view in FIG. At the same time, it is necessary to manufacture a material in which the adhesive 30 is applied only on the back surface side over a predetermined length from the other end.

  As such an inner lead wire 40, the adhesive 30 is applied only to one surface of the metal foil which is the main material of the inner lead wire 40, and the adhesive 30 is dried or B-staged (semi-cured) to form a film. As shown in the upper part of FIG. 8 (a) and the upper part of FIG. 8 (b), the formed metal foil is bent at a substantially central portion in the longitudinal direction so that a metal wire 60 formed in a substantially Z shape is obtained. In addition, the metal wire 60 is cut using a predetermined cutting device such as a so-called Thomson blade type (Bik blade type), and further, as shown in the lower stage of FIG. 8A and the lower stage of FIG. The metal wire 60 is bent in a region from one end to the bent portion so that the one end is joined to the bus bar electrode 23 on the surface side of the solar cell element 20 and the other end On the back side of the adjacent solar cell element 20 It includes those formed so that it can be joined to the pole.

  Also, as shown in FIG. 9, the inner lead wire 40 is coated with an adhesive 30 only on one side of a metal foil, dried or B-staged into a film, and slitted with a predetermined width using a predetermined cutting device. The ends of the two metal wires 60 that are formed by cutting in a shape are not coated with the adhesive 30 by using a predetermined bonding agent 70, and one end of the solar cell element 20 is bonded to the end of the solar cell element 20. What was formed so that it might join to the electrode of the back surface side of the adjacent solar cell element 20 while joining to the bus bar electrode 23 of the surface side is mentioned.

  Further, as the inner lead wire 40, although not particularly illustrated, the adhesive 30 is applied to only one side of the metal foil, dried or B-staged to form a film, and formed into a slit with a predetermined width using a predetermined cutting device. When the metal wire 60 formed by cutting is twisted at a substantially central portion in the longitudinal direction at the time of joining to the solar cell element 20, one end thereof is joined to the bus bar electrode 23 on the surface side of the solar cell element 20, What formed so that the other end can be joined to the electrode of the back surface side of the adjacent solar cell element 20 is mentioned.

  Furthermore, the inner lead wire 40 can also be efficiently and easily manufactured by the following method.

  Specifically, as shown in FIG. 10, an elongated copper foil 100 is prepared as a main material of the inner lead wire 40, and the inner lead wire 40 is manufactured by line processing the copper foil 100. The length of the copper foil 100 in the short direction is the length of one inner lead wire 40 connecting two solar cell elements 20 arranged at a predetermined interval in order to constitute a solar cell. Identical.

  First, in manufacturing the inner lead wire 40, when the copper foil 100 is set on the production line so that the back surface is upward, the liquid adhesive 30 is applied to the back surface of the copper foil 100 using a predetermined coater 101. Apply. Here, the coater 101 has the copper foil 100 so that the application region of the adhesive 30 has a predetermined length less than a half length in the short direction of the copper foil 100 from one edge of the copper foil 100. It is provided in the vicinity of one end edge. Therefore, the adhesive 30 is applied over the longitudinal direction of the copper foil 100 with a predetermined length less than a half length of the copper foil 100 in the short direction from one edge of the copper foil 100.

  Thus, the copper foil 100 with the adhesive 30 applied only to the back surface is reversed by the two rollers 102 and 103 so that the front surface is upward. Here, the length of the rotating shaft direction which the copper foil 100 contacts is the copper foil so that the applied adhesive 30 may not peel off from the copper foil 100 by adhering to the rollers 102 and 103. The length of the copper foil 100 is approximately half the length in the short direction of 100, and is provided in the vicinity of the other edge opposite to one edge of the copper foil 100 close to the application region of the adhesive 30.

  And the liquid adhesive 30 is apply | coated to the surface of the copper foil 100 by which the front and back were reversed using the predetermined coater 104. FIG. This coater 104 also has the other side of the copper foil 100 so that the application region of the adhesive 30 has a predetermined length less than half the length of the copper foil 100 in the short direction from the other edge of the copper foil 100. It is provided in the vicinity of the edge. Therefore, the adhesive 30 is applied over the longitudinal direction of the copper foil 100 with a predetermined length less than a half length of the copper foil 100 in the short direction from the other edge of the copper foil 100.

  The copper foil 100 thus coated with the adhesive 30 on both the front and back sides is supplied to the film forming apparatus 105 in order to dry or form the liquid adhesive 30 into a B-stage. Specifically, as the film forming apparatus 105, when the resin of the adhesive 30 is a thermosetting resin, the adhesive 30 applied to the supplied copper foil 100 is heated to a predetermined temperature and dried. When a drying device such as an oven is used and the resin is a photocurable resin, a light irradiation device such as a laser device that irradiates ultraviolet light or the like to the adhesive 30 applied to the supplied copper foil 100 is used. It is done.

  And when the copper foil 100 passes through the film forming apparatus 105 and the liquid adhesive 30 is formed into a film, it uses a cutting device (not shown) such as a cutter to form a slit with a predetermined width along the short direction. Is cut off. Thereby, as previously shown in FIG. 7, the inner lead wire 40 in which the adhesive 30 is applied to the front and back surfaces of the copper wire can be manufactured.

  Thus, by carrying out line processing of the long copper foil 100, the inner lead wire 40 coated with the adhesive 30 can be manufactured very efficiently and easily. Such a manufacturing method is extremely effective as a method for mass-producing the inner lead wires 40 of uniform quality. Moreover, in this manufacturing method, the copper foil 100 in which the adhesive 30 is formed into a film is wound and stored using a reel, and the cutting process for forming the inner lead wire 40 is a subsequent process. Therefore, it is easy to store, and only the necessary number has to be cut according to the order, so that the yield can be improved.

  The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, an example in which the present invention is mainly applied to a silicon-based solar cell has been described. However, the present invention is applicable as long as adjacent solar cell elements are connected to each other via a conductor wire. Can do. Therefore, the present invention is not limited to any silicon solar cell including single crystal silicon type, polycrystalline silicon type, microcrystalline silicon type, amorphous silicon type, and other semiconductors such as GaAs type and calcobylite type. The present invention can also be applied to compound-based solar cells and dye-based solar cells such as dye-sensitized solar cells. Further, the present invention is not limited to forms such as a thin film type and a multi-junction type.

  Further, in the above-described embodiment, the solar cell in which the solar cell element and the inner lead wire are joined via the bus bar electrode has been described. However, the present invention is a type that does not have a bus bar electrode that can reduce cost, for example. Even solar cells that are electrically connected to adjacent solar cell elements by joining solar cell elements and inner lead wires through finger electrodes that have a narrower electrode width than bus bar electrodes can do. In this case, as the adhesive, any adhesive that can be electrically bonded to a semiconductor substrate or the like may be used, and an anisotropic conductive adhesive film or other conductive adhesive may be used. In a solar cell in which the solar cell element and the inner lead wire are joined via such a finger electrode, the electrode electrode of the finger electrode is narrow, so that the solder joint cannot have the required strength. It is extremely effective to use a conductive adhesive as in the present invention.

  Further, in the above-described embodiment, the inner lead wire for electrically connecting a plurality of solar cell elements has been described. However, the present invention is different from the conductor wire in that the thermal contraction rate is different from the conductor wire. The present invention can be easily applied even when a plurality of arbitrary electronic components that cause defects due to the stress caused by thermal expansion are electrically connected.

  Furthermore, in the above-described embodiment, the manufacturing method for processing a long copper foil has been described. However, the present invention is not limited to the main material of the conductor wire, and other metal foils are lined. Even when processing, it can be applied.

  Thus, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

It is a sectional side view explaining the structure of the solar cell shown as embodiment of this invention. It is a sectional side view explaining the structure of the solar cell element with which the solar cell shown as embodiment of this invention is provided. It is a perspective view explaining the structure of the solar cell element with which the solar cell shown as embodiment of this invention is provided. It is a figure for demonstrating the manufacturing method of the solar cell shown as embodiment of this invention. It is a perspective view explaining the structure of the sample which simulated the solar cell element. It is the figure which photographed the sample by solder joining. It is the figure which copied the sample by joining using an anisotropic conductive adhesive film. It is a sectional side view explaining the structure of the inner lead wire with which the solar cell shown as embodiment of this invention is provided. It is a top view explaining the specific example of the inner lead wire which apply | coated the adhesive agent. FIG. 9 is a perspective view of the inner lead wire shown in FIG. It is a sectional side view explaining the other specific example of the inner lead wire which apply | coated the adhesive agent. It is a figure for demonstrating the manufacturing method of the inner lead wire which apply | coated the adhesive agent, and is a figure explaining the structure of a manufacturing line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Aluminum frame 12 Transparent tempered glass 13 Weather resistant film 14 Transparent resin 20 Solar cell element 21 Semiconductor substrate 22 Finger electrode 23 Busbar electrode 30 Adhesive 40 Inner lead wire 51 Glass substrate 52 Silver paste 53 Tab wire 60 Metal wire 70 Bonding agent 100 Copper foil 101, 104 Coater 102, 103 Roller 105 Filming device

Claims (10)

A method of manufacturing a conductor wire for electrically connecting a plurality of electronic components,
The adhesive is applied only on the surface side from one end of a predetermined metal wire, which is the main material of the conductor wire, which has a different heat shrinkage rate from the electronic component, and from the other end of the metal wire to a predetermined length. An application step of applying the adhesive to the main material so that the adhesive is applied only on the back side;
A film forming step of forming a film by drying or B-stage the adhesive applied in the application step,
The application process
Using the first coater, on the back surface of the long metal foil as the main material, the width of a predetermined length less than half the length of the metal foil from one edge of the metal foil, Applying the liquid adhesive across the longitudinal direction of the metal foil;
Using a predetermined roller, reversing the front and back surfaces of the metal foil in which the adhesive is applied only to the back surface;
Using the second coater, on the surface of the metal foil whose front and back surfaces are reversed, the metal with a predetermined width less than half the length of the metal foil from the other edge of the metal foil. And a step of applying the liquid adhesive in the longitudinal direction of the foil. A step of cutting the metal foil formed by the adhesive in the film forming step using a predetermined cutting device along a short direction in a slit shape with a predetermined width to form the conductor wire; The method of manufacturing a conductor wire according to claim 1, comprising: The roller has a length in the rotation axis direction that the metal foil is in contact with, which is substantially half the length in the short direction of the metal foil, and one of the metal foils close to the application area of the adhesive. The method for manufacturing a conductor wire according to claim 1, wherein the conductor wire is provided in the vicinity of the other end edge opposite to the end edge. The method for producing a conductor wire according to claim 1, wherein in the film forming step, the adhesive is dried or B-staged to form a film using a predetermined film forming apparatus. When the resin of the adhesive is a thermosetting resin, the film forming apparatus is a drying apparatus that heats the adhesive to a predetermined temperature and dries, and when the resin is a photocurable resin Is a light irradiation device for irradiating the adhesive with light. The method for producing a conductor wire according to claim 4. Use a conductive adhesive as the adhesive.
  The method for producing a conductor wire according to claim 1. Use an anisotropic conductive adhesive film as the conductive adhesive.
  The method for producing a conductor wire according to claim 6. The anisotropic conductive adhesive film is obtained by curing an epoxy adhesive containing 30% by weight or less of conductive particles and having a Young's modulus after curing of 0.1 GPa to 30 GPa.
  The method for producing a conductor wire according to claim 7. Use a metal wire whose surface is rust-proofed
  The method for manufacturing a conductor wire according to any one of claims 1 to 8, wherein The plurality of electronic components are a plurality of solar cell elements arranged according to a predetermined rule,
  The conductor wire is an inner lead wire that electrically connects the plurality of solar cell elements.
  The method for manufacturing a conductor wire according to claim 1, wherein: