JP2009283606A - Connection structure of wiring member, and connection method of wiring member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection structure of a wiring member capable of improving the yield of a wiring member connection body by suppressing occurrence of warpage; and a connection method of wiring members. <P>SOLUTION: This connection structure of a wiring member is composed by connecting the wiring members to both a light reception surface and a back electrode of a solar cell through conductive connection materials. In relation to the connection structure of a wiring member using the conductive connection material where the elastic modulus on the light reception side is larger than that on the back electrode side, and this connection method of a wiring member for connecting the wiring members to both the light reception surface and the back electrode of the solar cell through the conductive connection materials, the connection method of a wiring member is characterized in that the conductive connection material where the elastic modulus on the light reception side is larger than that on the back electrode side is arranged on the surface of the solar cell with electrodes formed thereon, and tentatively subjected to press-bonding, and thereafter the wiring member is mounted on the conductive connection material, and then subjected to thermo compression bonding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wiring member connection structure and a wiring member connection method in which warpage generated when a wiring member is connected to a solar battery cell is reduced.

  FIG. 1 shows a wiring member connection structure in which solar cells 1 and a wiring member 3 are connected via a conductive connecting material 2. Conventionally, solder has been used as the conductive connecting material 2. Solder is widely used because it is excellent in connection reliability such as conductivity and fixing strength, is inexpensive and versatile (see, for example, Patent Documents 1 and 2).

  Moreover, as a wiring connection method that does not use solder, a connection method using a conductive adhesive or a connection method using a conductive film is known (see, for example, Patent Documents 3 to 6).

  In the conventional method, a wiring material is connected to both the light receiving surface and the back electrode through solder, a conductive film, or a conductive paste. When such a connection is made, the warpage is greater than before the connection. This warpage causes cracking of the solar battery cells in the subsequent manufacturing process of the solar battery module and causes a decrease in yield.

JP 2004-204256 A JP-A-2005-050780 JP 2000-286436 A JP 2001-357897 A Japanese Patent No. 3448924 JP 2005-101519 A JP 2007-214533 A

  An object of the present invention is to provide a wiring member connection structure and a wiring member connection method capable of suppressing the occurrence of warpage and improving the yield of the wiring member connection body.

  The present invention provides a wiring member connection structure in which a wiring member is connected to both a light receiving surface and a back electrode of a solar battery cell via a conductive connecting material, and is more elastic on the light receiving surface side than the back electrode side. The present invention relates to a connection structure for a wiring member using a conductive connection material having a high rate.

  The present invention also relates to the connection structure for a wiring member as described above, wherein the conductive connection material is a conductive film or a conductive paste in which conductive particles are dispersed and contained in a solder or insulating resin layer to impart conductive characteristics.

  In addition, the present invention provides a method for connecting a wiring member that connects a wiring member to both the light receiving surface and the back electrode of the solar battery cell via a conductive connection material. A wiring characterized in that a conductive connecting material having a higher elastic modulus than that of the back electrode side is disposed on the light receiving surface side, a wiring member is placed on the conductive connecting material after provisional pressure bonding, and then thermocompression bonding is performed. The present invention relates to a method for connecting members.

  Furthermore, the present invention provides the conductive film or conductive material in which the conductive connecting material used for electrical connection between the solar battery cell and the wiring member has conductive properties dispersed and contained in a solder or insulating resin layer. It is related with the connection method of said wiring member which is a paste.

  ADVANTAGE OF THE INVENTION According to this invention, the connection structure of a wiring member which can suppress the curvature of a wiring member connection body sufficiently efficiently, and the connection method of a wiring member can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. For the convenience of the drawings, the dimensional ratios in the drawings do not necessarily match those described.

  FIG. 2: is a schematic sectional drawing which shows an example of the process of the connection structure of the wiring member which becomes this invention. A method for mounting the flat wiring member 3 on the solar battery cell 1 using the thermocompression bonding apparatus 10 shown in FIG. 2 will be described. In the wiring member mounting method in the present invention, the wiring member 3 is thermocompression bonded to the solar battery cell 1 by the crimping head 5 and the heating stage 4.

  First, as shown in FIG. 2A, the solar battery cell 1 is placed on the stage 4 of the thermocompression bonding apparatus 10. And the conductive connection material 2 is arrange | positioned on the surface in which the electrode 1a of the photovoltaic cell 1 is formed, the crimping | compression-bonding head 5 is dropped, and the conductive connection material 2 is temporarily crimped | bonded to the photovoltaic cell 1. FIG.

  The pressure at this time is not particularly limited as long as it does not damage the wiring member, but is generally preferably 0.1 to 30.0 MPa. Moreover, you may pressurize, heating, and let heating temperature be the temperature which the electroconductive connection material 2 does not harden | cure substantially. These heating and pressurization are preferably performed in the range of 0.5 to 120 seconds.

  Next, as shown in FIG. 2B, after placing the wiring member 3 on the conductive connecting material 2, the pressure-bonding head 5 is lowered, and the heat is applied by the heat of the pressure-bonding head 5 (thermo-compression process). The connecting material 2 is cured ((c) in FIG. 2).

The pressing force by the pressure-bonding head 5 is not particularly limited as long as the wiring member 3 and the solar battery cell 1 are not damaged, but it is generally preferable that the pressure is 0.1 to 30.0 MPa.
The heating temperature by the pressure bonding head 5 and the heating stage 4 is a temperature at which the conductive connecting material 2 can be cured.

  The heating temperature is preferably 60 to 350 ° C, more preferably 70 to 300 ° C, and further preferably 80 to 260 ° C. If the heating temperature is less than 60 ° C, the curing rate tends to be slow, and if it exceeds 350 ° C, unwanted side reactions tend to proceed. The heating time is preferably from 0.1 to 180 seconds, more preferably from 0.5 to 180 seconds, and further preferably from 1 to 180 seconds.

  The heating of the conductive connecting material 2 in the thermocompression bonding step is not limited to heating by heating from both surfaces of the pressure bonding head 5 and the heating stage 4. For example, the heating may be performed only from either the pressure-bonding head 5 or the heating stage 4.

  By curing the conductive connection material 2 in the thermocompression bonding step, a wiring member connection structure in which the wiring member 3 is mounted on the solar battery cell 1 is obtained. FIG. 3 is a schematic cross-sectional view showing an enlarged connection portion of the wiring member connection structure 50. The connection part of the wiring member connection structure 50 includes a cured product 2A of the adhesive component 2a contained in the conductive connection material 2 and conductive particles 2b dispersed therein.

  In the wiring member connection structure 50, the electrode 1a of the opposing solar battery cell 1 and the wiring member 3 are electrically connected via the conductive particles 2b. That is, the conductive particles 2 b are in direct contact with both the electrode 1 a and the wiring member 3.

  For this reason, the connection resistance between the electrodes 1a and 3 is sufficiently reduced, and a good electrical connection between the electrode 1a and the wiring member 3 becomes possible. Therefore, the flow of current between the electrode 1a and the wiring member 3 can be made smooth, and the function of the wiring member can be fully exhibited.

(Conductive connection material)
The adhesive film 15 shown in FIG. 4 includes a tape-like substrate 6 and the conductive connection material 2 provided on one surface thereof. The conductive connecting material 2 is obtained by molding an adhesive composition containing an adhesive component 2a containing a thermosetting resin and conductive particles 2b dispersed in the adhesive component 2a into a film shape. When the conductive connecting material 2 is used, the tape-like base material 6 is peeled off.

  Examples of the thermosetting resin contained in the adhesive component 2a of the conductive connecting material 2 include acrylic resin, methacrylic resin, urethane resin, unsaturated polyester resin, epoxy resin, and phenol resin.

  The form of the curing reaction of the thermosetting resin is not particularly limited, and any polymerization form such as double bond radical polymerization, ionic polymerization, and polyaddition may be used.

The adhesive component 2a may include components other than the thermosetting resin. Examples of such components include a film-forming polymer, a radical polymerization initiator, an epoxy curing agent, a silane coupling agent, a catalyst, and a filler.
The glass transition temperature Tg of the cured product of the thermosetting connection material can be controlled by appropriately adjusting the type or blending amount of the thermosetting resin, the film-forming polymer, and other components.

  Examples of the conductive particles 2b included in the conductive connection material 2 include metal particles such as Au, Ag, Pt, Ni, Cu, W, Sb, Sn, and solder, and carbon particles. Coated particles in which conductive glass, ceramic, plastic, or the like is used as a core and the core is coated with the above metal or carbon may be used.

  The average particle diameter of the conductive particles is preferably 1 to 18 μm from the viewpoints of dispersibility and conductivity. Insulating coating particles obtained by coating conductive particles with an insulating layer may be used.

  The blending ratio of the conductive particles 2b is preferably 0.01 to 30 parts by volume and more preferably 0.1 to 10 parts by volume with respect to 100 parts by volume of the adhesive component of the conductive connection material 2. . If the blending ratio is less than 0.01 part by volume, the connection resistance between the opposing electrodes tends to increase, and if it exceeds 30 parts by volume, a short circuit between adjacent electrodes tends to occur.

What is necessary is just to select the thickness of the electroconductive connection material 2 according to the adhesive agent component to be used, the kind of to-be-adhered object, etc., but it is preferable that it is 5-100 micrometers.
Moreover, what is necessary is just to adjust the width | variety of the electroconductive connection material 2 according to a use application, but generally it is about 0.5-5 mm.

  The substrate 6 of the adhesive film 15 has a tape shape. The substrate 6 has a length of about 1 to 300 mm, a thickness of about 4 to 200 μm, and a width of about 0.5 to 30 mm. The length, thickness, and width of the substrate 6 are not limited to the above ranges. However, from the viewpoint of improving the power generation efficiency of the solar cell, the width of the conductive connection material 2 is preferably the same as the width of the wiring member 3, and the width of the base member 6 is the width of the conductive connection material 2 provided thereon. It is preferable that the width is wider.

  The substrate 6 is, for example, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, ethylene / vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, Various tapes made of synthetic rubber or liquid crystal polymer can be used. However, the material constituting the base material 6 is not limited to these, and as the base material 6, a material having a release treatment applied to the contact surface with the conductive connecting material 2 may be used. .

As the conductive connection material 2, various commercially available conductive films (CF), conductive pastes (CP), non-conductive films (NCF), and the like may be used.
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

  For example, in the above embodiment, the case where the conductive connection material 2 having a single layer structure is used is exemplified, but a conductive connection material having a multilayer structure may be used. The conductive connection material having a multilayer structure can be produced by laminating a plurality of layers having different types of adhesive components and conductive particles or different contents thereof on the substrate 6.

  The adhesive film 15 shown in FIG. 5 includes a base material 6 and a conductive connection material 18 having a two-layer structure formed on one surface thereof. The conductive connecting material 18 includes a conductive particle non-containing layer 18a containing no conductive particles and a conductive particle containing layer 18b containing conductive particles. In addition, as the adhesive component of the conductive particle non-containing layer 18a and the conductive particle-containing layer 18b, the same adhesive component as the adhesive component 2a of the circuit connecting material 2 described above can be used.

  Furthermore, the wiring member mounted on the solar battery cell 1 is not limited to the wiring member. For example, the conductive connecting material according to the present invention may be mounted on a wiring board such as a glass fiber reinforced organic substrate such as a glass fiber reinforced epoxy substrate or a paper phenol substrate, a ceramic substrate, a laminate, or a polyimide film.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited to a following example.
Example 1
An apparatus having the same configuration as the thermocompression bonding apparatus shown in FIG. 2 was used, and the wiring member was mounted on the solar battery cell as described below to produce a wiring member connection structure.

  First, wiring member (square copper ribbon wire, 150 mm × 2 mm, thickness 0.16 mm), solar cell (polycrystalline silicon, 125 mm × 125 mm, thickness 0.2 mm), conductive as a thermosetting conductive connection material A film was prepared.

  A solar battery cell was placed on the stage of a thermocompression bonding apparatus, and a conductive film was temporarily pressure-bonded thereon. Next, a wiring member was mounted on the conductive film, and then the crimping head was lowered from above to perform thermocompression bonding.

  The wiring member was pressed at 2 MPa by the contact surface of the pressure-bonding head, and heated by the heat of the pressure-bonding head and the heating stage so that the temperature of the conductive film reached 170 ° C. in 15 seconds to obtain a circuit connection body.

  The elastic modulus at room temperature (25 ° C.) of the conductive film 1 used in this example was 3.5 GPa, and the elastic modulus at room temperature (25 ° C.) of the conductive film 2 was 1.1 GPa. The elastic modulus is determined by placing the conductive film in an oven at 180 ° C. for 1 hour and completely curing it, and then using a dynamic viscoelasticity measuring device DMS6100 (manufactured by SII) with a heating rate of 5 ° C./min and a frequency of 10 Hz. , Measured under conditions of amplitude 5 μm and tensile mode.

<Measurement of solar cell warpage>
The warpage of the solar battery cell produced as described above was measured as follows. First, the solar cell was placed on the movable stage of a non-contact displacement meter with the back surface facing up, and the displacement in the height direction was measured at 10 mm intervals in the XY directions with respect to the center of the cell.

  Next, an average surface is calculated from the measurement results using a two-dimensional least-squares method, and an average value of residuals from the average surface of the four corners of the measurement results and a minimum value obtained by subtracting the measurement results from the average surface are calculated. The difference was defined as warpage. The difference between the warp before and after the connection of the wiring member was defined as the warp after the connection.

  Table 1 shows the physical properties of the conductive films used in Example 1 and Comparative Examples 1 and 2.

  Table 2 shows the evaluation results (Example 1 and Comparative Examples 1 and 2) of the wiring member connection structure produced above.

It is a schematic sectional drawing which shows an example of the connection structure of the wiring member which becomes this invention. It is a schematic sectional drawing which shows an example of the process of the connection structure of the wiring member which becomes this invention. It is a schematic cross section which expands and shows the connection part of the connection structure of a wiring member. It is sectional drawing which shows an example of an electroconductive connection material. It is sectional drawing which shows another example of an electroconductive connection material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar cell 1a Electrode 2 Conductive connection material 2A Hardened | cured material of a conductive component 2a Adhesive component 2b Conductive particle 3 Wiring member 3a Electrode 4 Heating stage 5 Crimp head 6 Base material 10 Thermocompression bonding apparatus 15 Adhesive film 18 Conductivity Connection material 18a Conductive particle-free layer 18b Conductive particle-containing layer 50 Wiring member connection structure.

Claims (4)

  In a wiring member connection structure in which a wiring member is connected to both a light receiving surface and a back electrode of a solar battery cell via a conductive connecting material, a conductive material having a higher elastic modulus than the back electrode side on the light receiving surface side. Wiring member connection structure using a conductive connecting material.   The wiring member connection structure according to claim 1, wherein the conductive connection material is a conductive film or conductive paste obtained by dispersing and containing conductive particles in a solder or insulating resin layer to impart conductive characteristics.   In the wiring member connection method in which the wiring member is connected to both the light receiving surface and the back electrode of the solar battery cell via the conductive connection material, the light receiving surface on the surface on which the electrode of the solar battery cell is formed A wiring member connecting method, comprising: arranging a conductive connecting material having a larger elastic modulus than the back electrode side, placing a wiring member on the conductive connecting material after provisional pressure bonding, and then thermocompression bonding.   The method for connecting wiring members according to claim 3, wherein the conductive connection material is a conductive film or conductive paste in which conductive particles are dispersed and contained in a solder or insulating resin layer to impart conductive characteristics.

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