JP2014207352A - Method for manufacturing solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a solar cell capable of fixing lead lines while suppressing increase in manufacturing cost.SOLUTION: In the method for manufacturing a solar cell, a solar cell lamination film ST1 is formed on a first main surface of a glass substrate 1. A part of the solar cell lamination film ST1 is removed and the first main surface of the glass substrate is exposed. Lead lines 10A, 10B are directly arranged on the exposed first main surface, and lead lines 10A, 10B are subjected to the ultrasonic vibration joining process.

Description

  The present invention relates to a method for manufacturing a solar cell, and more specifically to bonding between a substrate and a constituent member of a solar cell using an ultrasonic vibration bonding method.

  Conventionally, as a solar cell, a thin film solar cell formed by forming a power generation layer, an electrode layer, and the like on a glass substrate has been used. The thin-film solar cell is generally configured by connecting a plurality of solar cells in series.

  Moreover, in the structure of the thin film solar cell, electricity generated by each solar cell is collected by current collecting electrodes (bus bars) formed on both sides of the glass substrate. The electricity collected by the collecting electrode is taken out by a lead wire (lead wire). That is, the lead wire is connected to the current collecting electrode and is also connected to the terminal of the terminal box. With this connection configuration, the lead wire can guide the electricity collected by the current collecting electrode to the terminal box.

  Here, the collector electrode is electrically connected to the electrode layer of the solar battery cell formed on the glass substrate, and the lead wire is not directly connected to the solar battery cell (that is, the lead wire is The solar cell is electrically connected via the collecting electrode, but the solar cell itself and the lead wire itself are insulated).

  The arrangement method (drawing method) of the leader line has been conventionally proposed (see, for example, Patent Document 1).

  In the technique according to Patent Document 1, an insulating film is disposed on the electrode layer, and a lead wire (lead wire) is disposed on the insulating film. Here, Patent Document 1 discloses various arrangements of the leader lines so that the terminal box can be arranged at an arbitrary position.

  There are already a plurality of conventional techniques related to the present invention (that is, conventional techniques for connecting a collecting electrode and the like to a substrate using ultrasonic vibration bonding processing) (Patent Documents 2, 3, and 4). , 5, 6).

JP 2000-68542 A International Publication No. 2010/150350 JP 2011-9261 A JP 2011-9262 A JP 2012-4280 A JP 2012-4289 A

  In the manufacturing process of the thin film solar cell, after the collector electrode and the lead wire are disposed, the laminate sealing is performed. Here, when floating, bending, or the like is generated in the arranged leader line, the laminated sealing material rises and the waterproofness is impaired. In order to prevent such a problem from occurring, conventionally, the leader line is fixed with an adhesive tape or with an adhesive. Thus, conventionally, a fixing material for fixing the lead wire is required, which has been a factor in increasing the manufacturing cost of the solar cell.

  Then, an object of this invention is to provide the manufacturing method of the solar cell which can fix an extraction line, suppressing the increase in manufacturing cost.

  In order to achieve the above object, a method for manufacturing a solar cell according to the present invention includes (A) a step of forming a solar cell laminated film on a first main surface of a substrate, and (B) the solar cell laminated film. Forming a current collecting electrode that collects light generated by the solar cell multilayer film electrically connected to the solar cell multilayer film; and (C) removing a part of the solar cell multilayer film and (D) a step of directly arranging a lead wire for drawing out electricity collected by the current collecting electrode on the first main surface exposed in the step (C); E) a step of fixing the lead wire to the first main surface of the substrate by performing an ultrasonic vibration bonding process on the lead wire.

  The manufacturing method of the solar cell according to the present invention includes (A) a step of forming a solar cell laminated film on the first main surface of the substrate, and (B) the solar cell laminated film electrically connected. A step of forming a collecting electrode for collecting light generated by the solar cell laminated film; and (C) a step of removing a part of the solar cell laminated film and exposing the first main surface of the substrate; (D) a step of directly arranging a lead line for drawing out electricity collected by the current collecting electrode on the first main surface exposed in the step (C); and (E) exceeding the lead line. And a step of fixing the leader line to the first main surface of the substrate by performing a sonic vibration bonding process.

  In this manner, by arranging the leader line directly on the glass substrate and performing ultrasonic bonding treatment, the leader line can be firmly joined and fixed to the glass substrate. By fixing the lead wire, it is possible to prevent the lead wire from being bent during the lamination process. Further, when the leader line is fixed, a fixing material such as an adhesive tape, an adhesive, or solder is unnecessary. Thereby, the manufacturing cost of a solar cell can be reduced significantly.

2 is a plan view showing a configuration example of a solar battery cell formed on a first main surface of a glass substrate 1. FIG. 2 is a cross-sectional view showing a configuration example of a solar battery cell formed on a first main surface of a glass substrate 1. FIG. It is a perspective view for demonstrating a series of processes of the manufacturing method of the solar cell which concerns on this Embodiment. It is a perspective view for demonstrating a series of processes of the manufacturing method of the solar cell which concerns on this Embodiment. It is a perspective view for demonstrating a series of processes of the manufacturing method of the solar cell which concerns on this Embodiment. It is an expanded sectional view which shows the example of the specific structure of the chip | tip used by ultrasonic bonding process. It is an expanded sectional view which shows the other example of the specific structure of the chip | tip used by ultrasonic bonding process. It is a perspective view for demonstrating a series of processes of the manufacturing method of the solar cell which concerns on this Embodiment.

  In the present invention, an ultrasonic bonding method (ultrasonic (vibration) bonding process) in which ultrasonic vibration is applied in the horizontal direction while applying pressure in the vertical direction is adopted for bonding of the lead wires disposed in the solar cell. Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

<Embodiment>
First, a transparent substrate 1 (hereinafter referred to as a glass substrate 1) is prepared. And on the 1st main surface of the said glass substrate 1, the surface electrode layer 2, the electric power generation layer 3, and the back surface electrode layer 4 are each formed in a predetermined pattern shape. The basic configuration of the thin-film solar cell is created through this process. An insulating protective film may be laminated above the first main surface so as to cover all of the front electrode layer 2, the power generation layer 3, and the back electrode layer 4. In the following, for the sake of simplification of explanation, the explanation will proceed without including the protective film.

  Here, a laminated structure in which the front electrode layer 2, the power generation layer 3, and the back electrode layer 4 are formed in this order on the first main surface of the glass substrate 1 (a protective film is also formed). In this case, the whole (including the protective film) is referred to as a solar cell laminated film.

  Moreover, although the glass substrate 1 has a 1st main surface and the 2nd main surface facing the said 1st main surface, light injects from the 2nd main surface side of the glass substrate 1 here. A type solar cell will be described.

  FIG. 1 is a plan view showing a basic configuration of a thin film solar cell produced by the above process. FIG. 2 is a cross-sectional view taken along the line AA of FIG.

  As can be seen from FIGS. 1 and 2, the front electrode layer 2, the power generation layer 3 and the back electrode layer 4 are each formed in a stripe shape. Moreover, as shown in FIG. 2, the unit solar cell P1 is comprised by the unit laminated structure in which the surface electrode layer 2, the electric power generation layer 3, and the back surface electrode layer 4 are laminated | stacked in the said order. In each unit solar cell P1, the front electrode layer 2 and the back electrode layer 4 are electrically connected to the power generation layer 3, respectively.

  In addition, as shown in FIG. 2, the power generation layer 3 and the back electrode layer 4 constituting one unit solar cell P1 are electrically connected to the surface electrode layer 2 constituting the other unit solar cell P1, respectively. ing. Here, the other unit solar cell P1 is a unit solar cell adjacent to one unit solar cell P1. As can be seen from the configuration, as shown in FIG. 2, a plurality of unit solar cells P1 are directly electrically connected in the left-right direction of FIGS.

Here, the thickness of the glass substrate 1 is a thin film substrate of about 4 mm or less, for example. The surface electrode layer 2 is made of a conductive film having transparency, and for example, ZnO, ITO, or SnO ₂ can be adopted. Moreover, the thickness of the surface electrode layer 2 is, for example, about several tens of nm.

  The power generation layer 3 is a photoelectric conversion layer that can convert incident light into electricity. The power generation layer 3 is a thin film layer having a film thickness of about several μm (for example, 3 μm or less). The power generation layer 3 is made of, for example, silicon.

  The back electrode layer 4 can employ a conductive film containing silver, for example. The thickness of the back electrode layer 4 is, for example, about several tens of nm.

  FIG. 3 is a perspective view showing a state in which the solar cell laminated film ST1 is formed on the first main surface of the glass substrate 1. As shown in FIG. In FIG. 3, the solar cell laminated film ST1 is illustrated by sand.

  Here, the following names are defined for ease of explanation.

  As shown in FIG. 3, the first main surface of the glass substrate 1 has rectangular end edges L1, L2, L3, and L4. The said edge part L1, L2, L3, L4 is comprised from the 1st edge part L1, the 2nd edge part L2, the 3rd edge part L3, and the 4th edge part L4. .

  In the configuration illustrated in FIG. 3, the first end L1 and the second end L2 face each other and run in parallel, and the third end L3 and the fourth end The side portions L4 face each other and run in parallel. In the configuration example shown in FIG. 3, the first end side portion L1 intersects the third end side portion L3 and the fourth end side portion L4 perpendicularly, and the second end side portion L2 Is also perpendicular to the third end side L3 and the fourth end L4.

  Now, after solar cell laminated film ST1 formation, the process which removes solar cell laminated film ST1 which has leaked to each end surface (each side surface) of the glass substrate 1 is performed. Here, in the case of the said process, as shown in FIG. 4, in the 1st edge part L1 side, the solar cell formed on the 1st main surface along the said 1st edge part L1 The laminated film ST1 is partially removed, and a glass substrate partial exposure process for exposing a part of the first main surface of the glass substrate is also performed. Here, as the glass substrate partial exposure process, for example, laser trimming, sandblasting, or the like can be employed.

  By the said glass substrate partial exposure process, as shown in FIG. 4, in the 1st edge part L1 side (contacting 1st edge part L1) of the 1st main surface, the said 1st edge part A glass substrate exposed portion 1E is formed along L1. In the glass substrate exposed portion 1E, the glass substrate 1 of the first main surface is exposed.

  Next, referring to FIG. 5 (FIG. 5 is a configuration diagram after the ultrasonic bonding process described later is performed), the lead wires 10A and 10B are placed on the glass substrate exposed portion 1E in the first manner. It arrange | positions along the edge part L1.

  Here, leader line 10A, 10B is not made to contact solar cell laminated film ST1. As is clear from the above steps, the lead wires 10A and 10B are in direct contact with the first main surface of the glass substrate 1 exposed from the solar cell stacked film ST1. Further, the lead wires 10A and 10B themselves are not electrically connected directly to the solar cell laminated film ST1 itself.

  As described above, the lead wires 10 </ b> A and 10 </ b> B are lead wires that draw electricity under current collection from the current collecting electrodes described later. In addition, as the lead wires 10A and 10B, for example, aluminum, copper, and a conductor obtained by plating copper with silver or the like can be employed.

  After the leader lines 10A and 10B are arranged on the glass substrate exposed portion 1E, an ultrasonic bonding method is applied to the upper surfaces of the leader lines 10A and 10B in a spot manner. The ultrasonic bonding is preferably performed using, for example, a bonding tool having a chip having a predetermined shape described later.

  Specifically, the chip is brought into contact with the upper surfaces of the lead wires 10A and 10B, and a predetermined pressure is applied in the contact direction (the direction of the glass substrate 1). And the said chip | tip is ultrasonically vibrated in the horizontal direction (direction perpendicular | vertical to a pressure application direction) in the said pressure application state. Thereby, leader line 10A, 10B can be directly joined and fixed on the 1st main surface of the glass substrate 1. FIG. The ultrasonic bonding process is performed at a plurality of locations on the upper surfaces of the lead wires 10A and 10B.

  The state after the ultrasonic bonding process is shown in the plan view of FIG. In FIG. 5, reference numeral 15 denotes an indentation 15 that has been subjected to ultrasonic vibration processing. As shown in FIG. 5, a plurality of indentations 15 exist in a spot-like manner (dotted) along the line direction of the leader lines 10 </ b> A and 10 </ b> B.

  In addition, as shown in FIG. 5, two lead wires 10A and 10B are provided. One lead line 10A extends from the third end side L3 side along the first end side L1 (that is, one end of one lead line 10A is the third end side. The other leader line 10B extends from the fourth end side L4 side along the first end side part L1 (that is, one of the other leader lines 10B). Is arranged on the third end side L4 side).

  Here, after the ultrasonic bonding process, a step of raising the other end portions 10T1 and 10T2 of the lead wires 10A and 10B with respect to the first main surface of the glass substrate 1 is performed. By this process, as shown in FIG. 5, the other end 10T1 of one leader line 10A and the other end 10T2 of the other leader line 10B stand up in the vertical direction on the glass substrate exposed part 1E. .

  The other end portion 10T1 of one lead wire 10A and the other end portion 10T2 of the other lead wire 10B face each other at a predetermined interval above the glass substrate exposed portion 1E. Further, the other end 10T1 of one lead wire 10A and the other end 10T2 of the other lead wire 10B are connected to terminals of a terminal box (junction box or terminal box).

  That is, it is necessary to supply the electricity collected by the collecting electrode described later to a terminal box or the like existing outside. Therefore, it is necessary to dispose the lead wires 10A and 10B that electrically connect the collecting electrodes and external terminals disposed in the terminal box or the like.

  Moreover, the chip | tip of the predetermined shape mentioned above is as follows.

  As shown in FIG. 6, a plurality of flat portions 10 are separated from each other by a plurality of recesses 11 on the surface that contacts the members (leading lines 10 </ b> A, 10 </ b> B, etc.) of the chip 1 c. Here, the flatness of the flat portion 10 is formed with high accuracy. The interval P between the recesses 11 is set to about 1.0 mm or less, and the depth D to the deepest part of the recess 11 is set to about 0.15 mm or less. By adopting the chip 1c having the shape and performing the ultrasonic bonding method, it is possible to prevent the glass substrate 1 having a small thickness from being damaged.

  Alternatively, as shown in FIG. 7, fine uneven shapes may be formed in the plurality of flat portions 10 and the concave portions 11 on the contact side surface of the chip 1 c. By adopting the chip 1c having the configuration shown in FIG. 7, ultrasonic vibration bonding can be realized without hindrance by applying ultrasonic vibration with lower energy.

  Now, after the lead wires 10A and 10B are directly fixed on the glass substrate 1, the current collecting electrodes 20A and 20B are arranged at predetermined positions on the solar cell laminated film ST1. Here, as the current collecting electrodes 20A and 20B, for example, a conductor containing copper or aluminum can be employed.

  As shown in FIG. 8 (FIG. 8 is a diagram after performing ultrasonic bonding processing on the collector electrodes 20A and 20B, which will be described later), one collector electrode 20A is on the third end L3 side. , Extending along the third end side L3. Here, one end portion of the one collecting electrode 20A overlaps with one end portion of the one lead wire 10A on the first end side L1 side, and the one collecting electrode 20A The other end is on the second end L2 side. The other current collecting electrode 20B is extended along the fourth end side portion L4 on the fourth end side portion L4 side. Here, one end of the other collector electrode 20B overlaps with one end of the other lead wire 10B on the first end side L1 side, and the other collector electrode 20B The other end is on the second end L2 side. In addition, each collector electrode 20A, 20B is extended along the up-down direction of FIG.

  After the collector electrodes 20A and 20B are arranged on the solar cell laminated film ST1, the ultrasonic bonding is performed in a spot manner on the upper surfaces of the collector electrodes 20A and 20B in the same manner as the joining process of the lead wires 10A and 10B. Apply processing.

  Specifically, the chip is brought into contact with the upper surfaces of the collecting electrodes 20A and 20B, and a predetermined pressure is applied in the contact direction (the direction of the glass substrate 1). And the said chip | tip is ultrasonically vibrated in the horizontal direction (direction perpendicular | vertical to a pressure application direction) in the said pressure application state. Thereby, current collection electrode 20A, 20B can be joined and fixed on solar cell laminated film ST1. The ultrasonic bonding process is performed at a plurality of locations on the upper surfaces of the current collecting electrodes 20A and 20B.

  The state after the ultrasonic bonding treatment is shown in the plan view of FIG. In FIG. 8, reference numeral 25 denotes an indentation 25 that has been subjected to ultrasonic vibration processing. As shown in FIG. 8, a plurality of indentations 25 are present in a spot-like manner (dotted) along the line direction of the collecting electrodes 20A and 20B.

  Note that the portion where one current collecting electrode 20A and one lead wire 10A overlap is also subjected to ultrasonic bonding treatment, fixing one current collecting electrode 20A and one lead wire 10A, and glass of one lead wire 10A. The certainty of fixing to the substrate 1 is improved. Similarly, the portion where the other collector electrode 20B and the other lead wire 10B overlap is also subjected to ultrasonic bonding processing, the other collector electrode 20B and the other lead wire 10B are fixed, and the other lead wire 10B The certainty of fixing to the glass substrate 1 is also improved.

  By the ultrasonic vibration treatment, the collecting electrodes 20A and 20B are electrically connected (joined) directly to the solar cell laminated film ST1. In this way, in the solar cell module, the current collecting electrodes 20A and 20B are electrically joined to the solar cell laminated film ST1, so that the current collecting electrodes 20A and 20B are electrically connected to the solar cell laminated film ST1. It functions as a bus bar electrode that is a “collecting electrode”.

  That is, the electricity generated by each unit solar cell P1 connected in series is collected in the current collecting electrodes 20A and 20B. Here, in FIG. 8, for example, one collecting electrode 20A functions as a cathode electrode, and the other collecting electrode 20B functions as an anode electrode.

  In addition, the collecting electrodes 20A and 20B are electrically joined to at least the back electrode layer 4 by ultrasonic bonding treatment (or the back electrode layer 4 and the power generation layer 3, or the back electrode layer 4 and the power generation layer 3 and the surface). Electrically joined to the electrode layer 2).

  Through the above steps including the ultrasonic bonding process, the collector electrodes 20A and 20B bonded to the solar cell laminated film ST1, and the collector electrodes 20A and 20B are connected to the first main surface of the glass substrate 1. The directly joined lead wires 10A and 10B can be disposed on the glass substrate 1 on which the solar cell laminated film ST1 is formed.

  As described above, in the solar cell manufacturing method according to the present embodiment, the solar cell stacked film ST <b> 1 is formed on the first main surface of the glass substrate 1. And a part of solar cell laminated film ST1 is removed, and the 1st main surface of the glass substrate 1 is partially exposed. Then, the leader lines 10A and 10B are directly arranged on the exposed first main surface, and ultrasonic vibration joining processing is performed on the leader lines 10A and 10B.

  As described above, the lead wires 10A and 10B are directly arranged on the glass substrate 1 and subjected to ultrasonic bonding treatment, whereby the lead wires 10A and 10B can be firmly bonded and fixed to the glass substrate 1. By fixing the strong lead wires 10A and 10B, it is possible to prevent the lead wires from being bent during the lamination process. Further, when the leader lines 10A and 10B are fixed, a fixing material such as an adhesive tape, an adhesive, or solder is unnecessary. Thereby, the manufacturing cost of a solar cell can be reduced significantly.

  Further, in the ultrasonic bonding process, it is only necessary to apply ultrasonic vibration for a very short period. Accordingly, for example, the invention according to the present embodiment can prevent waste of energy that constantly heats the soldering iron as compared with a case where solder fixing is employed. Further, when comparing the solder bonding process and the ultrasonic bonding process, the ultrasonic bonding process is a shorter time process. Therefore, in the invention according to the present embodiment, high efficiency of the bonding process can be realized.

  Here, after forming solar cell laminated film ST1 in the 1st main surface of the glass substrate 1, the process of removing solar cell laminated film ST1 which protruded from the 1st main surface is performed conventionally. In the manufacturing method of the solar cell according to the present embodiment, the glass substrate exposed portion 1E is provided by the glass substrate partial exposure process during the process. That is, the solar cell manufacturing method according to the present embodiment does not include an extra step.

  In addition, when the solar cell laminated film ST1 is formed, it is possible to form the solar cell laminated film ST1 having the glass substrate exposed portion 1E as a pattern. However, the formation of the solar cell laminated film ST1 having the pattern causes an increase in cost. Therefore, from the viewpoint of reducing the manufacturing cost, as described above, after the solar cell multilayer film ST1 is formed on the entire first main surface of the glass substrate 1, the solar cell multilayer film ST1 is partially removed. It is better to provide the glass substrate exposed portion 1E.

  In addition, it is also possible to arrange | position leader line 10A, 10B in the 1st main surface of the glass substrate 1, for example in the approximate center part. In this case, it is necessary to remove the solar cell stacked film ST1 other than the end side portion of the glass substrate 1 (in the above description, the first end side portion L1). However, when such a solar cell laminated film ST1 is removed, the solar cells are divided and the power generation efficiency is reduced.

  Therefore, in the method for manufacturing a solar cell according to the present embodiment, the solar cell stacked film ST1 in the end portion (in the above description, the first end portion L1) of the glass substrate 1 is disposed along the end portion. , Have been removed. And along the said edge part, leader line 10A, 10B is arrange | positioned and it is made to join to the glass substrate 1 directly.

  Therefore, it is possible to firmly join and fix the lead wires 10A and 10B to the first main surface of the glass substrate 1 while preventing a decrease in power generation efficiency of the solar cell.

  Further, the method for manufacturing the solar cell according to the present embodiment includes a step of raising the end portions 10T1 and 10T2 of the lead wires 10A and 10B with respect to the first main surface of the glass substrate 1. Accordingly, the lead wires 10A and 10B can be easily connected to the terminals of the terminal box.

  In addition, arrangement | positioning of leader line 10A, 10B demonstrated by the manufacturing method of the solar cell which concerns on this Embodiment, arrangement | positioning of current collection electrode 20A, 20B, ultrasonic bonding process, and the edge part of leader line 10A, 10B The startup processing of 10T1 and 10T2 and the like are automatically performed in the solar cell manufacturing apparatus.

  Moreover, although the solar cell of the type in which light injects from the 2nd main surface side of the glass substrate 1 was demonstrated above, also in the solar cell of the type which injects light from the 1st main surface side of the glass substrate 1. The present invention is applicable. That is, even in the case of the latter type of solar cell, the solar cell stacked film ST1 formed on the first main surface side is partially (more specifically, on the edge side of the glass substrate 1 It is also possible to remove the lead wires 10A and 10B on the first main surface of the glass substrate 1 that has been removed and exposed, and to perform ultrasonic bonding processing on the lead wires 10A and 10B. It is.

  In the case of the latter type of solar cell, the lead wires 10A and 10B are formed on the glass substrate 1 from the viewpoint of preventing light from the first main surface side from being blocked by the lead wires 10A and 10B. It is preferable to be disposed and bonded to the side of the edge.

1 Glass substrate 2 Surface electrode layer 2
3 Power generation layer 4 Back electrode layer 10A, 10B Lead wire 10T1, 10T2 (leader wire) end 15, 25 Indentation 20A, 20B Current collecting electrode 1E Glass substrate exposed portion L1 First end L2 Second end Part L3 Third edge part L4 Fourth edge part P1 Unit solar battery cell ST1 Solar battery laminated film

Claims (3)

(A) forming a solar cell laminated film on the first main surface of the substrate;
(B) forming a current collecting electrode that collects light generated by the solar cell laminated film and is electrically connected to the solar cell laminated film;
(C) removing a part of the solar cell laminated film and exposing the first main surface of the substrate;
(D) A step of directly arranging a lead line for drawing electricity collected by the current collecting electrode on the first main surface exposed by the step (C);
(E) The step of fixing the leader line to the first main surface of the substrate by performing an ultrasonic vibration bonding process on the leader line,
A method for manufacturing a solar cell. The step (C)
The step of removing the solar cell laminated film at the edge of the substrate along the edge.
The manufacturing method of the solar cell of Claim 1 characterized by the above-mentioned. (F) The method further includes a step of raising the end portion of the leader line with respect to the first main surface of the substrate.
The manufacturing method of the solar cell of Claim 1 or Claim 2 characterized by the above-mentioned.

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