TW202027292A - Solar cell and method for manufacturing solar cell - Google Patents

Abstract

The present invention relates to a solar cell and a method for manufacturing the solar cell, and aims to improve the efficiency of the solar cell by reducing the series resistance component and increasing the parallel resistance component.

The composition of the present invention is as follow: a finger electrode containing silver and lead on an insulating film is formed; after firing, an insulating fixed bar is formed on the insulating film with the finger electrode part or the marginal part as an opening; by the action of silver and lead contained in the finger electrode during firing, an electrically conductive passage is formed between the region and the finger electrode through the insulating film that is a film below the finger electrode; further, at the same time as firing, by the action of the insulating fixed bar or the glass material contained in the fixed bar, an insulating fixed bar with good adhesion and soldering is formed on the insulating film.

Description

Solar cell and solar cell manufacturing method

The present invention relates to a solar cell and a method for manufacturing a solar cell. The solar cell is formed on a substrate in a region that generates high electron concentration when irradiated with light, etc., and an insulating film that penetrates light, etc. is formed on the region, And a finger electrode is formed on the insulating film to take out the electrons from the area, and a plurality of finger electrodes are electrically connected to take out the electrons to the outside, and the solar cell has an insulating fixing strip Instead of the traditional bus-bar electrode.

Traditionally, in the design of solar battery cells, it is important to efficiently flow the electrons generated in the solar battery cells to the connected external circuit. In order to achieve this task, it is particularly important to reduce the resistance component of the part connected from the unit to the outside and to prevent the generated electrons from disappearing.

Therefore, the inventors of the present invention have applied for a technology (Japanese Patent Application 2016-015873, Japanese Patent Application 2015-180720), which uses vanadate glass of conductive glass as the bus bar electrode to connect the finger electrode with the external The resistance between the strips (leads) taken out is reduced, and the disappearance of the electrons concentrated in the bus bar electrode is reduced.

[Traditional Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Application 2016-015873

[Patent Document 2] Japanese Patent Application 2015-180720

However, it is still insufficient to use the above-mentioned conventional silver or conductive glass as the bus bar electrode to reduce the resistance between the connecting finger electrode and the strip (lead) connection taken out from the outside, and further improvement is needed to achieve it. The issue of high efficiency of solar cells.

In addition, there is also a need for an inexpensive, simple and high-efficiency solar cell structure and its manufacturing method.

Moreover, there are also eliminating or reducing the use of traditional conductive glass containing expensive silver, vanadium, and barium, and reducing or eliminating the use of lead (lead glass), so that the manufacturing cost of solar cells is further reduced and there is no The subject of pollution and simple structure.

In addition, there is a problem that the terminals on the back side and the surface of the solar cell substrate cannot be soldered easily, reliably, inexpensively, and firmly.

The inventors of the present invention focused on the situation where the top of the finger electrode is exposed on the insulating film, and found that the insulating glass with openings on the exposed finger electrode is formed with strong adhesion. When connected to the ribbon of the external terminal, the series resistance component becomes smaller, and the parallel resistance component of the electron leakage from the external terminal to the inside becomes The big structure and so on.

Therefore, while reducing the series resistance component between the finger electrode and the external terminal and increasing the parallel resistance component between the external terminal and the inside of the substrate, the insulating glass of an inexpensive material is used to form a fixing strip with openings instead of The traditional bus bar electrode materials are expensive materials such as silver and conductive glass, and external terminals are directly fixed on it, so that a high-efficiency, low-leakage current, simple and inexpensive solar cell can be manufactured.

Therefore, the inventors of the present invention provide a solar cell, which is formed on a substrate with an area that generates high electron concentration when irradiated with light, etc., and an insulating film that penetrates the light, etc. is formed on the area, and on the insulating film A finger electrode is formed to take out electrons from the area, and the electrons are taken out to the outside through the finger electrode. Among them, a finger electrode containing silver and lead is formed on an insulating film, and the finger The part of the electrode or the part with a margin is used as an opening, the insulating fixing strip is formed on the insulating film and then fired, and the finger electrode is lowered by the action of silver and lead contained in the finger electrode during firing The insulating film penetrates through to form a conductive path between the area and the finger electrode, and the insulating film is firmly formed by the insulating fixing strip or the glass material contained in the fixing strip while firing Fixing and welding good insulating fixing strip.

At this time, in terms of the part with a margin as the opening, the part of the predetermined width that is less affected by the error during the formation of the finger electrode and the insulating fixing strip is set as the opening.

Also, regarding the part with margin as the opening, it is set to be equal to or several narrow openings when the external terminal is ultrasonically welded to the finger electrode and the insulating fixing strip and the contact part of the tip of the ultrasonic soldering iron. So that the contact part of the front end does not directly contact the insulating film.

Moreover, the firing is based on the temperature and formation of firing the finger electrodes Among the temperature of the insulating fixing strip, the former is equal to or higher than the latter, and the temperature of the former is used.

In addition, the firing system is set to 1 second or more and 60 seconds or less.

Moreover, as the insulating glass material contained in the insulating fixing strip or the fixing strip, any one or more of phosphate glass and bismuth glass is used.

In addition, the welding material for welding the external terminal to the finger electrode and the insulating fixing strip contains at least one of tin, tin oxide, zinc, and zinc oxide.

In addition, the soldering material is added with one or more of copper, silver, aluminum, bismuth, indium, and antimony as an additive as necessary.

In addition, the welding system of the external terminal to the finger electrode and the insulating fixing strip was ultrasonic welding.

Furthermore, the external terminal system is formed as a strip-shaped strip.

In addition, aluminum or partially perforated aluminum is formed on the entire surface of the backside opposite to the front side where the aforementioned regions, insulating films, finger electrodes, and insulating fixing strips are provided on the substrate, and the external terminals on the backside Be welded or ultrasonic welded.

Furthermore, the external terminal on the back side is set at a position on the aluminum on the back side corresponding to approximately the same position as the insulating fixing strip on the front side or a part of a part of the hole, and the external terminal on the back side is welded or super Sonic welding.

In addition, it is assumed that no insulating fixing strip is formed on the insulating film, and the finger electrode and the insulating film corresponding to the finger electrode and the part where the fixing strip is not formed are directly welded or the lead wire with pre-soldering is welded. The formation of the bus bar electrode, or the formation of the bus bar electrode and the welding of the lead-out wire. The welding system is set to ultrasonic welding.

In the present invention, as described above, the upper part of the finger electrode is exposed on the oxide film, and the insulating glass with openings in the finger electrode is formed with strong adhesion, and if it is directly connected to the outside from above In the case of a strip of terminals, the series resistance component becomes smaller, and the parallel resistance component of electrons leaking from the external terminal to the inside becomes larger, which becomes a highly efficient solar cell.

In addition, tin (its oxide), zinc (its oxide), etc. are used as soldering materials, and when soldering (ultrasonic welding, etc.) of oxide film, insulating fixing strip, and tape, it is because of insulating fixing The welding adhesion of the strip is good, so it has the effect of stably prolonging the life of the bonding between the finger electrode and the oxide film and the strip.

Moreover, compared to the expensive structure of the bus bar electrode made of conventional silver materials, conductive glass, etc., it is possible to use an inexpensive insulating glass material to reduce a substantial cost.

In addition, conventional lead solder is the mainstream solar cell. By reducing the use of lead, it is possible to build an environmentally friendly manufacturing process.

Furthermore, the connection terminal can be firmly and reliably welded to the back side of the substrate of the solar cell using an inexpensive material.

In addition, by not forming an insulating fixing strip on the insulating film, but directly welding or welding the lead wire with pre-soldering to the part corresponding to the finger electrode and the part not forming the fixing strip, the formation of the bus bar electrode, Or the formation of the bus bar electrode and the welding of the lead wire (ultrasonic welding) can eliminate the bus bar.

1.11: Substrate (silicon substrate)

3.13: Nitride film (insulating film)

4: Aluminum film

5.12: Finger electrode (finger electrode)

6: Fixing strip (insulation)

61: Bus

61: Fixed strip area

7: Strip, wire (pre-welded)

71, 72: welding materials

14: Bus (silver)

141: Bus (conductive glass)

142: busbar (insulating glass)

15: Busbar (welded strip)

151: Busbar (welding material (welding strip))

S1 to S25: steps

Figure 1 is a configuration diagram (an overall appearance diagram) of an embodiment of the present invention.

Fig. 2 is a configuration diagram of an embodiment of the present invention (a schematic example of partially enlarged finger electrodes 5 and fixing bars 6 from the upper side of the wafer).

Fig. 3 is a configuration diagram of an embodiment of the present invention (a schematic cross-sectional view of the finger electrode 5 and the fixing bar 6 being enlarged from the side of the wafer).

Figure 4 shows the step flow of the present invention (Part 1).

Figure 5 shows the step flow of the present invention (Part 2).

Figure 6 shows the step flow of the present invention (Part 3).

Figure 7 shows the step flow of the present invention (Part 4).

Figure 8 shows a concrete example and a conventional example of the present invention.

Figure 9 is a flow chart of the glass integration of the present invention.

Figure 10 is a flow chart of the glass integration of the present invention.

Figure 11 shows examples of the phosphate glass and bismuth-based glass of the present invention.

Figure 12 is a flow chart of the insulating paste application of the present invention.

Figure 13 is an example of the composition of the insulating glass paste of the present invention.

Figure 14 is an example of the conditions of the screen used in the screen printing of the present invention.

Figure 15 shows an actual application example of the present invention.

Figure 16 is an explanatory diagram of the characteristics of the present invention (part 1-the reduction effect of series resistance component).

Fig. 17 is an explanatory diagram of the characteristics of the present invention (Part 2-the effect of reducing leakage current by the parallel resistance component).

Figure 18 is an explanatory diagram of the characteristics of the present invention (Part 3-Obtained by the fixing strip of insulating glass The increase effect of current and voltage).

Figure 19 is an explanatory diagram of the transition of the bus bars on the surface of the solar cell of the present invention.

Figure 20 is a flow chart illustrating the operation of the present invention (without pre-welding).

Figure 21 shows an example of the strap connection of the present invention.

Figure 22 is an example of metal wire connection of the present invention.

Figure 23 is an example of welding conditions of the present invention.

Figure 24 shows the welding conditions and successful welding examples of the metal wire of the present invention.

Fig. 25 is an explanatory diagram of the presence or absence of pre-welding and the presence or absence of solder supply in the ultrasonic welding of the present invention.

Figure 26 is an explanatory diagram of the ABS-F (Art Beam solar cell surface technology) of the present invention.

Fig. 27 is an explanatory diagram of the advantages/disadvantages of the ABS-F of the present invention.

Figure 28 is a comparative example of the I-V characteristics of each glass of the present invention.

Figure 29 is an example of temperature and humidity changes in the TC 1000 hours of the present invention.

Figure 30 is an efficiency comparison example (phosphate glass) of the present invention before and after TC 1000 hours.

Figure 31 is a comparative example of I-V characteristics before and after TC of the phosphoric acid glass of the present invention (No. 1).

Figure 32 is an EL comparative example before and after TC of the present invention (phosphate glass No. 1).

Figure 33 is an SEM observation example of the phosphoric acid glass of the present invention after TC.

Fig. 34 is a cross-sectional structure diagram of another embodiment of the present invention (the cross-sectional structure without insulating glass, directly after welding).

Figure 35 is an explanatory diagram of the transition of the bus bar of the present invention.

Fig. 36 shows an example of manufacturing the busbar of the present invention (Fig. 35(d)).

Figure 37 shows an example of the I-V characteristics of the present invention.

[Example 1]

Figures 1 to 3 are diagrams showing the structure of an embodiment of the present invention.

In FIGS. 1 to 3, the nitride film 3 is an insulating film formed on the substrate (wafer) 1.

The finger electrode 5 is formed by printing and sintering a paste of silver and lead (lead glass) on the nitride film 3, and penetrates the nitride film 3 by the well-known calcining to reach the high concentration electron region Conductive path between, and take out electrons to the outside (described later).

The fixing strip 6 is an insulating fixing strip provided in the present invention. The part of the finger electrode 5 is used as an opening to be firmly fixed to the nitride film 3, and at the same time, the welding of the external terminal (belt-shaped strip) becomes good It is also used to reduce the leakage of electrons taken out from the finger electrode 5 to the substrate (nitride film 3 etc.) (that is, to reduce the parallel resistance component), etc. (described later).

The fixing strip area 61 is an area where the insulating fixing strip 6 is formed (described later).

Fig. 1 shows an example of a schematic diagram of the finger electrode 5 and the insulating fixing strip 6 being enlarged from the upper side of the wafer.

In Fig. 1, the rectangular substrate (silicon substrate, wafer) shown in the figure is used by the experimenter. The size of the rectangle is 48mm (the value is one example).

As shown in the figure, the finger electrodes 5 are arranged in a large number at predetermined intervals in the lateral direction, and are sintered and sintered to form conductive paths between regions of high concentration of electrons (described later).

The fixing strip area 61 is an insulating fixing strip area 61, which is a region where the insulating fixing strip 6 described later is formed at a right angle to the finger electrode 5 with a predetermined width as shown by the broken line in the figure. area.

Fig. 2 shows an example of a schematic diagram of the finger electrode 5 and the insulating fixing strip 6 being enlarged from the upper side of the wafer.

In Fig. 2, the insulating fixing strip 6 is formed in the insulating fixing strip area 61 of Fig. 1. Here, as shown in the figure, a plurality of strip-shaped portions with the part of the finger electrode 5 as openings are provided By. Here, for example, as shown in the figure, a plurality of those having a width of 2.0 mm and a length of 1.2 mm are provided with an interval of about 0.5 mm from the finger electrode 5. The insulating fixing strip 6 is formed by screen printing, followed by sintering to firmly fix it to the nitride film 3 and at the same time make the soldering good (described later).

Fig. 3 shows an example of a schematic cross-sectional view of the finger electrode 5 and the insulating fixing strip 6 being enlarged from the side surface of the wafer.

In Fig. 3, the finger electrode 5 is screen-printed and sintered, and is sintered to penetrate through the underlying nitride film 3 to form a conductive path between the high-concentration electron region below and as shown in the figure. A protruding part of usually about 20 μm is formed upward as the upper part (head) (described later).

The insulating fixing strip 6 is used in the present invention. The insulating glass or insulating paste containing insulating glass is screen-printed, and the finger electrode 5 is heated at the same time when it is sintered, thereby making it melt and firm. The ground is fixed to the nitride film 3 and the surface is easily soldered (described later). The insulating fixing strip 6 is preferably electrically higher insulation (that is, the parallel resistance component is preferably larger), which is to prevent electrons flowing in the strip from leaking to the substrate or the like. The insulating fixing strip 6 is as shown in the figure. Compared with the height of the upper part (head) of the finger electrode 5 (here, about 20μm), it is formed to have a lower height (here, about 20μm or less) The method of adjustment (when screen printing is to adjust the concentration of insulating glass or insulating paste containing insulating glass, etc.) is better. borrow Therefore, when the strip 7 shown in the figure is welded (ultrasonic welding is preferable), the upper portion (head) of the finger electrode 5 can be completely welded to reduce the contact resistance (series resistance component). Moreover, the mechanical strength is enhanced (even if the strip 7 is stretched, it will not peel off).

The experimental department is as follows

‧Width of fixing strip 6: 2mm

‧The length of the tip of the ultrasonic soldering iron: 2mm

‧The width of the tip of the ultrasonic soldering iron: 2mm

About the distance between the finger electrode 5 and the insulating fixing strip 6 (the distance in the longitudinal direction)

‧The upper limit is set not to be too long than the length of the soldering iron tip in the operating direction (2mm in the above example) and so that the bottom of the soldering iron tip does not touch the nitride film 3, etc. and cause damage (determined by experiments).

‧The lower limit is set not to be too steep for the welding slope as shown in Figure 3, and to be within the overlap accuracy of screen printing without cutting the welding material (determined by experiment).

In addition, regarding the width of the finger electrode 5 and the insulating fixing strip 6

‧The upper limit is set to the strip width (the width of the fixed strip 6).

‧The lower limit is set to about 0.8 of the upper limit.

In addition, the ultrasonic welding system is set to approximately 2W. If it is too large, it will damage the N+ emitter (high concentration electron area). Since welding adhesion cannot be obtained when it is small (the welding adhesion is specified to be 0.2N or more, in the present invention, it is set to 0.5N or more), so the optimal W number is determined by experiment (it may be due to ultrasonic soldering iron (The length, width, etc. of the soldering iron tip) are different, so it is determined by experiment).

Here, the requirements for welding the insulating fixing strip 6 and the finger electrode 5 with the strip (external terminal) are the adhesion to the finger electrode 5 (silver) and the insulating fixing strip 6 (insulating glass). good.

‧As suitable welding materials, tin-zinc alloys, tin-copper alloys, tin-silver alloys, etc. are used.

‧When the strip (pre-welded) is ultrasonically welded to the insulating fixing strip 6 and the finger electrode 5, the ultrasonic output power is preferably about 2W as described above. With ultrasonic welding, excessive high temperature is not required. Moreover, it is not necessary to increase the temperature of the useless part outside the welding area, and it is possible to prevent the performance degradation caused by the useless temperature rise of the surrounding.

In addition, the strip (external terminal) is a wire with copper as the material in the center and the outer side is covered with soldering material (pre-soldering is completed).

‧Because the welding on the back side of the substrate (wafer) is coated with aluminum on the entire back side of the substrate, the strip is directly ultrasonically welded or formed into a conductive fixing strip (vanadate glass) Then the strip will be given.

In addition, when the solder material is mainly tin, zinc, etc., if low-temperature brittleness is expected, in order to avoid this, additives (copper, silver, etc.) are added as necessary (addition to become an alloy). In addition, aluminum, bismuth, indium, antimony, etc. are added as additives to improve wettability, improve oxidation properties, and make it easier to manufacture solder alloys, and add an appropriate amount as needed (determined by experiment).

In addition, the formation of the insulating fixing strip 6, in the experiment

‧It is formed by screen printing and sintering using phosphoric acid/zinc-based glass, bismuth-based glass or paste with these as the main body.

‧Examples of materials: insulating glass (phosphate/zinc-based glass, bismuth-based glass (refer to Figure 11), etc.) or insulating glass paste containing such glass.

‧Outline description: Melt all materials and rapidly cool them to produce insulating glass, and make them into powder to produce paste. The paste is screen-printed to form an insulating fixing strip 6 and sintering, and finally the insulating fixing strip 6 is formed.

The requirements for the formation of the insulating fixing strip 6 are to meet the following points. The material, the thickness of the screen printing, the sintering temperature, etc. are determined through experiments

(1) The adhesion to the welding material used is good

(2) Good electrical insulation

(3) Adhesion to the nitride film 3 is good.

Next, in the order of the flow of steps shown in Figs. 4 to 7, the steps of the configuration of Figs. 1 to 3 will be explained in detail.

Figures 4 to 7 show the process flow of the present invention.

In Fig. 4, the S1 system prepares a Si substrate (tetravalent). It is a wafer that is to be used as the substrate (quaternary valence) of solar cells.

S2 produces P-type (trivalent) substrate 1. This is by diffusing boron and the like on the Si substrate (tetravalent) of S1 to form a P-type (trivalent).

S3 system diffuses phosphorus (pentavalent) to produce N+ type on the surface. Thereby, it is possible to manufacture a high-concentration electron region (N+ type).

In FIG. 5, S4 forms a nitride film 3 on the N+ region (high electron concentration region) on the front side of the substrate 1. The nitride film 3 is usually about 60 nm. Thereby, the N+ region (high electron concentration region) is protected by the nitride film 3.

In addition, in the S4 system, the aluminum film 4 is formed on the back side of the substrate 1 by vapor deposition, sputtering, or the like. The aluminum film 4 becomes the electrode part on the back side of the solar cell.

S5 is for printing finger electrodes. It uses a paste made of silver and lead glass to screen-print the shape of the finger electrode 5 in the first to third figures.

S6 system is performed to volatilize the solvent. It is heated at 100 to 120°C for about 1 hour to completely remove the solvent contained in the paste after screen printing.

In S7 of Fig. 6, the insulating fixing strip 6 is printed. It is screen-printed using an insulating paste containing insulating glass or insulating glass to form the shape of the insulating fixing strip 6 shown in Figs. 1 to 3 above.

S8 is used for volatilizing the solvent of the insulating fixing strip. It is heated at 100 to 120°C for about 1 hour to completely remove the solvent contained in the insulating paste after screen printing.

S9 series are fired. It is fired according to the condition that the finger electrode 5 will produce fire-through. In detail, in S5 and S6, a paste composed of silver and lead glass (silver/lead glass paste) is used to screen-print the finger electrode 5 on the nitride film 3, and in S7 and S8 Using an insulating paste containing insulating glass or insulating glass, screen printing the insulating fixing strip 6 on the nitride film 3 in a differently repeated manner, and in this state, the two are the same When firing (heating). The firing conditions are as described above. If the firing temperature of the former (fire through caused by silver/lead glass paste) and the temperature of the latter (dissolution/fixation of insulating glass paste) (a kind of brazing temperature) temperature)), the former is higher than the latter or equal to the requirement, and the former’s firing temperature (fire-through firing temperature) is used for firing. Specifically, the firing is performed in the range of, for example, 750°C to 850°C in the range of 1 to 60 seconds (heating is performed using a far-infrared lamp, and the optimal conditions are determined by experiments).

Through these steps, it is possible to simultaneously achieve (1) the finger electrode 5 burns through the nitride film 3, and (2) the insulating fixing strip 6 is firmly fixed to the nitride film 3 and the surface becomes easy The remarkable effect of welding.

The S10 system in Figure 7 is pre-welded. As shown in Fig. 3 above, from the finger electrode 5 and the insulating fixing strip 6 after firing in S9, the ultrasonic soldering iron is used for pre-welding of the welding material.

The S11 system performs strip welding. It is to weld the strip after pre-welding in S10 (for details, refer to the description of Figure 3 above). Moreover, it is also possible to directly perform ultrasonic welding on the finger electrode 5 and the insulating fixing strip 6 using a pre-welded strip.

The S12 system carries out the strip welding on the back side. The strip is ultrasonically welded to the aluminum film 4 formed on the back side of the substrate 1 in S4 in FIG. 5. For the strip welding on the back side, the pre-welded strip can be directly ultrasonically welded to the aluminum film 4 of S4 in Figure 5, or conductive glass (such as vanadate glass) can be screen-printed with openings. After sintering the back side to make it firmly fixed, ultrasonic welding is performed on both the tape and the insulating fixing strip 6 and the aluminum film 5 to increase the strength.

Fig. 8 shows a concrete example and a conventional example of the present invention.

Figure 8(a) is a photograph showing a separate example of the present invention. This is an example in which the insulating fixing strip 6 is separated from the finger electrode 5 and the insulating fixing strip is divided in the longitudinal direction (referred to as a separate type).

Figure 8(b) is a photo showing an example of the traditional touch strip type. This is an example in which the conductive fixing strip is connected to the finger electrode 5, and the conductive fixing strip is divided along the length direction (referred to as a touch strip type).

Among the above, the touch strip type of Fig. 8(b) cannot achieve the accuracy (positional alignment, etc.) during screen printing of the conductive fixed strip and the accuracy during screen printing of the finger electrode 5 ( When the position alignment, etc.) is larger, it is better to select the separate type of Fig. 8(a) of the present invention in such a way that the accuracy errors will not cause any influence.

In the case of the separate type shown in Fig. 8(a), as mentioned above, the size of the soldering iron tip (in the longitudinal direction) during ultrasonic welding is slightly smaller because it can prevent the soldering iron tip from touching The nitride film 3 underneath is damaged, etc., so good welding can be performed.

Figure 8(c) shows an example of finger electrodes under the conventional bus bar electrodes. In this conventional case, a paste containing silver and lead glass is screen-printed on the strip-shaped bus bar electrode in a manner orthogonal to the finger electrode and then fired. Therefore, the finger electrode cannot be formed from The bus bar electrode protrudes and the strip cannot be directly welded to the finger electrode of the present invention. As a result, electrons are extracted to the outside through the finger electrode-bus bar electrode-strip, so the resistance of the path cannot be reduced ( The series resistance component), as a result, has the disadvantage of lowering the efficiency of the solar cell.

Figure 9 shows the glass manufacturing flow chart of the present invention. It is a manufacturing flow chart of insulating glass that forms the insulating fixing strip 6 of the aforementioned Fig. 2 and the like.

In Figure 9, the S21 system mixes glass components. For example, the glass components of insulating glass (such as ZnO, P ₂ O ₅ , CaO, B ₂ O ₃ .ZnO, etc.) of insulating glass such as phosphoric acid/zinc-based glass or bismuth-based glass in Fig. 11 described later are blended.

S22 is added to the crucible and stirred. In S21, each component in powder form is added to the crucible, fully stirred and uniformly mixed.

S23 is placed in an electric furnace at 1000°C. In S22, the powder of each glass component is added to the crucible, stirred and fully blended, and then placed in an electric furnace at 1000°C (the crucible can be placed in the electric furnace and heated at 1000°C). In addition, the heating temperature is determined through experiments to determine the optimal temperature.

The S24 system is heated for 1 hour. It is placed in an electric furnace at 1000°C in S23, and then heated for 1 hour (stirring is performed during heating).

S25 is taken out from the electric furnace to the outer iron plate at room temperature and quenched. Thereby, insulating glass blocks can be manufactured.

In accordance with the above S21 to S25 sequence, insulating glass blocks such as phosphoric acid/zinc-based glass and bismuth-based glass in Fig. 11 described later can be manufactured. This insulating glass block is pulverized into a predetermined particle size using a well-known method, and used as a material of the insulating glass paste.

Fig. 10 shows an example of the composition/condition of the insulating glass of the present invention. This is an example of the components, conditions, and the like required when insulating glass is used for the insulating fixing strip 6 of the solar cell shown in FIG. 2.

In Figure 10, the insulating glass used in the insulating fixing strip 6 of solar cells is required to have water resistance, light resistance, insulation, and adhesion (nitride film, welding adhesion), etc., specifically Figure 10 shows the following conditions and ingredient restrictions.

It is formed by firing the fixing strip 6 in Figure 2 using insulating glass that satisfies the above conditions, composition restrictions, etc., whereby the insulating fixing strip 6 is strongly fixed to the nitride film, even if the strip Ultrasonic welding is carried out on the insulating fixing strip 6, and the insulating fixing strip 6 is also provided under the strip, and the resistance component (called parallel resistance component) inside the substrate becomes extremely large, which is taken out from the finger electrode 5. The ratio of electrons to the strips leaking into the substrate through the parallel resistance component may become extremely small, and as a result, the efficiency (current × voltage) of the solar cell can be reduced (refer to Figures 16 to 19 described later).

Fig. 11 shows examples of the phosphate glass and bismuth-based glass of the present invention. single Bits are% by weight.

In Fig. 11, examples 1 and 2 of phosphoric acid/zinc-based glass have the following components (% by weight) as shown in the figure.

In Fig. 11, examples 1 and 2 of bismuth glass have the following composition (weight%) as shown in the figure.

When insulating phosphoric acid/zinc-based glass or bismuth glass is produced from the above-mentioned components and used as a fixing strip 5 of a solar cell, the parallel resistance component can be efficiently reduced (refer to Figs. 16 to 19 described later).

Figure 12 shows a flow chart of the insulating paste application of the present invention. It is a flow chart showing the practical application of insulating paste composed of powder of insulating glass (phosphate/zinc-based glass. Bismuth glass) to the manufacture of fixing strips 5 for solar cells.

In Fig. 12, S31 screen-prints the insulating paste to print the pattern of the fixing strip 5. It uses insulating paste to screen-print the fixing strip 6 of Fig. 2 on the fixing strip area 61 of the aforementioned Fig. 1 for screen printing.

S32 is placed in a dry atmosphere (2 to 24 hours). The drying system for example

‧Use dry box (box and container for drying) etc.

‧This step may be omitted according to the situation.

S33 is to volatilize the solvent ((3) organic solvent) of the insulating paste after printing. For example, under the following conditions:

‧In the temperature range of about 40 to 100℃,

‧Heat treatment (drying treatment) (solvent evaporation step) for about 100 minutes.

Thereby, the solvent contained in the part of the fixing strip 6 of the solar cell on which the insulating paste has been screen-printed can be volatilized, and the fixing strip 6 of the solar cell can be attached to the base part.

S34 is placed in a dry atmosphere (2 to 24 hours). The drying system for example

‧Use dry box (box and container for drying) etc.

‧This step may be omitted according to the situation.

S35 is firing (sintering). The conditions are

‧For one example of far infrared sintering device:

Sintering is performed in the range of 340 to 900°C in the range of 3 to 60 seconds.

Moreover, it is only required to be in the range of about 1 (preferably 3) to 60 seconds. In addition, an infrared sintering device may be used instead of the far infrared sintering device. As sintering using far infrared rays and infrared rays, although the lamp (far infrared lamp) is used in the above example, it is not limited to this, as long as it is a ceramic heater, laser, etc. that can emit infrared or far infrared rays. . In addition, when sintering is possible at the temperature and sintering time within the above-mentioned range, other means may be used (for example, hot air heated by gas such as air may be used).

In addition, screen printing and firing may be performed several times to adjust the film thickness.

According to the above, in the experiment system, the insulating fixing strip 5 of the solar cell was screen-printed using the insulating insulating paste of the present invention and sintered within the above-mentioned range (temperature, sintering time). The efficiency (conversion efficiency) of solar cells such as powder 100%) is better (refer to Figure 16 to Figure 19 described later).

Fig. 13 shows an example of the composition of the insulating glass paste of the present invention. Fig. 13 is an example of the composition of insulating glass paste, which is a paste composed of a main material, an organic material, an organic solvent, and a resin. The experiment was produced using the following composition as shown in the figure.

In Figure 13, the ingredients, concentration range (weight%), and remarks are as shown below.

The above composition is sufficiently kneaded to produce an insulating glass paste, and the fixing bar in accordance with the flow chart of Fig. 12 is printed, dried, and sintered to produce the insulating fixing bar 6 of Fig. 2.

Figure 14 shows an example of the conditions of the screen used in the screen printing of the present invention.

As shown in Figure 14, the conditions of the mesh screen are for example

‧Mesh wire diameter: 16μm

‧Mesh: 325pcs/inch

‧Opening degree (opening): 62μm

‧Space rate: 63%

Here, when the film thickness of the insulating fixing strip 6 of the solar cell is to be controlled, it is performed by changing the conditions of the aforementioned mesh or changing the concentration of the organic solvent in the insulating paste.

Figure 15 shows a practical application example of the present invention. It shows the use of silver paste (containing lead) to screen-print the finger electrodes on the nitride film formed on the substrate of the solar cell, and use the insulating glass paste to screen-print the fixing strip 6 and then burn both at once. An example of a photograph after the finger electrode 5 and the insulating fixing strip 6 are formed simultaneously.

Set here

‧The width of the finger electrode 5 is 0.1mm

‧The width×length of the insulating fixing strip 6 is 0.5mm×0.7mm

‧The distance between the finger electrode 5 and the fixed strip 6 is 0.3mm.

Here, the insulating fixing strip 6 uses phosphoric acid-based glass, and in order to clearly photograph the glass, the photograph is illuminated with yellow light. The original glass is colorless and transparent.

In addition, on the finger electrodes 5 and the insulating fixing strip 6 manufactured as shown in the figure, the pre-welded copper tape is ultrasonically welded in the longitudinal direction to weld the leads.

According to the above, the first is to directly ultrasonically weld the copper tape to the finger electrode 5, which can eliminate the traditional bus electrode (silver) intervening between the finger electrode 5 and reduce the series resistance component.

Moreover, the second is to use an insulating fixing strip 6 instead of the conventional bus bar electrode (silver, conductive glass), which can reduce the leakage of electrons from the bus bar electrode (silver, conductive glass) to the inside of the substrate (that is, extremely Increase the parallel resistance component to reduce leakage). At this time, the insulating fixing strip 5 is strongly fixed to the nitride film underneath, and the insulating fixing strip 5 can be welded with a copper tape by ultrasonic welding and the copper strip can be firmly fixed to the substrate.

Next, using Figures 16 to 19, it is explained in detail that the reduction of the first series resistance component of the present invention and the extreme increase of the second parallel resistance component of the present invention can reduce leakage, thereby improving the solar cell’s performance. Conversion efficiency matters.

Fig. 16 is an explanatory diagram showing the characteristics of the present invention (part 1-reduction effect of series resistance component). The vertical axis shows the current output from the solar cell, and the horizontal axis shows the voltage output at this time. The solid I-V curve in the figure shows an example of the I-V curve (insulating fixing strip 5) obtained by using the insulating fixing strip 6 of the present invention (Fig. 15), and the dashed line shows using traditional conductivity An example of the I-V curve (traditional conductive bus electrode) obtained by the bus electrode.

In Fig. 16, the larger ellipse schematically shows that by directly ultrasonically welding the strip to the finger electrode 5 to reduce the series resistance component and increase the current component. That is, because the present invention directly ultrasonically welds the strip (copper strip) to the protruding part of the finger electrode 5, the conventional bus bar electrode is eliminated between the finger electrode 5 and the strip and the corresponding resistance is eliminated (Series resistance) makes the corresponding series resistance component smaller. Therefore, Figure 16 schematically shows the situation where the current of the IV curve increases and moves upward.

Fig. 17 is an explanatory diagram showing the characteristics of the present invention (Part 2-the effect of reducing leakage current due to a larger parallel resistance component). The vertical axis and horizontal axis are the same as in Fig. 16.

In Fig. 17, the larger elliptical part schematically shows the use of insulating glass as the fixing strip 6 to fabricate the conventional conductive bus bar electrode to increase the parallel resistance component to reduce leakage current. That is, in the present invention, an insulating separation type fixing strip 6 is formed to replace the conventional conductive busbar electrode, and a strip (copper tape) is ultrasonically welded to the fixing strip 6. Therefore, there is an insulating fixing strip 6 between the strip and the substrate, which greatly increases the resistance of the strip to the inside of the substrate and reduces the leakage current, and the corresponding parallel resistance component becomes extremely large. Therefore, Figure 17 is schematically Shows that the voltage of the IV curve increases and moves to the right.

Fig. 18 is an explanatory diagram showing the characteristics of the present invention (part 3-the effect of increasing current and voltage by the fixing bars of insulating glass). The vertical axis and horizontal axis are the same as in Fig. 16.

In Fig. 18, the larger ellipse schematically shows the multiplication effect obtained by the larger ellipse in Fig. 16 and the larger ellipse in Fig. 17, that is, the reduction of the series resistance component The current increase, and the leakage current is reduced by the parallel resistance component becomes extremely large, and the product of the voltage rise increases.

Fig. 19 is an explanatory diagram showing the transition of the bus bar electrode on the surface of the solar cell of the present invention. It is an explanatory diagram showing the transition of the bus bar electrode on the surface of the solar cell filed by the inventors.

Figure 19(a) schematically shows the situation when a conductive glass busbar electrode is used. This application case is described in Japanese Patent Application 2016-015873, for example.

Figure 19(b) schematically shows the situation when a separate conductive glass bus bar electrode is used. This application case is described in Japanese Patent Application 2016-257471, for example. In the case of the bus bar electrode of the separated conductive glass, by using the separated conductive glass, the conversion efficiency of the solar cell is increased by 0.1 to 0.2% by reducing the series resistance (1).

Figure 19(c) schematically shows the situation when the fixing strip 6 (busbar) of the separated insulating glass of the present invention is used (the conductive busbar electrode is eliminated). In the case of the fixing strip 6 (bus bar) of the separated insulating glass, as described in Figs. 1 to 18, by using the separated insulating glass, the series resistance component is reduced, and ② The increase of the parallel resistance component reduces the leakage and the conversion efficiency of the solar cell increases by more than 0.2-0.4%.

Next, using Figures 20 to 25, we will describe in detail how to directly ultrasonically weld the strip or wire (metal wire) to which the solder is attached to the substrate, the film formed on the substrate, and the fixing strip , The order of the parts to be ultrasonically welded, such as the aluminum surface on the back surface, and the part with holes on the aluminum surface.

Figure 20 is a flow chart showing the operation of the present invention (without pre-welding).

In Fig. 20, S101 sets the temperature of the soldering iron, the wafer mounting table, and the ultrasonic oscillation frequency. Before ultrasonic welding is carried out, the following preparations are carried out.

‧ Soldering iron: Heat to a predetermined temperature (heat to the temperature at which the solder attached to the strip or wire will melt).

‧Wafer mounting table: Preheat the wafer mounting table of the substrate to a predetermined temperature (a lower temperature than the temperature at which the solder attached to the strip or wire will melt, such as 180°C (described later)).

‧Ultrasonic oscillation frequency, etc.: Ultrasonic waves of predetermined frequency and predetermined output power are adjusted by supplying ultrasonic waves from the soldering iron tip to the wafer of the substrate (for example, as described later, ultrasonic waves of tens of KHz and 1 to 6W are supplied to Adjust the way of the soldering iron tip).

S102 is to install the wafer in a predetermined position. It uses an automatic machine not shown in the figure to transport wafers, such as solar cells, to be ultrasonically welded with strips or wires to a predetermined position on a wafer mounting table that has been heated to a predetermined temperature in S101 to be fixed. It is preheated to a predetermined temperature (for example, 180°C) at a fixed instant.

S103 sends out the welding metal wire or strip. It is to use the automatic machine not shown in the figure to send the metal wire (wire) or strip pre-attached with solder to the predetermined position of the preheated preheated wafer that has been fixed at the predetermined position of the wafer loading table in S102 (The predetermined position of the substrate or the film on the substrate to be ultrasonically welded). The metal wire (wire) or ribbon is sent out from a reel or from a carrying box containing a plurality of metal wires or ribbons that have been cut to a predetermined length. In addition, especially because the metal wire may occasionally be cut due to twisting during feeding out of the reel, it is better to use an automatic machine to send out the metal wire (wire) that has been cut to a predetermined length from the loading box. This is not the case when using strips.

S104 series are ultrasonic welding. The wafer has been fixed on the wafer mounting table in S102 and has been preheated to a predetermined temperature (for example, 180°C), and it has been attached in S103 Under the state that the metal wire (wire) or strip with solder is supplied (or placed) on the wafer or the film (aluminum film, nitride film, glass film, etc.) formed on the wafer, ultrasonic welding The soldering iron tip of the soldering iron is gently pressed to supply ultrasonic waves while removing dust, etc., while melting the solder attached to the metal wire (wire) or strip, and the metal wire or strip and the wafer (substrate) or The film (film on the substrate) formed on the wafer is ultrasonically welded.

S105 identifies whether there is a wafer to be processed. In the case of YES, because there are still wafers to be processed, the subsequent wafer processing (processing from S102 to S104) is repeated in S106. In the case of NO, the processing of all wafers ends, so it ends.

According to the above, the metal wire (wire) or strip attached with solder in advance, and the film (film on the substrate) formed on the preheated wafer (substrate) or wafer will be attached to the metal wire or strip. The solder of the tape melts, and the ultrasonic welding can be directly performed on the wafer or the film on the wafer. Thereby, compared with the case where a metal wire or strip to which the aforementioned solder is not attached is ultrasonically welded to a substrate or a film on the substrate, the following advantages are provided.

1 In this example, since solder is attached to the metal wire or strip, there is no need for an automatic solder supply device, preheating device, etc.

2 Compared with pre-soldering the solder on the substrate or the film on the substrate, secondly, when the metal wire or strip is soldered, the pre-soldering step is unnecessary.

Figure 21 shows an example of strap connection of the present invention. It shows that according to the flow chart in Figure 20, the strip with solder attached is directly ultrasonically welded to the wafer (such as solar cell) or the film on the wafer, and the strip is firmly connected electrically and mechanically. Take the example.

Figure 21 (a) shows an example of the connection of the opposite finger surface, and Figure 21 (b) shows the Figure 21(c) shows the connection example to the aluminum surface on the back side.

Figure 21(a) shows an example of connection to the finger surface. Figure 21 (a-1) shows an example of ultrasonic welding of a strip on the finger surface, and Figure 21 (a-2) shows a view from the horizontal direction.

In Figure 21(a), the strip (the strip with solder attached) is shown in accordance with the flowchart in Figure 20, direct ultrasonic welding on the finger surface formed on the silicon substrate and the strip is charged Examples of flexible connection to the finger surface (finger electrode), and mechanically firmly connecting (fixing) the strip to the film (a nitride film or a glass film formed on the nitride film).

Figure 21(b) shows an example of connection to the silicon surface (substrate). Figure 21 (b-1) shows an example of ultrasonic welding of the strip on the silicon surface, and Figure 21 (b-2) shows the view from the horizontal direction.

In Figure 21(b), the strip (the strip with solder attached) is shown in accordance with the flow chart in Figure 20, direct ultrasonic welding on the silicon substrate and electrically connecting the strip to the silicon surface ( Substrate), and an example of mechanically firmly connecting (fixing) the strip to the silicon surface (substrate).

Figure 21(c) shows an example of connection to the aluminum surface on the back. Figure 21 (c-1) shows an example of ultrasonic welding of the strip on the aluminum back surface, and Figure 21 (c-2) shows a view from the horizontal direction.

In Figure 21(c), the strip (the strip with solder attached) is shown in accordance with the flow chart of Figure 20, showing direct ultrasonic welding on the aluminum surface on the back of the silicon substrate and the strip is electrically charged An example of connecting to the back aluminum surface and mechanically firmly connecting (fixing) the strip.

Fig. 22 shows an example of metal wire connection according to the present invention. It shows that the metal wire (wire) attached with solder is directly ultrasonically welded to the wafer (such as solar cell) or the film on the wafer according to the flow chart in Figure 20, and the metal wire is electrically and Mechanically firmly Connection example.

Figure 22(a) shows an example of connection to the finger surface, Figure 22(b) shows an example of connection to the silicon surface, and Figure 22(c) shows an example of connection to the back aluminum surface.

Figure 22(a) shows an example of connection to the finger surface. Figure 22 (a-1) shows an example of ultrasonic welding of metal wires on the finger surface, and Figure 22 (a-2) shows a view from the horizontal direction.

In Figure 22(a), the illustrated metal wire (metal wire with solder attached) shows the finger surface formed by direct ultrasonic welding on the silicon substrate according to the flow chart in Figure 20, and the An example of a metal wire electrically connected to the finger surface (finger electrode) and mechanically firmly connected (fixed) the metal wire to a film (a nitride film or a glass film formed on the nitride film).

Figure 22(b) shows an example of connection to the silicon surface (substrate). Figure 22 (b-1) shows an example of ultrasonic welding of metal wires on the silicon surface, and Figure 22 (b-2) shows a view from the horizontal direction.

In Figure 22(b), the metal wire (metal wire with solder attached) is shown in accordance with the flow chart of Figure 20, directly ultrasonic welding on the silicon substrate and electrically connecting the metal wire to the silicon Surface (substrate), and an example of mechanically firmly connecting (fixing) the metal wire to the silicon surface (substrate).

Figure 22(c) shows an example of connection to the aluminum surface on the back side. Figure 22 (c-1) shows an example of ultrasonic welding of metal wires on the aluminum back surface, and Figure 22 (c-2) shows a view from the horizontal direction.

In Figure 22(c), the metal wire (metal wire with solder attached) is shown in accordance with the flow chart in Figure 20, directly ultrasonically welded to the aluminum surface on the back of the silicon substrate and electrically connected to the metal wire Is connected to the back aluminum surface, and the metal wire is mechanically firmly connected (fixed) example.

Fig. 23 shows an example of welding conditions of the present invention. This is an example of the welding conditions used in the ultrasonic welding shown in the aforementioned Figures 20, 21, and 22. As shown in the figure, the sample, the ultrasonic output power, the ultrasonic frequency, the soldering iron temperature, and the stage temperature (wafer holding table temperature) are set as shown below.

Figure 24 shows the welding conditions and successful welding examples of the metal wire of the present invention.

、0.4mm

、0.3mm

、0.2mm

顯示進行實驗時的成功支數例，得到如圖示之下述的結果。 Figure 24 (a) shows an example of the number of successful entries/total number of entries. Here, as the cross-sectional shape of the metal wire, as shown in the figure, for 0.5mm

, 0.4mm

, 0.3mm

, 0.2mm

Shows the number of successful cases in the experiment, and the following results are obtained as shown in the figure.

Here, (a-1) "Solder coating with a thickness of about 10 μm" refers to a metal wire (copper metal wire) with about 10 μm solder (attached by solder coating). (a-2) "The crushed shape of the aforementioned metal wire" is a slightly crushed O-shaped metal wire "approximately 10 μm thick solder coated" as explained in Fig. 24(b) described later. (a-3) "Pre-soldering, copper wire ○ shape" is a result of pre-welding on the substrate in advance, and ultrasonic welding of a copper wire ○ shape metal wire.

、0.4mm

、0.3mm

、0.2mm

依照前述第20圖的流程圖，實驗對基板(晶圓)進行超音波焊接之結果，得到如下述的結果。 As mentioned above, the cross-sectional diameter of the metal wire is 0.5mm

, 0.4mm

, 0.3mm

, 0.2mm

According to the flow chart in Figure 20, the results of the ultrasonic welding of the substrate (wafer) were obtained as follows.

(1) It is difficult to ultrasonically weld the metal wire system that maintains the ○ shape of (a-1), but all other than this can be ultrasonically welded (electrical and mechanical connections become good).

的金屬線(使焊料附著在銅線為0.5mm

的表面而成之金 屬線)為太硬，對晶圓進行超音波焊接時，該晶圓有產生裂紋或剝落之情形，在操作上有困難。為了使用該金屬線，有進行退火等使其柔軟化之必要性。 (2) 0.5mm

The metal wire (so that the solder is attached to the copper wire is 0.5mm

The surface of the metal wire) is too hard. When the wafer is subjected to ultrasonic welding, the wafer may crack or peel off, which is difficult to handle. In order to use this metal wire, it is necessary to perform annealing or the like to make it soft.

(3) As shown in (a-3), it is clear that if the substrate is pre-soldered (ultrasonic pre-soldering), even a copper wire ○-shaped metal wire can be ultrasonically soldered to the substrate.

Figure 24(b) is an explanatory diagram showing the crushed metal wire. This is an explanatory diagram showing "(a-2) Crushing shape of the aforementioned metal wire" in the aforementioned Fig. 24(a).

Figure 24 (b-1) shows an example of a copper wire ○-shaped metal wire, and Figure 24 (b-2) shows an example of a crushed shape.

In Figure 24 (b-2), it can be clearly understood through experiments that the copper wire ○-shaped metal wire in Figure 24 (b-1) is slightly crushed up and down in the diameter direction as shown. , When the part that is in contact with the lower substrate is about 100 to 200 μm or more, stable soldering can be performed (Ultrasonic soldering according to the flowchart in Figure 20 is possible).

Fig. 25 is an explanatory diagram showing the ultrasonic soldering of the present invention (presoldering, solder supply, etc.). Here, the vertical axis shows the difference between with and without pre-welding. It is the part of the substrate (such as a wafer or a film formed on the surface of the wafer) that is to be ultrasonically welded to a metal wire or strip. The pre-soldering is different from the case where the pre-soldering is not performed. The difference is none.

Also, the horizontal axis shows the difference between metal wires or strips and no welding. It is the case that pre-soldering (or solder coating) is performed on the surface of the metal wire or strip, and the case that the soldering is not performed is no.

In Fig. 25, for the combination of pre-welding and metal wire or strip without welding, when ultrasonic welding is performed according to the flowchart in Fig. 20, the following practice shown in the figure is obtained. The results.

Here, if explained in detail, the following results are obtained for the four combinations (1), (2), (3), and (4).

(1) The following results can be obtained with "pre-welded" and "metal wire or strip welding":

1 Stable operation

2 Even ○-shaped metal wires can be welded

It is a part of the pre-soldered part of the substrate (wafer) or the film formed on the substrate that is to be ultrasonically welded with the metal wire or strip. The part of the pre-soldered metal wire or strip The experimental results of ultrasonic welding are given. It can work stably even with ○-shaped metal The wires can also be welded well (electrically connected and mechanically firmly connected).

(2) The following results can be obtained with "no pre-welding" and "metal wire or strip welding":

1 ○The metal wire or strip after the shape is crushed is close

2 ○The adhesion of the shape metal wire is unstable

3 There is a problem with the adhesion of the peeled part of the attached solder

It is the part of the substrate (wafer) or the film formed on the substrate to be ultrasonically welded to the metal wire or strip that is not pre-soldered by ultrasonic welding, and the welded metal wire or strip Experimental results during ultrasonic welding. It is possible to obtain a result that the adhesion of the metal wire or the strip after the ○-shape crushing is good, the adhesion of the ○-shape metal wire is unstable, and the adhesion of the solder peeling after adhesion is problematic.

(3) The following results can be obtained with "pre-welded" and "metal wire or strip without welding":

1 According to the conduction of heat, the welding material may not adhere evenly

It is a part of the film formed on the substrate (wafer) or the substrate to be ultrasonically welded with metal wires or strips. The part of the film that is pre-soldered by ultrasonic welding in advance, and the unsoldered metal wire or strip With the experimental results of ultrasonic welding. It is possible to obtain the result that the solder material is not uniformly adhered according to the conduction of heat. That is, the solder is not attached to the metal wire or strip, because the part of the substrate to be soldered is pre-soldered and because the metal wire or strip is gently pressed by the soldering iron tip while performing ultrasonic welding, Therefore, according to the heat conduction method of the heat conduction path of the soldering iron tip, the metal wire or the strip, and the pre-soldering part on the substrate, it may not be possible to weld uniformly and well. It can be solved as long as the metal wire or strip is welded in advance.

(4) The following results can be obtained when "no pre-welding", "metal wire or strip without welding":

1 Need to supply solder

2 At the same time as the supply of metal wires or strips, the supply of solder is unstable

3 It is difficult to supply uniform welding materials

This is because the metal wire or strip and the part of the substrate to be soldered are not pre-soldered, so the metal wire or strip and solder must be supplied at the same time. Therefore, it is possible to obtain the result that the solder must be supplied, and the supply of the metal wire or the strip and the supply of the solder make the supply operation unstable and difficult to supply uniform solder material.

Figure 26 is an explanatory diagram showing the ABS-F (Art Beam solar cell technology) of the present invention.

Fig. 26(a) is an explanatory diagram showing the prior art (when the bus/finger electrode is the same step). It shows the prior art of respectively coating (screen printing)/sintering the silver paste (lead-containing glass) on the conventional bus bar 61 and the finger electrode 5 in the same step. After coating and firing, the strip (external terminal) is soldered to the bus bar 61 using a solder material (lead solder) 71.

Figure 26(b) is an explanatory diagram showing the ABS-F technology (when the bus and finger electrodes are different steps). It belongs to the ABS-F technology of the present invention, and shows that the glass paste of the present invention is applied to the fixed strip area 6 (instead of the traditional bus 61) and the silver paste is applied to the finger electrode 5 in different steps. (Leaded glass), followed by simultaneous firing technology. After coating/fired, a soldering material (lead-free solder) 72 is used to solder or ultrasonically solder the strip or wire (external terminal) to the fixing bar 6 (conventional bus 61).

The composition system of the ABS-F technology of the invention of this application

(1) The fixing bar 6 replaces the traditional bus bar 61. The fixing bar 6 is an insulating and light-transmitting film, and is strongly fixed to the nitride film 3 below.

(2) Because the soldering material (lead-free solder) 72 is used to weld external terminals (strips, wires) or ultrasonic welding equipment to fix the fixing bars 6 and finger electrodes 5, the external terminals (strips, wires) While mechanically and firmly fixed to the nitride film 3 and the substrate 1 via the fixing bar 6, external terminals (strips, wires) are directly electrically connected to the upper portion (head) of the finger electrode 5. The following is a detailed description in order.

Fig. 27 is an explanatory diagram showing the advantages/disadvantages of the ABS-F of the present invention.

In Figure 27, the "conventional technology (when the bus bar/finger electrode are the same step)" in the previous paragraph is described.

The characteristics of the prior art are as shown below.

1 Set the silver (lead-containing glass) to the same step on the busbar/finger electrode. That is, as shown in Fig. 26(a), silver (silver paste) of lead-containing glass is applied (screen printing), dried, and fired to the bus bar 61 and the finger electrode 5 at the same time, respectively. Fig. 26(a) generally manufactures the bus bar 61 and the finger electrode 5 in the same step.

2 The silver paste used at this time is tin/lead solder.

In addition, the advantages/disadvantages of the prior art are as illustrated below.

<Advantages>

1 step shortened. Since the bus bar/finger electrode can be manufactured in the same step, the steps can be shortened in comparison with the different manufacturing steps of the present invention described later.

<Disadvantages>

1 Electronic recombination (due to crystal destruction, etc.) due to the influence of lead glass or lead solder on the bus bar. This is because the bus 61 in Figure 26(a) is made by coating/fired with lead-containing silver paste, and the external terminals are soldered to the bus 61 because of the use of lead solder. However, there are disadvantages that the crystal destruction of the part of the silicon substrate 1 close to the bus bar 61 increases the recombination rate of generated electrons and lowers the conversion efficiency of the solar cell.

2 The incident light rate decreases due to the silver in the busbar area. This is because the bus bar 61 in Figure 26(a) is made by coating/fired with lead-containing silver paste, so it completely blocks incident light and blocks this part of the light, resulting in incident The light rate is low.

Next, in Fig. 27, the "ABS-F technology of the present invention (when the bus bar/finger electrode are different steps)" in the next paragraph will be described.

The characteristics of the ABS-F technology of the present invention are as shown below.

1 Set lead-free glass (such as phosphoric acid glass) and finger electrodes in different steps on the fixing strip. That is, as shown in Figure 26(b), the fixed strip 6 after the modification of the conventional bus bar 61 is coated (screen printing) with lead-free glass (such as phosphoric acid glass), and the finger electrode 5 is coated (screen printing). Plate printing) Same as the traditional lead-containing glass silver (silver paste) (different steps). Secondly, they are dried and fired at the same time to manufacture the fixed strip 6 and the finger electrode 5 as shown in Figure 26(b).

2 The fixing strip 6 is lead-free glass (such as phosphate glass)

The finger electrode is lead-containing silver paste.

In addition, the advantages/disadvantages of the present invention are as illustrated below.

<Advantages>

1 Because the fixing strip 6 is made of lead-free materials (such as phosphoric acid glass), the effect of lead-free glass or lead-free solder reduces the recombination of electrons (due to crystal destruction, etc.). This is because the fixing strip 6 in Figure 26(b) is made by coating/firing lead-free glass (such as phosphoric acid glass), and because lead-free solder is used to solder the external terminals to the fixing strip 6, because Under these circumstances, the crystalline destruction of the portion of the silicon substrate 1 close to the fixing bar 6 reduces the recombination of generated electrons and improves the conversion efficiency of the solar cell.

2 Because the part of the fixing strip 6 is made of transparent lead-free material (such as phosphoric acid glass), the light penetrates and the incident light rate is increased. This is because the fixing strip 6 in Fig. 26(b) is made of lead-free material (for example, phosphoric acid glass), so the incident light penetrates and the conversion efficiency is increased due to the degree of penetration. In detail, because the fixing strip 6 in Figure 26(b) allows light to penetrate, and because the penetrated light reaches the lower electron-high concentration area to generate electrons, the corresponding electrons increase, and as a result, it can make The increase in the conversion efficiency of the solar cell corresponds to this increase.

In addition, lead-free solder is used to solder the strip or wire or ultrasonic welding on the fixing bar 6, but even if the width or thickness of the strip or wire at this time is set to about 0.1 to 1 mm according to experiments, it is sufficient The ground takes out electrons (current) to the outside. Therefore, in the fixing strip 6, only the 0.1 to 1 mm width or thickness of the strip or wire cuts off the light, and the rest of the fixing strip 6 penetrates the glass (such as phosphoric acid) of the fixing strip 6 The light after glass) reaches the lower electron high concentration area and is converted into electrons, and the conversion efficiency can be increased to this extent. In the fixing bar 6 (for example, phosphoric acid glass), the light penetrates about 50 to 95% in the range from far infrared (about 1117 nm) to ultraviolet (about 400 nm).

3 Able to reduce silver materials. This is because the fixing strip 6 in Figure 26(b) is from the traditional use of silver The bus 61 is changed, so the corresponding silver material can be reduced.

<Disadvantages>

1 step is slightly increased. This is as described above, because the bus bar 61 made using lead-containing silver paste in Fig. 26(a) is changed to the fixing strip 6 made of lead-free material (for example, phosphoric acid glass) in Fig. 26(b), so The coating of the fixing bar 6 is made of a different material from the finger electrode 5 and a different step, and the corresponding step is slightly increased. The other steps are the same.

In addition, as stated in the remarks column,

‧In the prior art, the individual manufacturing of finger electrodes and bus bars can be observed on the market to gradually increase.

‧In the technology of the present application, since the individual manufacturing of finger electrodes and busbars on the market causes an increase in steps, it can be observed that there is a tendency to emphasize the effect of improving conversion efficiency and reducing silver materials.

Next, with regard to the fixing strip 6 made of the lead-free material (for example, phosphoric acid glass) of the present invention, which has been described in Figs. 26 and 27, the features, structure, and structure are explained in detail using Figs. 28 to 33. Effect etc.

Figure 28 shows a comparative example of the I-V characteristics of each glass of the present invention. This is a comparative example showing the results of manufacturing a glass paste for each glass, using (applying/baking) the fixing strip 6 in the aforementioned Figure 26(b) to manufacture a solar cell, and measuring the I-V characteristics of the solar cell. The horizontal axis represents voltage V, and the vertical axis represents current I.

In Figure 28, the conversion efficiency of phosphoric acid glass solar cells is higher than that of bismuth acid glass, which can be obtained from the outside as shown in the figure. The following selection criteria are set in the experimental department:

(1) The adhesion force of the fixing strip 6 is 5N or more.

(2) Before and after the measurement of the temperature cycle (-20°C to +80°C, 1000 hours), the deterioration of the power generation efficiency and I-v characteristics is within about 0.5%.

(3) The glass does not penetrate the silicon substrate.

As a result, phosphoric acid glass was passed and bismuth acid glass was failed.

In addition, examples of the components of the phosphoric acid glass used here are as follows.

Zinc oxide ZnO 28.00 to 29.00wt%

Phosphorus pentoxide P ₂ O ₅ 49.00 to 50.00wt%

Calcium oxide CaO 13.00 to 14.00wt%

Boron trioxide B ₂ O ₃ 8.00 to 9.00wt%

Additives: alumina Al ₂ O ₃ , silicon oxide SiO ₂ 1wt% or less

Figure 29 shows an example of temperature and humidity changes in the TC 1000 hours of the present invention. It is an example of recording the temperature and humidity changes of each glass in the aforementioned Figure 28 at TC for 1000 hours. The lower part shows an example of temperature change. The low temperature is in the range of 0 to -20°C, and the high temperature is in the range of about 60 to 80°C. The upper part is an example of humidity change when temperature changes.

Figure 30 shows a comparative example of efficiency before and after 1000 hours of TC of the present invention (phosphate glass). Figure 30 is the measurement of the conversion efficiency of the solar cells before and after the measurement at 1000 hours TC in the aforementioned Figure 29 of each sample No. 1 to No. 10. As a result, in the example (No. 1 to No. 5) where phosphoric acid glass was used in the fixing strip 6 (the latter is changed from the conventional busbar) in Fig. 26(b), the conversion efficiency was almost 0.31% or less. The result of the decline.

Figure 31 shows a comparative example of I-V characteristics before and after TC of the phosphate glass of the present invention (No. 1). This is a comparative example showing the I-V characteristics before and after 1000 hours measurement when the phosphoric acid glass of No. 1 in Fig. 30 is used on the fixing strip in Fig. 26(b) for 1000 hours. Result compared to Before the measurement, because the curve after TC 1000 hours has entered the I-V curve, it is considered that the deterioration is caused by the temperature change of severe load, but the maximum is 0.31% or less (refer to Figure 30).

Figure 32 shows a comparative example of EL before and after TC of the present invention (Phosphoric Acid Glass No. 1). (A), (a-1), (a-2), and (a-3) in the upper section are optical photographs showing the whole, and (b), (b-1), (b-2), (b) in the lower section -3) The enlarged view of the upper section is displayed. The phosphoric acid glass system had no unclear images before and after the TC measurement and no expansion was observed, and it was clear that it could be used as a fixing strip 6 for solar cells. On the other hand, although not shown in the figure, in other glasses (such as bismuth acid glass), the longitudinally long rectangular portion in the figure (the part of the fixing strip 6 in Figure 26(b)) is expanded, making it clear that it cannot be use.

Figure 33 shows an SEM observation example of the phosphoric acid glass of the present invention after 1000 hours of TC. Figure 33(a) is a low-power (30-fold) observation example, and Figure 33(b) is a high-power (1000-fold) observation example.

Figure 33(a) is a photograph showing the fixing strips 6 and finger electrodes 5 formed on a silicon substrate. In this photo, the horizontally long rectangle in the lower right part represents the fixing bar 6 in Fig. 26(b), and the photo with the fixing bar 6 enlarged to 1000 times is shown in Fig. 33(b).

Figure 33(c) shows an elemental analysis example of No.1-3 (glass part). This is an example of elemental analysis of the part of each fixing bar 6 for the samples No. 1-3 in Fig. 30, and the Si system of the substrate was not detected. That is, the fixing strip 6 made of phosphoric acid glass, the silicon system of the substrate after the fixing strip 6 is coated/sintered is not detected, and it can be confirmed that silicon has not diffused into the phosphoric acid glass (fixed Article 6).

Figure 33(d) shows an element analysis example of No. 4-9 (Si surface part). This is an example of elemental analysis for the samples No.4-9 in Figure 30, showing the Si part without the fixing bars 6. Only the Si of the substrate was detected, and it was confirmed that other (Zn, P, Ca, B, etc. of phosphate glass) systems were not detected after the measurement at TC for 1000 hours.

Fig. 34 is a diagram showing the configuration of another embodiment of the present invention (a cross-sectional structure without insulating glass, after direct welding). This figure 34 shows that there is no fixing strip 6 (insulation) (not formed) of the aforementioned 2nd figure, and direct welding, or the pre-welded take-out wire (strip or linear wire) is directly welded to the fixing Examples of parts of strips 6 and finger electrodes 5. As shown in FIG. 34, another embodiment is shown in which the welding material 15 is directly welded (ultrasonic welding) to the part of the finger electrode 13 and the nitride film (insulating film) 12.

In Fig. 34, the substrate 11 is a silicon substrate of a solar cell.

The nitride film 12 is an insulating film formed on the substrate 11.

The finger electrode 13 is a well-known one that coats/sinters a silver paste containing lead on the nitride film 12 and opens holes in the nitride film 12 to form an electrical path in the high electron concentration region of the substrate 11.

The welding material 15 is in the direction orthogonal to the finger electrode (finger electrode) 13, and is directly welded to the finger electrode 13 and the nitride film 12 (corresponding to the part of the fixing bar 6 in Figure 2) The strip (or wire) is directly welded, which is equivalent to the bus bar (bus bar electrode).

In accordance with the above, the embodiment shown in Figure 34 is used, by directly welding the finger electrode 13 and the nitride film 12, or the pre-welded strip (wire) directly, Figure 1 to Figure 33 The fixing strip 6 and the like described above become unnecessary, and the structure can be simplified and the cost can be reduced.

Figure 35 is an explanatory diagram showing the transition of the bus bar of the present invention.

Figure 35(a) shows an example of conventional busbar (silver) 14. The bus bar (silver) 14 shown in the figure is to apply silver paste on the nitride film 13 in a direction orthogonal to the finger electrode (silver) 12/ Sintered to form a thread. Therefore, because the bus bar 14 is formed of silver, it has the disadvantage of consuming a large amount of silver.

Figure 35(b) shows an embodiment of the present invention 1 provided with a bus bar (fixed strip) (conductive glass) 141. The bus bar (fixing strip) (conductive glass) 141 shown in the figure is coated/sintered with conductive glass in the direction orthogonal to the finger electrode (silver) 12 without the finger electrode (silver) 12 part. Those formed on the nitride film 13. Therefore, because the bus bar (fixing strip) (conductive glass) 141 is formed of conductive glass, it has the advantage of not requiring silver.

Figure 35(c) shows an embodiment of the present invention 2 provided with a busbar (fixing strip) (insulating glass) 142. The bus bar (fixing strip) (insulating glass) 142 shown in the figure is coated/sintered with the insulating glass in the direction orthogonal to the finger electrode (silver) 12 without the finger electrode (silver) 12 part. Those formed on the nitride film 13. Therefore, because the bus bar (fixing bar) (insulating glass) 142 is formed of insulating glass, it does not require silver, and because of its insulation, it has the advantages of reducing leakage current and improving the efficiency of solar cells.

FIG. 35(d) shows an embodiment in which a welding material (or welding strip) is used to directly weld the finger electrode 12 and the nitride film 13 without using the bus bar of the present invention 3. The welding material (or welding strip) 15 shown in the figure is to directly weld (ultrasonic welding) the welding material (or welding strip) 15 in a direction orthogonal to the finger electrode (silver) 12 on the finger electrode (silver). ) 12 and the nitride film 13 are formed instead of the bus bars 14, 141, and 142. Therefore, the bus bars 14, 141, 142 are not needed, and the steps can be reduced and the cost can be reduced. At the same time, it has the advantage of not requiring a bus bar.

Fig. 36 shows a manufacturing example of the bus bar of the present invention (Fig. 35(d)). Fig. 36 shows the manufacturing example of Fig. 35(d).

Figure 36 (a) shows an example before pre-welding. It is a display bus (welding material (welding rod In the state before the belt) 151 is formed, the finger electrode (silver) 12 is formed in the lateral direction with a width W=100 μm.

Figure 36(b) shows an example after pre-welding. This shows the state after the bus bar (welding material (welding strip)) 151 is formed (after welding material processing), and the bus bar (welding material (welding strip)) 151 is formed in the longitudinal direction with a width W=1 mm. The bus bar 151 is a cross-sectional view as shown in the above-mentioned 35(d). The welding material (welding strip) is welded (ultrasonic welding) in the direction orthogonal to the finger electrode 12 to form (process) a wire with a width of 1 mm. The person. It is clear from the photo shown that the bus bar (welding material (welding strip)) 151 is well welded to the finger electrode 12 and the nitride film 13 with a width of 1 mm.

As described above, in the bus bar (welding material (welding strip)) 151 of the present invention 3 (refer to Figure 35(d)), a welding material with a width of 1 mm is used in the direction orthogonal to the finger electrode 12 to apply The range of the shaped electrode 12 and the nitride film 13 is welded well (ultrasonic welding), and can be formed instead of both the bus bars 14, 141, 142 and the lead-out wire.

Fig. 37 shows an example of the I-V characteristics of the present invention. This is an example of the I-V characteristics of the solar cell shown in Figure 35 (a), (b), (c), and (d). The horizontal axis represents voltage, and the vertical axis represents current.

In Fig. 37, the bus bar area (prior art) is shown in Fig. 35(a) mentioned above.

The busbar area (ABS-F technology) (with/without glass) is shown in Figure 35(b), (c)/(d) above.

As mentioned above, the bus bar area is changed from the traditional (Figure 35 (a)) to the present invention 1 (conductive glass (35 (b)), the present invention 2 (insulating glass (35 (c)), this invention In the case of Invention 3 (without (Figure 35(d))), it is clearly understood that the leakage current can be reduced and any one of them can improve the IV characteristics.

5: Finger electrode (finger electrode)

6: Fixing strip (insulation)

Claims (27)

A solar cell is formed on a substrate with an area that generates high electron concentration when irradiated with light, etc., and an insulating film that transmits light, etc. is formed on the area, and an insulating film is formed on the insulating film to remove electrons from the aforementioned area The extraction port is the finger electrode, and the aforementioned electrons are taken out to the outside through the finger electrode, wherein, A finger electrode containing silver and lead is formed on the insulating film, and the part of the finger electrode or the part with a margin is used as an opening, and an insulating fixing strip is formed on the insulating film and then fired, By the action of silver and lead contained in the finger electrode during the firing, the film under the finger electrode, that is, the insulating film penetrates to form a conductive path between the region and the finger electrode, In addition, during the firing, the insulating fixing strip or the glass material contained in the fixing strip is used to form the insulating fixing strip with good fixation and welding on the insulating film firmly. The solar cell described in the first item of the scope of the patent application, wherein the part with the margin as the opening is a part with a predetermined width that is less affected by the error when the finger electrode and the insulating fixing strip are formed As an opening. The solar cell according to any one of items 1 to 2 in the scope of the patent application, wherein the part with the margin is used as the opening, and the external terminal is ultrasonically welded to the finger electrode and the insulating When the fixing bar is on the contact part with the tip of the ultrasonic soldering iron, there are equal or several narrow openings, so that the contact part of the tip does not directly contact the aforementioned insulating film. The solar cell according to any one of items 1 to 3 in the scope of patent application, wherein the aforementioned firing is based on the temperature at which the finger electrode is calcined and the temperature at which the aforementioned insulating fixing strip is formed Among them, the former is equal to or higher than the latter, and the temperature of the former is used. The solar cell according to any one of items 1 to 4 in the scope of patent application, wherein the firing system is set to 1 second or more and 60 seconds or less. The solar cell according to any one of items 1 to 5 in the scope of patent application, wherein the insulating glass material contained in the insulating fixing strip or the fixing strip is either phosphate glass or bismuth glass the above. The solar cell described in any one of items 1 to 6 of the scope of patent application, wherein the welding material for welding the external terminal to the finger electrode and the insulating fixing strip contains tin, tin oxide, At least one of zinc and zinc oxide. According to the solar cell described in item 7 of the scope of patent application, the soldering material is added with one or more of copper, silver, aluminum, bismuth, indium, antimony, and phosphorus as additives as necessary. The solar cell according to any one of items 1 to 8 in the scope of the patent application, wherein the welding of the external terminal between the finger electrode and the insulating fixing strip is ultrasonic welding. The solar cell described in item 9 of the scope of patent application, wherein the aforementioned external terminal is formed as a strip-shaped strip. The solar cell according to any one of items 1 to 10 in the scope of patent application, wherein the fixing strip is set as an insulating film that penetrates light, and the external terminal of the strip or the wire is welded thereon Or ultrasonic welding, so that the incident light after penetrating the part of the fixing bar will generate the aforementioned high electron concentration area to improve the conversion efficiency, and make the external terminal from welding or ultrasonic welding on the insulating film penetrating the light The leakage current to the substrate is reduced. For the solar cell described in item 11 of the scope of patent application, the aforementioned strip or The width or thickness of the wire is reduced to 0.1mm to 1mm, which increases the light penetration ratio of the part of the fixing bar and improves the conversion efficiency. For example, in the solar cell described in any one of items 1 to 12 in the scope of the patent application, the insulating fixing strip is not formed on the aforementioned insulating film, but is directly welded or the pre-welded take-out wire is welded to the corresponding The formation of the bus-bar electrode or the formation of the bus-bar electrode and the welding of the lead-out wire are performed on the finger-shaped electrode and the finger-shaped electrode and the insulating film in the portion where the fixing bar is not formed. For the solar cell described in item 13 of the scope of patent application, the welding is ultrasonic welding. The solar cell described in any one of items 1 to 14 in the scope of the patent application is formed by forming aluminum or partially perforated aluminum on the aforementioned substrate and provided with the aforementioned regions, insulating films, finger electrodes, and insulating fixing The front side of the strip is the entire opposite back side, and the external terminals on the back side are welded or ultrasonically welded. According to the solar cell described in claim 15, wherein the external terminal on the back side is located at a position on the aluminum on the back side corresponding to approximately the same position as the insulating fixing strip on the front side or on the aluminum Part of the hole is welded or ultrasonically welded to the external terminal on the back side. The solar cell described in any one of items 9 to 16 in the scope of the patent application, wherein the aforementioned external terminal is a take-out wire that takes out the current to the outside of which solder is pre-attached, and the strip or wire is used as a soldering iron tip part While pressing on the substrate or the part of the film formed on the substrate or the fixing strip or the aluminum surface on the back of the substrate or the part of the aluminum surface that has a hole, move the soldering iron tip in the welding direction at a predetermined speed, A soldering iron tip is used to dissolve the solder previously attached to the strip or wire and apply ultrasonic waves, and to remove the attached matter close to the portion, and the molten solder is attached to the portion for soldering. The solar cell described in item 17 of the scope of patent application, wherein the aforementioned wire is a shape obtained by crushing a plurality of round wires. A method for manufacturing a solar cell, the solar cell system is formed on a substrate with an area that generates high electron concentration when irradiated with light, etc., and an insulating film that penetrates the light, etc. is formed on the area, and on the insulating film Where a finger electrode having an extraction port for extracting electrons from the aforementioned area is formed, and the aforementioned electrons are taken out to the outside through the finger electrode, the manufacturing method includes the following steps: Forming a finger electrode containing silver and lead on the aforementioned insulating film, and at the same time forming an insulating fixing strip on the aforementioned insulating film with a part of the finger electrode or a part with a margin as an opening, and then performing a firing step; and By the action of silver and lead contained in the finger electrode during the firing, the film under the finger electrode, that is, the insulating film penetrates to form a conductive path between the area and the finger electrode, In addition, during the firing, the insulating fixing strip or the glass material contained in the fixing strip is used to form a step of firmly fixing and welding the insulating fixing strip on the insulating film. As described in item 19 of the scope of patent application, the solar cell manufacturing method is to form aluminum on the entire backside of the substrate and the front side where the aforementioned regions, insulating films, finger electrodes, and insulating fixing strips are provided. And here, the external terminals are soldered or ultrasonically soldered. The method for manufacturing a solar cell as described in item 20 of the scope of the patent application, wherein the external terminal on the back side corresponds to approximately the same as the insulating fixing strip on the front side A conductive fixing strip is formed and fired at a position or an arbitrary position on the aforementioned aluminum on the back side, and the external terminal on the back side is welded or ultrasonically welded here. The method of manufacturing a solar cell according to any one of the 19th to 21st of the scope of the patent application, wherein the external terminal is a take-out wire that takes out the current to the outside of which solder is pre-attached, and the strip or wire is used with a soldering iron tip While pressing the part of the substrate or the part of the film formed on the substrate or the fixing strip or the aluminum surface on the back of the substrate or the part of the aluminum surface, the soldering iron tip is moved at a predetermined speed in the welding direction, A soldering iron tip is used to dissolve the solder previously attached to the strip or wire and apply ultrasonic waves, and to remove the attached matter close to the portion, and the molten solder is attached to the portion for soldering. According to the method of manufacturing a solar cell described in claim 22, the wire material is a shape obtained by crushing a plurality of round wires. According to the method of manufacturing a solar cell according to any one of items 19 to 23 in the scope of the patent application, the fixing strip is set as an insulating film that penetrates light, and the strip or wire is formed on it. The terminals are welded or ultrasonically welded, so that the incident light after penetrating the part of the fixing bar will generate the aforementioned high electron concentration area to improve the conversion efficiency, and make the insulation film that penetrates the light from welding or ultrasonic welding The leakage current from the external terminals on the upper to the substrate is reduced. For the solar cell manufacturing method described in item 24 of the scope of patent application, wherein the width or thickness of the aforementioned strip or wire is reduced to 0.1mm to 1mm, which increases the light penetration ratio of the fixed strip Conversion efficiency. For example, the method for manufacturing solar cells described in any one of items 19 to 25 in the scope of the patent application does not form an insulating fixing strip on the aforementioned insulating film, but directly solders it Or welding the lead wire with pre-soldering to the finger electrode and the insulating film corresponding to the aforementioned finger electrode and the part where the fixing bar is not formed, to form the bus bar electrode, or to form the bus bar electrode And take out the welding of the wire. As for the manufacturing method of solar cells described in item 26 of the scope of patent application, the welding is ultrasonic welding.

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