TW201836163A - Solar cell and method for manufacturing solar cell - Google Patents

Abstract

The present invention relates to a solar cell and a method for manufacturing solar cell, with an objective of directly soldering a ribbon to a finger electrode on a surface of a silicon substrate 1 to reduce a resistance component and to reduce leakage of electrons, and soldering directly the ribbon to a nitride film to firmly fix it. A solar cell is such configured that a lead wire is soldered with a solder in a direction orthogonal to a finger electrode for extracting electrons from a region formed on an insulating film with a constant width b, over a portion having the finger electrode and a portion of an insulating film having no finger electrode, and electrons from the finger electrode are taken out to the outside by the lead wire and the lead wire is fixed to the substrate.

Description

   Solar cell and manufacturing method of solar cell   

The invention relates to a solar cell and a method for manufacturing a solar cell. A region is formed on a substrate that generates a high electron concentration when irradiated with light and the like, and an insulating film that penetrates with light and the like is formed on the region, and the insulating film is formed on the insulating film. Forming a finger electrode for forming an outlet for taking out electrons from the area, further electrically connecting a plurality of finger electrodes to take out the electrons, and setting a conventional bus electrode as glass or not requiring a conventional bus The electrodes are directly connected to the finger electrodes by solder and directly connected to the solder from the back substrate.

Conventionally, in the design of a solar cell, it is important to efficiently flow electrons generated in the solar cell to an external circuit connected thereto. In order to achieve the above-mentioned object, it is particularly important to reduce the resistance component of the part connected from the battery to the outside, to prevent the generation of electrons from disappearing, and to securely fix external terminals on the front and back.

For example, in the prior art shown in FIG. 12, a nitride film 22 is formed on the surface (upper surface) of the silicon substrate 21, and a net of paste (lead-containing glass) of finger electrodes (silver) 23 is formed on the nitride film 22 The plate is printed and fired to form finger electrodes 23 that have holes in the nitride film 22 as shown in the figure and take out electrons from the high electron concentration region to the outside. Next, screen printing of the bus bar electrode (silver) 24 in a direction perpendicular to the finger electrode 23 is performed, followed by firing. The strip conductor (wire) 25 is soldered on the bus bar electrode (silver) 24 with solder 26 so that the strip conductor 25 is firmly fixed to the silicon substrate 21.

Further, an aluminum electrode 27 is formed on the back surface (lower surface) of the silicon substrate 21, and a strip-shaped wire is soldered and fixed to the aluminum electrode.

When the welding strength of the strip wire 29 is weak when the aluminum electrode 27 is formed on the entire surface, a part of the aluminum electrode 27 is opened in advance (a hole is formed on the surface corresponding to the bus bar electrode 24). Here, screen printing of silver paste and firing are performed to form a silver portion 271, and the strip-shaped wire 29 is fixed to the silver portion with solder 28 to obtain a desired fixing strength.

However, it is necessary to form a bus electrode (silver) 24 on the surface of the conventional silicon substrate 21 described above to collect electrons from a plurality of finger electrodes 23, or to use a bus bar electrode (silver) 24 to make a strip conductor. 25 is firmly soldered to the silicon substrate 21, and the bus electrode (silver) 24 must be made of silver or a paste containing a large amount of silver, and if the paste contains lead glass, there will be a collection of the bus electrode 24 The problem that electrons leak toward the silicon substrate 21 due to firing occurs.

Further, when the aluminum electrode 27 is formed on the entire surface of the silicon substrate 21 and a ribbon wire is soldered to the surface, there is a problem that the ribbon wire cannot be fixed to the silicon substrate 21 with sufficient strength.

In addition, in order to avoid the above problems, as shown in FIG. 12 described above, it is necessary to first make a hole in a part of the aluminum electrode 27, apply silver paste there and burn it, and solder a ribbon wire thereon to obtain sufficient The problem of fixed strength.

The present inventors focused on exposing the upper part of the finger electrodes on the surface of the silicon substrate 1 to the insulating film, and found that the upper part of the exposed finger electrodes was directly soldered as a ribbon wire as an external terminal to reduce the resistance component. In addition, the structure and method of reducing the electron leakage, and enabling the strip-shaped wire to be firmly welded to the nitride film directly or via glass.

In addition, the present inventors have found a structure and a method in which an aluminum electrode or a part of an aluminum electrode is opened in a back surface of a silicon substrate, and the aluminum electrode or a part of the aluminum electrode is directly welded to obtain a sufficient fixed strength.

Therefore, the present invention is to form a region on the substrate that generates a high electron concentration when irradiated with light, etc., and to form an insulating film that can penetrate through light, etc., on the substrate, and to form an insulating film as a way to take out electrons from this region. The finger electrode at the exit is used to take out electrons to the external solar cell through the finger electrode, and the finger electrode having the finger electrode has a width of a certain width b in a direction perpendicular to the finger electrode taking out electrons from a region formed on the insulating film. The part and the part without the insulating film of the finger electrode are soldered to take out the wire, and the electrons from the finger electrode are taken out to the outside by the take-out wire, and the take-out wire is fixed to the substrate.

At this time, when the wire is taken out by soldering with a certain width b in a direction perpendicular to the finger electrode, the width c of the finger electrode portion to be welded is widened or formed in advance to a certain width. c way.

In the case where the wire is taken out with a certain width b in a direction perpendicular to the finger electrode, the interval a between the width c of the enlarged portion of the finger electrode and the width c of the adjacent enlarged portion is set as It is shorter than the length of the tip of the soldering iron to prevent the tip of the soldering iron from directly contacting the insulating film and deteriorating the insulating film.

The welding is performed by ultrasonic welding.

The ultrasonic output intensity using ultrasonic welding is set to an extent that the wire can be taken out and welded, and the output is smaller than the degree to which the insulating film is damaged and the performance is deteriorated.

In addition, in the portion where the take-out line is to be welded by welding, preliminary ultrasonic welding is performed in advance or, as required, preliminary ultrasonic welding is performed.

When preliminary welding is performed on the portion to be welded of the take-out wire, the take-out wire is welded by an ultrasonic method.

In addition, a take-out line to be welded by welding is preliminarily welded.

In addition, the solder contains tin, or tin contains one or more of zinc, copper, and silver.

Therefore, the present invention is to form a region on the substrate that generates a high electron concentration when irradiated with light, etc., and to form an insulating film that can penetrate through light, etc., on the substrate, and to form an insulating film as a way to take out electrons from this region. The finger electrode at the exit is a solar cell that extracts electrons to the outside through the finger electrode and flows electrons from the back surface of the substrate to form a circuit. The solar cell is configured by forming an aluminum electrode on the entire back surface of the substrate or A hole is formed in a part of the aluminum electrode, and a part of the entire surface of the formed aluminum electrode or a part of the hole is formed by soldering a lead wire out to allow electrons to flow in from the back surface of the substrate and fix the lead wire to the substrate.

At this time, a part of the entire surface of the aluminum electrode or a part where a hole is formed is a part corresponding to a take-out line of the surface.

The welding is performed by ultrasonic welding.

In addition, in the portion where the take-out line is to be welded by welding, preliminary ultrasonic welding is performed in advance, or preliminary ultrasonic welding is performed as necessary.

When preliminary welding is performed on the portion to be welded of the take-out wire, the take-out wire is welded by an ultrasonic method.

In addition, a take-out line to be welded by welding is preliminarily welded.

In addition, the welding of the take-out wire is performed in a state in which the temperature of the portion to be welded is lower than the temperature at which the solder is melted and the temperature is higher than the room temperature, and the preliminary heating is performed.

In addition, the solder contains tin, or tin contains one or more of zinc, copper, and silver.

As described above, the present invention focuses on exposing the upper part of the finger electrodes on the surface of the silicon substrate to the insulating film, and directly soldering the upper part of the exposed finger electrodes as a strip wire as an external terminal to reduce the resistance component. In addition, it can reduce the leakage of electrons, and can make the strip-shaped lead wire be firmly welded to the nitride film directly or through the glass, and it becomes a solar cell with high efficiency, which can be taken out and can be firmly fixed.

Moreover, the conventional silver bus bar electrode is not required, and the amount of silver used can be reduced.

Moreover, the steps for forming a conventional silver bus bar electrode are not required, and the number of steps can be reduced.

In addition, the extraction wire (ribbon wire) is directly soldered to the finger electrode and the resistance value is reduced, thereby improving the extraction efficiency of the electrons.

According to the present invention, as described above, a hole is formed in the aluminum electrode or a part of the aluminum electrode on the back surface of the silicon substrate 1, and the aluminum electrode or the portion of the hole of the aluminum electrode is directly welded, thereby reducing the resistance value of the portion where the wire is taken out, and enabling the Fix with sufficient fixing strength.

In addition, compared with the conventional case where a hole is formed on the back of an aluminum electrode to form silver, and a wire is soldered out there, the amount of silver used and the steps of coating and firing of silver can be reduced, and the wire can be firmly fixed.

In addition, the take-out wire (ribbon wire) is directly soldered to the silicon substrate under the aluminum electrode or the hole of the aluminum electrode to reduce the resistance value, so that the inflow efficiency of the electrons can be improved, and a high-efficiency solar cell can be obtained.

1‧‧‧ substrate (silicon substrate)

2‧‧‧nitride film (insulating film)

3‧‧‧ finger electrode

4‧‧‧Bus electrode

5, 9‧‧‧ Ribbon wire (wire, take-out wire)

6, 8, 26, 28‧‧‧ solder

7‧‧‧ aluminum electrode

21‧‧‧ silicon substrate

22‧‧‧nitride film

23‧‧‧ finger electrode

24‧‧‧Bus electrode

25‧‧‧ Ribbon wire (wire)

27‧‧‧Aluminum electrode

29‧‧‧ Ribbon Wire

41‧‧‧Bus area

271‧‧‧Silver part

a‧‧‧ interval

b, c‧‧‧width

FIG. 1 is a configuration diagram of a main part of the present invention.

Fig. 2 is a flowchart (part 1) illustrating the manufacturing method of the present invention.

Fig. 3 is a flowchart (part 2) illustrating the manufacturing method of the present invention.

Fig. 4 is an explanatory diagram (Surface-1) of the present invention.

Fig. 5 is an explanatory diagram (surface-2) of the present invention.

Fig. 6 is an explanatory diagram (back surface-1) of the present invention.

Fig. 7 is an explanatory diagram (No. 1) of the present invention.

Fig. 8 is an explanatory diagram (No. 2) of the present invention.

Fig. 9 is an explanatory diagram (No. 3) of the present invention.

Fig. 10 is an explanatory diagram (No. 4) of the present invention.

Fig. 11 is an explanatory diagram (No. 5) of the present invention.

Fig. 12 is an explanatory diagram of the prior art.

    [Example 1]    

Fig. 1 shows an example of the configuration of the main part of the present invention.

FIG. 1 (a) shows an example of the main part configuration of the so-called ABS technology-0, and FIG. 1 (a-1) shows a detailed example of the main part configuration of the front and back surfaces.

FIG. 1 (b) shows an example of the main part configuration of the so-called ABS technology-1, and FIG. 1 (b-1) shows a detailed example of the main part configuration of the front and back surfaces.

FIG. 1 (c) shows an example of the main part configuration of the so-called ABS technology-2, and FIG. 1 (c-1) shows a detailed example of the main part configuration of the front and back surfaces.

In FIG. 1, the silicon substrate 1 is a substrate (single crystal, polycrystalline) in which silicon of a solar cell is to be formed.

The nitride film (insulating film) 2 is formed on the silicon substrate 1, for example, a high-concentration electron region (a region where a high-concentration electron region is generated when sunlight or the like is irradiated from above) (known) and transparent (sunlight, etc. It is a thin transparent insulating film (conventional) that is firmly formed on a high-concentration electron region.

The finger electrode 3 is screen-printed with a paste containing silver and lead glass on the nitride film 2. The solvent is dried by heating and calcined. The firing phenomenon of lead glass is used to form the nitride film 2 on the lower layer. Those who are electrically connected to the high-concentration electron region take out the electrons generated in the high-concentration electron region from the finger electrode 3 above the nitride film (insulating film) 2 (known).

As shown in FIG. 1 (a), the bus bar electrode 4 is coated with a certain width of glass only in a direction perpendicular to the finger electrode 3 and does not have the finger electrode 3. The solvent is dried by heating and fired. The two are firmly fixed to the nitride film 2. Here, the bus bar electrode 4 does not need to be conductive, as long as it can be firmly fixed to the nitride film 2 and the wire can be soldered out (as described later). For example, in this experiment, a non-conductive ABS paste (vanadium, barium, (tin or zinc or both (or oxides of these)) glass paste) is used.

A ribbon wire (ribbon) 5 is a lead wire soldered directly to the finger electrode 3, and the ribbon wire 5 soldered directly to the finger electrode 3 takes out the electrons generated in the high-concentration electron region to the outside.

The solder 6 is a solder which solders the strip-shaped wire 5 to the finger electrode 3 and the bus bar electrode 4 (FIG. 1 (a)) and the nitride film 2 (FIG. 1 (b), FIG. 1 (c)).

The aluminum electrode 7 is an aluminum electrode formed on the back surface of the silicon substrate 1.

The solder 8 is shown in Figs. 1 (a) and 1 (b). The aluminum electrode 7 formed on the entire back surface of the silicon substrate 1 corresponds to a portion of the strip conductor 5 whose surface is soldered with the solder 6. The back part is soldered with 9 strip wires. In the solder used in the present invention, 8-series tin or zinc is added to a few% to several tens%, and copper or silver may be added to a few tenths to a dozen%. More proportions or other metals can also be added as needed (the same applies hereinafter).

The solder 8 is shown in FIG. 1 (c). The hole portion of the aluminum electrode 7 and a portion of the aluminum portion other than the hole on the aluminum electrode 7 in which a hole is formed on a part of the back surface of the silicon substrate 1 are in a band shape on the surface with the solder 6 A strip-shaped wire 9 is soldered to a back portion corresponding to a portion of the wire 5.

The strip conductor (wire) 9 is an aluminum electrode 7 formed on the back surface of the silicon substrate 1 with a solder 8 and a silicon substrate 1 with an opening portion of the aluminum electrode 7 soldered thereunder to allow electrons to flow in.

The following configurations will be described in detail with reference to Figs. 1 (a-1), (b-1), and (c-1).

Regarding the ABS technology-0 in Figure 1 (a-1):

‧Surface: The surface (surface on the upper side of the silicon substrate 1 in Fig. 1 (a)) is coated with ABS paste on the bus electrode 4 shown in the figure, the solvent is dried by heating and calcined, and the ABS (using vanadate (Salt-based glass that can be soldered) replaces conventional busbar electrodes (silver). In this state, the electrons generated in the high-concentration electron region of the silicon substrate 1 are directly taken out to the outside through the finger electrode 3 through the strip-shaped wire 5 soldered with the solder 6. Therefore, in the path of the conventional photoelectron concentration region-finger electrode 3-silver bus electrode-ribbon wire 5, the portion of the silver bus electrode is omitted, so that electrons can flow directly from the finger electrode 3 to the band wire 5 and Take it to the outside to reduce resistance and loss, and further eliminate the leakage of electrons from the bus electrode in the past.

‧Back surface: The rear surface (the lower surface of the silicon substrate 1 in Fig. 1 (a)) is shown on the aluminum electrode 7 formed on the entire surface of the silicon substrate 1 as shown in the figure. ) 4 is directly soldered to the strip-shaped wire 9.

With the above configuration, the electrons generated in the high-concentration electron region of the silicon substrate 1 can be directly taken out to the outside through the finger electrode 3-the strip conductor 5, and the strip conductor 5 can be connected with the bus electrode (may be It is non-conductive, for example, the corresponding part of ABS paste 4 is directly and firmly soldered to the silicon substrate 1 with solder 6 and fixed. The time for burning the silver paste on the conventional aluminum electrode 7 and soldering the strip conductor on the back surface is omitted, and the strip conductor can be directly soldered on the aluminum electrode 7 and firmly fixed by the present invention.

Regarding ABS Technology-1 in Figure 1 (b-1):

‧Surface: On the surface (surface on the upper side of the silicon substrate 1 in Fig. 1 (b)), the strip-shaped wire 5 shown in the figure is directly soldered to the finger electrode 3 and the nitride film 2 with a certain width b with solder 6 (See Figure 4 etc.). In this state, the electron system generated in the high-concentration electron region of the silicon substrate 1 can be directly taken out to the outside through the finger electrode 3 through the ribbon wire 5 soldered with the solder 6, and the ribbon wire is passed through the nitride film 2. 5 is firmly fixed to the silicon substrate 1. Therefore, the conventional bus electrode is not needed, that is, the electrons can be directly taken out to the outside through the path of the photoelectron concentration region-finger electrode 3 -the strip-shaped wire 5 and the strip-shaped wire 5 can be firmly fixed on the nitride film 2 Silicon substrate 1.

‧Back: Same as the first figure (a-1).

With the above configuration, the electrons generated in the high-concentration electron region of the silicon substrate 1 can be directly taken out to the outside through the finger electrodes 3-the strip conductor 5, and the strip conductor 5 can be firmly secured through the nitride film 2. Fixed on silicon substrate 1. On the back side, as in FIG. 1 (a), the time for burning silver paste on the conventional aluminum electrode 7 and soldering the strip conductor is omitted, and the strip conductor can be directly soldered on the aluminum electrode 7 and firmly fixed by the present invention. .

Regarding ABS Technology-2 in Figure 1 (c-1):

‧Surface: Same as Figure 1 (b-1).

‧Back surface: The back surface (the lower surface of the silicon substrate 1 in Fig. 1 (c)) is provided with holes on the aluminum electrode 7 formed on the silicon substrate 1 as shown in the figure, and corresponds to the portion of the strip conductor 5 on the soldering surface. The strip-shaped wire 9 is soldered to a part of the hole and a part other than the part of the hole. Thereby, the strip-shaped wire 9 can be directly soldered to the silicon substrate 1 with the solder 8 at the portion of the hole, and can be firmly fixed to the silicon substrate 1 to reduce the resistance component.

With the above configuration, the electrons generated in the high-concentration electron region of the silicon substrate 1 can be directly taken out to the outside through the finger electrodes 3-the strip conductor 5, and the strip conductor 5 can be firmly secured through the nitride film 2. Fixed on silicon substrate 1. According to the present invention, the strip-shaped wire 9 can be directly soldered to the silicon substrate 1 with the solder 8 through the hole of the aluminum electrode 7 on the back surface and firmly fixed.

Next, the manufacturing method of the structure of FIG. 1 will be described in detail in the order of FIG. 2 and FIG. 3.

2 and 3 are flowcharts illustrating the manufacturing method of the present invention.

In FIG. 2, S1 is a substrate. This step is described, for example, on the right side, and a P-type single-crystal or poly-crystal silicon substrate 1 is prepared as the silicon substrate 1 of the solar cell in FIG.

The S2 system forms a nitride film. This step is to form a nitride film (insulating film) 2 on the surface of the silicon substrate 1 in the aforementioned first figure. The thickness of the nitride film 2 may be, for example, about 60 to 90 nm.

S3 is coated with aluminum paste on the back. In this step, as described on the right, screen printing and coating of aluminum paste are performed on the back surface of the silicon substrate 1 in FIG. 1. This coating is applied on the entire back surface of Fig. 1 (a-1) and Fig. 1 (b-1). Fig. 1 (c-1) shows a direction perpendicular to the pattern of the finger electrodes 3 on the front surface, and aluminum paste is applied to a portion with or without space on the back surface. A discontinuous strip of aluminum paste is applied (the uncoated portion becomes a non-porous portion of the aluminum electrode 7).

S4 system removes the solvent. In this step, the aluminum paste coated in S3 is dried by heating (for example, heating and drying at 80 ° C. to 120 ° C. for 30 to 60 minutes) to remove the solvent.

S5 is a finger electrode printed on the surface. In this step, screen printing is performed on the nitride film 2 in FIG. 1 using, for example, a paste containing silver and lead glass frit described on the right side.

The S6 system removes the solvent. In this step, the paste applied in S5 is heat-dried (for example, heat-dried at 80 ° C. to 120 ° C. for 30 to 60 minutes), and the solvent is removed.

In Fig. 3, S7 and S8 are performed in the case of Fig. 1 (a). S7 and S8 can be performed simultaneously with printing and solvent removal of the finger electrodes of S5 and S6.

S7 series printed bus electrode. In this step, the bus electrode 4 in FIG. 1 is screen-printed with ABS paste.

S8 is used for solvent removal. The S7 and S8 series use ABS paste (vanadium, barium (tin or zinc or both (or oxides of these))) as shown in Figure 1 (a) to screen-print the bus electrodes and remove the solvent.

S9 series is calcined. In this step, the aluminum electrodes 7 and finger electrodes 3 on the back of the solvent that have been printed in S3 and S4, S5 and S6, and S7 and S8 are removed, and the bus electrodes 4 are further combined as required. Carry out calcination. Alternatively, the calcination may be performed individually. The calcining system is as described on the right side, and for example, it is preferable to perform infrared irradiation in a range of 750 to 820 ° C and 1 second to 60 seconds.

S10 is ultrasonically welded on the surface. In this step, as shown in FIG. 1, the lead-out wire (ribbon wire 5) on the surface is directly soldered to the finger electrode 3. Further, as described above, when preliminary welding (pre-sonic welding or non-ultrasonic preparation welding) is performed in advance on the portion to be welded, non-ultrasonic welding may be performed. In addition, ultrasonic welding (the same applies to welding without ultrasonic waves) is to pre-heat the temperature of the part to be welded (the same is true for the part where welding is possible) to a temperature below which the solder will melt (below the melting temperature and room temperature). By performing the welding in the above state, the solder of the present invention can be reliably welded (the same applies to the ultrasonic welding (no ultrasonic welding) of other parts).

S11 is ultrasonically welded on the back. In this step, as shown in FIG. 1, the take-out wire (the strip-shaped wire 9) is directly soldered to the aluminum electrode 7, or directly to the silicon substrate 1 inside the hole of the aluminum electrode 7. Further, as described above, when preliminary welding (pre-sonic welding or non-ultrasonic preparation welding) is performed in advance on the portion to be welded, non-ultrasonic welding may be performed.

As described above, after the nitride film (insulating film) 2 is formed on the surface of the silicon substrate 1 in FIG. 1, the aluminum paste forming the aluminum electrode 7 is coated on the back surface, the solvent is removed, and the surface of the finger electrode 3 is coated. Fill the silver and lead glass fillers and remove the solvent, apply ABS paste to form the bus electrode 4 and remove the solvent as required, and burn the aluminum electrode 7, finger electrode 3, and bus electrode 4 together as required. As needed, aluminum electrodes 7 on the back, finger electrodes 3 on the front, and bus electrodes 4 on ABS are formed. In addition, both the finger electrodes 3 on the surface and the exposed nitride film 2 are directly soldered to the strip conductor 5 with solder 6 (Fig. 1 (b), Fig. 1 (c)), or between the finger electrodes 3 and Both of the busbar electrodes 4 are directly soldered to the strip-shaped wire 5 with solder 6 (FIG. 1 (a)), and the aluminum electrode 7 and the strip-shaped wire 5 at the back are directly soldered with solder 8 (FIG. 1 (a), 1 (B)), or the strip wire 9 is directly soldered to the silicon substrate 1 with solder 8 through the hole of the aluminum electrode 7, and the strip wire 9 is directly soldered with solder 8 at the non-porous portion of the aluminum electrode 7 (FIG. 1) (c)) This makes it possible to firmly fix the lead wire 9 to the silicon substrate 1 and reduce the resistance from the lead wire 9 to the silicon substrate 1.

Fig. 4 is an explanatory diagram (Surface-1) of the present invention.

Fig. 4 (a) shows an example of a pattern of the finger electrode 3. Fig. 4 (b) shows an enlarged view of Fig. 4 (a).

In FIG. 4, an example of the pattern of the finger electrode 3 is shown in a region (a bus bar region shown in the figure) in which a strip wire 5 having a width b is soldered with solder 6 in a direction perpendicular to the finger electrode 3 in FIG. 1. 41 is the same as the width c. By increasing the width of the finger electrode 3 to the width c, the welding area (contact area) between the strip-shaped wire 5 and the finger electrode 3 can be increased to reduce the contact resistance. On the other hand, if the width c is excessively enlarged, the leakage (recombination) of electrons from the enlarged portion increases and the leakage current tends to increase. Therefore, the optimum value must be determined experimentally.

In addition, as shown in FIG. 4 (b), when welding is performed while the width b (the width of the strip conductor 5) of the bus bar area 41 is enlarged, the distance a between the bus bar area 41 and the adjacent area a It must be shorter than the length of the front end of the ultrasonic soldering iron to prevent the front end of the soldering iron from directly contacting the nitride film 2 below and damaging the nitride film 2. For example, when the length of the tip of the soldering iron is 2 mm, the result of the experiment at an interval a of about 1 mm does not adversely affect the nitride film 2.

Further, when soldering is performed directly, tin and zinc of the soldering material of the base nitride film 2 are tightly adhered to each other, and a bonding force of 5N or more that cannot be obtained with ordinary soldering materials (tin and lead) can be obtained.

Fig. 5 is an explanatory view (surface-2) of the present invention. This figure is an enlarged detailed view showing the surface of the above-mentioned first figures (b) and (c).

In FIG. 5, a nitride film (insulating film) 2 is formed on the surface of a silicon substrate 1, and a pattern of finger electrodes 3 is coated with a paste of silver and lead glass and fired to form the fingers shown in the figure. Shaped electrode 3 (finger electrode 3 having silver inside formed in the opening of the nitride film 2).

In the present invention, while the strip-shaped wire 5 is directly soldered to the protruding finger electrode 3 on the nitride film 2 with solder 6, the strip-shaped wire 5 is soldered to the portion of the nitride film 2 with solder 6. At this time, as shown in FIG. 4 above, the width of the finger electrode 3 is widened (the portion corresponding to the width of the strip conductor 5 is widened), so that the distance between the finger electrode 3 and the solder 6 can be increased. To reduce the contact resistance, and to make the interval smaller than the length of the tip of the soldering iron, so that the tip of the soldering iron does not directly contact the nitride film 2 on the substrate and the nitride film 2 is not affected by damage (see Section 4). Illustration of the figure).

Thereby, the electrons from the high-concentration electron region can be directly taken out to the strip conductor 5 through the finger electrode 3, and the contact resistance between the finger electrode 3 and the strip conductor 5 can be reduced to improve efficiency, and the strip conductor 5 can be improved. The solder 6 is directly soldered to the nitride film 2 and is firmly fixed.

Fig. 6 is an explanatory diagram (back surface-1) of the present invention.

Fig. 6 (a) shows a configuration example of a conventional back surface. Conventionally, an aluminum electrode having a hole formed in a part of a back surface of a silicon substrate was formed, and a silver paste was applied to the portion of the hole and fired to form a silver electrode. A ribbon wire was soldered to the silver electrode with solder (lead solder). Fix the ribbon wire to the silicon substrate with more than specified force.

Fig. 6 (b) shows an example of the direct welding of the present invention.

Fig. 6 (b-1) shows an example in which an aluminum electrode 7 is formed on the entire back surface of the silicon substrate 1, and a ribbon wire 9 is soldered to the aluminum electrode 7 with solder 8 (as shown in Fig. 1 (a) and Fig. 1 ( b) same). In the present invention, the solder wire (tin, zinc) 8 may be used to directly ultrasonically bond the strip-shaped wire 9 to the aluminum electrode 7 with an ultrasonic soldering iron. When preliminary welding of the aluminum electrode 7 is performed, ultrasonic welding can be performed.

Fig. 6 (b-2) shows an example of an aluminum electrode 7 formed with a hole in a part of the back surface of the silicon substrate 1, and the strip lead 9 is soldered to the portion of the hole and the other two portions with solder 8 ( (Same as Fig. 1 (c)). In the present invention, a solder (tin, zinc) 8 may be used to directly ultrasonically bond the strip-shaped wire 9 to the silicon substrate 1 of the hole portion of the aluminum electrode 7 and the aluminum electrode 7 other than the hole using an ultrasonic soldering iron. In addition, during preliminary welding, ultrasonic-free welding can be performed.

Fig. 7 is an explanatory diagram (No. 1) showing the present invention. This figure shows an example of ultrasonic welding conditions.

In Fig. 7, in the above-mentioned Fig. 1 and the like, when the strip wires 5 and 9 are soldered with the solder 6 and 8 to perform ultrasonic welding, if the output of the ultrasonic wave is too strong, the nitrogen of Fig. 1 will be caused. The chemical film 2 is adversely affected by damage and the like, and if the ultrasonic output is too weak, it may happen that the ribbon-shaped wires 5 and 9 cannot be soldered. In order to perform the ultrasonic welding, the optimal ultrasonic output depends on the size of the portion (area) where the finger electrodes 3 are ultrasonically welded. In this experiment, an ultrasonic output of 3W or more deteriorates the device (the nitride film 2 is damaged due to damage, etc.), and 0.5W or less causes soldering failure. In this experiment, a range of 3W or less and 0.5W or more is a more ideal range for performing ultrasonic welding.

Fig. 8 is an explanatory diagram (No. 2) showing the present invention. This figure shows a comparative example of the ABS technology-1 in FIG. 1 (b), the ABS technology-2 in FIG. 1 (c), and the prior art in FIG. 12.

‧ABS technology-1 (Fig. 1 (b)): on the back side, the strip-shaped wire 9 is directly welded to the aluminum electrode 7. On the surface, the lead wire 5 is directly welded to the finger electrode 3 and the lead wire 5 is directly welded to the nitride film 2. Therefore: 1. Although the adhesion on the back is slightly worse than ABS technology-2, it fully meets the specifications; 2. It can reduce the conventional silver; 3. It has good electrical characteristics.

‧ABS technology-2 (Figure 1 (c)): On the back side, the silicon substrate 1 which is under the hole of the aluminum electrode 7 is directly soldered with a strip wire 9 and the aluminum electrode 7 outside the hole is directly soldered. The words on the surface are the same as ABS Technology-1. Therefore: 1. Strong adhesion of the strip-shaped wire on the back; 2. Reduction of conventional silver; 3. Good electrical characteristics.

Prior technology (Figure 12): on the back side, the aluminum electrode 7 is used for forging silver and lead soldering the ribbon wire 9 for lead, or the aluminum electrode 7 is used for forging silver and is connected to the silicon substrate 1 and The lead wire 9 is soldered to the silver lead. On the surface, the lead wire is lead-bonded via the finger electrode 3 and the silver bus electrode. Therefore: 1. A silver bus electrode on the surface is needed; 2. A silver electrode is required on the back.

Fig. 9 is an explanatory diagram (No. 3) showing the present invention.

In FIG. 9, ABS technology-0, ABS technology-1, and ABS technology-2 correspond to ABS technology-0, ABS technology-1, and ABS technology-2 in FIG. 1, respectively.

Types of crystalline polycrystalline and single crystal silicon substrate 1.

V (v) in electrical characteristics is an open voltage of FIG. 10 described later.

I (mA / cm2) in the electrical characteristics is a short-circuit current of FIG. 10 described later.

The FF in the electrical characteristics is the optimum operating point (the point where the maximum power can be obtained) of FIG. 10 described later.

EFF in electrical characteristics is a conversion efficiency represented by the following (Equation 1).

EFF = Jsc × Voc × FF. ． ． ． ． ． (Formula 1)

Ref is a standard value for comparison (standard value of a conventional example). Here, 100 (electrical characteristics), 1 (adhesive force, silver), and 0 (number of manufacturing steps) are set here.

From the experimental results illustrated in Figure 9 above:

‧V (v) (open voltage) in the electrical characteristics is 100.7 to 101.7 in the present invention, which is a slightly larger voltage value.

‧Short-circuit current I is in the range of 100.0 to 101.5, which has sufficient performance compared to Ref.

‧Best operating point FF, ABS technology shows superiority compared to Ref.

‧ In ABS technology, the conversion efficiency EFF shows superiority compared to Ref.

‧The adhesion force of the ribbon wire to the silicon substrate 1 is 2 on the surface, which is twice the standard value. It shows that it is very firmly fixed, and the back is also approximately the same. The case of direct soldering to the silicon substrate 1 in ABS technology-2 is Twice, the display is firmly fixed.

• The amount of silver on the surface is in the range of 0.1 to 0.5 in the present invention, which can be reduced by less than half. Regarding the back side, the present invention can reduce the amount of silver used by 100%.

‧The number of manufacturing steps is based on ABS technology-1 and ABS technology-2 (Figure 1 (b), Figure 1 (c)), which can be reduced by two steps (no need to form a silver bus electrode on the surface (number of steps) -1), and it is not necessary to form a silver electrode on the back surface (the number of steps -1) is reduced by two steps in total).

Fig. 10 is an explanatory diagram (No. 4) showing the present invention. This figure is explained to make it easy to understand the electrical characteristics of the solar cell of FIG. 9. The horizontal axis represents the voltage taken from the solar cell, and the vertical axis represents the current at that time.

In FIG. 10, the open voltage is referred to as Voc (V in FIG. 9).

The short-circuit current is referred to as Jsc (I in FIG. 9), and the optimum operating point FF is the value at the position on the graph where the product of the voltage and current characteristic curves taken from the solar cell is the largest.

The conversion efficiency is a value obtained by the formula Jsc × Voc × FF.

Fig. 11 is an explanatory diagram (No. 5) showing the present invention.

Fig. 11 (a) is an example of a photograph of a front surface and a back surface of a solar cell using ABS glass for the bus electrode of ABS technology-0 in Fig. 1 (a).

Fig. 11 (a-1) shows an example of a photograph of a solar cell in which finger electrodes 3 are formed on the surface in the lateral direction and a bus electrode using ABS glass is formed thereon. ABS glass is formed only on the part without finger electrode 3, and it is displayed on the finger electrode 3 and the part of the bus electrode formed of ABS glass (it is non-conductive, and the ribbon wire can be used with the solder of the present invention) Ultrasonic welding) Photograph of the state where the ribbon wire was welded.

Fig. 11 (a-2) is an example of a photograph showing a state where an aluminum electrode is formed on the entire back surface of Fig. 11 (a-1).

FIG. 11 (b) is an example of a photograph showing a front surface and a back surface of the solar cell of the ABS technology-2 of FIG. 1 (c).

Fig. 11 (b-1) is an example of a photograph showing a state in which the width of a portion of a soldered strip wire is enlarged in the lateral direction of the surface as the finger electrode 3 and the finger electrode 3 (see Fig. 4) is formed. . It is apparent here that the width of the finger electrode 3 of the portion where the longitudinal strip-shaped wire is welded is widened.

FIG. 11 (b-2) shows an example of an aluminum electrode 7 in which a hole is formed in the longitudinal direction of the silicon substrate 1 in which a strip-shaped wire is directly soldered to the base in the longitudinal direction of the back surface.

Fig. 11 (b-3) shows an example of a photograph after the ribbon wire is soldered from above Fig. 11 (b-1) and Fig. 11 (b-2).

The left side of FIG. 11 (b-3) shows an example of a photograph after a strip-shaped wire is longitudinally welded at a part where the width of the finger electrode on the surface of FIG. 11 (b-1) is widened.

The right side of FIG. 11 (b-3) is an example of a photograph showing the longitudinal direction of the aluminum electrode on the back of FIG. 11 (b-2) after the strip-shaped wire is longitudinally welded to the hole (long hole) without aluminum.

Claims (11)

    A solar cell is formed on a substrate by forming a region having a high electron concentration when irradiated with light and the like, and forming an insulating film that penetrates with light and the like on the region. An insulating film is formed on the insulating film to take out electrons from the aforementioned region. A finger electrode with an outlet is used to take out the electrons to the outside through the finger electrode, and the finger electrode having a predetermined width b is provided across the electrode electrode with a certain width b in a direction perpendicular to the finger electrode that extracts electrons from the region formed on the insulating film. A portion of the finger electrode and a portion of the insulating film that does not include the finger electrode are soldered to take out a wire, and the electrons from the finger electrode are taken out to the outside by the take-out wire, and the take-out wire is fixed to the substrate.         The solar cell according to item 1 of the scope of patent application, wherein when the wire is taken out with a certain width b in a direction perpendicular to the finger electrode, the portion of the finger electrode to be soldered is made. The width c is widened, or is formed in advance to the aforementioned predetermined width c.         The solar cell according to any one of claims 1 to 2 of the scope of patent application, wherein when the wire is taken out by soldering with a certain width b in a direction perpendicular to the aforementioned finger electrode, it refers to The interval a between the width c of the enlarged portion of the shaped electrode and the width c of the adjacent enlarged portion is set to be shorter than the length of the tip of the soldering iron to prevent the tip of the soldering iron from directly contacting the insulating film and deteriorating the insulating film.         The solar cell according to any one of claims 1 to 3, wherein the welding is ultrasonic welding.         The solar cell according to item 4 of the scope of the patent application, wherein the ultrasonic output intensity used in the aforementioned ultrasonic welding is set to a level at which the aforementioned take-out line can be welded, and the performance is worse than that of the aforementioned insulating film which is damaged The degree of deterioration is small.         The solar cell according to any one of claims 1 to 5 in the scope of application for a patent, wherein, in the part of the aforementioned take-out line to be welded by the aforementioned welding, ultrasonic-free preliminary welding is performed in advance, or ultrasonography is performed as required. Sonic ready for welding.         The solar cell according to item 6 of the scope of application for a patent, wherein, in a case where the preliminary welding is performed on a part to be welded of the take-out line, the take-out line is welded in an ultrasonic-free manner.         The solar cell according to any one of claims 1 to 7 in the scope of the patent application, wherein the take-out wire to be welded by the aforementioned welding is preliminarily welded.         The solar cell according to any one of claims 1 to 8 in the scope of patent application, wherein the welding of the take-out line is performed so that the temperature of the portion to be welded is lower than the temperature at which the solder will melt and higher than room temperature. Welding is performed in a preheated state.         The solar cell according to any one of claims 1 to 9 in the scope of patent application, wherein the solder contains tin or tin contains one or more of zinc, copper, and silver.         A method for manufacturing a solar cell. The solar cell is formed on a substrate with a region having a high electron concentration when irradiated with light and the like, and an insulating film that penetrates with light and the like is formed on the region, and is formed on the insulating film as A finger electrode for taking out an electron from the aforementioned region, and taking the aforementioned electrons to the outside via the finger electrode. The manufacturing method of the solar cell is a finger electrode for extracting electrons from the aforementioned region formed on the insulating film. The vertical direction covers a portion having the aforementioned finger electrode and a portion having the aforementioned insulating film without the aforementioned finger electrode with a certain width b. The wire is taken out by soldering, and the electrons from the aforementioned finger electrode are taken out to the outside by the extraction line. The extraction line is fixed to the substrate.