JP2002057354A - Photovoltaic element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic element easy to mass produce, and to provide its manufacturing method for improving energy efficiency of a solar battery module, by facilitating reduction of connection resistance between a metal fine wire and a metal electrode. SOLUTION: A method for manufacturing a photovoltaic element made of at least a photovoltaic layer, a metal fine wire 102 coated with a conductive resin 111, and a metal electrode 103 includes a first step for removing the conductive resin 111 from the surface of the metal fine wire 102, a second step for removing the oxide film on the surface and the remaining conductive resin from the metal fine wire 102, and a third step for joining the metal electrode 103 and the conductive resin removed part of the metal fine wire 102 with solder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic element such as a solar cell and a method for manufacturing the same, and more particularly to a photovoltaic element having an improved method for joining a metal wire and a metal electrode, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, attention has been paid to photovoltaic power generation, and the need for a photovoltaic element having a larger area and lower cost has been increasing.

Generally, in a photovoltaic layer forming a photovoltaic element, the resistivity of the charges in the photovoltaic layer to the movement in the element surface direction is high. Therefore, in the case of a photovoltaic element having a large area, an electrode having a high conductivity made of metal is formed on the surface of the photovoltaic element in order to reduce Joule loss due to movement of electric charges in the element surface direction.

When the electrode is on the light incident side, the electrode made of metal is generally opaque, and is formed so as not to block incident light as much as possible. Conversely, when the electrode is on the anti-light incident side, the electrode may be formed on the entire surface, but may be formed on the minimum necessary part for cost reduction.

For example, as shown in FIG. 6A, an electrode 601 formed on a comb tooth on a light incident surface or a back surface is known.
In the case of the light incident surface, the comb-teeth electrode in which the metal wire electrodes are formed at regular intervals as described above can efficiently collect electric charges by suppressing Joule loss without interrupting incident light as much as possible. is there. In addition, in the case of the back surface, the electrode forming material can be reduced, so that it can be formed at lower cost.

However, such an electrode manufacturing method is shown in FIG.
As shown in (b), the conductive resin 602 is screen-printed and baked, and then the solder paste 601 is printed thereon and reflowed. Therefore, it is difficult to increase the thickness of the electrode, and a sufficient Joule loss reduction effect cannot be obtained when the photovoltaic element has a larger area.

Therefore, as shown in FIG. 7, a comb-shaped electrode using a thin metal wire 702 and a metal electrode 703 capable of easily increasing the thickness of the electrode has been devised. FIG. 7 shows a thin metal wire 702 having a conductive resin coating 711 as a metal electrode 70.
The projection is attached to the projection 3 by being wrapped around the projection and deformed by pressing, and then heated and thermocompression-bonded to the surface of the photovoltaic element. Japanese Patent Application Laid-Open No. 9-36395 discloses the details thereof.

[0008]

By the way, in the conventional comb-shaped electrode using a metal thin wire and a metal electrode having a conductive resin coating, the connection resistance can be easily reduced by the interposition of the conductive resin coating. Was not. Therefore, there is a problem that the energy conversion efficiency of the solar cell module is reduced.

SUMMARY OF THE INVENTION In view of the above problems, the present invention makes it possible to easily reduce the connection resistance between a thin metal wire and a metal electrode, to improve the energy conversion efficiency of a solar cell module, and to improve the mass productivity of light. An object is to provide an electromotive element and a method for manufacturing the same.

[0010]

Means for Solving the Problems In order to solve the above problems,
The method for manufacturing a photovoltaic element of the present invention is a method for manufacturing a photovoltaic element comprising at least a photovoltaic layer, a thin metal wire covered with a conductive resin, and a metal electrode. A first step of removing the conductive resin from the surface, a second step of removing the oxide film and the conductive resin residue on the surface of the fine metal wire, and a conductive resin removing portion of the fine metal wire and the metal electrode; And a third step of joining with a brazing material.

In the method of manufacturing a photovoltaic element, it is preferable that the first step is performed by irradiating the conductive resin with a Q-switch modulated YAG laser beam by a rotating mirror or a rotating prism.

It is preferable that the conductive resin contains a substance having a high energy absorption of laser light.

It is preferable that the substance having a high laser beam energy absorption rate is carbon black or graphite.

In the second step, ultraviolet light,
It is preferable to use microwave plasma treatment, ozone treatment, corona treatment, electron beam irradiation treatment or gamma ray treatment.

Further, as the second step, it is preferable to use an aqueous peroxide solution or an acidic solution alone or in combination.

In the third step, a brazing material is formed on the surface of the metal electrode or the surface of the thin metal wire from which the conductive resin coating has been removed, and the metal electrode and the thin metal wire are heated and pressed to form a brazing material. It is preferable to perform metal bonding.

It is preferable to use resistance heating as a method for heating the brazing material.

In this resistance heating, it is preferable to have a heater section and a heater cooling section.

On the other hand, the photovoltaic device of the present invention is manufactured by any one of the above methods.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

Hereinafter, each constituent material used in the method for manufacturing a photovoltaic element of the present invention will be described. (Photovoltaic layer) amorphous silicon, microcrystalline silicon,
Any of thin film single crystal silicon, polycrystalline silicon, single crystal silicon, and a compound semiconductor other than silicon may be selected. Further, it is possible to have an arbitrary junction structure such as a pn junction, a pin junction, and a Schottky type.

When the photovoltaic layer is a thin film, it may have a substrate for supporting it. As a typical board,
A glass substrate on the light incident side and a metal substrate on the opposite incident side may be used.

Further, a back reflector for reflecting transmitted light may be provided below the photovoltaic layer. As the back reflector, a back reflector obtained by depositing a layer of zinc oxide on a metal layer having a high light reflectance such as aluminum or silver is known. Further, the surface of the back reflector or the photovoltaic layer may be subjected to a treatment for forming irregularities.

However, according to the present invention, when a photovoltaic element is formed and a solar cell module is formed, the stress applied to the fine metal wires on the photovoltaic layer and the residual stress after that, and the wind generated when the module is installed in an external environment. Since the module is also intended to improve the resistance to the stress applied to the thin metal wire by bending the module due to snow or the like, the more the photovoltaic layer has flexibility and the larger the area, The effect is great.

(Fine metal wire) The material of the fine metal wire is copper, aluminum, gold, platinum, silver, lead, tin, iron, nickel, cobalt,
Any configuration may be used as long as the main component is a metal such as zinc, titanium, molybdenum, tungsten, and bismuth. Further, the above materials may be combined in multiple layers. The shape of the thin metal wire may be a circle, an ellipse, a triangle, a quadrangle, or another polygon.

However, the thin metal wire is for guiding the electric power generated in the photovoltaic layer to the metal electrode. Therefore, in order to prevent power loss, low resistance is desired. Therefore, it is preferable to select from copper, gold, silver, lead, and tin. Further, it is desirable that the cross-sectional area and shape of the thin metal wire be determined so that the sum of the Joule loss in the thin wire and the loss caused by the thin wire blocking light incident on the photovoltaic layer is minimized. Generally, an area of 80 to 200
Those having a ratio of about 00 μm 2 and a ratio of the cross section of the photovoltaic element surface direction to the normal direction and an aspect ratio close to 1 are preferably used.

It is known that the bonding between the surface of the photovoltaic layer and the fine metal wire is made of a conductive resin. As the conductive resin, a resin in which fine metal particles such as silver and copper are dispersed in the resin is generally used. In particular, when a large-sized thin-film photovoltaic layer is used, those containing carbon fine particles and metal oxide fine particles such as indium tin oxide, tin oxide, and titanium oxide are preferably used. This is because it is difficult to form a photovoltaic layer uniformly over a large area, and therefore, it often has a defective portion where the positive electrode and the negative electrode are short-circuited. For this reason, it is effective to interpose a conductive resin having an appropriate resistivity therebetween so as not to lower the element characteristics so that the low-resistance thin metal wire does not directly contact the short-circuit defect portion. is there.

(Conductive Resin) As the conductive resin, a resin paste in which conductive fine particles made of carbon or metal oxide are dispersed is preferably used. The conductive resin may be thermosetting or thermoplastic. For example, epoxy resin, urethane resin, butyral resin, phenol resin,
Melamine resin, alkyd resin, polyester resin, polyimide resin, fluororesin, silicone resin, phenoxy resin and the like can be mentioned.

The conductive resin coating may be a multilayer. When the thin metal wire is in direct contact with the photovoltaic element, metal ions may diffuse into the photovoltaic layer and deteriorate the element performance. It is known to form a conductive resin layer as a metal ion block layer in order to prevent such a situation. In this case, a thermosetting conductive resin is used, and is heated and completely cured during coating. Outside the block layer, a semi-cured conductive resin coating is formed as an adhesive layer. The metal wire with the conductive resin coating thus completed is placed on the photovoltaic element, and is fixed by semi-cured conductive resin when pressure and heat are applied. Such methods are known.

(Method of Forming Conductive Resin Coating on Thin Metal Wire) The conductive resin of the conductive resin coating is as described above.
As a method for forming a conductive resin coating on a thin metal wire, a method using a dispenser, a brush, a spray, a roll coater, or the like is known.

(Metal electrode) The material of the metal electrode is copper, aluminum, gold, silver, lead, tin, iron, nickel, cobalt, zinc,
Any configuration may be used as long as the main component is a metal such as titanium, molybdenum, tungsten, and bismuth.
Further, the above materials may be combined in multiple layers. The cross section of the metal electrode is circular, elliptical, triangular,
It may be a rectangle or other polygons.

However, the metal electrode is for further guiding the electric power guided by the thin metal wire to the outside of the photovoltaic element. Therefore, in order to prevent power loss, low resistance is desired. Therefore, it is preferable to select from copper, gold, silver, lead, and tin. The thickness, width, and shape of the cross section of the metal electrode are preferably selected so that the Joule loss due to the current flowing through the electrode is sufficiently smaller than the power generation of the photovoltaic element. Most commonly, a metal foil material having a thickness of about 10 to 500 μm is formed and used in a width of about 1 to 30 mm.

An embodiment of the method for manufacturing a photovoltaic device according to the present invention will be described below.

(First Step of Removing Conductive Resin from the Surface of Fine Metal Wire) The present invention does not lose its effect depending on the type of the step of removing the conductive resin coating by irradiating a laser beam. By using a laser, it is easily possible to very selectively remove only the conductive resin coating from the surface of the fine metal wire.

Other than laser peeling, there are known methods of applying a chemical agent and shaving with a sandpaper, a wire brush, a cutter, or the like. However, these methods are not as selective as removal by a laser and may damage fine metal wires. Effect. Therefore, the thin metal is easily broken.

Further, by scanning with a laser, it is possible to easily form a peeled portion arbitrarily from a very small area to a large area as compared with other methods.

As the type of laser, any laser can be used as long as it has the effect of converting the energy of the laser beam into thermal energy in the conductive resin coating and cutting the chain of the conductive resin coating. Generally, a carbon dioxide laser, a YAG laser, and an excimer laser are most preferably used.

However, the carbon dioxide laser and the excimer laser require a large-sized apparatus and complicated maintenance.
YAG lasers are most preferred because they are more expensive.

Further, it is preferable to apply Q-switch modulation to the YAG laser beam to shorten the pulse width and increase the pulse peak value at the same time. By doing so, the effect of heat is less likely to be transmitted to the thin metal wires, and the selectivity of removing only the coating is increased. In some cases, it is also effective to appropriately defocus.

As a scanning method of the laser beam, a galvanometer using a rotating mirror or a rotating prism is preferable at a very high speed, and is very simple. When the path for guiding the laser light is a fixed optical system, the spot diameter of the laser light can be made smaller, and the energy density at the pulse peak becomes higher. Therefore, the selectivity is further increased.

The inclusion of a substance having a high energy absorption of laser light, such as carbon black or graphite, in the conductive resin coating has the effect of increasing the selectivity of peeling.

Further, when a laser reflector is provided on the side of the thin metal wire opposite to the laser emitting unit and radiated, it is effective to strip the entire circumference of the thin metal wire. As the reflector, a metal body having a high reflectance or a metal film deposited on glass is generally used.

(Second Step of Removing Oxide Film or Residual Resin on the Surface of Fine Metal Wire) The present invention lacks its effect depending on the type of the step of removing the oxide film and resin residue on the surface of the fine metal wire. There is no.

The method for removing the oxide film and the resin removal residue on the surface of the fine metal wire is a method using ultraviolet light, microwave plasma treatment, ozone treatment, corona treatment, electron beam irradiation treatment or gamma ray treatment as a dry process. As a wet process, a method using an acidic solution such as sulfuric acid, nitric acid or hydrochloric acid, or a peroxide solution such as a hydrogen peroxide solution or a peracetic acid solution is known, and it is more effective to combine them.

(Third Step of Joining Conductive Resin Removal Portion of Fine Metal Wire and Metal Electrode with Brazing Material) The present invention provides a process of joining the conducting resin removal portion of fine metal wire and metal electrode with a brazing material. Depending on the type, the effect is not missing.

As an electrical bonding structure that is stable for a relatively long time even in a severe external environment required for a photovoltaic element, a bonding structure in which a brazing material is interposed between a thin metal wire and a metal electrode is known. These manufacturing methods include forming a brazing material layer on at least one of the metal fine wire and the metal electrode in advance, or removing the conductive resin coating of the metal fine wire by laser, and forming an oxide film or a conductive resin on the surface of the exposed metal fine wire. After removing the remainder and placing a creamy or chip-shaped brazing material on the exposed metal, the surfaces of the fine metal wires and the metal electrodes are aligned, and the surfaces are joined by applying pressure and heat.

In the present invention, a method having high mass productivity includes:
It is effective to form a brazing material layer on at least one of the thin metal wire and the metal electrode in advance and apply pressure and heat. As a method of forming a brazing material on the surface of a metal electrode or a thin metal wire, electrolytic plating, electroless plating, and a printing method are known.

The brazing material on the metal surface for bonding is, for example, S
n-Pb system, Bi-Sn system, Sn-Ag system, Sn-Sb
System, binary system such as Pb-Ag system, Sn-Pb-Bi system, S
A ternary system such as an n-Pb-Ag system and a Pb-Ag-Sn system may be used. Thickness is 1 to 20 depending on bondability and cost.
About μm is good.

As a method for heating the metal electrode, resistance heating is known, and a resistance heating method having a heater section and a heater cooling section is particularly effective in the production thereof. Because, in this method of heating and joining via the above brazing material, heat is transferred quickly when the metal thin wire and metal electrode are pressed,
It is important and effective to liquefy the brazing material, make it compatible, and cool it while keeping it fast.

The present invention is based on a low resistance heating method and has a heater section and a heater cooling section to enable rapid heating and rapid cooling. The heater unit according to the present invention includes W, Mo,
A metal such as SUS or an alloy thereof is used as the high-resistance material, and the cooling unit is water-cooled or air-cooled, or a method in which a metal having a small specific heat and a large heat capacity is brought into contact.

FIG. 4 is a schematic view showing an example of a photovoltaic element manufactured by the method for manufacturing a photovoltaic element according to the present invention. In FIG. 4, 501 is a photovoltaic layer, 502 is a thin metal wire, 503 is a metal electrode, 504 is an electrical junction, 50
Reference numeral 5 denotes a conductive resin joint, and 511 denotes a conductive resin coating.

As shown in FIG. 4, a method in which the conductive resin coating 511 applied to the entire thin metal wire 502 is peeled off only where the electrical joint 504 is formed is a very simple manufacturing method and is effective.

[0053]

EXAMPLES The method of manufacturing a photovoltaic device according to the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 As Example 1 of the present invention, a photovoltaic element shown in FIG. 1 was manufactured. A copper wire having a diameter of 4 to 5 mm was prepared as a material of the metal thin wire 102, and a copper thin wire having a diameter of 100 µm was produced by a wire drawing device. This thin copper wire was continuously produced and wound on a bobbin in an amount of 500 g.

Next, a conductive resin layer 111 was applied and formed using a roll coater for enameled wires. The conductive resin layer is an inner layer 111a for blocking movement of metal ions.
And a thin metal wire having an outer layer 111b for bonding and fixing on the photovoltaic layer and the metal electrode.

First, the copper fine wire was unwound from the bobbin, and the oil on the surface was removed with acetone. Next, the felt was continuously passed through a treatment tank in which the conductive resin for the inner layer was contained. This inner layer conductive resin contains 33 parts by weight of carbon black,
6.4 parts by weight of a butyral resin, 4.2 parts by weight of a cresol resin, a phenol resin, an aromatic hydrocarbon resin, 18 parts by weight of a diol isocyanate as a curing agent, 18 parts by weight of xylene as a solvent, 12 parts by weight of diethylene glycol monomethyl ether, 3.6 parts by weight of cyclohexanone and 0.7 parts by weight of γ-mercaptopropyltrimethoxysilane as a coupling agent were mixed and dispersed using a paint shaker. After the application, unnecessary conductive resin was dropped using a dice, and completely cured through a drying oven. At this time, the thickness of the inner conductive resin layer was adjusted to 5 μm by adjusting the wire feed speed and the diameter of the die. Next, it passed through a treatment tank in which a felt containing an outer layer conductive resin was arranged in the same manner. This outer layer conductive resin is made of carbon black
5 parts by weight, 41 parts by weight of urethane resin, phenoxy resin 1
4 parts by weight, 6 parts by weight of hydrogenated diphenylmethane diisocyanate as a curing agent, 4 parts by weight of an aromatic solvent as a solvent, and 0.7 parts by weight of γ-mercaptopropyltrimethoxysilane as a coupling agent were mixed and dispersed by a paint shaker. Produced. After the application, unnecessary conductive resin was dropped using a die, semi-cured through a drying oven, and wound around a reel bobbin. At this time, the thickness of the outer conductive resin layer was adjusted to 25 μm by adjusting the wire feeding speed and the diameter of the die.
And

Thus, a thin copper wire covered with the conductive resin layer was prepared. When the thin metal wire on which the conductive resin layer was formed was sampled and the cross section and the surface were observed using SEM, a uniform conductive resin layer without pinholes was formed.

Next, a photovoltaic layer 101 was formed. Width 3
An Al layer having a thickness of 2000 ° was formed on a stainless steel substrate having a thickness of 150 μm wound on a roll of 6 cm by a roll-to-roll method using a sputtering apparatus. In the same manner, a lower electrode made of ZnO having a thickness of 1 μm is formed, and thereafter, placed in a microwave plasma CVD film forming apparatus, and a bottom n layer / i layer / p layer 101a, a middle n layer / i layer / p layer 101b, An amorphous silicon layer of the top n layer / i layer / p layer 101c was deposited to form a triple photovoltaic layer.

Next, an ITO film was formed on the photovoltaic layer by a sputtering method as the transparent electrode layer 106 having a function of preventing reflection (film formation temperature: 450 ° C., film thickness: 700 Å).

Next, the obtained stainless steel substrate with a photovoltaic layer was divided into a length of 24 cm to produce a substrate of 36 cm × 24 cm. The width of the transparent electrode layer near the outer periphery of the substrate is 1 m.
m. The removal method employed was an electric field etching method in which the substrate was immersed in a sulfuric acid solution and an electric field was applied between the substrate and the counter electrode.

Next, as shown in FIG. 2, the thin metal wires obtained above were laid in the air using a laying machine. Next, a concave reflecting plate 214 made of silver-coated glass is arranged on the opposite side of the laser emitting unit with respect to the thin metal wire, and YA
By irradiating the G laser beam 215, the conductive resin coating was placed 1.5 mm from the end of the metal electrode to be placed next.
, And the remaining area was peeled off all around. The laser light used was a Q-switch modulated YAG laser light, which was irradiated from above onto the laser scan area 216 in FIG. Only the conductive resin coating was selectively removed. The laser irradiation condition is output 10W (measured with thermopile type probe),
The pulse frequency is 50 kHz, the pulse width is several nanoseconds, the scanning speed is 2000 mm / sec, and the spot diameter is about 100.
μm and 15 mm defocus.

Next, oxygen plasma treatment is performed on the removed portion.
40 Wmin / m in the presence of oxygen gas ^TwoEnergy
After processing for 5 minutes while generating plasma, the removal part is replaced with S
When analyzed with the EM X-ray analyzer, the copper surface was found in places.
No resin coating was exposed and remained.

Next, as shown in FIG. 1, a double-sided tape 110 (substrate PET 50 μm) was formed on both ends of the substrate on which the photovoltaic layer was formed.
m, silicone glue, length 24 cm, width 7 mm), and a metal electrode 103 thereon having a width of 5 mm and a length of 24 mm.
20 cm of 6: 4 solder on copper foil of 100 μm thickness
A μm-plated one was attached.

Next, the above-described fine metal wire and the surface of the photovoltaic element were bonded. The bonding method is as follows. The above-mentioned laid thin metal wire and the substrate are arranged such that the coating of the thin metal wire (residual portion 1.5 mm) overlaps the metal electrode as shown in FIG. The mixture was heated at a temperature of 5 ° C for 5 minutes and 30 seconds, taken out of the dryer while holding it, and air-cooled for 4 minutes and 30 seconds, and then the holding part was removed. Thereby, the above-mentioned semi-cured outer layer resin coating is completely cured and adhered. At this time, a resin bonding portion and a brazing material bonding portion between the thin metal wire and the metal electrode are also formed by the same principle.

Next, the junction resistance between the thin metal wire and the metal electrode was set to 4
When measured by the terminal method, n = 100 and 0.01Ω for all
/ Book or less.

As described above, it was possible to manufacture the minimum necessary electric connection part very easily by the present invention.

Furthermore, the anode take-out part 112 and the cathode take-out part 113 were connected by soldering, and 100 photovoltaic elements having a 36 cm × 24 cm square cell configuration were manufactured. The initial characteristics of the manufactured photovoltaic element were measured as follows.

First, voltage-current characteristics in a dark state were measured.
When the shunt resistance was determined from the inclination near the origin, the average was 200 kΩ · cm ² , and no shunt occurred.

Next, the solar cell characteristics were measured using a simulated solar light source (manufactured by SPIRE) having a light intensity of 100 mW / cm ^{2 in} the AM1.5 global sunlight spectrum.
The conversion efficiency was found to be good at 9.0% ± 0.2%, with little variation. The yield was 98%.

In order to examine the stress resistance of these photovoltaic elements, a test was conducted in which bending with a radius of curvature of 2 m was repeatedly applied vertically. The test conditions were 5 seconds per repetition and 10,000 repetitions. When the photovoltaic element after the test was measured with a simulator in the same manner as in the initial stage, no significant difference was found in the initial conversion efficiency with an average deterioration of 1.0%.

Further, these photovoltaic elements were placed on a galvalume steel plate having a thickness of 0.4 mm by a known method (460 mm thick).
μm EVA, photovoltaic element, 460 μm thick EVA
And a module is laminated by vacuum degassing and heating), and the reliability test is performed by a temperature-humidity cycle test A- specified in the environmental test method and the durability test method of the crystalline solar cell module of Japanese Industrial Standard C8917. 2 was performed.

That is, the sample is put into a thermo-hygrostat capable of controlling the temperature and humidity, and the temperature is changed from −40 ° C. to + 85 ° C. (relative humidity 85%).
%) Was repeated 20 times. Next, the photovoltaic element after the test was measured by a simulator in the same manner as in the initial stage. As a result, the initial conversion efficiency was 2.0% on average, and no significant degradation occurred.

Finally, in order to examine the stress resistance of these solar cell modules, a test was conducted in which bending with a polar radius of 2 m was repeatedly applied vertically. The test conditions were 5 seconds per repetition and 10,000 repetitions. When the photovoltaic element after the test was measured with a simulator in the same manner as in the initial stage, no significant difference was found in the initial conversion efficiency with an average deterioration of 3.0%.

This example shows that the photovoltaic element manufactured by the manufacturing method of the present invention has excellent characteristics and high reliability.

Comparative Example 1 The present example is different from Example 1 only in that the plasma treatment was not performed after the removal of the coating resin for the fine metal wires.

After bonding the thin metal wire and the metal electrode and heating,
When the junction resistance between the thin metal wire and the metal electrode was measured with n = 100 pieces, 0.01 Ω / piece or less was 10% and the remaining 90% was 90Ω.
% Was 1 to 5 Ω / piece. For this reason, when the portion removed by the laser was observed by SEM, resin was observed in some places, and it was found that the wettability of 6: 4 solder was poor and the bonding was poor.

[Embodiment 2] This embodiment is different from Embodiment 1 only in the method of heating and joining by using a resistance heating means 319 having a heater 317 and a heater cooling section 318 as shown in FIG. . FIG. 5A shows the results of measuring the thermal profile of the resistance heating unit and the thermal profile in the first embodiment. The measurement was performed by attaching a sensor to a thin metal wire. In addition, a reflow soldering device manufactured by Himax Co., Ltd. was used. As can be seen in FIG. 5 (b), the time required for joining was greatly reduced.

[Embodiment 3] This embodiment is different from Embodiment 1 only in that an acid treatment is performed after the plasma treatment. The present embodiment is characterized in that the plasma treatment and the 10% Vol hydrochloric acid are used in combination with acid cleaning for 5 minutes, and the effect is as follows. The bonding strength between the electrodes was compared. Table 1 shows the results.

[0079]

[Table 1]

The bonding force shows a maximum value from the minimum value of the number of bonded parts n = 100, and is performed by a tensile force in the direction of 0 °, and HEIDON-14 manufactured by Shinto Kagaku Co., Ltd. was used. As shown in Table 1, the bonding strength was increased by performing the acid treatment.

[0081]

As described above, according to the present invention,
To facilitate the reduction of the connection resistance between the thin metal wire and the metal electrode, to improve the energy conversion efficiency of the solar cell module, and to more easily manufacture a photovoltaic element using the thin metal wire. And excellent mass productivity.

[Brief description of the drawings]

FIG. 1 shows a photovoltaic element of Example 1, and FIG.
Is a plan view thereof, (b) is an arrow view showing a cross section taken along line AA,
(C) is an arrow view showing a cross section taken along line BB.

FIGS. 2A and 2B show a manufacturing process of the photovoltaic element of Example 1, in which FIG. 2A is a plan view and FIG. 2B is an arrow view showing a cross section taken along line AA.

FIG. 3 shows an apparatus used in Example 2;
Is a front view thereof, and (b) is a side view thereof.

4A and 4B show examples of a photovoltaic element manufactured by the method for manufacturing a photovoltaic element according to the present invention, wherein FIG. 4A is a schematic view, and FIG. 4B is an arrow showing a cross section taken along line AA. FIG.

FIG. 5 is a diagram showing a thermal profile of the present invention;
(A) is a thermal profile of Example 1, (b) is Example 2
FIG.

FIG. 6 shows an example of a conventional photovoltaic element,
(A) is a plan view thereof, and (b) is an arrow view showing a cross section taken along line AA.

FIG. 7 shows another example of a conventional photovoltaic element.
(A) is a plan view thereof, and (b) is an arrow view showing a cross section taken along line AA.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Photovoltaic layer 101a Bottom pin layer 101b Middle pin layer 101c Top pin layer 102 Fine metal wire 103 Metal electrode 103a Copper foil 103b 6: 4 solder 104 Electrical joint 105 Conductive resin joint 106 Transparent electrode layer 107 Stainless steel substrate Reference Signs List 108 Al layer 109 Zinc oxide layer 110 Double-sided tape 111 Conductive resin layer 111a Inner layer conductive resin coating 111b Outer layer conductive resin coating 112 Anode extraction section 113 Cathode extraction section 202 Fine metal wire 211a Inner layer conductive resin coating 211b Outer layer conductive resin coating 214 Reflector 215 Laser light 216 Laser scan area 317 Heating heater section 318 Heater cooling section 319 Resistance heating means 501 Photovoltaic layer 502 Fine metal wire 503 Metal electrode 504 Electrical junction 505 Conduction Conductive resin joint 511 Conductive resin coating 601 Solder 602 Conductive resin 702 Fine metal wire 703 Metal electrode 711 Conductive resin coating

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koichi Shimizu 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5F051 AA02 AA03 AA04 BA12 BA14 DA03 DA04 DA05 EA09 EA11 EA16 EA17 FA02 FA06 FA10 FA14 FA16 FA17 FA24 GA02 GA03 GA04

Claims (10)

[Claims] 1. A method of manufacturing a photovoltaic element comprising at least a photovoltaic layer, a thin metal wire covered with a conductive resin, and a metal electrode, wherein the conductive resin is removed from a surface of the thin metal wire. A second step of removing an oxide film and a conductive resin residue on the surface of the fine metal wire; and a second step of joining a conductive resin removed portion of the fine metal wire and the metal electrode with a brazing material. A method for manufacturing a photovoltaic element, comprising: 2. The photovoltaic device according to claim 1, wherein the first step is performed by irradiating the conductive resin with a rotating mirror or a rotating prism with a Q-switch modulated YAG laser beam. A method for manufacturing a power element. 3. The method according to claim 2, wherein the conductive resin contains a substance having a high energy absorption rate of laser light. 4. The method for manufacturing a photovoltaic device according to claim 3, wherein the substance having a high energy absorption rate of the laser beam is carbon black or graphite. 5. The method according to claim 1, wherein the second step uses ultraviolet light, microwave plasma treatment, ozone treatment, corona treatment, electron beam irradiation treatment or gamma ray treatment. A method for producing the photovoltaic element according to the above. 6. The method according to claim 1, wherein an aqueous solution of a peroxide or an acidic solution is used alone or in combination as the second step. 7. In the third step, a brazing material is formed on the surface of the metal electrode or the surface of the thin metal wire from which the conductive resin coating has been removed, and the metal electrode and the thin metal wire are formed by heating and pressing. The method for manufacturing a photovoltaic device according to claim 1, wherein the photovoltaic device is bonded to a metal. 8. The method according to claim 7, wherein a resistance heating means is used as the method of heating the brazing material. 9. The method for manufacturing a photovoltaic element according to claim 8, wherein said resistance heating means has a heater section and a heater cooling section. 10. A photovoltaic device manufactured by the method according to claim 1. Description: