JPH0982865A - Chip diode with lead terminal and solar cell module using this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the generation of heat from a chip diode with lead terminals and to make a stable solder bonding, which has not a squeeze-out of a solder and a bonding failure, of the chip device possible also from the viewpoint of manufacture by a method wherein conductive particles having a conductivity higher than that of the solder are mixed in the solder. SOLUTION: A chip diode 101, copper foils 102 and a solder paste 103 are respectively prepared. Here, the paste 103 is one made by a method wherein 10vol.% of copper particles are mixed in a creamy solder and after the particles are mixed with the solder in an earthenware mortar for 30 minutes, the mixure is passed through three rolling mills three times. When the amount of the copper particles to be mixed in the solder is too little, the effect of an increase in the conductivity of the particles and the effect of the inhibition of the fluidity of the particles can not be expected and when the amount of the particles is too much, a bonding force for bonding the coils 102 to the diode 101 is weakened. Then, the paste 103 is subjected to screen printing on the point parts of the foils 102 and the diode 102. Thereby, a chip diode with lead terminals of a stable solder bonding, which has not a squeeze-out of the solder and a bonding failure, from the viewpoint of manufacture can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip diode with a lead terminal and a solar cell module using the chip diode as a bypass diode.

[0002]

In recent years, is expected to global warming greenhouse of increased CO ₂ occurs, clean energy requirements that do not emit CO ₂ is increasingly. In addition, nuclear power generation that does not emit CO ₂ has not solved the problem of radioactive waste, and clean energy with higher safety is desired. Among such expected clean energy, solar cells are especially
It has received a great deal of attention because of its cleanliness, safety, and ease of handling.

Among various solar cells, the amorphous silicon solar cell has a conversion efficiency which is lower than that of a crystalline solar cell, but it is easy to increase the area, has a large light absorption coefficient, and operates in a thin film. It has one of the most promising future solar cells because it has excellent features not found in crystalline solar cells.

By the way, the output voltage of a solar cell corresponding to a battery is insufficient with only one solar cell. Therefore, usually, a plurality of solar cells are usually connected in series and used.

The biggest difficulty in operating a plurality of cells connected in series as described above is that when a part of the cells is blocked from sunlight due to the shadow of a building, snowfall, etc. That is, the total generated voltage from other elements that are normally generating power is directly applied in the form of a reverse voltage. When such a reverse voltage exceeds the breakdown voltage of the element, the element may be destroyed. Therefore, in order to avoid such destruction of the device,
For each element connected in series, it is necessary to connect a diode in parallel with the element in the opposite direction. Such a diode is generally called a bypass diode.

The bypass diode as described above is generally used as a general-purpose product, and a diode of a mold package in which a cover resin is provided around it is used. However, these diodes have a relatively large thickness. Therefore, for example, when the solar cell element is encapsulated with a filler such as EVA (ethylene vinyl acetate) in the subsequent step, only the portion of the bypass diode rises from the surface, which deteriorates the flatness of the solar cell module. Further, if it is attempted to completely fill such a bypass diode, it is necessary to increase the thickness of EVA,
This will lead to higher costs.

From such a background, for example, Japanese Patent Laid-Open No. 5-29
As described in Japanese Patent No. 1602, there is a case where a relatively thin chip diode is used without a mold package resin. FIG. 5 shows an example of such a diode. In this example, a copper foil 502 as a lead terminal is connected to the front surface and the back surface of the chip diode 501 by a lead-tin solder 503, respectively. The total thickness of the chip diode with lead terminals constructed in this way is 30 times that of the chip diode 501.
Assuming that the thickness of the copper foil 503 is 0 μm, the thickness of the copper foil 503 is 100 μm, and the thickness of the solder 503 is a little over 50 μm, it is about 600 to 700 μm.
Considering that it was 3 mm, it is quite thin.

The procedure for producing this chip diode with lead terminals is as follows. First, a solder pellet is placed on the chip diode, a copper foil is placed thereon, and a temperature at which the solder melts is applied while applying an appropriate pressure. As a result, the chip diode and the copper foil are solder-bonded, and a diode having a constant thickness can be created. In addition to solder pellets, screen printing may be used to supply solder.

[0009]

However, the above chip diode with lead terminals is installed as a bypass diode in a solar cell element and filled with a filling material such as EVA to prepare a solar cell module. When a suitable current is applied to the EVA, air bubbles are generated in the EVA due to the heat generated by the bypass diode, and a phenomenon occurs in which the white turbidity deteriorates the appearance. Further, when the heat generation is severe, there is a problem that the solar cell element near the bypass diode is destroyed by heat. This is a new phenomenon that occurs when a chip diode with lead terminals is used, which is not seen in a diode whose periphery is covered with mold package resin.

It has been found that this is due to the large heat generation in the solder portion of the chip diode with lead terminals. That is, normally the PN of the diode
The heat generated at the junction section passes through the solder section and is transferred to the copper foil with good conductivity to radiate heat. However, the solder section has a large resistance and is thicker than 50 μm, The heat accumulates and adversely affects EVA and the like.

Therefore, it is desirable to make the solder portion of the chip diode with lead terminals as thin as possible. This is also desirable in terms of reducing the thickness of EVA and reducing costs. As a method of reducing the thickness of the solder portion in this manner, it is conceivable to increase the pressure when the solder is melted to reduce the thickness of the solder portion, or to reduce the amount of solder.

However, when the pressure is increased to melt the solder, as shown in FIG.
The solder 503 overflows from the area 01. In particular, when the amount of protrusion is large, the two lead terminals are short-circuited and the manufacturing yield is deteriorated. And when connecting such a diode to the solar cell element,
The solar cell itself short-circuits and does not function.

Further, when the amount of solder is reduced, as shown in FIG.
As shown in, the solder 503 does not spread over the entire contact portion. For this reason, the adhesive area is reduced and the adhesive force is weakened, and conversely, the resistance is increased and the heat generation is increased, which causes the same problem as described above.

In view of the above-mentioned problems, the present invention provides a chip diode with a lead terminal capable of stable solder joining with less heat generation and no solder bleeding or joint failure in manufacturing, and a bypass diode for this chip diode. It is intended to provide a solar cell module used as the above.

[0015]

A chip diode with lead terminals according to the present invention has a structure in which a lead terminal is soldered to a chip diode, wherein conductive particles having a higher conductivity than solder are mixed in the solder. It is characterized by being

The volume percentage of the conductive particles with respect to the solder is preferably 5 to 50%. Further, the conductive particles are preferably made of at least one metal selected from Ag, Cu, Al, Zn and Sb.

Further, the solar cell module of the present invention is characterized in that, in a solar cell module in which a plurality of solar cell elements are connected in series, the above chip diodes with lead terminals are connected in parallel.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive particles described above may be in the form of spherical powder or flakes, and are not particularly limited, and may be a mixture thereof. Regarding the size, particles of a certain size may be mixed,
It may form a distribution.

When the amount of the conductive particles mixed in the solder is too small, the effect of increasing the conductivity and the effect of suppressing the fluidity cannot be expected so much, and when the amount is too large, the relative amount of the solder becomes small, so that the copper foil is reduced. The joining force for joining the chip diode and the chip diode will be weakened. From these tradeoffs, it is desirable to mix 5 to 50% by volume. More preferably, the effect is most remarkable when 10 to 30% by volume is mixed.

Here, as the kind of the conductive particles, specifically, Au, Ag, Cu, Ni, Al, which has good conductivity lower than the volume resistivity (1 × 10 ⁻⁵ Ωcm) of the solder, F
Various metal particles such as e, Zn and Sb can be used. Among these, Ag, Cu, Al, Zn, and Sb, which have a good compatibility with solder and a large effect of suppressing fluidity, are preferably used.

As the lead terminal, a material having a low volume resistivity and being supplied industrially stably is used, but a copper foil, which has good workability and is inexpensive, is preferably used.

When copper foil is used, corrosion prevention,
A thin metal layer may be provided on the surface for the purpose of preventing oxidation. As such a surface metal layer, silver, palladium,
Examples include alloys of palladium and silver, precious metals such as gold that are not easily corroded, and metals with good corrosion resistance such as nickel, tin, and solder.

As a method of forming the surface metal layer, a vapor deposition method, a plating method or a clad method, which are relatively easy to make, are preferably used.

The thickness of the lead terminal is preferably 70 μm or more and 150 μm or less. When the thickness is 70 μm or more, it is possible to secure a cross-sectional area that can sufficiently cope with the current density, it can be practically used as a mechanical coupling member, and it is possible to prevent adverse effects such as damage to the lead terminals caused by the connecting work. On the other hand, the thicker the lead terminal is, the smaller the resistance loss can be made. However, when the lead terminal is 150 μm or less, the surface coating material can be smoothly coated. If such a gentle coating is achieved, the step difference can be reduced. And, the smaller the step is, the thinner the surface coating material can be made, and the coating material can be saved.

An example of a solar cell element in which such a chip diode with lead terminals is connected as a bypass diode will be described with reference to FIG. Here, the solar cell element used in the present invention is applicable to a solar cell using a semiconductor other than silicon, a solar cell such as a Schottky junction type, in addition to being applicable to a single crystal, polycrystal or amorphous silicon solar cell. However, the case of an amorphous silicon solar cell will be described below as a representative.

The substrate 801 is a member that mechanically supports the semiconductor layer 803 in the case of a thin film solar cell such as amorphous silicon, and may also be used as an electrode. The substrate 801 is required to have heat resistance to withstand a heating temperature at the time of forming the semiconductor layer 803, but may be conductive or electrically insulating.

As the conductive material, specifically, N
i, Cr, Al, Mo, Au, Nb, Ta, V, Ti,
Examples thereof include metals such as Pt and Pb or alloys thereof, for example, thin plates such as brass and stainless steel and their composites, carbon sheets, and galvanized steel plates. Further, as the electrically insulating material, a film or sheet of heat-resistant synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide and epoxy, or these and glass fiber , A composite of carbon fiber, boron fiber, metal fiber, etc., and a metal thin film and / or S of a different material on the surface of a thin plate or a resin sheet of these metals.
Examples thereof include those obtained by subjecting an insulating thin film such as iO ₂ , Si ₃ N ₄ , Al ₂ O ₃ and ITN to a surface coating treatment by a sputtering method, a vapor deposition method, a plating method, glass, ceramics and the like.

The lower electrode 802 is one electrode for taking out electric power generated in the semiconductor layer 803, and is required to have a work function that makes an ohmic contact with the semiconductor layer 803. The material of the lower electrode 802 is Al, Ag, Pt, Au, Ni, Ti, M.
o, Fe, V, Cr, Cu, stainless steel, brass, nichrome, SnO ₂ , In ₂ O ₃ , ZnO, so-called metal simple substance or alloy such as ITO, and transparent conductive oxide (T
CO) or the like is used.

Although the surface of the lower electrode 802 is preferably smooth, it may be textured if it causes irregular reflection of light. Further, when the substrate 801 is conductive, the lower electrode 802 need not be provided. As a method of forming the lower electrode 802, a method such as plating, vapor deposition, sputtering or the like is used.

The semiconductor layer 8 of the solar cell used in the present invention
As 03, a known semiconductor material generally used as a thin film solar cell can be used. In particular,
Examples thereof include a pin-junction amorphous silicon layer, a pn-junction polycrystalline silicon layer, and a compound semiconductor layer such as CuInSe ₂ / CdS. As a method for forming the semiconductor layer 803, in the case of an amorphous silicon layer, it can be formed by plasma CVD or the like in which plasma discharge is generated in a raw material gas such as a silane gas which forms a film. Here, the pn junction polycrystalline silicon layer is formed by, for example, a film forming method of forming a film from molten silicon. Further, the above CuInSe ₂ / CdS is formed by a method such as an electron beam vapor deposition method, a sputtering method and an electrodeposition method.

The upper electrode 804 is an electrode for taking out the electromotive force generated in the semiconductor layer 803, and the lower electrode 80
It forms a pair with 2. The upper electrode 804 is necessary in the case of a semiconductor having a high sheet resistance such as amorphous silicon, and is not particularly necessary in a crystalline solar cell because it has a low sheet resistance.

Since the upper electrode 804 is located on the light incident side, it needs to be transparent and is also called a transparent electrode. The upper electrode 804 preferably has a light transmittance of 85% or more in order to efficiently absorb light from the sun, a white fluorescent lamp, or the like in the semiconductor layer. Further, electrically, a current generated by light is used. It is desirable that the sheet resistance value is 100 Ω / □ or less in order to allow the liquid crystal to flow laterally with respect to the semiconductor layer. Materials having such characteristics include SnO ₂ , In ₂ O ₃ , ZnO, CdO, and CdSn.
Examples thereof include metal oxides such as O ₄ and ITO (In ₂ O ₃ + SnO ₂ ).

The collector electrode 805 used in the present invention is generally formed in a comb shape, and has a semiconductor layer 803 and an upper electrode 804.
The suitable width and pitch are determined from the sheet resistance value of.
The collector electrode 805 is required to have a low specific resistance so as not to be a series resistance of the solar cell, and a preferable specific resistance is 10 ^-2.
Ωcm to 10 ⁻⁶ Ωcm. The material of the collecting electrode 805 is Ti, Cr, Mo, W, Al, Ag, Ni, C.
A metal such as u, Sn, or Pt, an alloy thereof, or solder is used. Generally, a metal paste in which a metal powder and a polymer resin binder are in a paste form is used, but the present invention is not limited to this. For example, one using a metal wire or the like may be used.

Busbar electrode 806 used in the present invention
Is an electrode for further collecting the current flowing through the collector electrode 805 at one end. As the electrode material, Ag, Pt,
A metal such as Cu or an alloy thereof can be used, and a wire-shaped or foil-shaped one is attached as a form. Examples of foil-shaped products include copper foil,
Alternatively, a copper foil tin-plated with an adhesive is used in some cases. Also, the place where it is provided does not have to be in the center of the solar cell element, and may be in the vicinity of the solar cell element.

In FIG. 8, reference numeral 807 denotes a conductive adhesive material for ensuring the connection between the collector electrode 805 and the bus bar electrode 806.

Next, the packaging material that covers the entire solar cell element will be described. The basic structure of this packaging material is as shown in FIG.
The surface sealing material 902 and the back surface sealing material 903 are classified.

The surface sealing material 902 covers the irregularities of the photovoltaic element with a resin, protects the element from a harsh external environment such as temperature change, humidity, and shock, and secures the adhesion between the outermost surface material and the element. Is necessary for. Therefore, weather resistance, adhesion, filling properties, heat resistance, cold resistance, and impact resistance are required.

Resins satisfying these requirements include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), polyvinyl butyral resin. Examples include polyolefin resins, urethane resins, silicone resins, fluororesins, and the like. Among them, EV
A has well-balanced physical properties for use in solar cells and is preferably used. However, since the heat deformation temperature is low as it is, it easily deforms and creeps under high temperature use. Therefore, it is desirable to increase the heat resistance by crosslinking.

Since the outermost surface material 901 is located on the outermost surface layer of the solar cell module, it has weather resistance, stain resistance, mechanical strength, and other properties for ensuring long-term reliability in outdoor exposure of the solar cell module. is necessary. Materials that are preferably used include fluororesin and acrylic resin. Among them, fluororesins are preferably used because of their excellent weather resistance and stain resistance.

Specifically, polyvinylidene fluoride resin,
Examples include polyvinyl fluoride resin and tetrafluoroethylene-ethylene copolymer. From the viewpoint of weather resistance, the polyvinylidene fluoride resin is excellent, but the tetrafluoroethylene-ethylene copolymer is excellent in terms of both weather resistance and mechanical strength and transparency. Further, the outermost surface material 901 is not limited to resin, and even if glass is used, there is no problem.

Next, as the back surface sealing material 903, it is preferable to use a material capable of ensuring sufficient adhesiveness to the substrate and excellent in long-term durability. As a material preferably used, EV
A, a hot melt material such as polyvinyl butyral, a double-sided tape, and an epoxy adhesive having flexibility.
In addition, a reinforcing plate may be attached to the outside of the back surface sealing material 903 in order to increase the mechanical strength of the solar cell module or prevent distortion and warpage due to temperature change. For example, a steel plate, a plastic plate, or an FRP (glass fiber reinforced plastic) plate is preferable. Various known methods such as vacuum lamination and roll lamination can be used as the thermocompression bonding method.

In the chip diode with lead terminals, the volume resistivity of the solder itself can be lowered by mixing the conductive particles having good conductivity into the solder, whereby heat generation in the solder portion can be suppressed as compared with the conventional case. It is possible to prevent bubbles from being generated in the resin such as EVA. Further, mixing the conductive particles can also suppress the fluidity of the solder. Therefore, when the solder is melted while applying pressure, the solder does not flow and can be solidified at the position as it is, so that there is no solder squeeze-out or joint failure,
Stable manufacturing becomes possible.

When this chip diode with lead terminals is connected in parallel to each solar cell element of the solar cell module, a solar cell module which does not cloud the filling material or destroy the element due to heat generation of the diode is supplied. can do.

[0044]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below. First, as shown in FIG. 1A, a chip diode 101 (4.5 mm square, 280 μm thick silicon PN diode), a copper foil 102 (soft copper 100 μm thick), and a solder paste 103 were prepared. Here, the solder paste 103 was prepared by mixing 10% by volume of copper particles (spherical powder, diameter of about 1 μm) into cream solder (RX363: manufactured by Nippon Solder Co., Ltd.) and mixing in a mortar for 30 minutes.
It was passed three times with a three-roll mill. Next, copper foil 1
The solder paste 103 was screen-printed on the tip portion of No. 02 and the chip diode 101 by a screen printing machine and placed in the order shown in FIG.

These were placed on a heater at 200 ° C., the solder was melted while applying a constant pressure with a weight in the direction of the arrow in the figure, and the members 101 and 102 were solder-bonded. At this point, the total thickness was about 580 μm, and no solder squeeze-out or defective joining was visually observed.

Ten samples of the chip diode with lead terminals as described above were prepared, and the CA thermocouple 104 was placed directly on the copper foil 102 as shown in FIG.
Lamination was performed with A105. Furthermore, FIG.
A circuit as shown in (d) is formed, and a constant current of 3.8 A that may flow in an actual solar cell element is passed in the forward direction of the chip diode for 30 minutes to keep the temperature stable at 30 ° C.
The temperature was read by a digital voltmeter after a minute. The data of film thickness and temperature of 10 samples are shown below.

[0047]

[Table 1]

That is, the average film thickness of 10 samples is 57
The average temperature was 105.7 ° C. Also,
No solder protrusion or the like was observed in any of the 10 samples. Therefore, by mixing fine metal particles such as copper particles into the solder, it is possible to fabricate a stable assembly diode without the solder protruding.

Comparative Example 1 For comparison, 10 samples were prepared in exactly the same manner as in Example 1 except that copper particles were not added to the solder paste. One of the 10 samples caused a short circuit between the copper foils due to the solder squeeze out. Below, the data of the film thickness and temperature of the remaining 9 samples are shown.

[0050]

[Table 2]

That is, the average film thickness of the 9 samples is 579.
It was 7 μm and the average temperature was 121.1 ° C. When these were compared with Example 1, the film thickness was almost unchanged, but the temperature increased by about 15 ° C. From this, it is considered that by mixing the copper particles in the solder, the conductivity was improved and the heat generation was suppressed.

(Second Embodiment) A second embodiment of the present invention will be described below. By the same dispersion method as in Example 1, 2% by volume of Al particles (spherical powder, average diameter of about 5 μm) in cream solder (RX363: manufactured by Nippon Solder Co., Ltd.) were used.
%, 10%, 20%, 30%, 50%, 80% mixed solder pastes A, B, C, D, E, F, C were prepared.

When the volume resistivities of these solder pastes when melted were measured, the results shown in FIG. 2 were obtained. Further, FIG. 3 shows the result of the 180 ° peel test of the lead copper foil and the chip diode after melting the solder.

The volume resistivity tends to decrease as the Al particles are mixed, and it is almost saturated when the Al particles are mixed in an amount of 10% or more. With respect to the peeling force, up to 30%, there is no change in the peeling force as compared with the case of 0% in which nothing is mixed, but the peeling force starts to gradually decrease from about 50% mixing, and becomes considerably weak up to 80%.
It is considered that this is because the joining force of the solder hardly works when the Al particles are large.

Further, using these seven kinds of solder pastes, a sample similar to that of Example 1 was prepared and the temperature was measured. The following results were obtained. Each result is an average of 3 samples. Further, with respect to Sample A, no short circuit was found, but solder protrusion was visually confirmed.

[0056]

[Table 3] The result of the above temperature measurement was almost in agreement with the result of the volume resistivity of the solder, and the tendency was lowered as the metal particles were mixed.

As described above, considering the result of 180 degree peeling and the result of visual inspection, there is no solder protrusion,
In order to provide an assembly diode that is also strong in terms of strength, the amount of the metal fine particles mixed is optimally 5 to 50% by volume. Furthermore, under these conditions, a sufficient effect of suppressing heat generation of the solder part was obtained.

(Embodiment 3) Next, a third embodiment of the present invention will be described. In this embodiment, the above-mentioned chip diode with lead terminals is connected to an amorphous silicon solar cell using a stainless steel substrate as a substrate. This will be specifically described with reference to FIG. Here, FIG.
4A is a schematic view of the solar cell element as seen from the light incident surface side, FIG. 4B is a schematic view of a bypass diode composed of the chip diode with a lead terminal produced, and FIG. 4C is the sun of FIG. 4A. It is the figure which showed the outline which connected this bypass diode to the battery element.

First, as a substrate for a solar cell element, a roll-shaped stainless substrate made of a stainless steel foil having a thickness of 0.1 mm and having a cleaned surface was prepared. Next, a plurality of solar cell elements 400 were simultaneously formed on the surface of this stainless steel substrate. This solar cell element 400 is a structure having a multilayer film shown in the table below.

[0060]

[Table 4]

The roll-shaped stainless steel substrate on which the multilayer film was formed by the above process was divided into solar cell elements by cutting. In this way, 10 solar cell elements 400 shown in FIG. 4A were manufactured (only 3 are shown in the figure).

The following processes (1) to (9) are sequentially performed on the solar cell element 400 to obtain the solar cell element group A.
Was produced.

(1) ITO on the solar cell element 400
After the etching material (FeCl ₃ ) containing paste of ( ₁ ) was screen-printed on the pattern of 401, it was washed with pure water to remove a part of the ITO layer and ensure the electrical separation between the upper electrode and the lower electrode.

(2) Part of the ITO layer, a-Si layer and lower electrode layer in the non-effective power generation region of each solar cell element is removed by a grinder to expose the stainless substrate surface 402 and take it out from the lower electrode. Part and

(3) A 0.3 mm wide collector electrode 403 was formed on ITO by screen-printing a silver paste and firing it open.

(4) In order to ensure the insulation between the pass bar electrode 405 and the lower electrode, which will be described later, a polyimide insulating tape (thickness 100 μm) 408 was attached adjacent to the exposed surface of the substrate.

(5) After attaching the insulating tape 404, the bus bar electrode 405 is placed as shown in the figure, the silver paste 406 is put on the bus bar electrode 405 and baked in the oven to collect the current. And bus bar electrode 4
05 connections were made. Thereby, the bus bar electrode 405
Serves as one of the extraction electrodes of the solar cell element.

(6) Next, using the solder paste E described in Example 2, an assembly diode 409 having a shape as shown in FIG. 4B was produced. Here, the chip diode 408 is a silicon PN diode having a size of 4.5 mm square and a thickness of 280 μm, and the copper foil 407 is 1
Soft copper with a thickness of 00 μm was used.

(7) A copper foil 410 having a thickness of 100 μm is shown in FIG.
It was placed at the position shown in (c), and the intersecting portion with the bus bar electrode 405 and the contacting portion with the substrate exposed surface 404 were electrically connected by soldering. In this way, 10 series solar cell elements were connected.

(8) Further, the diode shown in FIG. 4 (b) was placed at the position shown in FIG. 4 (c), and the contact portion with the copper foil 410 was electrically connected by soldering. In this way, the diode connection was completed in parallel with each element.

(9) A solar cell element group B was manufactured in the same manner as in steps (1) to (8) except that a solder paste (RX363) containing no fine metal particles was used.

The solar cell element group A manufactured as described above,
The following processing was performed on B. EVA sheet (made by Springborn Laboratories, product name Photocap, thickness 460μ on the light receiving surface side of the solar cell element group)
m) and a uniaxially stretched ETFE film (manufactured by DuPont, trade name Tefzel T2 film, thickness: 38 μm) whose one side is subjected to corona discharge treatment, and an EVA sheet (manufactured by Springborn Laboratories, trade name Photo Cap) on the back side.
Thickness 460 μm) and nylon film (Dupont,
Product name: DATEC, thickness 63.5μm) and black painted galvalume steel plate (galvanized steel plate, thickness 0.27)
mm) to ETFE / EVA / Solar cell element group / EVA /
Nylon / EVA / steel sheets were layered in this order, and solar cell modules A and B were obtained by heating at 150 ° C. for 30 minutes while depressurizing and using a vacuum laminating apparatus.

The EVA sheet used here is widely used as a sealing material for solar cells.
1.5 parts by weight of cross-linking agent, 0.3 part by weight of ultraviolet absorber, 0.1 part by weight of light stabilizer, 0.2 part by weight of antioxidant per 100 parts by weight of resin A (vinyl acetate content 33%). Parts, and 0.25 parts by weight of a silane coupling agent. The output terminal was previously turned on the back surface of the photovoltaic element, and after lamination, the output could be taken out from the terminal take-out opening previously opened in the galvalume steel plate.

The solar cell modules A and B produced as described above are placed in a room having a room temperature of 85 ° C. and a humidity of 85%, and 3.8 A which may flow in the forward direction of the diode with an actual solar cell element. The constant current was applied for 1000 hours to perform an acceleration test.

When the appearance of the solar cell module was observed after 1000 hours, no change was observed in the appearance of the solar cell module A except that it slightly yellowed. In contrast,
In the solar cell module B, bubbles were generated from EVA near the diode, and cloudiness was generated to the extent that the diode could not be seen. Furthermore, yellowing, which is considered to be due to heat deterioration of the resin, was observed.

From the above results, the diode manufactured by using the solder paste mixed with the metal fine particles does not spoil the appearance of the solar cell due to the effect of reducing heat generation in the solder portion.

[0077]

As described above, according to the present invention, by mixing the highly conductive metal fine particles in the solder, a diode with a lead terminal can be obtained which is stable and does not squeeze out of the solder or is defective in manufacturing. be able to. Then, by using the diode with the lead terminal as a bypass diode of the solar cell module, it is possible to provide a diode that does not impair the appearance.

[Brief description of drawings]

1A to 1D are explanatory views of a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the amount of one particle in solder and the volume resistivity in Example 2 of the present invention.

FIG. 3 is a graph showing the relationship between the amount of Al particles in solder and the peeling force in Example 2 of the present invention.

4A to 4C are explanatory views of a third embodiment of the present invention.

FIG. 5 is a schematic view of a conventional chip diode.

FIG. 6 is an explanatory diagram of a problem of the present invention.

FIG. 7 is an explanatory diagram of a problem of the present invention.

FIG. 8 is an explanatory diagram of a solar cell element used in the present invention.

FIG. 9 is an explanatory diagram of a packaging material used in the present invention.

[Explanation of symbols]

 101, 108, 501 chip diode, 102, 407, 502 lead terminal, 103, 503 solder, 104 thermocouple, 105 EVA, 400 solar cell element, 401 etching line, 402 substrate exposed portion, 403, 805 current collecting electrode, 404 Insulating tape, 405, 806 bus bar electrode, 406, 807 conductive adhesive, 409 assembly diode, 410 copper foil, 801 substrate, 802 lower electrode layer, 803 semiconductor layer, 804 upper electrode layer, 901 outermost surface material, 902 surface sealing Stopping material, 903 Backside sealing material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 31/042 H01L 31/10 A 31/10

Claims (4)

[Claims] 1. A chip diode with a lead terminal, in which a lead terminal is solder-bonded to a chip diode, wherein conductive particles having a higher conductivity than solder are mixed in the solder. diode. 2. The chip diode with lead terminal according to claim 1, wherein the volume percentage of the conductive particles with respect to the solder is 5 to 50%. 3. The conductive particles are Ag, Cu, Al, Z.
3. The chip diode with lead terminal according to claim 1, wherein the chip diode with lead terminal is made of at least one metal selected from n and Sb. 4. In a solar cell module in which a plurality of solar cell elements are connected in series, the chip diode with a lead terminal according to claim 1 is connected in parallel to each of the solar cell elements. The solar cell module is characterized by