JP4427843B2 - Electronic component and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic component such as a solar cell and a manufacturing method thereof.
[0002]
[Prior art]
Solar cells are used in various electronic devices as a power source that replaces dry cells and the like. In particular, low power consumption electronic devices such as electronic desk calculators, watches, portable electronic devices (cameras, mobile phones, consumer radar detectors), remote controls, etc., can be driven sufficiently by the electromotive force of solar cells. It is attracting attention because it can be operated semi-permanently and is environmentally clean. In general, a Si layer such as an amorphous silicon (a-Si) layer or a microcrystalline Si (μc-Si) layer is used for a photoelectric conversion layer of a solar cell.
[0003]
A solar cell is configured by laminating a lower electrode, a photoelectric conversion layer, and a transparent electrode on the surface of a rigid or flexible substrate. As the substrate, an organic flexible substrate that is flexible and can be wound and unfolded from the viewpoint of workability, workability, and the like is often used. As the photoelectric conversion layer, an Si layer formed by plasma CVD is usually used.
[0004]
In a solar cell, it is necessary to provide a plus-side extraction electrode and a minus-side extraction electrode in order to extract generated power. In a small or portable electric / electronic device such as a remote controller, a calculator, a telephone, a watch, etc., it is necessary to take out electric power from the back side of the substrate for the convenience of mounting solar cells.
[0005]
When both of the pair of extraction electrodes are provided on the back side of the substrate, it is necessary to draw a conductive path from the transparent electrode and the lower electrode existing on the front side of the substrate through the substrate to the back side and connect them to the extraction electrode. When forming one extraction electrode that is electrically connected to the transparent electrode, for example, a through hole that penetrates the transparent electrode, the photoelectric conversion layer, the lower electrode, and the insulating substrate is provided by laser processing, and in the vicinity of the through hole, Electrodes are formed by applying a conductive paste to the front side and the back side of the substrate, respectively. The electrode on the front surface side and the electrode on the back surface side are connected in the through hole, and the electrode on the back surface side becomes the take-out electrode. In this case, the lower electrode in the through hole forming region is electrically insulated from the lower electrode in the power generation region. Similarly, for the other extraction electrode that is electrically connected to the lower electrode, a conductive path can be formed by providing a through hole in the insulating substrate.
[0006]
[Problems to be solved by the invention]
The present invention provides an electronic component having an internal electrode constituting at least part of an internal circuit on one surface side of an insulating substrate and an external electrode for electrically connecting to the outside on the other surface side. For example, an object of the present invention is to improve component characteristics and reliability in a solar cell having a structure in which generated electric power is extracted from the back side of an insulating substrate.
[0007]
[Means for Solving the Problems]
Such an object is achieved by the present inventions (1) to (6) below.
(1) An internal substrate has an internal electrode on one surface side and an external electrode on the other surface side, and the internal electrode and the external electrode are in contact with each other in a through-hole provided in the insulating substrate. Electronic components,
An electronic component in which the internal electrode contains conductive particles having a relatively small diameter and the external electrode contains conductive particles having a relatively large diameter.
(2) The electronic component according to (1), wherein a region in which the large-diameter conductive particles and the small-diameter conductive particles are mixed exists in the through hole.
(3) The above-mentioned large-diameter conductive particles mainly exist near the inner wall surface of the through-hole, and the small-diameter conductive particles exist near the central axis of the through-hole and between the large-diameter conductive particles. Electronic component of (1).
(4) A solar cell having a lower electrode, a photoelectric conversion layer, and a transparent electrode in this order on the surface of the insulating substrate,
The electronic component according to any one of (1) to (3), wherein the internal electrode is electrically connected to the lower electrode or the transparent electrode, and the external electrode functions as an extraction electrode.
(5) A method for manufacturing the electronic component according to any one of (1) to (4) above,
After printing the conductive paste containing the small-sized conductive particles, the internal electrode forming step for drying and curing, and after forming the conductive paste containing the large-sized conductive particles, the external electrode forming step for drying and curing. Manufacturing method of electronic components.
(6) The method for manufacturing an electronic component according to (5), wherein the internal electrode forming step is provided after the external electrode forming step.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Solar cell
A configuration example of a solar cell, which is an example of the electronic component of the present invention, is shown in FIG.
[0009]
The solar cell shown in FIG. 3 has a laminated body in which the lower electrode 4, the photoelectric conversion layer 5, and the transparent electrode 6 are laminated in this order on the surface side of the insulating substrate 2 (upper side in the drawing). The insulating substrate 2 is made of an insulating material such as resin. On one end side (left side in the figure) of the laminate, an interlayer insulating layer 9A exists between the photoelectric conversion layer 5 and the transparent electrode 6, and a separator insulating layer 10A exists on the transparent electrode 6. The one-side separator insulating layer 10 </ b> A has a separator portion 101 </ b> A that penetrates the transparent electrode 6, the interlayer insulating layer 9 </ b> A, the photoelectric conversion layer 5, and the lower electrode 4. One end of the laminate is insulated from the power generation region by the separator portion 101A.
[0010]
On the one end side of the insulating substrate 2, a through hole 40 </ b> A is provided in a region where the laminated body composed of the lower electrode 4, the photoelectric conversion layer 5, and the transparent electrode 6 does not exist. An internal electrode 51A is provided on the front side of the substrate 2, and an external electrode 52A is provided on the back side (lower side in the figure). In the through hole 40A, the internal electrode 51A and the external electrode 52A are in contact with each other. The internal electrode 51A is connected to the transparent electrode 6 at the end of the power generation region. In this configuration, the external electrode 52A functions as a positive extraction electrode.
[0011]
On the other hand, on the other end side of the solar cell, an interlayer insulating layer 9B exists between the photoelectric conversion layer 5 and the transparent electrode 6, and a separator insulating layer 10B exists on the transparent electrode 6. The other end-side separator insulating layer 10 </ b> B has a separator portion 101 </ b> B that penetrates the transparent electrode 6, the interlayer insulating layer 9 </ b> B, and the photoelectric conversion layer 5. The other end of the laminate is insulated from the power generation region by the separator portion 101B except for the lower electrode 4. The internal electrode 51B is present on the transparent electrode 6 on the end side of the separator portion 101B. The internal electrode 51B and the lower electrode 4 are electrically connected by a connection conductor 12B that penetrates the photoelectric conversion layer 5 and the transparent electrode 6.
[0012]
Then, on the other end side of the insulating substrate 2, a second through hole (hereinafter simply referred to as a through hole) 40 </ b> B is provided in a region where the laminated body including the lower electrode 4, the photoelectric conversion layer 5, and the transparent electrode 6 does not exist. Is provided. The internal electrode 51B is provided on the front surface side of the insulating substrate 2 and the external electrode 52B is provided on the back surface side of the through hole 40B. In the through hole 40B, the internal electrode 51A and the external electrode 51B are in contact with each other. In this configuration, the external electrode 52B functions as a negative extraction electrode.
[0013]
In the illustrated configuration, the external electrode 52A connected to the internal electrode 51A functions as one extraction electrode, and the external electrode 52B connected to the internal electrode 51B functions as the other extraction electrode. Therefore, in this configuration, electric power can be taken out from the back side of the insulating substrate 2.
[0014]
In the illustrated solar cell, light enters from the surface of the insulating substrate. The photoelectric conversion layer 5 is preferably a pin junction in which a p-type semiconductor layer, a photovoltaic layer (i layer), and an n-type semiconductor layer are arranged in this order from the light incident side in terms of power generation efficiency. The electrode 52A is indicated as a positive extraction electrode, and the external electrode 52B is indicated as a negative extraction electrode. However, in the present invention, the stacking order in the photoelectric conversion layer is not limited.
[0015]
Further, the structure in the vicinity of the extraction electrode is not limited to the illustrated example as long as it can extract electric power from the back surface side of the insulating substrate 2, and may be another structure. For example, by patterning when forming the photoelectric conversion layer 5 and the transparent electrode 6, the lower electrode 4 is exposed from the laminate on the right end side in the figure, and the exposed lower electrode 4 is directly connected to the internal electrode 51B. Or it is good also as a structure connected indirectly through a conductive pad etc. In addition, a laminated body composed of the lower electrode 4, the photoelectric conversion layer 5, and the transparent electrode 6 is formed up to both ends of the insulating substrate 2, and a through hole is provided through the laminated body and the insulating substrate 2. Also good.
[0016]
Next, the configuration related to the extraction electrode will be described in detail. In the following, only the through hole 40A side in FIG. 3 will be described, but the same applies to the through hole 40B side.
[0017]
The through hole 40A can be formed, for example, by mechanical processing of an insulating substrate. The diameter of the through hole may be appropriately determined as necessary, but is usually about 30 to 100 μm.
[0018]
The internal electrode 51A and the external electrode 52A are formed by using a conductive paste containing conductive particles, forming a coating film by a coating method such as a screen printing method, and drying and curing the coating film.
[0019]
FIG. 1B and FIG. 2B are enlarged cross-sectional views in the vicinity of the through hole 40A after the internal electrode and the external electrode are formed. The internal electrode contains conductive particles 51a having a relatively small diameter as compared with the conductive particles 52a contained in the external electrode. Therefore, when both electrodes are formed by coating, both small-diameter conductive particles 51a and large-diameter conductive particles 52a exist in the through hole 40A.
[0020]
The reason why the conductive particles having a small diameter are used for forming the internal electrode 51A is to reduce the sheet resistance of the internal electrode 51A, and the reason why the conductive particles having a large diameter are used for forming the external electrode 52A is that of the sheet resistance of the external electrode 52A. This is to increase the height. Since the internal electrode 51A constitutes a part of the internal circuit of the solar cell, the electric resistance is lowered in order to increase the efficiency of the entire solar cell. On the other hand, since the external electrode 52A is electrically connected to the outside of the solar cell, the electric resistance is increased in order to prevent external static electricity from entering the inside of the circuit of the solar cell, that is, the surface side of the insulating substrate 2. To do. By setting the particle diameters of the conductive particles contained in the internal electrode and the external electrode in such a relationship, a solar cell with good characteristics and high reliability is realized.
[0021]
When manufacturing the conventional solar cell, the present inventors first form each layer such as the lower electrode 4, the photoelectric conversion layer 5, and the transparent electrode 6 on the surface side of the insulating substrate 2, and then the internal electrode. 51A was formed, and then the external electrode 52A was formed. That is, the external electrode 52A is applied after the internal electrode 51A is dried and cured. However, when this manufacturing procedure is applied to the case where conductive particles having different particle diameters are used for the internal electrode 51A and the external electrode 52A, there may be a problem that the through-hole portion has a high resistance or poor conduction. all right.
[0022]
As a result of analyzing the solar cell in which such high resistance and poor conduction have occurred, the present inventors have established the internal electrode forming step before the external electrode forming step as described below. I found out that it was due to that. A cross-sectional view of the vicinity of the through-hole 40A after the internal electrode is dried and cured is schematically shown in FIG. In FIG. 2A, the small-diameter conductive particles 51a contained in the internal electrode penetrate into the through hole 40A and mainly exist in the vicinity of the inner wall surface. After this state is reached, when a conductive paste containing large-diameter conductive particles 52a is printed from the lower side in the drawing to form external electrodes, the state shown in FIG. 2B is obtained. That is, since the small-diameter conductive particles 51a are dried and hardened near the inner wall surface of the through-hole 40A, the large-diameter conductive particles 52a entering from the lower side mainly exist near the central axis of the through-hole 40A. Become. As a result, it is difficult to ensure surface contact between the large-diameter conductive particles 52a and the small-diameter conductive particles 51a, so that a point contact state is likely to occur, and high resistance and poor conduction are likely to occur.
[0023]
Based on such considerations, in a preferred embodiment of the present invention, the external electrode is first formed and then the internal electrode is formed. A cross-sectional view of the vicinity of the through-hole 40A after the external electrode is dried and cured is schematically shown in FIG. In FIG. 1A, the large-diameter conductive particles 52a contained in the external electrode enter the through hole 40A and mainly exist near the inner wall surface. After this state is reached, when a conductive paste containing small-diameter conductive particles 51a is printed from the upper side in the drawing to form internal electrodes, the state shown in FIG. 1B is obtained. That is, the small-diameter conductive particles 51a that have entered from the upper side are filled in the vicinity of the central axis of the through-hole 40A and are also filled in the gaps that exist between the large-diameter conductive particles 52a. As a result, sufficient surface contact can be ensured between the large-diameter conductive particles 52a and the small-diameter conductive particles 51a, so that the occurrence of high resistance and poor conduction can be suppressed. Note that the large diameter conductive particles and the small diameter conductive particles may not be in the distribution state shown in FIG. However, if the internal electrode is applied and dried and cured after the external electrode is dried and cured, a region where both conductive particles are mixed in the through hole, that is, small conductive particles exist between the large conductive particles. Since the region can be formed, the effect of suppressing the increase in resistance and conduction failure is similarly realized.
[0024]
The conductive paste for forming each of the internal electrode and the external electrode contains conductive particles, a binder, a solvent, various additives, etc., and is selected from commercially available conductive pastes according to required characteristics such as sheet resistance. Can do. The constituent material of the conductive particles is not particularly limited. For example, a metal material such as Ag or Cu or carbon may be used. In particular, it is preferable to use a high-resistance material such as carbon for the external electrode that is required to have a relatively high resistance.
[0025]
The effect of the method of forming the external electrode before the internal electrode is realized if the particle diameter of the small-diameter conductive particles 51a is relatively smaller than the particle diameter of the large-diameter conductive particles 52a. However, in the above method, the small conductive particles 51a contain 75% by volume or more of particles having a particle size in the range of 0.1 to 4 μm, and the large conductive particles 52a have a particle size of 5 to 15 μm. This is particularly effective when the particles are contained in 80% by volume or more. The shape of the conductive particles is not particularly limited, and may be any shape such as a spherical shape or an indefinite shape. In addition, the said particle size is a long diameter of what can be confirmed as individual particle | grains when it observes with a scanning electron microscope, and when it is secondary particle | grains, it is a long diameter of a secondary particle. These particle sizes are values measured after drying and curing.
[0026]
Next, a preferable configuration of each part other than the extraction electrode will be described with reference to FIG. FIG. 4 is a cross-sectional view mainly showing the central part of the solar cell configuration example.
[0027]
The solar cell shown in the figure has a lower electrode 4, a photoelectric conversion layer 5, and a transparent electrode 6 in this order on the surface side of the insulating substrate 2 as in FIG.
[0028]
The illustrated solar cell has a configuration in which a plurality of solar cells each having a light receiving surface are connected in series. A collecting / wiring electrode 11 is provided on the transparent electrode 6 of each cell. The collecting / wiring electrode 11 shown in the figure is a connecting portion between the collecting electrode and the wiring electrode. The collecting electrode is an electrode for collecting the electric power generated in each cell from the surface of the transparent electrode 6 having a relatively high specific resistance. The wiring electrode is an electrode for connecting the collection electrode of each cell and the lower electrode of the adjacent cell. In the illustrated example, the connection conductor 12 extends from the collection / wiring electrode 11 through the transparent electrode 6 and the photoelectric conversion layer 5 and is connected to the lower electrode 4 of the adjacent cell, whereby the adjacent cells are connected in series. It is connected. An interlayer insulating layer 9 exists in a part between the transparent electrode 6 and the photoelectric conversion layer 5, and a separator insulating layer 10 exists on the interlayer insulating layer 9 with the transparent electrode 6 interposed therebetween. In the illustrated example, the separator portion 101 of the separator insulating layer 10 extends through the transparent electrode 6, the photoelectric conversion layer 5, and the lower electrode 4 and insulates the lower electrodes of adjacent cells. Separator portion 101 is a wall-like body that also extends in the depth direction in the figure.
[0029]
Note that, as shown in FIG. 3, positive and negative extraction electrodes are provided at both ends of the series connection, respectively.
[0030]
Although not shown, it is preferable to provide a sealing member on at least the transparent electrode 6 formation side surface of the illustrated solar cell in order to suppress mechanical damage, oxidation, corrosion, and the like of the solar cell. Such a sealing member is also preferably provided on the back side of the insulating substrate 2.
[0031]
Hereinafter, the configuration of each unit will be described in detail.
[0032]
Insulating substrate
Although the insulating material which comprises the insulating substrate 2 is not specifically limited, Usually, it is preferable to use an organic material or glass. Examples of the organic material include polyethylene naphthalate (PEN), polyethersulfone (PES), polyimide, polyamide, polyimide amide, and polyarylate.
[0033]
The thickness of the insulating substrate may be appropriately determined according to the required strength, bending rigidity, constituent material, etc., but is usually preferably 25 to 100 μm.
[0034]
Bottom electrode
The lower electrode 4 is preferably made of metal. The lower electrode constituent material is not particularly limited. For example, Al or stainless steel may be used, but Al is preferably used. Since Al has a low specific resistance, deterioration due to energy loss and heat generation is small. By the way, in the solar cell, the light reflected by the lower electrode through the photoelectric conversion layer again enters the photoelectric conversion layer, and this reflected light is also converted into electric energy. Therefore, it is preferable that the lower electrode has a high reflectance, but Al having a high light reflectance is also excellent in this respect. Furthermore, Al has high thermal conductivity, good corrosion resistance, and is inexpensive.
[0035]
Although the thickness of a lower electrode is not specifically limited, Preferably it is 0.01-10 micrometers. The lower electrode is preferably formed by a vapor phase growth method such as a sputtering method.
[0036]
Diffusion prevention layer
Between the lower electrode 4 and the photoelectric conversion layer 5, a metal such as stainless steel, Ti, or Cr is used to prevent the lower electrode components from diffusing into the photoelectric conversion layer and to reduce the interface between the two. It is preferable to provide a diffusion prevention layer comprising The thickness of the diffusion preventing layer is preferably 3 to 5 nm. The diffusion preventing layer may be usually formed by a vapor phase growth method such as a sputtering method.
[0037]
Photoelectric conversion layer
The photoelectric conversion layer 5 is preferably composed of single crystal silicon, microcrystalline silicon, or amorphous silicon having a pn junction or a pin junction, preferably a pin junction. The pn junction and the pin junction can be formed by adding a predetermined impurity when forming the photoelectric conversion layer.
[0038]
Hereinafter, a photoelectric conversion layer in which an n-type semiconductor layer, a photovoltaic layer (i layer), and a p-type semiconductor layer each formed of amorphous silicon or microcrystalline silicon will be described.
[0039]
The impurity for forming the p-type semiconductor layer is preferably B, and its content is 10¹⁷-10²⁰atoms / cm^ThreeIt is preferable that If the impurity content is too small or too large, the energy conversion efficiency is lowered.
[0040]
The impurity for forming the n-type semiconductor layer is preferably P, and its content is 10¹⁷-10²⁰atoms / cm^ThreeIt is preferable that If the impurity content is too small or too large, the energy conversion efficiency is lowered.
[0041]
The thickness of each layer is not particularly limited, but is preferably 5 to 40 nm for the p-type semiconductor layer, preferably 100 nm to 20 μm for the i layer, and preferably 5 to 40 nm for the n-type semiconductor layer.
[0042]
Such a photoelectric conversion layer is usually preferably formed by a plasma CVD method. The plasma in the plasma CVD method may be either direct current or alternating current, but preferably alternating current plasma is used. AC plasma can be used at frequencies from several hertz to several gigahertz.
[0043]
The p-type semiconductor layer is made of SiH as a raw material._Four, H₂, B₂H₆Etc., and the flow ratio B according to the target impurity content₂H₆/ SiH_FourThe insulating substrate temperature is room temperature to 450 ° C., preferably 200 to 300 ° C., the operating pressure is 0.01 to 10 Torr, the input power is 10 to 2000 W (frequency 10).⁶-10⁹Hz).
[0044]
i layer is SiH_Four, H₂Etc., each having a flow rate of 1 to 2000 sccm, an insulating substrate temperature of room temperature to 450 ° C., preferably 260 to 380 ° C., an operating pressure of 0.01 to 10 Torr, and an input power of 10 to 2000 W.
[0045]
The n-type semiconductor layer is made of SiH as a raw material._Four, H₂, PH_ThreeEtc., and the flow ratio PH according to the target impurity content_Three/ SiH_FourAnd the insulating substrate temperature is room temperature to 450 ° C., preferably 250 to 350 ° C., the operating pressure is 0.01 to 10 Torr, and the input power is 10 to 2000 W.
[0046]
Transparent electrode
The constituent material of the transparent electrode 6 is not particularly limited, but tin oxide, ITO (indium tin oxide), and ZnO are preferable because of their good transparency and conductivity. Although the thickness of a transparent electrode is not specifically limited, Usually, it is preferable to set it as 10-100 nm. The transparent electrode composed of the above materials is usually formed by a vapor phase growth method such as a sputtering method.
[0047]
Interlayer insulation layer, separator insulation layer
The material constituting the interlayer insulating layer 9 and the separator insulating layer 10 in the illustrated example is not particularly limited as long as it has insulating properties and can form the illustrated structure, but an insulating resin is usually used. preferable. As the insulating resin, for example, urethane resin, phenoxy resin, and the like are preferable. The interlayer insulating layer 9 and the separator insulating layer 10 may be made of the same material or different materials.
[0048]
The thickness of the interlayer insulating layer 9 is preferably 5 to 40 μm, and the thickness of the flat portion of the separator insulating layer 10 is preferably 5 to 10 μm.
[0049]
The interlayer insulating layer and the separator insulating layer may be usually formed by a coating method such as screen printing. The interlayer insulating layer 9 and the separator insulating layer 10 in the illustrated example are usually formed by the following procedure. First, after the photoelectric conversion layer 5 is formed, the interlayer insulating layer 9 is formed in a predetermined pattern by screen printing or the like. Subsequently, after forming the transparent electrode 6 on the interlayer insulation layer 9, the groove | channel which penetrates the transparent electrode 6, the interlayer insulation layer 9, the photoelectric converting layer 5, and the lower electrode 4 is formed by laser processing, for example. The laminated body from the lower electrode 4 to the transparent electrode 6 is divided by this groove and separated into cell units. Next, a separator insulating layer 10 is formed in a predetermined pattern on the transparent electrode 6 by screen printing or the like. At this time, the insulating material penetrates into the groove, and the separator portion 101 is formed.
[0050]
The interlayer insulating layer 9 is provided in order to prevent the transparent electrode 6 and the lower electrode 4 from being short-circuited when the separator portion 101 is formed, but also has a function of improving the breakdown voltage of the solar cell. For example, if a minute defect or inhomogeneity exists in the photoelectric conversion layer 5, a short circuit may occur between the lower electrode 4 and the transparent electrode 6 at that position. Since a relatively high capacitor is formed, it is possible to prevent such breakdown.
[0051]
Note that the interlayer insulating layers 9A and 9B and the separator insulating layers 10A and 10B shown in FIG. 3 may be formed in the same thickness as the interlayer insulating layer 9 and the separator insulating layer 10 shown in FIG.
[0052]
Collection / wiring electrode, connecting conductor, internal electrode, external electrode
The constituent material of the collection / wiring electrode 11 is not particularly limited, but it is usually preferable to use Ag. The thickness of the collecting / wiring electrode is preferably 5 to 10 μm.
[0053]
The collecting / wiring electrode may be usually formed by a coating method such as screen printing. In the illustrated example, the collecting / wiring electrode 11 is usually formed by the following procedure. First, after the separator insulating layer 10 is formed, the collecting / wiring electrodes 11 are formed in a predetermined pattern by screen printing or the like. Next, in a region where the interlayer insulating layer 9 does not exist, the collection / wiring electrode 11 is drilled by, for example, laser processing, and a hole reaching the lower electrode 4 through the transparent electrode 6 and the photoelectric conversion layer 5 is formed. During the drilling, the constituent material of the collecting / wiring electrode 11 is melted and penetrates into the hole to form the connection conductor 12.
[0054]
Note that the connection conductor 12B shown in FIG. 3 can be formed in the same manner as the connection conductor 12 shown in FIG. Further, the internal electrodes 51A and 51B and the external electrodes 52A and 52B shown in FIG. 3 can be formed in a predetermined pattern by screen printing or the like, like the collecting / wiring electrode 11. The thickness of the internal electrode and the external electrode is preferably 5 to 10 μm.
[0055]
Sealing member
A resin film is preferable as the sealing member for suppressing mechanical damage, oxidation, corrosion, and the like. The resin film may be formed by coating or pasting. The sealing member is preferably provided at least on the surface on the transparent electrode 6 side, and more preferably provided on the back surface side of the insulating substrate 2.
[0056]
Hereinafter, an example of a method for forming a resin film by sticking will be described. In this example, a sealing member in which a buffer adhesive layer containing a thermosetting resin is provided on at least one surface of a resin base material having translucency and heat resistance is used.
[0057]
The resin base material has a glass transition point Tg of 65 ° C. or higher, a heat resistant temperature (or continuous use temperature) of 80 ° C. or higher, or a resin film that satisfies both of these and has translucency. preferable. Even if such a resin film is directly exposed to a light source such as sunlight to raise the temperature, the performance does not deteriorate.
[0058]
As a resin-made substrate having a glass transition point Tg of 65 ° C. or higher and / or a heat-resistant temperature of 80 ° C. or higher,
Polyethylene terephthalate film (Tg 69 ° C.), polyethylene naphthalate heat-resistant film (Tg 113 ° C.);
Ethylene trifluorochloride resin [PCTFE: Neofluon CTFE (Daikin Industries, Ltd.)] (heat-resistant temperature 150 ° C.), polyvinylidene fluoride [PVDF: Denka DX film (Denki Kagaku Kogyo)] (heat-resistant temperature 150 ° C .: Tg50 ℃), polyvinyl fluoride [PVF: Tedlar PVF film (manufactured by DuPont)] (heat-resistant temperature 100 ° C), and tetrafluoroethylene-perfluorovinyl ether copolymer [PFA: NEOFLON: PFA film (Daikin Kogyo Co., Ltd.)] (heat resistant temperature 260 ° C), tetrafluoroethylene-hexafluoropropylene copolymer [FEP: Toyoflon Film FEP type (manufactured by Toray Industries, Inc.)] (heat resistant temperature 200 ° C), tetrafluoride Ethylene-ethylene copolymer [ETFE: Tefzel ETFE film (DuPont) ) (Heat-resistant temperature 0.99 ° C.), aFleX film (manufactured by Asahi Glass Company, Limited: Tg83 ℃)] fluorine-based film comprising a fluoride copolymers and the like;
Polyacrylate film such as aromatic dicarboxylic acid-bisphenol copolymer aromatic polyester [PAR: casting (Elmec manufactured by Kaneka Chemical Co., Ltd.)] (heat-resistant temperature 290 ° C .: Tg 215 ° C.);
Sulfur-containing polymer films such as polysulfone [PSF: Sumilite FS-1200 (manufactured by Sumitomo Bakelite)] (Tg 190 ° C.), polyether sulfone [PES: Sumilite FS-1300 (Sumitomo Bakelite)] (Tg 223 ° C.);
Polycarbonate film [PC: Panlite (manufactured by Teijin Chemicals Ltd.)] (Tg 150 ° C.);
Functional norbornene resin [ARTON (manufactured by JSR)] (heat-resistant temperature 164 ° C .: Tg 171 ° C.);
Polymethyl methacrylate (PMMA) (Tg 93 ° C.);
Olefin-maleimide copolymer [TI-160 (manufactured by Tosoh Corporation)] (Tg 150 ° C. or higher), para-aramid [Aramika R: manufactured by Asahi Kasei Co., Ltd.] (heat resistant temperature 200 ° C.), fluorinated polyimide (heat resistant temperature 200 ° C. or higher), polystyrene (Tg90 ° C), polyvinyl chloride (Tg70-80 ° C), cellulose triacetate (Tg107 ° C)
Etc.
[0059]
Among these, the polyethylene naphthalate heat-resistant film (Tg 113 ° C.) has a heat resistance (Tg), a heat resistance during long-term use, a Young's modulus (stiffness), a breaking strength, a heat shrinkage rate, and an oligomer as compared with a polyethylene terephthalate film. Excellent performance in terms of low properties, gas barrier properties, hydrolysis resistance, water vapor transmission rate, thermal expansion coefficient, physical properties deterioration due to light, etc. In addition, breaking strength and heat resistance compared to other polymers It is preferable because it is excellent in terms of overall balance such as dimensional stability, moisture permeability, and cost.
[0060]
The glass transition point Tg of the resin base material is preferably 65 ° C. or higher, more preferably 70 ° C. or higher, further preferably 80 ° C. or higher, and particularly preferably 110 ° C. or higher. The upper limit of Tg is not particularly limited, but is usually about 130 ° C. The heat-resistant temperature or continuous use temperature is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 110 ° C. or higher. The higher the heat-resistant temperature or the continuous use temperature, the better. The upper limit is not particularly limited, but is usually about 250 ° C.
[0061]
The thickness of the resin base material may be appropriately determined according to the structure of the solar cell, the strength required for the resin base material, the bending rigidity, and the like, but is usually 5 to 100 μm.
[0062]
In addition, it is preferable that the translucency of a resin base material is a grade which permeate | transmits 70% or more of the light of visible region, especially 80% or more.
[0063]
The buffer adhesive layer preferably contains a thermosetting resin component and an organic peroxide before thermocompression bonding.
[0064]
As the thermosetting resin component, an ethylene-vinyl acetate copolymer [EVA (vinyl acetate content is about 15 to 50%)] is preferable.
[0065]
Examples of the organic peroxide include 2,5-dimethylhexane-2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3; di-t -Butyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; dicumyl peroxide; α, α'-bis (t-butylperoxyisopropyl) benzene; n-butyl- 4,4-bis (t-butylperoxy) valerate; 2,2-bis (t-butylperoxy) butane; 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane; t-Butylperoxybenzate; benzoyl peroxide can be used. These may be used alone or in combination of two or more, and the blending ratio when used in combination is arbitrary. The amount of the organic peroxide used with respect to 100 parts by weight of the thermosetting resin component is preferably 10 parts by weight or less, more preferably 0.5 to 6 parts by weight.
[0066]
The thickness of the buffer adhesive layer may be appropriately determined according to the structure of the solar cell and the use environment, but is preferably 3 to 500 μm, more preferably 3 to 50 μm, and still more preferably 10 to 40 μm. If the buffer adhesive layer is too thin, the buffer effect is insufficient. On the other hand, if the buffer adhesive layer is too thick, the light transmittance is lowered, and burrs are likely to occur during punching. However, since the buffer adhesive layer is far more light transmissive than the resin base material, it may be no problem to increase the thickness to about 10 mm when used under high illuminance such as outdoors.
[0067]
As means for providing the buffer adhesive layer on the resin substrate, known means such as coating or extrusion coating can be used.
[0068]
The buffer adhesive layer may be embossed. When the sealing member is laminated on the solar cell, if the embossing is performed so that a bubble escape path is formed, the mixture of bubbles is reduced.
[0069]
Next, an example of a method for forming a resin film by coating will be described.
[0070]
The resin film formed by the application method is slightly inferior in terms of flatness, weather resistance, etc. compared to the resin film formed by pasting, but it is used when it is incorporated in equipment or used mainly indoors. Is no problem. In the coating method, since the laminating step and the subsequent flattening step that are necessary in the above-described sticking method can be omitted, the manufacturing cost can be reduced.
[0071]
The resin used in this case is preferably one having excellent transparency and little discoloration due to aging and light deterioration, and a thermosetting resin is particularly preferable. As the thermosetting resin, for example, a fluorine resin, polyurethane, polyester, epoxy resin, or phenoxy resin can be used.
[0072]
The resin coating film may be formed by a screen printing method, a spin coating method, or the like.
[0073]
Other electronic components
The present invention is particularly effective when applied to a solar cell, but even other electronic components have internal electrodes and external electrodes as described above, that is, one of through holes provided in an insulator. An internal electrode constituting a part of the internal circuit is formed on the side of the through hole by a coating method, and an external electrode for electrically connecting to the outside of the component is formed on the other side of the through hole by the coating method. Any type can be applied, and even in that case, the same effect as that obtained when applied to a solar cell can be obtained. Examples of such electronic components include multilayer electronic components such as chip capacitors and chip inductors.
[0074]
【Example】
A solar cell having the structure shown in FIGS. 3 and 4 was produced by the following procedure.
[0075]
As the insulating substrate 2, a polyethylene naphthalate (PEN) film (manufactured by Teijin, trade name Neotex, melting point 273 ° C., glass transition point 113 ° C.) having a length of 360 mm, a width of 460 mm and a thickness of 75 μm was used.
[0076]
First, in order to reinforce the insulating substrate 2, a silicon oxide layer having a thickness of 0.8 μm was formed on the entire surface of the insulating substrate 2 by electron beam evaporation.
[0077]
Next, a lower electrode 4 made of Al having a thickness of 0.3 μm was formed on the silicon oxide layer by sputtering, and further a diffusion prevention layer made of stainless steel having a thickness of 5 nm was formed thereon.
[0078]
Next, the photoelectric conversion layer 5 was formed on the diffusion prevention layer by the following procedure. First, an n-type microcrystalline silicon layer was formed to a thickness of 20 nm by plasma CVD. At that time, the source gas and its flow rate are
PH_Three+ H₂Mixed gas (PH_Three/ H₂= 0.2%): 30 sccm,
SiH_Four: 4 sccm,
H₂: 750sccm
And other conditions are:
Insulating substrate temperature: 300 ° C
Operating pressure: 1 Torr,
Input power: 100W (13.56MHz)
It was. Subsequently, an i-type amorphous silicon layer was formed to a thickness of 600 nm by plasma CVD. At that time, the source gas and its flow rate are
SiH_Four: 50 sccm,
H₂: 500sccm
And other conditions are:
Insulating substrate temperature: 260 ° C.
Operating pressure: 1 Torr,
Input power: 100W (13.56MHz)
It was. Subsequently, a p-type microcrystalline silicon layer was formed to a thickness of 20 nm by plasma CVD. At that time, the source gas and its flow rate are
B₂H₆+ H₂Mixed gas (B₂H₆/ H₂= 0.2%): 30 sccm,
SiH_Four: 5 sccm,
H₂: 950sccm
And other conditions are:
Insulating substrate temperature: 280 ° C
Operating pressure: 1 Torr,
Input power: 200W (13.56MHz)
It was.
[0079]
Next, a urethane insulating resin composition is printed on the photoelectric conversion layer 5 by a screen printing method in a predetermined pattern, and then left standing in an oven at 160 ° C. for 10 minutes to be cured, and an interlayer insulation having a thickness of 20 μm. Layers 9, 9A and 9B were used.
[0080]
Next, a transparent electrode 6 having a thickness of 60 nm was formed by sputtering in an Ar atmosphere using ITO (indium tin oxide) as a target.
[0081]
Next, grooves were formed by laser scribing, and a urethane insulating resin composition was screen-printed thereon to form separator insulating layers 10, 10A, and 10B having a thickness of 10 μm and having separator portions 101, 101A, and 101B, respectively. .
[0082]
Next, through holes 40A and 40B having a diameter of 100 μm were formed by mechanical processing.
[0083]
Next, the Ag paste was screen-printed and dried and cured to form the collecting / wiring electrode 11 (thickness 6 μm) and the connecting conductors 12 and 12B.
[0084]
Next, external electrodes 52A and 52B (thickness 6 μm) were formed by screen-printing Cu paste and drying and curing. When the Cu paste used for external electrode formation was observed with a scanning electron microscope after drying and curing, Cu particles having a particle size in the range of 5 to 15 μm accounted for 90% by volume or more of the entire Cu particles. In addition, this Cu paste has a sheet resistance after drying and curing of 60 mΩ / □.
[0085]
Next, the Ag paste was screen-printed and dried and cured to form the internal electrodes 51A and 51B (thickness 6 μm), thereby obtaining a solar cell sample. When the Ag paste used for forming the internal electrode was observed with a scanning electron microscope, the Ag particles having a particle size in the range of 0.1 to 4 μm accounted for 90% by volume or more of the total Ag particles. In addition, this Ag paste has a sheet resistance after drying and curing of 0.1 mΩ / □ or less.
[0086]
For comparison, a solar cell sample in which an external electrode was formed after the internal electrode was formed was also produced.
[0087]
About these samples, the optical microscope photograph of the cross section near a through hole was image | photographed. A photograph of a sample in which an external electrode is formed after the formation of the internal electrode is shown in FIG. 6, and a photograph of a sample in which the internal electrode is formed after the formation of the external electrode is shown in FIG. 5 and 6, the base body exists in the left-right direction of the central portion, and a through hole penetrating in the vertical direction exists substantially at the center of the base body. The internal electrode is applied from the upper side of the substrate, and the external electrode is applied from the lower side of the substrate. In the figure, coarse particles having high brightness are large-diameter particles constituting the external electrode, and fine particles having slightly low brightness are small-diameter particles constituting the internal electrode. In the sample in which the external electrode is formed after the internal electrode is formed, as shown in FIG. 6, the small diameter conductive particles are almost independent from each other near the inner wall surface of the through hole, and the large diameter conductive particles are near the central axis of the through hole. Exist. On the other hand, in the sample in which the internal electrode is formed after the external electrode is formed, as shown in FIG. 5, large-diameter conductive particles are near the inner wall surface of the through hole, and small-diameter conductive particles are near the central axis of the through hole and large. It exists between the conductive particles having a diameter.
[0088]
About these samples, conduction | electrical_connection between an internal electrode and an external electrode was investigated. As a result, in the sample in which the internal electrode was formed after the formation of the external electrode, no continuity failure was observed in all 21 measured cases, whereas in the sample in which the external electrode was formed after the formation of the internal electrode, 3 out of 21 samples A continuity failure was observed.
[0089]
【The invention's effect】
In the present invention, on one surface of the insulating substrate having a through hole, an internal electrode constituting at least a part of the internal circuit is provided, and on the other surface, an external electrode for electrically connecting to the outside is provided, In addition, the internal electrode and the external electrode are connected in the through hole. Then, conductive particles having a small particle size are used for the internal electrode, and conductive particles having a large particle size are used for the external electrode. As a result, the electrical resistance of the internal circuit can be reduced and the entry of static electricity from the outside can be suppressed, so that both characteristics and reliability can be improved. Also, if the external electrode containing large-diameter conductive particles is formed prior to the internal electrode containing small-diameter conductive particles, the contact state between the external electrode and the internal electrode in the through hole becomes good, Properties and reliability are further improved.
[Brief description of the drawings]
FIGS. 1A and 1B are cross-sectional views in the vicinity of a through hole provided in an insulating substrate.
FIGS. 2A and 2B are cross-sectional views in the vicinity of a through hole provided in an insulating substrate.
FIG. 3 is a cross-sectional view showing the vicinity of both ends of a solar cell.
FIG. 4 is a cross-sectional view showing the vicinity of the center of the solar cell.
FIG. 5 is a drawing-substituting photograph showing the particle structure and an optical micrograph showing a cross section near the through hole of the solar cell.
FIG. 6 is a drawing-substituting photograph showing the particle structure and an optical micrograph showing a cross section near the through hole of the solar cell.
[Explanation of symbols]
2 Insulating substrate
4 Lower electrode
5 Photoelectric conversion layer
6 Transparent electrodes
9, 9A, 9B Interlayer insulation layer
10, 10A, 10B Separator insulation layer
101, 101A, 101B Separator part
11 Collection and wiring electrodes
12, 12B Connecting conductor
40A, 40B Through hole
51A, 51B Internal electrode
52A, 52B External electrode
51a Small diameter conductive particles
52a Large diameter conductive particles

Claims (6)

An electron having an internal electrode on one surface side of the insulating substrate and an external electrode on the other surface side, and the internal electrode and the external electrode are in contact with each other in a through hole provided in the insulating substrate Parts,
An electronic component in which the internal electrode contains conductive particles having a relatively small diameter and the external electrode contains conductive particles having a relatively large diameter. The electronic component according to claim 1, wherein a region in which the large-diameter conductive particles and the small-diameter conductive particles are mixed exists in the through hole. The large-diameter conductive particles mainly exist near the inner wall surface of the through hole, and the small-diameter conductive particles exist near the central axis of the through-hole and between the large-diameter conductive particles. Electronic components. A solar cell having a lower electrode, a photoelectric conversion layer and a transparent electrode in this order on the surface of the insulating substrate,
The electronic component according to claim 1, wherein the internal electrode is electrically connected to the lower electrode or the transparent electrode, and the external electrode functions as an extraction electrode. A method for manufacturing the electronic component according to claim 1,
After printing the conductive paste containing the small-sized conductive particles, the internal electrode forming step for drying and curing, and after forming the conductive paste containing the large-sized conductive particles, the external electrode forming step for drying and curing. Manufacturing method of electronic components. The method for manufacturing an electronic component according to claim 5, further comprising the internal electrode forming step after the external electrode forming step.

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