JP5471097B2 - Bonding method of metal substrate and glass substrate - Google Patents

Description

  The present invention relates to a method for joining a metal substrate and a glass substrate, and more particularly, to a method for joining a metal substrate and a glass substrate using a sealing material.

  A glass substrate is used for various applications by taking advantage of its transparent property. Depending on the application, the glass substrate is used by being bonded to a metal substrate. A typical example thereof is a dye-sensitized solar cell.

  For example, a dye-sensitized solar cell having a structure shown in FIG. 1 is known. That is, in FIG. 1, this dye-sensitized solar cell has a structure in which a photoelectrode substrate 1 (negative electrode) and a counter electrode substrate 3 (positive electrode) face each other with an electrolyte solution 5 interposed therebetween. The peripheral portions of the electrode substrate 1 and the counter electrode substrate 3 are joined and sealed with a sealing material 7 so that the electrolyte solution 5 does not leak.

  In such a dye-sensitized solar cell, the photoelectrode substrate 1 is provided with a porous layer 1b of an oxide semiconductor such as titanium dioxide on a metal plate 1a such as an aluminum plate, and this porous layer 1b. A sensitizing dye (for example, Ru dye) 1c is adsorbed and supported on the surface. Further, the counter electrode substrate 3 has a transparent conductive film 3b such as ITO formed on the surface of the glass plate 3a, and further, a deposited film such as platinum or platinum is formed thereon as an electron reducing conductive layer 3c. The transparent conductive film 3b and the electron reducing conductive layer 3c function as an electrode layer.

  That is, in the above dye-sensitized solar cell, the dye 1c is excited by irradiation of visible light from the counter electrode substrate 3 side, and the excited electrons of the dye 1c are injected into the conduction band of the oxide semiconductor layer 1b. Then, it moves from the metal plate 1a to the counter electrode substrate 3 through an external load (not shown), is carried from the transparent conductive film 3b through the conductive layer 3c by ions in the electrolyte solution 5, and returns to the dye 1c. By repeating this, electric energy is extracted by an external load.

  By the way, in said dye-sensitized solar cell, the glass plate 3a which has the transparent conductive film 3b and the electron reducible conductive layer 3c on the surface in the metal plate 1a which has the oxide semiconductor layer 1b sensitized with the pigment | dye 1c on the surface. In general, this bonding is performed by heat sealing by sandwiching a sheet or film of a thermoplastic resin between the peripheral portions of both the substrates 3a and 1a. That is, by this, sealing can be performed simultaneously with the joining of the two substrates (the thermoplastic resin becomes the sealing material 7).

  However, as described above, when a metal substrate is bonded to a glass substrate by heat sealing, the linear expansion coefficients of the glass substrate and the metal substrate are greatly different. There is a problem that deformation occurs, and the glass substrate is damaged or a sealing failure occurs. For example, the linear expansion coefficient of an aluminum plate is 23 ppm / ° C, Zn is 33 ppm / ° C, Stainless steel (SUS304) is 17.3 ppm / ° C, Cu is 16.5 ppm / ° C, and iron is 10-12 ppm / ° C. On the other hand, the linear expansion coefficient of quartz glass is 0.5 ppm / ° C., Pyrex glass is 3.3 ppm / ° C., and blue plate glass having the largest linear expansion coefficient is 9 ppm / ° C. There is a considerable difference in the coefficient of linear thermal expansion.

  In general, it is known that bonding between a glass substrate and another substrate and sealing in a solar cell as described above are performed by laser welding (see Patent Documents 1 and 2). When joining substrates, there is no known joining means that is considered to prevent deformation due to a difference in linear expansion coefficient.

Japanese Patent Publication No. 5-75707 JP 2007-42460

  Accordingly, an object of the present invention is to provide a method capable of joining a glass substrate and a metal substrate without causing deformation due to a difference in thermal expansion.

According to the present invention, in a method of joining a metal substrate and a glass substrate through a sealing material made of a thermoplastic resin ,
The glass substrate is heated to raise the temperature of the glass substrate, and in this state, the glass substrate is pressed against the surface of the metal substrate on which the sealing material is disposed, and at the same time, the metal substrate is sealed with the seal. There is provided a method for joining a metal substrate and a glass substrate, characterized in that the metal substrate is heated to a temperature equal to or higher than the melting point of the stopper, and then the heating of the metal substrate is stopped to selectively cool the metal substrate.

In the joining method of the present invention,
(1) The metal substrate is heated by high-frequency heating means,
(2) cooling the metal substrate with a refrigerant used for cooling the high-frequency heating means;
(3) heating the metal substrate selectively with respect to a portion where the sealing material is disposed;
(4) As the glass substrate, a glass electrode substrate in which an electrode layer composed of a transparent conductive film and an electron reducing conductive layer is formed on one surface of the glass plate is used, and the surface of the metal plate is used as the metal substrate. A metal photoelectrode substrate on which a semiconductor porous layer sensitized with a dye is formed, and the glass electrode substrate and the metal photoelectrode substrate are arranged so that the electrode layer and the semiconductor porous layer face each other. And bonding the periphery of the glass electrode substrate and the metal photoelectrode substrate through the sealing material,
Is preferred.

  In the bonding method of the present invention, the bonding between the glass substrate and the metal substrate is performed by using thermal welding of a sealing material (for example, a heat-sealable thermoplastic resin). The point is that the metal substrate is selectively cooled in a state where the glass substrate and the metal substrate are pressure-bonded with the molten sealing material interposed therebetween. That is, by cooling the metal substrate in this way, the temperature of the metal substrate drops sharply compared to the glass substrate, since the thermal conductivity of the metal substrate is significantly higher than the glass substrate, As a result, when the molten sealing material solidifies, the temperature of the metal substrate having a large thermal expansion coefficient is considerably lower than the temperature of the glass substrate having a small thermal expansion coefficient. Therefore, as a result of such a temperature difference, in the state where the sealing material is solidified, the thermal expansion difference between the metal substrate and the glass substrate is effectively relaxed (after the sealing material is solidified). The shrinkage between the metal substrate and the glass substrate during normal temperature is almost the same), and seal breakage (deformation or breakage of the sealing material) due to this thermal expansion difference is effectively prevented, and also due to the thermal expansion difference Therefore, it is possible to effectively prevent warping of the metal substrate.

Moreover, in this invention, it is preferable to heat a metal substrate by a high frequency heating means. The high-frequency heating means performs heating by induction heating with a high-frequency current flowing through the coil. The heating means is provided with a cooling pipe, and a coolant such as water is always supplied to the cooling pipe. Thus, the coil itself is prevented from being heated. That is, when such a high-frequency heating means is used, selective cooling of the metal substrate can be started immediately using the refrigerant circulated inside the high-frequency heating means. This is because when the power is turned off, the temperature of the high-frequency heating coil immediately decreases to about room temperature, so that the refrigerant circulating in the vicinity of the coil immediately contributes to cooling of the metal substrate.
Further, the use of the high-frequency heating means makes it possible to selectively heat the portion of the metal substrate on which the sealing material is provided, which is advantageous in terms of thermal efficiency.

  Furthermore, in the present invention, since the glass substrate is heated in advance prior to the heating of the metal substrate, the heating conditions for the metal substrate can be reduced. That is, it is necessary to heat the metal substrate so that the sealing material disposed between the metal substrate and the glass substrate is melted, but by heating the glass substrate in advance, Can be reduced.

  Such a joining method of the present invention is particularly suitably applied to a production process of a dye-sensitized solar cell. For example, as the glass substrate, an electrode comprising a transparent conductive film and an electron reducing conductive layer on one surface of a glass plate. A glass electrode substrate in which a layer is formed, and a metal photoelectrode substrate in which a semiconductor porous layer sensitized with a dye is formed on the surface of the metal plate as the metal substrate, and a sealing material Thus, the present invention can be advantageously applied to the bonding of these electrode substrates.

It is a sectional side view which shows the schematic structure of the dye-sensitized solar cell to which the joining method of this invention is applied suitably. It is a figure which shows the process of the joining method of this invention. In Example 1, it is a figure which shows the temperature change of each board | substrate when a metal substrate and a glass substrate are joined.

The present invention will be described below based on specific examples shown in the accompanying drawings.
Referring to FIG. 2 showing the process of the bonding method of the present invention, the glass substrate 20 is held by a predetermined jig 21, and a heater 23 is set on the jig 21 to heat the glass substrate 20. It has come to be able to do.
On the other hand, a metal substrate 25 is disposed below the glass substrate 20 held by the jig 21 as described above, and a high-frequency heating member 27 is disposed below the metal substrate 25. .
A sealing material 29 is placed on the upper surface of the metal substrate 25.

  The sealing material 29 joins the glass substrate 20 and the metal substrate 25 by thermal welding, and a film or sheet of a thermoplastic resin is usually used. The thermoplastic resin may be any thermoplastic resin as long as heat welding is possible. For example, low-density polyethylene, high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, Or a polyolefin resin such as a random or block copolymer of α-olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene; ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer , Ethylene-vinyl compound copolymer resins such as ethylene-vinyl chloride copolymer; styrene resins such as polystyrene, acrylonitrile-styrene copolymer, ABS, α-methylstyrene-styrene copolymer; polyvinyl alcohol, polyvinylpyrrolidone , Polyvinyl chloride, polyvinylidene chloride, vinyl chloride-salt Vinylidene chloride copolymers, vinyl resins such as polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethyl methacrylate; polyamides such as nylon 6, nylon 6-6, nylon 6-10, nylon 11 and nylon 12 Resin; Polyester resin such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate; Polyphenylene oxide; Cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; Starch such as oxidized starch, etherified starch and dextrin; However, polyethylene terephthalate and polyolefin are preferable from the viewpoint of cost, strength, heat resistance, and the like.

  Moreover, the shape and thickness of the sealing material 29 can be set appropriately according to the use of the joined body of the glass substrate 20 and the metal substrate 25. For example, a solar cell having a structure as shown in FIG. When used as an electrode, the sealing material 29 has a frame shape and has a structure in which the glass substrate 20 and the metal substrate 25 are joined at the peripheral edge. In this case, the sealing material 29 is surrounded by the sealing material 29. Since the inner region is filled with the electrolytic solution, the thickness of the sealing material 29 after joining is normally set to about 10 to 20 μm.

Referring also to FIG. 3 showing the temperature change of each substrate in the bonding performed in Example 1 described later, in the bonding method of the present invention, first, the glass substrate 20 is heated by the heater 23. The glass substrate 20 is heated to a temperature close to the melting point of the sealing material 29 and maintained. Although this temperature can be set to a temperature higher than the melting point of the sealing material 29, since the melting of the sealing material 29 is performed by heating the metal substrate 25, the glass substrate 20 is heated to an unnecessarily high temperature. It is not necessary to heat, and it is preferable to heat and maintain the glass substrate 20 at a temperature lower than the melting point of the sealing material 29, for example, a temperature range lower by about 10 to 60 ° C. than the melting point of the sealing material 29.
Moreover, if the heating temperature of a glass substrate is below the temperature which a sealing material solidifies, it also becomes possible to attach the jig | tool heated after adhesion | attachment. In particular, when the present invention is applied to the joining of electrode substrates in a dye-sensitized solar cell as shown in FIG. 1, five layers of electrolytes are likely to cause performance degradation due to heat on the surface of the glass plate 3a. When (for example, a solid electrolyte) is provided, bonding is performed in a state in which such an electrolyte layer 5 is formed. Therefore, from the viewpoint of preventing performance degradation of the electrolyte layer 5, the glass substrate 20 (glass The temperature of the plate 3a) is preferably kept at a temperature below the melting point of the sealing material 29.

In addition, by heating the glass substrate 20 in advance as described above, the sealing material 29 can be melted by making the heating conditions of the metal substrate 25 gentle.
Moreover, by heating the whole glass substrate, the thermal expansion of the glass substrate can be increased, and the amount of thermal expansion of the aluminum substrate that is selectively heated can be brought close to.

  In a state where the glass substrate 20 is heated to a predetermined temperature, the power supply of the heater 23 is turned off (if the heating temperature is lower than the solidification temperature of the sealing material, it may remain ON), and the jig 21 is lowered. The glass substrate 20 is pressed against the surface of the metal substrate 25 disposed below. This pressure is set in such a range that when the sealing material 29 is melted, an appropriate thickness is maintained in the melt. That is, when the pressure is too low, the pressure bonding is insufficient, so that the bonding strength is likely to be lowered. Also, when the pressure is too high, the melt of the sealing material 29 diffuses, This is because the amount of the sealing material 29 per unit area is lowered, and as a result, the bonding strength is also lowered. Therefore, the specific range of the pressing force varies depending on the degree of heating of the metal substrate 25 in the next process and the flow characteristics of the melt of the sealing material 29, and cannot be specified in general. When the length is 60 mm square and the seal width is 5 mm, the pressing load needs to be 20 kg or more.

  When the glass substrate 20 is pressed against the surface of the metal substrate 25 with the sealing material 29 interposed therebetween as described above, the power of the heater 23 is turned off. However, since the heating of the metal substrate 25 is started immediately, such a temperature drop is not a problem.

  The metal substrate 25 is heated by the high-frequency heating member 27 provided below the metal substrate 25 under the pressure as described above, whereby the metal substrate 25 is heated to a temperature equal to or higher than the melting point of the sealing material 29. The temperature of the glass substrate 20 rises together with the metal substrate 25 due to heat transfer from the metal substrate 25.

By such heating, the sealing material 29 between the glass substrate 20 and the metal substrate 25 is heated and melted at a temperature equal to or higher than its melting point, and is in close contact with the glass substrate 20 and the metal substrate 25 in a molten state. It becomes.
In this case, preheating the glass substrate 20 is suitable for lowering the output conditions of the high-frequency heating member 27 and heating the sealing material 29 to a temperature equal to or higher than the melting point to bring it into a molten state.

  Moreover, since the heating of the metal substrate 25 is performed in order to heat the sealing material 29 to be in a molten state, depending on the shape of the sealing material 29, the portion where the sealing material 29 is provided is provided. However, it is preferable from the viewpoint of energy saving or the like to dispose the high-frequency heating member 27 and selectively heat the portion.

  When the sealing material 29 reaches a temperature equal to or higher than the melting point and is sufficiently melted, the power of the high-frequency heating member 27 is turned off, and the heating of the metal substrate 25 is stopped. At this time, the pressing of the glass substrate 20 to the metal substrate 25 may be released at the same time as the heating of the metal substrate 25 is stopped, but generally, with a slight time lag (usually about 2 to 3 seconds). It is preferable to release the pressure. That is, the temperature of the metal substrate 25 and the glass substrate 20 decreases at the same time as the heating of the metal substrate 25 is stopped, but the molten sealing material 29 is not immediately solidified, and is maintained in a molten state for a certain time. . Therefore, the bonding force by the sealing material 29 can be increased by applying a pressing force even after the heating is stopped.

In the present invention, it is important to selectively cool the metal substrate 25 after heating the metal substrate 25 as described above and then stopping the heating of the metal substrate 25.
That is, after the heating of the metal substrate 25 is stopped, for example, when both the metal substrate 25 and the glass substrate 20 are cooled by being allowed to cool, the temperature difference between the metal substrate 25 and the glass substrate 20 remains small, and both the substrates 20, 25 are kept. In this process, the molten sealing material 29 is solidified. Therefore, in this case, since the thermal expansion coefficient of the metal substrate 25 is considerably larger than that of the glass substrate 20, the shrinkage amount of the metal substrate 25 and the shrinkage amount of the glass substrate 20 when the sealing material is solidified are obtained. As a result, a large stress due to the difference in thermal expansion coefficient is generated in the solidified sealing material 29, resulting in deformation or breakage of the sealing material 29 or deformation of the metal substrate 25. End up.

  However, in the present invention, since the metal substrate 25 is selectively cooled after the heating of the metal substrate 25 is stopped, the temperature of the metal substrate 25 is greatly reduced as compared with the glass substrate 20 as shown in FIG. To do. That is, the amount of shrinkage of the metal substrate 20 between the time when the sealing material is solidified and at room temperature is almost the same as the amount of shrinkage of the glass substrate, and the difference in thermal expansion between the metal substrate 25 and the glass substrate 25 is effective. It will be relaxed. As a result, deformation or breakage of the sealing material 29 or warpage of the metal substrate 25 can be effectively prevented.

  In the present invention, in the above-described example, the high-frequency heating member 27 is used as a means for heating the metal substrate 25. Of course, like the glass substrate 20, such a heating means is a normal one. A heater can also be used. However, the use of the high-frequency heating member 27 has an advantage that the selective cooling of the metal substrate 25 can be performed very quickly. That is, a coolant such as water is circulated in the high-frequency heating member 27 in order to prevent the high-frequency coil itself from being heated. For this reason, when the power of the high-frequency heating member 27 is turned off and the heating is stopped, the refrigerant contributes to cooling of the metal substrate 25 (the temperature of the high-frequency coil returns to room temperature almost simultaneously with the stop of energization) The metal substrate 25 can be selectively cooled quickly without using any special cooling means.

  The glass substrate 20 may be allowed to cool while the metal substrate 25 is selectively cooled. This is because the thermal conductivity of the glass substrate 20 is smaller than that of the metal substrate 25, so that the temperature does not drop suddenly due to cooling.

  Further, the selective cooling of the metal substrate 25 may be performed until the sealing material 29 is completely solidified. After the sealing material 29 is completely solidified, the selective cooling may be performed as it is, or high-frequency heating is performed. The member 27 may be removed and switched to simple cooling. Further, if the sealing material 29 is completely solidified, the glass substrate 20 can be rapidly cooled by water cooling or the like.

The above-described joining method of the present invention is suitably applied to joining of the glass electrode substrate 3 and the photoelectrode substrate 1 (metal electrode substrate) in the dye-sensitized solar cell having the structure shown in FIG. That is, the glass electrode substrate 1 may be used as the glass substrate described above, the photoelectrode substrate 1 may be a metal substrate, and both substrates may be bonded using a sealing material.
In particular, in the dye-sensitized solar cell of FIG. 1, an aluminum substrate is used as the metal substrate 1a. However, the difference in thermal expansion coefficient between the aluminum substrate and the glass substrate is extremely large, and the deformation of the sealing material 7 Although breakage (causing leakage of the electrolyte) or warping of the aluminum metal substrate 1a is likely to occur, such inconvenience can be effectively avoided by applying the present invention.

The invention is illustrated by the following examples.
Example 1
A water-cooled 5-turn heating coil was used for the high-frequency heating member 27. The heating coil is connected to a 50 kHz high frequency power source (not shown). An aluminum substrate having a thickness of 0.28 mm and a polypropylene sealing material having a thickness of 0.05 mm are placed on the high-frequency heating member 27, and a glass substrate having a thickness of 1.1 mm is attached to the jig 21 heated by the heater 23. Preheated to 100 ° C.
Thereafter, the heater, jig, and glass substrate were lowered and pressed against the aluminum substrate and the sealing material with a load of 20 kg. And it heated for 5 second with the output of about 1.2 kW by the high frequency, and immediately after that, it rapidly cooled from the aluminum substrate side, and the solar cell bonded was created.
The heating temperature curves of the glass substrate and the aluminum substrate at this time are shown in FIG. The deflection of the solar cell cooled to room temperature was about 90 μm, and there was no problem. Further, there was no problem with sealing strength and leakage after filling with electrolyte.

(Comparative Example 1)
In the same apparatus as in Example 1, when the heater was not heated, that is, when the glass substrate was heated at high frequency in a room temperature state, the high frequency heating conditions were not bonded under the same conditions as in Example 1. Moreover, although the high-frequency heating conditions were changed and the heating temperature was increased and bonding was performed, sufficient seal strength could not be obtained.

1: Photoelectrode substrate 1a: Metal plate 1b: Porous semiconductor layer 1c: Sensitizing dye 3: Glass electrode substrate 3a: Glass plate 3b: Transparent conductive film 3c: Electron reducing conductive layer 5: Electrolyte solution 7: Sealing Material 20: Glass substrate 21: Jig 23: Heater 25: Metal substrate 27: High-frequency heating member 29: Sealing material

Claims (5)

In a method of joining a metal substrate and a glass substrate via a sealing material made of thermoplastic resin ,
The glass substrate is heated to raise the temperature of the glass substrate, and in this state, the glass substrate is pressed against the surface of the metal substrate on which the sealing material is disposed, and at the same time, the metal substrate is sealed with the seal. A method of joining a metal substrate and a glass substrate, wherein the metal substrate is heated to a temperature equal to or higher than the melting point of the stopper, and then the heating of the metal substrate is stopped and the metal substrate is selectively cooled.   The joining method according to claim 1, wherein the metal substrate is heated by a high-frequency heating means.   The bonding method according to claim 2, wherein the cooling of the metal substrate is performed by a refrigerant used for cooling the high-frequency heating means.   The bonding method according to claim 1, wherein heating of the metal substrate is selectively performed on a portion where the sealing material is disposed.   As the glass substrate, a glass electrode substrate in which an electrode layer composed of a transparent conductive film and an electron reducing conductive layer is formed on one surface of the glass plate is used, and as the metal substrate, a pigment is applied to the surface of the metal plate. Using a metal photoelectrode substrate on which a sensitized semiconductor porous layer is formed, the glass electrode substrate and the metal photoelectrode substrate are arranged so that the electrode layer and the semiconductor porous layer face each other. The bonding method according to any one of claims 1 to 4, wherein a peripheral portion of the glass electrode substrate and the metal photoelectrode substrate is bonded through the sealing material.

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