Circuit board for bypass diode, bypass diode device, and solar cell module

Abstract

A circuit board (11) for a bypass diode according to the present disclosure has a ceramic substrate (111) and a conductor (112). The conductor (112) is, in a single-piece configuration, disposed on a main surface of the ceramic substrate (111). The conductor (112) has a first electrode part (112a) and a second electrode part (112b). The first electrode part (112a) has mounted thereto a bypass diode (12) and is configured to electrically connect to the bypass diode (12). The second electrode part (112b) is a region of the conductor (112) excluding the first electrode part (112a).

Description

Circuit board for bypass diode, bypass diode device and solar cell module

[0001] The present disclosure relates to a circuit board for a bypass diode, a bypass diode device, and a solar cell module.

[0002] In recent years, solar power generation has become increasingly popular as a renewable energy source. Current solar cell modules usually have a junction box on the backside.

[0003] The junction box contains bypass diodes that protect the solar cells by bypassing the current when a problem occurs, such as when the solar cell module is shaded (see, for example, Patent Document 1).

[0004] JP 2015-185784 A

[0005] A circuit board for bypass diodes according to one aspect of the present disclosure includes a ceramic substrate and a conductor. The conductor is disposed as a single sheet on a main surface of the ceramic substrate. The conductor has a first electrode portion and a second electrode portion. The first electrode portion is an electrode on which a bypass diode is disposed and which electrically connects the bypass diode. The second electrode portion is a region of the conductor excluding the first electrode portion.

[0006] FIG. 1 is a cross-sectional view of a bypass diode device shown as an example of an embodiment. FIG. 2 is a cross-sectional view of a solar cell module shown as an example of an embodiment. FIG. 3 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 4 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 5 is a plan view of the circuit board for bypass diodes shown in FIG. 4. FIG. 6 is a diagram showing a configuration in which a third electrode portion and a fourth electrode portion are provided on the back surface of the circuit board for bypass diodes shown in FIG. 4. FIG. 7 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 8 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 9 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 10 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 11 is a cross-sectional view showing another aspect of a circuit board for bypass diodes. FIG. 12 is a schematic view of an automobile equipped with a solar cell module.

[0007] Hereinafter, a bypass diode circuit board according to an embodiment, and a bypass diode device and a solar cell module using the same will be described with reference to the drawings. Note that one aspect of the present disclosure is not limited to the specific embodiment described below. One aspect of the present disclosure includes various aspects as long as they are within the spirit or scope of the general inventive concept defined by the appended claims.

[0008] The above-mentioned prior art has room for improvement in terms of making a circuit including a junction box having a bypass diode smaller or thinner.

[0009] Therefore, there is a need for a technology that can overcome the above-mentioned problems and make circuits equipped with bypass diodes smaller and thinner.

[0010] 1 is a cross-sectional view of a bypass diode device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a solar cell module according to an embodiment of the present invention.

[0011] As shown in FIG. 1 , a bypass diode device 1 shown as an example of an embodiment includes a bypass diode circuit board 11 and a bypass diode 12 .

[0012] First, the bypass diode circuit board 11 will be described. The bypass diode circuit board 11 has a ceramic substrate 111 and a conductor 112. The conductor 112 is disposed as a single sheet on the main surface of the ceramic substrate 111. The conductor 112 has a first electrode portion 112a and a second electrode portion 112b.

[0013] The bypass diode circuit board 11 has a configuration in which the conductors 112 are simply arranged on the main surface of the ceramic substrate 111, so that the circuit including the bypass diodes 12 can be made small and thin.

[0014] The first electrode portion 112a of the conductor 112 is a portion (mounting portion) on which the bypass diode 12 is mounted. The first electrode portion 112a is an electrode for electrically connecting the bypass diode 12. The first electrode portion 112a is a member for fixing the bypass diode 12 to the ceramic substrate 111.

[0015] The second electrode portion 112b is basically a region of the conductor 112 excluding the first electrode portion 112a. A conductive member such as a connecting wire is connected to the second electrode portion 112b. The first electrode portion 112a and the second electrode portion 112b are electrically connected.

[0016] Since the conductor 112 is a single sheet on the main surface of the ceramic substrate 111, the first electrode portion 112a and the second electrode portion 112b constituting the conductor 112 have the same polarity. The first electrode portion 112a and the second electrode portion 112b have the same potential. In other words, the first electrode portion 112a and the second electrode portion 112b have the same polarity and potential.

[0017] On the conductor 112, between the first electrode portion 112a and the second electrode portion 112b, there may be a region where the bypass diode 12 is not mounted or where a conductive member such as a connecting wire is not arranged.

[0018] The conductor 112 being one piece means that it is in the form of one metal film, as shown in FIG.

[0019] The conductor 112 may have different thicknesses between the first electrode portion 112 a and the second electrode portion 112 b. The conductor 112 may have portions with different thicknesses at any location on the conductor 112 without specifying the first electrode portion 112 a or the second electrode portion 112 b.

[0020] When the conductor 112 has portions with different thicknesses, it becomes possible to adjust the height between the bypass diode 12 mounted on the first electrode portion 112a and the conductive member connected to the second electrode portion 112b. For example, this can be done when it is desired to align the height of the bypass diode 12 and the height of the conductive member or to reduce the difference between their heights.

[0021] The second electrode portion 112b serves as a conductor for passing current outside the bypass diode circuit board 11. The second electrode portion 112b serves as a conductor for taking in current from an external circuit to the bypass diode 12. When electrically connected, these are covered with organic resin 15 as shown in FIG.

[0022] A metal having high conductivity is preferable as the material of the conductor 112. Examples of the material of the conductor 112 include one selected from the group consisting of copper, tungsten, molybdenum, aluminum, iron, nickel, cobalt, solder (Sn—Pb), and precious metals.

[0023] The material of the conductor 112 preferably has a high thermal conductivity. In this case, copper or silver is suitable. A material that can be co-fired with the ceramic substrate 111 may be selected as the material of the conductor 112. The conductor 112 may be formed by baking the conductor 112 onto a pre-sintered ceramic substrate 111. When forming the conductor 112 by baking, it is preferable to use a metal-containing composition that can be fixed at a temperature lower than the sintering temperature of the ceramic substrate 111. When using a coating method or a printing method to form the metal-containing composition on the ceramic substrate 111, it is preferable to use a so-called paste-like composition in which a metal powder and an organic vehicle are mixed.

[0024] The shape of the ceramic substrate 111 can be selected arbitrarily depending on the design of the bypass diode device 1 and the solar cell module 2 to which the bypass diode device 1 is to be attached.

[0025] When viewed from above, the ceramic substrate 111 may have a basic shape such as a rectangle, a circle, an ellipse, or a polygon other than a rectangle.

[0026] When the basic shape of the ceramic substrate 111 is a rectangle, a circle, an ellipse, or a polygon other than a rectangle, the ceramic substrate 111 may have a recess or a protrusion on the corners or on the side between two corners of the ceramic substrate 111 having these shapes.

[0027] The material used for ceramic substrate 111 may be any material containing at least one selected from the group consisting of alumina, mullite, silicon nitride, aluminum nitride, silica, forsterite, and glass ceramics as a main component, because these materials can provide a ceramic substrate that exhibits excellent properties such as insulation, mechanical strength, moisture resistance, weather resistance, and chemical resistance.

[0028] The basic configuration of the bypass diode device 1 of the present disclosure is such that the bypass diode 12 is mounted on the conductor 112 .

[0029] The bypass diode 12 is fixed to the bypass diode circuit board 11 via a bonding material 121. As the bonding material 121, solder or a conductive adhesive is selected, but in terms of heat resistance, a conductive adhesive containing metal particles in an organic resin may also be selected.

[0030] 1 , in addition to the bypass diode 12, a first electrode member 13 is joined to the surface of the bypass diode 12. The first electrode member 13 is joined to the surface of the bypass diode 12 via, for example, a joining material 121.

[0031] In the bypass diode device 1 shown in FIG. 1, in addition to the bypass diode 12, a second electrode member 14 is joined to the second electrode portion 112b.

[0032] The bypass diode device 1 of the present disclosure is not limited to this. The bypass diode device 1 of the present disclosure may be configured such that the bypass diode 12 is mounted on the conductor 112.

[0033] The bypass diode 12 is a junction of a P-type semiconductor and an N-type semiconductor. In Fig. 1, the bypass diode 12 is mounted on the first electrode portion 112a of the conductor 112 provided on the bypass diode circuit board 11. However, in the bypass diode circuit board 11 of the present disclosure, the mounting portion of the bypass diode 12 may be the second electrode portion 112b.

[0034] In the bypass diode device 1, as shown in FIG. 1, the bypass diode 12 may be disposed so as to face the earth surface side relative to the ceramic substrate 111.

[0035] Fig. 2 shows an example of a solar cell module 2. The solar cell module 2 shown in Fig. 2 includes a solar cell panel 20 and a bypass diode device 1. The solar cell panel 20 has a configuration in which a first film 21, a first resin layer 22, a cell group 23, a second resin layer 24, and a second film 25 are laminated in this order.

[0036] The cell group 23 includes a plurality of series cell groups 231. Note that only one series cell group 231 is shown in FIG. 2. The series cell group 231 includes a plurality of cells 231a electrically connected in series. The series cell group 231 may include a portion of the cell group 23 where the cells are connected in parallel.

[0037] In the solar cell module 2 shown in Figure 2, the first film 21 side is the surface that receives sunlight. The second film 25 side is the side that faces the ground surface. The second film 25 side is also the side that is closer to the ground surface. The first film 21 and the second film 25 are made of, for example, EVA (ethylene vinyl acetate).

[0038] 2 , when the bypass diode device 1 is incorporated into the solar cell module 2, the bypass diode device 1 may be arranged so that the bypass diodes 12 face downward. In other words, for a solar cell module 2 installed on the ground, the bypass diode device 1 may be positioned so that the bypass diodes 12 face opposite the position of the sun, with the ceramic substrate 111 in the middle when considering a direction perpendicular to the ground.

[0039] If the bypass diode 12 is located on the opposite side to the sun (the position receiving sunlight), the bypass diode device 1 is arranged so that the ceramic substrate 111 acts as a shielding plate and is not exposed to sunlight.

[0040] The ceramic substrate 111 blocks sunlight, thereby reducing the temperature rise of the bypass diode 12. Since the time, frequency, and probability of the bypass diode 12 being exposed to sunlight are reduced, deterioration of the bypass diode 12 due to the surrounding environment, such as sunlight or condensation, is suppressed.

[0041] 2 includes a solar cell panel 20 and a bypass diode device 1. In this case, the bypass diode device 1 is disposed on the second resin layer 24.

[0042] The bypass diode device 1 is disposed on the same plane as the cell group 23 on the second resin layer 24. The bypass diode device 1 is sandwiched between the first resin layer 22 and the second resin layer 24 on the same plane as the cell group 23.

[0043] The bypass diode device 1 is preferably arranged around the cell group 23 within the solar cell module 2. When the bypass diode device 1 is arranged around the cell group 23 within the solar cell module 2, the cell group 23 can be arranged in a concentrated manner within the plane, making it possible to obtain a highly efficient solar cell module 2.

[0044] In terms of power generation efficiency of the solar cell module 2, if the bypass diode device 1 is positioned, for example, inside the cell 231a located at the end of the plane of the cell group 23, an area will be created within the cell group 23 where no electromotive force is generated.

[0045] When the bypass diode device 1 is configured to be disposed around the cell group 23 in the solar cell module 2 , heat generated in the bypass diode device 1 is easily dissipated from the side surface of the bypass diode circuit board 11 .

[0046] As long as at least one of the first resin layer 22 and the second resin layer 24 thinly covers the bypass diode device 1, the side surfaces of the bypass diode circuit board 11 may be close to the periphery to such an extent that they are exposed on the side surfaces of the solar cell module 2, as shown in Fig. 2. In this case, the first resin layer 22 and the second resin layer 24 may be in contact with each other and face each other from above and below on the outer side surfaces of the bypass diode device 1 on the periphery of the solar cell module 2. The reason why the side surfaces of the bypass diode circuit board 11 can be exposed from the solar cell module 2 is because the bypass diode circuit board 11 is formed from a ceramic substrate that has high insulation properties, mechanical strength, moisture resistance, weather resistance, and chemical resistance.

[0047] For example, if the bypass diode device 1 is disposed inside the cell 231a located at the end of the plane of the cell group 23, the conductors for electrically connecting the cells within the cell group 23 or the serial cell groups 231 will become longer in some portions, resulting in a decrease in electromotive force, a decrease in generated power, and a decrease in power generation efficiency per unit area.

[0048] The thickness of the bypass diode device 1 is preferably equal to or less than the thickness of the cell 231a or the cell group 23. In this case, the thickness of the electrode portions (third electrode portion 112d and fourth electrode portion 112e) provided on the back surface of the bypass diode circuit board 11 may be thicker than the electrode portions (first electrode portion 112a and second electrode portion 112b) on the bypass diode 12 side. When the thickness relationship of the electrode portions is as described above, it is possible to improve the bond with the conductor arranged on the outside of the bypass diode circuit board 11 and also improve the mechanical strength of the electrode portions.

[0049] The area of ​​the bypass diode device 1 when viewed in plan should preferably be smaller than the area of ​​one cell 231a when viewed in plan.

[0050] For example, if a conventional junction box is provided on the solar cell module 2, the junction box will protrude significantly from the back surface of the solar cell module 2. However, if the bypass diode device 1 of the present disclosure is used, the bypass diode device 1 will fit within the thickness range of the cell group 23, and therefore the flatness of both surfaces of the solar cell module 2 can be maintained.

[0051] If the solar cell module 2 has a so-called flat plate structure, it is possible to stack multiple solar cell modules 2 together without any gaps in the stacking direction. If the solar cell module 2 has a flat plate structure, it is also possible to stack the cell groups 23 and solar cell modules 2 with some bending. Since the bulk (volume) required for transporting multiple solar cell modules 2 can be reduced, transportation efficiency is improved.

[0052] The area of ​​the first electrode portion 112a in a plan view is preferably larger than the area of ​​the adhesive surface of the bypass diode 12. This reduces heat generated in the bypass diode circuit board 11 due to conductivity. Also, it reduces the resistance of the current flowing into or out of the bypass diode 12 in the bypass diode circuit board 11. It also reduces heat generated in the bypass diode 12 due to the connection of the bypass diode circuit board 11 with the conductor 112.

[0053] Fig. 3 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In Fig. 3, for convenience, in order to show the positional relationship with the bypass diode 12, the bypass diode 12 is arranged in the same manner as in Fig. 1.

[0054] As shown in FIG. 3 , the ceramic substrate 111 may have a space 115 therein whose area in a plan view corresponds to the area of ​​the conductor 112 in a plan view. The area of ​​the space 115 in a plan view needs to be at least equal to the area of ​​the conductor 112 in a plan view. In this case, the thermal conductivity of the ceramic substrate 111 can be reduced. In particular, when the surface opposite to the surface on which the conductor 112 is provided is the light-receiving side of the solar cell module 2, the diffusion of heat from the light-receiving side to the surface on which the conductor 112 is provided can be suppressed within the ceramic substrate 111. Furthermore, since the temperature rise of the bypass diode 12 can be suppressed, the bypass diode 12 can be operated stably and its lifespan can be extended.

[0055] Fig. 4 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. Fig. 5 is a plan view of the bypass diode circuit board 11 shown in Fig. 4. Fig. 6 is a diagram showing a configuration in which the bypass diode circuit board 11 shown in Fig. 4 has third and fourth electrode portions on the back surface thereof.

[0056] 4, the first electrode member 13 is bonded to the upper surface of the bypass diode 12. Although not shown, the bypass diode 12 has a first terminal electrode on one surface thereof and a second terminal electrode on the other surface thereof.

[0057] The first electrode portion 112a and the second electrode portion 112b constituting the conductor 112 may be arranged apart from each other so as to be insulated from each other on the ceramic substrate 111. One of the first electrode portion 112a and the second electrode portion 112b serves as a mounting portion for the bypass diode 12. The other of the first electrode portion 112a and the second electrode portion 112b, which is not the mounting portion for the bypass diode 12, serves as an electrode portion to which an external circuit for flowing current outside the bypass diode circuit board 11 is electrically connected.

[0058] The ceramic substrate 111 may have a through conductor portion 112c penetrating through in the thickness direction. The through conductor portion 112c has a plurality of through conductors 112c5. The plurality of through conductors 112c5 are electrically connected to the first electrode portion 112a and the second electrode portion 112b.

[0059] In this case, the bypass diode circuit board 11 also has a configuration in which two electrode portions are arranged on the main surface of the ceramic substrate 111, which allows the circuit including the bypass diode 12 to be made small and thin. Furthermore, since the ceramic substrate 111 has the through conductor portion 112c that penetrates in the thickness direction, heat generated when the bypass diode 12 itself generates heat can be easily transferred to the opposite side of the ceramic substrate 111 from the portion where the bypass diode 12 is mounted.

[0060] 4, the bypass diode circuit board 11 may further include a third electrode portion 112d and a fourth electrode portion 112e. The third electrode portion 112d is provided at a position facing the first electrode portion 112a across the ceramic substrate 111. The fourth electrode portion 112e is provided at a position facing the second electrode portion 112b across the ceramic substrate 111.

[0061] The through conductor portion 112c has a first through conductor portion 112c1 and a second through conductor portion 112c2. The first electrode portion 112a and the third electrode portion 112d are electrically connected via the first through conductor portion 112c1. The second electrode portion 112b and the fourth electrode portion 112e are electrically connected via the second through conductor portion 112c2. The first through conductor portion 112c1 and the second through conductor portion 112c2 may each be formed by a plurality of through conductors 112c5.

[0062] For example, when the bypass diode 12 is disposed on the second electrode portion 112b of the ceramic substrate 111 and the first terminal electrode of the bypass diode 12 is electrically connected to the second electrode portion 112b, the second terminal electrode of the bypass diode 12 is electrically connected to the first electrode portion 112a via the bonding wire 16.

[0063] The area of ​​the third electrode portion 112d in a plan view should be larger than the area of ​​the region of the first penetrating conductor portion 112c1 in a plan view. The area of ​​the fourth electrode portion 112e in a plan view should be larger than the area of ​​the region of the second penetrating conductor portion 112c2 in a plan view. The area of ​​the third electrode portion 112d in a plan view may be larger than the area of ​​the first electrode portion 112a in a plan view. The area of ​​the fourth electrode portion 112e in a plan view may be larger than the area of ​​the second electrode portion 112b in a plan view. In this case, heat is likely to dissipate from the back surface side of the ceramic substrate 111 opposite the mounting portion of the bypass diode 12. The electrode structures may be arranged symmetrically.

[0064] Furthermore, in order to more effectively dissipate heat from the bypass diode 12 when the bypass diode device 1 is viewed from above, it is preferable that the area obtained by connecting the outermost periphery of the second through conductor portion 112c2 provided on the ceramic substrate 111 is larger than the area of ​​the bypass diode 12. In other words, it is preferable that each through conductor 112c5 constituting the second through conductor portion 112c2 is arranged in a state where it is wider than the area of ​​the bypass diode 12 in contact with the second electrode portion 112b.

[0065] The color tone of the ceramic substrate 111 is either black or white. If the color tone of the ceramic substrate 111 is black, it will be the same color as the solar cell, so the design will not be impaired. If the color tone of the ceramic substrate 111 is white, it will easily reflect sunlight, so the element will not easily become hot.

[0066] Fig. 7 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In Fig. 7, for convenience, in order to show the arrangement of the bypass diode 12 within the bank portion 111b, the bypass diode 12 is arranged in the mounting portion, and the lid 116 is also arranged. The configuration shown in Fig. 7 is also the bypass diode device 1.

[0067] The ceramic substrate 111 may have a flat body 111a on which the conductor 112 and the bypass diode 12 are mounted, and a bank 111b (wall member). The bank 111b is disposed on the periphery of the body 111a of the ceramic substrate 111 so as to circumferentially surround the mounting portion of the conductor 112 and the bypass diode 12.

[0068] If the bypass diode circuit board 11 is made to have a cavity structure with the bank portion 111b and is made to be a type in which the lid 116 can be placed on the bank portion 111b, it becomes unnecessary to resin-seal the bypass diodes 12 and bonding wires 16 arranged on the ceramic substrate 111, and therefore it is more likely that the board can be made lower in height than when resin-sealed.

[0069] In this case, the mounting area of ​​the bypass diode 12 inside the bank portion 111b and the lid 116 is filled with gas such as air. Since gas has lower thermal conductivity than resin sealing, heat generated from the bypass diode 12 is more likely to be transferred to the ceramic substrate 111 and the through conductor 112c. In the solar cell module 2, if the lid 116 is disposed in contact with the solar cell panel 20, heat from the bypass diode 12 is more likely to dissipate into the space on the back side of the solar cell panel 20.

[0070] When the bypass diode circuit board 11 is a structure having a bank portion 111b, a lid 116 may be placed on the upper surface of the bank portion 111b. The material of the lid 116 may be a ceramic material of the same quality as the ceramic substrate 111, as long as it is a dense body that can enhance airtightness, but it may also be a metal material. The metal material should preferably have a thermal expansion coefficient close to that of the ceramic substrate 111. For example, Kovar (Fe-Ni-Co) can be used. The thermal expansion coefficient of Kovar is 4.5 to 5×10 －６ / ℃.

[0071] In the case of the bypass diode circuit board 11 having the bank portion 111b shown in FIG. 7 , the electrode portions described below may also have the same configuration as the bypass diode circuit board 11 shown in FIG. 4 . That is, in the bypass diode circuit board 11 having the bank portion 111b shown in FIG. 7 , the area of ​​the third electrode portion 112d in a plan view should be larger than the area of ​​the first penetrating conductor portion 112c1 in a plan view. The area of ​​the fourth electrode portion 112e in a plan view should be larger than the area of ​​the second penetrating conductor portion 112c2 in a plan view. The area of ​​the third electrode portion 112d in a plan view may be larger than the area of ​​the first electrode portion 112a in a plan view. The area of ​​the fourth electrode portion 112e in a plan view may be larger than the area of ​​the second electrode portion 112b in a plan view. In this case, if the area of ​​the electrode portions (third electrode portion 112d, fourth electrode portion 112e) of the bypass diode circuit board 11 that are exposed to the outside are larger than the area of ​​the electrode portions (first electrode portion 112a, second electrode portion 112b) that are arranged within the bank portion 111b, the area available for heat dissipation to the outside increases, making it easier for heat to dissipate from the back surface side of the ceramic substrate 111 opposite the mounting portion of the bypass diode 12. In this case as well, the electrode structures may be arranged symmetrically.

[0072] 7, in order to further dissipate the heat of the bypass diode 12 when the bypass diode device 1 or the circuit board 11 for bypass diodes is viewed in plan, it is preferable that the area obtained by connecting the outermost periphery of the second penetrating conductor portion 112c2 provided on the ceramic substrate 111 (111a) is larger than the area of ​​the bypass diode 12. In other words, it is preferable that each of the penetrating conductors 112c5 constituting the second penetrating conductor portion 112c2 is arranged in a state where it is wider than the area of ​​the bypass diode 12 in contact with the second electrode portion 112b.

[0073] 4, in the case of the bypass diode device 1 shown in Fig. 7, the thicknesses of the electrodes (the third electrode portion 112d and the fourth electrode portion 112e) provided on the back surface of the bypass diode circuit board 11 may be thicker than the electrode portions (the first electrode portion 112a and the second electrode portion 112b) on the bypass diode 12 side. When the thickness relationship of the electrode portions is as described above, it is possible to improve the bond with the conductor arranged on the outside of the bypass diode circuit board 11 and also to improve the mechanical strength of the electrode portions.

[0074] When the thickness of the electrode portion (third electrode portion 112d) provided on the back surface of the bypass diode circuit board 11 is increased, it may be necessary to conversely reduce the thickness of the electrode portions (first electrode portion 112a and second electrode portion 112b) on the bypass diode 12 side. In such a case, the volume of the space 115 within the bank portion 111b on the bypass diode circuit board 11 on which the bypass diode 12 is mounted can be increased. This makes it possible to further suppress the diffusion of heat from the light-receiving side to the surface on which the conductor 112 is provided within the ceramic substrate 111, leading to further suppression of the temperature rise of the bypass diode 12.

[0075] Fig. 8 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In Fig. 8, a part of the mounting portion located inside the bank portion 111b has a stepped structure. For convenience, Fig. 8 also shows a configuration in which the bypass diode 12 is disposed on the mounting portion. The configuration shown in Fig. 8 is also a bypass diode device 1.

[0076] The bank portion 111b has a stepped structure with one step portion 111c. Specifically, the bank portion 111b has the step portion 111c between the mounting surface of the main body portion 111a of the ceramic substrate 111 and the upper surface of the bank portion 111b. A conductive film (fifth electrode portion, here, first electrode portion 112a) is located on the upper surface of the step portion 111c.

[0077] Since the connection position of the bonding wire 16 on the bypass diode circuit board 11 side is close to the height of the bypass diode 12, the length of the bonding wire 16 can be shortened, thereby reducing the resistance of the bonding wire 16.

[0078] 9 and 10 are cross-sectional views showing other embodiments of the bypass diode circuit board 11. As shown in Fig. 9 and 10, the conductor 112 may penetrate the ceramic substrate 111. When the conductor 112 penetrates the ceramic substrate 111 in the thickness direction, heat from the bypass diode 12 (not shown here) mounted on the mounting portion on the conductor 112 can be released directly to the back side of the ceramic substrate 111 via the penetrating conductor 112.

[0079] The area of ​​the mounting portion of the conductor 112, the area of ​​the portion penetrating the ceramic substrate 111 in the thickness direction as viewed in a plan view, and the area exposed on the back surface of the ceramic substrate 111 may be approximately the same ( FIG. 9 ). The cross-sectional shape of the conductor 112 may be trapezoidal or inverted trapezoidal from the mounting portion side to the back surface of the ceramic substrate 111 ( FIG. 10 ). In this case, the conductor 112 is less likely to come off the ceramic substrate 111. When the mounting portion is on the solar cell panel 20 side, the cross-sectional shape of the conductor 112 is preferably inverted trapezoidal. When the mounting portion is on the ground side opposite the solar cell panel 20, the cross-sectional shape of the conductor 112 is preferably trapezoidal. When the cross-sectional shape of the conductor 112 is trapezoidal, the conductor 112 is preferably arranged so that the upper surface (the side with the smaller area) of the trapezoid faces the ground.

[0080] Fig. 11 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. As shown in Fig. 11, the bypass diode circuit board 11 may have a conductor 112 with a convex cross-sectional shape. In this case, the convex conductor 112 may penetrate the ceramic substrate 111. Because the conductor 112 is convex, the through-hole 111d of the ceramic substrate 111 is shaped to fit the convex conductor 112.

[0081] The convex conductors 112 are arranged so as to fit into the concave through-holes 111d at the steps of the ceramic substrate 111. In the case of the bypass diode circuit board 11 shown in FIG. 11 , two convex conductors 112 are arranged in two concave through-holes 111d with steps provided in the ceramic substrate 111, respectively.

[0082] One of the convex conductors 112 serves as a mounting portion for mounting the bypass diode 12. The other convex conductor 112 serves as a connecting portion for connecting the bonding wire 16 extending from the bypass diode 12, as shown in Fig. 11. The other convex conductor 112 serves as a terminal or electrode for connecting the bonding wire 16 extending from the bypass diode 12, as shown in Fig. 11.

[0083] The bypass diode circuit board 11 shown in FIG. 11 has a shape that widens on the side opposite the installation surface of the bypass diode 12, thereby improving heat dissipation toward the back surface of the ceramic substrate 111. It also reduces the electrical resistance of the conductors 112. In this case, it is preferable that the two conductors 112 have the same shape and volume, so that stresses such as thermal stresses generated within the surface of the ceramic substrate 111 can be made symmetrical when viewing FIG. 11 from the front to the back of the page. Note that "same shape and volume" also includes cases where the shapes or dimensions of the respective sides, corners, and edges may vary slightly, as long as the basic shape is a convex shape when viewed from a distance.

[0084] 1, the bypass diode device 1 includes a bypass diode 12 on any of the above-described bypass diode circuit boards 11. Because the bypass diode device 1 uses a thin bypass diode circuit board 11, it is possible to obtain a bypass diode device 1 that is thinner or smaller than a conventional junction box type.

[0085] 2, the solar cell module 2 includes a solar cell panel 20 and a bypass diode device 1. Because the bypass diode device 1 uses a thin bypass diode circuit board 11, the solar cell module 2 can be finished as a thin solar cell module 2 that does not protrude from the solar cell panel 20, unlike conventional junction box types.

[0086] As described above, the solar cell panel 20, the first film 21, the first resin layer 22 (transparent resin layer), the cell group 23 (solar cell), the second resin layer 24 (white resin layer), and the second film 25 are laminated in this order. The bypass diode device 1 is contained within the thickness of the solar cell panel 20. This makes the solar cell module 2 appear as a plate-like body of uniform thickness.

[0087] The solar cell module 2 of the present disclosure can reduce transportation costs and improve installation ease in automotive applications, etc. Fig. 12 is a schematic diagram of an automobile 50 equipped with the solar cell module 2. The solar cell module 2 of the present disclosure allows the roof of the automobile 50 to have a flatter structure.

[0088] (Example) The relationship between the fabricated samples 1 to 6 and the drawings is as follows: Sample 1 corresponds to the bypass diode circuit board shown in Fig. 1, sample 2 in Fig. 4, sample 3 in Fig. 7, sample 4 in Fig. 8, sample 5 in Fig. 9, and sample 6 in Fig. 10.

[0089] Green sheets containing various ceramic powders of alumina, aluminum nitride, and glass ceramics were prepared.

[0090] Next, conductor patterns were formed on these green sheets with a predetermined area. If necessary, through holes were formed in the green sheets. This resulted in the production of bypass diode circuit boards having through conductors (including multiple through conductors) or conductors that penetrated the green sheets. The firing conditions were the same as those normally used when using the above-mentioned ceramic powders.

[0091] When the bypass diode circuit board had a bank portion, it was fabricated by laminating a frame-shaped body cut out from a green sheet onto a plate-shaped green sheet. The bypass diodes were mounted on the conductors of each fabricated bypass diode circuit board using a resin adhesive (soldering was also acceptable).

[0092] The bypass diodes used were rectangular parallelepiped type with terminal electrodes formed to cover almost the entire surface of both main surfaces. The bypass diode conductors (electrodes) were connected using a metal film and a resin adhesive (solder was also acceptable).

[0093] Samples 1 to 6 were prepared from the green sheets using alumina and glass ceramics, and samples 4 to 6 were prepared from the green sheets using aluminum nitride.

[0094] Bypass diodes were mounted on Samples 1, 2, 3 and 4 (Kovar was used for the lids) to fabricate bypass diode devices, which were then mounted on solar cell panels to fabricate solar cell modules.

[0095] All solar cell modules incorporating bypass diode devices were of the same thickness and did not have the protrusions caused by conventional junction boxes. It was found that the design meant that even when mounted on the roof of a car, no protruding parts would be visible inside the car.

[0096] As explained above, the bypass diode device 1 of the present disclosure can be said to have the functionality of a junction box built into a low-profile package. In other words, the bypass diode circuit board 11 of the present disclosure is a wiring board that can have the functionality of a junction box built into a low-profile package. Here, low profile can also be rephrased as thin.

[0097] The bypass diode circuit board 11 of the present disclosure can also incorporate IC functions by placing the diode adjacent to the low-profile package, thereby improving functionality.

[0098] Here, examples of the function include a function to control charging or discharging of a storage battery when the solar cell module 2 is equipped with an adjacent storage battery. A controller having such a function to control charging or discharging of a storage battery is called a charge controller. A charge controller may not only have the function of charging or discharging a storage battery, but may also have a combined charging and discharging function. In addition to the charge or discharge control or management function, the charge controller may also have an overcharge prevention function (such as the ability to set various voltages arbitrarily) including automatic output stop for battery protection (charging protection), and a discharge prevention function to prevent backflow of current toward the solar cell panel 20.

[0099] Another function is to convert the power (DC) generated or stored by solar power generation into power (AC) that can be used at home. A DC / AC inverter is suitable for this purpose.

[0100] Furthermore, when the solar cell module 2 is equipped with an LCD monitor, the function of the LCD monitor can include displaying or recording the amount of power supplied by the inverter, the amount of power generated by the solar panel, the battery voltage, etc. In this case, the charging or operating status of the solar cell panel 20 can be confirmed or stored on the separately installed LCD monitor.

[0101] The amount of power generated by the solar cell panel 20 is usually determined by voltage (V) x current (I), but by using a charge controller, it is possible to generate power only when a certain combination of solar cell voltage and current is achieved. In other words, the solar cell module 2 described above can be equipped with a function that controls the output voltage and current and selects the combination that always produces the maximum amount of power. This results in high conversion efficiency and stable power generation even on cloudy days when the amount of solar radiation varies. Such a solar cell module 2 detects the balance between the amount of power generated by the solar cell panel 20 and the capacity of the storage battery, and works to achieve optimal performance (current value) at that time.

[0102] As an additional function, it is desirable that the self-power consumption of the semiconductor element itself can also be controlled. Furthermore, according to the disclosed solar cell module 2, as described above, the bypass diode device 1 can be embedded in the solar cell panel 20 together with the bypass diode circuit board 11.

[0103] The solar cell module 2 of the present disclosure can be easily installed on mobility vehicles. Examples of mobility vehicles include automobiles, motorcycles, bicycles, handcarts, tricycles (for small children), mobility vehicles for the elderly (maximum speed of approximately 5 km / h), wheelchairs for the disabled, wheelchairs for sports, carts (electric vehicles and engine vehicles) at amusement parks, wheelchairs at hospitals, airports, train stations, etc., trains, and airplanes. For example, the solar cell module 2 is suitable for installation on objects with curved surfaces, such as the roof of a car. It is also suitable for use on motorcycles or bicycles, where it is difficult to install the solar cell panel 20 in a rectangular shape.

[0104] The bypass diode device 1 is also suitable for cases where the solar cell panel 20 itself has a shape with a curved surface. This is because the bypass diode device 1 is incorporated into the thickness of the solar cell panel 20, and therefore there is no unnecessary protrusion when the surface of the solar cell panel 20 is used as the reference plane. In other words, even if the solar cell module 2 of the present disclosure includes the bypass diode device 1, both surfaces of the solar cell module 2 are entirely parallel. In other words, both surfaces of the solar cell panel 20 are also entirely parallel.

[0105] When multiple solar cell panels 20 or solar cell modules 2 are stacked, their surfaces overlap without any gaps. Compared to solar cell panels 20 or solar cell modules 2 equipped with conventional junction boxes, this configuration reduces the likelihood of unnecessary space being created between the overlapping surfaces. This reduces the bulk (volume) of the solar cell panels 20 or solar cell modules 2 during transportation. For example, when transporting solar cell panels 20 or solar cell modules 2 on a vehicle with limited load capacity, such as a truck, a larger number of solar cell panels 20 or solar cell modules 2 can be transported at one time. Furthermore, when multiple solar cell panels 20 or solar cell modules 2 are stacked without any gaps, there is no need for buffering material to fill such gaps. Furthermore, when multiple solar cell panels 20 or solar cell modules 2 are stacked without any gaps, the stacked solar cell panels 20 or solar cell modules 2 can be handled as a single unit. The integrated solar cell panels 20 or solar cell modules 2 form a structure that mutually complements each other in mechanical strength. In this way, if multiple solar cell panels 20 or solar cell modules 2 are stacked without any gaps, they can have high durability against external loads such as impacts.

[0106] In the case of the solar cell panel 20 or solar cell module 2 of the present disclosure, it is possible to improve the ease of transporting and installing the solar cell panel 20 or solar cell module 2, rather than the solar cell panel 20 or solar cell module 2 itself. In addition, it is possible to reduce the costs associated with such transportation or installation. This also leads to a reduction in the financial burden at the time of initial introduction of the solar cell module 2. For example, this is suitable for a simple solar cell module 2, typified by a stick-on type.

[0107] As described above, if multiple solar cell panels 20 or solar cell modules 2 can be stacked without gaps, it is possible to reduce the workload and costs not only during installation but also when dismantling and transporting the solar cell modules 2 when they are no longer in use and are to be discarded. This also contributes to the reuse of the solar cell panels 20 or solar cell modules 2. This is because, in the case of solar cell panels 20 or solar cell modules 2, the series of tasks such as transportation, installation, and dismantling are almost the same regardless of whether the installation location is small or large, except for the time required, and therefore, in the case of small-scale solar cell modules 2 for home use, for example, this contributes more to the costs borne by individuals.

[0108] The present technology can be configured as follows. (1) A circuit board for a bypass diode, comprising: a ceramic substrate; and a conductor, wherein the conductor is arranged as a single sheet on a main surface of the ceramic substrate, the conductor has a first electrode portion and a second electrode portion, a bypass diode is provided on the first electrode portion and electrically connects the bypass diode, and the second electrode portion is a region of the conductor excluding the first electrode portion. (2) The circuit board for a bypass diode according to (1), wherein an area of ​​the first electrode portion is larger than an area of ​​an adhesive surface of the bypass diode. (3) The circuit board for a bypass diode according to (1) or (2), wherein the ceramic substrate has an internal space having an area equivalent to an area of ​​the conductor. (4) The circuit board for bypass diodes according to (1) or (2), wherein the first electrode portion and the second electrode portion are disposed on the ceramic substrate at a distance from each other so as to be insulated from each other, one of the first electrode portion and the second electrode portion serves as a mounting portion for the bypass diode, the ceramic substrate has a through conductor portion penetrating in a thickness direction, the through conductor portion having a plurality of through conductors, and the plurality of through conductors are electrically connected to the first electrode portion and the second electrode portion. (5) The circuit board for bypass diodes according to any one of (1) to (4), wherein the ceramic substrate has a black or white color tone. (6) The circuit board for bypass diodes according to any one of (1) to (5), wherein the ceramic substrate has a bank portion, and the bank portion is disposed on the peripheral edge of the ceramic substrate so as to circumferentially surround the conductor and the mounting portion for the bypass diode. (7) The circuit board for bypass diodes according to (6), wherein the bank portion has a stepped structure having one step portion, and the step portion has a conductive film. (8) The circuit board for bypass diodes according to any one of (1) to (7), wherein the conductor has a portion that penetrates the ceramic substrate in a thickness direction. (9) A bypass diode device comprising the circuit board for bypass diodes according to any one of (1) to (8), and the bypass diode.(10) A solar cell module comprising: the bypass diode device according to (9); and a solar cell panel. (11) The solar cell module according to (10), wherein the solar cell panel is configured by laminating a first film, a transparent resin layer, a solar cell, a white resin layer, and a second film in this order, and the bypass diode device is contained within the thickness range of the solar cell panel.

[0109] REFERENCE SIGNS LIST 1 bypass diode device 2 solar cell module 11 bypass diode circuit board 12 bypass diode 13 first electrode member 14 second electrode member 20 solar cell panel 21 first film 22 first resin layer 23 cell group 24 second resin layer 25 second film 111 ceramic substrate 111a main body 111b bank portion 112 conductor 112a first electrode portion 112b second electrode portion 112c through conductor portion 112d third electrode portion 112e fourth electrode portion 115 space portion 116 lid 121 bonding material 231 series cell group 231a cell

Claims

1. A circuit board for bypass diodes comprising: a ceramic substrate; and a conductor, the conductor being arranged as a single sheet on a main surface of the ceramic substrate, the conductor having a first electrode portion and a second electrode portion, the first electrode portion having a bypass diode disposed thereon and electrically connecting the bypass diode, and the second electrode portion being an area of ​​the conductor excluding the first electrode portion.

2. The circuit board for bypass diodes according to claim 1, wherein the area of ​​said first electrode portion is larger than the area of ​​the adhesive surface of said bypass diode.

3. The circuit board for bypass diodes according to claim 1 or 2, wherein the ceramic substrate has an internal space having an area equivalent to that of the conductor.

4. A circuit board for a bypass diode as described in claim 1 or 2, wherein the first electrode portion and the second electrode portion are arranged at a distance from each other so as to be insulated from each other on the ceramic substrate, one of the first electrode portion and the second electrode portion serves as a mounting portion for the bypass diode, the ceramic substrate has a through conductor portion penetrating in a thickness direction, the through conductor portion has a plurality of through conductors, and the plurality of through conductors are electrically connected to the first electrode portion and the second electrode portion.

5. The circuit board for bypass diodes according to any one of claims 1 to 4, wherein the color tone of the ceramic substrate is either black or white.

6. The circuit board for bypass diodes according to any one of claims 1 to 5, wherein the ceramic substrate has a bank portion, and the bank portion is disposed on the peripheral edge of the ceramic substrate so as to circumferentially surround the mounting portion for the conductor and the bypass diode.

7. The circuit board for bypass diodes according to claim 6, wherein the bank portion has a stepped structure having one step portion, and the step portion has a conductor film.

8. The circuit board for bypass diodes according to any one of claims 1 to 7, wherein the conductor has a portion penetrating the ceramic substrate in the thickness direction.

9. A bypass diode device comprising the bypass diode on the circuit board for bypass diodes according to any one of claims 1 to 8.

10. A solar cell module comprising: the bypass diode device according to claim 9; and a solar cell panel.

11. The solar cell module according to claim 10, wherein the solar cell panel is configured by stacking a first film, a transparent resin layer, a solar cell, a white resin layer, and a second film in that order, and the bypass diode device is contained within the range of the thickness of the solar cell panel.

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