Circuit board for bypass diode, bypass diode device, and solar cell module
Patent Information
- Application Number
- PCT/JP2026/012997
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2026-03-27
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026012997_01102026_PF_FP_ABST
Abstract
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, photovoltaic power generation has been increasingly popularized as renewable energy. Current solar cell modules are usually provided with a junction box on the back surface thereof.
[0003] The junction box has a bypass diode therein. The bypass diode functions to bypass current and protect solar cells when a failure such as shadow shading occurs on the solar cell module (see, for example, Patent Document 1).
[0004] Japanese Patent Laying-Open No. 2015-185784
[0005] A circuit board for a bypass diode according to one aspect of the present disclosure includes a ceramic substrate and a conductor. The conductor is arranged in an isolated island shape as a single piece in a central region of the 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 the bypass diode is mounted and for electrically connecting the bypass diode. The second electrode portion is a region of the conductor excluding the first electrode portion.
[0006] Figure 1 is a cross-sectional view of a bypass diode device as an example of an embodiment. Figure 2 is a plan view of a ceramic substrate and conductor as an example of an embodiment. Figure 3 is an exploded perspective view of a ceramic substrate and conductor as an example of an embodiment. Figure 4 is a cross-sectional view of a solar cell module as an example of an embodiment. Figure 5 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 6 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 7 is a plan view of the ceramic substrate and conductor assembly shown in Figure 6. Figure 8 is an exploded perspective view of the ceramic substrate and conductor assembly shown in Figure 6. Figure 9 is a plan view of the circuit board for a bypass diode shown in Figure 6. Figure 10 is a diagram showing a configuration in which the circuit board for a bypass diode shown in Figure 6 has a third electrode portion and a fourth electrode portion on the back surface. Figure 11 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 12 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 13 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 14 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 15 is a cross-sectional view showing another embodiment of a circuit board for a bypass diode. Figure 16 is a schematic diagram of a car equipped with a solar cell module.
[0007] Hereinafter, a circuit board for a bypass diode according to an embodiment, a bypass diode device using the same, and a solar cell module will be described with reference to the drawings. Note that an embodiment of this disclosure is not limited to the specific embodiment described below. An embodiment of this disclosure includes a variety of embodiments, as long as they are in line with the spirit or scope of the overall concept of the invention as defined by the appended claims.
[0008] The conventional technology described above has room for improvement in terms of making circuits with junction boxes containing bypass diodes smaller or thinner.
[0009] Figure 1 is a cross-sectional view of a bypass diode device 1 shown as an example of an embodiment. Figure 2 is a plan view of a ceramic substrate 111 and a conductor 112 shown as an example of an embodiment. Figure 3 is an exploded perspective view of the ceramic substrate 111 and conductor 112 shown as an example of an embodiment. Figure 4 is a cross-sectional view of a solar cell module 2 shown as an example of an embodiment.
[0010] As shown in Figure 1, the bypass diode device 1, shown as an example of an embodiment, includes a bypass diode circuit board 11 and a bypass diode 12.
[0011] 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 arranged in an isolated island-like manner in the central region 111ac of the main surface 111a of the ceramic substrate 111. The conductor 112 has a first electrode portion 112a and a second electrode portion 112b.
[0012] According to the bypass diode circuit board 11, since the conductor 112 is simply placed on the main surface 111a of the ceramic substrate 111, the circuit equipped with the bypass diode 12 can be made smaller or thinner.
[0013] As shown in Figure 2, if we liken the main surface 111a of the ceramic substrate 111 to the sea, the conductor 112 is like an isolated island floating in the open ocean. The conductor 112 exists alone on the ceramic substrate 111. As the term "open ocean" suggests, there are no other conductors on the surface of the ceramic substrate 111 other than the single conductor 112. The conductor referred to here may function as part of a circuit. For example, the conductor does not have to include non-electrical elements such as alignment marks formed by metallization.
[0014] On the main surface 111a of the ceramic substrate 111, the surface of the ceramic substrate 111 is exposed around the conductor 112. The central region 111ac of the main surface 111a of the ceramic substrate 111 is the region that includes the center point C1 of the ceramic substrate 111. As shown in Figure 3, the center point C1 of the ceramic substrate 111 is, for example, the position where two diagonals intersect when two diagonals are drawn connecting opposite corners of the four corners of the quadrilateral, such as a square or rectangle when viewed from above.
[0015] When the center point C2 of the conductor 112 is determined using the same method as described above for the ceramic substrate 111, it is preferable that the center point C2 coincides with the center point C1 of the main surface 111a of the ceramic substrate 111. However, the center point C2 of the conductor 112 does not necessarily coincide with the center point C1 of the main surface 111a of the ceramic substrate 111; it may be offset. For example, the center point C1 of the ceramic substrate 111 may be within the area of the conductor 112.
[0016] The central region 111ac on the main surface 111a of the ceramic substrate 111 is the area that includes the center point C1 and has a predetermined area. As shown in Figure 2, the ratio of the area of the central region 111ac can be set to 10% to 70% when the area of the ceramic substrate 111 is set to 100% in a plan view from a direction perpendicular to the main surface 111a. The reason why a numerical range for the ratio of the area of the central region 111ac is given as an example is that the area of the conductor 112 formed on this ceramic substrate 111 affects the size of the bypass diode, the electrical characteristics such as conductivity required for the bypass diode circuit board 11, and the mechanical strength of the bypass diode circuit board 11 itself. It is better to allow flexibility in the size, including the thickness of the conductor 112, depending on the application.
[0017] In the case of the bypass diode circuit board 11 of this disclosure, in a plan view taken from a direction perpendicular to the main surface 111a, the area of the conductor 112 is preferably 60% or less of the area of the main surface 111a of the ceramic substrate 111. As an example of the range of the area ratio of the conductor 112, the lower limit is 10% and the upper limit is 60%, when the area of the ceramic substrate 111 is set to 100%. Expressed in other words, when the area ratio of the conductor 112 is set to 1, the area of the conductor 112 is 0.1 or more and 0.6 or less. The area of the conductor 112 on the main surface 111a of the ceramic substrate 111 is preferably smaller than the area where the conductor 112 does not exist. When the area of the conductor 112 is 60% or less of the area of the main surface 111a of the ceramic substrate 111, the total thickness of the area around the conductor 112 on the main surface 111a is thinner by the amount where the conductor 112 does not exist. Furthermore, the small area of the conductor 112 reduces the thermal stress between the conductor 112 and the ceramic substrate 111, thereby reducing the possibility of deformation or delamination of the conductor 112. On the other hand, if the area of the conductor 112 is 10% or more of the area of the main surface 111a of the ceramic substrate 111, the resistance value of the conductor 112 will not become too low.
[0018] Furthermore, if the conductor 112 is located in the central region 111ac of the main surface 111a, then the areas without the conductor 112 on the main surface 111a are arranged symmetrically with respect to the conductor 112 located in the center. As a result, the bypass diode circuit board 11 is prone to bending symmetrically around the conductor 112 located in the central region 111ac of the main surface 111a. Alternatively, it can be said that the areas without the conductor 112 are arranged radially around the conductor 112. As a result, the bypass diode circuit board 11 is also prone to bending radially around the conductor 112 located in the central region 111ac of the main surface 111a. Even when the ceramic substrate 111 deforms, if it has a shape that makes it prone to bending radially around the conductor 112 on the main surface 111a, then even if the ceramic substrate 111 deforms, the stress will be distributed around the conductor 112 located in the central region 111ac (the entire circumference). As a result, the ceramic substrate 111 will have high durability.
[0019] Of the conductor 112, the first electrode portion 112a is the 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.
[0020] The second electrode portion 112b is basically the 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.
[0021] Since the conductor 112 is a single piece 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. That is, the first electrode portion 112a and the second electrode portion 112b are of the same pole and have the same potential.
[0022] On the conductor 112, there may be a region between the first electrode portion 112a and the second electrode portion 112b where the bypass diode 12 is not mounted or where conductive members such as connecting wires are not placed.
[0023] The statement that the conductor 112 is a single piece means that, as shown in Figure 1, it constitutes a single metal film.
[0024] The conductor 112 may have different thicknesses between the first electrode portion 112a and the second electrode portion 112b. The conductor 112 may have portions with different thicknesses at any location on the conductor 112, regardless of whether it is designated as the first electrode portion 112a or the second electrode portion 112b.
[0025] If 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 is possible when it is desirable to make the height of the bypass diode 12 the same as the height of the conductive member, or to reduce the difference in their heights.
[0026] The second electrode portion 112b is a conductor portion for allowing current to flow outside the bypass diode circuit board 11. The second electrode portion 112b is a conductor portion for drawing current from the external circuit to the bypass diode 12. When electrically connected, these are covered with organic resin 15, as shown in Figure 1.
[0027] The material for the conductor 112 should be a metal with high electrical conductivity. Examples of materials for the conductor 112 include one selected from the group consisting of copper, tungsten, molybdenum, aluminum, iron, nickel, cobalt, solder (Sn-Pb), and precious metals. When copper and tungsten are used as the material for the conductor 112, it is preferable that after sintering, they contain at least one of the following: a mixed composition, an intermetallic compound, and an alloy.
[0028] The material of the conductor 112 should have high thermal conductivity. In this case, copper and silver are suitable. As the material of the conductor 112, a material that can be fired together with the ceramic substrate 111 may be selected. Alternatively, the conductor 112 may be formed by firing it onto a pre-sintered ceramic substrate 111. When formed by firing, 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 forming the metal-containing composition on the ceramic substrate 111 using a coating method or printing method, it is preferable to use a so-called paste-like material which is a mixture of metal powder and an organic vehicle.
[0029] The shape of the ceramic substrate 111 can be selected to any shape according to the design of the bypass diode device 1 and the solar cell module 2 on which the bypass diode device 1 is mounted.
[0030] When the ceramic substrate 111 is viewed from above, its basic shape may be rectangular, circular, elliptical, or a polygonal shape other than rectangular.
[0031] When the basic shape of the ceramic substrate 111 is a rectangle, circle, ellipse, or polygon other than a rectangle, the ceramic substrate 111 may have recesses or protrusions on its corners or on the sides between two corners.
[0032] The material used for the ceramic substrate 111 can be any material that primarily contains at least one selected from the group including alumina, mullite, silicon nitride, aluminum nitride, silica, forsterite, and glass ceramics. This is because these materials can result in a ceramic substrate that exhibits high properties in terms of insulation, mechanical strength, moisture resistance, weather resistance, and chemical resistance.
[0033] The basic configuration of the bypass diode device 1 of this disclosure is such that the bypass diode 12 is mounted on the conductor 112.
[0034] The bypass diode 12 is fixed to the bypass diode circuit board 11 via a bonding material 121. The bonding material 121 can be solder or a conductive adhesive, but a conductive adhesive containing metal particles in an organic resin may be selected for its heat resistance.
[0035] In the bypass diode device 1 shown in Figure 1, in addition to the bypass diode 12, a first electrode member 13 is bonded to the surface of the bypass diode 12. The first electrode member 13 is bonded to the surface of the bypass diode 12, for example, via a bonding material 121.
[0036] In the bypass diode device 1 shown in Figure 1, in addition to the bypass diode 12, a second electrode member 14 is joined to the second electrode portion 112b. A bonding material is also used to join the second electrode portion 112b and the second electrode member 14. In this case as well, the bonding material 121 used to join the bypass diode 12 to the bypass diode circuit board 11 may be used, but bonding materials with different melting temperatures may also be used. For example, if a bonding material with a lower melting temperature than the bonding material 121 used to join the bypass diode 12 to the bypass diode circuit board 11 is used, even if the second electrode member 14 is joined to the second electrode portion 112b after the bypass diode 12 has been joined to the bypass diode circuit board 11, the bonding material 121 is less likely to melt, thus maintaining a strong bond between the bypass diode 12 and the bypass diode circuit board 11.
[0037] Furthermore, the portion of the second electrode member 14 that is attached to the second electrode portion 112b (joint portion 14a) is preferably joined in a way that the surfaces of the joint portion 14a and the second electrode portion 112b overlap. When the joint portion 14a of the second electrode member 14 and the second electrode portion 112b are joined surface by surface, the contact area between the joint portion 14a of the second electrode member 14 and the second electrode portion 112b can be increased. As a result, it becomes possible to improve the conductivity from the second electrode portion 112b to the second electrode member 14.
[0038] The area ratio in which the joint portion 14a of the second electrode member 14 contacts the second electrode portion 112b is preferably 40% to 90% when the area of the surface of the second electrode portion 112b facing the second electrode member 14 is taken as 100%. When the area ratio of the second electrode member 14 to the second electrode portion 112b at the joint surface between the second electrode member 14 and the second electrode portion 112b is 40% or more, in addition to being able to increase conductivity, it leads to an improvement in the mechanical strength of the electrode portion due to the joint portion 14a of the second electrode member 14 and the second electrode portion 112b being joined in an overlapping manner. As a result, even when the thickness 111t of the ceramic substrate 111 is thin, it is possible to increase the rigidity of the bypass diode circuit board 11 when viewed as a whole, and a bypass diode device 1 with high durability can be obtained.
[0039] The upper limit of the area ratio in contact between the joint portion 14a of the second electrode member 14 and the second electrode portion 112b is set to 90% because, when the joint portion 14a of the second electrode member 14 and the second electrode portion 112b are superimposed on each other's surfaces, even if both electrodes shift in a direction parallel to the joint surface, the joint portion 14a of the second electrode member 14 will remain within the plane of the second electrode portion 112b. In this way, it becomes possible to firmly join the joint portion 14a of the second electrode member 14 and the second electrode portion 112b both electrically and mechanically.
[0040] The bypass diode device 1 of this disclosure is not limited thereto. The bypass diode device 1 of this disclosure is sufficient if the bypass diode 12 is mounted on the conductor 112.
[0041] The bypass diode 12 is a junction of a P-type semiconductor and an N-type semiconductor. In Figure 1, the bypass diode 12 is shown mounted on the first electrode portion 112a of the conductor 112 provided on the bypass diode circuit board 11, but the bypass diode circuit board 11 of this disclosure may also have the mounting portion of the bypass diode 12 as the second electrode portion 112b.
[0042] In the bypass diode device 1, as shown in FIG. 1, the bypass diode 12 may be arranged at a position closer to the installation surface side than the ceramic substrate 111. Here, the installation surface side may refer to the side opposite to the sunlight-receiving side.
[0043] FIG. 4 shows an example of a solar cell module 2. The solar cell module 2 shown in FIG. 4 includes a solar cell panel 20 and the 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.
[0044] The cell group 23 includes a plurality of series cell groups 231. Note that FIG. 4 shows only one series cell group 231. The series cell group 231 is formed by electrically connecting a plurality of cells 231a in series. The cell group 23 may have a portion where the plurality of series cell groups 231 are connected in parallel.
[0045] In the solar cell module 2 shown in FIG. 4, the first film 21 side serves as a surface that receives sunlight. The second film 25 side is the installation surface side. The second film 25 side is also the side closer to the installation surface. The first film 21 and the second film 25 are made of, for example, EVA (ethylene vinyl acetate).
[0046] As shown in FIG. 4, when the bypass diode device 1 is incorporated into the solar cell module 2, the bypass diode device 1 may be arranged such that the bypass diode 12 faces downward. In other words, when considering the direction perpendicular to the installation surface of the solar cell module 2 installed on an object, the bypass diode 12 may be located on the opposite side to the position of the sun with the ceramic substrate 111 located between the bypass diode 12 and the sun.
[0047] With the structure in which the bypass diode 12 is located on the opposite side to the position of the sun (the position that receives sunlight), the bypass diode 12 is not irradiated with sunlight because the ceramic substrate 111 functions as a shielding plate.
[0048] Since the ceramic substrate 111 blocks sunlight, the temperature rise of the bypass diode 12 can be reduced. As the time, frequency, and probability of the bypass diode 12 being exposed to sunlight are reduced, degradation of the bypass diode 12 due to sunlight or condensation and other environmental factors can be suppressed.
[0049] The solar cell module 2 shown in Figure 4 comprises a solar cell panel 20 and a bypass diode device 1. In this case, the bypass diode device 1 is arranged on a second resin layer 24.
[0050] The bypass diode device 1 is arranged 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.
[0051] 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.
[0052] If the bypass diode device 1 is positioned, for example, inside the cell 231a located at the edge of the cell group 23 in its plane, a region will be created within the cell group 23 in which no electromotive force is generated.
[0053] If the bypass diode device 1 is positioned, for example, inside the cell 231a located at the edge of the cell group 23, then the length of the conductors used to electrically connect cells within the cell group 23, or series cell groups 231, will increase. This will result in a decrease in electromotive force, a decrease in generated power, and a decrease in power generation efficiency per unit area.
[0054] The thickness of the bypass diode device 1 should be the same as or less than the thickness of cell 231a or cell group 23.
[0055] The area of the bypass diode device 1 when viewed from above should be smaller than the area of a single cell 231a when viewed from above.
[0056] 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, by using the bypass diode device 1 of this disclosure, the bypass diode device 1 will be contained within the thickness range of the cell group 23, thereby maintaining the flatness of both sides of the solar cell module 2.
[0057] If the solar cell module 2 is a so-called flat plate type structure, it becomes possible to stack multiple solar cell modules 2 together without gaps in the stacking direction. If the solar cell module 2 is a flat plate type structure, it also becomes possible to stack the cell group 23 and the solar cell modules 2 with some bending. This reduces the bulk (volume) when transporting multiple solar cell modules 2, thus increasing transportation efficiency. Furthermore, if the solar cell module 2 is a so-called flat plate type structure, it becomes easier to install and fix it to flat roofs of houses or vehicles.
[0058] The area of the first electrode portion 112a in a plan view should be larger than the area of the bonding surface of the bypass diode 12. This reduces the heat generated within the bypass diode circuit board 11 due to conductivity. It also reduces the resistance of the current flowing into or out of the bypass diode 12 within the bypass diode circuit board 11. Furthermore, it suppresses the heat generated in the bypass diode 12 due to the connection between the bypass diode circuit board 11 and the conductor 112.
[0059] Figure 5 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In Figure 5, for convenience, a configuration is shown in which the bypass diode 12 is arranged in the same way as in Figure 1, in order to show the positional relationship with the bypass diode 12.
[0060] As shown in Figure 5, the ceramic substrate 111 may have a space 115 inside that overlaps with 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 side opposite to the side 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 side on which the conductor 112 is provided inside the ceramic substrate 111 can be suppressed. Furthermore, since the temperature rise of the bypass diode 12 can be suppressed, the operation stability and lifespan of the bypass diode 12 can be improved. The area of the space 115 in a plan view may be the same as the area of the conductor 112 in a plan view. The area of the space 115 in a plan view may be greater than or equal to the area of the conductor 112 in a plan view. In this case, the outer edge of the conductor 112 may be located inside the outer edge of the space 115 in a plan view. This further reduces the thermal conductivity of the ceramic substrate 111.
[0061] Furthermore, the space 115 may be divided into multiple spaces by partitions (not shown), not limited to the example in Figure 5. In this case, the multiple spaces may be arranged so as to overlap with the conductor 112 in a plan view. In this case, the total area where the multiple spaces and the conductor 112 overlap may be 80% or more of the area of the conductor 112.
[0062] By dividing the ceramic substrate 111 into multiple spaces in this way, its strength can be improved. In other words, the strength of the ceramic substrate 111 can be improved without increasing its total thickness, and its thermal conductivity can be reduced.
[0063] Figure 6 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. Figure 7 is a plan view of the ceramic substrate 111 and the assembled conductor portion shown in Figure 6. Figure 8 is an exploded perspective view of the ceramic substrate 111 and the assembled conductor portion shown in Figure 6. Figure 9 is a plan view of the bypass diode circuit board 11 shown in Figure 6. Figure 10 is a diagram showing a configuration in which the bypass diode circuit board 11 shown in Figure 6 has a third electrode portion 112d and a fourth electrode portion 112e on its back surface. Note that in Figure 8, the sizes of the first electrode portion 112a and the second electrode portion 112b are different from those in Figures 6 and 7.
[0064] In Figure 6, 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 and a second terminal electrode on the other surface.
[0065] In the case of the bypass diode circuit board 11 shown in Figure 6, the conductor 112 is divided into two parts compared to the bypass diode circuit board 11 shown in Figure 1. This conductor 112 has a combined electrode portion 112A in the central region 111ac of the main surface 111a of the ceramic substrate 111. Here, the combined electrode portion 112A refers to a conductor in which two electrode portions, the first electrode portion 112a and the second electrode portion 112b, are in close proximity to each other, as shown in Figure 7. In this case, the combined electrode portion 112A includes the first electrode portion 112a, the second electrode portion 112b, and the insulated region between the first electrode portion 112a and the second electrode portion 112b (referred to as the insulated region 112f).
[0066] The electrode assembly 112A is arranged in an isolated island shape in the central region 111ac of the main surface 111a of the ceramic substrate 111. In other words, the first electrode portion 112a and the second electrode portion 112b are provided in an isolated island shape in the central region 111ac of the main surface 111a of the ceramic substrate 111. The area ratio of this electrode assembly 112A to the main surface 111a of the ceramic substrate 111 is within the same range as in the case of the single-piece conductor 112 described above. The definition of the central region 111ac of the main surface 111a of the ceramic substrate 111 in the bypass diode circuit board 11 shown in Figure 7 is also the same as in the case of the single-piece conductor 112 described above. That is, in this case as well, the central region 111ac of the main surface 111a of the ceramic substrate 111 is the range that includes the center point C1 and has a predetermined area.
[0067] The area ratio of the central region 111ac can be set to be between 10% and 70% when the area of the ceramic substrate 111 is considered to be 100%. The reason why a numerical range for the area ratio of the central region 111ac is given as an example is that the area of the conductor 112 formed on the ceramic substrate 111 affects the size of the bypass diode, the electrical characteristics such as conductivity required for the bypass diode circuit board 11, and the mechanical strength of the bypass diode circuit board 11 itself. It is better to allow flexibility in the size, including the thickness of the conductor, depending on the application.
[0068] In the case of the bypass diode circuit board 11 of this disclosure, the area of the electrode assembly portion 112A, which is the conductor 112, is preferably 60% or less of the area of the main surface 111a of the ceramic substrate 111. As an example of the range of the area ratio of the electrode assembly portion 112A, in this case as well, the lower limit can be 10% and the upper limit can be 60% when the area of the ceramic substrate 111 is set to 100%. Expressed in other words, the area ratio of the electrode assembly portion 112A is such that when the area of the main surface 111a of the ceramic substrate 111 is set to 1, the area of the electrode assembly portion 112A is 0.1 or more and 0.6 or less. The area of the electrode assembly portion 112A on the main surface 111a of the ceramic substrate 111 is preferably smaller than the area where the electrode assembly portion 112A does not exist. If the area of the electrode assembly portion 112A is 60% or less of the area of the main surface 111a of the ceramic substrate 111, then the total thickness of the main surface 111a around the electrode assembly portion 112A is thinner because the conductor 112 is not present.
[0069] Furthermore, if the electrode assembly portion 112A is located in the central region 111ac of the main surface 111a, then the portion of the main surface 111a without the electrode assembly portion 112A will be arranged symmetrically with respect to the electrode assembly portion 112A located in the center. As a result, the bypass diode circuit board 11 is prone to bending symmetrically with respect to the electrode assembly portion 112A located in the central region 111ac of the main surface 111a. Alternatively, the portion without the electrode assembly portion 112A can be said to be arranged radially with respect to the electrode assembly portion 112A. In this case, as shown in Figure 8, the first electrode portion 112a and the second electrode portion 112b constituting the electrode assembly portion 112A may have different areas. As a result, the bypass diode circuit board 11 is also prone to bending radially with respect to the electrode assembly portion 112A located in the central region 111ac of the main surface 111a. Even if the ceramic substrate 111 deforms, if it has a shape that allows it to easily bend radially around the aggregate electrode portion 112A on the main surface 111a, then even if the ceramic substrate 111 deforms, the stress will be distributed around the entire circumference of the aggregate electrode portion 112A located in the central region 111ac. The aggregate electrode portion 112A will also have high durability in the case of the ceramic substrate 111.
[0070] Furthermore, because the circuit board is divided into two parts, a first electrode section 112a and a second electrode section 112b, the size of each electrode section can be reduced, thereby reducing the thermal stress caused by the difference in thermal expansion between the ceramic substrate 111 and the conductor 112. This also allows for stress distribution. As a result, bending or deformation is less likely to occur, and the bypass diode circuit board 11 exhibits superior durability.
[0071] Furthermore, the center point C2A of the electrode assembly 112A and the center point C1 of the ceramic substrate 111 may be offset from each other, just as in the case where the conductor 112 is a single piece. In other words, in this case as well, when the center point C2A of the electrode assembly 112A is determined, it is preferable that the center point C2A coincides with the center point C1 of the main surface 111a of the ceramic substrate 111. However, the center point C2A of the electrode assembly 112A does not necessarily coincide with the center point C1 of the main surface 111a of the ceramic substrate 111, and may be offset. For example, the center point C1 of the ceramic substrate 111 may be within the area of the electrode assembly 112A.
[0072] The first electrode portion 112a and the second electrode portion 112b, which constitute the conductor 112 (in this case, the combined electrode portion 112A), are spaced apart on the ceramic substrate 111 to provide insulation. One of the first electrode portion 112a and the second electrode portion 112b serves as the mounting portion for the bypass diode 12. Figure 6 shows an example where the second electrode portion 112b serves as the mounting portion for the bypass diode 12. Note that the example in Figure 6 is not limited to the first electrode portion 112a, and the second electrode portion 112b that does not serve as the mounting portion for the bypass diode 12 serves as the electrode portion to which an external circuit for allowing current to flow outside the bypass diode circuit board 11 is electrically connected.
[0073] In the example shown in Figure 6, the bypass diode 12 may be positioned on the opposite side of the sun (not shown) with the ceramic substrate 111 in the center. In this case, of the first electrode portion 112a and the second electrode portion 112b, the portion that does not mount the bypass diode 12 may be an electrode portion connected to an external circuit.
[0074] Furthermore, the bypass diode 12 may be located on the same side as the sun (not shown) relative to the ceramic substrate 111. In this case, the third electrode portion 112d and the fourth electrode portion 112e, which will be described later, may become electrode portions connected to an external circuit.
[0075] The ceramic substrate 111 may have through-conductor portions 112c that penetrate 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.
[0076] In this case as well, the bypass diode circuit board 11 has a configuration in which the two electrode portions are arranged on the main surface of the ceramic substrate 111, so that the circuit equipped with the bypass diode 12 can be made small or thin. In addition, since the ceramic substrate 111 has a through-conductor portion 112c that penetrates in the thickness direction, the heat generated when the bypass diode 12 itself generates heat can be easily transferred to the side of the ceramic substrate 111 opposite to the mounting portion of the bypass diode 12.
[0077] As shown in Figure 6, the bypass diode circuit board 11 may further have a third electrode portion 112d and a fourth electrode portion 112e. The third electrode portion 112d is provided in a position facing the first electrode portion 112a via the ceramic substrate 111. The fourth electrode portion 112e is provided in a position facing the second electrode portion 112b via the ceramic substrate 111.
[0078] In other words, the third electrode portion 112d and the fourth electrode portion 112e are positioned on the back side of the ceramic substrate 111. When the ceramic substrate 111 is viewed in cross-section, it is preferable that the positions of the third electrode portion 112d and the fourth electrode portion 112e on the back side of the ceramic substrate 111 are symmetrical. When viewed in plan from a direction perpendicular to the back side of the ceramic substrate 111, it is preferable that the third electrode portion 112d and the fourth electrode portion 112e have the same area. When the ceramic substrate 111 is viewed in cross-section, it is preferable that the third electrode portion 112d and the fourth electrode portion 112e are symmetrical in terms of their positioning and area relationship, with respect to the conductor 112 or the combined electrode portion 112A located in the central region 111ac of the main surface 111a.
[0079] 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.
[0080] The first through-conductor portion 112c1 and the second through-conductor portion 112c2 should be positioned so that they are within the planes of the first electrode portion 112a and the second electrode portion 112b, respectively. This means that even if a collection electrode portion 112A is formed on the main surface 111a of the ceramic substrate 111, there are no conductors around the collection electrode portion 112A. Consequently, even when the ceramic substrate 111 has a through-conductor portion 112c, the bypass diode circuit board 11 is prone to radial bending around the collection electrode portion 112A and the through-conductor portion 112c located in the central region 111ac of the main surface 111a. Even if the ceramic substrate 111 deforms, if it has a shape that allows it to easily bend radially around the electrode assembly portion 112A within the main surface 111a, then even if the ceramic substrate 111 deforms, the stress will be distributed around the entire circumference of the electrode assembly portion 112A and the through-conductor portion 112c located in the central region 111ac. The ceramic substrate 111 can maintain high durability even when the through-conductor portion 112c is added to the electrode assembly portion 112A.
[0081] For example, if the bypass diode 12 is placed on the second electrode portion 112b of the ceramic substrate 111, and the first terminal electrode of the bypass diode 12 and the second electrode portion 112b are electrically connected, the second terminal electrode of the bypass diode 12 is electrically connected to the first electrode portion 112a via the bonding wire 16.
[0082] The area of the third electrode portion 112d in a plan view should be larger than the area of the first through-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 through-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 easily dissipated from the back side of the ceramic substrate 111 opposite to the mounting portion of the bypass diode 12. The electrode structures may be arranged symmetrically.
[0083] The ceramic substrate 111 is either black or white in color. If the ceramic substrate 111 is black, it will be the same color as the solar cell, so the design will not be compromised. If the ceramic substrate 111 is white, it will reflect sunlight easily, so the element will not become hot.
[0084] Figure 11 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In Figure 11, for convenience, a configuration is shown in which the bypass diode 12 is placed on the mounting section and the cover 116 is placed, in order to show the arrangement of the bypass diode 12 within the ridge portion 111b. The configuration shown in Figure 11 is also a bypass diode device 1.
[0085] The ceramic substrate 111 may have a flat main body portion 111e on which mounting portions for the conductor 112 and the bypass diode 12 are provided, and a dam portion 111b (wall member). The dam portion 111b is arranged on the peripheral edge of the main body portion 111e of the ceramic substrate 111 so as to surround the mounting portions for the conductor 112 and the bypass diode 12 in a circumferential manner.
[0086] If the bypass diode circuit board 11 is made into a cavity structure with a ridge portion 111b, and a cover 116 is placed over the ridge portion 111b, it becomes unnecessary to resin-encapsulate the bypass diode 12 and bonding wire 16 placed on the ceramic substrate 111, thus increasing the likelihood of achieving a lower profile than when resin-encapsulated. In other words, if the bypass diode circuit board 11 has a structure with a ridge portion 111b, the cover 116 may be placed on the upper surface of the ridge portion 111b.
[0087] In this case, the bypass diode 12 may be located on the same side as the sun (not shown) relative to the ceramic substrate 111. At this time, the third electrode portion 112d and the fourth electrode portion 112e may become electrode portions connected to an external circuit.
[0088] Furthermore, the bypass diode 12 may be located on the opposite side from the sun (the position that receives sunlight). This arrangement ensures that the bypass diode device 1 is shielded by the ceramic substrate 111, preventing it from being exposed to sunlight.
[0089] Furthermore, in the case shown in Figure 11, the mounting area for the bypass diode 12 inside the dam portion 111b and the cover 116 is filled with a gas such as air. Since gas has lower thermal conductivity than resin sealing, the heat generated from the bypass diode 12 is more easily transferred to the ceramic substrate 111 and the through-conductor portion 112c. In the solar cell module 2, if the cover 116 is positioned in contact with the solar cell panel 20, the heat from the bypass diode 12 is more easily dissipated by the through-conductor portion 112c into the space on the back side of the solar cell panel 20.
[0090] The material of the lid 116 can be any dense material that enhances airtightness; it may be a ceramic material of the same quality as the ceramic substrate 111, or it may be a metal material. For the metal material, one with a thermal expansion coefficient close to that of the ceramic substrate 111 is preferable. For example, Kovar (Fe-Ni-Co) can be used. The thermal expansion coefficient of Kovar is 4.5 to 5 × 10⁻⁶. －６ It is / ℃.
[0091] Figure 12 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In Figure 12, a portion of the mounting area located inside the ridge portion 111b has a stepped structure. For convenience, Figure 12 also shows a configuration in which the bypass diode 12 is placed on the mounting area. The configuration shown in Figure 12 is also a bypass diode device 1.
[0092] The ridge portion 111b has a stepped structure with one step portion 111c. Specifically, the ridge portion 111b has a step portion 111c between the mounting surface of the main body portion 111e of the ceramic substrate 111 and the upper surface of the ridge portion 111b. A conductive film (the fifth electrode portion, in this case the first electrode portion 112a) is located on the upper surface of the step portion 111c.
[0093] Since the connection position of the bonding wire 16 on the bypass diode circuit board 11 is close to the height of the bypass diode 12, the length of the bonding wire 16 can be shortened. This allows the resistance of the bonding wire 16 to be reduced.
[0094] Figures 13 and 14 are cross-sectional views showing other embodiments of the bypass diode circuit board 11. As shown in Figures 13 and 14, the conductor 112 may penetrate the ceramic substrate 111. When the conductor 112 penetrates the ceramic substrate 111 in the thickness direction, the heat from the bypass diode 12 (not shown here) mounted on the mounting portion on the conductor 112 can be directly dissipated to the back side of the ceramic substrate 111 through the penetrating conductor 112.
[0095] The area of the mounting portion of the conductor 112, the area of the portion that penetrates the ceramic substrate 111 in the thickness direction as seen through the plane, and the area exposed on the back surface of the ceramic substrate 111 may be approximately the same (Figure 13). The shape of the longitudinal cross-section of the conductor 112 may be trapezoidal (not shown) or inverted trapezoidal (see Figure 14) from the mounting portion side to the back surface of the ceramic substrate 111. In other words, the width of the conductor 112 may change from the mounting portion side to the back surface of the ceramic substrate 111. In this case, the conductor 112 will be less likely to come off the ceramic substrate 111. When the mounting portion is the solar cell panel 20, it is preferable that the longitudinal cross-section of the conductor 112 be trapezoidal. This increases thermal conductivity as the heat from the bypass diode 12 diffuses laterally through the conductor 112 and conducts to the back surface of the ceramic substrate 111, thereby improving heat dissipation toward the back surface of the ceramic substrate 111.
[0096] Furthermore, when the mounting section is on the opposite side of the installation surface from the solar panel 20, the vertical cross-sectional shape of the conductor 112 is preferably an inverted trapezoid. As shown in Figure 14, when the vertical cross-sectional shape of the conductor 112 is an inverted trapezoid, the conductor 112 is preferably positioned with the top surface of the trapezoid (the side with the smaller area) facing the installation surface.
[0097] Figure 15 is a cross-sectional view showing another embodiment of the bypass diode circuit board 11. In the bypass diode circuit board 11 shown in Figure 14, the cross-sectional shape of the conductor 112 may be convex. In this case, the convex conductor 112 may penetrate the ceramic substrate 111. Because the conductor 112 is convex, the through hole 111d in the ceramic substrate 111 is shaped to accommodate the convex conductor 112.
[0098] The convex conductor 112 is positioned to fit into the concave through-hole 111d in the stepped area of the ceramic substrate 111. In the case of the bypass diode circuit board 11 shown in Figure 15, two convex conductors 112 are positioned in two stepped, concave through-holes 111d provided in the ceramic substrate 111.
[0099] One end of the convex conductor 112 serves as a mounting portion for mounting the bypass diode 12. The other end of the convex conductor 112 serves as a connection portion for connecting the bonding wire 16 extending from the bypass diode 12, as shown in Figure 15. The other end of the convex conductor 112 serves as a terminal or electrode for connecting the bonding wire 16 extending from the bypass diode 12, as shown in Figure 15.
[0100] According to the bypass diode circuit board 11 shown in Figure 15, the side opposite to the mounting surface of the bypass diode 12 widens. Therefore, the heat from the bypass diode 12 is conducted to the back side of the ceramic substrate 111 while diffusing laterally along the conductor 112, thereby increasing thermal conductivity and improving heat dissipation toward the back side of the ceramic substrate 111. It is also possible to lower the electrical resistance of the conductor 112. In this case, it is preferable that the two conductors 112 have the same shape and volume. Stresses such as thermal stress generated within the plane of the ceramic substrate 111 can be made symmetrical when viewing Figure 14 from front to back. Note that "same shape and volume" means that as long as the basic shape is convex when viewed from a distance, it is acceptable for the shape or dimensions of each side, corner, and edge to be slightly different.
[0101] As shown in Figure 1, the bypass diode device 1 is equipped with a bypass diode 12 on one of the bypass diode circuit boards 11 described above. Because the bypass diode device 1 uses a thin bypass diode circuit board 11, a thinner or smaller bypass diode device 1 can be obtained compared to the conventional junction box type.
[0102] As shown in Figure 4, the solar cell module 2 comprises 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 made thin and does not protrude from the solar cell panel 20, unlike conventional junction box type modules.
[0103] 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 stacked in this order. The bypass diode device 1 is housed within the thickness range of the solar cell panel 20. As a result, the solar cell module 2 takes the form of a plate-like body with equal thickness.
[0104] The solar cell module 2 of this disclosure can reduce transportation costs or improve ease of installation in applications such as automobiles. Figure 16 is a schematic diagram of an automobile 50 equipped with the solar cell module 2. The solar cell module 2 of this disclosure allows for a flatter roof structure for the automobile 50.
[0105] The relationship between the fabricated samples 1 to 7 and the drawings is as follows: Sample 1 corresponds to the bypass diode circuit board shown in Figure 1, Sample 2 to Figure 6, Sample 3 to Figure 11, Sample 4 to Figure 12, Sample 5 to Figure 13, Sample 6 to Figure 14, and Sample 7 to Figure 5.
[0106] The area of each sample when viewed from above was 10 mm x 7 mm. The thickness of each sample (ceramic substrate) was 0.5 mm. In the case of a bypass diode circuit board with a ridge on the ceramic substrate, the height of the ridge was 0.5 mm. The thickness of the conductor was 0.1 mm.
[0107] A green sheet containing various ceramic powders, including alumina, aluminum nitride, and glass ceramics, was prepared.
[0108] Next, a conductive pattern was formed on these green sheets over a predetermined area. If necessary, through-holes were also formed in the green sheets. This resulted in the fabrication of a circuit board for a bypass diode with through-conductor sections (having multiple through-conductors) or conductors penetrating the green sheets. The firing conditions were the same as those typically used when using each of the ceramic powders described above.
[0109] In each sample of the bypass diode circuit board, the conductor pattern was formed so that the area ratio of the conductor or electrode cluster was 60%. For the electrode cluster, the area of the electrode where the bypass diode is mounted was approximately twice the area of the electrode where the bypass diode is not mounted. The planar shape of the conductor or electrode cluster in each sample was rectangular, and the conductor pattern was formed to resemble the planar shape of the ceramic substrate.
[0110] Alumina was used as the ceramic powder, and a mixed composition of copper and tungsten was used as the conductive material. Alternatively, aluminum nitride was used as the ceramic powder, and tungsten as the conductive material. Furthermore, glass ceramics were used as the ceramic powder, and copper as the conductive material.
[0111] In the case of a circuit board for bypass diodes that had a ridge section, it was manufactured by laminating frame-shaped sections cut from a green sheet onto a sheet of green sheet. Bypass diodes were mounted on the conductors of each manufactured bypass diode circuit board using a resin adhesive (solder can also be used).
[0112] For the bypass diode, we prepared a type with a rectangular parallelepiped shape, where terminal electrodes were formed to cover almost the entire surface of both main faces. A metal film + resin adhesive (solder could also be used) was used to connect to the conductor (electrode part) of the bypass diode.
[0113] Samples 1-3 were prepared from green sheets using alumina and glass ceramics. Samples 4-7 were prepared from green sheets using aluminum nitride.
[0114] Bypass diodes were mounted on samples 1, 2, 3, 4, and 7 (a cover (Kovar) was used for the bypass diode circuit boards that had a dam portion), and a bypass diode device was fabricated. This device was then attached to a solar panel to create a solar cell module.
[0115] All solar cell modules incorporating the bypass diode device had the same thickness, eliminating the protrusions caused by conventional junction boxes. The design ensured that even when mounted on a car roof, no parts would protrude into the vehicle.
[0116] Furthermore, a deflection test was performed on the ceramic substrate used in the fabricated sample using an autograph. The deflection test involved fixing the periphery of the fabricated bypass diode circuit board and pressing on the central region where the conductor was located.
[0117] In all samples, the conductive portion took on a concave shape, and the bending of the ceramic substrate was confirmed. This demonstrated that the solar cell module can be installed to conform to the curved surface of a car roof.
[0118] Furthermore, this technology can also take the following configurations: (1) A circuit board for a bypass diode having a ceramic substrate and a conductor, wherein the conductor is arranged in an isolated island-like manner in the central region of the main surface of the ceramic substrate, the conductor has a first electrode portion and a second electrode portion, the first electrode portion has a bypass diode installed on it and electrically connects the bypass diode, and the second electrode portion is the region of the conductor excluding the first electrode portion. (2) The circuit board for a bypass diode according to (1), wherein the area of the first electrode portion is larger than the area of the adhesive surface of the bypass diode. (3) The circuit board for a bypass diode according to (1) or (2), wherein the ceramic substrate has a space inside that overlaps with the conductor in a plan view. (4) A bypass diode circuit board comprising a ceramic substrate and a conductor, wherein the conductor has a first electrode portion and a second electrode portion arranged in an isolated island-like manner in close proximity to each other in the central region of the main surface of the ceramic substrate, and one of the first electrode portion and the second electrode portion serves as a mounting portion for a bypass diode. (5) A bypass diode circuit board according to any one of (1) to (4), wherein the ceramic substrate is black in color and white in color. (6) A bypass diode circuit board according to any one of (1) to (5), wherein the ceramic substrate has a ridge portion, and the ridge portion is arranged on the peripheral edge of the ceramic substrate so as to surround the mounting portion for the conductor and the bypass diode in a circumferential manner. (7) A bypass diode circuit board according to (6), wherein the ridge portion has a stepped structure with one step portion, and the step portion has a conductive film. (8) A bypass diode circuit board according to any one of (1) to (7), wherein the conductor has a portion that penetrates the ceramic substrate in the thickness direction. (9) A bypass diode device having the bypass diode on a bypass diode circuit board according to any one of (1) to (8). (10) A solar cell module having 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 arranged in the order of a first film, a transparent resin layer, a solar cell, a white resin layer, and a second film, and the bypass diode device is housed within the thickness range of the solar cell panel.
[0119] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.
[0120] 1 Bypass diode device 2 Solar cell module 11 Circuit board for bypass diode 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 surface 111ac Central region 111b Ridge portion 111e Main body 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 Cover 121 Bonding material 231 Series cell group 231a Cell
Claims
1. A circuit board for a bypass diode, comprising a ceramic substrate and a conductor, wherein the conductor is arranged in an isolated island-like manner in the central region of the main surface of the ceramic substrate, the conductor has a first electrode portion and a second electrode portion, the first electrode portion has a bypass diode installed on it and electrically connects the bypass diode, and the second electrode portion is the region of the conductor excluding the first electrode portion.
2. The circuit board for a bypass diode according to claim 1, wherein the area of the first electrode portion is larger than the area of the adhesive surface of the bypass diode.
3. The circuit board for a bypass diode according to claim 1 or 2, wherein the ceramic substrate has a space inside that overlaps with the conductor in a plan view.
4. A circuit board for a bypass diode, comprising a ceramic substrate and a conductor, wherein the conductor has a first electrode portion and a second electrode portion arranged in an isolated island-like manner in close proximity to each other in the central region of the main surface of the ceramic substrate, and one of the first electrode portion and the second electrode portion serves as a mounting portion for a bypass diode.
5. The circuit board for a bypass diode according to any one of claims 1 to 4, wherein the ceramic substrate has a color tone that is either black or white.
6. The circuit board for a bypass diode according to any one of claims 1 to 5, wherein the ceramic substrate has a ridge portion, and the ridge portion is arranged on the peripheral edge of the ceramic substrate so as to surround the mounting portion for the conductor and the bypass diode in a circumferential manner.
7. The circuit board for a bypass diode according to claim 6, wherein the embankment portion has a stepped structure having one step portion, and the step portion has a conductive film.
8. The circuit board for a bypass diode according to any one of claims 1 to 7, wherein the conductor has a portion that penetrates the ceramic substrate in the thickness direction.
9. A bypass diode device having the bypass diode on a circuit board for a bypass diode according to any one of claims 1 to 8.
10. A solar cell module comprising the bypass diode device described in claim 9 and a solar cell panel.
11. The solar cell module according to claim 10, wherein the solar cell panel is arranged in the order of a first film, a transparent resin layer, a solar cell, a white resin layer, and a second film, and the bypass diode device is housed within the thickness range of the solar cell panel.