JP2000277785A - Bypass diode for solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bypass diode for a solar battery which can protect a diode chip by reducing the pressure from the outside. SOLUTION: A bypass diode is constituted by joining lead terminals 231 and 232 consisting of copper foil each via junction material 220 to the surface and the rear of a diode chip 210. Copper plates are joined to the regions excluding the chip junction parts of the lead terminals 231 and 232, so that the topside and the down side of the bypass diode are substantially flush. The thickness of the copper plate is made substantially the same as the thickness of the diode chip 210 which includes the lead terminal 231 and the junction material 220.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bypass diode for a solar cell module for connecting a plurality of solar cells to a solar cell module connected in series and bypassing a reverse bias to the solar cell.

[0002]

2. Description of the Related Art In recent years, the use of fossil fuels such as petroleum has raised the problem of an increase in atmospheric CO ₂ concentration. Since CO ₂ transmits sunlight but absorbs infrared radiation from the surface, there is a concern that global warming will rapidly progress in the near future due to a phenomenon called greenhouse effect. For this reason, efforts are being made worldwide to reduce CO ₂ emissions.

[0003] Emissions from thermal power generation in particular account for a large proportion as a source of CO ₂ , and there is a strong demand for practical use of alternative clean energy. Of these, solar power generation is not only a clean energy source, it also has safety features, and it can be installed in private homes to generate power for use in homes and businesses. Demand is expected to grow.

A solar cell installed on the roof of a building or a roof of a house and used for power generation cannot output sufficient electric power with only one solar cell (hereinafter, referred to as a cell). It is used as a solar cell module in which a plurality of cells are connected in series.

[0005] However, in such a solar cell module, when the sunlight to some of the cells is blocked by the fallen leaves or the shadow of the utility pole and the cells stop generating power, the shaded cells are biased in the reverse direction. If the reverse bias exceeds the withstand voltage of the cell, the cell may be broken and the power generation performance of the solar cell module may be reduced.

For this reason, Japanese Unexamined Patent Publication No. Hei 5-2916029 discloses a bypass diode for connecting a diode in the direction opposite to the direction of the electromotive force of each solar cell connected in series and bypassing the reverse bias of the cell. A solar cell module having a different configuration is disclosed.

FIG. 3 is an equivalent circuit diagram of a solar cell module with a bypass diode. For a solar cell module in which four cells 120 are connected in series, one bypass diode 200 is connected in parallel in the reverse direction for each cell 120. With such a configuration, even when the electromotive force of some cells is stopped, the cells are not biased in the reverse direction and are not destroyed.

FIGS. 4A and 4B are schematic views of a conventional bypass diode. FIG. 4A is a top view and FIG. 4B is a front view. The lead terminals 231 and 2 are provided on the front and back surfaces of the diode chip 210 via a bonding material 220 such as cream solder.
32 are joined. The lead terminals 231 and 232 are made of a foil material having good electrical conductivity such as copper foil, and have a thickness of about 0.1 mm.
The thickness of the diode chip 210 is about 0.4 mm including the thickness of the bonding material 220, and the thickness t of the entire bypass diode is about 0.6 mm.

FIG. 5 is an enlarged front view of a part of a solar cell module with a bypass diode. A bypass diode 200 is attached adjacent to a cell (not shown) formed on a conductive substrate 110 such as stainless steel. The lead terminal 231 bonded to the back surface of the diode chip 210 is bonded on the conductive substrate 110 and connected to a cell surface electrode (not shown), and the lead terminal 232 bonded to the surface of the diode chip 210 is mounted on the conductive substrate 110. And is connected to a cell back surface electrode (not shown). The upper surface of the conductive substrate 110 is covered with a transparent material 130 such as a transparent resin or a glass plate for protecting cells (not shown), the bypass diode 200 and the like.

[0010]

In the above-described solar cell module, only the chip junction of the bypass diode joined on the conductive substrate protrudes.
The diode chip may be damaged when the diode chip is directly subjected to the pressure from the permeable material that covers the diode chip.

Also, when forming the lead terminal of the bypass diode during the manufacturing process, the bending stress received by the lead terminal is transmitted to the chip bonding portion, and the diode chip may peel off from the lead terminal or damage the diode chip itself. There is.

An object of the present invention is to provide a bypass diode for a solar cell module capable of protecting a diode chip by reducing the pressure applied to the bypass diode from the outside. Aim.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a diode for a solar cell module in which lead terminals made of a metal foil material are bonded to the front and back surfaces of a diode chip via a bonding material. Then, a metal material is bonded to a region except for a diode chip bonding portion of a lead terminal so that an upper surface and a lower surface of the bypass diode are substantially flush with each other. The thickness of the metal material was substantially the same as the sum of the thickness of the lead terminal and the thickness of the diode chip including the bonding material.

According to the present invention, since the pressure applied to the bypass diode from the outside can be reduced, the bypass diode can be protected.

That is, by making the upper and lower surfaces of the bypass diode substantially the same plane, pressure from the transparent material is applied not only to the chip junction but also to the entire lead terminal. Therefore, the pressure applied to the chip joint can be reduced, and chip damage can be prevented.

Further, since the thickness of the lead terminal other than the chip bonding portion is increased by the metal material, the influence of stress applied to the lead terminal by external pressure can be prevented.

Further, since it is not necessary to form the lead terminals, no stress is applied to the diode chip and the bonding material.

Further, by joining the metal plate to the lead terminal, it is possible to secure a cross-sectional area enough to cope with the current density and to reduce the resistance loss.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B are schematic views of a bypass diode according to an embodiment of the present invention, wherein FIG. 1A is a front view, and FIG. 1B is a partially enlarged front view.

As shown in FIG. 1A, lead terminals 231 and 2 made of a copper foil material are provided on the front and back surfaces of a diode chip 210 via a bonding material 220 such as cream solder.
32 are joined to form a bypass diode. A bonding material made of solder is provided on the upper surface of the lead terminal 231 bonded to the back surface of the diode chip 210 and the lower surface of the lead terminal 232 bonded to the surface of the diode chip 210 such that the upper surface and the lower surface of the bypass diode are substantially flush. A copper plate 240 is joined via 220.

As shown in FIG. 1B, the thickness of the copper plate 240 including the thickness of the bonding material 220 is substantially the same as the thickness of the diode chip 210 including the bonding material 220. In the present embodiment, the thickness a of the copper plate 240 including the thickness of the bonding material 220 is about 0.5 mm,
31 and 232 have a thickness b of about 0.1 mm;
The thickness “c” of the diode chip 210 including the thickness of “.
The thickness t of the bypass diode is about 0.6 mm.

FIG. 2 is an enlarged front view of a part of the solar cell module with a bypass diode according to the present embodiment. A bypass diode 200 is attached adjacent to a cell (not shown) formed on a conductive substrate 110 such as stainless steel. The lead terminal 231 joined to the lower surface of the diode chip 210 is joined on the conductive substrate 110, connected to a cell surface electrode (not shown), and the lead terminal 232 joined to the upper surface of the diode chip 210 is attached to the conductive substrate 110. And is connected to a cell back electrode (not shown). Conductive substrate 1
10 has a cell (not shown) and a bypass diode 2
00 and the like are covered with a transparent material 130 such as a transparent resin or a glass plate for protecting the transparent resin.

Since the upper and lower surfaces of the bypass diode are substantially flush with each other, pressure from the transparent material 130 such as a glass plate is applied not only to the chip junction but also to the entire surface of the bypass diode. For this reason, the pressure applied to the chip joining portion can be reduced, and chip breakage and chip peeling can be prevented.

In this embodiment, the copper plate is joined to the lead terminals. However, the same effect can be obtained by using a deformed material in which only the ends of the metal material are formed thin.

[0026]

As described above, according to the present invention, the pressure applied to the diode chip from the outside can be reduced, and chip damage and chip peeling can be prevented.

Further, it is possible to secure a cross-sectional area of the lead terminal which can sufficiently cope with the current density, and to reduce the resistance loss.

Therefore, the bypass diode can be protected, and the power generation characteristics of the solar cell module do not deteriorate.

[Brief description of the drawings]

FIG. 1A is a front view of a bypass diode according to an embodiment of the present invention. FIG.

FIG. 2 is a partially enlarged front view of a solar cell module according to an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of a solar cell module.

FIG. 4A is a top view of a conventional bypass diode, and FIG.

FIG. 5 is a partially enlarged front view of a conventional solar cell module.

[Explanation of symbols]

 110 conductive substrate 120 solar cell 130 permeable material 200 bypass diode 210 diode chip 220 bonding material 231 lead terminal 232 lead terminal 240 copper plate

Claims (3)

[Claims] 1. A bypass diode for a solar cell module in which lead terminals made of a metal foil material are bonded to the front and back surfaces of a diode chip via a bonding material, respectively, wherein an upper surface and a lower surface of the bypass diode are substantially flush with each other. A bypass diode for a solar cell module, wherein a metal plate is bonded to a region of the lead terminal except for a diode chip bonding portion. 2. The bypass diode for a solar cell module according to claim 1, wherein the thickness of the metal plate is substantially the same as the sum of the thickness of the lead terminal and the thickness of the diode chip including the bonding material. 3. The bypass diode for a solar cell module according to claim 1, wherein a copper plate is joined via solder to a region of the lead terminal made of a copper foil material except for a diode chip joint.