A process for the preparation of a photovoltaic device

Abstract

The application provides a photovoltaic device preparation process, comprising the following steps: S1: using a 0.25mm thick pure copper sheet, the copper sheet is welded and attached to an aluminum heat sink through a welding process at 450 DEG C; S2: a bypass diode and a terminal seat are welded and attached to a circuit substrate through SMT with high-temperature tin paste; S3: a chip is fixed and wired and packaged with silver paste, and the chip is solidified with the circuit substrate for 175 DEG C for two hours; S4: 138 DEG C low-temperature tin paste is uniformly coated on the copper sheet on the aluminum heat sink through a stainless steel tin paste net, and the copper sheet is passed through a reflow soldering furnace; S5: the reflow soldering furnace is preheated; S6: the battery module is fixed on the copper sheet on the aluminum heat sink which has been coated with low-temperature tin paste in advance, and is overheated for 10 minutes in the reflow soldering furnace. The application overcomes the problem that the traditional battery module and the heat sink are combined through heat-conducting silica gel, and holes are easily formed, heat is concentrated, heat conduction is blocked, and power generation efficiency is affected, and the process is simple and low in cost.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, specifically a photovoltaic device manufacturing process. Background Technology

[0002] Photovoltaic power generation is a technology that directly converts light energy into electrical energy using the photovoltaic effect at the semiconductor interface. Photovoltaic cells have advantages such as being unaffected by building orientation, having a long exposure time to sunlight, and minimizing shading interference.

[0003] In existing technologies, photovoltaic cell module packaging uses COB (Chip On Board). Due to limitations in packaging production equipment and the welding temperature restrictions during component soldering in the production process, the only method that can be used is to first solder the module circuit board, bypass diodes, and terminal blocks using medium-high temperature solder paste in the SMT method, and then encapsulate the photovoltaic chip with silver paste (85% silver content) for die bonding and wire bonding, followed by curing at 175°C for two hours. To avoid the silver paste at the cell chip bonding area melting due to excessively high solder melting point, which could cause the chip and gold wire to loosen, resulting in displacement and functional structural damage, the entire process must be segmented. In addition, it is also limited by the working size of the packaging equipment on the market and the size of the cell, resulting in low production efficiency and high scrap rate of photovoltaic cells.

[0004] Traditionally, gallium arsenide (GaAs) solar cell modules are combined with heat sinks using thermally conductive silicone pads. However, this often results in the formation of pores that concentrate heat, hindering heat conduction and affecting power generation efficiency. For example, a Chinese utility model patent with authorization announcement number CN 207083051 U and authorization announcement date of March 9, 2018, discloses a heat sink fixing device for low-concentration photovoltaic panels. The device includes a glass plate and a silicon cell. The glass plate is fixed to the front of the silicon cell, and a thermally conductive silicone pad is provided on its back. The heat sink is adhered to the thermally conductive silicone pad. The outer side of the heat sink has corresponding left and right bracket connectors. Bolt holes are welded to the outer side of the bracket connectors. Corresponding U-shaped connecting pieces are evenly distributed on the upper and lower sides of the bracket connectors. The bottom surface of the U-shaped connecting piece is in close contact with the upper and lower surfaces of the heat sink, and a fixing screw is provided at the corresponding position for fixing. The upper part of one end of the U-shaped connecting piece is fixed to the upper and lower edges of the glass plate through a slot, and the other end is connected to a pressure plate through a fastening bolt. The pressure plate is pressed tightly against the outer side of the heat sink.

[0005] In concentrated photovoltaic gallium arsenide (GaAs) battery modules, the ideal combination with a heat sink is to minimize the intermediate thermal resistance, which is achieved through welding. Copper has the best thermal conductivity, but for cost reasons, aluminum heat sinks are used instead. However, the welding temperature of copper-aluminum alloys is too high (450°C), which can cause the chip and upper component weld points to melt. The temperatures of each weld point are as follows: chip and substrate 175°C, diode and terminal block and substrate 245°C. To meet the minimum temperature requirements, the temperature of the substrate and heat sink needs to be controlled below 150°C. Therefore, a low-temperature manufacturing process for photovoltaic devices is needed. Summary of the Invention

[0006] To overcome the aforementioned problems in the existing technology, the purpose of this invention is to provide a photovoltaic device manufacturing process with high power generation efficiency and low manufacturing cost.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a photovoltaic device manufacturing process, wherein the process involves a battery module and an aluminum heat sink, the battery module comprising a bypass diode, a terminal block, a chip, and a circuit board; comprising the following steps:

[0008] S1: A 0.25mm thick pure copper sheet is used, and the copper sheet is welded to the aluminum heat sink at 450℃ using a welding process.

[0009] S2: The bypass diode and terminal block are soldered to the circuit board using SMT method with 245℃ medium and high temperature solder paste;

[0010] S3: The chip is die bonded and wire bonded with silver paste, and then the chip and the circuit board are cured at 175°C for two hours to form a battery module.

[0011] S4: Using 138℃ low-temperature solder paste, apply it evenly to the copper fins of the aluminum heat sink pre-soldered through a stainless steel solder paste mesh, and then pass it through an eight-section reflow oven.

[0012] S5: Preheat the reflow oven for 60 minutes;

[0013] S6: The battery module is fixed onto the copper sheet on the aluminum heat sink that has been pre-coated with low-temperature solder paste using a clamp, and then overheated in a reflow oven for 10 minutes to achieve a low-temperature soldering effect.

[0014] It should be noted that the preheating time of the reflow oven varies depending on the machine model.

[0015] The present invention is further configured such that the circuit board is a copper circuit board.

[0016] The present invention is further configured such that: a circuit board is provided with pads, the pads including a negative pad and a positive pad, and the battery assembly is connected to the negative pad and the positive pad.

[0017] The present invention is further configured such that: the battery assembly includes a battery chip, a packaging line and a packaging shell, the packaging line is connected to both ends of the battery chip, the battery chip is disposed inside the packaging shell, and the packaging shell is connected to the upper surface of the module circuit board.

[0018] The present invention is further configured such that: the number of terminal blocks is two, and they are arranged on the diagonal of the circuit board.

[0019] The present invention is further configured such that the silver paste mentioned in step S3 has a silver content of 85%.

[0020] The present invention is further configured such that the maximum temperature of the reflow oven in step S4 is 150°C.

[0021] The present invention is further configured such that: during welding, the heat sink needs to be kept warm to different degrees according to the size of the heat sink. For example, for a 200g heat sink, the heat preservation temperature needs to be controlled at 380℃.

[0022] Based on the calculation of temperature loss due to heat dissipation surface area, the heat dissipation effect of a heat sink is affected by many factors such as size, surface area, and material. It is necessary to ensure that the temperature lost by the heat sink is lower than the melting point of the solder paste when soldering is required for the soldering process to be carried out. Here, the ambient temperature of the hot air box is raised to the melting point of the solder paste, which also serves to keep the heat sink warm and prevent the soldering operation from being impossible due to temperature loss.

[0023] The present invention is further configured such that the surface temperature of the solder pads of the circuit board is controlled at 138°C, and once the low-temperature solder paste reaches its melting point, the heat source must be removed and the temperature lowered immediately.

[0024] The present invention is further configured such that: during soldering, a positioning method must be used to ensure that the chip position on the soldering surface is aligned with the center of the heat sink. Any of the following positioning methods can be used, but the first method is generally the most convenient.

[0025] 1. The chip can be positioned by milling recesses of length, width, and depth into the surface to be welded.

[0026] 2. The dimensions of the packaged chip (length, width, height) are milled onto the surface to be soldered. The chip can then be positioned using the tension during soldering.

[0027] 3. Set mark points and crosshair axis positioning on the chip package.

[0028] In summary, the beneficial effects of the above-mentioned technical solution of the present invention are as follows:

[0029] 1. This invention overcomes the problem that traditional concentrated photovoltaic gallium arsenide battery modules and heat sinks are bonded together with thermally conductive silicone, which easily forms holes and heat concentration, causing heat conduction obstruction and affecting power generation efficiency. It adopts low-temperature welding to minimize intermediate thermal resistance and ensure power generation efficiency.

[0030] 2. The process of this invention is simple and the cost is low.

[0031] 3. In long-term desert and Gobi environments and harsh conditions, the welding process used in this invention is more reliable and safer than the traditional thermally conductive silicone bonding method. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is an isometric view of an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the battery module structure of the present invention;

[0035] Figure 3 This is a partial schematic diagram of the welding position in an embodiment of the present invention;

[0036] Figure 4 This is a process flow diagram of an embodiment of the present invention.

[0037] The attached diagram lists the components represented by each number as follows:

[0038] 1-Battery module, 11-Battery assembly, 12-Terminal socket, 13-Bypass diode, 14-Copper circuit board, 2-Copper sheet, 3-Aluminum heat sink. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0040] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0041] Example 1:

[0042] Figure 4 This is a schematic diagram of the process flow of a preferred embodiment of the present application. A photovoltaic device manufacturing process includes the following steps:

[0043] S1: A 0.25mm thick pure copper sheet 2 is used, and the copper sheet 2 is welded to the aluminum heat sink 3 at 450℃ using a welding process;

[0044] S2: The bypass diode 13 and the terminal block 12 are soldered to the circuit board 14 using SMT method with 245°C medium and high temperature solder paste.

[0045] S3: The chip is die-bonded and wire-bonded with silver paste (85% silver content) to form battery assembly 11. Then the chip and the circuit board 14 are cured at 175°C for two hours to form battery module 1.

[0046] S4: Using 138℃ low-temperature solder paste, apply it evenly to the copper sheet 2 pre-soldered on the aluminum heat sink 3 through a stainless steel solder paste mesh, and then pass it through an eight-section reflow oven; the maximum temperature of the reflow oven is 150℃.

[0047] S5: Preheat the reflow oven for 60 minutes;

[0048] S6: The battery module 1 is fixed onto the copper sheet 2 on the aluminum heat sink 3, which has been pre-coated with low-temperature solder paste, using a clamp. After being overheated in a reflow oven for 10 minutes, a low-temperature soldering effect is achieved.

[0049] During welding, the heat sink needs to be insulated to different degrees according to its size. For a 200g heat sink, the insulation temperature needs to be controlled at 380℃.

[0050] The surface temperature of the solder pads on the circuit board is controlled at 138°C. Once the low-temperature solder paste reaches its melting point, the heat source must be removed immediately and the surface cooled. During soldering, positioning techniques must be used to ensure that the chip position on the soldering surface is aligned with the center of the heat sink.

[0051] Example 2:

[0052] like Figures 1-3 The image shown illustrates a preferred embodiment of the process described in this application. The apparatus involved in the process includes a battery module 1 and an aluminum heat sink 3. (The image shows a 5mm diameter...) Take a 5mm battery chip and a 200g aluminum heat sink as an example.

[0053] like Figure 2 As shown, the battery module 1 includes a bypass diode 13, a terminal block 12, a battery assembly 11, and a circuit board 14; the circuit board 14 is a copper circuit board.

[0054] The copper circuit board 14 is provided with pads, including negative pads and positive pads, and the battery assembly 11 is connected to the negative pads and positive pads.

[0055] The battery assembly 11 includes a battery chip, encapsulation wires, and an encapsulation housing. The encapsulation wires are connected to both ends of the battery chip, which is disposed inside the encapsulation housing. The encapsulation housing is connected to the upper surface of the copper circuit board 14. Two terminal blocks 12 are provided, positioned diagonally on the copper circuit board 14.

[0056] S1: A 0.25mm thick pure copper sheet 2 is used, and the copper sheet 2 is welded to the aluminum heat sink 3 at 450℃ using a welding process.

[0057] S2: The bypass diode 13 and the terminal block 12 are soldered to the circuit board 14 using SMT method with 245°C medium and high temperature solder paste.

[0058] S3: The chip is die-bonded and wire-bonded with silver paste (85% silver content) to form battery assembly 11. Then the chip and the circuit board 14 are cured at 175°C for two hours to form battery module 1.

[0059] S4: Using 138℃ low-temperature solder paste, apply it evenly to the copper sheet 2 pre-soldered on the aluminum heat sink 3 through a stainless steel solder paste mesh, and then pass it through an eight-section reflow oven; the maximum temperature of the reflow oven is 150℃.

[0060] S5: Preheat the reflow oven for 60 minutes;

[0061] S6: The battery module 1 is fixed onto the copper sheet 2 on the aluminum heat sink 3, which has been pre-coated with low-temperature solder paste, using a clamp. After being overheated in a reflow oven for 10 minutes, a low-temperature soldering effect is achieved.

[0062] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A photovoltaic device manufacturing process, the process involving an apparatus including a battery module and an aluminum heat sink, the battery module including a bypass diode, a terminal block, a battery assembly, and a circuit board; characterized in that, Includes the following steps: S1: A 0.25mm thick pure copper sheet is used, and the copper sheet is welded to the aluminum heat sink at 450℃. During welding, the heat sink needs to be kept at different temperatures according to its size. For example, for a 200g heat sink, the temperature needs to be controlled at 380℃. During welding, positioning methods must be used to ensure that the chip position on the bonding surface is consistent with the center of the heat sink. S2: The bypass diode and terminal block are soldered to the circuit board using SMT method with 245℃ medium and high temperature solder paste; S3: The chip is die-bonded and wire-bonded with silver paste to form a battery assembly. The chip and the circuit board are then cured at 175°C for two hours to form a battery module. S4: Using 138℃ low-temperature solder paste, apply it evenly to the copper fins of the aluminum heat sink pre-soldered through a stainless steel solder paste mesh, and then pass it through an eight-section reflow oven with a maximum temperature of 150℃. S5: Reflow oven preheating; S6: Fix the battery module onto the copper sheet on the aluminum heat sink that has been pre-coated with low-temperature solder paste using a clamp. After being overheated in a reflow oven for 10 minutes, a low-temperature soldering effect is achieved. The surface temperature of the solder pads on the circuit board is controlled at 138°C. Once the low-temperature solder paste reaches its melting point, the heat source must be removed immediately and the temperature lowered.

2. The photovoltaic device manufacturing process according to claim 1, characterized in that, The circuit board is a copper circuit board.

3. The photovoltaic device manufacturing process according to claim 1, characterized in that, The circuit board is provided with pads, including negative pads and positive pads, and the battery assembly is connected to the negative pads and positive pads.

4. The photovoltaic device manufacturing process according to claim 1, characterized in that, The battery assembly includes a battery chip, a packaging line, and a packaging shell. The packaging line is connected to both ends of the battery chip, the battery chip is disposed inside the packaging shell, and the packaging shell is connected to the upper surface of the circuit board.

5. The photovoltaic device manufacturing process according to claim 1, characterized in that, The number of terminal blocks is two, and they are arranged on the diagonal of the circuit board.

6. The photovoltaic device manufacturing process according to claim 1, characterized in that, The silver paste mentioned in step S3 has a silver content of 85%.

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