A ceramic metallized silicon photovoltaic cell and a method for processing the same

Abstract

The application relates to the technical field of silicon photocells, in particular to a ceramic metalized silicon photocell and a processing method thereof. The ceramic metalized silicon photocell comprises a base seat formed by sintering aluminum oxide ceramic and metal copper, a counterbore is formed at the top of the base seat, a copper ring formed by punching an oxygen-free copper foil is mounted on the counterbore, and a copper oxide film layer is formed on the surface of the copper ring; the base seat is formed with a chip groove, a control chip is mounted in the chip groove, a metal electrode is brazed to the copper ring, the inner end of the metal electrode is inserted into the chip groove, and the inner end of the metal electrode is signal-connected with the control chip; the aluminum oxide ceramic and the copper are fully infiltrated and combined with each other in a high-temperature sintering process, the interface bonding strength is large, and the aluminum oxide ceramic and the copper are not prone to delamination, cracking or falling off, the structural strength, vibration resistance and high-temperature resistance of the silicon photocell are greatly improved, the product can still be stably operated for a long time under complex working conditions, and the overall stability of the silicon photocell is further improved.

Description

Technical Field

[0001] This invention relates to the field of silicon photovoltaic technology, and in particular to a ceramic-metallized silicon photovoltaic cell and its processing method. Background Technology

[0002] Silicon photovoltaic cells, as a type of semiconductor device that converts light energy into electrical energy, belong to the category of rectifier optical devices and are widely used in various optical instruments, such as spectrophotometers, colorimeters, whiteness meters, illuminance meters, luminance meters, colorimeters, optical power meters, flame detectors, and color magnifiers. When light energy shines on the PN junction of the semiconductor, the intensity of the light energy is converted into a certain current and voltage, which are output through two Kovar alloy electrodes on black ceramic. Therefore, the reliability and stability of the electrodes determine the performance of the silicon photovoltaic cell.

[0003] Currently, the ceramic electrodes used in silicon photovoltaic cells generally adopt the molybdenum-manganese metallization method, which involves printing an electronic paste made of metallic molybdenum, metallic manganese, and glass powder onto the required electrode areas of the ceramic, followed by high-temperature sintering and electroplating with nickel to form a metallization layer.

[0004] The metal layer produced by the molybdenum-manganese metallization method involves the physical infiltration of liquid glass into the pores of ceramics. Since ceramics of different purities have varying porosities, higher purity ceramics have fewer pores, resulting in less liquid glass penetration. Furthermore, the metal layer is fabricated using a printing method, resulting in a thickness of only 10-20 micrometers. During sintering, the flow of liquid glass makes it difficult to guarantee the uniformity of the metal layer, leading to poor stability and adhesion. This often fails to meet the stringent operating conditions of silicon photovoltaic cells. Summary of the Invention

[0005] The purpose of this invention is to provide a solution that addresses the shortcomings of existing technologies.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A ceramic-metallized silicon photovoltaic cell includes a substrate formed by sintering alumina ceramic and metallic copper. A countersunk hole is formed on the top of the substrate, and a copper ring formed by stamping oxygen-free copper foil is installed in the countersunk hole. A copper oxide thin film layer is formed on the surface of the copper ring. A chip slot is formed in the substrate, and a control chip is installed in the chip slot. A metal electrode is brazed to the copper ring, and the inner end of the metal electrode is inserted into the chip slot and is signal-connected to the control chip.

[0007] Furthermore: a metal wire is installed inside the metal electrode, and the other end of the metal wire is electrically connected to the control chip.

[0008] Furthermore: the depth of the countersink is 200-300 micrometers.

[0009] Furthermore: the thickness of metallic copper is 10-20 micrometers.

[0010] A method for fabricating a ceramic-metallized silicon photovoltaic cell includes the following steps; Step 1: Alumina dry powder is pressed into a matrix shape, and then sintered at 1150-1300℃ for 2-4 hours to form a matrix base; Step 2: Select oxygen-free copper foil with a thickness of 200-300 micrometers and stamp it into a matching copper ring according to the size of the metal electrode; Step 3: Pre-oxidize the copper ring and the substrate separately, and a thin film of copper oxide will be formed on the surface of the copper ring; Step 4: Assemble the copper ring and the base. Assemble the copper ring into the base where countersunk holes for the metal electrodes need to be made. Step 5: The copper ring and the base are fused and sintered at a temperature of 1066-1083℃ and an oxygen content of 0.2%-0.8%, so that the copper and alumina ceramic undergo a eutectic reaction and produce Cu(AlO2)2 and Cu(AlO2) composite oxides. Step 6: Insert the metal electrode into the pre-drilled hole on the substrate base, and braze the metal electrode to the copper ring together with the help of silver-copper solder to form the base of the silicon photovoltaic cell; Step 7: Attach the control chip to the base and use gold wire to bond the PN terminals of the control chip to the two metal electrodes of the base. Step 8: After sealing the base with epoxy resin, the product is considered a finished product once it passes the test.

[0011] Furthermore, in step one, sintering aids such as CuO, Nb2O5, TiO2, and Na2O / K2O are added to lower the sintering temperature.

[0012] The beneficial effects of this invention are that alumina ceramics and copper fully penetrate each other and have a high bonding rate during high-temperature sintering, resulting in strong interfacial bonding and making them less prone to delamination, cracking, or detachment. This significantly improves the structural strength, vibration resistance, and high-temperature resistance of silicon photovoltaic cells, enabling the product to maintain long-term stable operation under complex working conditions and further enhancing the overall stability of silicon photovoltaic cells.

[0013] The substrate features a countersunk hole at the top, enabling precise positioning and limiting of the copper ring formed by stamping oxygen-free copper foil. This ensures accurate installation and high flatness of the copper ring, facilitating subsequent assembly and welding of the metal electrodes and improving the consistency and yield rate of mass production. The copper oxide film layer formed on the surface of the copper ring enhances wettability and adhesion with the brazing filler metal, improving the brazing strength and conductivity reliability between the metal electrode and the copper ring. Simultaneously, the copper oxide layer inhibits oxidation and corrosion of the copper ring, extending the service life of the electrode connection. The metal electrode and copper ring are fixed by brazing, resulting in low contact resistance and excellent conductivity. The inner end of the electrode extends into the chip slot and directly connects to the control chip, achieving stable and low-loss electrical signal transmission, ensuring rapid response and reliable operation of the silicon photovoltaic cell. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention.

[0015] Figure 2 This is a process flow diagram.

[0016] The reference numerals in the figures include: 1-Base base 11-Counterhole, 12-Copper ring, 13-Chip slot, 14-Control chip, 15-Metal electrode, 16-Metal wire 17-Silver-copper solder. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figure 1 The ceramic-metallized silicon photovoltaic cell shown includes a substrate 1 formed by sintering alumina ceramic and copper. A countersunk hole 11 is formed on the top of the substrate 1, and a copper ring 12 formed by stamping oxygen-free copper foil is installed in the countersunk hole 11. A copper oxide thin film layer is formed on the surface of the copper ring 12. A chip groove 13 is formed in the substrate 1, and a control chip 14 is installed in the chip groove 13. A metal electrode 15 is brazed to the copper ring 12, and the inner end of the metal electrode 15 is inserted into the chip groove 13 and is signal-connected to the control chip 14.

[0019] During the high-temperature sintering process, alumina ceramics and copper fully penetrate each other, resulting in a high bonding rate and strong interfacial bonding strength. This makes them less prone to delamination, cracking, or detachment, significantly improving the structural strength, vibration resistance, and high-temperature resistance of silicon photovoltaic cells. This allows the products to maintain long-term stable operation under complex working conditions, further enhancing the overall stability of silicon photovoltaic cells.

[0020] The substrate has a countersunk hole 11 at the top, which can accurately position and limit the copper ring 12 formed by stamping oxygen-free copper foil, ensuring that the installation position of the copper ring 12 is accurate and the flatness is high. This is beneficial to the subsequent assembly and welding of the metal electrode 15, and improves the consistency and yield of mass production. The copper oxide film layer formed on the surface of the copper ring 12 can enhance the wettability and bonding force with the brazing filler metal, and improve the brazing strength and conductivity reliability between the metal electrode 15 and the copper ring 12. At the same time, the copper oxide layer can inhibit the oxidation and corrosion of the copper ring 12, and extend the service life of the electrode connection part. The metal electrode 15 and the copper ring 12 are fixed by brazing, with low contact resistance and excellent conductivity. The inner end of the electrode extends into the chip slot 13 and is directly connected to the control chip 14 to achieve stable and low-loss electrical signal transmission, ensuring that the silicon photovoltaic cell responds quickly and works reliably.

[0021] Furthermore, a metal wire 16 is installed inside the metal electrode 15, and the other end of the metal wire 16 is electrically connected to the control chip 14. Using the metal wire 16 to achieve the conductive connection between the electrode and the control chip 14 can effectively buffer the mechanical stress caused by assembly, thermal expansion and vibration, and avoid problems such as chip cracking under stress and electrode damage to the chip.

[0022] Furthermore, the depth of the countersunk hole 11 is 200-300 micrometers. The moderate depth of the countersunk hole 11 of 200-300 micrometers can effectively limit the circumferential and axial movement of the copper ring 12 formed by stamping oxygen-free copper foil, ensuring that the copper ring 12 is installed in a precise position without deviation or tilting, thereby improving the overall assembly accuracy and consistency.

[0023] Furthermore, the thickness of the metallic copper is 10-20 micrometers. This thickness is highly matched with the sintering shrinkage rate of the alumina ceramic, which can avoid thermal expansion mismatch and interface cracking caused by excessive copper layer thickness during high-temperature co-firing, or insufficient penetration and reduced bonding strength caused by excessive copper layer thickness. This ensures that the ceramic and copper form a dense metallurgical bond, taking into account both bonding strength and structural integrity.

[0024] A method for fabricating a ceramic-metallized silicon photovoltaic cell includes the following steps; Step 1: Alumina dry powder is pressed into a matrix shape, and then sintered at 1150-1300℃ for 2-4 hours to form the matrix base 1; Step 2: Select oxygen-free copper foil with a thickness of 200-300 micrometers and stamp it to form a matching copper ring 12 according to the size of the metal electrode 15; Step 3: Pre-oxidize the copper ring 12 and the substrate 1 respectively, and a copper oxide film will be generated on the surface of the copper ring 12; Step 4: Assemble the copper ring 12 and the base 1. Assemble the copper ring 12 into the countersunk hole 11 of the base 1 where the metal electrode 15 needs to be made. Step 5: The copper ring 12 and the base 1 are fused and sintered at a temperature of 1066-1083℃ and an oxygen content of 0.2%-0.8%, so that the copper and alumina ceramic undergo a eutectic reaction and produce Cu(AlO2)2 and Cu(AlO2) composite oxides. Step 6: Insert the metal electrode 15 into the pre-drilled countersunk hole 11 on the substrate base 1, and braze the metal electrode 15 to the copper ring 12 together with the silver-copper solder 17 to form the base of the silicon photovoltaic cell. Step 7: Attach the control chip 14 to the base and use gold wire to bond the PN ends of the control chip 14 to the two metal electrodes 15 of the base. Step 8: After sealing the base with epoxy resin, the product is considered a finished product once it passes the test.

[0025] At high temperatures, the glass powder in the electronic paste is in a liquid state and can penetrate into the micropores of the ceramic, thus playing an adhesive role. The molybdenum and manganese in the electronic paste act as conductors during nickel electroplating and can be bonded to Kovar alloy electrodes in subsequent brazing.

[0026] Specifically, step one employs a sintering temperature of 1150–1300℃ to form a uniform and dense microstructure in the alumina matrix. This retains adequate porosity channels for subsequent metal infiltration while avoiding excessive density that could hinder infiltration. This parameter forms a gradient with the subsequent sintering temperature of the copper ring 12, ensuring good atomic diffusion conditions at the interface between the ceramic matrix and the copper layer, providing structural support for a high bonding rate.

[0027] Step two involves stamping 200-300 micrometers of oxygen-free copper foil. This thickness ensures that the copper ring 12 has sufficient metal to participate in the infiltration reaction while avoiding thermal expansion mismatch caused by excessive thickness. Step three, the pre-oxidation treatment, forms a copper oxide film on the surface of the copper ring 12. Copper oxide, as a reaction intermediate, can lower the interfacial reaction barrier between copper and aluminum oxide, promoting Cu at high temperatures. + Al 3+ The mutual diffusion significantly enhances the penetration depth and reaction sufficiency of metals and ceramics.

[0028] Step five controls the eutectic temperature to 1066–1083℃, coupled with an oxygen content environment of 0.2%–0.8%. This ensures a sufficient eutectic reaction between the copper ring 12 and the ceramic matrix, while avoiding excessive oxidation of copper due to excessively high oxygen content or incomplete reaction due to excessively low oxygen content. Under these process conditions, copper and alumina deeply penetrate to form Cu(AlO2)2 and CuAlO2 composite oxides, creating an integrated structure of the ceramic matrix, composite oxide transition layer, and copper ring 12. The transition layer has a uniform thickness and tight bonding, increasing the interfacial bonding rate by more than 30% and reducing gaps and delamination risks.

[0029] Step four involves precisely assembling the copper ring 12 into the countersunk hole 11, followed by fusion sintering to maximize the contact area between the copper ring 12 and the ceramic substrate, avoiding insufficient local penetration caused by assembly misalignment. Step six involves brazing the metal electrode 15 and the copper ring 12 with silver-copper solder 17. The silver-copper solder 17 has excellent wetting properties and can further penetrate along the micro-gap at the interface between the copper ring 12 and the ceramic, filling the micro-pores. At the same time, it forms a strong metallurgical bond with the pre-oxidized copper ring 12, further improving the overall bonding rate of the metal electrode 15, the copper ring 12, and the ceramic substrate, ensuring conductivity and structural stability.

[0030] The Cu(AlO2)2 and CuAlO2 composite oxides generated during the fusion sintering process exhibit excellent lattice matching with both alumina ceramics and copper, effectively mitigating the difference in thermal expansion coefficients between ceramics and metals and reducing interfacial stress. Simultaneously, the composite oxides, acting as a transition phase, organically link the ionic bonds of the ceramics with the metallic bonds of the metal, increasing the interfacial penetration depth from tens of micrometers in conventional processes to the hundreds of micrometers level. This results in a bonding strength increase of over 40% compared to traditional processes, ensuring that the product will not experience interfacial delamination due to vibration or temperature cycling during long-term use.

[0031] In step one, sintering aids such as CuO, Nb2O5, TiO2, and Na2O / K2O are added to lower the sintering temperature.

[0032] In summary, the present invention possesses the excellent characteristics described above, which enhances its effectiveness in use compared to previous technologies, making it a highly practical product.

[0033] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A ceramic-metallized silicon photovoltaic cell, characterized in that, The substrate includes a base formed by sintering alumina ceramic and metallic copper. The top of the substrate has a countersunk hole, and a copper ring formed by stamping oxygen-free copper foil is installed in the countersunk hole. A copper oxide thin film layer is formed on the surface of the copper ring. The substrate has a chip slot, and a control chip is installed in the chip slot. Metal electrodes are brazed to the copper ring, and the inner end of the metal electrodes is inserted into the chip slot and connected to the control chip for signal transmission.

2. The ceramic-metallized silicon photovoltaic cell according to claim 1, characterized in that: A metal wire is installed at the inner end of the metal electrode, and the other end of the metal wire is electrically connected to the control chip.

3. A ceramic-metallized silicon photovoltaic cell according to claim 2, characterized in that: The depth of the countersink is 200-300 micrometers.

4. A ceramic-metallized silicon photovoltaic cell according to claim 1, characterized in that: The thickness of the copper metal is 10-20 micrometers.

5. A method for processing a ceramic-metallized silicon photovoltaic cell, wherein the ceramic-metallized silicon photovoltaic cell according to any one of claims 1-4 is characterized in that: It includes the following steps; Step 1: Alumina dry powder is pressed into a matrix shape, and then sintered at 1150-1300℃ for 2-4 hours to form a matrix base; Step 2: Select oxygen-free copper foil with a thickness of 200-300 micrometers and stamp it into a matching copper ring according to the size of the metal electrode; Step 3: Pre-oxidize the copper ring and the substrate separately, and a thin film of copper oxide will be formed on the surface of the copper ring; Step 4: Assemble the copper ring and the base. Assemble the copper ring into the base where countersunk holes for the metal electrodes need to be made. Step 5: The copper ring and the base are fused and sintered at a temperature of 1066-1083℃ and an oxygen content of 0.2%-0.8%, so that the copper and alumina ceramic undergo a eutectic reaction and produce Cu(AlO2)2 and Cu(AlO2) composite oxides. Step 6: Insert the metal electrode into the pre-drilled hole on the substrate base, and braze the metal electrode to the copper ring together with the help of silver-copper solder to form the base of the silicon photovoltaic cell; Step 7: Attach the control chip to the base and use gold wire to bond the PN terminals of the control chip to the two metal electrodes of the base. Step 8: After sealing the base with epoxy resin, the product is considered a finished product once it passes the test.

6. The method for processing a ceramic-metallized silicon photovoltaic cell according to claim 5, characterized in that: In step one, CuO, Nb2O5, TiO2, and Na2O / K2O are added as sintering aids to lower the sintering temperature.

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