Bypass diode for improving welding application of electric resistance welding

Abstract

A bypass diode for improving welding application of electric resistance welding is characterized in that the bypass diode is structurally connected with a chip through first solder paste, connected with the chip and a copper connecting piece in parallel through second solder paste and connected with the copper connecting piece through third solder paste from right to left, and the above structures are wrapped by a plastic package body; the third solder paste and the copper connecting piece are connected with the first copper frame, the second copper frame is arranged on the right side of the first solder paste, and the two copper frames are provided with a tin block boss, an electric resistance welding boss, an electric resistance welding groove, a tin block boss groove and a via hole. The bottom of the chip is connected with the second copper frame.

Description

A bypass diode for improving resistance welding applications Technical Field

[0001] This utility model discloses a bypass diode for improving resistance welding applications, belonging to the field of diode manufacturing. Background Technology

[0002] As a connector for solar cell modules, the main function of a photovoltaic junction box is to conduct the electrical energy generated by the solar cell module through cables. Due to the special application scenarios of solar cells and their high cost, photovoltaic junction boxes must be specially designed to meet the usage requirements of solar cell modules.

[0003] Photovoltaic junction boxes primarily serve two functions: their basic function is to connect photovoltaic modules to the load, drawing out the current generated by the modules and producing power. An additional function is to protect the module leads and prevent hot spot effects.

[0004] The bypass diode is connected in parallel across the battery string (usually 18-24 batteries per group). When a group of batteries is blocked, the diode conducts, providing a low-impedance bypass path for the current, bypassing the failure area and avoiding concentrated heat generation from reverse current.

[0005] As the power output of solar modules continues to increase, the conversion efficiency of solar cells is also improving year by year, leading to a significant increase in the operating current within photovoltaic systems. Junction boxes, as crucial connection and protection devices between solar modules, are responsible for both the power output of the photovoltaic modules and the protection of the circuits; therefore, they need to possess higher current-carrying capacity.

[0006] In photovoltaic junction boxes, bypass diodes are electrically connected and mechanically fixed by resistance welding (resistance spot welding / resistance brazing). The rational design of the welding process directly affects the reliability of the diodes, heat dissipation performance, and long-term stability of the module.

[0007] Resistance welding melts the metal interface at localized high temperatures, forming a metallurgical bond that ensures minimal contact resistance (typically <0.5mΩ) between the diode leads and the copper conductor, reducing conduction losses. The welding surface must cover the diode's rated current (e.g., 10A or higher) to prevent localized overheating due to poor contact. The welding joint must withstand a pull-out force of ≥50N to prevent loosening due to vibration during transportation or installation. The PAD area of ​​a diode refers to the metal pad area within an integrated circuit (IC) used for external connections. The PAD area is typically located at the edge of the chip and is used for electrical connections to external circuits. The PAD area is the interface between the diode and external circuits, achieving electrical connection through metal pads. It allows external signals or power to be connected to the diode's internal structure via wire bonding or flip-chip technology.

[0008] The shortcomings of existing technology are that, under the existing shape and structure, when using resistance welding cables, the resistance welding electrode directly contacts the copper frame, which leads to stress transfer and affects the reliability of the device. In addition, the welding area is close to the PAD area, which makes it easy for heat transfer to occur, causing the solder in the PAD area to melt and resulting in failure at the application end.

[0009] In the existing bypass diode structure, when using resistance welding of copper current conductors, the resistance welding electrode directly contacts the copper frame, which can lead to stress transfer and affect device reliability. In addition, the resistance welding is close to the solder block welding area, which can easily cause heat transfer, resulting in the solder in the solder block welding area melting, the solder block falling off, and failure at the application end. Summary of the Invention

[0010] The purpose of this invention is to propose a bypass diode for improving resistance welding applications.

[0011] The technical solution of this utility model is a bypass diode for improving resistance welding applications. The bypass diode structure, from right to left, consists of a first solder paste 1 connecting a chip 2, a second solder paste 3 connecting the chip 2 and a copper connecting piece 4, a third solder paste 5 connecting the copper connecting piece 4, and a molding compound 12 encapsulating the above structure. The third solder paste 5 and the copper connecting piece 4 connect to a first copper frame 6 (on the left). A second copper frame is located to the right of the first solder paste 1. The two copper frames 6 are provided with solder block bosses 7, resistance welding bosses 8, resistance welding grooves 9, solder block boss grooves 10, and vias 11. The resistance welding bosses 8 and the solder block bosses are respectively the solder block welding area and the resistance welding boss area.

[0012] While keeping the overall size of the Schottky diode unchanged, the solder pad area is reduced, and two resistance welding bosses are added at both ends, increasing the distance between the solder pad area and the resistance welding boss area. The position of the resistance welding bosses is fixed within the resistance welding area.

[0013] The copper frame 6 is provided with a structural tin block boss 7, a resistance welding boss 8, a resistance welding groove 9, a tin block boss groove 10, and a through hole 11. The bottom of the chip 2 is connected to the second copper frame 6; the tin block boss 7 corresponds to the boss groove 10, and the resistance welding boss 8 corresponds to the resistance welding groove 9.

[0014] Beneficial effects: Adding two resistance welding bosses at both ends of the copper frame, with corresponding grooves on the opposite side of the bosses, concentrates the stress during the resistance welding process in the resistance welding boss area and prevents it from spreading to other areas, reducing the stress impact on the chip; the targeted resistance welding electrode design increases the effective area of ​​resistance welding by adjusting the position of the resistance welding bosses, improving welding quality and reducing contact resistance; by reducing the size of the solder block welding area and increasing the distance between it and the resistance welding boss, the temperature of the solder block welding area during resistance welding is reduced, improving the reliability of the device in overall application. Attached Figure Description

[0015] Figure 1 is a structural schematic diagram of this utility model;

[0016] Figure 2 is a front view of Figure 1;

[0017] Explanation of the labels in the diagram:

[0018] 1. First solder paste; 2. Chip; 3. Second solder paste; 4. Copper connector; 5. Third solder paste; 6. Copper frame;

[0019] 7. Solder block boss; 8. Solder resist boss; 9. Resistance soldering groove; 10. Solder block boss groove; 11. Via; 12. Molded body. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] The bypass diode structure, from right to left, is connected to one end of chip 2 via first solder paste 1, second solder paste 3 connected to the second end of chip 2 and copper connecting piece 4, third solder paste 5 also connected to copper connecting piece 4, and encapsulated by molding compound 12. The third solder paste 5 and copper connecting piece 4 are connected to the first copper frame 6 (on the left). A second copper frame is provided on the right side of the first solder paste 1. The two copper frames 6 are provided with solder block bosses 7, resistance welding bosses 8, resistance welding grooves 9, solder block boss grooves 10, and vias 11.

[0022] Example: GF4045TS-1 type, as shown in Figures 1 and 2, this utility model includes a copper frame 6 on both sides of the chip, a chip 2, a copper connecting piece 4, a first solder paste 1, a second solder paste 3, and a third solder paste 5. It is assembled according to Figure 1 using appropriate automated equipment. The copper frame 6 is connected to the chip 2 via the first solder paste 1, the copper connecting piece is connected to the chip 2 via the second solder paste 3, and the copper connecting piece is connected to the first copper frame 6 via the third solder paste 5. After assembly, it is soldered in a nitrogen soldering furnace. The solder paste can be high-temperature lead-tin solder with a melting temperature of approximately 310 degrees Celsius. After soldering, a molding compound 12 is added using a molding die. The second copper frame 6 is located on the right side and has structural solder block bosses 7, resistance welding bosses 8, resistance welding grooves 9, solder block boss grooves 10, and vias 11. Figure 2 shows a front view of this utility model.

[0023] Two resistance welding bosses are added at both ends. The welding bosses are 6-9mm long, 1.5-3mm wide, and 0.1mm deep. By reducing the width of the solder reservoir, the distance between the solder block welding area and the resistance welding area is increased, preventing the residual heat of the resistance welding from melting the solder block. The position of the resistance welding bosses is fixed in the resistance welding area.

[0024] The chip (2) is a Schottky chip or a higher voltage diode chip, etc.

[0025] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A bypass diode for improving resistance welding applications, characterized in that, The bypass diode has a structure from right to left consisting of a first solder paste connecting the chip, a second solder paste connecting the chip and a copper connector, a third solder paste connecting the copper connector, and a plastic encapsulation covering the above structure. The third solder paste and the copper connector connect to the first copper frame. A second copper frame is provided to the right of the first solder paste. The two copper frames are provided with solder block bosses, resistance welding bosses, resistance welding grooves, solder block boss grooves, and vias.

2. A bypass diode to improve resistance welding applications according to claim 1, characterized in that: The bottom of the chip is connected to a second copper frame.

3. A bypass diode to improve resistance welding applications according to claim 1, characterized in that The solder block boss corresponds to the boss groove, and the resistance welding boss corresponds to the resistance welding groove.

4. A bypass diode to improve resistance welding applications according to claim 1, characterized in that: The dimensions of the two resistance welding bosses at both ends are as follows: the welding boss is 6-9mm long, 1.5-3mm wide, and 0.1mm deep.

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