Copper sheet pre-welding structure of mesa process thyristor chip

Abstract

The utility model aims to solve the problems that the cost is high and a thyristor is easy to clamp when a molybdenum sheet is positioned due to the fact that the molybdenum sheet is used as welding transition in the existing thyristor structure. The utility model provides a copper sheet pre-welding structure of a mesa process thyristor chip, which comprises a thyristor and a pre-welding piece, one side of the thyristor is connected with the pre-welding piece, and the other side of the thyristor is connected with an external component; the pre-welding piece comprises a base and a boss, the boss is located on the side, close to the thyristor, of the base, and the upper surface of the boss is connected with the thyristor in an attached mode. The creepage distance between the thyristor electrode and the base is increased, arcing between the thyristor electrode and the base is avoided, a molybdenum sheet can be avoided, and the cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of thyristor technology, and in particular to a copper sheet pre-welded structure for a mesa-process thyristor chip. Background Technology

[0002] Two main manufacturing processes are used for thyristors in power semiconductor devices both domestically and internationally: mesa thyristors and planar thyristors. Each process has its advantages and disadvantages. Mesa thyristors are generally more suitable for high-voltage devices, while planar thyristors are better suited for medium- and low-voltage devices. When using mesa thyristors, voltage divider rings are generally not used; however, when using planar thyristors, voltage divider rings are unavoidable when the voltage exceeds 600V, which wastes some chip area. Mesa thyristors require processes such as trench lithography and trench filling. The PN junction breakdown in mesa thyristors is straight, with a very high breakdown voltage, resulting in higher reliability. Therefore, mesa thyristors are more commonly used in high-voltage, high-current applications in industrial settings.

[0003] However, due to the unique chip structure of mesa-process thyristors, there are some challenges in the packaging and manufacturing process. These mainly manifest as insufficient creepage distance, leading to arcing and failure; and high current-rated chips experiencing significant structural stress after soldering, resulting in degraded electrical performance. Existing solutions involve soldering a rare metal molybdenum sheet (approximately 0.5mm thick) beneath the thyristor. This increases the creepage distance between the thyristor mesa and the ceramic copper-clad laminate, reducing voltage arcing failure and alleviating welding structural stress, as illustrated in patent CN219832644U. The welding structural stress is primarily caused by the difference in thermal expansion coefficients between different materials. The thermal expansion coefficient of silicon in conventional thyristors is much lower than that of copper, a common conductor. Therefore, molybdenum, with its coefficient of thermal expansion falling between the two, can act as a stress buffer. However, due to the high material and manufacturing costs of molybdenum sheets, in order to reduce costs, the size of the molybdenum sheets is usually designed to be smaller than the welding surface of the thyristor. This also means that during the packaging process, the thyristor welding positioning fixture usually directly contacts and acts on the periphery of the thyristor chip. During the assembly process of the thyristor chip with the positioning fixture, it is inevitable that they will bump and come into contact, which can easily cause damage, leading to chip voltage failure and affecting the normal operation of the thyristor. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies and provide a copper sheet pre-soldering structure for mesa-process thyristor chips.

[0005] To solve the above problems, the present invention adopts the following solution:

[0006] A pre-welding structure of a copper sheet for a mesa process thyristor chip, including a thyristor and a pre-welding component; one side of the thyristor is connected to the pre-welding component, and the other side of the thyristor is connected to external components; the pre-welding component includes a base and a boss, the boss is located on the side of the base close to the thyristor, and the upper surface of the boss is in contact connection with the thyristor.

[0007] Further, the shape of the base corresponds to the shape of the contact surface of the thyristor close to the base; the edge shape and size of the base are larger than the contact surface of the thyristor; the distance between the edge of the base and the edge of the contact surface of the thyristor is 1 mm to 2 mm.

[0008] Further, the edge size of the boss corresponds to the shape of the contact surface of the thyristor; the edge shape and size of the boss are smaller than the contact surface of the thyristor; the distance between the edge of the boss and the edge of the contact surface of the thyristor is 0.4 mm to 1 mm.

[0009] Further, the thickness of the base is 0.5 mm to 0.7 mm.

[0010] Further, the thickness of the boss is 0.3 mm to 0.5 mm.

[0011] Further, the boss includes several partitions, and gap channels for exhausting gas and releasing stress are provided between the corresponding partitions.

[0012] Further, the partitions are in a "field" shape or several circles.

[0013] Further, the boss is formed by stamping, and the boss and the base are integrally formed.

[0014] Further, the pre-welding component is made of pure copper material or copper-based composite material as a whole; the copper-based composite materials include Cu-Mo, Cu-W, and Cu / 36Ni-Fe / Cu.

[0015] The beneficial effects of the present utility model are as follows:

[0016] By setting the combination form of the base and the boss, the creepage distance between the thyristor electrode and the base is increased, avoiding arcing and short circuit between the two, and ensuring the stable operation of the thyristor without using molybdenum sheets;

[0017] By setting the shape of the base to be larger than the shape of the contact surface of the thyristor, it effectively avoids the external tooling fixture from clamping the thyristor during welding positioning, resulting in damage to the thyristor;

[0018] By setting the shape of the boss to be smaller than the shape of the contact surface of the thyristor, a gap is formed between the thyristor and the base, increasing the creepage distance;

[0019] By setting up bosses including several partitions and gap channels, the gas generated during welding is released on the one hand, reducing the bubble generation rate, and the structural stress is released on the other hand, making the connection between the thyristor and the bosses more stable.

[0020] By using copper or copper-based composite materials for the bosses, production costs are reduced, and the overcurrent and heat dissipation capabilities of the thyristor module are improved, thereby increasing the overall power density of the module. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of Example 1;

[0022] Figure 2 This is an exploded view of the overall structure of Example 1.

[0023] Figure labeling: 1. Thyristor; 2. Pre-welded component; 21. Base; 22. Boss; 23. Partition; 24. Gap channel. Detailed Implementation

[0024] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the figures only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] Example 1:

[0027] like Figure 1 and Figure 2As shown in the figure, a pre-welding structure of a copper sheet for a mesa process thyristor chip includes a thyristor 1 and a pre-welding component 2. One side of the thyristor 1 is connected to the pre-welding component 2, and the other side of the thyristor 1 is connected to external components. The pre-welding component 2 includes a base 21 and a boss 22. The boss 22 is located on one side of the base 21 close to the thyristor 1, and the upper surface of the boss 22 is in contact connection with the thyristor 1. By adding the boss 22 on the base 21, the creepage distance between the electrode of the thyristor 1 and the base 21 is increased, avoiding the failure of the thyristor 1 caused by voltage arcing. In addition, the fixture can directly clamp the base 21, avoiding knocking damage to the thyristor 1.

[0028] The shape of the base 21 corresponds to the shape of the bonding surface of the thyristor 1 close to the base 21, where the bonding surface is the surface where the thyristor 1 is in contact and conducts with the boss 22. The distance between the edge of the base 21 and the edge of the bonding surface of the thyristor 1 is 1 mm to 2 mm, making the edge shape size of the base 21 larger than the size of the bonding surface of the thyristor 1, effectively avoiding directly clamping the thyristor 1 during fixture clamping and positioning, resulting in damage and affecting the performance of the thyristor 1.

[0029] The edge size of the boss 22 corresponds to the shape of the bonding surface of the thyristor 1. The edge shape of the boss 22 is smaller than the area of the bonding surface of the thyristor 1. The distance between the edge of the boss 22 and the edge of the bonding surface of the thyristor 1 is 0.4 mm to 1 mm. In this way, a gap can be formed between the thyristor 1 and the base 21, increasing the creepage distance.

[0030] The thickness of the base 21 is 0.5 mm to 0.7 mm, and the thickness of the boss 22 is 0.3 mm to 0.5 mm.

[0031] The boss 22 includes several partitions 23, and gap channels 24 for exhausting gas and releasing stress are provided between the corresponding partitions 23. Through the gap channels 24, it is convenient to discharge the fumes generated during welding, reducing the possibility of pores generated inside the welding part, improving the electrical conductivity between the thyristor 1 and the boss 22. In addition, the gap channels 24 can also be used to release the structural stress generated by the different materials of the boss 22 and the thyristor 1 during temperature change. Specifically, the partitions 23 on the boss 22 are in the shape of a "field" character or a combination of several circles or a "cross" shaped gap channel 24 is provided on the circular boss 22. In this example, the boss 22 is formed by stamping, and the boss 22 and the base 21 are integrally made to enhance the structural strength between the boss 22 and the base 21.

[0032] The pre-welded component 2 is made entirely of copper or copper-based composite material. Copper-based composite material includes Cu-Mo, Cu-W, and Cu / 36Ni-Fe / Cu. The copper material is in direct contact with the thyristor 1. Compared with using molybdenum sheet as an indirect transition method, this reduces material costs. Furthermore, copper has better electrical and thermal conductivity than molybdenum, which improves the current carrying capacity and heat dissipation capacity of the thyristor 1 module and increases the overall power density of the module.

[0033] During implementation, by setting the combination of base 21 and boss 22, the creepage distance between the thyristor 1 electrode and base 21 is improved, avoiding arcing and short circuits between them, and ensuring stable operation of thyristor 1. By setting the shape of base 21 to be larger than the shape of the contact surface of thyristor 1, the creepage distance is effectively prevented from being clamped by external tooling fixtures during welding positioning, thus avoiding damage to thyristor 1. By setting the shape of boss 22 to be smaller than the shape of the contact surface of thyristor 1, a gap is formed between thyristor 1 and base 21, increasing the creepage distance. By setting boss 22 to include several partitions 23 and gap channels 24, the gas generated during welding is released, reducing the bubble generation rate, and structural stress is released, making the connection between thyristor 1 and boss 22 more stable. By setting boss 22 to be made of copper or copper-based composite material, the production cost is reduced, and the current carrying capacity and heat dissipation capacity of thyristor 1 module are improved, thereby increasing the overall power density of the module.

[0034] The above description is merely a specific example of this utility model and does not constitute any limitation on this utility model. Obviously, those skilled in the art, after understanding the content and principle of this utility model, may make various modifications and changes in form and details without departing from the principle and structure of this utility model. However, these modifications and changes based on the concept of this utility model are still within the protection scope of the claims of this utility model.

Claims

1. A copper pre-soldering structure for a mesa-process thyristor chip, comprising a thyristor (1), characterized in that, It further includes a pre-welded part (2); one side of the thyristor (1) is connected to the pre-welded part (2), and the other side of the thyristor (1) is connected to external components; the pre-welded part (2) includes a base (21) and a boss (22), the boss (22) is located on the side of the base (21) close to the thyristor (1), and the upper surface of the boss (22) is in close connection with the thyristor (1).

2. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 1, characterized in that, The shape of the base (21) corresponds to the shape of the mating surface of the thyristor (1) close to the base (21); the edge shape and size of the base (21) are larger than the mating surface of the thyristor (1); the distance between the edge of the base (21) and the edge of the mating surface of the thyristor (1) is 1 mm to 2 mm.

3. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 2, characterized in that, The edge size of the boss (22) corresponds to the shape of the mating surface of the thyristor (1); the edge shape and size of the boss (22) are smaller than the mating surface of the thyristor (1); the distance between the edge of the boss (22) and the edge of the mating surface of the thyristor (1) is 0.4 mm to 1 mm.

4. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 1, characterized in that, The thickness of the base (21) is 0.5 mm to 0.7 mm.

5. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 4, characterized in that, The thickness of the boss (22) is 0.3 mm to 0.5 mm.

6. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 1, characterized in that, The boss (22) includes several partitions (23), and gap channels (24) for exhausting gas and releasing stress are provided between the corresponding partitions (23).

7. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 6, characterized in that, The partitions (23) are in a "field" shape or several circles.

8. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 1, characterized in that, The boss (22) is formed by stamping, and the boss (22) and the base (21) are integrally formed.

9. The copper sheet pre-soldering structure for a mesa-process thyristor chip according to claim 8, characterized in that, The pre-welded part (2) is made of pure copper material or copper-based composite material as a whole; the copper-based composite materials include Cu-Mo, Cu-W, and Cu / 36Ni-Fe / Cu.

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