A copper clamp for parallel connection of high-power silicon carbide chips

Abstract

This invention relates to a copper clip for parallel connection of high-power silicon carbide chips, used to achieve parallel interconnection of multiple silicon carbide chips. The copper clip includes a clip body and a chip bonding section. The clip body adopts a large-area, one-piece molded structure, and its area can cover the top of multiple silicon carbide chips to form a continuous current transmission channel. This copper clip has an ingenious structure. By setting the clip body and chip bonding section, and by adopting a large-area, one-piece molded structure, the clip body can cover the top of multiple silicon carbide chips to form a continuous current transmission channel. In other words, by integrating the copper clip into a large area, it can meet the high current carrying requirements of multiple chips in parallel connection, ensuring the service life of the copper clip while improving the user experience. This is conducive to the promotion and application of the aforementioned copper clip for parallel connection of high-power silicon carbide chips in the field of power semiconductor packaging technology.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor packaging technology, and more specifically to a copper clip for parallel connection of high-power silicon carbide chips. Background Technology

[0002] With the upgrade of new energy vehicles to 800V high-voltage platforms and the increase in power density of photovoltaic inverters and energy storage systems, silicon carbide power modules are gradually becoming core components in high-voltage, high-power scenarios. To meet the requirements of 300kW-level power output and continuous DC drain current of over 600A, multi-chip parallel technology has become a key means to improve the current carrying capacity of modules.

[0003] Copper clips are a key component in high-power silicon carbide power modules, used to replace traditional aluminum wire bonding for high-performance electrical connections between chips and external circuits. As a core component in multi-chip parallel interconnection, the design of copper clips directly affects the module's current transmission efficiency, heat dissipation performance, structural reliability, and signal control compatibility. Traditional copper clips typically employ a split design, leading to uneven current transmission paths between chips and difficulty in meeting the high current carrying capacity requirements of multi-chip parallel connections. This results in problems such as concentrated localized heat generation and difficulty meeting the demands of high-voltage platforms, easily causing damage to the copper clips and affecting their lifespan, thus hindering the market promotion and application of traditional copper clips. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a copper clip for parallel connection of high-power silicon carbide chips. This copper clip has an ingenious structure. By integrating the copper clip into a large area, it can meet the high current carrying requirements of multiple chips in parallel connection, ensuring the service life of the copper clip while improving the user experience. This is conducive to the promotion and application of the copper clip for parallel connection of high-power silicon carbide chips in the field of power semiconductor packaging technology.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a copper clip for parallel connection of high-power silicon carbide chips, used to realize the parallel interconnection of multiple silicon carbide chips; the copper clip includes a clip body and a chip welding part, the clip body adopts a large-area integral molding structure and the area of ​​the clip body can cover the top of multiple silicon carbide chips to form a continuous current transmission channel.

[0006] As a preferred embodiment of the present invention, a hollow region of a predetermined height is formed between the clip body and the chip welding part to provide sufficient operating space for aluminum wire bonding.

[0007] As a preferred embodiment of the present invention, the height of the hollow region is ≥0.8mm.

[0008] As a preferred embodiment of the present invention, the clip body is provided with a plurality of holes for the plastic sealant to pass through, the area of ​​a single hole is 2 to 5 mm2, and the total area of ​​the plurality of holes accounts for 15% to 25% of the area of ​​the clip body.

[0009] As a preferred embodiment of the present invention, a guide plate is formed inside the hole.

[0010] As a preferred embodiment of the present invention, a compaction plate is formed at the bottom of the flow guide plate, which can be pressed onto the top of the silicon carbide chip, and the flow guide plate, the compaction plate and the clip body are integrally formed.

[0011] As a preferred embodiment of the present invention, the shape of the hole is circular, square, or elliptical.

[0012] As a preferred embodiment of the present invention, the number of silicon carbide chips is 8.

[0013] As a preferred embodiment of the present invention, the copper clip is made of oxygen-free copper.

[0014] In a preferred embodiment of the present invention, the thickness of the copper clip is 0.3 mm.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The copper clip of the present invention for parallel connection of high-power silicon carbide chips has an ingenious structure. By setting the clip body and the chip welding part, the clip body adopts a large-area integral molding structure, and the area of ​​the clip body can cover the top of multiple silicon carbide chips to form a continuous current transmission channel. That is, by designing the copper clip as an integral large area, it can meet the high current carrying requirements of multiple chips in parallel connection, ensuring the service life of the copper clip while improving the user experience. This is conducive to the promotion and application of the above-mentioned copper clip for parallel connection of high-power silicon carbide chips in the field of power semiconductor packaging technology. Attached Figure Description

[0016] Figure 1 This is a front view of the structure of a copper clip for parallel connection of high-power silicon carbide chips in an embodiment;

[0017] Figure 2 This is a side view of the structure of a copper clip for parallel connection of high-power silicon carbide chips in the embodiment;

[0018] Figure 3 This is a schematic diagram of the structure of a copper clip used for parallel connection of high-power silicon carbide chips in one embodiment.

[0019] Reference numerals: 1. Clip body; 2. Chip welding section; 3. Hollow area; 4. Hole; 5. Guide plate; 6. Compactor plate. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0021] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0023] Traditional copper clips typically employ a split design, resulting in uneven current transmission paths between chips. They also struggle to meet the high current carrying capacity requirements of multiple chips connected in parallel, leading to issues such as concentrated localized heat generation. Furthermore, they are ill-suited for high-voltage platform requirements, easily causing damage to the copper clips and impacting their lifespan. This hinders the promotion and application of traditional copper clips in the market.

[0024] Example: To solve the above-mentioned technical problems, such as Figures 1 to 3 As shown in this embodiment, a copper clip for parallel connection of high-power silicon carbide chips is primarily designed to achieve efficient parallel interconnection of multiple silicon carbide chips, while simultaneously meeting requirements for signal control connections, uniform molding compound filling, low stress reliability, and low stray inductance. It is suitable for 300kW-level power output scenarios on 800V high-voltage platforms, thereby improving the overall performance and lifespan of the silicon carbide module. Specifically, the copper clip mainly consists of a clip body 1 and chip soldering parts 2. The clip body 1 adopts a large-area, one-piece molded structure, and its area can cover the top of multiple silicon carbide chips to form a continuous current transmission channel. The chip soldering parts 2 are used to connect to the top of the chips. In this embodiment, there are multiple chip soldering parts 2, which are equidistantly arranged along the edge of the clip body 1 to ensure the stability of the copper clip during use and reduce the probability of detachment or poor contact.

[0025] In this embodiment, the clip body 1 adopts a large-area integrated molding structure instead of the traditional segmented or split design, which can effectively eliminate current path breaks. It also connects multiple silicon carbide chips at the same time to achieve parallel current sharing, ensuring that the 600A+ high current is evenly distributed and avoiding local heat concentration.

[0026] In this embodiment, a hollow region 3 with a preset height is formed between the clamp body 1 and the chip bonding part 2, providing sufficient operating space for aluminum wire bonding. Specifically, a specific vertical distance is formed between the clamp body 1 and the chip bonding part 2 to meet the vertical insertion angle of the aluminum wire bonding equipment. Compared to traditional copper clamps that are tightly attached to the chip, the three-dimensional operating space reserved in the copper clamp of this embodiment, i.e., the hollow region 3, allows the bonding equipment to move freely, reducing installation difficulty. In this embodiment, the height of the hollow region 3 is ≥0.8mm. This hollow region 3 provides sufficient operating space for aluminum wire bonding, enabling aluminum wire connections between the chip gate, source, and other signal terminals and the internal signal terminals of the module without affecting the construction of signal control paths. It is also compatible with multiple bonding processes and reserves upgrade potential.

[0027] To ensure the molding compound reaches the area below the top of the chip and to fully fill the inter-chip region, this embodiment includes holes 4 on the clip body 1 for the molding compound to pass through. These holes 4 are through-holes, forming a vertical filling channel to guarantee effective filling. Multiple holes 4 are equidistantly distributed on the clip body 1. This multi-point distribution of holes 4 effectively shortens the flow path of the molding compound, improving molding efficiency. Furthermore, the holes 4 serve as venting channels, allowing gas in the molding compound to escape smoothly, thus ensuring the reliability of the insulation layer thickness formed by the molding compound and reducing weak points in the insulation and the formation of thermally resistive layers. To balance the filling efficiency of the molding compound with the structural strength of the copper clip body, the area of ​​a single hole 4 in this embodiment is 2–5 mm². 2 This area ensures the fluidity of the molding compound, preventing pore blockage and excessively high local current density, thus avoiding concentrated heat generation. In this embodiment, the total area of ​​the plurality of holes 4 accounts for 15% to 25% of the area of ​​the clip body 1, ensuring sufficient molding compound flow while maintaining the mechanical strength of the clip body 1. If the total area of ​​the plurality of holes 4 is less than 15% of the area of ​​the clip body 1, it will result in insufficient molding compound flow and inadequate filling; if the total area of ​​the plurality of holes 4 is greater than 25% of the area of ​​the clip body 1, it will lead to a decrease in the mechanical strength of the clip body 1 and a reduction in its current carrying capacity.

[0028] In this embodiment, a flow guide plate 5 is formed within the aforementioned hole 4. The top of the flow guide plate 5 is integrally formed with the clip body 1, and the bottom of the flow guide plate 5 points towards the chip gap. The two flow guide plates 5 form a funnel shape, guiding the molding compound to the chip gap in a directional manner to ensure the encapsulation effect. In this embodiment, a compaction plate 6 is also formed at the bottom of the flow guide plate 5, which can press against the top of the silicon carbide chip. The compaction plate 6 provides continuous mechanical pressure to ensure that the top of the chip is tightly attached to the welding part 2, and can compensate for the chip height tolerance (±20μm), adapting to the slight height difference of eight chips and avoiding chip cracking caused by excessive pressure at a single point. In this embodiment, the flow guide plate 5, the compaction plate 6, and the clip body 1 are all integrally formed from oxygen-free copper material, without welding or sintering layers throughout the process, to ensure continuous heat conduction efficiency and constant resistivity. At the same time, the integral forming can also effectively ensure the overall structural stability of the copper clip and improve its reliability during use.

[0029] In this embodiment, the shape of the aforementioned hole 4 is circular, square, or elliptical. Its main purpose is to ensure that the high Tg / CTI epoxy resin molding compound can flow smoothly to the bottom of the clip body 1, filling all gaps below the clip body 1, around the chip, and on the substrate surface. This avoids problems such as molding compound filling the hole 4 and poor backflow, improving the module's insulation performance and structural integrity. Simulation verification (such as fluid dynamics simulation) shows that this hole 4 layout can achieve a molding compound filling rate of over 99%, completely solving the molding defects of traditional clip structures. The shape of the aforementioned hole 4 is not limited.

[0030] To meet the requirements of 300kW power output and continuous DC drain current of over 600A, this embodiment uses eight silicon carbide chips, 8×75A=600A, which just meets the requirements of the 300kW / 800V platform. Due to the current capability limitation of a single chip, six chips would not provide sufficient current margin, and ten chips would be too difficult to package. Therefore, eight chips are the minimum necessary number to meet the technical specifications and represent the optimal balance between performance, reliability, and cost.

[0031] The copper clip in this embodiment is made of oxygen-free copper, which has high conductivity (≥58MS / m), high thermal conductivity (≥390W / (m·K)) and excellent processing and forming performance. The thickness of the copper clip is set to 0.3mm, which takes into account both structural strength and current transmission efficiency, and can meet the high current carrying requirements of eight chips connected in parallel.

[0032] In this embodiment, the chip welding section 2, i.e., the welding position between the copper clip and each chip, can adopt a bifurcated structure. That is, the contact area corresponding to each chip is divided into 2 to 4 independent contact branches. Each branch has a raised bump at its end, with a bump height of 0.1 to 0.2 mm and an arc-shaped contact surface at the top (radius of curvature 0.3 to 0.5 mm). The advantages of this design are: the bifurcated structure disperses the welding stress, avoids concentrated pressure on the chip surface from a single contact surface, buffers the thermal stress caused by the difference in thermal expansion coefficients between the copper clip and the chip and substrate, reduces stress concentration at the solder joint during thermal cycling, reduces the risk of solder joint cracking, and the raised bump makes the contact area during welding more precise, ensuring uniform distribution of solder (such as pre-formed solder pads) and improving welding reliability.

[0033] This embodiment presents a copper clip for parallel connection of high-power silicon carbide chips. The copper clip has an ingenious structure, which is composed of a clip body 1 and a chip welding part 2. The clip body 1 adopts a large-area integral molding structure, and the area of ​​the clip body 1 can cover the top of multiple silicon carbide chips to form a continuous current transmission channel. That is, by integrating the copper clip into a large area, it can meet the high current carrying requirements of multiple chips in parallel connection, ensuring the service life of the copper clip while improving the user experience. This is conducive to the promotion and application of the copper clip for parallel connection of high-power silicon carbide chips in the field of power semiconductor packaging technology.

[0034] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention; therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0035] Although this document frequently uses reference numerals in the figures, such as 1. clip body; 2. chip soldering part; 3. hollow area; 4. hole; 5. guide plate; 6. compaction plate, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A copper clip for parallel connection of high-power silicon carbide chips, characterized in that: Used to realize the parallel interconnection of multiple silicon carbide chips; the copper clip includes a clip body (1) and a chip welding part (2). The clip body (1) adopts a large-area integral molding structure and the area of ​​the clip body (1) can cover the top of multiple silicon carbide chips to form a continuous current transmission channel.

2. The copper clip for parallel connection of high-power silicon carbide chips according to claim 1, characterized in that: A hollow area (3) with a preset height is formed between the clip body (1) and the chip welding part (2) to provide sufficient operating space for aluminum wire bonding.

3. A copper clip for parallel connection of high-power silicon carbide chips according to claim 2, characterized in that: The height of the hollow region (3) is ≥0.8mm.

4. A copper clip for parallel connection of high-power silicon carbide chips according to claim 2, characterized in that: The clamp body (1) has multiple holes (4) for the molding compound to pass through, and the area of ​​each hole (4) is 2-5 mm. 2 Furthermore, the total area of ​​the plurality of holes (4) accounts for 15% to 25% of the area of ​​the clip body (1).

5. A copper clip for parallel connection of high-power silicon carbide chips according to claim 4, characterized in that: A guide plate (5) is formed inside the hole (4).

6. A copper clip for parallel connection of high-power silicon carbide chips according to claim 5, characterized in that: The bottom of the flow guide plate (5) has a compaction plate (6) that can be pressed onto the top of the silicon carbide chip. The flow guide plate (5), the compaction plate (6) and the clip body (1) are integrally formed.

7. A copper clip for parallel connection of high-power silicon carbide chips according to claim 4, characterized in that: The hole (4) is round, square or elliptical in shape.

8. A copper clip for parallel connection of high-power silicon carbide chips according to claim 1, characterized in that: There are eight silicon carbide chips.

9. A copper clip for parallel connection of high-power silicon carbide chips according to claim 1, characterized in that: The copper clip is made of oxygen-free copper.

10. A copper clip for parallel connection of high-power silicon carbide chips according to claim 9, characterized in that: The thickness of the copper clip is 0.3 mm.

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