Series fast recovery epitaxial diode module and high temperature high voltage three-phase rectifier module

Abstract

The utility model discloses a series formula fast recovery epitaxial diode module and high temperature high pressure three -phase rectifier module, design the shell base of molybdenum copper material, adopt the fast recovery epitaxial diode chip of epitaxial plane technology and inner lead, vacuum welding position chip lead component in eutectic furnace of inner lead, then in hot welding platform aluminium nitride clad copper insulating plate, chip lead component and shell lead post implement welding, wherein, shell lead post is connected in two aluminium nitride clad copper insulating plate that need series, finally, the shell ceramic cover is bonded with shell and realizes series formula fast recovery epitaxial diode module. The junction temperature of diode module is improved to greater than 180 DEG C, and the reverse working voltage is greater than 1200V based on the epitaxial plane technology characteristics of the application, and the working frequency can be improved to greater than 8000HZ in combination with the platinum extension operation in epitaxial plane technology, and the assembly structure is simple, and the high temperature high pressure three -phase rectifier module realized on the basis has the advantages of simple assembly, cost controllable.

Description

Technical Field

[0001] This utility model belongs to the field of power electronics technology, specifically, it relates to a series fast recovery epitaxial diode module and a high temperature and high voltage three-phase rectifier module. Background Technology

[0002] Power electronics technology is an important component of electronic information technology and an indispensable technology for achieving informatization, intelligentization, and energy efficiency in all sectors of the world economy today.

[0003] In the field of modern high technology, all kinds of equipment are developing towards high current, high voltage, high frequency, and integration. In particular, the field of brushless motors, which are used to support these high-end equipment, is developing towards high integration.

[0004] In the field of three-phase brushless generators used in automobiles and airplanes, it is necessary to convert high-voltage AC to DC output. This requires a high-temperature, high-voltage three-phase rectifier module with a working junction temperature higher than 180℃, a reverse working voltage greater than 1200V, and a working frequency greater than 8000Hz to achieve AC to DC output.

[0005] In power electronics technology, semiconductor diodes are the most basic unit. The common design practice is to use planar rectifier diodes and assemble them into a three-phase rectifier module by pressing them together. The disadvantages are that the junction temperature can only be 125℃ and the operating frequency can only reach 2000Hz due to the limitations of the die manufacturing process of planar rectifier diodes. This cannot meet the requirements of high operating junction temperature, high reverse operating voltage and high operating frequency. In addition, the cost is high and the assembly process is complicated. Summary of the Invention

[0006] The purpose of this utility model is to provide a series fast recovery epitaxial diode module and a high-temperature and high-voltage three-phase rectifier module. First, fast recovery diode chips using epitaxial planar technology are welded and assembled into a series fast recovery epitaxial diode module. Then, three series fast recovery epitaxial diode modules are assembled with an oil tank cover plate to form a high-temperature and high-voltage three-phase rectifier module, which achieves a working junction temperature higher than 180°C, a reverse working voltage greater than 1200V, and a working frequency greater than 8000Hz.

[0007] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: A series fast recovery epitaxial diode module is proposed, comprising: The outer shell base is made by sintering a metal base plate and a metal shell together with silver-copper solder at high temperature and then precision machining. At least two aluminum nitride copper-clad insulating boards are welded to a metal base plate in a matrix structure with spacing between them; The chip lead assembly consists of multiple fast recovery epitaxial diode chips, multiple inner leads, and one inner lead post. The multiple fast recovery epitaxial diode chips are vacuum eutectic bonded to an aluminum nitride copper-clad insulating board in a matrix structure. The inner leads are transverse U-shaped structures with a width. One end of each inner lead is vacuum eutectic bonded to the fast recovery epitaxial diode chip, and the other end is vacuum eutectic bonded to the inner lead post. The housing lead post is bridging and soldered onto two aluminum nitride copper-clad insulating boards that need to be connected in series; The outer ceramic cover is bonded to the upper end of the metal shell of the outer shell base. It has holes for the inner lead post and the shell lead post to extend out. The outer periphery of the inner lead post and the shell lead post is provided with a metal platform, which is bonded to the hole.

[0008] In some embodiments of this application, the metal base plate is made of molybdenum copper; the metal shell is made of Kovar metal and is milled.

[0009] In some embodiments of this application, the inner side of the metal casing is nickel-plated, and the inner wall of its top is processed into a stepped platform structure. The stepped platform structure is nickel-removed after plating and is used to bond with the ceramic cover of the outer casing using low-temperature glass glue.

[0010] In some embodiments of this application, the outer ceramic cover uses 99.6% high-frequency black ceramic as an insulator.

[0011] In some embodiments of this application, the outer periphery of the ceramic cover is assembled with the recessed stepped platform of the metal shell, and the connection is cured in an oven at 130°C after applying low-temperature glass glue.

[0012] In some embodiments of this application, the aluminum nitride copper-clad insulating board is left blank around its perimeter, and the area outside the fast recovery epitaxial diode chip is a non-copper-clad solder resist area.

[0013] In some embodiments of this application, the housing lead post is designed as a T-shaped structure.

[0014] In some embodiments of this application, a gold-plated molybdenum sheet is vacuum eutectic welded between the fast recovery epitaxial diode chip and the aluminum nitride copper-clad insulating board.

[0015] In some embodiments of this application, a nickel-molybdenum plated sheet is vacuum eutectic welded between the fast recovery epitaxial diode chip and the inner lead.

[0016] Compared with existing technologies, the advantages and positive effects of this utility model are as follows: The series-connected fast recovery epitaxial diode module proposed in this application features a molybdenum-copper housing base, a fast recovery epitaxial diode chip using epitaxial planar technology, and internal leads. The internal leads are vacuum-welded to the chip lead assembly in a eutectic furnace. Then, the aluminum nitride copper-clad insulating plate, chip lead assembly, and housing lead posts are welded together in a hot soldering station. The housing lead posts are bridging and soldered onto two aluminum nitride copper-clad insulating plates that need to be connected in series. Finally, the ceramic cover is bonded to the housing to achieve the series-connected fast recovery epitaxial diode module. Based on the characteristics of epitaxial planar technology, this series-connected fast recovery epitaxial diode module increases the junction temperature of the diode module to greater than 180°C and the reverse working voltage to greater than 1200V. Combined with the platinum expansion operation in the epitaxial planar process, the operating frequency can be increased to greater than 8000Hz, and the assembly structure is simple.

[0017] Based on the aforementioned series-connected fast recovery epitaxial diode module, this application also proposes a high-temperature, high-voltage three-phase rectifier module, comprising: Three series-connected fast recovery epitaxial diode modules as described above; The aluminum fuel tank cover has a conical heat conductor at its bottom. Three series-connected fast recovery epitaxial diode modules are placed flat on the aluminum fuel tank cover plate according to the principle that the diode polarity is in one direction.

[0018] Compared to existing three-phase rectifier modules implemented with planar diode modules, which require accessories such as conductive plates and oil supply plates, and whose planar diodes can be damaged if the crimping process is not done properly, resulting in complex installation and high cost, this application uses a high-temperature fast recovery epitaxial diode module implemented with epitaxial planar technology. It only needs to be combined with an oil tank cover to form a three-phase high-temperature high-voltage rectifier module, which has the advantages of simple assembly, excellent performance and controllable cost.

[0019] Other features and advantages of this utility model will become clearer after reading the detailed description of the embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a side cross-sectional view of the series-connected fast recovery epitaxial diode module proposed in this application; Figure 2 This is a schematic diagram of the housing base structure of the series fast recovery epitaxial diode module proposed in this application; Figure 3 This is a schematic diagram of the aluminum nitride copper-clad insulating board assembly structure of the series fast recovery epitaxial diode module proposed in this application. Figure 4 The chip lead assembly of the series fast recovery epitaxial diode module proposed in this application is shown after vacuum welding in a eutectic furnace; Figure 5 This is a schematic diagram of the internal structure of the series fast recovery epitaxial diode module proposed in this application before it is capped. Figure 6 This is a schematic diagram of the inner lead post and housing lead post structure of the series fast recovery epitaxial diode module proposed in this application; Figure 7 This is the overall structure of the series fast recovery epitaxial diode module proposed in this application; Figure 8 This is the overall side view structure of the series fast recovery epitaxial diode module proposed in this application; Figure 9 This is the internal lead structure of the series fast recovery epitaxial diode module proposed in this application; Figure 10 This is a top view of the high-temperature and high-pressure three-phase rectifier module proposed in this application; Figure 11 This is a side view of the high-temperature and high-pressure three-phase rectifier module proposed in this application; Illustration markings: 1. Metal base plate; 2. Metal casing; 3. Aluminum nitride copper-clad insulating board; 4. Fast recovery epitaxial diode chip; 5. Inner lead; 6. Inner lead post; 7. Casing lead post; 8. Casing ceramic cover; 9. Aluminum oil tank cover; 91. Heat conductor; A. Series fast recovery epitaxial diode module; B. Stepped mesa structure; C. Mesa of casing lead post / inner lead post. Detailed Implementation

[0021] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0022] like Figure 1 As shown in the embodiment of this application, the series fast recovery epitaxial diode module consists of a housing base, an aluminum nitride copper-clad insulating plate 3, a chip lead assembly, a housing lead post 7, and a housing ceramic cover 8.

[0023] The outer casing base is formed by high-temperature sintering of a metal base plate 1 and a metal shell 2 with silver-copper solder, followed by precision machining. This outer casing base features a separate reliability design. The metal base plate 1 is made of high-quality molybdenum copper, offering excellent electrical conductivity and heat dissipation, and can withstand 20g of impact vibration. The metal shell 2 is made of 1.3mm thick Kovar metal and milled. The inner side of the metal shell 2 is nickel-plated, and its top inner wall is machined into a stepped platform structure B. This stepped platform structure B is denicked after plating to facilitate low-temperature welding with the ceramic cover 8 of the outer casing. A protruding alignment platform is located on the upper side of the metal base plate 1 corresponding to the welding position of the aluminum nitride copper-clad insulating plate 3.

[0024] A series fast recovery epitaxial diode module is configured with at least two aluminum nitride (ALN) copper-clad insulating plates 3 as required, such as Figure 3As shown, at least two aluminum nitride copper-clad insulating plates 3 are welded to the metal base plate 1 in a matrix structure with spacing between them. Module design and manufacturing typically use AL2O3 ceramic substrates. However, due to the small size and high rated average current of the module designed in this application, in order to conduct the heat generated during operation away from the casing, this application uses an ALN ​​ceramic substrate with a thermal conductivity 7 times higher than that of the AL2O3 ceramic substrate. The thermal conductivity of the ALN ceramic substrate is 230 W / mK. The upper surface of the ALN ceramic substrate is copper-clad. During the design, the insulation voltage requirements were fully considered, and a 0.5 mm blank was left around the perimeter of the board to avoid short circuits caused by solder return during soldering. The area on each aluminum nitride copper-clad insulating plate 3, except for the area corresponding to the sintered fast recovery epitaxial diode chip 4, is not copper-clad and is reserved as a solder resist area.

[0025] The chip lead assembly consists of multiple fast recovery epitaxial diode chips 4, multiple inner leads 5, and one inner lead post 6. The multiple fast recovery epitaxial diode chips 4 are sintered in a matrix structure on an aluminum nitride copper-clad insulating plate 1; the inner leads 5 are transverse U-shaped structures with a width and are made of copper; one end of each inner lead 5 is vacuum eutectic bonded to the fast recovery epitaxial diode chip 4, and the other end is vacuum eutectic bonded to the inner lead post 6.

[0026] In this embodiment, considering that the coefficient of thermal expansion of the molybdenum sheet is close to that of the aluminum nitride copper-clad insulating plate 3, a gold-plated molybdenum sheet is added between the fast recovery epitaxial diode chip 4 and the aluminum nitride copper-clad insulating plate 3 during soldering to reduce the stress exerted by the aluminum nitride copper-clad insulating plate 3 on the fast recovery epitaxial diode chip 4, taking into account wettability issues. Furthermore, since the coefficient of thermal expansion of the molybdenum sheet is very close to that of the silicon wafer, a nickel-plated molybdenum sheet is added between the fast recovery epitaxial diode chip 4 and the inner lead 5 during soldering to reduce the stress exerted by the copper conductor of the inner lead 5 on the fast recovery epitaxial diode chip 4.

[0027] In this embodiment, a specially made graphite mold is used to sequentially place the gold-plated molybdenum sheet 13, the high-temperature solder sheet, the fast recovery epitaxial diode chip 4, the nickel-plated molybdenum sheet, the high-temperature solder sheet, the inner lead 5, and the inner lead post 6 into the graphite mold, and vacuum eutectic weld the chip lead assembly together in a eutectic furnace according to the set temperature curve.

[0028] Since the storage temperature of this series fast recovery epitaxial diode module is -55 to 180℃, in order to achieve the performance specified by the product, four types of Pb92.5Sn5Ag2.5 are selected as solder pads for the chip lead assembly. The melting point of these solder pads is 296℃, which can meet the device's 180℃ requirement.

[0029] In this embodiment of the application, in order to prevent secondary melting of the chip lead assembly, a 220°C hot soldering station for solder paste is used for bonding during secondary soldering.

[0030] After the chip lead assembly is sintered, as shown Figure 4 As shown, the housing base, aluminum nitride copper-clad insulating board 3, chip lead assembly, and housing lead post 7 are then soldered together using a hot soldering station, as follows: Figure 5 As shown, the housing lead post 7 is bridging and soldered onto two aluminum nitride copper-clad insulating boards 3 that need to be connected in series. After cleaning and drying, voltage testing and internal inspection are performed. If no quality problems are found, silicone gel is potted, cured at room temperature for 30 minutes, and then cured in a 100°C oven for 1 hour before use. The void ratio affects the thermal stress and heat dissipation capacity of the product. In this embodiment, the aluminum nitride copper-clad insulating board 3 serves as the insulating layer between the metal base plate 1 and the module interior. To reduce contact voltage drop and void ratio, the flatness of all raw materials must be inspected during the welding of each layer. After inspection, the housing base, aluminum nitride copper-clad insulating board 3, and other components are tinned. The soldering is uniform and the welding is firm to reduce voids between the welding layers, ensuring that the void ratio is controlled within 5% and reducing the device's conduction loss.

[0031] In this embodiment, the inner side of the metal casing 2 is nickel-plated, and its top inner wall is processed into a stepped platform structure B. The stepped platform structure B is denicked after plating for low-temperature welding to the ceramic cover 8 of the outer casing. Figure 6 As shown, both the inner lead post 6 and the housing lead post 7 are designed as T-shaped structures, with a platform C designed around the periphery of the post. When encapsulating the ceramic housing cover 8, low-temperature silicone sealant is evenly applied around the stepped platform of the housing base, the platform C of the inner lead post 6, and the housing lead post 7. The chamfered corner of the ceramic housing cover 8 is then placed downwards onto the housing base, ensuring full contact between the ceramic housing cover 8 and the platform of the housing base, inner lead post 6, and housing lead post 7. After curing in a 90°C oven for 3 hours, a firm bond is achieved, preventing the ceramic housing cover 8 from being pressed down under vertical pressure, resulting in the final series-connected fast recovery epitaxial diode module, as shown. Figure 7 and Figure 8 As shown. The ceramic cover 8 is made of 99.6% high-frequency black ceramic, with an insulation resistance of over 100MΩ, strong corrosion resistance, and is suitable for use in humid and salt spray conditions.

[0032] Both the inner lead post 6 and the outer shell lead post 7 are made of high-quality copper material, with a stable T-shaped structure and strong overload capacity.

[0033] like Figure 9 As shown, the inner lead 5 is a transverse U-shaped structure with a width. This transverse U-shaped structure can prevent external stress from damaging the fast recovery epitaxial diode chip 4. At the same time, the platform on the outer periphery of the inner lead post 6 and the housing lead post 7 is designed as a square, which matches the square hole of the housing ceramic cover 8. After being bonded with low temperature glass glue, it is cured in an oven at 130°C for 3 hours. When the series fast recovery epitaxial diode module is fixed with screws, it can prevent the inner lead 5 from moving.

[0034] After fabricating a series-connected fast recovery epitaxial diode module, this application embodiment implements a high-temperature, high-voltage three-phase rectifier module based on it, such as... Figure 10 , 11 As shown, it consists of three series-connected fast recovery epitaxial diode modules and an aluminum oil tank cover plate 9. The three series-connected fast recovery epitaxial diode modules are mounted flat on the aluminum oil tank cover plate 9 according to the principle that the diode polarity is in one direction. A conical heat conductor 91 is arranged at the bottom of the aluminum oil tank cover plate 9 to increase the heat dissipation area.

[0035] When designing the aluminum oil tank cover plate, factors such as the size of the matching motor, the oil tank pressure, and the flow rate of inlet and outlet oil should be fully considered.

[0036] During assembly, first clean and dry the aluminum fuel tank cover plate 9 to remove oil; then, evenly apply thermal grease to the base plate of the three qualified series fast recovery epitaxial diode modules A, and place the three modules flat on the aluminum fuel tank cover plate 9 according to the principle that the diode polarity is in one direction, align with the mounting holes 10, and tighten the six mounting screws with a torque wrench; finally, clean off the excess thermal grease, and conduct high-temperature storage, temperature cycling, vibration and other tests on the assembled three-phase rectifier modules in sequence. After passing the tests, laser mark them and put them into storage.

[0037] It should be noted that the above description is not intended to limit the present utility model, and the present utility model is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present utility model should also fall within the protection scope of the present utility model.

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