Highly integrated rectification power module

Abstract

The utility model belongs to the field of power semiconductor modules, and particularly discloses a highly-integrated rectification power module which comprises a heat dissipation bottom plate, a copper-clad ceramic substrate, a power semiconductor chip, a bonding wire, a driving resistor, a thermistor, epoxy pouring sealant, a shell and a wiring terminal. A copper-clad ceramic substrate is welded on the heat dissipation bottom plate, and a power semiconductor chip, a driving resistor, an NTC resistor and a wiring terminal are welded on the DBC substrate; and the surface electrode of the power semiconductor chip is electrically connected with the DBC substrate through a bonding wire. The structure is symmetrical, so that the parasitic inductance of a main loop is greatly reduced, better current consistency can be realized, and high-frequency switching is facilitated; kelvin connection is adopted for driving, so that the stability of a driving control circuit is good, and the highly-integrated rectification power module is suitable for being used in a high-strength and high-load state, convenient to debug and better in heat dissipation performance.

Description

Technical Field

[0001] This utility model belongs to the field of power semiconductor modules, and particularly relates to a highly integrated rectifier power module. Background Art

[0002] Rectifier power modules are widely used in frequency converters. With the development of power electronics technology, there is an increasing need for rectifier power modules with small volume, high integration, low cost, and good heat dissipation.

[0003] The rectifier power modules in the prior art mainly have the following disadvantages:

[0004] 1. Due to the asymmetric structure of the electrical circuit, the parasitic inductance is large, and the current consistency is not high, which is not suitable for use in high-frequency switching;

[0005] 2. The integration degree of the power semiconductor chip and the wiring terminal is not high;

[0006] 3. The stability of the drive control circuit is not good;

[0007] 4. The heat conduction ability of the bottom plate material is insufficient, resulting in a relatively high junction-to-case thermal resistance;

[0008] 5. It is difficult to perform temperature detection to reflect the working condition of the module in real time;

[0009] 6. The bottom plate and the shell of the module are integrated, which is not convenient for disassembling with the radiator. Content of the Utility Model

[0010] To solve the above problems, this utility model proposes a highly integrated rectifier power module, which has the advantages of being more suitable for small volume and having small parasitic inductance.

[0011] To achieve the above object, the technical solution adopted by this utility model is:

[0012] A highly integrated rectifier power module includes a DBC substrate, an NTC resistor, the copper foils where two NTC resistors are located, a first group of bridge arms, and a second group of bridge arms;

[0013] The electrical connection contacts at both ends of the NTC resistor are welded to the copper foils where the two NTC resistors are located;

[0014] Each of the first group of bridge arms and the second group of bridge arms includes a MOSFET chip, a DC+ copper foil, a DC+ power terminal, a gate resistor, a drive gate copper foil, a gate drive terminal, an auxiliary source copper foil, an auxiliary source drive terminal, an AC copper foil, an AC power terminal, and a bonding wire;

[0015] The first group of bridge arms and the second group of bridge arms are symmetrically arranged with respect to the first symmetry center line of the DBC substrate;

[0016] The copper foils where the two NTC resistors are located are symmetrically arranged with respect to the first symmetry center line of the DBC substrate.

[0017] Preferably, the front surface of the DBC substrate has an upper copper foil, and the upper copper foil is a copper foil with a concave-convex shape. The transition regions of the concave-convex shape of the upper copper foil are all rounded to reduce stress concentration during the welding process.

[0018] Preferably, the DBC substrate further includes a lower copper foil, and dimple holes are also provided at the four peripheral edges of the lower copper foil;

[0019] The upper copper foil has dimple holes;

[0020] The dimple holes are used to reduce stress concentration.

[0021] Preferably, the upper copper foil and the lower copper foil are 0.5 mm away from the ceramic edge.

[0022] Preferably, the upper copper foil has a solder mask, and the solder mask is used to prevent solder from overflowing during welding.

[0023] Preferably, the minimum distance between the copper foils is 0.6 mm to meet the insulation withstanding voltage during design.

[0024] Preferably, slender terminals are welded to the driving gate copper foil, the auxiliary source copper foil, and the copper foils where the NTC resistors are located, and the diameter of the slender terminals is 0.8 mm;

[0025] The DBC substrate also has an AC power terminal, a DC+ power terminal, and a DC- power terminal. The AC power terminal, the DC+ power terminal, and the DC- power terminal are thick and short terminals, and the diameter of the thick and short terminals is 2 mm.

[0026] Preferably, an outer shell is sleeved outside the DBC substrate. The bottom of the outer shell is bonded to the copper bottom plate. Epoxy resin is filled inside the outer shell, and the epoxy resin seals the MOSFET chip, the DBC substrate, and the bonding wires.

[0027] Preferably, the outer shell and the copper bottom plate are fixedly connected by screws to facilitate disassembly from an external radiator.

[0028] Preferably, the encapsulation method of the highly integrated rectifier power module includes the following steps:

[0029] Prepare a corresponding copper-clad ceramic substrate according to the structure of the power module to be encapsulated, etch the front metal layer and the bottom metal layer of the copper-clad ceramic substrate, and then perform surface nickel plating treatment;

[0030] The power chip and the driving resistor are soldered or sintered to the corresponding copper foil positions of the copper-clad ceramic substrate using the first solder;

[0031] The surface electrodes of the power semiconductor chip and the copper foil of the copper-clad ceramic substrate are electrically connected through a wire bonding process;

[0032] The driving terminals, power terminals, and copper base plate are simultaneously re-soldered using the second solder.

[0033] The housing is fixed to the copper base plate, epoxy gel is injected into the housing, evacuated, and then heated or left to cure at room temperature to cure the epoxy gel.

[0034] The beneficial effects of using this utility model are as follows:

[0035] The structure of this highly integrated rectifier power module is symmetric, greatly reducing the parasitic inductance of the main circuit, and achieving good current consistency, which is beneficial for high-frequency switching. The highly integrated power semiconductor chip and wiring terminals are achieved through a compact DBC layout. The driving uses Kelvin connection, resulting in good stability of the drive control circuit. The high thermal conductivity DBC material and copper base plate can achieve a low junction-to-case thermal resistance. The thermistor is used for temperature detection to reflect the working condition of the module in real time. The module base plate and housing adopt a screw fastening scheme, which is convenient for disassembly from the radiator and facilitates the maintenance and installation of the frequency converter. Description of the Drawings

[0036] Figure 1 It is a top view schematic diagram of the substrate in this highly integrated rectifier power module of the present utility model.

[0037] Figure 2 It is a bottom view schematic diagram of the substrate in this highly integrated rectifier power module of the present utility model.

[0038] Figure 3 It is a side view schematic diagram of the substrate in this highly integrated rectifier power module of the present utility model.

[0039] Figure 4 It is a layout schematic diagram of the chip in this highly integrated rectifier power module of the present utility model.

[0040] Figure 5 It is an axonometric view schematic diagram of the chip in this highly integrated rectifier power module of the present utility model.

[0041] Figure 6 It is a schematic diagram of the structure of the driving and power terminals in this highly integrated rectifier power module of the present utility model.

[0042] Figure 7 It is a top view schematic diagram of the whole of this highly integrated rectifier power module of the present utility model.

[0043] Figure 8This is the overall axonometric schematic diagram of the highly integrated rectifier power module of the present utility model.

[0044] Figure 9 This is the circuit topology diagram of the highly integrated rectifier power module of the present utility model.

[0045] Figure 10 This is the flow chart of the packaging method of the highly integrated rectifier power module of the present utility model. Specific embodiments

[0046] To make the purpose, technical solutions and advantages of the present technical solution clearer, the present technical solution will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary and not intended to limit the scope of the present technical solution.

[0047] As Figures 1 - 3 shown, in this embodiment, the DBC substrate 1 includes three layers: the upper copper foil 5-14, the middle ceramic layer 2, and the lower copper foil 3; the upper copper foil 5-14 includes the gate resistance copper foils 5, 6, the driving gate copper foils 7, 8, the auxiliary source copper foils 9, 10, the DC+ copper foil 11, the DC- copper foil 12, the copper foil 13 where the NTC resistor 29 is located, and the solder mask of the upper DBC copper foil. The upper copper foil 5-14 is arranged symmetrically under the minimum electrical clearance, which can reduce the parasitic inductance of the main circuit and achieve current consistency. The upper copper foil 5-14 is designed in a concave-convex shape for convenient welding. The transition areas of the concave-convex shape are all rounded to reduce stress concentration during welding. In addition, the dimple holes 4 of the upper copper foil 5-14 and the lower copper foil 3 can also reduce stress concentration. There is a solder mask 14 on the upper copper foil 5-14 to prevent solder from overflowing when the chip, resistor and the upper copper foil 5-14 are welded, and to prevent electrical short circuits during use.

[0048] The upper copper foil 5-14 and the lower copper foil 3 are 0.5 mm away from the ceramic edge, and the minimum distance between the copper foils is 0.6 mm, which can meet the insulation withstand voltage during design. The materials of the middle ceramic layer 2 include alumina, aluminum nitride, alumina doped with zirconia, silicon nitride, and aluminum nitride. Among them, aluminum nitride has the highest thermal conductivity, so aluminum nitride ceramic is selected.

[0049] As Figures 4 - 6As shown, the power semiconductor chips 15-20 and the connection terminals are placed in pairs. Among the connection terminals, the gate drive terminals 22, 25, the auxiliary source drive terminal slender terminals 21, 24, and the NTC resistor 29 terminals 28 (28-1, 28-2) are slender segments, and the diameter of the slender segments is 0.8 mm; the DC+ power terminal 23, the DC- power terminal 26, and the AC power terminals 28 (28-1, 28-2) are thick and short terminals, and the diameter of the thick and short terminals is 2 mm. The number and diameter of the terminals are determined according to the current-carrying capacity of the module design. The surface of the terminals is generally nickel-plated + gold-plated, which can resist moisture, mildew, and salt spray and enhance the service life.

[0050] The potentials of the thick and short terminals on the same copper foil are the same. Therefore, the minimum distance between terminals such as 23 is at least 1 mm for convenient soldering. The potentials of the thick and short terminals on different copper foils are different. At this time, the minimum distance between terminals such as the DC+ power terminal 23 and the AC power terminals 27 (27-1, 27-2, 27-3) is at least greater than 5 mm to meet the creepage distance of the design.

[0051] There are bonding wires 15a-20a, 15b-20b, 15d-20d on the chip. The number of bonding wires is determined according to the area of the bondable region of the chip electrodes, and the thickness of the bonding wires is determined according to the characteristics of the chip electrodes and the usage occasions. Generally, the power source electrode of the chip is the thick wire 15d-20d, and the drive gate and auxiliary source electrodes of the chip are the thin wires 15a-20a, 15b-20b. The bonding wire material can be selected from aluminum bonding wires, copper bonding wires, etc. The electrical conductivity and thermal conductivity of copper wires are better than those of aluminum wires. Therefore, copper bonding wires are selected for connection in this article. The NTC resistor 29 can monitor the health status of the module during operation.

[0052] As Figure 7 and Figure 8 As shown, the bottom of the housing 31 is bonded to the copper base plate 30 and is fixed in position by the combination screw washer 33. There is epoxy resin 32 in the housing 31 to protect the internal components of the module from external contamination. There are small protrusions 34 for protection left on the top of the housing 31 to facilitate the connection and positioning of the external PCB. Both the housing and the copper base plate adopt a screw fastening scheme, which is convenient for disassembly from the radiator and facilitates the maintenance and installation of the frequency converter. The housing 31 is made of PBT material with anti-plastic deformation, anti-thermal deformation, and electrical insulation properties. The height of the housing is designed to be 7.5 mm. At this time, the epoxy potting adhesive can cover the arc height of the chip, DBC, and bonding wires to ensure that the three are not affected by external environmental pollution.

[0053] Combined Figure 9As shown, the drains of the three MOSFET chips 15 - 17 in the first set of bridge arms are all soldered to the DC+ copper foil 11, and then connected to the external circuit through the DC+ power terminal 23. Their gates are respectively connected to the driving gate copper foil 7 through the gate driving bonding wires 15a - 17a and the gate resistors 15c - 17c, and then connected to the external circuit through the gate driving terminal 22. Their auxiliary sources are respectively connected to the auxiliary source copper foil 9 through the auxiliary source bonding wires 15b - 17b, and then connected to the external circuit through the auxiliary source driving terminal 21. Their power sources are connected to the AC copper foil 9 through the power source bonding wires 15d - 17d, and then connected to the external circuit through the AC connection terminals 27 (27 - 1, 27 - 2, 27 - 3).

[0054] The drains of the three MOSFET chips 18 - 20 in the second set of bridge arms are all soldered to the DC- copper foil 12, and then connected to the external circuit through the DC- power terminal 26. Their gates are respectively connected to the driving gate copper foil 8 through the gate driving bonding wires 18a - 20a and the gate resistors 18c - 20c, and then connected to the external circuit through the gate driving terminal 25. Their auxiliary sources are respectively connected to the auxiliary source copper foil 10 through the auxiliary source bonding wires 18b - 20b, and then connected to the external circuit through the auxiliary source driving terminal 24. Their power sources are connected to the AC copper foil 9 through the power source bonding wires 18d - 20d, and then connected to the external circuit through the AC connection terminal 27.

[0055] The highly integrated rectifier power module has a symmetrical structure, which greatly reduces the parasitic inductance of the main circuit, and can achieve good current consistency, which is beneficial to high - frequency switching. The highly integrated power semiconductor chips and connection terminals are realized through a compact DBC layout. The driving adopts the Kelvin connection, which makes the driving control circuit have good stability. The DBC substrate 1 with high thermal conductivity and the copper base plate 30 can achieve a low junction - to - case thermal resistance. The NTC resistor 29 is used for temperature detection to reflect the working condition of the module in real time. The copper base plate 30 and the shell 31 of the module adopt a screw fastening scheme, which is convenient for disassembly with the radiator and facilitates the maintenance and installation of the frequency converter.

[0056] As Figure 10 shown, this embodiment also proposes a packaging method for the above - mentioned highly integrated rectifier power module, which includes the following steps:

[0057] Prepare a corresponding copper - clad ceramic substrate according to the structure of the power module to be packaged, etch the front - side metal layer and the bottom - side metal layer of the copper - clad ceramic substrate, and then perform surface nickel plating treatment;

[0058] Use the first solder to weld or sinter the power chips and driving resistors to the corresponding copper foil positions of the copper - clad ceramic substrate;

[0059] Electrically connect the surface electrode of the power semiconductor chip to the copper foil of the copper-clad ceramic substrate through a wire bonding process;

[0060] Use a second solder to perform secondary soldering on the drive terminal, power terminal, and copper base plate 30 simultaneously.

[0061] Fix the housing 31 on the copper base plate 30, inject epoxy gel into the housing 31, evacuate, and then heat or let it stand at room temperature to cure the epoxy gel to form an epoxy potting compound formed by the epoxy resin 32.

[0062] The traditional easy1B and easy2B module packages with pin pins have a bottomless structure. The power semiconductor module in this application has both terminals and a copper base plate, and the terminals and the copper base plate 30 are soldered simultaneously during the above packaging manufacturing process.

[0063] The above content is only the preferred embodiment of this utility model. For those of ordinary skill in the art, according to the idea of the technical content of this technology, many changes can be made in the specific implementation manner and application scope. As long as these changes do not depart from the concept of this utility model, they all belong to the protection scope of this patent.

Claims

1. A highly integrated rectifier power module, characterized in that: It includes a DBC substrate, an NTC resistor, copper foils where two NTC resistors are located, a first group of bridge arms, and a second group of bridge arms; The electrical connection contacts at both ends of the NTC resistor are welded to the copper foil where the two NTC resistors are located; The first group of bridge arms and the second group of bridge arms each include a MOSFET chip, a DC+ copper foil, a DC+ power terminal, a gate resistor, a driving gate copper foil, a gate driving terminal, an auxiliary source copper foil, an auxiliary source driving terminal, an AC copper foil, an AC power terminal, and a bonding wire; The first group of bridge arms and the second group of bridge arms are symmetrically arranged about a first symmetric center line of the DBC substrate; The copper foils where the two NTC resistors are located are symmetrically arranged about the first symmetry center line of the DBC substrate.

2. The highly integrated rectifier power module according to claim 1, characterized in that: The front side of the DBC substrate has an upper copper foil, which is a copper foil with a concave-convex shape. The transition areas of the concave-convex shapes of the upper copper foil are all rounded to reduce stress concentration during welding.

3. The highly integrated rectifier power module according to claim 2, characterized in that: The DBC substrate also includes a lower copper foil, and the lower copper foil has dimple holes around its edges; The upper copper foil has a dimple hole; The dimple holes are used to reduce stress concentration.

4. The highly integrated rectifier power module according to claim 3, characterized in that: The upper copper foil and the lower copper foil are 0.5 mm away from the edge of the ceramic.

5. The highly integrated rectifier power module according to claim 2, characterized in that: The upper copper foil has a solder resist, which is used to prevent solder from overflowing during soldering.

6. The highly integrated rectifier power module according to claim 1, characterized in that: The minimum spacing between the copper foils is 0.6 mm to meet the insulation withstand voltage requirements during design.

7. The highly integrated rectifier power module according to claim 1, characterized in that: The driving gate copper foil, the auxiliary source copper foil and the copper foil where the NTC resistor is located are all welded with slender terminals, and the diameter of the slender terminals is 0.8 mm; The DBC substrate further has an AC power terminal, a DC+ power terminal and a DC- power terminal. The AC power terminal, the DC+ power terminal and the DC- power terminal are short and thick terminals with a diameter of 2 mm.

8. The highly integrated rectifier power module according to claim 1, characterized in that: The DBC substrate is covered with a shell, the bottom of the shell is bonded to the copper bottom plate, the shell is filled with epoxy resin, and the epoxy resin seals the MOSFET chip, the DBC substrate and the bonding wires.

9. The highly integrated rectifier power module according to claim 8, characterized in that: The shell and the copper bottom plate are fastened and connected by screws to facilitate disassembly from the external radiator.

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