An IGBT electrical unit package

Abstract

The present invention relates to the field of semiconductor packaging technology, and in particular to an IGBT electrical unit package. The IGBT electrical unit package provided by the present invention includes: a heat dissipation base plate, a housing, a cover plate and an IGBT electrical unit. In the present invention, the heat dissipation base plate adopts an AlSiC composite material with a volume fraction of 52%-58%, the IGBT electrical unit package adopts an AlN ceramic direct copper-clad substrate, and the connection between the insulated gate bipolar transistor chip, the diode chip and the ceramic direct copper-clad substrate adopts a nano-Ag solder paste low-pressure sintering process. The IGBT electrical unit package in the present invention adopts a packaging structure with high airtightness to ensure that the IGBT electrical unit package will not have a decrease in the internal pressure resistance of the IGBT electrical unit package due to a decrease in air pressure when it is used in high-altitude applications such as when it is installed on a transport aircraft or a fighter jet, thereby ensuring the reliability of the IGBT electrical unit package.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to an IGBT electrical unit package. Background Art

[0002] With its many advantages, such as low power consumption, simple driving, high current density, and low saturation voltage drop, the insulated gate bipolar transistor (IGBT) has become one of the core components of power electronics systems. It is widely used in many key areas such as electric vehicles, new energy power generation, smart grids, rail transportation, and high-voltage power transmission. It is also a key component in the power supply and distribution systems of weapons and equipment, motor drive systems, and servo systems. Its quality and reliability are of great significance to the operation of equipment.

[0003] Semiconductor devices, especially power devices, require a certain amount of power during operation. Most of this power is converted into heat, causing the device chip to temperature rise. The heat on the chip is transferred to the outer casing through the chip sintering material, and further to the surrounding air (sometimes through a heat sink for power devices). Thermal resistance is a physics concept that refers to the resistance encountered by heat flow (power) when flowing through a heat conductor (which creates a temperature difference across the heat conductor). The reciprocal of thermal resistance is thermal conductivity. In layman's terms, an object with good thermal conductivity has low thermal resistance.

[0004] For high-power modules, thermal resistance refers to the steady-state thermal resistance from the chip to the module case (directly below the chip), called the junction-to-case thermal resistance, usually expressed as:

[0005]

[0006] Where Tj is the chip junction temperature, Tc is the module housing design location temperature, and P is the dissipated power.

[0007] As IGBT module voltage levels and switching frequencies increase, switching losses continue to rise, and internal module heat generation continues to increase. The operating characteristics of IGBT modules are significantly affected by temperature. Semiconductor physical constants and internal device parameters vary with temperature, leading to changes in performance indicators such as the IGBT module's turn-on and turn-off speeds, and on-state voltage drop. Existing IGBT module packaging structures have low reliability in low-voltage environments. These existing IGBT module packaging structures also have high junction-to-case thermal resistance, which negatively impacts reliability. Summary of the Invention

[0008] In view of the above problems existing in the prior art, the present invention provides an IGBT electrical unit package having smaller junction-to-case thermal resistance and higher reliability and applicable to low-voltage use environments.

[0009] The IGBT electrical unit package provided by the present invention includes: a heat dissipation base plate, a shell, a cover plate and an IGBT electrical unit. The IGBT electrical unit is welded to the upper surface of the heat dissipation base plate, the lower part of the shell and the heat dissipation base plate are fixedly bonded in a gas-tight manner using a sealant, and the upper part of the shell and the cover plate are fixedly bonded in a gas-tight manner using a sealant.

[0010] Silicon gel is poured into the lower part of the accommodating cavity formed by the heat dissipation base plate and the shell to form a sealing structure, and the IGBT electrical unit is basically contained in the silicone gel.

[0011] An anti-deformation layer is provided on the silicone gel, and the anti-deformation layer is located below the cover plate.

[0012] The IGBT electrical unit soldered to the heat sink baseplate is essentially contained within the sealed structure formed by the silicone gel, creating an airtight seal for the IGBT electrical unit. Because the sealed structure is free of gas, the interior of the IGBT electrical unit is protected from the effects of the external low-pressure environment. In a low-pressure environment, gas trapped in the tiny gaps between the internal terminals of the IGBT electrical unit and the heat sink baseplate, between the outer casing and the heat sink baseplate, and between the ceramic copper-clad substrate and the IGBT and diode chips cannot escape into the silicone gel.

[0013] The silicone gel includes a ceramic copper-clad substrate, the insulated gate bipolar transistor chip, the diode chip, and all the metal bonding wires, and an anti-deformation layer is provided on the silicone gel. For semiconductor devices, a certain amount of power must be applied during operation, and most of this power is converted into heat, causing the temperature of the device chip to rise. The heat of the insulated gate bipolar transistor chip and the diode chip on the IGBT electrical unit is transferred to the casing through the welding sintered material, and further transferred to the surrounding air environment. This part of energy is also transferred to the silicone gel. The silicone gel is affected by temperature and then produces volume expansion. In a low-pressure environment, the external air pressure to which the silicone gel is subjected is significantly lower than in a normal 1 atmosphere environment, which also causes the softer silicone gel to expand in volume. The harder anti-deformation layer has a certain mechanical compression effect, which can effectively prevent the silicone gel from deforming due to air pressure and heat.

[0014] According to one aspect of the present invention, the lower portion of the housing and the heat dissipation base are fixedly bonded using epoxy glue, and the upper portion of the housing and the cover are fixedly bonded using epoxy glue;

[0015] The anti-deformation layer is a silicone rubber layer. Silicone rubber can be used at temperatures between 150 degrees and minus 350 degrees Celsius, and still has good elasticity at temperatures between minus 60 degrees Celsius and minus 70 degrees Celsius. It also has good chemical stability. Therefore, the anti-deformation layer made of silicone rubber can be used at higher operating temperatures without changing its shape or properties.

[0016] Epoxy adhesive offers high strength, good toughness, and excellent point insulation properties. It can be used for long periods of time at temperatures between -80°C and 200°C. It also exhibits excellent chemical stability, minimal shrinkage after curing, and strong bonding properties. The heat sink and housing are bonded together using epoxy adhesive. The anti-deformation layer, along with the heat sink and housing, helps maintain the silicone gel's volume stability at high temperatures and low pressures, thereby ensuring the reliability of the IGBT electrical units encapsulated within these layers, the heat sink, and the housing.

[0017] According to one aspect of the present invention, the ratio between the hardness of the sealing structure and the hardness of the deformation-preventing layer is 1:(3-4).

[0018] Hardness is related to compressive strength. Silicone gel with low hardness is less able to withstand force, while silicone rubber with high hardness exhibits high compressive strength. Specifically, the silicone rubber layer of the anti-deformation layer is harder than the silicone gel. The softer silicone gel does not generate compressive stress on the metal bonding wires and can protect them.

[0019] According to one aspect of the present invention, the housing is made of a material having a ratio of a thermal expansion coefficient to a thermal expansion coefficient of the epoxy adhesive of (0.8-1.2):1;

[0020] Preferably, the housing is made of a material having a thermal expansion coefficient similar to that of the epoxy adhesive, so that when heated, the volume of the housing expands together with the cured epoxy adhesive, thereby avoiding the formation of a gap between the epoxy adhesive and the housing at higher operating temperatures.

[0021] According to one aspect of the present invention, the sealing structure is an 8mm-12mm silicone gel arranged at the lower part of the accommodating cavity formed by the heat dissipation base plate and the outer shell, and the anti-deformation layer is a 1mm-2mm silicone rubber arranged on the silicone gel, wherein the silicone gel and the silicone rubber are subjected to vacuum degassing treatment.

[0022] The silicone gel, with a thickness ranging from 8mm to 12mm, effectively protects the ceramic copper-clad substrate, the insulated gate bipolar transistor chip, the diode chip, and all metal bonding wires, preventing problems such as lead leakage and insufficient voltage resistance. The silicone rubber of the anti-deformation layer is disposed on the silicone gel. The silicone rubber has a thickness of 1-2mm, which is suitable for its high hardness and effectively prevents the silicone gel from bubbling in low-pressure environments. A certain space is also left between the anti-deformation layer and the cover plate to prevent thermal expansion of the silicone rubber and silicone gel from squeezing the cover plate and the housing.

[0023] Silicone rubber and silicone gel undergo vacuum degassing treatment to eliminate microbubbles. When IGBT electrical units are used in low-voltage environments, although there is a pressure difference inside and outside the IGBT electrical unit, there will be no local discharge of microbubbles under the action of a high-voltage electric field, and it will not cause aging and decomposition of the organic insulating potting body, thereby improving the reliability of the IGBT electrical unit package.

[0024] According to one aspect of the present invention, the IGBT electrical unit comprises:

[0025] A ceramic copper-clad substrate, welded to the heat dissipation base plate, wherein the ceramic copper-clad substrate includes a power substrate and a signal substrate separated from each other, and the power substrate and the signal substrate are bonded to each other via metal bonding wires;

[0026] an insulated gate bipolar transistor chip and a diode chip, wherein the insulated gate bipolar transistor chip and the diode chip are welded on the power substrate and connected by metal bonding wires; and

[0027] The signal terminal and the power terminal are respectively welded to the ceramic copper-clad substrate using a brazing process, wherein the fixed end of the signal terminal is brazed to the signal substrate, the fixed end of the power terminal is brazed to the power substrate, and the free end of the signal terminal and the free end of the power terminal extend from the opening of the housing or the cover;

[0028] The welding position of the fixed end of the power terminal on the power substrate, the welding position of the insulated gate bipolar transistor chip on the power substrate and the welding position of the diode chip on the power substrate are separated from each other;

[0029] The power substrate, the signal substrate, the insulated gate bipolar transistor chip, the diode chip, the metal bonding wires, the lower portion of the signal terminal and the lower portion of the power terminal of the IGBT electrical unit are contained in the silicone gel;

[0030] The heat dissipation base plate is made of a composite material containing 52%-58% by volume of AlSiC;

[0031] The ceramic copper-clad substrate is an AlN ceramic copper-clad substrate;

[0032] The insulated gate bipolar transistor chip and the diode chip are connected to the power substrate of the AlN ceramic copper-clad substrate by welding using nano-Ag solder paste and a low-temperature and low-pressure welding process.

[0033] The heat dissipation base plate of the present invention adopts 52%-58% volume fraction of AlSiC composite material. Compared with the traditional base plate, the density is increased from 7.8g / cm 3 Down to 2.99g / cm 3 , the module weight is greatly reduced under the same volume.

[0034] According to one aspect of the present invention, the back electrode of the insulated gate bipolar transistor chip and the back electrode of the diode chip are welded to the surface of the power substrate of the AlN ceramic copper-clad substrate. During the welding process, the insulated gate bipolar transistor chip and the diode chip are subjected to a pressure of 5MPa-11MPa, a sintering temperature of 200°C-300°C, and a holding time of 40s-60s.

[0035] An AlN ceramic direct copper-clad substrate is used. Compared with the traditional alumina ceramic copper-clad substrate, the thermal conductivity of AlN ceramic is increased by nearly 10 times. The connection between the insulated gate bipolar transistor chip, the diode chip and the ceramic direct copper-clad substrate adopts a nano-Ag solder paste low-pressure sintering process. Compared with traditional high-lead solder, the thermal conductivity of the interconnection joint is increased by more than 3 times, and the temperature resistance is not less than 200°C, which further improves the reliability of the IGBT electrical unit.

[0036] According to one aspect of the present invention, an ultrasonic bonding process and aluminum bonding wires are used to form electrical connections between the front electrodes of the insulated gate bipolar transistor chip and the front electrodes of the diode chip and the surface copper clad layer of the power substrate of the AlN ceramic copper clad substrate;

[0037] The power substrate and the signal substrate are connected by aluminum bonding wires.

[0038] The power substrate, the signal substrate and the heat dissipation base plate are electrically connected by a vacuum brazing process and tin-lead eutectic solder.

[0039] The electrical connection between the fixed end of the signal terminal and the signal substrate and the electrical connection between the fixed end of the power terminal and the power substrate are formed by a hot air reflow process and tin-lead eutectic solder.

[0040] Ultrasonic bonding involves applying ultrasonic waves to aluminum bonding wires, which exerts a similar effect on the material's plastic deformation as heating. The ultrasonic energy is selectively absorbed by dislocations in the aluminum bonding wire, freeing them from their restrained positions. This allows the aluminum bonding wire to enter a state of plastic deformation even with minimal external force. This deformation of the aluminum bonding wire destroys the oxide film formed on the surface of the vapor-deposited aluminum film, exposing a clean metal surface that facilitates bonding.

[0041] According to one aspect of the present invention, the device further comprises a gate resistor and a Zener diode, and the gate resistor, the Zener diode and the surface of the signal substrate are electrically connected by a soldering process.

[0042] The gate-emitter or gate-source connection of insulated gate bipolar transistor (IGBT) and diode chips is capacitive, and parasitic inductance in the gate loop is unavoidable. Ideally, a series gate resistor is used to eliminate strong gate oscillations in the gate loop when stimulated by the driver's drive pulse. The gate resistor also serves to transfer power loss from the driver, reducing temperature rise. Surface gate breakdown can cause failure of the IGBT electrical unit package.

[0043] According to one aspect of the present invention, a bent portion is provided at the free end of the power terminal extending out of the cover plate or the housing, a through hole is provided at the bent portion of the power terminal, and a mounting base with a threaded hole is provided on the cover plate, and the position of the mounting base matches the through hole.

[0044] The present invention has the following beneficial effects: the IGBT electrical unit package of the present invention can meet higher requirements on reliability, weight and other indicators of the IGBT electrical unit package in a higher operating temperature environment by reducing the package thermal resistance of the IGBT module.

[0045] The IGBT electrical unit package of the present invention utilizes an AlN ceramic direct-copper-clad substrate. Compared to conventional alumina ceramic direct-copper-clad substrates, the thermal conductivity of AlN ceramic is nearly 10 times greater. The connections between the insulated gate bipolar transistor chip, the diode chip, and the ceramic direct-copper-clad substrate utilize a nano-Ag solder paste low-pressure sintering process. Compared to conventional high-lead solder, the thermal conductivity of the interconnect joints is increased by more than 3 times, and the temperature resistance is no less than 200°C, further enhancing the reliability of the IGBT electrical unit package in higher operating temperature environments. The IGBT electrical unit package of the present invention utilizes a highly airtight packaging structure, ensuring that when the IGBT electrical unit package is used in high-altitude applications, such as when installed on an aircraft, the internal pressure resistance of the IGBT electrical unit package will not decrease due to a decrease in air pressure, thereby ensuring the reliability of the IGBT electrical unit package. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic structural diagram of an IGBT electrical unit according to an embodiment of the present invention;

[0047] Figure 2 is a perspective view of an IGBT electrical unit package according to one embodiment of the present invention;

[0048] Figure 3 This is a diagram showing the arrangement structure of a ceramic copper-clad substrate of an IGBT electrical unit according to an embodiment of the present invention;

[0049] Figure 4 It is a schematic structural diagram of an IGBT electrical unit package according to an embodiment of the present invention.

[0050] Figure numbers: 1-heat sink; 2-power substrate; 3-signal substrate; 4-insulated gate bipolar transistor chip; 5-diode chip; 6-power terminal; 7-signal terminal; 8-aluminum bonding wire; 9-mounting base; 10-through hole; 11-housing; 12-cover; 13-epoxy glue; 14-silicone gel; 15-silicone rubber; DETAILED DESCRIPTION

[0051] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0052] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

[0053] like Figure 1 、 Figure 2 and Figure 4 As shown, an IGBT electrical unit package according to an embodiment of the present invention includes: a heat dissipation base plate 1, a housing 11, a cover plate 12, and an IGBT electrical unit. The IGBT electrical unit is welded to the upper surface of the heat dissipation base plate 1. The lower portion of the housing 11 and the heat dissipation base plate 1 are fixedly bonded in a gas-tight manner using a sealant. The upper portion of the housing 11 and the cover plate 12 are fixedly bonded in a gas-tight manner using a sealant.

[0054] Silicone gel 14 is encapsulated in the lower portion of the accommodating cavity formed by the heat dissipation base plate 1 and the housing 11 to form a sealed structure. The IGBT electrical unit is basically contained in the silicone gel 14.

[0055] An anti-deformation layer is provided on the silicone gel 14 and is located below the cover plate 12 .

[0056] The IGBT electrical unit soldered to the heat sink baseplate 1 is essentially contained within the sealed structure formed by the silicone gel 14, creating an airtight seal. Because the sealed structure is gas-free, the interior of the IGBT electrical unit is protected from the effects of the external low-pressure environment. In this low-pressure environment, gas trapped in the tiny, enclosed spaces formed by the tiny gaps between the IGBT electrical unit's internal terminals and the heat sink baseplate 1, between the housing 11 and the heat sink baseplate 1, and between the ceramic copper-clad substrate and the insulated gate bipolar transistor chip 4 and diode chip 5, cannot escape into the silicone gel 14.

[0057] The silicone gel 14 comprises a ceramic copper-clad substrate, an insulated gate bipolar transistor chip 4, and a diode chip 5, and contains all metal bonding wires. An anti-deformation layer is provided on the silicone gel 14. Semiconductor devices require a certain amount of power during operation, and the vast majority of this power is converted into heat, causing the device chip to temperature rise. The heat from the insulated gate bipolar transistor chip 4 and the diode chip 5 on the IGBT electrical unit is transferred to the housing 11 through the soldering sintered material, and further to the surrounding air. This energy is also transferred to the silicone gel 14. The silicone gel 14 is affected by temperature and expands in volume. In a low-pressure environment, the external air pressure to which the silicone gel 14 is subjected is significantly lower than in a normal 1 atmosphere environment, which also causes the softer silicone gel 14 to expand in volume. The harder anti-deformation layer exerts a certain mechanical compressive effect, effectively preventing the silicone gel 14 from deforming due to air pressure and heat.

[0058] In this embodiment, epoxy glue is used to securely bond the lower portion of the housing 11 to the heat dissipation base plate 1 , and epoxy glue is used to securely bond the upper portion of the housing 11 to the cover plate 12 .

[0059] The anti-deformation layer is a silicone rubber layer;

[0060] Epoxy adhesive 13 has high strength, good toughness, and excellent point insulation properties. It can be used for long periods of time at temperatures between -80°C and 200°C. It also exhibits excellent chemical stability, minimal shrinkage after curing, and strong bonding properties. Heat sink base plate 1 and housing 11 are bonded together using epoxy adhesive 13. The anti-deformation layer, together with heat sink base plate 1 and housing 11, helps maintain the volume of silicone gel 14 at high temperatures and low pressures, thereby ensuring the reliability of the IGBT electrical unit encapsulated within the anti-deformation layer, heat sink base plate 1, and housing 11 during use.

[0061] In this embodiment, the ratio between the hardness of the sealing structure and the hardness of the deformation preventing layer is 1:3.

[0062] The degree of hardness is related to the variation in compressive strength. Silicone gel 14 with low hardness is less able to withstand force, while silicone rubber 15 with high hardness has high compressive strength. Specifically, the silicone rubber 15 in the anti-deformation layer has a harder hardness than the silicone gel 14. The softer silicone gel 14 does not generate compressive stress on the metal bonding wires and can protect them.

[0063] In this embodiment, the housing 11 is made of epoxy resin;

[0064] Preferably, the housing 11 made of epoxy resin having the same thermal expansion coefficient as the epoxy adhesive 13 will expand in volume together with the cured epoxy adhesive 13 when heated, thereby avoiding the generation of a gap between the epoxy adhesive 13 and the housing 11 at higher operating temperatures.

[0065] In this embodiment, the sealing structure is an 8mm-12mm silicone gel 14 arranged at the lower part of the accommodating cavity formed by the heat dissipation base plate 1 and the outer shell 11, and the anti-deformation layer is a 1mm-2mm silicone rubber 15 arranged on the silicone gel 14, wherein the silicone gel 14 and the silicone rubber 15 are subjected to vacuum degassing treatment.

[0066] The silicone rubber 15 and the silicone gel 14 are subjected to vacuum degassing treatment to eliminate microbubbles. When the IGBT electrical unit is used in a low-pressure environment, although there is a pressure difference between the inside and outside of the IGBT electrical unit, there will be no local discharge of microbubbles under the action of a high-voltage electric field, and the organic insulating potting body will not be aged and decomposed, thereby improving the reliability of the IGBT electrical unit package.

[0067] The silicone gel 14, with a thickness ranging from 8mm to 12mm, effectively protects the power substrate 2, signal substrate 3, insulated gate bipolar transistor chip 4, diode chip 5, and all metal bonding wires of the ceramic copper-clad substrate, preventing problems such as lead leakage and insufficient withstand voltage. The anti-deformation layer of silicone rubber 15 is disposed on the silicone gel 14. The silicone rubber 15 has a thickness of 1mm to 2mm, a suitable thickness with high hardness, effectively preventing the silicone gel 14 from bubbling in low-pressure environments. It also leaves a certain space between the anti-deformation layer and the cover plate 12 to prevent thermal expansion of the silicone rubber 15 and silicone gel 14 from squeezing the cover plate 12 and the housing 11.

[0068] like Figure 1 、 Figure 2 、 Figure 3 As shown, in this embodiment, the IGBT electrical unit includes:

[0069] A ceramic copper-clad substrate is welded on the heat dissipation base plate 1, wherein the ceramic copper-clad substrate includes a power substrate 2 and a signal substrate 3 that are separated from each other, and the power substrate 2 and the signal substrate 3 are bonded together by aluminum bonding wires 8;

[0070] An insulated gate bipolar transistor chip 4 and a diode chip 5 are welded on the power substrate 2 and bonded together via an aluminum bonding wire 8; and

[0071] The signal terminal 7 and the power terminal 6 are respectively soldered to the ceramic copper-clad substrate using a brazing process. The fixed end of the signal terminal 7 is brazed to the signal substrate 3, and the fixed end of the power terminal 6 is brazed to the power substrate 2. The free ends of the signal terminal 7 and the power terminal 6 extend through the openings of the housing 11 or the cover 12.

[0072] The welding position of the fixed end of the power terminal 6 on the power substrate 2, the welding position of the insulated gate bipolar transistor chip 4 on the power substrate 2 and the welding position of the diode chip 5 on the power substrate 2 are separated from each other;

[0073] The power substrate 2, signal substrate 3, insulated gate bipolar transistor chip 4, diode chip 5, aluminum bonding wire 8, lower portion of signal terminal 7 and lower portion of power terminal 6 of the IGBT electrical unit are contained in the silicone gel 14;

[0074] The heat dissipation base plate 1 is made of a composite material containing 55% volume fraction of AlSiC;

[0075] The ceramic copper-clad substrate is an AlN ceramic copper-clad substrate;

[0076] The insulated gate bipolar transistor chip 4 and the diode chip 5 are connected to the power substrate 2 of the AlN ceramic copper-clad substrate by welding using nano-Ag solder paste and a low-temperature and low-pressure welding process.

[0077] The IGBT electric unit in this embodiment is a half-bridge IGBT electric unit.

[0078] In this embodiment, the heat dissipation base plate 1 adopts 55% volume fraction of AlSiC composite material, and the density is increased from 7.8g / cm 3 Down to 2.99g / cm 3 , the module weight is greatly reduced under the same volume.

[0079] In this embodiment, the back electrode of the insulated gate bipolar transistor chip 4 and the back electrode of the diode chip 5 are welded to the surface of the power substrate 2 of the AlN ceramic copper-clad substrate. During the welding process, the insulated gate bipolar transistor chip 4 and the diode chip 5 are subjected to a pressure of 8 MPa, a sintering temperature of 250°C, and a holding time of 50 seconds.

[0080] An AlN ceramic direct copper-clad substrate is used. Compared with the traditional alumina ceramic copper-clad substrate, the thermal conductivity of AlN ceramic is increased by nearly 10 times. The connection between the insulated gate bipolar transistor chip 4, the diode chip 5 and the ceramic direct copper-clad substrate adopts a nano-Ag solder paste low-pressure sintering process. Compared with traditional high-lead solder, the thermal conductivity of the interconnection joint is increased by more than 3 times, and the temperature resistance is not less than 200°C, which further improves the reliability of the IGBT electrical unit.

[0081] In this embodiment, the electrical connection between the front electrode of the insulated gate bipolar transistor chip 4 and the front electrode of the diode chip 5 and the surface copper clad layer of the power substrate 2 of the AlN ceramic copper clad substrate is formed by ultrasonic bonding process and aluminum bonding wire 8;

[0082] The power substrate 2 and the signal substrate 3 are bonded together via aluminum bonding wires 8 .

[0083] The power substrate 2 and the signal substrate 3 are electrically connected to the heat dissipation base plate 1 by using a vacuum brazing process and tin-lead eutectic solder.

[0084] The electrical connection between the fixed end of the signal terminal 7 and the signal substrate 3 and the electrical connection between the fixed end of the power terminal 6 and the power substrate 2 are formed by the hot air reflow process and the tin-lead eutectic solder.

[0085] Applying ultrasonic waves to the aluminum bonding wire 8 during ultrasonic bonding produces an effect similar to heating on the material's plastic deformation. The ultrasonic energy is selectively absorbed by the dislocations in the aluminum bonding wire 8, freeing them from their bound positions. This allows the aluminum bonding wire 8 to enter a plastically deformed state even with minimal external force. This deformed aluminum bonding wire 8 destroys the oxide film formed on the surface of the vapor-deposited aluminum film, exposing a clean metal surface that facilitates bonding.

[0086] The IGBT electric unit package according to another embodiment of the present invention further includes a gate resistor and a Zener diode, and the gate resistor, the Zener diode and the surface of the signal substrate 3 are electrically connected by a soldering process.

[0087] The gate-emitter or gate-source connections of the insulated gate bipolar transistor (IGBT) chip 4 and the diode chip 5 are capacitive, and parasitic inductance in the gate loop is unavoidable. Preferably, a gate resistor is connected in series to eliminate strong gate oscillations in the gate loop when stimulated by the driver's drive pulse. The gate resistor also serves to transfer power loss from the driver and reduce temperature rise. Surface gate breakdown can cause failure of the IGBT electrical unit package.

[0088] In this embodiment, a bent portion is provided at the free end of the power terminal 6 extending out of the cover plate 12 or the housing 11 , a through hole 10 is provided at the bent portion of the power terminal 6 , and a mounting base 9 with a threaded hole is provided on the cover plate 12 , the position of the mounting base 9 matches the through hole 10 .

[0089] The remaining parts of another embodiment of the present invention are the same as those of the first embodiment.

[0090] The above contents are merely examples of specific implementations of the present invention. For devices and structures not described in detail, it should be understood that they may be implemented using general devices and methods available in the art.

[0091] The above is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An IGBT electrical unit package, comprising: A heat dissipation base plate (1), a housing (11), a cover plate (12) and an IGBT electrical unit, wherein the IGBT electrical unit is welded to the upper surface of the heat dissipation base plate (1), characterized in that the lower portion of the housing (11) and the heat dissipation base plate (1) are fixedly bonded in a gas-tight manner using a sealant, and the upper portion of the housing (11) and the cover plate (12) are fixedly bonded in a gas-tight manner using a sealant; A silicone gel (14) is encapsulated in the lower portion of the accommodating cavity formed by the heat dissipation base plate (1) and the housing (11) to form a sealed structure, wherein the IGBT electrical unit is substantially contained in the silicone gel (14); An anti-deformation layer is provided on the silicone gel (14), and the anti-deformation layer is located below the cover plate (12); the anti-deformation layer is a silicone rubber layer; the ratio between the hardness of the sealing structure and the hardness of the anti-deformation layer is 1:(3-4); The sealing structure is a silicone gel (14) of 8mm-12mm provided at the lower part of the accommodating cavity formed by the heat dissipation base plate (1) and the housing (11); the anti-deformation layer is a silicone rubber (15) of 1mm-2mm provided on the silicone gel (14); a certain space is left between the anti-deformation layer and the cover plate (12); The lower portion of the housing (11) and the heat dissipation base plate (1) are fixedly bonded using epoxy glue, and the upper portion of the housing (11) and the cover plate (12) are fixedly bonded using epoxy glue.

2. The IGBT electrical unit package according to claim 1, characterized in that: The housing (11) is made of a material having a thermal expansion coefficient and a thermal expansion coefficient of the epoxy adhesive (13) in a ratio of (0.8-1.2):

1.

3. The IGBT electrical unit package according to claim 2, characterized in that: The silicone gel (14) and the silicone rubber (15) are subjected to vacuum degassing treatment.

4. The IGBT electrical unit package according to claim 2, characterized in that: The IGBT electrical unit comprises: A ceramic copper-clad substrate is welded on the heat dissipation base plate (1), wherein the ceramic copper-clad substrate comprises a power substrate (2) and a signal substrate (3) that are separated from each other, and the power substrate (2) and the signal substrate (3) are bonded and connected via metal bonding wires; an insulated gate bipolar transistor chip (4) and a diode chip (5), wherein the insulated gate bipolar transistor chip (4) and the diode chip (5) are welded on the power substrate (2) and connected by metal bonding wires; and The signal terminal (7) and the power terminal (6) are respectively welded to the ceramic copper-clad substrate using a brazing process, wherein the fixed end of the signal terminal (7) is brazed to the signal substrate (3), and the fixed end of the power terminal (6) is brazed to the power substrate (2), and the free end of the signal terminal (7) and the free end of the power terminal (6) extend from the opening of the housing (11) or the cover plate (12); The welding position of the fixed end of the power terminal (6) on the power substrate (2), the welding position of the insulated gate bipolar transistor chip (4) on the power substrate (2), and the welding position of the diode chip (5) on the power substrate (2) are separated from each other; The power substrate (2), the signal substrate (3), the insulated gate bipolar transistor chip (4), the diode chip (5), the metal bonding wires, the lower portion of the signal terminal (7) and the lower portion of the power terminal (6) of the IGBT electrical unit are contained in the silicone gel (14); The heat dissipation base plate (1) is made of a composite material containing 52%-58% by volume of AlSiC; The ceramic copper-clad substrate is an AlN ceramic copper-clad substrate; The insulated gate bipolar transistor chip (4) and the diode chip (5) are connected to the power substrate (2) of the AlN ceramic copper-clad substrate by welding using nano-Ag solder paste and a low-temperature and low-pressure welding process.

5. The IGBT electrical unit package according to claim 4, characterized in that: The back electrode of the insulated gate bipolar transistor chip (4) and the back electrode of the diode chip (5) are welded to the surface of the power substrate (2) of the AlN ceramic copper-clad substrate. During the welding process, the insulated gate bipolar transistor chip (4) and the diode chip (5) are subjected to a pressure of 5MPa-11MPa, a sintering temperature of 200°C-300°C, and a holding time of 40s-60s.

6. The IGBT electrical unit package according to claim 5, characterized in that: An ultrasonic bonding process and an aluminum bonding wire (8) are used to form an electrical connection between the front electrode of the insulated gate bipolar transistor chip (4), the front electrode of the diode chip (5), and the surface copper clad layer of the power substrate (2) of the AlN ceramic copper clad substrate; The power substrate (2) and the signal substrate (3) are bonded and connected via aluminum bonding wires (8); The power substrate (2) and the signal substrate (3) are electrically connected to the heat dissipation base plate (1) by using a vacuum brazing process and tin-lead eutectic solder; The electrical connection between the fixed end of the signal terminal (7) and the signal substrate (3) and the electrical connection between the fixed end of the power terminal (6) and the power substrate (2) are formed by a hot air reflow process and tin-lead eutectic solder.

7. The IGBT electrical unit package according to claim 6, characterized in that: It also includes a gate resistor and a voltage-stabilizing diode, and the electrical connection between the gate resistor, the voltage-stabilizing diode and the surface of the signal substrate (3) is formed by a soldering process.

8. The IGBT electrical unit package according to claim 7, characterized in that: A bent portion is provided at the free end of the power terminal (6) extending out of the cover plate (12) or the housing (11), a through hole (10) is provided at the bent portion of the power terminal (6), and a mounting base (9) with a threaded hole is provided on the cover plate (12), the position of the mounting base (9) matching the through hole (10).

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