WO2023098184A1 - 一种igbt电气单元封装件 - Google Patents

一种igbt电气单元封装件 Download PDF

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Publication number
WO2023098184A1
WO2023098184A1 PCT/CN2022/115614 CN2022115614W WO2023098184A1 WO 2023098184 A1 WO2023098184 A1 WO 2023098184A1 CN 2022115614 W CN2022115614 W CN 2022115614W WO 2023098184 A1 WO2023098184 A1 WO 2023098184A1
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Prior art keywords
substrate
igbt
electrical unit
power
chip
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PCT/CN2022/115614
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English (en)
French (fr)
Inventor
飞景明
张彬彬
李松玲
陈滔
张明华
王宁宁
曾庆晨
谭真
胡雯雯
王君
陈广军
刘丹丹
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北京卫星制造厂有限公司
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Publication of WO2023098184A1 publication Critical patent/WO2023098184A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
    • H01L23/3731—Ceramic materials or glass
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/02—Containers; Seals
    • H01L23/10—Containers; Seals characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H01L23/498—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers
    • H01L23/49811—Additional leads joined to the metallisation on the insulating substrate, e.g. pins, bumps, wires, flat leads
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
    • H01L25/18—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof the devices being of types provided for in two or more different subgroups of the same main group of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/06—Structure, shape, material or disposition of the bonding areas prior to the connecting process of a plurality of bonding areas
    • H01L2224/0601—Structure
    • H01L2224/0603—Bonding areas having different sizes, e.g. different heights or widths
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32225—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48135—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip
    • H01L2224/48137—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being arranged next to each other, e.g. on a common substrate
    • H01L2224/48139—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being arranged next to each other, e.g. on a common substrate with an intermediate bond, e.g. continuous wire daisy chain
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48225—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H01L2224/48227—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation connecting the wire to a bond pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/4847—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a wedge bond
    • H01L2224/48472—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a wedge bond the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49—Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/491—Disposition
    • H01L2224/4911—Disposition the connectors being bonded to at least one common bonding area, e.g. daisy chain
    • H01L2224/49111—Disposition the connectors being bonded to at least one common bonding area, e.g. daisy chain the connectors connecting two common bonding areas, e.g. Litz or braid wires
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73265—Layer and wire connectors

Definitions

  • the invention relates to the technical field of semiconductor packaging, in particular to an IGBT electrical unit package.
  • Insulated gate bipolar transistors insulated gate bipolar transistors, IGBTs
  • IGBTs Insulated gate bipolar transistors
  • thermal resistance is a physical concept that refers to the resistance encountered when heat flow (power) flows through a heat conductor (a temperature difference will be generated on the heat conductor).
  • the reciprocal of thermal resistance is thermal conductance.
  • good thermal conductivity of an object means small thermal resistance.
  • the thermal resistance refers to the steady-state thermal resistance from the chip to the module casing (right below the chip), called the junction-to-case thermal resistance, and is usually expressed as:
  • T j is the junction temperature of the chip
  • T c is the temperature at the specified position of the module shell
  • P is the dissipated power
  • the IGBT module packaging structure has low reliability in a low-voltage environment, and the IGBT module packaging structure in the prior art has a large junction-to-case thermal resistance, which also has an adverse effect on reliability.
  • the present invention aims at the above-mentioned problems in the prior art, and provides an IGBT electrical unit package with small junction-to-case thermal resistance and high reliability, which is applicable to low-voltage operating environments.
  • 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, the IGBT electrical unit is welded on the upper surface of the heat dissipation base plate, between the lower part of the housing and the heat dissipation base plate A sealant is used for gas-tight bonding, and a sealant is used for gas-tight bonding between the upper part of the casing and the cover plate.
  • the lower part of the accommodating cavity formed by the heat dissipation bottom plate and the housing is potted with silicone gel to form a sealed structure, and the IGBT electrical unit is basically contained in the silicone gel.
  • An anti-deformation layer is arranged on the silicone gel, and the anti-deformation layer is located under the cover plate.
  • the IGBT electrical unit welded on the heat dissipation base plate is basically contained in the sealing structure formed by the silicone gel, so that the IGBT electrical unit is in an airtight sealing structure as a whole, because there is no gas in the sealing structure, making the IGBT electrical unit
  • the inside of the unit can not be affected by the external low pressure environment.
  • the welding place between the internal terminal of the IGBT electrical unit and the heat dissipation bottom plate the welding place between the housing and the heat dissipation bottom plate, the welding place between the ceramic copper-clad substrate and the insulated gate bipolar transistor chip and the diode chip
  • the gas in the tiny enclosed space formed by the tiny gaps will not escape into the silicone gel.
  • the silicone gel includes ceramic copper-clad substrate, the insulated gate bipolar transistor chip and the diode chip and includes all metal bonding wires, and the anti-deformation layer is arranged on the silicone gel.
  • a certain amount of power must be applied during operation, and most of this power is converted into heat, which causes the temperature rise of the device chip.
  • the heat of the insulated gate bipolar transistor chip and the diode chip on the IGBT electrical unit is transferred to the casing through welding and sintering materials, and further transferred to the surrounding air environment. This energy is also transferred to the silicone gel. Silicone gel is affected by temperature and thus expands in volume.
  • the external pressure of the silicone gel is greatly reduced compared with the normal environment of 1 atmosphere, which will also cause the volume of the softer silicone gel to expand.
  • the harder anti-deformation layer has a certain mechanical pressing effect, which can effectively prevent the deformation of the silicone gel caused by air pressure and heat.
  • epoxy glue is used to fix and bond the lower part of the housing to the heat dissipation bottom plate, and epoxy glue is used to fix and bond the upper part of the housing to the cover plate;
  • the anti-deformation layer is a silicone rubber layer. Silicon rubber can be used at 150 to minus 350 degrees. It still has good elasticity and good chemical stability at minus 60 to minus 70 degrees. Therefore, it is made of silicone rubber.
  • the formed anti-deformation layer can be used at a higher working temperature without changes in shape and properties.
  • Epoxy glue has high strength, good toughness, excellent point insulation, can be used for a long time in the range of minus 80° to 200°, has good chemical stability, small shrinkage after curing and strong bonding ability.
  • the heat dissipation bottom plate and the shell are bonded together by epoxy glue, and the anti-deformation layer, together with the heat dissipation bottom plate and the shell, restricts the volume stability of the silicone gel at high temperature and low air pressure, thereby ensuring that it is packaged in the anti-deformation layer and the heat dissipation bottom plate And the reliability of the IGBT electrical unit inside the shell in use.
  • the ratio between the hardness of the sealing structure and the hardness of the anti-deformation layer is 1:(3-4).
  • the size of the hardness is related to the change of the extrusion strength.
  • the silicone gel with low hardness is slightly weaker in force, and the silicone rubber with high hardness has high extrusion strength.
  • the hardness of the silicone rubber layer of the anti-deformation layer is greater than that of the silicone gel. The softer silicone gel will not exert compressive stress on the metal bonding wire and can protect the bonding wire.
  • the housing is made of a material whose ratio of thermal expansion coefficient to epoxy glue is (0.8-1.2):1;
  • the shell made of a material having a similar thermal expansion coefficient to the epoxy glue will expand together with the volume of the cured epoxy glue when heated, so as to avoid a gap between the epoxy glue and the shell at a higher working temperature.
  • the sealing structure is an 8mm-12mm silicone gel set at the lower part of the accommodating cavity formed by the heat dissipation bottom plate and the housing, and the anti-deformation layer is formed on the silicon gel 1mm-2mm silicone rubber is set on the glue, wherein the silicone gel and the silicone rubber are subjected to vacuum defoaming treatment.
  • the thickness of the silicone gel ranges from 8mm to 12mm, which can effectively protect the ceramic copper-clad substrate, the IGBT chip, the diode chip and all metal bonding wires to avoid the leakage of the lead wires. Problems such as insufficient pressure resistance; the silicone rubber of the anti-deformation layer is set on the silicone gel.
  • the thickness of silicone rubber is 1-2mm.
  • the appropriate thickness has high hardness, which can effectively prevent the bubble precipitation of silicone gel in a low-pressure environment, and also leave a certain space between the anti-deformation layer and the cover plate to prevent Thermal expansion of the silicone rubber and silicone gel squeezes the cover and housing.
  • Silicone rubber and silicone gel have undergone vacuum defoaming treatment to eliminate micro-bubbles.
  • IGBT electrical units are used in low-voltage environments, although there is a pressure difference between the inside and outside of the IGBT electrical units, there will be no partial discharge of micro-bubbles under the action of high-voltage electric fields. , will not cause the aging decomposition of the organic insulating potting body, and improve the reliability of the IGBT electrical unit package.
  • the IGBT electrical unit includes:
  • the ceramic copper-clad substrate is welded on the heat dissipation base plate, wherein the ceramic copper-clad substrate includes a power substrate and a signal substrate that are separated from each other, and the power substrate and the signal substrate are connected by metal bonding wire bonding ;
  • an insulated gate bipolar transistor chip and a diode chip the insulated gate bipolar transistor chip and the diode chip are welded on the power substrate and connected by metal bonding wire bonding;
  • the signal terminals and the power terminals are respectively welded on the ceramic copper-clad substrate using a brazing process, wherein the fixed ends of the signal terminals are brazed and connected to the signal substrate, and the fixed ends of the power terminals are connected by brazing On the power substrate, the free ends of the signal terminals and the free ends of the power terminals protrude from the openings of the housing or the cover plate;
  • the welding position of the fixed end of the power terminal on the power substrate, the welding position of the IGBT chip on the power substrate, and the welding position of the diode chip on the power substrate separated from each other;
  • the power substrate, the signal substrate, the insulated gate bipolar transistor chip, the diode chip, the metal bonding wire, the lower part of the signal terminal and the lower part of the power terminal of the IGBT electric unit are contained in the silicon inside the gel;
  • the heat dissipation bottom plate is made of a composite material containing 52%-58% volume fraction of AlSiC;
  • the ceramic copper-clad substrate is an AlN ceramic copper-clad substrate
  • the insulated gate bipolar transistor chip and the diode chip are welded and connected to the power substrate of the AlN ceramic copper-clad substrate using nano-Ag solder paste and a low-temperature and low-pressure welding process.
  • the heat dissipation bottom plate is made of AlSiC composite material with a volume fraction of 52%-58%. Compared with the traditional bottom plate, the density is reduced from 7.8g/cm 3 to 2.99 g/cm 3 , and the weight of the module is greatly reduced under the same volume.
  • the back electrode of the insulated gate bipolar transistor chip and the back electrode of the diode chip are soldered to the surface of the power substrate of the AlN ceramic copper-clad substrate, and the insulating The gate bipolar transistor chip and the diode chip are subjected to a pressure of 5MPa-11MPa during the welding process, the sintering temperature is 200°C-300°C, and the holding time is 40s-60s.
  • AlN ceramic direct copper clad substrate compared with the traditional alumina ceramic copper clad substrate, the thermal conductivity of AlN ceramic is increased by nearly 10 times, and the connection between the insulated gate bipolar transistor chip, the diode chip and the ceramic direct copper clad substrate Using 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 lower than 200°C, which further improves the reliability of the IGBT electrical unit.
  • the front electrode of the insulated gate bipolar transistor chip and the front electrode of the diode chip and the power electrode of the AlN ceramic copper-clad substrate are formed by an ultrasonic bonding process and an aluminum bonding wire.
  • the power substrate and the signal substrate are connected by aluminum bonding wire bonding.
  • the electric connection between the power substrate and the signal substrate and the heat dissipation bottom plate is formed by a vacuum soldering process and tin-lead eutectic solder.
  • 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 hot air reflow soldering process and tin-lead eutectic solder.
  • Ultrasonic waves are applied to aluminum bonding wires using the ultrasonic bonding process, which has an effect on the plastic deformation of the material, similar to heating.
  • the ultrasonic energy is selectively absorbed by the dislocations in the aluminum bonding wire, so that the dislocations are released at the bound position, so that the aluminum bonding wire can be in a plastic deformation state under a very low external force.
  • the aluminum bonding wire deformed in this state can destroy the oxide film formed on the surface of the aluminum film in the evaporated state, exposing a clean metal surface, which is beneficial to the bonding operation.
  • a gate resistor and a Zener diode are further included, and the electrical connection between the gate resistor, the Zener diode and the surface of the signal substrate is formed by a soldering process.
  • Insulated gate bipolar transistor chips and diode chips have a capacitive structure between the gate-emitter or the gate-source, and the parasitic inductance of the gate loop is unavoidable.
  • a gate resistor is connected in series to eliminate the strong gate oscillation generated by the gate loop under the excitation of the drive pulse of the driver. At the same time, the gate resistor can transfer the power loss of the driver and reduce the temperature rise. Surface gate breakdown causes IGBT electrical unit package failure.
  • the free end of the power terminal protruding from the cover or the housing is provided with a bent part, and a through hole is provided at the bent part of the power terminal, and a mounting hole with a threaded hole is provided on the cover plate.
  • the base, the position of the installation base matches the through hole.
  • the IGBT electrical unit package of the present invention can especially meet the higher requirements for the reliability, weight and other indicators of the IGBT electrical unit package in a relatively high working temperature environment by reducing the package thermal resistance of the IGBT module.
  • the IGBT electrical unit package of the present invention adopts AlN ceramic direct copper-clad substrate, compared with the traditional aluminum oxide ceramic copper-clad substrate, the thermal conductivity of AlN ceramic is improved by nearly 10 times, and the insulated gate bipolar transistor chip, diode chip and The low-pressure sintering process of nano-Ag solder paste is used for the connection between the ceramic direct copper-clad substrates. Compared with the traditional high-lead solder, the thermal conductivity of the interconnection joint is increased by more than 3 times, and the temperature resistance is not lower than 200°C, making the IGBT electrical The reliability of the unit package is further improved in the environment of higher operating temperature.
  • the IGBT electrical unit package in the present invention adopts a highly airtight package structure to ensure that when the IGBT electrical unit package is installed in a high-altitude application scene such as an aircraft, the IGBT electrical unit package will not be damaged due to air pressure reduction. When the internal withstand voltage capacity is reduced, the reliability of the IGBT electrical unit package is guaranteed.
  • Fig. 1 is the structural representation of the IGBT electrical unit of an embodiment of the present invention
  • Fig. 2 is the perspective view of the IGBT electrical unit package of an embodiment of the present invention.
  • Fig. 3 is the layout structure diagram of the ceramic copper-clad substrate of the IGBT electric unit of an embodiment of the present invention.
  • Fig. 4 is a schematic structural view of an IGBT electrical unit package according to an embodiment of the present invention.
  • Drawing number 1-radiation bottom plate; 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-installation base; 10-through hole; 11-shell; 12-cover plate; 13-epoxy glue; 14-silicone gel;
  • the IGBT electric unit package of an embodiment of the present invention comprises: heat dissipation bottom plate 1, shell 11, cover plate 12 and IGBT electric unit, IGBT electric unit is welded on heat dissipation bottom plate 1
  • the upper surface, the lower part of the casing 11 and the heat dissipation bottom plate 1 are fixed and bonded in a gas-tight manner with a sealant, and the upper part of the casing 11 and the cover plate 12 are fixed and bonded in a gas-tight manner with a sealant;
  • Silicone gel 14 is potted in the lower part of the accommodating cavity formed by the heat dissipation bottom plate 1 and the housing 11 to form a sealed structure, and the IGBT electrical unit is basically contained in the silicone gel 14;
  • An anti-deformation layer is provided on the silicone gel 14 , and the anti-deformation layer is located under the cover plate 12 .
  • the IGBT electrical unit welded on the heat dissipation base plate 1 is basically contained in the sealing structure formed by the silicone gel 14, so that the IGBT electrical unit is in an airtight sealing structure as a whole, because there is no gas in the sealing structure, making the IGBT electrical unit
  • the inside of the unit can not be affected by the external low pressure environment.
  • the welding position between the housing 11 and the heat dissipation base plate 1, and the welding position between the ceramic copper-clad substrate and the insulated gate bipolar transistor chip 4 and the diode chip 5 The gas in the tiny enclosed space formed by the tiny gaps will not escape into the silicone gel 14 .
  • the silicone gel 14 includes a ceramic copper-clad substrate, an IGBT chip 4 and a diode chip 5 and includes all metal bonding wires, and the anti-deformation layer is disposed on the silicone gel 14 .
  • a certain amount of power must be applied during operation, and most of this power is converted into heat, which causes the temperature rise of the device chip.
  • the heat of the insulated gate bipolar transistor chip 4 and the diode chip 5 on the IGBT electrical unit is transferred to the casing 11 through welding and sintering materials, and further transferred to the surrounding air environment. This part of energy is also transferred to the silicone gel 14 .
  • the silicone gel 14 is affected by temperature and then expands in volume.
  • the external pressure of the silicone gel 14 is greatly reduced compared with the normal environment of 1 atmosphere, which will also cause the softer silicone gel 14 to expand in volume.
  • the harder anti-deformation layer has a certain mechanical pressing effect, which can effectively prevent the deformation of the silicone gel 14 caused by air pressure and heat.
  • the lower part of the housing 11 and the heat dissipation bottom plate 1 are fixed and bonded with epoxy glue, and the upper part of the housing 11 and the cover plate 12 are fixed and bonded with epoxy glue;
  • the anti-deformation layer is a silicone rubber layer
  • Epoxy glue 13 has high strength, good toughness, excellent point insulation, can be used for a long time in the range of minus 80° to 200°, has good chemical stability, small shrinkage after curing and strong bonding ability.
  • the heat dissipation bottom plate 1 and the shell 11 are bonded together by epoxy glue 13, and the anti-deformation layer together with the heat dissipation bottom plate 1 and the shell 11 restricts the volume stability of the silicone gel 14 at a higher temperature and a lower air pressure, thereby ensuring that the package is in The anti-deformation layer and the reliability of the heat dissipation bottom plate 1 and the IGBT electric unit inside the casing 11 in use.
  • the ratio between the hardness of the sealing structure and the hardness of the anti-deformation layer is 1:3.
  • the magnitude of the hardness is related to the change of the extrusion strength, the silicone gel 14 with low hardness is slightly weaker in strength, and the silicone rubber 15 with high hardness has high extrusion strength. Specifically, the hardness of the silicone rubber 15 of the anti-deformation layer is greater than that of the silicone gel 14 . The softer silicone gel 14 will not produce compressive stress on the metal bonding wires and can protect the bonding wires.
  • the housing 11 is made of epoxy resin
  • the shell 11 made of epoxy resin having the same coefficient of thermal expansion as the epoxy glue 13 will expand together with the volume of the cured epoxy glue 13 when heated, which can avoid the contact between the epoxy glue 13 and the epoxy glue 13 at a higher working temperature.
  • a gap is created between the casings 11 .
  • the sealing structure is an 8mm-12mm silicone gel 14 arranged at the bottom of the accommodating cavity formed by the heat dissipation bottom plate 1 and the housing 11, and the anti-deformation layer is a 1mm-2mm silicone gel 14 arranged on the silicone gel 14.
  • Silicone rubber 15 and silicone gel 14 have undergone vacuum degassing treatment to eliminate micro-bubbles.
  • IGBT electrical units in low-voltage environments, although there is a pressure difference between the inside and outside of the IGBT electrical units, there will be no local micro-bubbles under the action of high-voltage electric fields.
  • the discharge phenomenon does not cause aging and decomposition of the organic insulating potting body, and improves the reliability of the IGBT electrical unit package.
  • the thickness range of the silicone gel 14 is 8mm-12mm, which can effectively protect the power substrate 2, the signal substrate 3, the insulated gate bipolar transistor chip 4, the diode chip 5 and all the metal bonding wires 8 of the ceramic copper-clad substrate.
  • the silicone rubber 15 of the anti-deformation layer is arranged on the silicone gel 14.
  • the thickness of the silicone rubber 15 is 1mm-2mm, and the appropriate thickness has high hardness, which can effectively prevent the bubble precipitation of the silicone gel 14 in a low-pressure environment, and also leave a certain amount of space between the anti-deformation layer and the cover plate 12. The space prevents the thermal expansion of the silicone rubber 15 and the silicone gel 14 from pressing the cover plate 12 and the casing 11 .
  • the IGBT electrical unit includes:
  • the 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 and connected by aluminum bonding wires 8;
  • the insulated gate bipolar transistor chip 4, the diode chip 5, the insulated gate bipolar transistor chip 4 and the diode chip 5 are welded on the power substrate 2, and are bonded and connected by aluminum bonding wires 8; and
  • the signal terminal 7 and the power terminal 6 are respectively welded on the ceramic copper-clad substrate using a brazing process, wherein the fixed end of the signal terminal 7 is brazed and connected to the signal substrate 3, and the fixed end of the power terminal 6 is connected to the power substrate by brazing 2, the free end of the signal terminal 7 and the free end of the power terminal 6 protrude from the opening of the casing 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 IGBT 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 aluminum bonding wire 8, the lower part of the signal terminal 7 and the lower part of the power terminal 6 of the IGBT electrical unit are contained in the silicone gel 14;
  • the heat dissipation bottom plate 1 is made of a composite material containing 55% volume fraction 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 welded and connected to the power substrate 2 of the AlN ceramic copper-clad substrate using nano-Ag solder paste and a low-temperature and low-pressure welding process.
  • the IGBT electrical unit in this embodiment is a half-bridge IGBT electrical unit.
  • the heat dissipation bottom plate 1 is made of AlSiC composite material with a volume fraction of 55%. Compared with the traditional bottom plate, the density is reduced from 7.8g/cm3 to 2.99 g/cm3, and the weight of the module is greatly reduced under the same volume.
  • the back electrode of the insulated gate bipolar transistor chip 4 and the back electrode of the diode chip 5 are soldered and connected to the surface of the power substrate 2 of the AlN ceramic copper-clad substrate, and the insulated gate bipolar transistor chip 4 and the The diode chip 5 is subjected to 8MPa pressure during the welding process, the sintering temperature is 250°C, and the holding time is 50s.
  • AlN ceramic direct copper clad substrate Compared with the traditional aluminum oxide ceramic copper clad substrate, the thermal conductivity of AlN ceramic is increased by nearly 10 times, the insulated gate bipolar transistor chip 4, diode chip 5 and ceramic direct copper clad substrate
  • the interconnection adopts the low-pressure sintering process of nano-Ag solder paste. Compared with the traditional high-lead solder, the thermal conductivity of the interconnection joint is increased by more than 3 times, and the temperature resistance is not lower than 200°C, which further improves the reliability of the IGBT electrical unit. .
  • the front electrode of the insulated gate bipolar transistor chip 4 and the front electrode of the diode chip 5 are formed by the ultrasonic bonding process and the aluminum bonding wire 8, and the surface electrode of the power substrate 2 of the AlN ceramic copper-clad substrate is covered with copper. Electrical connections between layers;
  • the power substrate 2 and the signal substrate 3 are bonded and connected by aluminum bonding wires 8 .
  • the electrical connection between the power substrate 2 and the signal substrate 3 and the heat dissipation bottom plate 1 is formed by a vacuum soldering 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 hot air reflow soldering process and tin-lead eutectic solder.
  • Applying ultrasonic waves to the aluminum bonding wire 8 by using the ultrasonic bonding process has an effect on the plastic deformation of the material, which is similar to heating.
  • the ultrasonic energy is selectively absorbed by the dislocations in the aluminum bonding wires 8 , so that the dislocations are released at the bound positions, so that the aluminum bonding wires 8 can be in a plastic deformation state under very low external force.
  • the aluminum bonding wire 8 deformed in this state can destroy the oxide film formed on the surface of the aluminum film in the evaporated state, exposing a clean metal surface, which is beneficial to the bonding operation.
  • the IGBT electrical unit package according to another embodiment of the present invention further includes a gate resistor and a Zener diode, and the electrical connection between the gate resistor, the Zener diode and the surface of the signal substrate 3 is formed by a soldering process.
  • a gate resistor is connected in series to eliminate the strong gate oscillation generated by the gate loop under the excitation of the drive pulse of the driver. At the same time, the gate resistor can transfer the power loss of the driver and reduce the temperature rise. Surface gate breakdown causes IGBT electrical unit package failure.
  • the free end of the power terminal 6 protruding from the cover plate 12 or housing 11 is provided with a bent portion, and a through hole 10 is provided at the bent portion of the power terminal 6, and a mounting base with a threaded hole is provided on the cover plate 12. seat 9, the position of the mounting base 9 matches the through hole 10.

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Abstract

本发明属于半导体封装技术领域，提供一种IGBT电气单元封装件。本发明提供的IGBT电气单元封装件包括：散热底板（1）、外壳（11）、盖板（12）和IGBT电气单元，本发明中散热底板采用52％‑58％体积分数的AlSiC复合材料，IGBT电气单元封装件采用AlN陶瓷直接覆铜基板，绝缘栅双极型晶体管芯片（4）、二极管芯片（5）与陶瓷直接覆铜基板之间连接采用纳米Ag焊膏低压烧结工艺。本发明中的IGBT电气单元封装件采用具有高气密性的封装结构，保证该IGBT电气单元封装件在高海拔应用场景时，不会发生由于气压降低导致IGBT电气单元封装件内部耐压能力下降的情况，保证IGBT电气单元封装件的可靠性。

Description

一种IGBT电气单元封装件
本申请要求于2021年11月30日提交中国专利局、申请号为202111442707.4、申请名称为“一种IGBT电气单元封装件”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及半导体封装技术领域，尤其涉及一种IGBT电气单元封装件。
 背景技术
[根据细则26改正14.11.2022]　
绝缘栅双极型晶体管（insulated gate bipolar transistor，IGBT）凭借其功耗小、驱动简单、载流密度大，饱和压降低等许多优点，已成为电力电子系统的核心部件之一，广泛应用于电动汽车、新能源发电、智能电网、轨道交通、高压输电等诸多关键领域；同时也是电机驱动系统和伺服系统中的重要部件，其质量与可靠性对装备运行具有重要意义。
对于半导体器件来讲，在工作的时候要施加一定的功率(特别是功率器件)，这一功率的绝大部分被转换为热量，并导致器件芯片的温升。芯片上的热量通过芯片烧结材料传递到外壳，并进一步传递到周围的空气环境(对功率器件有时还要通过散热器)。热阻是一个物理学概念，指的是热流(功率)流过导热体时所受到的阻力(会在导热体上产生温差)。热阻的倒数就是热导，通俗地讲，物体导热性能好就是热阻小。
对于大功率模块，热阻指的是从芯片到模块外壳(芯片正下方)的稳态热阻，称为结壳热阻，通常表示为：
                          
Figure dest_path_image001
式中T j为芯片结温，T c为模块外壳制定位置温度，P为耗散功率。
随着IGBT模块电压等级的提升、开关频率的提高，致使开关管的损耗也不断上升，模块内部的发热量也越来越高。IGBT模块的工作特性受温度影响较大，半导体物理常数与器件内部参数都会随温度的变化而改变，从而导致IGBT模块的开通、关断速度、通态压降等性能指标发生变化。现有技术中， IGBT模块封装结构在低压环境中可靠性较低，现有技术中的IGBT模块封装结构结壳热阻较大、对可靠性也有不利影响。
 技术问题
本发明针对现有技术存在的上述问题，提供了一种具有较小结壳热阻，较高可靠性的能够适用于低压使用环境的IGBT电气单元封装件。
 技术解决方案
本发明提供的IGBT电气单元封装件包括：散热底板、外壳、盖板和IGBT电气单元，所述IGBT电气单元焊接于所述散热底板的上表面，所述外壳的下部和所述散热底板之间使用密封胶气体密封地固定粘接，所述外壳的上部与所述盖板之间使用密封胶气体密封地固定粘接。
在所述散热底板和所述外壳形成的容置腔体的下部灌封硅凝胶，以形成密封结构，所述IGBT电气单元基本包含在所述硅凝胶内。
在所述硅凝胶上设置防形变层，所述防形变层位于所述盖板的下方。
在散热底板上焊接的IGBT电气单元基本被包含在所述硅凝胶形成的密封结构中，使IGBT电气单元处于整体具有气密性的密封结构中，因为密封结构中不存在气体，使得IGBT电气单元内部能够不受外界低压环境影响。在低压环境下，在IGBT电气单元内部端子与散热底板的焊接处、外壳与散热底板的焊接处，所述陶瓷覆铜基板与所述绝缘栅双极型晶体管芯片和所述二极管芯片的焊接处的微小缝隙形成的微小密闭空间中的气体不会逸出至硅凝胶内。
硅凝胶包含陶瓷覆铜基板与所述绝缘栅双极型晶体管芯片和所述二极管芯片且包含住全部的金属键合丝，防形变层设置在硅凝胶上。对于半导体器件来讲，在工作的时候要施加一定的功率，这一功率的绝大部分被转换为热量，并导致器件芯片的温升。IGBT电气单元上所述绝缘栅双极型晶体管芯片和所述二极管芯片的热量通过焊接烧结材料传递到外壳，并进一步传递到周围的空气环境。这部分能量也会传递至硅凝胶。硅凝胶受到温度的影响进而产生体积膨胀。在低压环境下，硅凝胶受到的外界气压较于在正常1个大气压的环境中大幅降低，也会导致较软的硅凝胶体积膨胀。而较硬的防变形层具有一定的机械压制作用，能够有效防止硅凝胶因气压和受热引起的变形。
根据本发明的一个方面，所述外壳的下部和所述散热底板之间使用环氧胶固定粘接，所述外壳的上部与所述盖板之间使用环氧胶固定粘接；
所述防形变层是硅橡胶层，硅橡胶可在150度至零下350度下使用，在零下60度至零下70度时仍具有较好的弹性，化学稳定性较好，所以以硅橡胶制成的防形变层能够在较高工作温度下使用不会发生形状与性质的改变。
环氧胶强度较高，韧性较好，点绝缘性优良，可在零下80°至200°范围内长期使用，化学稳定性较好，固化成型后收缩率小，粘接能力强。散热底板与外壳通过环氧胶粘接成一体，防形变层与散热底板和外壳一同限制硅凝胶在较高温度、较低气压下保持体积的稳定，进而保证封装在防形变层与散热底板和外壳内部的IGBT电气单元在使用中的可靠性。
根据本发明的一个方面，所述密封结构的硬度和所述防形变层的硬度之间的比例为1:（3-4）。
硬度的大小与挤压强度的变化有关，低硬度的硅凝胶在受力度上稍差，高硬度的硅橡胶具有高挤压强度。具体地，防形变层的硅橡胶层硬度大于硅凝胶的硬度。较软的硅凝胶对金属键合丝不会产生压应力且能够保护键合金属丝。
根据本发明的一个方面，所述外壳由热膨胀系数与环氧胶的热膨胀系数之比为（0.8-1.2）：1的材料制成；
优选地，与环氧胶具有相近热膨胀系数的材料制成的外壳，在受热时会与固化的环氧胶体积一同膨胀，能够避免在较高工作温度下环氧胶与外壳之间产生间隙。
根据本发明的一个方面，所述密封结构是在所述散热底板和所述外壳形成的容置腔体的下部设置的8mm-12mm的硅凝胶，所述防形变层是在所述硅凝胶上设置的1mm-2mm的硅橡胶，其中，所述硅凝胶和所述硅橡胶经过真空脱泡处理。
硅凝胶厚度范围在8mm-12mm，能有效的将所述陶瓷覆铜基板、所述绝缘栅双极型晶体管芯片、所述二极管芯片和全部的金属键合丝保护在内，避免引线漏出造成耐压不足等问题；防形变层的硅橡胶设置在硅凝胶上。硅橡胶厚度1-2mm，适宜的厚度具有较高的硬度，能有效防止硅凝胶在低气压环境下发生气泡析出的问题，同时也在防形变层与盖板之间留出一定空间，防止硅橡胶和硅凝胶发生的热膨胀挤压盖板和外壳。
硅橡胶、硅凝胶经过真空脱泡处理，消除了微气泡，在低压环境应用IGBT电气单元时，虽然IGBT电气单元内外存在气压差，也不会出现微气泡在高压电场作用下的局部放电现象，不会造成有机绝缘的灌封体的老化分解，提高了IGBT电气单元封装件的可靠性。
根据本发明的一个方面，所述IGBT电气单元包括：
陶瓷覆铜基板，焊接在所述散热底板上,其中，所述陶瓷覆铜基板包括相互分离的功率基板和信号基板，所述功率基板和所述信号基板之间通过金属键合线键合连接；
绝缘栅双极型晶体管芯片、二极管芯片，所述绝缘栅双极型晶体管芯片和所述二极管芯片焊接在所述功率基板上，通过金属键合线键合连接；和
信号端子、功率端子，分别使用钎焊工艺焊接在所述陶瓷覆铜基板上，其中，所述信号端子的固定端钎焊连接到所述信号基板上，所述功率端子的固定端钎焊连接到所述功率基板上，所述信号端子的自由端、所述功率端子的自由端由所述外壳或所述盖板的开口处伸出；
所述功率端子的固定端在所述功率基板上的焊接位置、所述绝缘栅双极型晶体管芯片在所述功率基板上的焊接位置和所述二极管芯片焊接在所述功率基板上的焊接位置相互分离；
所述IGBT电气单元的所述功率基板、所述信号基板、绝缘栅双极型晶体管芯片、二极管芯片、金属键合线、所述信号端子的下部和所述功率端子的下部包含在所述硅凝胶内；
所述散热底板由含有52%-58%体积分数的AlSiC的复合材料制成；
所述陶瓷覆铜基板为AlN陶瓷覆铜基板；
所述绝缘栅双极型晶体管芯片和所述二极管芯片与所述AlN陶瓷覆铜基板的所述功率基板之间使用纳米Ag焊膏、使用低温低压焊接工艺焊接连接。
本发明中散热底板采用52%-58%体积分数的AlSiC复合材料，相比于传统底板，密度由7.8g/cm 3下降到2.99 g/cm 3，相同体积下模块重量大幅度下降。
根据本发明的一个方面，所述绝缘栅双极型晶体管芯片的背面电极和所述二极管芯片的背面电极与所述AlN陶瓷覆铜基板的所述功率基板的表面之间焊接连接，所述绝缘栅双极型晶体管芯片和所述二极管芯片在焊接过程中受到5MPa-11MPa压力，烧结温度200℃-300℃，保温时间40s-60s。
采用AlN陶瓷直接覆铜基板，相比于传统的氧化铝陶瓷覆铜基板，AlN陶瓷热导率提升了近10倍，绝缘栅双极型晶体管芯片、二极管芯片与陶瓷直接覆铜基板之间连接采用纳米Ag焊膏低压烧结工艺，相比于传统高铅钎料，互连接头热导率提升了3倍多，耐温度能力不低于200℃，使IGBT电气单元的可靠性进一步提升。
根据本发明的一个方面，由超声键合工艺和铝键合线形成所述绝缘栅双极型晶体管芯片的正面电极和所述二极管芯片的正面电极与所述AlN陶瓷覆铜基板的所述功率基板的表面覆铜层之间的电连接；
所述功率基板和所述信号基板之间通过铝键合线键合连接。
由真空钎焊工艺和锡铅共晶焊料，形成所述功率基板和所述信号基板与所述散热底板的电连接。
由热风回流焊工艺和锡铅共晶焊料，形成所述信号端子的固定端与所述信号基板的电连接，及所述功率端子的固定端与所述功率基板的电连接。
使用超声键合工艺对铝键合线施加超声波，对材料的塑性变形产生的影响，类似于加热。超声波能量被铝键合线中的位错选择性吸收，从而位错在束缚位置解脱出来，致使铝键合线在很低的外力下即可处于塑性变形状态。在这种状态下变形的铝键合线，可以使处在蒸镀状态下的铝膜表面形成的氧化膜破坏，露出清洁的金属表面，利于键合操作。
根据本发明的一个方面，还包括栅极电阻和稳压二极管，由钎焊工艺形成所述栅极电阻、所述稳压二极管与所述信号基板的表面的电连接。
绝缘栅双极型晶体管芯片、二极管芯片的栅射或栅源极之间是容性结构，栅极回路的寄生电感又是不可避免的。优选地，串联一个栅极电阻消除栅极回路在驱动器驱动脉冲的激励下要产生很强的栅极振荡。 同时栅极电阻可以起到转移驱动器的功率损耗，降低温升的作用。表面栅极击穿造成IGBT电气单元封装件失效。
根据本发明的一个方面，所述功率端子伸出盖板或外壳的自由端设置折弯部，在所述功率端子的折弯部设置通孔，所述盖板上设置带有螺纹孔的安装基座，所述安装基座的位置与所述通孔相匹配。
 有益效果
本发明的IGBT电气单元封装件在通过降低IGBT模块的封装热阻，尤其能够满足在较高工作温度环境下对IGBT电气单元封装件的可靠性、重量等指标的更高要求。
本发明的IGBT电气单元封装件采用AlN陶瓷直接覆铜基板，相比于传统的氧化铝陶瓷覆铜基板，AlN陶瓷热导率提升了近10倍，绝缘栅双极型晶体管芯片、二极管芯片与陶瓷直接覆铜基板之间连接采用纳米Ag焊膏低压烧结工艺，相比于传统高铅钎料，互连接头热导率提升了3倍多，耐温度能力不低于200℃，使IGBT电气单元封装件在较高工作温度的环境下的可靠性进一步提升。本发明中的IGBT电气单元封装件采用具有高气密性的封装结构，保证该IGBT电气单元封装件在高海拔应用场景如安装在飞机上时，不会发生由于气压降低导致IGBT电气单元封装件内部耐压能力下降的情况，保证IGBT电气单元封装件的可靠性。
 附图说明
图1是本发明的一个实施例的IGBT电气单元的结构示意图；
图2是本发明的一个实施例的IGBT电气单元封装件的立体图；
图3是本发明的一个实施例的IGBT电气单元的陶瓷覆铜基板排布结构图；
图4是本发明的一个实施例的IGBT电气单元封装件的结构示意图。
附图编号：1-散热底板；2-功率基板；3-信号基板；4-绝缘栅双极型晶体管芯片；5-二极管芯片；6-功率端子；7-信号端子；8-铝键合线；9-安装基座；10-通孔；11-外壳；12-盖板；13-环氧胶；14-硅凝胶；15-硅橡胶。
 本发明的实施方式
为了更清楚地说明本发明实施方式或现有技术中的技术方案，下面将对实施方式中所需要使用的附图作简单地介绍。显而易见地，下面描述中的附图仅仅是本发明的一些实施方式，对于本领域普通技术人员而言，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
下面结合附图和具体实施方式对本发明作详细地描述，实施方式不能在此一一赘述，但本发明的实施方式并不因此限定于以下实施方式。
如图1、图2和图4所示，本发明的一个实施例的IGBT电气单元封装件包括：散热底板1、外壳11、盖板12和IGBT电气单元，IGBT电气单元焊接于散热底板1的上表面，外壳11的下部和散热底板1之间使用密封胶气体密封地固定粘接，外壳11的上部与盖板12之间使用密封胶气体密封地固定粘接；
在散热底板1和外壳11形成的容置腔体的下部灌封硅凝胶14，以形成密封结构，IGBT电气单元基本包含在硅凝胶14内；
在硅凝胶14上设置防形变层，防形变层位于盖板12的下方。
在散热底板1上焊接的IGBT电气单元基本被包含在硅凝胶14形成的密封结构中，使IGBT电气单元处于整体具有气密性的密封结构中，因为密封结构中不存在气体，使得IGBT电气单元内部能够不受外界低压环境影响。在低压环境下，在IGBT电气单元内部端子与散热底板1的焊接处、外壳11与散热底板1的焊接处，陶瓷覆铜基板与绝缘栅双极型晶体管芯片4和二极管芯片5的焊接处的微小缝隙形成的微小密闭空间中的气体不会逸出至硅凝胶14内。
硅凝胶14包含陶瓷覆铜基板与绝缘栅双极型晶体管芯片4和二极管芯片5且包含住全部的金属键合丝，防形变层设置在硅凝胶14上。对于半导体器件来讲，在工作的时候要施加一定的功率，这一功率的绝大部分被转换为热量，并导致器件芯片的温升。IGBT电气单元上绝缘栅双极型晶体管芯片4和二极管芯片5的热量通过焊接烧结材料传递到外壳11，并进一步传递到周围的空气环境。这部分能量也会传递至硅凝胶14。硅凝胶14受到温度的影响进而产生体积膨胀。在低压环境下，硅凝胶14受到的外界气压较于在正常1个大气压的环境中大幅降低，也会导致较软的硅凝胶14体积膨胀。而较硬的防变形层具有一定的机械压制作用，能够有效防止硅凝胶14因气压和受热引起的变形。
在该实施例中，外壳11的下部和散热底板1之间使用环氧胶固定粘接，外壳11的上部与盖板12之间使用环氧胶固定粘接；
防形变层是硅橡胶层；
环氧胶13强度较高，韧性较好，点绝缘性优良，可在零下80°至200°范围内长期使用，化学稳定性较好，固化成型后收缩率小，粘接能力强。散热底板1与外壳11通过环氧胶13粘接成一体，防形变层与散热底板1和外壳11一同限制硅凝胶14在较高温度、较低气压下保持体积的稳定，进而保证封装在防形变层与散热底板1和外壳11内部的IGBT电气单元在使用中的可靠性。
在该实施例中，密封结构的硬度和防形变层的硬度之间的比例为1:3。
硬度的大小与挤压强度的变化有关，低硬度的硅凝胶14在受力度上稍差，高硬度的硅橡胶15具有高挤压强度。具体地，防形变层的硅橡胶15硬度大于硅凝胶14的硬度。较软的硅凝胶14对金属键合丝不会产生压应力且能够保护键合金属丝。
在该实施例中，外壳11由环氧树脂制成；
优选地，与环氧胶13具有相同热膨胀系数的环氧树脂制成的外壳11，在受热时会与固化的环氧胶13体积一同膨胀，能够避免在较高工作温度下环氧胶13与外壳11之间产生间隙。
在该实施例中，密封结构是在散热底板1和外壳11形成的容置腔体的下部设置的8mm-12mm的硅凝胶14，防形变层是在硅凝胶14上设置的1mm-2mm的硅橡胶15，其中，硅凝胶14和硅橡胶15经过真空脱泡处理。
硅橡胶15、硅凝胶14经过真空脱泡处理，消除了微气泡，在低压环境应用IGBT电气单元时，虽然IGBT电气单元内外存在气压差，也不会出现微气泡在高压电场作用下的局部放电现象，不会造成有机绝缘的灌封体的老化分解，提高了IGBT电气单元封装件的可靠性。
硅凝胶14厚度范围在8mm-12mm，能有效的将陶瓷覆铜基板的功率基板2、信号基板3、绝缘栅双极型晶体管芯片4、二极管芯片5和全部的金属键合丝8保护在内，避免引线漏出造成耐压不足等问题；防形变层的硅橡胶15设置在硅凝胶14上。硅橡胶15厚度1mm-2mm，适宜的厚度具有较高的硬度，能有效防止硅凝胶14在低气压环境下发生气泡析出的问题，同时也在防形变层与盖板12之间留出一定空间，防止硅橡胶15和硅凝胶14发生的热膨胀挤压盖板12和外壳11。
如图1、图2、图3所示，在该实施例中，IGBT电气单元包括：
陶瓷覆铜基板，焊接在散热底板1上,其中，陶瓷覆铜基板包括相互分离的功率基板2和信号基板3，功率基板2和信号基板3之间通过铝键合线8键合连接；
绝缘栅双极型晶体管芯片4、二极管芯片5，绝缘栅双极型晶体管芯片4和二极管芯片5焊接在功率基板2上，通过铝键合线8键合连接；和
信号端子7、功率端子6，分别使用钎焊工艺焊接在陶瓷覆铜基板上，其中，信号端子7的固定端钎焊连接到信号基板3上，功率端子6的固定端钎焊连接到功率基板2上，信号端子7的自由端、功率端子6的自由端由外壳11或盖板12的开口处伸出；
功率端子6的固定端在功率基板2上的焊接位置、绝缘栅双极型晶体管芯片4在功率基板2上的焊接位置和二极管芯片5焊接在功率基板2上的焊接位置相互分离；
IGBT电气单元的功率基板2、信号基板3、绝缘栅双极型晶体管芯片4、二极管芯片5、铝键合线8、信号端子7的下部和功率端子6的下部包含在硅凝胶14内；
散热底板1由含有55%体积分数的AlSiC的复合材料制成；
陶瓷覆铜基板为AlN陶瓷覆铜基板；
绝缘栅双极型晶体管芯片4和二极管芯片5与AlN陶瓷覆铜基板的功率基板2之间使用纳米Ag焊膏、使用低温低压焊接工艺焊接连接。
在该实施例中的IGBT电气单元为半桥式IGBT电气单元。
本实施例中散热底板1采用55%体积分数的AlSiC复合材料，相比于传统底板，密度由7.8g/cm3下降到2.99 g/cm3，相同体积下模块重量大幅度下降。
在该实施例中，绝缘栅双极型晶体管芯片4的背面电极和二极管芯片5的背面电极与AlN陶瓷覆铜基板的功率基板2的表面之间焊接连接，绝缘栅双极型晶体管芯片4和二极管芯片5在焊接过程中受到8MPa压力，烧结温度250℃，保温时间50s。
采用AlN陶瓷直接覆铜基板，相比于传统的氧化铝陶瓷覆铜基板，AlN陶瓷热导率提升了近10倍，绝缘栅双极型晶体管芯片4、二极管芯片5与陶瓷直接覆铜基板之间连接采用纳米Ag焊膏低压烧结工艺，相比于传统高铅钎料，互连接头热导率提升了3倍多，耐温度能力不低于200℃，使IGBT电气单元的可靠性进一步提升。
在该实施例中，由超声键合工艺和铝键合线8形成绝缘栅双极型晶体管芯片4的正面电极和二极管芯片5的正面电极与AlN陶瓷覆铜基板的功率基板2的表面覆铜层之间的电连接；
功率基板2和信号基板3之间通过铝键合线8键合连接。
由真空钎焊工艺和锡铅共晶焊料，形成功率基板2和信号基板3与散热底板1的电连接。
由热风回流焊工艺和锡铅共晶焊料，形成信号端子7的固定端与信号基板3的电连接，及功率端子6的固定端与功率基板2的电连接。
使用超声键合工艺对铝键合线8施加超声波，对材料的塑性变形产生的影响，类似于加热。超声波能量被铝键合线8中的位错选择性吸收，从而位错在束缚位置解脱出来，致使铝键合线8在很低的外力下即可处于塑性变形状态。在这种状态下变形的铝键合线8，可以使处在蒸镀状态下的铝膜表面形成的氧化膜破坏，露出清洁的金属表面，利于键合操作。
根据本发明的另一个实施例的IGBT电气单元封装件还包括栅极电阻和稳压二极管，由钎焊工艺形成栅极电阻、稳压二极管与信号基板3的表面的电连接。
绝缘栅双极型晶体管芯片4、二极管芯片5的栅射或栅源极之间是容性结构，栅极回路的寄生电感又是不可避免的。优选地，串联一个栅极电阻消除栅极回路在驱动器驱动脉冲的激励下要产生很强的栅极振荡。 同时栅极电阻可以起到转移驱动器的功率损耗，降低温升的作用。表面栅极击穿造成IGBT电气单元封装件失效。
在该实施例中，功率端子6伸出盖板12或外壳11的自由端设置折弯部，在功率端子6的折弯部设置通孔10，盖板12上设置带有螺纹孔的安装基座9，安装基座9的位置与通孔10相匹配。
本发明的另一个实施例中其余部分均与一个实施例中的相同。
上述内容仅为本发明的具体实施方式的例子，对于其中未详尽描述的设备和结构，应当理解为采取本领域已有的通用设备及通用方法来予以实施。
以上仅为本发明的实施方式而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种IGBT电气单元封装件，包括：散热底板（1）、外壳（11）、盖板（12）和IGBT电气单元，所述IGBT电气单元焊接于所述散热底板（1）的上表面，其特征在于，所述外壳（11）的下部和所述散热底板（1）之间使用密封胶气体密封地固定粘接，所述外壳（11）的上部与所述盖板（12）之间使用密封胶气体密封地固定粘接；
    在所述散热底板（1）和所述外壳（11）形成的容置腔体的下部灌封硅凝胶（14），以形成密封结构，所述IGBT电气单元基本包含在所述硅凝胶（14）内；
    在所述硅凝胶（14）上设置防形变层，所述防形变层位于所述盖板（12）的下方。
  2. 根据权利要求1所述的IGBT电气单元封装件，其特征在于，所述外壳（11）的下部和所述散热底板（1）之间使用环氧胶固定粘接，所述外壳（11）的上部与所述盖板（12）之间使用环氧胶固定粘接；
    所述防形变层是硅橡胶层。
  3. 根据权利要求2所述的IGBT电气单元封装件，其特征在于，所述密封结构的硬度和所述防形变层的硬度之间的比例为1:（3-4）。
  4. 根据权利要求3所述的IGBT电气单元封装件，其特征在于，所述外壳（11）由热膨胀系数与环氧胶（13）的热膨胀系数之比为（0.8-1.2）：1的材料制成。
  5. 根据权利要求4所述的IGBT电气单元封装件，其特征在于，所述密封结构是在所述散热底板（1）和所述外壳（11）形成的容置腔体的下部设置的8mm-12mm的硅凝胶（14），所述防形变层是在所述硅凝胶（14）上设置的1mm-2mm的硅橡胶（15），其中，所述硅凝胶（14）和所述硅橡胶（15）经过真空脱泡处理。
  6. 根据权利要求5所述的IGBT电气单元封装件，其特征在于，所述IGBT电气单元包括：
    陶瓷覆铜基板，焊接在所述散热底板（1）上,其中，所述陶瓷覆铜基板包括相互分离的功率基板（2）和信号基板（3），所述功率基板（2）和所述信号基板（3）之间通过金属键合线键合连接；
    绝缘栅双极型晶体管芯片（4）、二极管芯片（5），所述绝缘栅双极型晶体管芯片（4）和所述二极管芯片（5）焊接在所述功率基板（2）上，通过金属键合线键合连接；和信号端子（7）、功率端子（6），分别使用钎焊工艺焊接在所述陶瓷覆铜基板上，其中，所述信号端子（7）的固定端钎焊连接到所述信号基板（3）上，所述功率端子（6）的固定端钎焊连接到所述功率基板（2）上，所述信号端子（7）的自由端、所述功率端子（6）的自由端由所述外壳（11）或所述盖板（12）的开口处伸出；
    所述功率端子（6）的固定端在所述功率基板（2）上的焊接位置、所述绝缘栅双极型晶体管芯片（4）在所述功率基板（2）上的焊接位置和所述二极管芯片（5）焊接在所述功率基板（2）上的焊接位置相互分离；
    所述IGBT电气单元的所述功率基板（2）、所述信号基板（3）、绝缘栅双极型晶体管芯片（4）、二极管芯片（5）、金属键合线、所述信号端子（7）的下部和所述功率端子（6）的下部包含在所述硅凝胶（14）内；
    所述散热底板（1）由含有52%-58%体积分数的AlSiC的复合材料制成；
    所述陶瓷覆铜基板为AlN陶瓷覆铜基板；
    所述绝缘栅双极型晶体管芯片（4）和所述二极管芯片（5）与所述AlN陶瓷覆铜基板的所述功率基板（2）之间使用纳米Ag焊膏、使用低温低压焊接工艺焊接连接。
  7. 根据权利要求6所述的IGBT电气单元封装件，其特征在于，所述绝缘栅双极型晶体管芯片（4）的背面电极和所述二极管芯片（5）的背面电极与所述AlN陶瓷覆铜基板的所述功率基板（2）的表面之间焊接连接，所述绝缘栅双极型晶体管芯片（4）和所述二极管芯片（5）在焊接过程中受到5MPa-11MPa压力，烧结温度200℃-300℃，保温时间40s-60s。
  8. 根据权利要求7所述的IGBT电气单元封装件，其特征在于，由超声键合工艺和铝键合线（8）形成所述绝缘栅双极型晶体管芯片（4）的正面电极和所述二极管芯片（5）的正面电极与所述AlN陶瓷覆铜基板的所述功率基板（2）的表面覆铜层之间的电连接；
    所述功率基板（2）和所述信号基板（3）之间通过铝键合线（8）键合连接；
    由真空钎焊工艺和锡铅共晶焊料，形成所述功率基板（2）和所述信号基板（3）与所述散热底板（1）的电连接；
    由热风回流焊工艺和锡铅共晶焊料，形成所述信号端子（7）的固定端与所述信号基板（3）的电连接，及所述功率端子（6）的固定端与所述功率基板（2）的电连接。
  9. 根据权利要求8所述的IGBT电气单元封装件，其特征在于，还包括栅极电阻和稳压二极管，由钎焊工艺形成所述栅极电阻、所述稳压二极管与所述信号基板（3）的表面的电连接。
  10. 根据权利要求9所述的IGBT电气单元封装件，其特征在于，所述功率端子（6）伸出盖板（12）或外壳（11）的自由端设置折弯部，在所述功率端子（6）的折弯部设置通孔（10），所述盖板（12）上设置带有螺纹孔的安装基座（9），所述安装基座（9）的位置与所述通孔（10）相匹配。
PCT/CN2022/115614 2021-11-30 2022-08-29 一种igbt电气单元封装件 WO2023098184A1 (zh)

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