CN-122028737-A - Packaging structure for improving overcurrent capacity of power device

Abstract

The invention belongs to the technical field of device packaging, and discloses a packaging structure for improving the overcurrent capacity of a power device, which comprises a metal substrate, a ceramic copper-clad plate, an IGBT chip, an FRD chip, a phase change material thermal buffer module and a power terminal, wherein the metal substrate is arranged on the ceramic copper-clad plate; the thermal resistance-heat capacity collaborative optimization module disclosed by the invention simultaneously utilizes the upper surface and the lower surface of the chip to carry out heat management, and can realize a double-sided heat dissipation structure with ultralow thermal resistance at the bottom and high equivalent heat capacity at the top in transient state, so that heat flow generated in overload can be rapidly dispersed. The source electrode of the IGBT chip is connected with a metal frame filled with PCM through a 1mm molybdenum block, and is connected with copper on the upper layer of DBC through copper foil, and the leadless structure shows higher reliability under the conditions of frequent overload and current impact.

Inventors

• WANG ZHIQIANG
• Tang Lewen
• HU JIABING

Assignees

• 华中科技大学

Dates

Publication Date

20260512

Application Date

20251224

Claims (10)

1. 1. The packaging structure for improving the overcurrent capacity of the power device is characterized by comprising a metal substrate, a ceramic copper-clad plate, a power chip layer, a phase change material thermal buffer module and a power terminal; the metal substrate is a planar aluminum plate and is used for bearing the ceramic copper-clad plate and forming a mechanical support; the upper surface of the ceramic copper-clad plate is provided with a power chip layer, and the power chip layer comprises an insulated gate bipolar transistor chip and a fast recovery diode chip; The phase change material thermal buffer module is arranged above the power chip layer and is used for absorbing phase change latent heat during overcurrent operation so as to inhibit the rise of the junction temperature of the chip; The power terminal is used for connecting the input side, the output side and the decoupling capacitor to form a minimum commutation loop.
2. 2. The package structure of claim 1, wherein the ceramic copper-clad plate comprises two types of aluminum nitride copper-clad plate and diamond copper-clad plate, the aluminum nitride copper-clad plate provides electrical insulation property, the diamond copper-clad plate provides high heat conduction channels, and the two are arranged on the metal substrate in a staggered manner and are electrically connected through copper foil to form a complete current path.
3. 3. The package structure of claim 1, wherein in the power chip layer, the drain electrode of the insulated gate bipolar transistor chip is fixedly connected with the diamond copper-plated plate through nano silver sintering material, the source electrode of the chip is thermally coupled with the phase-change module through a molybdenum block with the thickness of 1mm, and the gate electrode is connected with the corresponding control end platform through a bonding wire.
4. 4. The package structure of claim 1, wherein the fast recovery diode chip is arranged in anti-parallel with the insulated gate bipolar transistor chip, the diode anode is welded to the lower surface of the phase change module through a molybdenum block, and the cathode is in heat conduction connection with the diamond copper plating plate through a nano silver sintered layer.
5. 5. The package structure of claim 1, wherein the phase change material thermal buffering module comprises a high heat conduction metal frame and a metal phase change material, the metal frame is a hollow copper body, the bottom is sealed by a copper sheet, the top is 0.2 mm thick, the solid phase change metal is filled in the metal frame, and when the working temperature reaches a set phase change point, the solid phase change metal absorbs latent heat to realize thermal buffering.
6. 6. The package structure of claim 5, wherein the phase change temperature is controlled by material alloy ratio to make the difference between the phase change point and the steady-state junction temperature of the chip not greater than 10 ℃ so as to ensure the rapidity of thermal response in the case of overcurrent transient.
7. 7. The package structure of claim 1, wherein the metal substrate is uniformly coated with a thermally conductive silicone grease layer having a thickness of 0.1 mm, for reducing interface thermal resistance between the substrate and the ceramic copper-clad plate and improving overall heat flux density uniformity.
8. 8. The package structure of claim 1, wherein the diamond-coated copper plate is arranged only on the lower surface of the chip, and the driving circuit is provided by the adjacent ceramic plate, so that the design of electric-thermal separation is realized, and the manufacturing cost of the diamond-coated copper plate is greatly reduced.
9. 9. The package structure of claim 1, wherein the nano-silver sintered layer has a thickness of 20 microns to 30 microns, and a continuous network of silver crystals is formed within the sintered layer such that the interfacial thermal conductivity is not less than 200 watts per meter per kelvin.
10. 10. The package structure of claim 1, wherein the package structure achieves synergistic optimization of near junction high heat capacity on the upper surface and low thermal resistance on the lower surface by forming parallel heat conduction paths in the vertical direction from the chip to the phase change module and the chip to the diamond copper plate.

Description

Packaging structure for improving overcurrent capacity of power device Technical Field The invention belongs to the technical field of device packaging, and particularly relates to a packaging structure for improving overcurrent capacity of a power device. Background With the continuous development of new energy technology, a large number of power electronic devices are widely applied to links such as power generation, power transmission, power distribution and the like of a power system by virtue of the flexibility of the power electronic devices in terms of electric energy conversion, parameter configuration and the like, the traditional electromagnetic conversion equipment mainly comprising synchronous generators is gradually replaced, and the novel power system presents the characteristics of 'double heights' of 'high-proportion new energy' and 'high-proportion power electronic equipment'. However, the existing power converter lacks of stable operation capability under the condition of grid faults, so that transient accidents frequently occur, and the power supply reliability of a power system is seriously reduced. In recent years, network converters have gained increasing attention. By simulating the characteristics of the synchronous generator, the grid-constructed converter can provide voltage and frequency support when the power grid fails, and good stability is maintained under a weak power grid. However, unlike synchronous generators, the power electronics in the current transformer have limited overcurrent and overheat tolerance, and the supporting capability of the grid-constructed current transformer is severely insufficient in the event of grid faults. In particular, grid converters need to provide transient currents well above nominal to support grid voltage and frequency when a short circuit or large disturbance occurs in the grid. However, the overcurrent capability of the power semiconductor switch such as the IGBT can only reach 1.2 to 1.5 times of rated current generally, the duration is extremely short (hundreds of milliseconds), and if overload is carried out for a long time, junction temperature can rise sharply, and thermal breakdown and even permanent damage of the device are caused. Therefore, the research on the packaging structure capable of reliably operating under short-time high current has extremely important significance for the stable operation of the novel power system under the power grid fault condition. According to the Cauer thermal network model, reducing thermal resistance and improving heat capacity are two key physical ways of enhancing the overcurrent capacity of the power module. The lower thermal resistance is beneficial to improving the heat dissipation efficiency and slowing down the accumulation rate of the heat in the heat source area of the chip, thereby effectively inhibiting the rise of junction temperature. However, current thermal resistance optimization strategies focus primarily on thermal interface materials and heat sinks behind the substrate. The inherent large thermal inertia and slow thermal response speed of these structures makes it difficult to efficiently respond to transient over-current impacts on the order of hundred milliseconds-the heat has formed localized hot spots inside the chip before it is transferred to the level. Thus, such schemes are typically used to reduce steady state junction temperature, increase system capacity, and only as an adjunct to transient thermal management. On the other hand, the high heat capacity material is integrated into the power module, so that the carrying capacity of the module to transient overcurrent can be remarkably improved. The phase change material (PHASE CHANGE MATERIAL, PCM) is an effective means for improving the transient heat management performance by virtue of the characteristic that the phase change material absorbs a large amount of latent heat at a specific phase change temperature point and keeps the temperature basically unchanged. A common way is to encapsulate the solid PCM in a metal shell and attach the composite structure to the bottom of the chip to clamp the rapid rise in junction temperature. The heat conduction coefficient of the PCM is limited by lower heat conduction coefficient, if the PCM is directly placed in a main heat transfer path, the junction flow heat resistance is obviously increased, and the steady-state heat dissipation performance is further weakened. In addition, in the phase change process, the melted PCM can form a liquid film between the heat source and the solid phase PCM, the liquid film further increases the interface thermal resistance, reduces the heat flow density, and leads to the difficulty in effectively controlling the junction temperature of the chip under the action of continuous power. Related patent US10123456B2 discloses a method of enclosing a Phase Change Material (PCM) within a metal housing to form a heat sink structure. The structure com