EP-4736226-A1 - POWER MODULE AND METHOD FOR PRODUCING A POWER MODULE

EP4736226A1EP 4736226 A1EP4736226 A1EP 4736226A1EP-4736226-A1

Abstract

A power module (1) is provided comprising - at least one power semiconductor chip (2), and - a heat buffer (4) thermally conductively connected to the at least one power semiconductor chip (2), wherein - the heat buffer (4) comprises a container (5) of a first material with a cavity, and - the heat buffer (4) comprises a filler (6) of a second material different from the first material arranged within the cavity, and - the second material is a phase change material. Additionally, a method for producing a power module (1) is provided.

Inventors

SOLEIMAN ZADEH ARDEBILI, Reza
PAVLICEK, Niko
NAWAZ, MUHAMMAD
LIU, CHUNLEI
BEYER, HARALD

Assignees

Hitachi Energy Ltd

Dates

Publication Date: 20260506
Application Date: 20230630

Claims (1)

P2023,0640 WO E / P220308WO01 June 30, 2023 - 24 - Claims 1. Power module (1) comprising - at least one power semiconductor chip (2), and - a heat buffer (4) thermally conductively connected to the at least one power semiconductor chip (2), wherein - the heat buffer (4) comprises a container (5) of a first material with a cavity, and - the heat buffer (4) comprises a filler (6) of a second material different from the first material arranged within the cavity, and - the second material is a phase change material. 2. Power module (1) according to claim 1, wherein - the container (5) completely encapsulates the filler (6) three dimensionally. 3. Power module (1) according to one of the claims 1 or 2, wherein - the heat buffer (4) further comprises a heat spreading structure (14) of a third material, and - the heat spreading structure (14) is arranged within the cavity. 4. Power module (1) according to claim 3, wherein - the heat spreading structure (14) connects a bottom surface of the container (5) and a top surface of the container (5). 5. Power module (1) according to one of the claims 3 or 4, wherein - the heat spreading structure (14) is formed of at least one of a pillar, a rib, a porous structure. P2023,0640 WO E / P220308WO01 June 30, 2023 - 25 - 6. Power module (1) according to one of the claims 1 to 5, wherein - the first material is formed electrically conductive, and - the first material comprises at least one of copper, aluminum or a corresponding alloy, boron doped diamond, copper diamond composites, graphene, carbon nano tubes, graphite, hexagonal boron nitride, silicon carbide, ceramics, composite or a combination thereof. 7. Power module (1) according to one of the claims 1 to 6, wherein - the second material has a thermal conductivity of at least 0.1 W/(m*K), a phase change enthalpy of at least 20 J/g, and/or a temperature of phase change of at least 80°C. 8. Power module (1) according to one of the claims 1 to 7, wherein - the second material comprises of at least one of indium, In, bismuth, Bi, selenium, Sn or a combination thereof. 9. Power module (1) according to one of the claims 3 to 8, wherein - the third material is formed thermally conductive, and - the third material comprises at least one of copper, aluminum or corresponding alloy, diamond, boron doped or undoped diamond, graphene, carbon nano tubes, graphite, hexagonal boron nitride, silicon carbide, ceramics or a combination thereof. 10. Power module (1) according to one of the claims 1 to 9, wherein P2023,0640 WO E / P220308WO01 June 30, 2023 - 26 - - a heat spreading layer (7) is arranged between the at least one power semiconductor chip (2) and the heat buffer (4), and - the heat spreading layer (7) is formed of a fourth material being formed thermally conductive. 11. Power module (1) according to one of the claims 1 to 10, wherein - an additional heat spreading layer (8) is arranged on a main surface of the power semiconductor chip (2) facing away from the heat buffer (4), and - the additional heat spreading layer (8) is formed of a fifth material being formed thermally conductive. 12. Power module (1) according to one of the claims 10 or 11, wherein - the fourth material and/or the fifth material is comprises at least one of boron-doped or undoped diamond, hexagonal boron nitride, Cu-diamond, Ag-diamond, chemical vapor deposition grown diamond, single-crystal diamond, and graphene. 13. Power module (1) according to one of the claims 1 to 12, wherein - the at least one power semiconductor chip (2) comprises at least two power contacts, and - the heat buffer (4) is electrically conductively connected to one of the at least two power contacts. 14. Power module (1) according to one of the claims 1 to 13, wherein - the power module (1) further comprises a baseplate (3) on which the at least one power semiconductor chip (2) is arranged. P2023,0640 WO E / P220308WO01 June 30, 2023 - 27 - 15. Power module (1) according to one of the claims 1 to 14, wherein - the power module (1) further comprises a substrate (9) on which the power semiconductor chip (2) is arranged, - the substrate (9) comprises an electrically insulating layer (10), and - the substrate (9) comprises a first metallization (11) and a second metallization (12) between which the electrically insulating layer (10) is arranged. 16. Power module (1) according to claim 15, wherein - the substrate (9) is arranged between the baseplate (3) and the at least one power semiconductor chip (2). 17. Power module (1) according to one of the claims 15 or 16, wherein at least one of - the heat buffer (4) is arranged on a main surface of the power semiconductor chip (2) facing away from the substrate (9), - the heat buffer (4) is arranged between the power semiconductor chip (2) and the substrate (9), and - the heat buffer (4) is arranged between the substrate (9) and the baseplate (3). 18. Power module (1) according to one of the claims 1 to 17, wherein - the power module (1) further comprises a cooler (13) on which the baseplate (3) is arranged. 19. Method for producing a power module (1), with - providing at least one power semiconductor chip (2), - providing a heat buffer (4), P2023,0640 WO E / P220308WO01 June 30, 2023 - 28 - - arranging the heat buffer (4) on the at least one power semiconductor chip (2) such that the heat buffer (4) is thermally conductively connected to the at least one power semiconductor chip (2), wherein - the heat buffer (4) comprises a container (5) of a first material with a cavity, - the heat buffer (4) comprises a filler (6) of a second material different from the first material arranged within the cavity, and - the second material is a phase change material.

Description

P2023,0640 WO E / P220308WO01 June 30, 2023 - 1 - Description POWER MODULE AND METHOD FOR PRODUCING A POWER MODULE The present disclosure relates to a power module and a method for producing a power module. Power semiconductor modules comprising power semiconductor chips are essential integrated parts of power converters, providing basic building blocks in a diverse range of power electronic systems. Heat generated by the power semiconductor chips, e.g. during a converter operation, is typically dissipated by a heat sink. Typically, a thermal design of the power module with heat sink is according to nominal operations in a steady state, while including a small margin to accommodate for variations around a nominal operating point. However, in many applications, e.g. including high voltage direct current, HVDC, applications it is important and beneficial that power or current can be increased significantly for a certain amount of time, i.e., to be overloaded, resulting in higher losses during the overload. Depending on how demanding an overload profile is, increased heat fluxes can result in temporary high junction temperatures that can damage the semiconductor chip and compromise the operation. A transient thermal response of the power module to heat, i.e., a thermal impedance, Zth,, mainly depends on a thermal conductivity and a heat capacity and a density or specific gravity of the materials surrounding the power semiconductor device, while a steady state thermal resistance, Rth, mainly depends on a thermal conductivity of the materials P2023,0640 WO E / P220308WO01 June 30, 2023 - 2 - surrounding the power semiconductor device and a heat extraction coefficient of a cooler connected to the heat sink. While better cooling or materials with a higher thermal conductivity can lead to reduced Rth and junction temperatures in steady state, it is important to reduce Zth during the overload and hence to lower the transient junction temperatures for stable converter operation. Embodiments of the disclosure relate to a power module, with an improved thermal performance, especially an improved transient thermal behaviour. A further embodiment relates to a method for producing such a power module. This is achieved by the subject-matter of the independent claims. Further embodiments are evident from the dependent claims and the following description. A power module is described. The term “power” here and in the following, for example, refers to power modules, power semiconductor devices and/or power semiconductor chips adapted for processing voltages and currents of more than 100 V and/or more than 10 A, exemplary voltages up to 10 kV and electrical currents up to 10 kA. According to an embodiment, the power module comprises at least one power semiconductor chip. The power semiconductor chip comprises, for example, a semiconductor material such as at least one of silicon (Si), silicon carbide (SiC), and gallium nitride (GaN). The power semiconductor chip is, for example, a power diode and/or a power metal insulating semiconductor field-effect transistor, power MISFET for short. The term MISFET shall P2023,0640 WO E / P220308WO01 June 30, 2023 - 3 - also comprise MOSFETs, which have an oxide as insulating material at a gate. The power semiconductor chip may also be an insulated-gate bipolar transistor, IGBT. According to the embodiment, the power module comprises a heat buffer thermally conductively connected to the at least one power semiconductor chip. The heat buffer is, for example, directly arranged on the power semiconductor chip or at least one element is arranged between the heat buffer and the power semiconductor chip. According to the embodiment of the power module, the heat buffer comprises a container of a first material with a cavity. Exemplarily, the container has a top wall opposite a bottom wall, wherein the top wall and the bottom wall are connected by at least one side wall. The top wall, the bottom wall and the side wall are in particular formed of the first material forming, e.g. an integral structure. Inner surfaces of the top wall, the bottom wall and the side wall facing one another delimit and/or define the cavity. In particular, the cavity is completely enclosed three dimensionally from the container, i.e. the top wall, the bottom wall and the side wall. According to the embodiment of the power module, the heat buffer comprises a filler of a second material different from the first material arranged within the cavity. Exemplarily, the cavity is partially filled with the filler. This is that the cavity is filled with the filler to at most 95 %, at most 80 % or at most 50 %. A portion of the cavity being not filled with the filler comprises air, gases or vacuum. Alternatively, the filler fills the cavity completely. P2023,0640 WO E / P220308WO01 June 30, 2023 - 4 - According to the embodiment of the power module, the second material is a phase change material. A phase change material can und