Heat dissipating assembly with multi-layered thermal interface compound

Abstract

The disclosure relates to a heat dissipating assembly (100a) mountable between a circuit board (113) and a heat sink (115), the heat dissipating assembly (100a), comprising: a power package (110) mountable on the circuit board (113), the power package (110) comprising a heat dissipation interface (111) arranged at a main surface (117) of the power package (110), the main surface (117) opposite to the circuit board (113); and a multi-layered thermal interface compound (120) mounted onto the heat dissipation interface (111) of the power package (110); wherein the multi-layered thermal interface compound (120) comprises: a thermally conductive electrical isolation layer (122); and a thermally conductive elastic gap filling layer (121); wherein the electrical isolation layer (122) is electrically isolating, thereby enabling the elastic gap filling layer (121) to be electrically conductive or at least being composed of electrically conductive parts.

Description

[0001] HEAT DISSIPATING ASSEMBLY WITH MULTI-LAYERED THERMAL INTERFACE COMPOUND

[0002] TECHNICAL FIELD

[0003] The disclosure relates to the field of power converters and power packages with heat dissipation. In particular, the disclosure relates to a heat dissipation assembly with multi-layered thermal interface compound, specifically a package integrated isolating and shielding thermal interface material.

[0004] BACKGROUND

[0005] Power converters demanding a high efficiency and a high-power density are facing a multi-domain optimization dilemma with respect to the following parameters:

[0006] • Isolation - Dielectric stress endurance

[0007] • Power dissipation - Thermal management

[0008] • Manufacturing tolerances - Tolerance management

[0009] • Mechanical robustness - Mechanical strength, brittleness

[0010] • EMI shielding - Common mode conducted / radiated emissions

[0011] • Cost - Manufacturing complexity

[0012] Typically, optimization of one parameter results in poorer performance of the other parameters. The system is overdetermined and limited by material properties of single materials. As of today, a lot of products are not feasibly manufacturable because: High performance ceramic substrates are non-compliant, brittle, strain sensitive and expensive; Organic / polymeric isolation materials have inferior thermal and dielectric properties; Soft / compressive / compliant materials lack density, thermal conductivity, stability of isolation strength.

[0013] SUMMARY

[0014] This disclosure provides a solution for an isolation management within the thermal path of power converters. The solution is designed to achieve a high system level power density at high overall efficiency.

[0015] The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

[0016] Embodiments of the disclosure provide a board mountable power package with integrated isolated thermal interface that allows implementation of field grading and shielding. The structure and the method for manufacturing such structure is described hereinafter.

[0017] Embodiments of the disclosure provide an electrically isolated thermal interface available to board mounted power devices. The isolated thermal interface integrates gap filling capability without exposing scratch sensitive isolation layers. The isolated thermal interface is compatible with conventional SMA (surface mount assembly) or THT (through-hole technology). The isolated thermal interface provides isolation strength for power devices rated up to 1200V and above. The isolated thermal interface can have an Isolation layer that is thinner and mechanically more robust than ceramics (ceramics becomes to brittle for robust production when made thinner than 200 pm). The isolated thermal interface can additionally implement shielding. Use of field grading is presented for ever-thinner isolation layers. A scalable mass production process flow is presented for cost effective package manufacturing.

[0018] In this disclosure, a novel structure and a novel manufacturing / application method of a multilayered thermal interface compound is introduced. Embodiments of the disclosure enhance a conventional board mounted package with an electrical isolated cooling interface by applying a multi-layered compound to the surface.

[0019] The package integrated thermal interface has the advantage of reducing manufacturing complexity during the assembly of populated PCBs (Printed Circuit Boards) onto heatsinks or into housings with heatsink function. It eliminates the use of additional TIM (Thermal Interface Material) pastes, pads, isolations sheets, glues, etc. and simplifies isolation coordination.

[0020] The basic structure of the multi-layered compound is a high thermally conductive organic isolation layer that is bonded (ideally by its own resin system) to the non-isolated (usually metallic) thermal pad of a packaged component - and an elastic high thermally conductive gap filling layer that is bonded to the isolation layer (ideally by the resin system of the latter). The basic principle of this multi-layered compound is shown in Figure 1 described below.

[0021] This structure has the advantage that the thermal conductivity can be optimized in each of these layers separately, and a better overall thermal conductivity at high electrical isolation capability can be achieved: The choice of elastic gap filling material (TIM) can now include compounds that are electrically conductive and thus have a higher thermal conductivity than isolating materials.

[0022] Another advantage is that the elastic gap filling layer is protecting the sensitive isolation layer from mechanical damage during device handling in a manufacturing environment. Scratches or small particles in the gap filling layer will be tolerable as they do not cause any damage to the isolation layer underneath.

[0023] The structure can have one or more metal layers embedded (sandwiched) between two or more isolation layers as shown in Figure 1 described below. This metal layer can be used for EMI (Electro Magnetic Interference) shielding in combination with a through-package contact to electrically connect the metal layer with the relevant electrical potential on the PCB board.

[0024] The metal layer can also be used to integrate field grading or field shaping functions to the package. This allows to increase the breakdown voltage without increasing the thickness of the isolation layers.

[0025] The structure can comprise layers with field grading material or isolation layers that contain field grading material as part of the filler system. The field grading materials provide means to increase the breakdown voltage.

[0026] The structure can consist of a gliding layer on top of the multi-layer stack. This can be used to make the board assembly and attached cooler system more tolerant against cyclic thermal expansion.

[0027] In order to describe the disclosure in detail, the following terms and notations will be used. Aluminum Oxide AIN Aluminum Nitride

[0028] BMP Board Mounted Power

[0029] BN Boron Nitride

[0030] CNT Carbon Nano Tubes

[0031] DFN, DFN8, DFN-8 Dual Flat No-lead package (with 8 pins)

[0032] DSC Dual side cooled, package with exposed top side pad

[0033] EMI Electro Magnetic Interference

[0034] Fe20s, Fe2O3 Iron Oxide

[0035] FGM Field Grading Material

[0036] GLD Gliding, Gliding Layer

[0037] HV High Voltage

[0038] ISO Isolating, Isolation Layer

[0039] ATn. R_TH Thermal Resistance

[0040] SiC Silicon Carbide

[0041] SMA Surface Mount Assembly

[0042] SrTiO;. BaTiO, Strontium Titanate, Barium Titanate

[0043] SSO, SSO8, SSO-8 Super Small Outline package (with 8 pins)

[0044] SON Small Outline No-lead

[0045] TIM Thermal Interface Material

[0046] TO, TO-220, Transistor Outline package

[0047] TO-247 package Transistor Outline package

[0048] TOLT Thin Outline Lead less Top side cooled package

[0049] FBD, V_BD Breakdown Voltage

[0050] ZnO Zinc Oxide

[0051] Az, Lamda_z Vertical Thermal Conductivity, through-plane

[0052] Board mounted power package in this disclosure refers to an electronic package which is meant to be assembled on the surface of a printed circuit board (SMT, surface mount technology) or whose leads are mounted through holes in the PCB (THT, through-hole technology), which use the board as a reference plane. This is in contrast to frame based power modules or molded power modules, which are typically mounted onto the surface of a heatsink.

[0053] Power density is a key figure to describe how much rated power can be handled by a given power conversion device. Most common is a volumetric rate in W (W atts) or kW (Kilowatts) per 1 (Liter). High values require a very effective heat management and isolation coordination. An increase in power density allows the manufacturer to reduce effort and cost for housing and connections. Although typically a volumetric figure, an increase in power density also reduces required real estate.

[0054] Basic isolation is the isolation required for a powered (live) conductor against earth / ground potential in order to provide safe protection of humans under normal operating conditions. For example, the isolation layer between a power semiconductor drain connection and the heatsink. The heatsink typically is an electrical conductor and has ground potential. In contrast, functional isolation is the isolation of a powered conductor against another functional conductive part within the system in order to prevent malfunction or damage to the equipment. Thermal resistance is a value that describes how much increase of temperature in Kelvin causes 1 Watt of power, dissipated by the power conversion system along the described thermal path. The thermal resistance is always system specific and only valid for the specified and characterized system. In contrast, thermal conductivity describes the ability of a material to conduct heat. The value of thermal conductivity is ideally independent of the material thickness or volume. In practice, bulk values and interfacial values for thermal conductivity need to be considered.

[0055] Thermal path describes the flow of heat from the heat source - the power generating device - to the heatsink. In power electronics packaging, the main heat source is typically the junction, and the heat sink is typically a mounted heat sink, attached to the package with TIM (thermal interface material), or a cooling channel with coolant inside (liquid).

[0056] Thermal interface in this disclosure shall relate to a package interface that can be directly attached to a heat sink without the need of further TIM. This means that this interface provides tolerance gap filling functionality.

[0057] Field Grading is a technique used in high voltage cable terminations to reduce the electric field strength in air close to where the isolation of the wire ends. It refers to the introduction of material with a dielectric constant between that of air (= 1) and that of the cable isolation. This has the effect of smoothing out dielectric steps and reducing the electric field near the end of the isolation, thus avoiding arcing or other unwanted discharge phenomena. The use of field grading may increase the overall thickness by adding additional layers, however, the added layers will have a higher thermal conductivity such that the resulting thermal resistance can be lowered.

[0058] According to a first aspect, the disclosure relates to a heat dissipating assembly mountable between a circuit board and a heat sink, the heat dissipating assembly, comprising: a power package mountable on the circuit board, the power package comprising a heat dissipation interface arranged at a main surface of the power package, the main surface opposite to the circuit board; and a multi-layered thermal interface compound mounted onto the heat dissipation interface of the power package; wherein the multi-layered thermal interface compound comprises: a thermally conductive electrical isolation layer; and a thermally conductive elastic gap filling layer; wherein the electrical isolation layer is electrically isolating, thereby enabling the elastic gap filling layer to be electrically conductive or at least being composed of electrically conductive parts.

[0059] Such a heat dissipating assembly provides a solution for an isolation management within the thermal path of power converters. The heat dissipating assembly can achieve a high system level power density at high overall efficiency.

[0060] According to the heat dissipation assembly, the elastic gap filling material does not have to be electrically isolating. This is done already in the isolation layer. Such arrangement allows the gap filling material to be electrically conductive which enables selecting materials with higher thermal conductivity than isolating materials. The elastic gap filling material can comprise metallic or semiconducting filler particles or compounds like e. g. graphite, graphene, that have much higher thermal conductivity than the isolation layer.

[0061] In an exemplary implementation of the heat dissipating assembly, the thermally conductive electrical isolation layer is configured to electrically isolate the heat sink against an electrical potential of the heat dissipation interface of the power package; and the elastic gap filling layer is configured to fill the gaps between the heat sink surface and the electrical isolation layer. The heat dissipating assembly provides a Package integrated isolation and thermal interface which results in easier product manufacturing, less manual handling of delicate parts, less additional materials during final assembly such as isolation sheets, pastes, glues, etc. and less risk of forgotten parts or residues.

[0062] In an exemplary implementation of the heat dissipating assembly, the multi-layered thermal interface compound is configured for the minimum functionalities: heat transfer, electrical isolation, gap filling, and in addition one or more, but not limited to following optional functionalities: electrical shielding, gliding and field grading.

[0063] In an exemplary implementation of the heat dissipating assembly, the electrically conductive parts of the elastic gap filling layer have a higher thermal conductivity than the electrical isolation layer.

[0064] The elastic gap filling material does not have to be electrically isolating since this is already done by the isolation layer. Using electrically conductive material for the gap filling material allows to choose materials with higher thermal conductivity than isolating materials. Such material may comprise metallic or semiconducting filler particles or compounds like e. g. graphite, graphene, that have much higher thermal conductivity than the isolation layer.

[0065] In an exemplary implementation of the heat dissipating assembly, the elastic gap filling layer is configured to protect the electrical isolation layer from mechanical damage.

[0066] Mechanical damages may occur for example during manufacturing processes of the heat dissipating assembly, e.g., when mounting the heatsink or during pick and placement of the heat dissipating assembly onto the PCB. The elastic gap filling layer makes the heat dissipating assembly more robust against mechanical influences during production.

[0067] The usually soft gap filling material does not need to contribute to the electrical isolation. Thus, the overall isolation of the multilayer compound is scratch tolerant.

[0068] In an exemplary implementation of the heat dissipating assembly, the electrical isolation layer comprises a curable organic or polymer compound with thermal conductivity enhancing, electrically non-conductive fillers comprising at least one of the following: boron nitride, aluminum nitride, aluminum oxide, silicon oxide, silicon nitride and silicon carbide.

[0069] Such curable organic or polymer compound provides improved thermal conductivity.

[0070] In an exemplary implementation of the heat dissipating assembly, the gap filling layer comprises polymer matrix composites with electrically conductive or electrically non-conductive thermal conductivity enhancing fillers.

[0071] This provides design flexibility for implementing the gap filling layer.

[0072] In an exemplary implementation of the heat dissipating assembly, the thermal conductivity enhancing fillers of the polymer matrix comprise at least one of the following: metals, graphite, graphene, CNTs, carbon fibers, functionalized forms of graphite, graphene, CNTs, or carbon fibers, aluminum oxide, Boron nitride, Aluminum nitride and Silicon carbide.

[0073] This allows to use a variety of different materials for the polymer matrix. In an exemplary implementation of the heat dissipating assembly, the power package comprises a package body made of a molding material; wherein the heat dissipation interface of the power package is exposed at the main surface from the molding material of the package body; and wherein the electrical isolation layer fully covers the exposed heat dissipation interface of the power package. The heat dissipation interface usually is metallic and can have an electrical potential which needs to be isolated against the heatsink.

[0074] This enables an efficient electrical isolation of the exposed heat dissipation interface of the power package.

[0075] In an exemplary implementation of the heat dissipating assembly, the multi-layered thermal interface compound comprises one or more electromagnetic interference, EMI, shielding layers and / or field grading material, FGM, layers embedded inside the electrical isolation layer; wherein the one or more EMI shielding layers are configured to shield the power package from electromagnetic emissions; and wherein the one or more FGM layers are configured to reduce an electric field strength near the electrical isolation layer.

[0076] The heat dissipating assembly provides integrated shielding and field grading. By that, a lower RTH than in conventional packages can be achieved. Besides, the heat dissipation assembly allows high power density since the shielding is directly at the device, no additional voluminous screens etc. are needed.

[0077] As described above, field grading is a technique used in high voltage cable terminations to reduce the electric field strength in air close to where the isolation of the wire ends. It refers to the introduction of material with a dielectric constant between that of air (=1) and that of the cable isolation. The use of FGM layers has the effect of smoothing out dielectric steps and reducing the electric field near the end of the isolation, thus avoiding arcing or other unwanted discharge phenomena.

[0078] In an exemplary implementation of the heat dissipating assembly, the one or more EMI shielding layers comprise of one or more of the following: structured metal sheets or foils of Cu, Ni, Al, Au, Ag, Fe; structured sheets or foils of carbon-based materials, carbon fibers, carbon nanotubes, nanographene, graphite and / or graphene; composite polymeric materials with metal and / or carbon fillers including nano or microparticles, sheets, wires and nets.

[0079] This allows to produce the EMI shielding layers from a variety of different materials.

[0080] In an exemplary implementation of the heat dissipating assembly, the one or more FGM layers comprise of polymer-based isotropic or non-isotropic or layered composites with one or more fillers; wherein the fillers comprise at least one of the following: Strontium Titanate (SrTiOs), graphite, Barium Titanate (BaTiOs), Zinc Oxide (ZnO), Aluminum Oxide (AI2O3), Iron Oxide (FC2O ;). metal or carbon fillers as nano or microparticles, sheet or wires.

[0081] This allows to produce the FGM layers from a variety of different materials.

[0082] In an exemplary implementation of the heat dissipating assembly, the one or more EMI shielding layers and / or FGM layers are electrically connected to a through-package contact of the power package electrically connecting the EMI and / or FGM layers to a pre-defined electrical potential of a pad of the circuit board.

[0083] This allows to avoid floating electrical potentials within the heat dissipating assembly. In an exemplary implementation of the heat dissipating assembly, the multi-layered thermal interface compound comprises a gliding layer arranged between the gap filling layer and the heat sink; wherein the gliding layer is configured to provide an elastic, non-locking and / or friction-reducing interface between the gap filling layer and the heat sink.

[0084] By using such gliding layer, the heat sink can be elastically attached to the power package.

[0085] In configurations with large thermal interface areas, or large PCB boards with widely distributed heat dissipating components locking may lead to high shear forces that disrupt the thermal path. Accordingly, the gliding layer avoids shear forces and warpage in order to improve the robustness and integrity of the thermal path.

[0086] In an exemplary implementation of the heat dissipating assembly, the gliding layer comprises of one or more of the following: graphite, graphene, PTFE (polytetrafluoroethylene), Silicone, or other dry solid-state lubricants.

[0087] This allows to produce the gliding layer from a variety of different materials.

[0088] In an exemplary implementation of the heat dissipating assembly, the multi-layered thermal interface compound comprises a second elastic gap filling layer mounted between the isolation layer and the heat dissipation interface of the power package; wherein the second elastic gap filling layer is configured to fill the gaps between the heat dissipation interface of the power package and the electrical isolation layer.

[0089] Such second elastic gap filling layer allows the multi-layered thermal interface compound to be completely detachable from the heat dissipation interface of the power package and the heatsink.

[0090] In some assembly situations this can increase the flexibility of the production process and provide a simple option to enhance the TIM function in the assembly by one or more of the following additional functionalities: shielding, isolation, field grading, gliding.

[0091] In such an assembly situation, an existing pick & place action of a TIM layer or thermal pad is replaced by a pick & place action of the multi-layered thermal interface compound with a second elastic gap filling layer.

[0092] In an exemplary implementation of the heat dissipating assembly, the second elastic gap filling layer is configured to protect the electrical isolation layer and the power package from mechanical damage.

[0093] The second elastic gap filling layer together with the (first) elastic gap filling layer makes the heat dissipating assembly more robust against mechanical influences during production.

[0094] In an exemplary implementation of the heat dissipating assembly, an interface between the thermally conductive electrical isolation layer and the elastic gap filling layer forms a cured positive connection.

[0095] Such a cured positive connection provides a stable and robust mechanical connection of the power package to the heat sink. It provides a shortest thermal path with highest flexibility of assembly and lowest number of non-positive thermally lossy interfaces. The isolation layer may be bonded on the gap filling layer by means of a cured positive connection, for example, using a lamination process that may use the intrinsic resin system of the isolation layer.

[0096] In an exemplary implementation of the heat dissipating assembly, the elastic gap filling layer is electrically conductive.

[0097] This results in highest achievable thermal conductivity of a non-positive interface. The elastic gap filling layer provides protection against particles / scratches of isolation layer underneath, it enables a scratch-tolerant isolating TIM.

[0098] In the following, exemplary values for the different layers described above are given as examples without limiting the scope of these layer thicknesses.

[0099] The thermally conductive electrical isolation layer (ISO) may have an exemplary thickness of e.g., 20 .. 500 pm, typically 100 .. 150 pm.

[0100] The gap filling layer / elastic polymer layer (TIM) may have an exemplary thickness of e.g., 200 .. 2000 pm, typically 200 ... 400 pm.

[0101] The field grading material layer (FGM) conductive sheet / coating may have an exemplary thickness of e.g., 50 nm (e. g. sputtered Au) ... 70 pm (e. g. Cu foil).

[0102] The EMI shielding layer (EMI) may have an exemplary thickness of e.g., 50 nm (e. g. sputtered Au) ... 70 pm (e. g. Cu foil).

[0103] The gliding layer (GLD) may have an exemplary thickness of e.g., 10 nm .. 50 pm.

[0104] BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Further embodiments of the disclosure will be described with respect to the following figures, in which:

[0106] Figure 1 shows a cross section of heat dissipating assembly 100a according to the disclosure;

[0107] Figure 2 shows a cross section of heat dissipating device 200 according to a first embodiment;

[0108] Figure 3 shows a cross section of heat dissipating device 300 according to a second embodiment;

[0109] Figure 4 shows a cross section of heat dissipating device 400 according to a third embodiment;

[0110] Figure 5 shows a cross section of heat dissipating device 500 according to a fourth embodiment;

[0111] Figure 6 shows a schematic diagram illustrating a method for producing a heat dissipating device 600 according to a first embodiment; Figure 7 shows a schematic diagram illustrating a method for producing a heat dissipating device 700 according to a second embodiment; and

[0112] Figure 8 shows a schematic diagram illustrating a method for producing a heat dissipating device 800 according to a third embodiment.

[0113] DETAILED DESCRIPTION OF EMBODIMENTS

[0114] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the disclosure is defined by the appended claims.

[0115] It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

[0116] Figure 1 shows a cross section of heat dissipating assembly 100a according to the disclosure.

[0117] The heat dissipating assembly 100a (left side of Figure 1) can be mounted between a circuit board 113 and a heat sink 115 as shown on the right side of Figure 1 to form a heat dissipating device 100b.

[0118] The heat dissipating assembly 100a comprises a power package 110 mountable on the circuit board 113. The power package 110 comprises a heat dissipation interface 111 arranged at a main surface 117 of the power package 110. This main surface 117 is arranged opposite to the circuit board 113.

[0119] The heat dissipating assembly 100a comprises a multi-layered thermal interface compound 120 mounted onto the heat dissipation interface 111 of the power package 110.

[0120] The multi-layered thermal interface compound 120 comprises: a thermally conductive electrical isolation layer 122; and a thermally conductive elastic gap filling layer 121. As shown in Figure 1 , a laminated interface 123 may be formed between the two layers 122, 121.

[0121] The electrical isolation layer 122 is electrically isolating, thereby enabling the elastic gap filling layer 121 to be electrically conductive or at least being composed of electrically conductive parts.

[0122] According to the heat dissipation assembly, the elastic gap filling material of the gap filling layer 121 does not have to be electrically isolating. This is done already in the isolation layer 122. This allows the gap filling material to be electrically conductive - allows choice of materials with higher thermal conductivity than isolating materials. It can comprise metallic or semiconducting filler particles or compounds like e. g. graphite, graphene, that have much higher thermal conductivity than the isolation layer.

[0123] The thermally conductive electrical isolation layer 122 may be configured to electrically isolate the heat sink 115 against an electrical potential of the heat dissipation interface 111 of the power package 110.

[0124] The elastic gap filling layer 121 may be configured to fill the gaps between the heat sink 115 and the electrical isolation layer 122.

[0125] The multi-layered thermal interface compound 120 may be configured for the following functionalities: heat transfer, electrical isolation, gap filling, electrical shielding, gliding and field grading.

[0126] The electrically conductive parts of the elastic gap filling layer 121 can have a higher thermal conductivity than the electrical isolation layer 122.

[0127] The elastic gap filling material of the elastic gap filling layer 121 does not have to be electrically isolating since this is already done by the isolation layer 122. Using electrically conductive material for the gap filling material allows to choose materials with higher thermal conductivity than isolating materials. As described above, such material may comprise metallic or semiconducting filler particles or compounds like e. g. graphite, graphene, that have much higher thermal conductivity than the isolation layer.

[0128] The elastic gap filling layer 121 may be configured to protect the electrical isolation layer 122 from mechanical damage.

[0129] The usually soft gap filling material does not need to contribute to the electrical isolation. Thus, the overall isolation of the multilayer compound is scratch tolerant.

[0130] The electrical isolation layer 122 may comprise a curable organic or polymer compound with thermal conductivity enhancing, electrically non-conductive fillers comprising at least one of the following: boron nitride, aluminum nitride, aluminum oxide, silicon oxide, silicon nitride and silicon carbide, or others, for example.

[0131] The gap filling layer 121 may comprise polymer matrix composites with electrically conductive or electrically non-conductive thermal conductivity enhancing fillers, for example.

[0132] The thermal conductivity enhancing fillers of the polymer matrix may comprise at least one of the following: metals, graphite, graphene, CNTs, carbon fibers, functionalized forms of graphite, graphene, CNTs, or carbon fibers, aluminum oxide, boron nitride, aluminum nitride and silicon carbide, or others, for example.

[0133] The power package 110 may comprises a package body 114 that can be made of a molding material. The heat dissipation interface 111 of the power package HO canbe exposed at the main surface 117 from the molding material of the package body 114. The electrical isolation layer 122 may fully cover the exposed heat dissipation interface 111 of the power package 110. The heat dissipation interface 111 usually is metallic and can have an electrical potential which needs to be isolated against the heatsink 115. The multi-layered thermal interface compound 120 may comprise one or more electromagnetic interference (EMI) shielding layers 124 and / or field grading material (FGM) layers 124, for example, that may be embedded inside the electrical isolation layer 122. The one or more EMI shielding layers 124 may be configured to shield the power package 110 from electromagnetic interference. The one or more FGM layers 124 may be configured to reduce anelectric field strength near the electrical isolation layer 122.

[0134] The one or more EMI shielding layers 124 may comprise of one or more of the following: structured metal sheets or foils of Cu, Ni, Al, Au, Ag, Fe; structured sheets or foils of carbon-based materials, carbon fibers, carbon nanotubes, nanographene, graphite and / or graphene; composite polymeric materials with metal and / or carbon fillers including nano or microparticles, sheets, wires and nets, for example.

[0135] The one or more FGM layers 124 may comprise of polymer-based isotropic or non-isotropic or layered composites with one or more fillers, for example. The fillers may comprise at least one of the following: Strontium Titanate (SrTiOs), graphite, Barium Titanate (BaTiOs), Zinc Oxide (ZnO), Aluminum Oxide (AI2O3), Iron Oxide (FC2O ;). metal or carbon fillers as nano or microparticles, sheet or wires, for example.

[0136] The one or more EMI shielding layers and / or FGM layers can be electrically connected to a through-package contact 118 of the power package 110 electrically connecting the EMI and / or FGM layers to a pre-defined electrical potential of a pad 119 of the circuit board 113, for example.

[0137] The multi-layered thermal interface compound 120 may comprise a gliding layer 401 as shown in Figure 4, for example, arranged between the gap filling layer 121 and the heat sink 115, for example. The gliding layer 401 may be configured to provide an elastic, non-locking and / or friction-reducing interface between the gap filling layer 121 and the heat sink 115.

[0138] In configurations with large thermal interface areas, or large PCB boards with widely distributed heat dissipating components locking may lead to high shear forces that disrupt the thermal path. Accordingly, the gliding layer avoids shear forces and warpage in order to improve the robustness and integrity of the thermal path.

[0139] The gliding layer 401 may comprise of one or more of the following: graphite, graphene, PTFE, Silicone, or other dry solid- state lubricants, for example.

[0140] The multi-layered thermal interface compound 120 may comprise a second elastic gap filling layer 121b, as shown in Figure 5, for example, mounted between the isolation layer 122 and the heat dissipation interface 111 of the power package 110. The second elastic gap filling layer 121b may be configured to fill the gaps between the heat dissipation interface 111 of the power package 110 and the electrical isolation layer 122.

[0141] The second elastic gap filling layer 121b may be configured to protect the electrical isolation layer 122 and the power package 110 from mechanical damage.

[0142] An interface between the thermally conductive electrical isolation layer 122 and the elastic gap filling layer 121 may form a cured positive connection.

[0143] The elastic gap filling layer 121 can be electrically conductive. In the following, further embodiments of the heat dissipation assembly 110a and heat dissipation device 100b are described.

[0144] The left side of Figure 1 shows the heat dissipation assembly 100a, that represents a board mounted package 110 enhanced with a non-isolated cooling interface 117 by applying a multi-layered compound 120 to the surface 117.

[0145] This package integrated thermal interface 117 has the advantage of reducing manufacturing complexity during the assembly of PCB boards 113 onto heatsinks 115 or into housings with heatsink function. It eliminates the use of additional TIM pastes, pads, isolations sheets, glues, etc. and simplifies isolation coordination.

[0146] The basic structure of this multi-layered compound 120 is a high thermally conductive organic isolation layer 122 that is bonded (ideally by its own resin system) to the non-isolated (usually metallic) thermal pad 111 of a packaged component 112 - and an elastic high thermally conductive gap filling layer 121 that is bonded to the isolation layer 122 (ideally by the resin system of the latter).

[0147] This structure has the advantage that the thermal conductivity can be optimized in each of these layers separately, and a better overall thermal conductivity at high electrical isolation capability can be achieved: The choice of elastic gap filling material (TIM) can now include compounds that are electrically conductive and thus have a higher thermal conductivity than isolating materials.

[0148] Another advantage is that the elastic gap filling layer 121 is protecting the sensitive isolation layer 122 from mechanical damage during device handling in a manufacturing environment. Scratches or small particles in the gap filling layer 121 will be tolerable as they do not cause any damage to the isolation layer 122 underneath.

[0149] The structure can have one or more metal layers 124 embedded (sandwiched) between two or more isolation layers 122. This metal layer 124 can be used for EMI (Electro Magnetic Interference) shielding in combination with a through-package contact 118 to electrically connect the metal layer 124 with the relevant electrical potential on the PCB board 113.

[0150] The metal layer 124 can also be used to integrate field grading or field shaping functions to the package 110. This allows to increase the breakdown voltage without increasing the thickness of the isolation layers.

[0151] The structure can comprise layers with field grading material or isolation layers that contain field grading material as part of the filler system. The field grading materials provide means to increase the breakdown voltage.

[0152] The structure can consist of a gliding layer 401 as shown in Figure 4 on top of the multi-layer stack 120. This can be used to make the board assembly and attached cooler system more tolerant against cyclic thermal expansion.

[0153] In the following, exemplary values for the different layers described above are given as examples without limiting the scope of these layer thicknesses.

[0154] Thermally conductive electrical isolation layer (ISO) 122: 20 .. 500 pm, typically 100 .. 150 pm

[0155] Gap filling lay er / elastic polymer layer (TIM) 121: 200 .. 2000 pm, typically 200 ... 400 pm

[0156] Field grading material layer (FGM) conductive sheet / coating 124: 50 nm (e. g. sputtered Au) ... 70 pm (e. g. Cu foil) EMI shielding layer (EMI) 124: 50 nm (e. g. sputtered Au) ... 70 pm (e. g. Cu foil) Gliding layer (GLD) 401: 10 nm .. 50 pm. Figure 2 shows a cross section of heat dissipating device 200 according to a first embodiment.

[0157] The heat dissipating device 200 has the same structure as the heat dissipating device 100b shown in Figure 1 but is shown in the opposite direction, e.g., heat sink 115 at the bottom and PCB 113 at the top of Figure 2. A heat dissipating assembly 100a as shown in Figure 1 (left side of Figure 1) is mounted between the circuit board 113 and the heat sink 115 to form the heat dissipation device 200. The heat dissipating assembly 100a shown in Figure 2 is a heat dissipating assembly according to a first embodiment.

[0158] The heat dissipating device 200 comprises a circuit board 113, also referred to as PCB and a power package 110 mounted on the circuit board 113. The power package 110 comprises a heat dissipation interface arranged at a main surface of the power package 110 which is opposite to the circuit board 113.

[0159] The heat dissipating assembly 200 comprises a heat sink 115 for receiving heat from the heat dissipation interface of the power package 110; and a multi-layered thermal interface compound 120 mounted between the heat dissipation interface 111 of the power package 110 and the heat sink 115.

[0160] The through-board thermal path 210 and the thermal path 220 to heatsink are shown in Figure 2.

[0161] The multi-layered thermal interface compound 120 comprises: a thermally conductive electrical isolation layer 122 mounted onto the heat dissipation interface 111 of the power package 110; and a thermally conductive elastic gap filling layer 121 arranged between the isolation layer 122 and the heat sink 115.

[0162] The electrical isolation layer 122 is electrically isolating, thereby enabling the elastic gap filling layer 121 to be electrically conductive or at least being composed of electrically conductive parts.

[0163] The thermally conductive electrical isolation layer 122 is configured to electrically isolate the heat sink 115 against an electrical potential of the heat dissipation interface of the power package 110.

[0164] The elastic gap filling layer 121 is configured to fill the gaps between the heat sink 115 and the electrical isolation layer 122.

[0165] This first embodiment delineates a Package integrated 2-layer isolating thermal interface material with a force-fitted interface on an elastic thermal interface material (TIM) layer 121, bonded to an ISO (isolation) layer 122.

[0166] The ISO-layer 122 may comprise a curable organic / polymer compound with thermal conductivity enhancing, preferably electrically non-conductive fillers such as BN (boron nitride), AIN (aluminum nitride), SiC (Silicon carbide), etc. The ISO- layer may also include field-grading fillers or sublayers.

[0167] The TIM-layer 121 may comprise of polymer matrix composites with thermal conductivity enhancing fillers - one or more - that may be either electrically conducting or non-conducting such as metals, graphite, graphene, CNTs, carbon fibers, BN, AIN, SiC, etc. The bonding between the ISO 122 and TIM 121 layers can be enhanced by interlinking additives or processing methods that promotes adhesion. The layers may be applied to a package with exposed metallic non-isolated thermal pad, e. g. SSO8 DSC (super small outline 8-pin dual side cooled), TOLT (Thin outline lead less top side cooled), DFN8 dual cool (dual flat no-lead 8-pin dual cool); The ISO-layer 122 may fully cover the exposed metal of the package. Application can be done by a lamination method as described below.

[0168] Those packages can be manufactured using a map-molding technique, which means a matrix of several devices is molded into one thin block, which is then separated into individual packages by sawing.

[0169] The multi-layered thermal interface compound 120 can be applied to map-molded or panel-molded packages before separation.

[0170] Figure 3 shows a cross section of heat dissipating device 300 according to a second embodiment.

[0171] The heat dissipating device 300 has the same structure as the heat dissipating device 200 shown in Figure 2 but an additional metal layer 124 is embedded in the thermally conductive electrical isolation layer 122. A heat dissipating assembly 100a as shown in Figure 1 (left side of Figure 1) is mounted between the circuit board 113 and the heat sink 115 to form the heat dissipation device 300. The heat dissipating assembly 100a shown in Figure 3 is a heat dissipating assembly according to a second embodiment.

[0172] This second embodiment introduces a Package integrated isolating and shielding thermal interface multi-layer with one or more EMI shielding (EMI) layers 124, and / or field grading material (FGM) layers 124 between 2 or more curable ISO-layers 122, bonded to an elastic TIM layer 121. For simplicity, only a single metal layer 124 is shown in Figure 3. This metal layer 124 represents the EMI layers 124 and / or FGM layers 124 described in the following.

[0173] The EMI layers 124 can comprise of structured (etched, stamped, milled) metal sheets or foils of Cu, Ni, Al, etc., and / or that of carbon-based materials, such as carbon fibers, carbon nanotubes, nanographene, graphite, graphene, etc. The EMI layers 124 may also comprise of composite polymeric materials with metal and or carbon fillers - including nano / microparticles, sheets, wires, etc.

[0174] More than one EMI layers 124 can be used for field grading by assigning intermediate electrical potentials to each of the layers. Alternatively, or in combination - FGM layers 124 of polymer (silicone, epoxy)-based isotropic / non-isotropic or layered composites may be used with one or more fillers such as Strontium Titanate (SrTiOs, graphite (platelets / particles), Barium Titanate (BaTiOs), Zinc Oxide (ZnO), Aluminum Oxide (AI2O3), Iron Oxide (Fe2O3), metal / carbon fillers as nano / microparticles, sheets, wires, etc.

[0175] The EMI / FGM-layer(s) 124 may be fully embedded inside the ISO-layer 122 by means of a special processing method as described below.

[0176] The electrical potential of the EMIZFGM-layer(s) 124 may be defined by a through-package contact that connects to a via hole in the inner ISO-layer(s) 122, made by a special processing method as described below.

[0177] Figure 4 shows a cross section of heat dissipating device 400 according to a third embodiment. The heat dissipating device 400 has the same structure as the heat dissipating device 200 shown in Figure 2 but an additional gliding (GLD) layer 401 is attached to the elastic gap filling layer (TIM-layer) 121. A heat dissipating assembly 100a as shown in Figure 1 (left side of Figure 1) is mounted between the circuit board 113 and the heat sink 115 to form the heat dissipation device 400. The heat dissipating assembly 100a shown in Figure 4 is a heat dissipating assembly according to a third embodiment.

[0178] This third embodiment introduces a package integrated 2-layer isolating thermal interface material with one or more GLD (gliding) layers 401 bonded to the elastic TIM layer 121 or replacing the elastic TIM layer 121. For simplicity, only one GLD layer 401 is shown in Figure 4.

[0179] The GLD-layer 401 may be applied onto the outer face of the elastic layer 121 by means of lamination of a foil or deposition of a thin film.

[0180] The GLD-layer 401 may comprise graphite, graphene, PTFE, Silicone or other dry (solid state) lubricants.

[0181] Figure 5 shows a cross section of heat dissipating device 500 according to a fourth embodiment.

[0182] The heat dissipating device 500 has the same structure as the heat dissipating device 200 shown in Figure 2 but an additional elastic gap filling layer (TIM layer) 12 lb is attached to the isolation layer 122 such that the isolation layer 122 is sandwiched between two TIM layers 121, 121b. A heat dissipating assembly 100a as shown in Figure 1 (left side ofFigure 1) is mounted between the circuit board 113 and the heat sink 115 to form the heat dissipation device 500. The heat dissipating assembly 100a shown in Figure 5 is a heat dissipating assembly according to a fourth embodiment.

[0183] This fourth embodiment introduces a multilayer structure with two force-fitted TIM layers 121, 121b each on top and bottom of the ISO-layer stack 122. The ISO-layer stack 122 comprises of functional materials as described above with respect to Figures 2, 3 and 4, or a non-structured ceramic sheet or platelet sandwiched between the 2 TIM-layers 121, 121b.

[0184] This fourth embodiment allows for free cutting and applying the multi-layer structure as a sheet during final assembly. In some assembly situations this can increase the flexibility of the production process and provide a simple option to enhance the TIM function in the assembly by one or more of the following additional functionalities: shielding, isolation, field grading, gliding.

[0185] In the following Figures 6 to 8, two methods of applying the multilayer isolating TIM compound 120 for integration into a package are presented. Figures 6 and 7 illustrate an extension of a mold map based packaging process (mostly no-lead only, e. g. QFN, DFN, SON, SSO, etc. packages). Figure 8 illustrates a lamination onto existing singulated packages (mostly for leaded or no-lead board mounted packages).

[0186] Figure 6 shows a schematic diagram illustrating a method for producing a heat dissipating device 600 according to a first embodiment.

[0187] The method comprises Provision 601 of a map-molded leadframe 601 (option a) or a molded panel 601 (option b). The method comprises Lay-up 602 of functional material sheets (ISO,- TIM). One or more electrical isolation layers (ISO layers) 122 and one or more gap filling layers (TIM layers) 121 as described above with respect to Figures 1 to 5 may be layed- up.

[0188] The method comprises Lamination 603 in a PCB press.

[0189] The method comprises Surface finishes 604 (e. g. metals for solder, solid state lubricants for gliding).

[0190] The method comprises Separation 605 by sawing. Multiple heat dissipation assemblies 100a as described above with respect to Figures 1 to 5 may be produced.

[0191] The method comprises assembly 606 on PCB / housing / heatsink, e.g., PCB 113 and heat sink 115 as described above with respect to Figures 1 to 5.

[0192] Finally, a heat dissipating device 600 is produced that may correspond to one of the heat dissipating devices 100b, 200, 300, 400, 500 described above with respect to Figures 1 to 5.

[0193] Figure 7 shows a schematic diagram illustrating a method for producing a heat dissipating device 700 according to a second embodiment. The difference between the second embodiment and the first embodiment is the application of the metal layer 124 embedded in the isolation layer(s) 122.

[0194] The method comprises Provision 701 of a map-molded leadframe 601 (option a) or a molded panel 601 (option b).

[0195] The method comprises Lay-up 702 of functional material sheets (ISO,- TIM). One or more electrical isolation layers (ISO layers) 122 and one or more gap filling layers (TIM layers) 121 as described above with respect to Figures 1 to 5 may be layed- up. One or more metal layers 124 may be layed-up between two isolation layers 122.

[0196] The method comprises Lamination 703 in a PCB press.

[0197] The method comprises Surface finishes 704 (e. g. metals for solder, solid state lubricants for gliding).

[0198] The method comprises Separation 705 by sawing. Multiple heat dissipation assemblies 100a as described above with respect to Figures 1 to 5 may be produced.

[0199] The method comprises assembly 706 on PCB / housing / heatsink, e.g., PCB 113 and heat sink 115 as described above with respect to Figures 1 to 5.

[0200] Finally, a heat dissipating device 700 is produced that may correspond to one of the heat dissipating devices 100b, 200, 300, 400, 500 described above with respect to Figures 1 to 5.

[0201] Figure 8 shows a schematic diagram illustrating a method for producing a heat dissipating device 800 according to a third embodiment. Figure 8 illustrates a lamination onto existing singulated packages (mostly for leaded or no-lead board mounted packages). The method comprises provision 801 of compound sheet 810. This compound sheet 810 may comprise a multi-layered thermal interface compound 120 as described above with respect to Figures 1 to 5 which is protected upside and downside by two protective liners 811. The multi-layered thermal interface compound 120 comprises an electrical isolation layer 122 and an electrical isolation layer 121 as described above with respect to Figures 1 to 5 with a laminated interface 123 between the two layers 122, 121. The liner 811 on the downside can be removed for the following processing.

[0202] The method comprises pick and place 802 devices and sheets into jig 812.

[0203] The method comprises Cure 803 sheet to device with pressure & heat (p,T).

[0204] The method comprises Reflow 804 devices to board. The enhanced power packages 100a as described above with respect to Figures 1 to 5 are placed on a PCB 113

[0205] The method comprises remove 805 liner 811. This is the second liner 811 of the compound sheet 810 not yet removed during the provision 801 of the compound sheet 810.

[0206] The method comprises mount 806 onto heating or into housing. The enhanced power packages 100a onto PCB 113 are mounted on a heat sink 115 (or into a housing) as described above with respect to Figures 1 to 5.

[0207] Finally, a heat dissipating device 800 is produced that may correspond to one of the heat dissipating devices 100b, 200, 300, 400, 500 described above with respect to Figures 1 to 5.

[0208] The solution described in this disclosure can be applied in SMT (surface mount technology) devices. The integrated multilayer isolating TIM 122 can be soldered to a PCB board 113 using a levelling plate or jig during reflow, or using an SMA adhesive that tacks the SMD components in a levelled position on the PCB board 113.

[0209] The PCB board 113 with the levelled SMD components can then be mounted onto a heatsink 115 or into a housing with heatsink function, without additional placement of TIM, pads, pastes, etc. The assembly process can be fully automated and does not need to involve manual handling of delicate sheet material for isolation or thermal gap filling.

[0210] Products provided by such processing can be board assemblies with mounted heatsinks or PCB boards which are mounted onto heatsinks or into housings with heatsink function. For example, a PV (photo-voltaic) optimizer and other products. The solution described in this disclosure can be applied to board mounted power with top side cooling, but also power modules in PV, ICT (information and communication technology), automotive.

[0211] The solution described in this disclosure has the following benefits.

[0212] The number of non-positive thermally imperfect interfaces within the thermal path of a power electronic assembly can be reduced by increasing the number of void-free cured positive connection interfaces.

[0213] An electrically isolating thermal interface material for >600 V can be provided by vertically splitting of functions which is not limited to: gap filling, electrical isolation, thermal conduction, shielding against EMI, gliding layers for stress release, field grading, etc. In order to facilitate manufacturability, in one embodiment only one non-positive interface remains, that has to be joined during the final assembly. All other interfaces are cured / bonded internal interfaces, that are part of the package, or part of the assembly.

[0214] The isolation film can be bonded on at least one of the main faces to the gap filling layer by means of a cured positive connection, using a lamination process that uses the intrinsic resin system of the insulation film.

[0215] The other main face of the isolation film can be either bonded (cured positive connection) to; a) a shieldig or field grading layer, followed by another isolation film, followed by one of the next options; b) the source or drain area contact of a power semiconductor package or module; or c) the heat sink or metallic lid of the enclosure / housing.

[0216] The gap filling layer (compliance layer) is allowed to be electrically conductive, which allows choosing elastic materials with highest thermal conductivity.

[0217] The thin isolation film can be protected against mechanical wear and scratches / particle imprint by the elastic gap filling layer, and can thus be reduced in thickness without risk of damage during production.

[0218] Embedding of shielding layer (e. g. copper foil) in combination with through-package vertical connection allows implementation of EMI shielding against common mode conducted emission, or field grading function to enhance isolation density.

[0219] The solution presented in this disclosure can not only be applied to PV MPPT optimizers, but also to any kind of equipment that relies on cooling of SMT devices.

[0220] The solution presented in this disclosure may be scaled to molded power modules - both SSC (single side cooled) or DSC (dual side cooled) by means of the lamination process as described above with respect to Figures 6 to 8. In such case, the module does not need to provide isolation, it can be based on a simple leadframe. The isolation can be provided by applying the multi-layered thermal interface compound as described in this disclosure.

[0221] The solution presented in this disclosure may be applied to PCB embedded power devices such that PCB areas dedicated for cooling, that comprise e. g. thermal vias, Cu inlays or other large -metallized area that need to be cooled. They can be enhanced by the multilayer isolating TIM, e.g., the multi-layered thermal interface compound as described in this disclosure. The PCB board with embedded power devices can then be readily clamped to a heatsink with lowest isolation coordination effort.

[0222] While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other. Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

[0223] Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence. Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the disclosure beyond those described herein. While the disclosure has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the disclosure. It is therefore to be understood that within the scope of the appended claims and their equivalents, the disclosure may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1. A heat dissipating assembly (100a) mountable between a circuit board (113) and a heat sink (115), the heat dissipating assembly (100a), comprising: a power package (110) mountable on the circuit board (113), the power package (110) comprising a heat dissipation interface (111) arranged at a main surface (117) of the power package (110), the main surface (117) opposite to the circuit board (113); and a multi-layered thermal interface compound (120) mounted onto the heat dissipation interface (111) of the power package (110); wherein the multi-layered thermal interface compound (120) comprises: a thermally conductive electrical isolation layer (122); and a thermally conductive elastic gap filling layer (121); wherein the electrical isolation layer (122) is electrically isolating, thereby enabling the elastic gap filling layer (121) to be electrically conductive or at least being composed of electrically conductive parts.

2. The heat dissipating assembly (100a) of claim 1, wherein the thermally conductive electrical isolation layer (122) is configured to electrically isolate the heat sink (115) against an electrical potential of the heat dissipation interface (111) of the power package (110); and wherein the elastic gap filling layer (121) is configured to fill the gaps between the heat sink (115) and the electrical isolation layer (122).

3. The heat dissipating assembly (100a) of claim 1 or 2, wherein the multi-layered thermal interface compound (120) is configured for the following functionalities: heat transfer, electrical isolation, gap filling, electrical shielding, gliding and field grading.

4. The heat dissipating assembly (100a) of any of the preceding claims, wherein the electrically conductive parts of the elastic gap filling layer (121) have a higher thermal conductivity than the electrical isolation layer (122).

5. The heat dissipating assembly (100a) of any of the preceding claims, wherein the elastic gap filling layer (121) is configured to protect the electrical isolation layer (122) from mechanical damage.

6. The heat dissipating assembly (100a) of any of the preceding claims, wherein the electrical isolation layer (122) comprises a curable organic or polymer compound with thermal conductivity enhancing, electrically non-conductive fillers comprising at least one of the following: Boron nitride, Aluminum nitride, aluminum oxide, silicon oxide, silicon nitride and Silicon carbide.

7. The heat dissipating assembly (100a) of any of the preceding claims, wherein the gap filling layer (121) comprises polymer matrix composites with electrically conductive or electrically non-conductive thermal conductivity enhancing fillers.

8. The heat dissipating assembly (100a) of claim 7, wherein the thermal conductivity enhancing fillers of the polymer matrix comprise at least one of the following: metals, graphite, graphene, CNTs, carbon fibers, functionalized forms of graphite, graphene, CNTs, or carbon fibers, aluminum oxide, Boron nitride, Aluminum nitride and Silicon carbide.

9. The heat dissipating assembly (100a) of any of the preceding claims, wherein the power package (110) comprises a package body (114) made of a molding material; wherein the heat dissipation interface (111) of the power package (110) is exposed at the main surface (117) from the molding material of the package body (114); and wherein the electrical isolation layer (122) fully covers the exposed heat dissipation interface (111) of the power package (110).

10. The heat dissipating assembly (100a) of any of the preceding claims, wherein the multi-layered thermal interface compound (120) comprises one or more electromagnetic interference, EMI, shielding layers (124) and / or field grading material, FGM, layers (124) embedded inside the electrical isolation layer (122); wherein the one or more EMI shielding layers (124) are configured to shield the power package (110) from electromagnetic interference; and wherein the one or more FGM layers (124) are configured to reduce an electric field strength near the electrical isolation layer (122).

11. The heat dissipating assembly (100a) of claim 10, wherein the one or more EMI shielding layers (124) comprise of one or more of the following: structured metal sheets or foils of Cu, Ni, Al, Au, Ag, Fe; structured sheets or foils of carbon-based materials, carbon fibers, carbon nanotubes, nanographene, graphite and / or graphene; composite polymeric materials with metal and / or carbon fillers including nano or microparticles, sheets, wires and nets.

12. The heat dissipating assembly (100a) of claim 10 or 11,wherein the one or more FGM layers (124) comprise of polymer-based isotropic or non-isotropic or layered composites with one or more fillers; wherein the fillers comprise at least one of the following:Strontium Titanate, graphite, Barium Titanate, Zinc Oxide, Aluminum Oxide, Iron Oxide, metal or carbon fillers as nano or microparticles, sheet or wires.

13. The heat dissipating assembly (100a) of any of claims 10 to 12, wherein the one or more EMI shielding layers and / or FGM layers are electrically connected to a through-package contact (118) of the power package (110) electrically connecting the EMI and / or FGM layers to a pre-defined electrical potential of a pad (119) of the circuit board (113).

14. The heat dissipating assembly (100a) of any of the preceding claims, wherein the multi-layered thermal interface compound (120) comprises a gliding layer (401) arranged between the gap filling layer (121) and the heat sink (115); wherein the gliding layer (401) is configured to provide an elastic, non-locking and / or friction-reducing interface between the gap filling layer (121) and the heat sink (115).

15. The heat dissipating assembly (100a) of claim 14, wherein the gliding layer (401) comprises of one ormore of the following: graphite, graphene, PTFE, Silicone, or other dry solid-state lubricants.

16. The heat dissipating assembly (100a) of any of the preceding claims, wherein the multi-layered thermal interface compound (120) comprises a second elastic gap filling layer (121b) mounted between the isolation layer (122) and the heat dissipation interface (111) of the power package (110); wherein the second elastic gap filling layer (121b) is configured to fill the gaps between the heat dissipation interface (111) of the power package (110) and the electrical isolation layer (122).

17. The heat dissipating assembly (100a) of claim 16, wherein the second elastic gap filling layer (121b) is configured to protect the electrical isolation layer (122) and the power package (110) from mechanical damage.

18. The heat dissipating assembly (100a) of any of the preceding claims, wherein an interface between the thermally conductive electrical isolation layer (122) and the elastic gap filling layer (121) forms a cured positive connection.

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