Method for attaching a terminal to a metal substrate structure for a semiconductor power module and semiconductor power module

Abstract

A method for attaching a terminal (4) to an insulated metal substrate structure (3) for a semiconductor power module (10) includes providing at least one terminal (4) and providing on the insulated metal substrate structure (3) a metal top layer (17), a metal bottom layer (19), and an insulating resin layer (18) disposed between the metal top layer (17) and the metal bottom layer (19). The method further includes providing a sintering layer (5) to form a sintering region of the at least one terminal (4) and bonding the sintering layer (5) to the metal top layer (17) and / or the at least one terminal (4). The method further includes bonding the at least one terminal (4) to the metal top layer (17) by sintering using a sintering tool (6) such that the sintering layer (5) is disposed between the metal top layer (17) and the at least one terminal (4) to connect the at least one terminal (4) to the metal top layer (17).

Description

Technical Field

[0001] The present disclosure relates to a method for attaching terminals to an insulated metal substrate structure of a semiconductor power module. The present disclosure further relates to a semiconductor power module.

Background Art

[0002] Conventional insulated metal substrates form a technology for low and medium power semiconductor packages having both low insulation requirements and low heat resistance requirements. Terminals are attached to the insulated metal substrate, and a highly reliable and cost-effective connection of the terminals on the insulated metal substrate is required.

Summary of the Invention

Means for Solving the Problems

[0003] Embodiments of the present disclosure relate to a method for attaching terminals to a metal substrate structure that can contribute to a low-cost semiconductor power module and enables a reliable function also for high-voltage power module applications with enhanced reliability requirements. Further embodiments of the present disclosure relate to corresponding semiconductor power modules.

[0004] According to one embodiment, a method for attaching terminals to an insulated metal substrate structure for a semiconductor power module includes providing at least one terminal and providing, on the insulated metal substrate structure, a top metal layer, a bottom metal layer, and an insulating resin layer disposed between the top metal layer and the bottom metal layer. The method further includes providing a sintering layer to form a sintering region of the at least one terminal and bonding to the upper surface of the top metal layer and / or the bottom surface of the at least one terminal. The method further includes bonding the at least one terminal to the top metal layer by sintering using a sintering tool such that the sintering layer is disposed between the top metal layer and the at least one terminal and the at least one terminal is connected to the top metal layer.

[0005] By the method described, it is possible to realize a sintered joint connection on an insulated metal substrate that can contribute to the stable and reliable function of a semiconductor power module even for high-voltage power module applications. The method further contributes to reliably attaching terminals on the insulated metal substrate by sintering while reducing, for example, the risk of damage to the insulating resin layer. The insulated metal substrate structure realizes a cost-effective technology for power semiconductor modules having low insulation and low thermal resistance requirements, enabling large power modules for applications in low, medium, and high voltage ranges. The method described can also contribute to the realization of a sintered joint connection on a metal substrate structure that enables the stable and highly reliable function of a semiconductor power module having such a metal substrate.

[0006] The finding in the context of the present disclosure is that alternative joining techniques such as welding techniques can provide highly reliable joint connections, but are considered critical with respect to a stable process on a substrate having an insulating resin sheet that does not damage the substrate structure. In particular, ultrasonic welding involves a strong impact of thermal and mechanical stresses on the substrate structure due to the large friction and pressure between the terminal leg and the substrate. Here, the resin sheet, which is clearly softer than ceramic but also fragile because it contains inorganic fillers, is strongly at risk of deformation and crack formation. Corresponding deformation of the underlying soft layer can occur in the ultrasonic welding process, for example, for an ultrasonically joined thick copper wire on a thin soldered copper small plate. The soft solder layer under the copper wire undergoes strong deformation similar to the soft resin sheet of the insulated metal substrate when welding the terminal leg on it.

[0007] The ultrasonic welding experiment on the insulated metal substrate confirms these expectations that significant damage occurs to the insulating resin sheet during the welding process, and as a result, ultrasonic welding on the insulated metal substrate is considered very difficult or even impossible. At least, there is a non - negligible risk that the interface of the insulating resin sheet contains defects under the welding terminal legs due to the welding technique. Additionally, laser welding or other welding techniques can also be considered fatal regarding damage to the substrate, especially the resin sheet, due to strong thermal shock and the introduced mechanical stress. The resin sheet is very dangerously exposed to deformation and crack formation. Also, there is a risk of the metallization peeling off from the resin sheet layer. When applying ultrasonic welding or laser welding, or other welding techniques for the terminal legs to the circuit metallization of the insulated metal substrate, the corresponding failure modes may occur.

[0008] By using the described method for manufacturing a metal substrate structure having one or more sintered terminals, it is possible to counteract the aforementioned adverse effects caused by the sintering of the terminals and the metal top layer. The sintering process enables reducing the mechanical and thermal stresses acting on the lower layer of the metal substrate structure. It is possible to reduce the risk of crack or damage formation in the resin layer and peeling of the metal top layer, enabling the realization of a stable semiconductor power module that can function reliably, for example, in high - voltage power module applications in the voltage range from 0.5 kV to 10.0 kV.

[0009] According to one embodiment of the present method, providing a sintered layer and bonding involves providing a substance having predetermined sintered particles and depositing the substance, for example, by printing on the upper surface of the metal top layer, thereby forming a sintered region having a preformed sintered layer. The depositing includes depositing the substance which, for example, represents a sintering raw material in the form of a film or paste that can be printed at a predetermined position on the metal top layer. The sintering material, and thus the sintered layer, can be provided in a predetermined manner as a pumpable liquid or viscous paste containing at least one of silver, copper, gold, and nickel, or other applicable metals as the main material. Alternatively or additionally, the sintering raw material can be provided as a solid sheet or preform attached to the substrate and / or terminals. Alternatively or additionally, the sintering material may be another material that can be deposited by sintering. The sintering raw material can be pre-deposited at a given position on the insulating metal substrate structure so as to have the created structure.

[0010] The sintering material can include micrometer and / or nanometer particles of the main component that enable the formation of a firmly or substantially joined connection between one or more terminals and the metal top layer. The sintered layer or the sintering material for forming the sintered layer can include a material composition containing polymers and / or solvents, binders or agents in the raw material that are removed during the sintering process. Considering the sintered connection between one or more terminals and the insulating metal substrate structure, the sintered layer typically realizes a more or less porous paste of a pure metal having a more or less porous shape distinguishable from the materials of the terminals and the metal top layer that can be realized by bulk copper or aluminum.

[0011] Sintering realizes a process of compressing and forming a solid mass of a material by heat and / or pressure without melting the mating part to its melting point. A sintering tool can be used to apply pressure and / or heat to the terminal to sinter the terminal and the metal top layer together with the sintering layer therebetween. Thus, sintering can be described as firing particles together, while bonding is performed by a diffusion process between the particles.

[0012] According to a further embodiment of the method, sintering is performed at a high pressure of up to 20 MPa acting on at least one terminal. For example, the high pressure is set in the range from 5 MPa to 25 MPa. For example, sintering of the terminal and the metal top layer can be performed at a high pressure of up to 10 MPa or 15 MPa. Usually, a relatively high pressure acting on the mating part also depends on the porosity of the sintered material and enables a reliable quality of the sintered joint. In this case, the sintering layer has low porosity and / or high density. Thus, the pressure used for sintering is provided in cooperation with the mating part and the selected sintered material.

[0013] According to a further embodiment of the method, sintering is performed at a low pressure of up to 2 MPa acting on at least one terminal. For example, sintering of the terminal and the metal top layer can be performed at a low pressure of 0.2 MPa, 0.5 MPa, 1 MPa or 1.5 MPa. The selection of the sintering pressure also depends on the sensitivity of the mating part to pressure. In this case, especially the resin sheet of the substrate is sensitive. For example, one or more terminals belong to an electronic device such as a chip, and high pressure should not be used to reduce the risk of damaging the chip and / or the resin layer. When low pressure is used for sintering, the terminal can be fixed or held in place using a rubber or positioning tool that may also belong to the sintering tool. Moreover, sintering of the terminal and the metal top layer can be performed without applying pressure so that no additional pressure or a very low pressure is used during sintering.

[0014] According to a further embodiment of the method, providing at least one terminal includes providing a given stress relief structure to the at least one terminal. The stress relief structure can include at least one of a spring structure, a thin portion, and a recess implemented on one or more terminals to beneficially affect the sintering process.

[0015] According to a further embodiment of the method, providing at least one terminal includes providing one or more terminals coupled to a housing block and / or a lead frame. The terminals can be coupled or directly connected to the lead frame or the housing block. The method can further include coupling the housing block and / or the lead frame to the metal substrate structure using the terminals such that a predetermined pressure for sintering is applied by the coupling and acts on the plurality of terminals. Thus, the sintering pressure can be applied by the coupled housing block itself. Nevertheless, pressure can be applied to the terminal legs of each terminal to contribute to a reliable sintering process.

[0016] The one or more terminals can be made of or include at least one of copper, copper alloy, aluminum and aluminum alloy, or any other applicable metal or other conductive material. The metal top layer can also be made of or include at least one of copper, copper alloy, aluminum and aluminum alloy, or any other applicable metal or other conductive material.

[0017] According to a further embodiment of the method, a coating layer is provided on the upper surface of the metal top layer configured to face the sintering material or the bottom surface of at least one terminal during sintering. Alternatively or additionally, at least one terminal is provided with a coating layer on the bottom surface configured to face the sintering layer or the metal top layer of the metal substrate structure during sintering. Such a coating may be intended to facilitate the bonding connection between the terminal, the sintering material, and / or the substrate metallization realized by the metal top layer.

[0018] One or more of the aforementioned coating layers of the terminal and the metal top layer can be made of or include noble metals such as nickel and / or silver and / or gold, and / or one or more other metals. Such a coating can contribute to preventing oxidation and / or improving the conditions of the sintering process, and / or can also protect the resin layer of the metal substrate structure. Each coating can partially or completely cover a predetermined surface of the bottom surface of the terminal or the upper surface of the metal top layer. Moreover, each coating may include one or more layers.

[0019] The insulating resin layer can be realized as a prepreg sheet assembled between the upper and lower two metal plates forming the metal top layer and the metal bottom layer to form a dielectric layer. Such a metallization sheet or plate is joined to the dielectric resin layer, for example, by a lamination process. Subsequently, the required metallization structure of the metal top layer can be made by subsequent steps of masking and etching processes for locally removing the conductive metal to create the final metallization structure. Alternatively, the upper metallization structure can be formed, for example, by cutting or stamping before the formation of the completed metal substrate structure.

[0020] Alternatively, the resin layer can be formed by molding. For such a molded dielectric layer, the molding material realizes a pumpable molding material having predetermined material properties. The molding material is a liquid or viscous raw material of the resin layer to be formed. For example, the molding material is an epoxy and / or ceramic-based liquid. Alternatively or additionally, the raw material of the dielectric layer may be a thermosetting or thermoplastic resin material such as polyamide, PBT, or PET. Alternatively or additionally, the raw material of the dielectric layer may include an inorganic filler based on a ceramic material, for example, for improved thermal conductivity and / or CTE adjustment with respect to the metal top layer and / or the metal bottom layer. For example, the molded dielectric layer includes a resin-based dielectric material having a ceramic filling material, such as Al2O3, AlN, BN, Si3N4, or SiO2. For example, the dielectric layer is an epoxy containing a filler. The dielectric layer can also be based on other applicable molding techniques such as transfer, injection, or compression molding, or other materials such as bismaleimide, cyanate ester, polyimide, and / or silicone. Alternatively or additionally, the dielectric layer can include a ceramic material and / or a hydroset material, or a combination of two or more of the aforementioned components.

[0021] By aligning the positions of the metal top layer and the metal bottom layer with respect to each other with a predetermined distance therebetween, the subsequent thickness of the molded dielectric layer is substantially predetermined. For example, the thickness is defined along the stacking direction of the metal substrate structure that may exhibit the z direction. However, for example, for proper positioning of the metal pattern with respect to the x and y directions, the positions can also be aligned in the perpendicular x and y directions. For example, the alignment of the positions can be achieved by placing the metal top layer on a release film or liner, or by another fixation within a mold chase of a molding tool, for example. This enables precise positioning of the provided metallization structure of the metal top layer with respect to the metal bottom layer, which can be useful, for example, when the metal top layer includes separate metal pads due to different operating potentials. In the case of lamination, the thickness of the resin layer is given by the thickness and behavior of the laminated layers.

[0022] The thickness of the insulating resin layer can have a value ranging from 50 μm to 300 μm. The thickness of the topmost metal layer can have a value ranging from 0.15 mm to 0.5 mm, or up to 2.00 mm. The terminal can have an L-shaped configuration having a long and narrow terminal body mainly extending in the stacking direction and a terminal leg portion mainly extending in a lateral direction substantially perpendicular to the stacking direction. The terminal leg portion can form a plate having a thickness ranging from 0.5 mm to 1.5 mm with respect to the stacking direction. The thickness of the terminal leg portion and / or the sintered region formed by the sintering process may be, for example, smaller compared to other parts of the terminal. For example, the lateral size or area of the terminal leg portion may be larger or smaller than the corresponding extent of the sintered layer.

[0023] One or more terminals can realize a main terminal for power connection of a semiconductor power module, or an auxiliary terminal for electrical signal connection or signal wiring.

[0024] At least one terminal can also include a structure created to improve sintering. Such a sintering structure can be realized, for example, by one or more slots, grooves, and / or recesses within the terminal leg portion of the terminal, or by a roughened or thinned region. Such a sintering structure can be created on the upper surface and / or bottom surface of each terminal, and / or on the upper surface of the topmost metal layer. A specific terminal structure can beneficially affect the sintering process and contribute to the formation of a sintered joint that joins substantially or firmly.

[0025] By using the described manufacturing or attachment method for joining the terminal to the insulated metal substrate, it is possible to counteract adverse effects. For example, it is possible to reduce the risk of formation of cracks, deformations or other damages, particularly in the insulating resin layer of the metal substrate structure, and a stable semiconductor power module that can improve durability or lifespan and ensure the proper functioning of the semiconductor power module can be realized at low cost.

[0026] Finally, it is pointed out that all the features and methods proposed can be used alone, but combinations of two or more can also be used.

[0027] According to one embodiment, a semiconductor power module includes a substrate having a top metal layer, a bottom metal layer, and an insulating resin layer bonded to both the top metal layer and the bottom metal layer and disposed between these layers. The semiconductor power module further includes at least one terminal and a sintered layer. The sintered layer is disposed between the top metal layer and at least one terminal with respect to the stacking direction of the semiconductor power module. The sintered layer connects the bottom surface of at least one terminal to the top surface of the top metal layer by sintering.

[0028] As a result of being able to manufacture the described semiconductor power module according to the embodiments of the method, the features and characteristics of the method are also disclosed with respect to the semiconductor power module, and vice versa. Therefore, the present disclosure includes several aspects, and all features described with respect to one aspect are also disclosed herein with respect to other aspects, even if each feature is not explicitly mentioned in the context of a particular aspect.

[0029] According to one embodiment of the semiconductor power module, at least one terminal includes a given stress relaxation structure having at least one of, for example, a spring structure, a thin portion, and a recess. Therefore, each terminal can have a spring section or an elastic portion that realizes a buffer or stress relaxation structure that can contribute to the protection of the resin layer against mechanical and / or thermal shock.

[0030] According to a further embodiment, the semiconductor power module includes a plurality of terminals that are coupled on one hand to a housing block and / or a lead frame and on the other hand are each connected to the top surface of the top metal layer by sintering. The housing block can be formed as a resin body, and the plurality of terminals can be partially embedded in the resin body.

[0031] The semiconductor power module can further include a heat sink coupled to the metal bottom layer of the metal substrate structure to dissipate heat during operation of the semiconductor power module. The metal bottom layer forms the base of the metal substrate structure and can be made of or include copper, aluminum, and / or corresponding alloys. Thus, the semiconductor power module can include a separate heat sink. The additional heat sink can also be made of copper, aluminum and / or corresponding alloys, or a composite material such as aluminum-silicon-carbide or magnesium-silicon-carbide. Alternatively or additionally, the metal bottom layer of the metal substrate structure can itself act as a heat sink and can be configured, for example, to have ribs, fins, or protrusions on the bottom surface with respect to the stacking direction to provide beneficial heat dissipation. The metal bottom layer can further act as the base plate of the semiconductor power module.

[0032] A semiconductor power module including a metal substrate structure can be further partially or completely encapsulated by a resin or dielectric gel created by molding or potting. Further, the semiconductor power module can include two or more embodiments of the buffer structure described above. The semiconductor power module can further include electronic devices, such as chips, integrated circuits, sensors and / or other individual devices.

[0033] The proposed process of sintering terminal legs on the surface of an insulated metal substrate structure has strong potential to reduce the mechanical and thermal shocks of the bonding process to a resin insulation sheet, for example, compared to welding techniques. A sintering process that does not damage the heat-sensitive and pressure-sensitive resin layer is possible, making the use of this relatively cost-effective substrate technology interesting. Such an attachment or manufacturing method for an insulated metal substrate structure can be interesting for large power modules with enhanced reliability requirements and power modules in high voltage classes. However, the described method enables the production of metal substrate structures and semiconductor power modules that can be applied not only to various miscellaneous products, such as low voltage industrial and automotive products operating in a voltage range of 1.7 kV or less, but also to products in higher voltage classes. Substantial cost reduction can be possible when replacing the standard configuration of a ceramic substrate soldered to a base plate with an insulated metal substrate. On the one hand, the material cost can be reduced, and on the other hand, some other process steps, such as the bonding process between the substrate and the base plate in a power module assembly, are not required and can be removed from the process flow.

[0034] Exemplary embodiments will be described below with reference to schematic diagrams and reference numerals.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0036] The accompanying drawings are included to provide a further understanding. It should be understood that the embodiments shown in the drawings are exemplary representations and are not necessarily drawn to scale. The same reference numerals indicate elements or components having the same function. As long as the elements or components correspond to each other with respect to their functions in different figures, the description thereof for each of the following figures will not be repeated. For clarity, elements may not be labeled with corresponding reference numerals in all figures.

[0037] FIG. 1 shows a side view of an embodiment of a method step for attaching a terminal leg or terminal 4 to an insulated metal substrate structure 3 of a semiconductor power module 10 for a semiconductor device. The semiconductor power module 10 includes an insulated metal substrate structure 3 having a metal top layer 17, a metal bottom layer 19, and an insulating resin layer 18 disposed between the metal top layer 17 and the metal bottom layer 19 in a stacking direction A.

[0038] The semiconductor power module 10 further includes a cooler or heat sink 1 having a fin or rib structure coupled to the metal substrate structure 3 by a bonding layer 2 and / or a layer of thermal interface material. With respect to the illustrated stacking direction A, one or more terminals 4 will be coupled to the metal top layer 17 and will be coupled to the metal bottom layer 19 via the bonding layer 2 under the heat sink 1.

[0039] In this regard, terms such as "above", "under", "top", "upper", and "bottom" refer to the orientation or direction as shown in the figure and with respect to the stacking direction A. Thus, the height or thickness of the described elements is related to the stacking direction A, while the lateral direction B is oriented perpendicular to the stacking direction A (see FIGS. 1 to 3).

[0040] The thickness of the insulating resin layer 18 can be, for example, 100 to 200 μm. The thickness of the circuit metallization formed by the top metal layer 17 can be 0.15 to 2.00 mm. The thickness of the bottom metal layer 19 that can realize the base plate can be 1 to 5 mm, and it can also be configured to dissipate heat from the metal substrate structure 3 and the semiconductor power module 10. The resin layer 18 can contain an epoxy resin material, but other types of resins such as other thermosetting resins or thermoplastic resins are also possible. The resin layer 18 may be formed as a resin sheet, or may be formed as a prepreg sheet assembled or laminated between the two metal layers 17 and 19.

[0041] Alternatively or additionally, the metal substrate structure 3 includes a resin layer 18 formed by molding, for example, by injection, transfer, or compression molding. The resin of the resin layer can contain an inorganic filler, a ceramic material, for example, AlN, Si3N4, BN, Al2O3, or SiO2. The bottom metal layer 19 can be made of or contain copper and / or aluminum and / or corresponding alloys. The circuit metallization formed by the top metal layer 17 can be made of or contain copper and / or aluminum and / or corresponding alloys. Moreover, the top metal layer 17 may be partially or completely coated, and the corresponding coating of the circuit metallization can be made of or contain noble metals such as nickel and / or gold and / or silver, and / or other metals.

[0042] The semiconductor power module 10 can include silver or copper and further includes a sintered layer 5 disposed between the metal top layer 17 and at least one terminal 4. The sintered layer 5 is used to connect the bottom surface 42 of the terminal 4 to the upper surface 171 of the metal top layer 17 by sintering. The sintered layer 5 can have a thickness of 20 μm to 50 μm, and further up to 250 μm. The sintered layer 5 can be formed thinner from the perspective of cost reduction and can be pre-deposited on one or both of the mating partners.

[0043] Sintering enables the main or auxiliary terminal 4 to be joined not only to the insulated metal substrate structure 3 but also to a corresponding substrate structure based on an alternative technique such as a punched and formed metal substrate. In contrast to welding techniques where strong thermal and / or mechanical shocks make the joining process very difficult, when joining the terminal leg to the circuit metallization or the metal top layer 17 by sintering, only a moderate impact of static mechanical pressure and a moderately elevated temperature need to be considered.

[0044] As shown in FIGS. 1 to 3, one or more terminal legs can be joined to the upper surface 171 of the insulated metal substrate structure 3 by a sintering process. The pressure and / or heat for performing the sintering process can be applied, for example, by a sintering tool 6 acting on the upper surface 41 of the terminal 4. However, heat can also be applied to the entire insulated metal substrate structure 3 and the assembly setup for manufacturing the semiconductor power module 10. The sintering tool 6 can further enable the precise positioning or holding of the terminal 4 in a given position during the sintering process. The sintered connection is provided by a sintering material configured to form a sintered layer 5 having particles of silver, copper, or any other material applicable to the sintering process with a micron or sub-micron size.

[0045] The sintering process can be used for a single terminal 4 or a group consisting of a plurality of terminals. Also, a simultaneous sintering process of a plurality of terminals arranged on a common terminal or a housing block or a lead frame is possible (see Fig. 3). In order to cancel out the mechanical stress applied to the bonding connection part and contribute to the improvement of reliability, for further improvement, the terminal 4, for example, for the purpose of compensating for possible vibrations or differences in the coefficient of thermal expansion, or for compensating for mechanical or geometric tolerances in the housing block or terminal structure without strengthening the stress, can have a stress relaxation structure 7 (see Fig. 2).

[0046] The terminal 4 can be made of or include copper, aluminum, and / or corresponding alloys, and can realize the main terminals or auxiliary terminals of the semiconductor power module 10. Moreover, the terminal 4 can be provided with a coating layer that partially or completely covers the upper surface 41 and / or the bottom surface 42 of the terminal 4. Such a coating layer can beneficially affect the sintering process and / or protect the surface of the terminal 4 from oxidation, and can be made of or include precious metals such as nickel, gold, silver, and / or other metals. The coating can also include one or a plurality of layers of such materials.

[0047] The steps of the method for attaching the terminal 4 to the metal substrate structure 3 can follow the flowchart shown in Fig. 4. In step S1, at least one terminal 4 is provided. A terminal 4 provided with one or a plurality of coating layers on its upper surface 41 and / or bottom surface 42 can be provided.

[0048] In step S2, the metal substrate structure 3 is provided with a metal top layer 17, a metal bottom layer 19, and an insulating resin layer 18 arranged therebetween. The coating layer can also be at least locally available on the upper surface 171 of the metal substrate structure 3.

[0049] In step S3, a sintering material can be provided to form the sintered layer 5. For example, the sintering material includes fine particles and / or nanoparticles containing silver and / or gold provided as a substance or raw material. Next, the sintering material can be deposited on the upper surface 171 of the metal top layer 17 and / or the bottom surface 42 of the terminal 4 by printing, so as to form a sintering region intended to form the sintered layer 5. The sintering material may also be a solid sheet or preform attached to one of the mating partners.

[0050] In a further step S4, the terminal 4 is pressed towards the metal top layer 17 by a given pressure, and heating of the assembled terminal 4, the metal top layer 17 and the sintering material therebetween is started. In this regard, the given pressure and heat can be applied simultaneously, or the pressure can be applied before or after introducing the heat into the setup. For example, preheating can be carried out before entering the sintering press. Such a preheating process can introduce a temperature setting slightly lower than the temperature used during the sintering process.

[0051] Thus, so to speak, the sintering material is fired and converted into a sintered layer 5 that connects the bottom surface 42 of the terminal 4 to the upper surface 171 of the metal top layer 17 by sintering.

[0052] One or more terminals 4 can realize main terminals or auxiliary terminals and are joined to the upper surface 171 of the insulating metal substrate 3 by sintering by means of their terminal legs. The sintered connection between the terminal legs and the upper surface 171 is made from particles of silver, copper, or other materials applicable to the sintering process. The described sintered particles can have a diameter in the micron or submicron range. Depending on the type and material of the terminal, the terminal legs have a thickness of 0.5 - 1.5 mm. For an improved sintering process or protection against, for example, oxidation of the mating partner, the upper surface 171 of the substrate and / or the upper surface 41 and / or the bottom surface 42 of the terminal legs may be coated with a metal layer made of, for example, nickel, silver and / or gold.

[0053] There can be several setups of terminals 4 mounted on the upper surface 171 of the metal substrate structure 3. First, one or more single terminals 4 can be individually joined to the upper surface 171 by sintering. Second, a plurality of terminals 4 can be arranged and configured in groups, such as in the case of a lead frame, and the terminal legs are simultaneously joined to the substrate metallization realized by the metal top layer 17. Finally, simultaneous sintering of a plurality of terminals 4 arranged in a common terminal or housing block 8 is possible (see FIG. 3). Here, at least a part of some of the terminals 4 is embedded, for example, in the common resin body of the housing block 8. The housing block 8 can form part of the module housing of the semiconductor power module 10 created by a molding process. The continuous sintering process can also be carried out on the terminals of the lead frame or housing block.

[0054] Furthermore, one or more stress relaxation structures 7 can be implemented on one or more terminals 4 (see FIGS. 2 and 3). Such stress relaxation structures can contribute to compensating for thermal expansion, or vibration or other forces, or mechanical or geometric tolerances in the housing or terminal structure, without increasing the stress to which the bonding connection is exposed. The stress relaxation structure 7 for each terminal 4 can be realized by different designs, for example, one or more spring portions, thin portions, and / or openings / holes in the terminal shaft.

[0055] For example, in contrast to conventional bonding techniques using ultrasonic welding processes, sintering can reduce the mechanical and thermal shock to the resin separation layer 17. Additionally, one or more terminals 4 can be coupled to the metal top layer 17 by soldering, adhesion, dry contact, welding, and / or any other applicable bonding method used for fixing onto the circuit metallization realized by the metal top layer 17, for example, to form a very stable and highly reliable connection. The terminals 4 can also be coupled to the metal top layer 17 by sintering that pre-forms the metal substrate structure 3 to further prevent mechanical shock to the insulating resin layer 18.

[0056] For example, depending on the joining partner and / or the sintering material, there are several options for realizing the sintering process itself.

[0057] · Sintering can be processed at high pressure using a pressure of about 20 MPa or a pressure value from 5 MPa to 25 MPa.

[0058] · Sintering can be processed at low pressure using a pressure of about 0.5 MPa or a pressure value from 0.1 MPa to 5.0 MPa. In the case of a terminal or a housing block 8 in which a plurality of terminals 4 are arranged in a resin body that can be part of the module housing, the pressure may be applied by the housing block 8 itself.

[0059] · Pressureless sintering; · Heating can be processed at a temperature within the range from 200 to 270 °C, or up to 290 °C, or up to 300 °C.

[0060] Heating and heat maintenance can be realized by an oven, a hot plate, and / or a heat sintering tool for heating the sintering raw material and the joining partner from one or more sides. The pressure can be applied by a mechanical pressing element that can also be provided with a positioning and / or fixing structure formed in cooperation with each terminal design to be sintered. The sintering material can contain sintering particles of micrometers and / or nanometers, and larger particles can be used at a higher sintering pressure according to the porosity requirements and the intended use of the semiconductor power module 10.

[0061] For example, the sintering raw material is provided as a paste material having silver and / or copper particles of nanometer size. Then, a relatively low pressure ranging from 0.1 MPa to 5.0 MPa is applied, and heat is applied over a time range of 1 to 10 minutes or up to 20 minutes at a temperature of 200 to 300 °C, whereby the sintered layer 5 can be formed. Thus, alternatively or additionally, the paste material can contain silver and / or copper particles of micrometer size.

[0062] Alternatively, the sintering raw material can be provided, for example, as a silver and / or copper foil having silver and / or copper particles of micrometer size. Then, a relatively high pressure ranging from 5 MPa to 25 MPa is applied, and heat is applied over a time range of 1 to 10 minutes or up to 20 minutes at a temperature of 200 to 300 °C, whereby the sintered layer 5 can be formed. The selection of silver, gold, nickel or copper particles can be made according to cost, the sintering process and its temperature and pressure parameters, and / or the design and intended use of the semiconductor power module 10, and / or the requirements regarding the porosity of the sintered joint and the sintered layer 5.

[0063] The embodiments shown in FIGS. 1 to 2 described above represent exemplary embodiments of an improved metal substrate structure 3, a semiconductor power module 10 and a manufacturing method. Therefore, they do not constitute a complete list of all embodiments. The actual arrangement configuration and method can be different from the embodiments shown, for example, with respect to the metal substrate structure 3 and the semiconductor power module 10.

Explanation of Reference Signs

[0064] Reference Sign 1 Heat Sink 2 Bonding Layer 3 Metal Substrate Structure 4 Terminal 41 Upper Surface of Terminal 42 Bottom Surface of Terminal 5 Sintered Layer 6 Sintering Tool 7 Stress Relaxation Structure 8 Housing block 10 Semiconductor power module 17 Metal top layer 171 Upper surface of the metal top layer 18 Resin layer 19 Metal bottom layer A Lamination direction B Lateral direction S(i) Steps of a method for attaching a terminal to a metal substrate structure

Claims

1. A method for attaching a terminal (4) to an insulated metal substrate structure (3) for a semiconductor power module (10), comprising: providing at least one terminal (4); providing, on the insulated metal substrate structure (3), a top metal layer (17), a bottom metal layer (19), and an insulating resin layer (18) disposed between the top metal layer (17) and the bottom metal layer (19); providing a sintering layer (5) for forming a sintering region of the at least one terminal (4), and bonding the sintering layer (5) to the upper surface (171) of the top metal layer (17) and / or the bottom surface (42) of the at least one terminal (4); bonding the at least one terminal (4) to the top metal layer (17) by sintering such that the sintering layer (5) is disposed between the top metal layer (17) and the at least one terminal (4) and connects the at least one terminal (4) to the top metal layer (17); wherein providing and bonding the sintering layer (5) comprises: providing a substance or sintering raw material having predetermined sintering particles of micrometer size; depositing the substance or sintering raw material by printing onto the upper surface (171) of the top metal layer (17) to form the sintering region and preform the sintering layer (5); A method as described above.

2. A method for attaching a terminal (4) to an insulated metal substrate structure (3) for a semiconductor power module (10), comprising: providing a plurality of terminals (4) coupled to a housing block (8) and / or a lead frame; providing, on the insulated metal substrate structure (3), a top metal layer (17), a bottom metal layer (19), and an insulating resin layer (18) disposed between the top metal layer (17) and the bottom metal layer (19); providing a sintering layer (5) for forming a sintering region of each of the terminals (4), and bonding the sintering layer (5) to the upper surface (171) of the top metal layer (17) and / or the bottom surface (42) of each of the terminals (4); bonding each of the terminals (4) to the top metal layer (17) by sintering such that each sintering layer (5) is disposed between the top metal layer (17) and the associated terminal (4) and connects the terminal (4) to the top metal layer (17); including, coupling the terminal (4) includes coupling the housing block (8) and / or the lead frame to the insulated metal substrate structure (3) such that a predetermined pressure for sintering applied by the coupling acts on the plurality of terminals (4). Method. **Claim 3** providing the sintering layer (5), and coupling includes: providing a substance or sintering raw material having predetermined sintering particles; depositing the substance or sintering raw material by printing on the upper surface (171) of the metal top layer (17) to form the sintering region and preform the sintering layer (5). The method according to any one of the preceding claims, including. **Claim 4** The method according to any one of the preceding claims, wherein the sintering layer (5) includes at least one of silver, copper, gold, and nickel. **Claim 5** The method according to any one of the preceding claims, wherein sintering is performed at a maximum high pressure of 25 MPa acting on the at least one terminal (4). **Claim 6** The method according to any one of claims 1 to 4, wherein sintering is performed without pressure or at a maximum low pressure of 2 MPa acting on the at least one terminal (4). **Claim 7** providing the at least one terminal (4) includes: providing a given stress relaxation structure (7) to the at least one terminal (4), the stress relaxation structure (7) including at least one of a spring structure, a thin portion, and a recess. The method according to any one of the preceding claims, including. **Claim 8** providing the at least one terminal (4) includes: providing a plurality of terminals (4) coupled to a housing block (8) and / or a lead frame. The method according to any one of the preceding claims. **Claim 9** coupling the housing block (8) and / or the lead frame to the insulated metal substrate structure (3) such that a predetermined pressure for sintering is applied by the coupling and acts on the plurality of terminals (4). The method according to claim 8, including. **Claim 10** The method according to any one of the preceding claims, wherein the at least one terminal (4) and / or the metal top layer (17) is provided including at least one of copper, copper alloy, aluminum, and aluminum alloy. **Claim 11** providing the at least one terminal (4) and / or the insulated metal substrate structure (3) comprises providing a coating layer on the bottom surface (42) of the at least one terminal (4) and / or on the upper surface (171) of the metal top layer (17), the bottom surface (42) and the upper surface (171) being configured to face each other during sintering, and the coating layer of the at least one terminal (4) and / or the metal top layer (17) comprising one or more layers having at least one of nickel, silver, and gold, the method according to any one of the preceding claims. **Claim 12** providing the insulated metal substrate structure (3) comprises providing a molding material, aligning the positions of the metal top layer (17) and the metal bottom layer (19) relative to each other with a predetermined distance therebetween, transferring the provided molding material between the aligned metal top layer (17) and metal bottom layer (19), thereby forming the insulating resin layer (18) by molding, the transferring comprising the method according to any one of the preceding claims. **Claim 13** a semiconductor power module (10), comprising an insulated metal substrate structure (3) having a metal top layer (17), a metal bottom layer (19), and an insulating resin layer (18) sandwiched and bonded between both the metal top layer (17) and the metal bottom layer (19), at least one terminal (4), a sintered layer (5) disposed between the metal top layer (17) and the at least one terminal (4) by printing on the upper surface (171) of the metal top layer (17), such that, as a result, the sintered layer (5) connects the bottom surface (42) of the at least one terminal (4) to the upper surface (171) of the metal top layer (17) by sintering, the sintered layer (5) comprising predetermined sintered particles of micrometer size, the sintered layer (5) comprising the semiconductor power module (10). **Claim 14** a semiconductor power module (10), comprising an insulated metal substrate structure (3) having a metal top layer (17), a metal bottom layer (19), and an insulating resin layer (18) sandwiched and bonded between both the metal top layer (17) and the metal bottom layer (19), a plurality of terminals (4) coupled to a housing block (8) and / or a lead frame Each sintered layer (5) disposed between the metal top layer (17) and the terminal (4) and connecting the respective bottom surfaces (42) of the terminals (4) to the upper surface (171) of the metal top layer (17) by sintering, wherein the terminal (4) is sintered with a predetermined pressure acting on the plurality of terminals (4) applied by the bonding to be bonded to the insulating metal substrate structure (3), each sintered layer (5) and A semiconductor power module (10) comprising.

15. The semiconductor power module (10) according to claim 13 or 14, wherein the at least one terminal (4) comprises a given stress relaxation structure (7) having at least one of a spring structure, a thin portion, and a recess.

16. The semiconductor power module (10) according to any one of claims 13 to 15, comprising a plurality of terminals (4) coupled on one hand to a housing block (8) and / or a lead frame and on the other hand respectively connected to the upper surface (171) of the metal top layer (17) by sintering.

17. The semiconductor power module (10) according to claim 16, wherein the housing block (8) is formed as a resin body and the plurality of terminals (4) are partially embedded in the resin body.

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