Method of attaching terminal to metal base structure of semiconductor power module and semiconductor power module

Abstract

A method for attaching a terminal (4) to an insulating metal base structure (3) for a semiconductor power module (10) comprises providing at least one terminal (4) and providing a metal base structure (3) having a metal top layer (17), a metal bottom layer (19) and an insulating resin layer (18) arranged between the metal top layer (17) and the metal bottom layer (19). The method further comprises providing a sintered layer (5) and coupling it to the metal top layer (17) and / or the at least one terminal (4) to form a sintered region for the at least one terminal (4). The method further comprises coupling the at least one terminal (4) to the metal top layer (17) by means of sintering using a sintering tool (6) such that the sintered layer (5) is arranged between the metal top layer (17) and the at least one terminal (4) and connects the at least one terminal (4) to the metal top layer (17).

Description

Technical Field

[0001] The present disclosure relates to a method of attaching a terminal to an insulated metal base structure of a semiconductor power module. The present disclosure also relates to a semiconductor power module. Background Art

[0002] Conventional insulated metal bases used in low-power and mid-power semiconductor packaging technologies have both low insulation requirements and low thermal resistance requirements. Terminals are attached to the insulated metal bases, and it is necessary to reliably and cost-effectively connect the terminals to the insulated metal bases. Summary of the invention

[0003] Embodiments of the present disclosure relate to a method for attaching a terminal to a metal base structure, which helps save the cost of a semiconductor power module and achieves reliable functions even in high-voltage power module applications with high reliability requirements. Other embodiments of the present disclosure relate to corresponding semiconductor power modules.

[0004] According to one embodiment, a method for attaching a terminal to an insulated metal base structure for a semiconductor power module includes providing at least one terminal, and providing an insulated metal base structure having a metal top layer, a metal bottom layer, and an insulating resin layer arranged between the metal top layer and the metal bottom layer. The method also includes providing a sintering layer and coupling it to the top surface of the metal top layer and / or the bottom surface of at least one terminal to form a sintering area for at least one terminal. The method also includes coupling at least one terminal to the metal top layer using sintering by a sintering tool, so that the sintering layer is arranged between the metal top layer and at least one terminal and connects the at least one terminal to the metal top layer.

[0005] Due to the method, a sintered bond connection can be achieved on an insulating metal base, which can help the semiconductor power module to operate stably and reliably, even for high-voltage power module applications. For example, the method also helps to firmly attach the terminal to the insulating metal base by sintering while reducing the risk of damage to the insulating resin layer. The insulating metal base structure realizes a cost-effective technology for power semiconductor modules with low insulation and low thermal resistance requirements, and enables large-sized power modules to be used for applications in the low-voltage, medium-voltage and high-voltage ranges. The method can also help to achieve a sintered bond connection on a metal base structure, so that a semiconductor power module with such a metal base can operate stably and reliably.

[0006] It was found in the context of the present disclosure that alternative joining techniques, such as welding techniques, are capable of providing a reliable joining connection, but are considered to be crucial in view of carrying out a stable process on a base with an insulating resin sheet without damaging the base structure. In particular, ultrasonic welding is accompanied by a strong influence of thermal and mechanical stresses on the base structure, which is due to the high friction and pressure between the terminal pins and the base. The resin sheet is significantly softer than ceramics here, but is also brittle due to the incorporation of inorganic fillers and is seriously endangered by deformation and crack formation. During ultrasonic welding, corresponding deformations of the underlying soft layer may occur, for example in the case of thick copper wires ultrasonically bonded to thin brazing copper plates. The soft solder layer below the copper wire undergoes strong deformations similar to the soft resin sheet of the insulating metal base when the terminal pins are soldered thereto.

[0007] Ultrasonic welding experiments performed on insulating metal bases confirmed these expectations, namely that severe damage is produced in the insulating resin sheet during welding, so that ultrasonic welding on the base of the insulating metal base seems to be 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 welded terminal feet due to the welding technology. Additionally, it can be considered that laser welding or other welding technologies are also serious for damage to the base and especially the resin sheet due to the strong thermal shock and the mechanical stress introduced. The resin sheet is seriously endangered by deformation and cracking. In addition, there is a risk of delamination of the metallization from the resin sheet layer. When ultrasonic welding or laser welding or other terminal foot welding technology is applied to the circuit metallization of the insulating metal base, corresponding failure modes may occur.

[0008] By using the method to manufacture a metal base structure with one or more sintered terminals, the above-mentioned adverse effects caused by sintering the terminals with the metal top layer can be offset. The sintering process can reduce the mechanical and thermal stresses acting on the lower layer of the metal base structure. The risk of cracks or damage in the resin layer and delamination of the metal top layer can be reduced, and a stable semiconductor power module can be achieved, which can operate reliably even in high-voltage power module applications such as voltages ranging from 0.5 kV to as high as 10.0 kV.

[0009] According to one embodiment of the method, the step of providing and coupling the sintered layer comprises providing a substance having predetermined sintered particles and applying the substance to the top surface of the metal top layer (e.g., by printing), thereby forming a sintered area having a preformed sintered layer. The substance refers to a sintered raw material, for example in the form of a film or paste, which can be printed on a predetermined position on the metal top layer. The sintered material and therefore the sintered layer can be arranged in a predetermined manner as a pumpable liquid or viscous paste, including at least one of silver, copper, gold and nickel or other applicable metals as the main material. Alternatively or additionally, the sintered raw material can be arranged as a solid sheet or preform attached to the base and / or the terminal. Alternatively or additionally, the sintered material can be another material that can be applied by sintering. The sintered raw material can be pre-applied to a given position on the insulating metal base structure to ensure a prepared structure.

[0010] The sintered material may include microparticles and / or nanoparticles of the main component, which are capable of forming a strong bond connection or material bond connection between one or more terminals and the metal top layer. The sintered layer or the sintered material forming the sintered layer may include a material composition with a polymer and / or a solvent, a binder or a reagent in the raw material, which is removed during the sintering process. Considering the sintered connection between one or more terminals and the insulating metal base structure, the sintered layer realizes a more porous or less porous paste (which has a more porous or less porous shape) of a typically pure metal, which is different from the material of the terminal and the metal top layer (which can be realized by bulk copper or aluminum).

[0011] Sintering is the process of compacting and forming a solid block of material by heat and / or pressure without melting the joint mating parts to the point of liquefaction. Sintering tools can be used to apply pressure and / or heat to the terminal to bake the terminal and the top metal layer and the sintering layer between them together. Therefore, sintering can be described as baking the particles together, while the bonding is accomplished by a diffusion process between the particles.

[0012] According to another embodiment of the method, the sintering is carried out at a high pressure of up to 20 MPa applied to at least one terminal. For example, the high pressure is set in the range of 5 MPa to 25 MPa. For example, the sintering of the terminal and the metal top layer can be carried out at a high pressure of up to 10 MPa or 15 MPa. Generally, the relatively high pressure acting on the joint fitting is such that the quality of the sintered joint is reliable, which also depends on the porosity of the sintered material. In this case, the sintered layer has a low porosity and / or a high density. Therefore, the pressure used for sintering is given in coordination with the joint fitting and the selected sintering material.

[0013] According to another embodiment of the method, sintering is carried out at a low pressure of up to 2 MPa applied to at least one terminal. For example, the sintering of the terminal and the metal top layer can be carried out at a low pressure of 0.2 MPa, 0.5 MPa, 1 MPa or 1.5 MPa. The choice of sintering pressure also depends on the sensitivity of the joint fitting to pressure. In this case, the resin sheet of the base is particularly sensitive. For example, one or more terminals are part of 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. If low pressure is used for sintering, rubber or a positioning tool (which can also be part of the sintering tool) can be used to fix or hold the terminal in place. In addition, the sintering of the terminal and the metal top layer can be carried out without pressure, so that no additional pressure is used or very low pressure is used during sintering.

[0014] According to another embodiment of the method, the step of providing at least one terminal comprises providing at least one terminal with a given stress relief structure. The stress relief structure may comprise at least one of a spring structure, a thinned portion and a groove implemented on one or more terminals to beneficially influence the sintering process.

[0015] According to another embodiment of the method, the step of providing at least one terminal comprises providing a group or more terminals coupled to a housing block and / or a lead frame. The terminals may be coupled or directly connected to the lead frame or the housing block. The method may further comprise coupling the housing block and / or the lead frame with the terminals to the metal base structure such that a predetermined pressure for sintering is acting on the plurality of terminals applied by the coupling. Thus, the sintering pressure may be applied by the coupled housing block itself. Nevertheless, the pressure may still be exposed to the terminal pins of the respective terminals to facilitate a reliable sintering process.

[0016] One or more terminals may be made of or include at least one of copper, copper alloys, aluminum and aluminum alloys, or any other suitable metal or other conductive material. The metal top layer may also be made of or include at least one of copper, copper alloys, aluminum and aluminum alloys, or any other suitable metal or other conductive material.

[0017] According to another embodiment of the method, the metal top layer is provided with a coating on the top surface, which is configured to face the sintered material or the bottom surface of at least one terminal during sintering. Alternatively or additionally, at least one terminal is provided with a coating on the bottom surface, which is configured to face the sintered layer or the metal top layer of the metal base structure during sintering. Such a coating can be used to promote a bonding connection between the terminal, the sintered material film and / or the base metallization achieved by the metal top layer.

[0018] One or more of the above-mentioned coatings of the terminal and the metal top layer can be made of or include a noble metal (e.g., nickel and / or silver and / or gold) and / or one or more other metals. Such coatings can help prevent oxidation and / or improve the conditions of the sintering process and / or can also protect the resin layer of the metal base structure. The corresponding coating can partially or completely cover a predetermined surface of the bottom surface of the terminal or a predetermined surface of the top surface of the metal top layer. In addition, the corresponding coating can include one or more layers.

[0019] The insulating resin layer forms the dielectric layer and can be implemented as a prepreg sheet, which is assembled between two metal plates at the top and bottom, and the two metal plates form the metal top layer and the metal bottom layer. For example, such a metallized sheet or plate is bonded to the dielectric resin layer by a lamination process. The metallization structure required for the metal top layer can then be completed by subsequent masking and etching process steps to locally remove the conductive metal to form the final metallization structure. Alternatively, the top metallization structure can be formed by cutting or stamping, for example before the finished metal base structure is formed.

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

[0021] The metal top layer and the metal bottom layer are aligned relative to each other with a predetermined distance between them, which will substantially predetermine the subsequent thickness of the molded dielectric layer. For example, the thickness is defined along the stacking direction of the metal base structure, which direction can be presented as the z-direction. However, alignment can also be performed in the orthogonal x-direction and y-direction for suitable positioning, such as the suitable positioning of the metal pattern relative to the x-direction and the y-direction. For example, alignment can be achieved by placing the metal top layer on a release film or liner or other fixture (for example, in a mold groove of a molding tool). This enables accurate positioning of the metallization structure provided by the metal top layer relative to the metal bottom layer, and can be helpful if the metal top layer includes a separate metal liner, for example due to different operating potentials. In the case of lamination, the thickness of the resin layer is determined by the thickness and behavior of the laminate layer.

[0022] The thickness of the insulating resin layer can be a value of 50μm to up to 300μm. The thickness of the metal top layer can be a value of 0.15mm to up to 0.5mm or 0.15mm to 2.00mm. The terminal may include an L-shape, wherein the long terminal body extends mainly in the stacking direction and the terminal foot extends mainly in a lateral direction substantially perpendicular to the stacking direction. The terminal foot may form a plate with a thickness of 0.5mm to up to 1.5mm relative to the stacking direction. The thickness of the terminal foot and / or the sintered area formed by the sintering process may be, for example, smaller than other parts of the terminal. For example, the lateral dimension or area of ​​the terminal foot may be larger or smaller than the corresponding extension of the sintered layer. One or more terminals may implement a main terminal for power connection of a semiconductor power module or an auxiliary terminal for electrical signal connection or signal wiring.

[0023] At least one terminal may also include a structure that is provided to improve sintering. For example, such a sintering structure may be achieved by a roughened area or a thinned area, one or more grooves, recesses and / or notches in the terminal foot of the terminal. Such a sintering structure may be prepared on the top side and / or bottom side of the corresponding terminal and / or on the top surface of the metal top layer. Specific terminal structures may beneficially affect the sintering process and may help to form a material bonded or firmly bonded sintered joint.

[0024] By joining the terminal to the insulating metal base using the manufacturing or attachment method, adverse effects can be offset. For example, the risk of cracks, deformation or other damage can be reduced, especially in the insulating resin layer of the metal base structure, and a stable semiconductor power module can be achieved at a low cost, so that the semiconductor power module can operate reliably and have enhanced durability or service life.

[0025] Finally, it is pointed out that all the features and methods presented can be used individually or in combinations of two or more.

[0026] According to one embodiment, a semiconductor power module includes a base having a metal top layer, a metal bottom layer, and an insulating resin layer, the insulating resin layer being coupled to both the metal top layer and the metal bottom layer and being arranged between these layers. The semiconductor power module also includes at least one terminal and a sintering layer. The sintering layer is arranged between the metal top layer and the at least one terminal relative to the stacking direction of the semiconductor power module. The sintering layer connects the bottom surface of the at least one terminal to the top surface of the metal top layer by sintering.

[0027] Since the semiconductor power module can be manufactured by the embodiments of the above method, the features and characteristics of the method are also disclosed for the semiconductor power module, and vice versa. Therefore, the present disclosure includes multiple aspects, wherein all features described for one aspect are also disclosed for other aspects, even if the corresponding features are not explicitly mentioned in the context of a specific aspect.

[0028] According to an embodiment of the semiconductor power module, at least one terminal includes a given stress relief structure, which stress relief structure has, for example, at least one spring structure, a thinned portion and a groove. Therefore, each terminal may have a spring segment or an elastic portion to achieve a buffer structure or a stress relief structure, which helps to protect the resin layer from mechanical and / or thermal shock.

[0029] According to another embodiment, the semiconductor power module includes a plurality of terminals, which are coupled to the housing block and / or the lead frame on the one hand and are respectively connected to the top surface of the metal top layer by sintering on the other hand. The housing block can be formed as a resin body, and the plurality of terminals can be partially embedded in the resin body.

[0030] The semiconductor power module may further include a heat sink coupled to the metal bottom layer of the metal base structure to dissipate heat during operation of the semiconductor power module. The metal bottom layer forms the bottom of the metal base structure, and the metal bottom layer may be made of or include copper, aluminum and / or its corresponding alloys. Therefore, the semiconductor power module may include a separate heat sink. The additional heat sink may also be made of copper, aluminum and / or its corresponding alloys, or of a composite material such as aluminum-silicon carbide or magnesium-silicon carbide. Alternatively or additionally, the metal bottom layer of the metal base structure itself may be used as a heat sink, for example, on the bottom side relative to the stacking direction may be configured to include ribs, fins or protrusions to provide beneficial heat dissipation. The metal bottom layer may also be used as a substrate for the semiconductor power module.

[0031] The semiconductor power module including the metal base structure can also be partially or completely encapsulated by a dielectric gel or a resin prepared by molding or potting. In addition, the semiconductor power module can include two or more embodiments of the above-mentioned buffer structure. The semiconductor power module can also include electronic devices, such as chips, integrated circuits, sensors and / or other discrete devices.

[0032] Compared with welding technology, the proposed process of sintering the terminal feet onto the surface of the insulating metal base structure has great potential, for example, it can reduce the mechanical and thermal impact of the bonding process on the resin insulating sheet. The sintering process does not damage the resin layer that is sensitive to heat and pressure, making it interesting to use this rather cost-effective base technology. This attachment or manufacturing method for insulating metal base structures may be interesting for large power modules with enhanced reliability requirements and power modules for higher voltage levels. However, the method allows the manufacture of metal base structures and semiconductor power modules that can be applied to various products, such as low-voltage industrial and automotive products operating in the voltage range of 1.7 kV or below, but can also be used for products of higher voltage levels. When the standard installation of brazing a ceramic base to a substrate is replaced by an insulating metal base, the cost can be significantly reduced. On the one hand, the material cost can be reduced, and on the other hand, several other process steps (such as the bonding process between the base and the substrate in the power module assembly) are not required and can therefore be removed from the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Exemplary embodiments will be explained below with the aid of schematic drawings and reference numerals. The drawings show:

[0034] Figures 1 to 3 An embodiment of a method for attaching a terminal to a metal base structure of a semiconductor power module is shown in corresponding side views; and

[0035] Figure 4 A flow chart of a method for attaching one embodiment of a terminal to a metal base structure is shown.

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

[0037] Figure 1 A side view of an embodiment of a method step for attaching a terminal foot or terminal 4 to an insulating metal base structure 3 of a semiconductor power module 10 for a semiconductor device is shown. The semiconductor power module 10 comprises an insulating metal base structure 3 having a metal top layer 17, a metal bottom layer 19 and an insulating resin layer 18, which is arranged between the metal top layer 17 and the metal bottom layer 19 with respect to the stacking direction A.

[0038] The semiconductor power module 10 also includes a cooler or heat sink 1 having a fin structure or a rib structure, which is coupled to a metal base structure 3 via a bonding layer 2 and / or a thermal interface material layer. With respect to the stacking direction A shown, one or more terminals 4 are to be coupled to the metal top layer 17, and the heat sink 1 is coupled to the metal bottom layer 19 at the bottom via the bonding layer 2.

[0039] In this regard, terms such as "above", "below", "top", "upper" and "bottom" refer to positions or directions shown in the drawings relative to the stacking direction A. Thus, the height or thickness of the element is related to the stacking direction A, while the lateral direction B is perpendicular to the stacking direction A (see FIG. Figures 1 to 3 ).

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

[0041] Alternatively or additionally, the metal base structure 3 includes a resin layer 18 formed by molding, for example, by injection, transfer molding or compression molding. The resin of the resin layer can contain inorganic fillers, ceramic materials, such as AlN, Si3N4, BN, Al2O3 or SiO2. The metal bottom layer 19 can be made of copper and / or aluminum and / or its corresponding alloy, or include copper and / or aluminum and / or its corresponding alloy. The circuit metallization formed by the metal top layer 17 can be made of copper and / or aluminum and / or its corresponding alloy, or include copper and / or aluminum and / or its corresponding alloy. In addition, the metal top layer 17 can be partially or completely coated, and the corresponding coating of the circuit metallization can be made of or include a noble metal (such as nickel and / or gold and / or silver and / or other metals), such as nickel and / or gold and / or silver and / or other metals.

[0042] The semiconductor power module 10 further includes a sintering layer 5, which may include silver or copper and is arranged between the metal top layer 17 and at least one terminal 4. The sintering layer 5 is used to connect the bottom surface 42 of the terminal 4 to the top surface 171 of the metal top layer 17 by sintering. The sintering layer 5 may have a thickness of 20 μm-50 μm or even up to 250 μm. In consideration of cost reduction, the sintering layer 5 may be formed thinner and may be pre-applied to one or both of the joint fittings.

[0043] Sintering can bond the main or auxiliary terminal 4 to the insulating metal base structure 3, but it can also be bonded to corresponding base structures based on alternative technologies, such as stamped and molded metal bases. Compared with welding technology (where strong thermal and / or mechanical shocks make the bonding process very difficult), when bonding the terminal foot to the circuit metallization or metal top layer 17 by sintering, only limited static mechanical pressure shocks and moderately increased temperatures need to be considered.

[0044] like Figures 1 to 3 As shown, one or more terminal legs can be joined to the top surface 171 of the insulating metal base structure 3 by a sintering process. For example, pressure and / or heat for the sintering process can be applied by a sintering tool 6 acting on the top surface 41 of the terminal 4. However, heat can also be applied to the entire insulating metal base structure 3 and the assembly device for manufacturing the semiconductor power module 10. The sintering tool 6 can also accurately position the terminal 4 or hold the terminal 4 in a specified position during the sintering process. The sintering connection is provided by a sintering material configured to form a sintering layer 5, which has micron or submicron sized particles of silver, copper or any other material suitable for the sintering process.

[0045] The sintering process can be used for individual terminals 4 or groups of multiple terminals. A simultaneous sintering process is also possible for multiple terminals arranged in a shared terminal or housing block or lead frame (see Figure 3 ). In order to further improve the counteracting of the mechanical stresses to which the joint connection is subjected and to contribute to the reliability, the terminal 4 may have a stress relief structure 7, for example intended to compensate for possible vibrations or mismatches in the coefficients of thermal expansion or to compensate for mechanical or geometric tolerances in the housing block or the terminal structure without increasing stress (see Figure 2 ).

[0046] The terminal 4 may be made of copper, aluminum and / or their corresponding alloys, or include copper, aluminum and / or their corresponding alloys, and the terminal 4 may implement a main terminal or an auxiliary terminal of the semiconductor power module 10. In addition, the terminal 4 may include a coating that partially or completely covers the top surface 41 and / or the bottom surface 42 of the terminal 4. Such a coating may beneficially affect the sintering process and / or may protect one or more surfaces of the terminal 4 from oxidation, and may be made of or include a noble metal (e.g., nickel, gold, silver and / or other metals). The coating may also include one or more layers of such materials.

[0047] The method steps for attaching the terminal 4 to the metal base structure 3 may be as follows: Figure 4 The process is performed as shown in the flowchart. In step S1, at least one terminal 4 is provided. The terminal 4 may be provided to include one or more coatings on its top surface 41 and / or bottom surface 42.

[0048] In step S2, the metal base structure 3 is provided with a metal top layer 17, a metal bottom layer 19 and an insulating resin layer 18 between the metal top layer 17 and the metal bottom layer 19. A coating may also be applied at least partially on the top surface 171 of the metal base structure 3.

[0049] In step S3, a sintering material may be provided to form the sintering layer 5. For example, the sintering material includes microparticles and / or nanoparticles, including silver and / or gold provided as a substance or raw material. The sintering material may then be applied to the top surface 171 of the metal top layer 17 and / or the bottom surface 42 of the terminal 4 by printing, thereby forming a sintering area where the sintering layer 5 is to be formed. The sintering material may also be a solid sheet or preform that is attached to one of the connector mating parts.

[0050] In another step S4, the terminal 4 is pressed against the metal top layer 17 with a specified pressure, and heating of the assembled terminal 4, the metal top layer 17 and the sintering material therebetween is started. To this end, the specified pressure and heat can be applied simultaneously, or the pressure can be applied before or after the heat is introduced into the device. For example, preheating can be performed before entering the sintering machine. This preheating process can introduce a temperature setting slightly lower than the temperature used during the sintering process.

[0051] Therefore, it can be said that the sintered material is baked and transformed into the sintered layer 5, and the sintered layer 5 connects the bottom surface 42 of the terminal 4 to the top surface 171 of the metal top layer 17 by sintering.

[0052] One or more terminals 4 can realize main terminals or auxiliary terminals and connect their respective terminal feet to the top surface 171 of the insulating metal base 3 by sintering. The sintered connection between the terminal feet and the top surface 171 is made of particles of silver, copper or other materials suitable for sintering processes. The sintered particles can have a diameter in the micron or submicron range. Depending on the type and material of the terminal, the terminal feet have a thickness of 0.5-1.5 mm. In order to improve the sintering process or protect the joint fittings, for example to prevent oxidation, the top surface 171 of the base and / or the top surface 41 of the terminal feet and / or the bottom surface 42 of the terminal feet can be coated with a metal layer, for example made of nickel, silver and / or gold.

[0053] There are several possible arrangements for mounting the terminals 4 to the top surface 171 of the metal base structure 3: First, one or more individual terminals 4 can be connected to the top surface 171 individually by sintering. Second, multiple terminals 4 can be arranged in a group, as in the case of a lead frame, where the terminal legs are simultaneously bonded to the base metallization, which is realized by the metal top layer 17. Finally, multiple terminals 4 arranged in a common terminal or housing block 8 can be sintered simultaneously (see Figure 3). Here, for example, at least a portion of several terminals 4 are embedded in a shared resin body of a housing block 8. The housing block 8 may form a portion of a module housing of a semiconductor power module 10, which is prepared by a molding process. A sequential sintering process is also possible for the terminals of the lead frame or housing block.

[0054] Additionally, one or more stress relief structures 7 may be implemented to one or more terminals 4 (see Figure 2 and Figure 3 ). Such a stress relief structure can help to compensate for thermal expansion or vibration or other forces or to compensate for mechanical or geometric tolerances in the housing or terminal structure without increasing the stress to which the joint connection is subjected. The stress relief structure 7 of each terminal 4 can be realized by different designs, such as one or more spring portions, thinned portions and / or openings / holes on the axis of the terminal.

[0055] Compared with conventional bonding techniques using ultrasonic welding processes, sintering can, for example, reduce mechanical and thermal shocks to the resin insulating layer 17. Additionally, for example, in order to form a very stable and reliable connection, one or more terminals 4 can be coupled to the metal top layer 17 by soldering, gluing, dry contact, welding and / or any other applicable bonding method for fixing to the circuit metallization portion implemented by the metal top layer 17. The terminals 4 can also be coupled to the metal top layer 17 by sintering before forming the metal base structure 3 to further prevent mechanical shocks to the insulating resin layer 18.

[0056] The sintering process itself can be implemented in a variety of options, depending on the joint partner and / or the sintering material, for example:

[0057] • Sintering can be performed under high pressure by using a pressure of about 20 MPa or using pressure values ​​from 5 MPa up to 25 MPa.

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

[0059] Pressureless sintering;

[0060] Heating may be carried out in the range of 200 to a maximum of 270°C, or a maximum of 290°C, or a maximum of 300°C.

[0061] Heating and maintaining heat can be achieved by an oven, a heating plate and / or a heated sintering tool for heating the sintering raw materials and the joint fittings from one or more sides. Pressure can be applied by a mechanical clamping element, which can also include a positioning and / or fixing structure formed in conjunction with the corresponding terminal design to be sintered. The sintering material can include micron and / or nano sintering particles, where larger particles and higher sintering pressures can be used, which also depends on the porosity requirements and the intended application of the semiconductor power module 10.

[0062] For example, the sintering raw material is provided as a paste-like substance having nano-sized silver particles and / or copper particles. Then, by applying a relatively low pressure (from 0.1 MPa to a maximum of 5.0 MPa) within a time range of 1-10 minutes or up to 20 minutes and applying heat having a temperature of 200° C.-300° C., a sintering layer 5 can be formed. Therefore, alternatively or optionally, the paste-like substance may include micron-sized silver particles and / or copper particles.

[0063] Alternatively, for example, the sintering raw material may be provided as a silver foil and / or a copper foil having micron-sized silver particles and / or copper particles. Then, by applying a relatively high pressure (from 5 MPa to a maximum of 25 MPa) and applying heat having a temperature of 200° C. to 300° C. within a time range of 1 minute to 10 minutes or at most 20 minutes, the sintering layer 5 may be formed. Silver particles, gold particles, nickel particles or copper particles may be selected, depending on the cost of the semiconductor power module 10, the sintering process and its temperature and pressure parameters and / or the design and intended application and / or the requirements for the sintered joint and porosity of the sintered layer 5.

[0064] The Figure 1 to Figure 2 The illustrated embodiments represent exemplary embodiments of improved metal base structures 3, semiconductor power modules 10, and methods of manufacturing the same; therefore, they do not constitute a complete list of all embodiments. Actual arrangements and methods may vary from the embodiments illustrated, for example, from the perspective of metal base structures 3 and semiconductor power modules 10.

[0065] Reference numerals

[0066] 1 Heat sink

[0067] 2 Bonding layer

[0068] 3 Metal base structure

[0069] 4 terminals

[0070] 41 The top surface of the terminal

[0071] 42 Terminal bottom surface

[0072] 5 Sintering layer

[0073] 6 Sintering tools

[0074] 7 Stress relief structure

[0075] 8 Housing block

[0076] 10Semiconductor power module

[0077] 17 Metal Top Layer

[0078] 171 Top surface of metal top layer

[0079] 18 resin layer

[0080] 19 Metal base

[0081] AStacking direction

[0082] B horizontal direction

[0083] S(i) Steps of a method for attaching a terminal to a metal base structure

Claims

1. A method for attaching a terminal (4) to an insulated metal base structure (3) for a semiconductor power module (10), comprising: - providing at least one terminal (4), - providing the insulating metal base structure (3), the insulating metal base structure having a metal top layer (17), a metal bottom layer (19) and an insulating resin layer (18) arranged between the metal top layer (17) and the metal bottom layer (19), - providing a sintering layer (5) and coupling the sintering layer to the top surface (171) of the metal top layer (17) and / or the bottom surface (42) of the at least one terminal (4) to form a sintering region of the at least one terminal (4), and - coupling the at least one terminal (4) to the metal top layer (17) by sintering, so that the sintering layer (5) is arranged between the metal top layer (17) and the at least one terminal (4) and connects the at least one terminal (4) to the metal top layer (17), wherein the steps of providing the sintering layer (5) and coupling the sintering layer include: - providing a substance or sintering raw material having predetermined sintering particles of micrometer size, and - applying the substance or sintering raw material onto the top surface (171) of the metal top layer (17) by printing and thus forming the sintering area and preforming the sintering layer (5).

2. A method for attaching a terminal (4) to an insulated metal base structure (3) for a semiconductor power module (10), comprising: - providing a plurality of terminals (4) coupled to the housing block (8) and / or the lead frame, - providing the insulating metal base structure (3), the insulating metal base structure (3) having a metal top layer (17), a metal bottom layer (19) and an insulating resin layer (18) arranged between the metal top layer (17) and the metal bottom layer (19), - providing a sintering layer (5) and coupling the sintering layer to the top surface (171) of the metal top layer (17) and / or the bottom surface (42) of each of the terminals (4) to form a sintering area of ​​each of the terminals (4), and - coupling the terminals (4) to the metal top layer (17) by sintering, so that the corresponding sintering layer (5) is arranged between the metal top layer (17) and the associated terminals (4), and connecting the terminals (4) to the metal top layer (17), wherein the coupling of the terminals (4) includes coupling the housing block (8) and / or the lead frame to the insulating metal base structure (3), so that a predetermined pressure for sintering acts on the multiple terminals (4) applied by the coupling.

3. The method according to any one of the preceding claims, wherein the steps of providing the sintered layer (5) and coupling the sintered layer comprise: - providing a substance having predetermined sintering particles or a sintering raw material, and - applying the substance or sintering raw material onto the top surface (171) of the metal top layer (17) by printing and thus forming the sintering area and preforming the sintering layer (5).

4. The method according to any one of the preceding claims, wherein the sintered layer (5) comprises at least one of silver, copper, gold and nickel.

5. Method according to any of the preceding claims, wherein sintering is performed at a high pressure of up to 25 MPa acting on the at least one terminal (4).

6. The method according to any one of claims 1 to 4, wherein sintering is performed on the at least one terminal (4) without pressure or under low pressure up to 2 MPa.

7. The method according to any one of the preceding claims, wherein the step of providing the at least one terminal (4) comprises: The at least one terminal (4) is provided with a given stress relief structure (7), wherein the stress relief structure (7) comprises at least one of a spring structure, a thinned portion and a groove.

8. The method according to any one of the preceding claims, wherein the step of providing the at least one terminal (4) comprises: A plurality of terminals (4) are provided that are coupled to the housing block (8) and / or the lead frame.

9. The method according to claim 8, comprising: The housing block (8) and / or the lead frame are coupled to the insulating metal base structure (3) so that a predetermined pressure for sintering acts on the plurality of terminals (4) applied by the coupling.

10. The method according to any of the preceding claims, wherein the at least one terminal (4) and / or the metal top layer (17) is provided comprising at least one of copper, a copper alloy, aluminum and an aluminum alloy.

11. The method according to any one of the preceding claims, wherein the step of providing the at least one terminal (4) and / or the insulating metal base structure (3) comprises: A coating is provided on the bottom surface (42) of the at least one terminal (4) and / or on the top surface (171) of the metal top layer (17), wherein the bottom surface (42) and the top surface (171) are configured to face each other during sintering, and wherein the coating of the at least one terminal (4) and / or the metal top layer (17) includes one or more layers, the one or more layers having at least one of nickel, silver and gold.

12. The method according to any one of the preceding claims, wherein the step of providing the insulating metal base structure (3) comprises: - providing a molding mass, - aligning the metal top layer (17) and the metal bottom layer (19) relative to each other with a predetermined distance between the metal top layer (17) and the metal bottom layer (19), and - introducing the provided molding substance between the aligned metal top layer (17) and the metal bottom layer (19), and thereby forming the insulating resin layer (18) by molding.

13. A semiconductor power module (10), comprising: - an insulating metal base structure (3), the insulating metal base structure having a metal top layer (17), a metal bottom layer (19), and an insulating resin layer (18), the insulating resin layer being coupled between the metal top layer (17) and the metal bottom layer (19), - at least one terminal (4), and - a sintering layer (5), the sintering layer (5) being arranged between the metal top layer (17) and the at least one terminal (14), and being arranged on the top surface (171) of the metal top layer (17) by printing, so that the sintering layer (5) connects the bottom surface (42) of the at least one terminal (4) to the top surface (171) of the metal top layer (17) by sintering, wherein the sintering layer (5) comprises predetermined sintering particles of micrometer size.

14. A semiconductor power module (10), comprising: - an insulating metal base structure (3), the insulating metal base structure having a metal top layer (17), a metal bottom layer (19), and an insulating resin layer (18), the insulating resin layer being coupled between the metal top layer (17) and the metal bottom layer (19), - a plurality of terminals (4) coupled to the housing block (8) and / or the lead frame, and - A corresponding sintered layer (5) is arranged between the metal top layer (17) and the terminals (4), and the corresponding sintered layer connects the bottom surfaces (42) of the respective terminals (4) to the top surfaces (171) of the metal top layer (17) by sintering, wherein the terminals (4) are coupled to the insulating metal base structure (3) by sintering, and wherein a predetermined pressure acts on the multiple terminals (4) applied by the coupling.

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

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

17. The semiconductor power module (10) according to claim 16, wherein the case 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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