Method for attaching terminals to a metal substrate structure for semiconductor power modules and semiconductor power modules

Abstract

A method for attaching a terminal (4) to a metal substrate structure (3) for a semiconductor power module (10) includes providing at least one terminal (4) and providing the metal substrate structure (3) with 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). The method further includes providing and bonding a buffer structural element (7) to an upper surface (171) of the top metal layer (17) to form a protrusion for the at least one terminal (4). The method further includes bonding the at least one terminal (4) to the buffer structural element (7) by ultrasonic welding such that the buffer structural element (7) is disposed between the top metal layer (17) and the at least one terminal (4) and is materially bonded to the at least one terminal (4).

Description

【Technical Field】 【0001】 The present disclosure relates to a method for attaching terminals to a metal substrate structure of a semiconductor power module with an insulating resin sheet. The present disclosure further relates to a semiconductor power module for a semiconductor device. 【Background Art】 【0002】 Conventional insulated metal substrates form technologies 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 secure connection of the terminals on the insulated metal substrate is required. German Patent No. 102012211952 B4 discloses a power semiconductor module having a substrate disposed on a cooling device or base plate. The power semiconductor components are conductively connected to strip conductors. Adjusting elements and connectors are disposed on the strip conductors. The main surface of the adjusting element is fixed adjacent to the connector such that two connection types are formed, and the other main surface of the adjusting element is conductively and firmly bonded by a connection unit. European Patent Application Publication No. 0706221 A2 discloses a further semiconductor arrangement having contact elements. 【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 metal substrate structure for a semiconductor power module that can function reliably even in high-voltage power module applications. Further embodiments of the present disclosure relate to corresponding semiconductor power modules. 【0004】 According to one embodiment, a method for attaching terminals to a metal substrate structure for a semiconductor power module includes providing at least one terminal and providing the metal substrate structure with 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 buffer structural element to form a projection for at least one terminal and bonding it to the top surface of the top metal layer. The method further includes bonding at least one terminal to the buffer structural element by ultrasonic welding using an ultrasonic welding head acting with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the terminal, the buffer structural element, and / or the metal substrate structure, such that the buffer structural element is disposed between the top metal layer and the at least one terminal and materially bonded to the at least one terminal by a weld joint. 【0005】 The described method enables ultrasonic welding joint connections on insulating metal substrates, contributing to the stable and reliable function of semiconductor power modules, even in high-voltage power module applications. For example, the method contributes to the secure and cost-effective attachment of terminals to insulating metal substrates by ultrasonic welding while reducing the risk of damage to the insulating resin layer. 【0006】 Considering alternative connection processes, ultrasonic welding offers reliability of the ultrasonic weld interface against thermal load cycles, improved heat conduction from the interface, ease of manufacturability, and throughput. Due to buffer structural elements, ultrasonic welding can also be used as an established technique for insulating metal substrate structures. Currently, housings or terminals need to be redesigned. 【0007】 The insulating metal substrate structure enables a cost-effective technology for power semiconductor modules with low insulation and low thermal resistance requirements. 【0008】 The buffer structure is a deliberately formed protrusion that allows for protection of the resin layer against mechanical shocks introduced by ultrasonic welding and enables locally greater thickness or reinforcement of the circuit metallization of the top layer of metal at the terminal location. Furthermore, the buffer structure provides protection of the resin layer against thermal shocks. The protrusion provides longer mechanical and thermal paths between the welding location and the resin layer, as well as mechanical reinforcement of the substrate. 【0009】 The thicker or wider the buffer structural element, the smaller the mechanical stress introduced into the insulating metal substrate structure. In this respect, the height or thickness of the buffer structural element can have a greater impact on stress absorption or buffering than the width or length of the buffer structural element. Furthermore, to contribute to stress buffering or absorption, the buffer structural element may include, for example, a gold coating that allows for the reduction of frictional forces. However, such a coating also contributes to the reliable and stable mounting of the buffer structural element, such as sintering. 【0010】 The ultrasonic welding process is performed in conjunction with terminals, buffer structural elements, and metal substrate structures. For example, ultrasonic welding is performed at an ultrasonic frequency of 20 kHz. 【0011】 In connection with this disclosure, it is recognized that conventional insulating metal substrates enable technology for low and medium-power semiconductor packages that simultaneously have low insulation and low heat resistance requirements. When reliability requirements are low, terminals can be soldered or bonded to the substrate. Welding usually provides better reliability, but the welding process can be critical to the substrate structure. Considering conventional configurations of such insulating metal substrates, the corresponding terminals are connected to the upper metallization using welding techniques to provide a joint connection that can be critical with respect to the stable process on the substrate and the resin isolation sheet beneath the metallization. The welding process can lead to damage to the substrate structure, and ultrasonic welding, for example, has a strong influence on the substrate structure due to friction and pressure between the terminal base and the substrate, resulting in thermal and mechanical stress. Here, the resin sheet is highly vulnerable to deformation and crack formation. There is also a risk that the metallization will delaminate from the resin sheet layer. When ultrasonic welding of the terminal base is applied to the circuit metallization of an insulating metal substrate, corresponding failure modes may occur. 【0012】 By using the described method for manufacturing a metal substrate structure to which one or more terminals are attached, the aforementioned adverse effects can be negated by buffer structural elements specifically introduced between the terminals and the metal top layer. The protrusions on the upper surface of the metal top layer formed by the buffer structural elements attenuate or reduce the mechanical and thermal stresses caused by ultrasonic welding, taking into account the underlying layers of the metal substrate structure. The buffer structural elements can be formed by separate metal elements on the metal top layer and / or integrally formed with the metal top layer. Furthermore, the risk of crack and damage formation in the resin layer and delamination of the metal top layer can be reduced, enabling stable semiconductor power modules that function reliably, even in high-voltage power module applications from 0.5kV to 10.0kV, for example. 【0013】 According to one embodiment of the method, providing and joining buffer structural elements includes providing metal block elements separate from the top metal layer and joining the metal block elements to the upper surface of the top metal layer by a bonding layer. Alternatively or additionally, providing and joining buffer structural elements may include providing metal block protrusions formed integrally with the top metal layer and projecting from the upper surface of the top metal layer. 【0014】 According to a further embodiment of the method, buffer structural elements are provided to form protrusions intentionally positioned by metal blocks or spring or elastic elements having heights ranging from 0.3 mm to 2.0 mm. The height is related to the dimension along the lamination direction of the metal substrate structure and at least one terminal, and can also be referred to as the thickness of the protrusions extending over adjacent upper surfaces of the top metal layer. 【0015】 The buffer structural elements may be made from or include at least one of copper, copper alloys, aluminum and aluminum alloys, or any other applicable metal or other conductive material. The metal top layer may also be made from or include at least one of copper, copper alloys, aluminum and aluminum alloys, or any other applicable metal or other conductive material. The buffer structural elements and the metal top layer may include different or the same materials having similar or identical coefficients of thermal expansion, for example, to provide similar or identical thermal expansion. 【0016】 According to a further embodiment of the method, the buffer structure element comprises a coating layer on its upper surface configured to face the lower surface of at least one terminal during ultrasonic welding, and / or a coating layer on its lower surface configured to face the upper surface of the top metal layer during ultrasonic welding. Alternatively or additionally, there may be a coating layer on the lower surface of the buffer structure configured to face the upper surface of the top metal layer, for the purpose of facilitating the bonding connection between the buffer element and the substrate metallization. 【0017】 Alternatively or additionally, at least one terminal comprises a first coating layer on its upper surface configured to face the ultrasonic welding head during ultrasonic welding, and / or a second coating layer on its lower surface configured to face the top metal layer of the metal substrate structure during ultrasonic welding. 【0018】 One or more of the aforementioned coating layers on the buffer structure elements and the first and second coating layers on the terminals may be made of or include precious metals such as nickel and / or silver and / or gold, and / or one or more other metals. Such coatings can contribute to preventing oxidation and / or improving the condition of the ultrasonic welding process. Each coating may partially or completely cover a given surface of the buffer structure or terminal. Furthermore, each coating may comprise one or more layers. 【0019】 The buffer structure can be bonded to the circuit metallization or metal top layer by at least one of soldering, bonding, sintering, and dry contact, or any other suitable bonding method. The circuit metallization or metal top layer may also have a corresponding coating. The buffer structure can be implemented as a metal block or spring or elastic element to form a predetermined protrusion. The implementation of the buffer structure on the top surface of the metal substrate structure is provided at the location where the terminals are joined by ultrasonic welding. Furthermore, there may be two or more buffer structures associated with two or more terminals. Each buffer structure contributes to the protection of the resin layer against mechanical and thermal shocks. 【0020】 For example, one or more terminals can be directly welded to their respective buffer structural elements, and the buffer structural elements can be directly attached to the top surface of the top metal layer to form their respective copper-to-copper direct contacts. Instead of direct contact, one or more coating layers can be placed between the opposing surfaces. Thus, the coating layer can be placed between the underside of each terminal and the upper or top surface of the associated buffer structural element. Alternatively or additionally, a coating layer can be placed between the underside of the buffer structural element and the top surface of the top metal layer. 【0021】 Buffer structural elements may include materials with a yield strength greater than that of one of the terminal or mating materials. Alternatively or additionally, buffer structural elements may include materials with a melting point higher than that of one of the terminal or mating materials. Such mating material specifications can contribute to a reliable and dependable ultrasonic welding process. 【0022】 The resin layer forms a dielectric layer and can be realized as a prepreg sheet assembled between two upper and lower metal plates forming the top and bottom metal layers. Such a metallization sheet or plate is bonded to the dielectric resin layer, for example, by a lamination process. The desired metallization structure for the top metal layer can then be created by subsequent steps of masking and etching processes to locally remove the conductive metal, thereby creating 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. 【0023】 Alternatively, the resin layer can be formed by molding. For such a molded dielectric layer, the molded material realizes a pumpable material having predetermined material properties. The pumpable material is the liquid or viscous raw material of the resin layer to be formed. For example, the molded 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, for example, based on a ceramic material, for improved thermal conductivity and / or CTE adjustment relative to the top metal layer and / or bottom metal layer. For example, the molded dielectric layer includes a resin-based dielectric material having a ceramic filler, such as Al2O3, AlN, BN, Si3N4, or SiO2. For example, the dielectric layer is epoxy containing a filler. The dielectric layer can also be based on transfer, injection or compression molding, or other materials suitable for other applicable molding techniques such as bismaleimide, cyanate esters, polyimide, and / or silicone. Alternatively or additionally, the dielectric layer may include a ceramic material and / or a hydroset material, or a combination of two or more of the aforementioned components. 【0024】 The thickness of the molded dielectric layer is substantially predetermined by aligning the top metal layer and the bottom metal layer relative to each other with a predetermined distance between them. For example, the thickness is defined along the lamination direction of the metal substrate structure, which may exhibit a z-direction. However, alignment can also be performed in the perpendicular x and y directions for proper positioning of the metal pattern in the x and y directions, for example. For example, alignment can be achieved by placing the top metal layer on a release film or liner, or by other fixing in the mold chase of a molding tool, for example. This allows for precise positioning of the provided metallization structure of the top metal layer relative to the bottom metal layer and may be useful, for example, when the top metal layer contains 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 layer. 【0025】 The thickness of the insulating resin layer can have a value ranging from 100 μm to 200 μm. The thickness of the top metal layer can have a value ranging from 0.15 mm to 2.00 mm. The height or thickness of the buffer structure element can have a value, for example, from 0.3 to 2.0 mm. The terminal can be provided with an L-shape having a terminal body mainly extending in the stacking direction and a terminal base mainly extending in a lateral direction substantially perpendicular to the stacking direction. The terminal base may 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 base and / or the welding region formed by an ultrasonic welding process may be smaller compared to other parts of the terminal, for example, to provide an ultrasonic welding process with reduced stress. One or more terminals can be made of, for example, copper or a copper alloy, or contain copper or a copper alloy, and can realize a main terminal or an auxiliary terminal for electrical signal connection of a semiconductor power module. 【0026】 At least one terminal or buffer element can also include a structure prepared for improved ultrasonic welding. Such a welding structure can be realized, for example, by one or more slots, grooves, and / or recesses in the terminal base of the terminal, or by a roughened or thinned region. Such a welding structure can be made on the upper side and / or the lower side of each terminal or buffer element. A specific terminal structure can beneficially affect the ultrasonic welding process and contribute to the formation of a welded joint that bonds materially. 【0027】 By using the described manufacturing or mounting method and buffer structure elements, it is possible to counteract adverse effects even in the use of an ultrasonic welding process. Therefore, it is possible to reduce the risk of formation of cracks or damage, particularly in the insulating resin sheet of a metal substrate structure, and a low-cost and stable semiconductor power module enabling a highly reliable function of the semiconductor power module can be realized. 【0028】 Finally, it is pointed out that all the proposed features and methods can be used alone, but combinations of two or more can also be used. 【0029】 According to one embodiment, a semiconductor power module includes a metal top layer, a metal bottom layer, and an insulating resin layer coupled to both the metal top layer and the metal bottom layer and disposed therebetween. The semiconductor power module further includes at least one terminal and a buffer structure element coupled to an upper surface of the metal top layer forming a protrusion for the at least one terminal. The at least one terminal is coupled to the buffer structure element by ultrasonic welding using an ultrasonic welding head such that the buffer structure element is materially bonded to the at least one terminal and disposed between the metal top layer and the at least one terminal. 【0030】 As a result of manufacturing the described semiconductor power module by an embodiment of the above method, the features and characteristics of the method are also disclosed with respect to the semiconductor power module, and vice versa. Thus, the present disclosure includes several aspects, and all features described with respect to one of the aspects are also disclosed herein with respect to other aspects, even if each feature is not explicitly recited in the context of a particular aspect. 【0031】 According to one embodiment of a semiconductor power module, the buffer structure element comprises a metal block element formed separately from the metal top layer and / or a metal block element formed integrally with the metal top layer, each projecting from the top surface of the metal top layer at a predetermined height in conjunction with an ultrasonic welding process performed. The buffer structure element can include heights of 0.3 mm or 0.5 mm to 2.0 mm in relation to the adjacent region of the top surface of the metal top layer, as well as the stacking direction of the metal substrate structure and at least one terminal. For example, the buffer structure element can include heights of up to 2.0 mm, such as 0.4 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm. The width and / or length of each buffer structure element and / or terminal corresponding to the transverse direction perpendicular to the stacking direction of the metal substrate structure can have values ​​of, for example, 2 mm to 4 mm each. 【0032】 A semiconductor power module may further comprise a heat sink coupled to the bottom metal layer of a metal substrate structure to dissipate heat during the operation of the semiconductor power module. The bottom metal layer forms the base of the metal substrate structure and may be made of or contain copper, aluminum, and / or corresponding alloys. Thus, the semiconductor power module may comprise a separate heat sink. Alternatively or additionally, the bottom metal layer of the metal substrate structure can act as the heat sink itself and may be configured, for example, to have ribs, fins, or protrusions on the bottom side with respect to the stacking direction to provide beneficial heat dissipation. The bottom metal layer may further function as the base plate of the semiconductor power module. 【0033】 A semiconductor power module including a metal substrate structure can be further partially or completely encapsulated by a resin or dielectric gel fabricated by molding or potting. Terminals may function as power terminals or as auxiliary terminals used, for example, for signal wiring. Furthermore, the semiconductor power module may include two or more embodiments of the buffer structure described above. The semiconductor power module may further include electronic devices, such as chips, integrated circuits, sensors and / or other individual devices. 【0034】 The proposed process of ultrasonic welding terminal bases on buffer structures mounted on an insulating metal substrate has strong potential to significantly reduce mechanical and thermal effects on the resin insulating sheet. A successful ultrasonic welding process is possible without damaging the heat and pressure-sensitive resin layer, making the use of this relatively cost-effective substrate technology interesting. Such a method of mounting or manufacturing metal substrate structures could be interesting for large power modules and power modules for higher voltage classes with enhanced reliability requirements. However, the described method also enables the manufacture of metal substrate structures and semiconductor power modules applicable to a wide variety of products, such as low-voltage industrial and automotive products operating in voltage ranges of 0.5kV or less. Significant cost savings may be possible when replacing the standard configuration of ceramic substrates soldered to a base plate with insulating metal substrates, despite the additional process step of joining metal blocks at terminal base locations or preparing localized areas of upper substrate metallization with enhanced thickness. On the one hand, material costs can be reduced, and on the other hand, several other process steps, such as the bonding process between the substrate and the base plate in power module assemblies, are not required. 【0035】 Exemplary embodiments are described below with reference to schematic diagrams and reference numbers. [Brief explanation of the drawing] 【0036】 [Figure 1] This is a side view of one embodiment of a method for attaching terminals to a metal substrate structure of a semiconductor power module. [Figure 2] This is a side view of a further embodiment of a method for attaching terminals to a metal substrate structure of a semiconductor power module. [Figure 3] This is a flowchart illustrating a method for attaching one embodiment of a terminal to a metal substrate structure. [Modes for carrying out the invention] 【0037】 The attached drawings are included to provide further understanding. Please understand that the embodiments shown in the drawings are illustrative and not necessarily drawn to a specific scale. The same reference numerals indicate elements or components having the same function. The descriptions of elements or components in each of the following drawings will not be repeated insofar as they correspond to each other in terms of their function in different drawings. For clarity, elements may not be represented by the same reference numeral in all drawings in some cases. 【0038】 Figure 1 shows a side view of one embodiment of a method step for attaching a terminal base or terminal 4 to a metal substrate structure 3 of a semiconductor power module 10 for a semiconductor device. The semiconductor power module 10 comprises a 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 with respect to the stacking direction A. 【0039】 The semiconductor power module 10 further comprises a cooler or heat sink 1 having a rib structure bonded to a 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, the terminals 4 should be bonded to the top metal layer 17 and, below the heat sink 1, to the bottom metal layer 19 via the bonding layer 2. 【0040】 In this regard, terms such as "above," "under," "top," "upper," and "bottom" refer to the orientation or direction shown in the diagram and indicated with respect to the stacking direction A. Therefore, the height or thickness of the described element is related to the stacking direction A, and the lateral direction B is oriented perpendicular to the stacking direction A (see Figures 1 and 2). 【0041】 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, which can provide a base plate, can be 2 to 5 mm and may be configured to dissipate heat from the metal substrate structure 3 and the semiconductor power module 10. The resin layer 18 may include 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 as a prepreg sheet assembled or laminated between the two metal layers 17 and 19. 【0042】 Alternatively or additionally, the metal substrate structure 3 comprises a resin layer 18 formed by molding, for example by injection, transfer, or compression molding. The resin in the resin layer may include inorganic fillers, ceramic materials such as AlN, Si3N4, BN, Al2O3, or SiO2. The bottom metal layer 19 may be made of or contain copper and / or aluminum and / or corresponding alloys. The circuit metallization formed by the top metal layer 17 may be made of or contain copper and / or aluminum and / or corresponding alloys. Furthermore, the top metal layer 17 may be partially or completely coated, and the corresponding coating of the circuit metallization may be made of or contain nickel and / or precious metals such as gold and / or silver, and / or other metals. 【0043】 The semiconductor power module 10 further comprises buffer structural elements formed as metal block elements 7 made of or containing copper, aluminum, and / or corresponding alloys, and / or other applicable conductive materials or metals. The metal block elements 7 are mounted on the upper surface 171 of the metal top layer 17 and configured to form projections for terminals 4 having a predetermined height H. The terminals 4 and the metal block elements 7 are connected by ultrasonic welding using an ultrasonic welding head 6, such that the metal block elements 7 are positioned between the metal top layer 17 and the terminals 4 and materially bonded to the terminals 4. 【0044】 The metal block element 7 is configured to form protrusions on the upper surface 171 of the metal top layer 17, which enable protection of the resin layer 18 from mechanical and thermal shocks during the ultrasonic welding process. The metal block element 7 can be formed as a separate element attached to the metal top layer 17 by a bonding layer 11 (see Figure 1). Alternatively, the metal block element 7 can be formed integrally with the metal top layer 17 (see Figure 2). Alternatively, the semiconductor power module 10 may comprise both a metal block element 7 formed as a separate element and one formed integrally with the metal top layer 17. For example, a separate metal block element 7 can be attached to an integral one. In each case, the metal block element 7 provides locally greater thickness or reinforcement of the circuit metallization of the metal top layer 17 at the location where the terminals 4 are to be attached. The metal block element 7 can be made of, or may include, copper, aluminum and / or corresponding alloys and / or corresponding alloys or any other applicable conductive material or metal. 【0045】 The metal block element 7 comprises a coating layer 8 positioned on or on the upper surface 71 of the metal block element 7, partially or completely covering the upper surface 71. Alternatively or additionally, the coating may be present on the lower surface of the metal block element 7, if formed as at least a separate element. The metal block coating 8 can improve the ultrasonic welding process and / or can be used for protection against oxidation, for example, but can also contribute to the secure and reliable mounting of the metal block element 7 onto the circuit metallization of the top metal layer 17 of the metal substrate structure 3. The metal block coating layer 8 can be made of or contain noble metals such as nickel, silver and / or gold, and / or other metals. Each coating can be formed to include a single layer or a stack of multiple layers. In this case, the metal block element 7 is formed as a separate element that can be connected to the top surface 171 of the top metal layer 17 by soldering, sintering, bonding, dry contact and / or other applicable joining methods. 【0046】 Terminal 4 can be made of copper, aluminum and / or corresponding alloys, or may contain them, and can serve as the main or auxiliary terminal of a semiconductor power module 10. Furthermore, terminal 4 may comprise a first coating layer 5 that partially or completely covers the upper surface 41 of terminal 4. Terminal 4 may further comprise a second coating layer 9 that partially or completely covers the lower surface 42 of terminal 4. The first and second coating layers 5, 9 can favorably influence the ultrasonic welding process and / or protect the surface of terminal 4 from oxidation, and may be made of or contain precious metals such as nickel, gold, silver and / or other metals. The lower second coating layer 9 may also be useful for mounting terminal 4 to a metal block element 7. 【0047】 The steps for attaching the terminal 4 to the metal substrate structure 3 can follow the flowchart shown in Figure 3. For example, according to the embodiment shown in Figure 1, in step S1, at least one terminal 4 is provided. The terminal 4 may be provided with first and / or second coating layers 5, 9 on its upper surface 41 and / or lower surface 42. 【0048】 In step S2, the metal substrate structure 3 is provided with an uppermost metal layer 17, a lowermost metal layer 19, and an insulating resin layer 18 placed between them. A coating layer may also be available at least locally on the surface of the metal substrate structure 3. 【0049】 In step S3, the metal block element 7 is provided, for example, as a separate element and bonded to the metallization of the top metal layer 17 at the intended terminal position to form a projection for the terminal 4 on the upper surface 171 of the top metal layer 17. Alternatively or additionally, the metal block element 7 may be formed integrally with the metallization of the top metal layer 17. The metal block element 7 may have a coating layer 8 on its upper surface 71. Alternatively or additionally, if formed as a separate element, a coating may be present on the back side of each metal block element 7. 【0050】 In a further step S4, the terminal 4 is welded to the metal block element 7, thereby bonding it to the top metal layer 17 of the metal substrate structure 3 by ultrasonic welding using the ultrasonic welding head 6. The welding process forms a welded joint between the terminal 4 and the metal block element 7, firmly bonding the terminal 4 and the metal block element 7 materially. 【0051】 When the metal block element 7 is formed integrally with the metal top layer 17 (see Figure 2), it realizes a given thicker portion of the circuit metallization of the metal top layer 17 having a predetermined thickness or height H. In this case, the metal block element 7 is provided and is already bonded to the metal top layer 17 in step S2, or even available. In this case, the projection is realized in the manufacturing of the metal top layer 17 itself. In step S3, the coating layer 8 can be provided, for example, on the upper surface 71 of the metal block element 7. This can also be realized in step 2, where the provided metal substrate structure 3 also has a coating layer. 【0052】 Circuit metallization or the placement of metal block elements 7 between the top metal layer 17 and the terminals 4 provides protection for the resin layer 18 and also allows for improvements in the ultrasonic welding process. The metal block elements 7 may have a thickness or height H from 0.3 mm to 2.0 mm. 【0053】 The described embodiments relate to ultrasonic welding of power and auxiliary terminals 4 on an insulating metal substrate or insulating metal base plate realized by a metal substrate structure 3. The insulating metal substrate can be prepared by lamination or molding techniques, for example, using a punched metal sheet for circuit metallization to form the top metal layer 17. Thus, it is also feasible on substrate structures based on alternative insulating metal substrate techniques, such as punched and molded metal substrates. The ultrasonic welding process is facilitated by a buffer structure including a metal block element 7 positioned between the top metallization of the insulating metal substrate and the base of the terminals 4. 【0054】 In contrast to conventional substrates based on ceramic insulating sheets, insulating metal substrates consist of a relatively thick metal base made mostly of aluminum or copper or corresponding alloys, an insulating sheet based on a resin material, and circuit metallization made of aluminum or copper or corresponding alloys. The resin material used in the insulating resin layer 18 is, for example, an epoxy resin containing a thermally conductive inorganic filler material. Such filler materials can consist of ceramic particles prepared from aluminum nitride (AlN), silicon nitride (Si3N4), boron nitride (BN), and / or aluminum oxide (Al2O3). 【0055】 The mechanical and thermal effects of the ultrasonic welding process on the resin insulating layer 17 are reduced or suppressed by the implementation of a buffer structure in the form of a metal block element 7 between the upper surface 171 of the metal substrate structure 3 and the base of the terminal 4. The welded connection is then prepared between the base of the terminal 4 and the metal block element 7, resulting in minimal mechanical stress and heat occurring at the metal block element and the terminal base, but little to no at the metal substrate structure 3 itself. The metal block element 7 is joined to the upper surface 171 of the circuit metallization of the top metal layer 17, for example, before ultrasonic welding of the main or auxiliary terminal 4. Soldering, bonding, sintering, dry contact, or any other applicable joining method may be used to fix the metal block element 7 onto the upper surface 171. Alternatively, the metal block element 7 may be joined to the upper surface 171 of the circuit metallization of the top metal layer 17 after ultrasonic welding of the main or auxiliary terminal 4 to the metal block element 7 to prevent mechanical impact on the insulating resin layer 18. 【0056】 Instead of using an additional metal block element 7 as a buffer structure as shown in Figure 1, specific modifications to the circuit metallization of the top metal layer 17 of the insulating metal substrate structure 3 are also possible. Here, the buffer structure between the circuit metallization and the base of the terminal 4 is realized by locally thicker substrate metallization at the location of the terminal 4 (see Figure 2). Similar to the first embodiment, the locally thickened portion of the circuit metallization also realizes an integrally formed metal block element 7. 【0057】 The embodiments shown in Figures 1 and 2 above represent the improved metal substrate structure 3, semiconductor power module 10, and manufacturing method, and therefore do not constitute a complete list of all embodiments. Actual arrangements and methods may differ from the embodiments shown, for example, with respect to the metal substrate structure 3 and semiconductor power module 10. [Explanation of symbols] 【0058】 Reference sign 1 Heatsink 2 Bonding layer 3 Metal substrate structure 4 terminals 41 Top view of terminal 42 terminals, bottom side 5. First coating layer 6. Ultrasonic welding head 7 Buffer structural elements / metal blocks / protrusions 71 Top surface of metal block element 8. Metal block coating layer 9. Second coating layer 10. Semiconductor Power Modules 11 Bonding layer 17. Top metal layer 171 Top surface of the uppermost metal layer 18 Resin layer 19. Bottom metal layer A Stacking direction B Horizontal Height of H buffer structure S(i) Steps of a method for manufacturing a metal substrate structure for a semiconductor power module

Claims

[Claim 1] A method for attaching terminals (4) to a metal substrate structure (3) for a semiconductor power module (10), At least one terminal (4) must be provided, The metal substrate structure (3) is provided with an uppermost metal layer (17), a lowermost metal layer (19), and an insulating resin layer (18) disposed between the uppermost metal layer (17) and the lowermost metal layer (19). A buffer structural element (7) is provided to form a projection for at least one terminal (4) and is coupled to the upper surface (171) of the uppermost metal layer (17), The buffer structural element (7) is positioned between the uppermost metal layer (17) and the at least one terminal (4), and the at least one terminal (4) is bonded to the at least one terminal (4) by ultrasonic welding using an ultrasonic welding head (6) that operates with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the at least one terminal (4), the buffer structural element (7), and / or the metal substrate structure (3). Includes, Providing and connecting the buffer structural element (7) means A metal block projection is provided that is integrally formed with the upper metal layer (17) and protrudes from the upper surface (171) of the upper metal layer (17). Includes, The buffer structure element (7) is provided with respect to an adjacent region of the upper surface (171) of the uppermost metal layer (17) in the stacking direction (A) of the metal substrate structure (3) and the at least one terminal (4), with a height (H) of more than 0.4 mm and less than or equal to 2.0 mm. [Claim 2] A method for attaching terminals (4) to a metal substrate structure (3) for a semiconductor power module (10), At least one terminal (4) must be provided, The metal substrate structure (3) is provided with an uppermost metal layer (17), a lowermost metal layer (19), and an insulating resin layer (18) disposed between the uppermost metal layer (17) and the lowermost metal layer (19). A buffer structural element (7) is provided to form a projection for at least one terminal (4) and is coupled to the upper surface (171) of the uppermost metal layer (17), The buffer structural element (7) is positioned between the uppermost metal layer (17) and the at least one terminal (4), and the at least one terminal (4) is bonded to the at least one terminal (4) by ultrasonic welding using an ultrasonic welding head (6) that operates with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the at least one terminal (4), the buffer structural element (7), and / or the metal substrate structure (3). Includes, Providing the buffer structure element (7) means The buffer structural element (7) is provided with a coating layer (8) on its upper surface (71) configured to face the lower surface (42) of at least one terminal (4) during ultrasonic welding, and / or a coating layer (11) on its lower surface configured to face the upper surface (171) of the uppermost metal layer (17) during ultrasonic welding. Includes, The buffer structure element (7) is provided with respect to an adjacent region of the upper surface (171) of the uppermost metal layer (17) in the stacking direction (A) of the metal substrate structure (3) and the at least one terminal (4), with a height (H) of more than 0.4 mm and less than or equal to 2.0 mm. [Claim 3] A method for attaching terminals (4) to a metal substrate structure (3) for a semiconductor power module (10), At least one terminal (4) must be provided, The metal substrate structure (3) is provided with an uppermost metal layer (17), a lowermost metal layer (19), and an insulating resin layer (18) disposed between the uppermost metal layer (17) and the lowermost metal layer (19). A buffer structural element (7) is provided to form a projection for at least one terminal (4) and is coupled to the upper surface (171) of the uppermost metal layer (17), The buffer structural element (7) is positioned between the uppermost metal layer (17) and the at least one terminal (4), and the at least one terminal (4) is bonded to the at least one terminal (4) by ultrasonic welding using an ultrasonic welding head (6) that operates with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the at least one terminal (4), the buffer structural element (7), and / or the metal substrate structure (3). Includes, The buffer structure element (7) is provided with respect to the adjacent region of the upper surface (171) of the uppermost metal layer (17) in the stacking direction (A) of the metal substrate structure (3) and the at least one terminal (4), with a height (H) of more than 0.4 mm and less than or equal to 2.0 mm. The buffer structure element (7) comprises a material having a yield strength greater than that of the material of at least one terminal (4) or the uppermost metal layer (17). [Claim 4] A method for attaching terminals (4) to a metal substrate structure (3) for a semiconductor power module (10), At least one terminal (4) must be provided, The metal substrate structure (3) is provided with an uppermost metal layer (17), a lowermost metal layer (19), and an insulating resin layer (18) disposed between the uppermost metal layer (17) and the lowermost metal layer (19). A buffer structural element (7) is provided to form a projection for at least one terminal (4) and is coupled to the upper surface (171) of the uppermost metal layer (17), The buffer structural element (7) is positioned between the uppermost metal layer (17) and the at least one terminal (4), and the at least one terminal (4) is bonded to the at least one terminal (4) by ultrasonic welding using an ultrasonic welding head (6) that operates with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the at least one terminal (4), the buffer structural element (7), and / or the metal substrate structure (3). Includes, The buffer structure element (7) is provided with respect to the adjacent region of the upper surface (171) of the uppermost metal layer (17) in the stacking direction (A) of the metal substrate structure (3) and the at least one terminal (4), with a height (H) of more than 0.4 mm and less than or equal to 2.0 mm. The buffer structure element (7) comprises a material having a melting point higher than the melting point of the material of at least one terminal (4) or the uppermost metal layer (17). [Claim 5] Providing and connecting the buffer structural element (7) means A separate metal block element is provided from the aforementioned uppermost metal layer (17), The metal block element is bonded to the upper surface (171) of the uppermost metal layer (17) by a bonding layer (11). The method according to any one of claims 2 to 4, including the method described in any one of claims 2 to 4. [Claim 6] The method according to any one of claims 1 to 4, wherein the buffer structural element (7) and the uppermost metal layer (17) are provided comprising at least one of copper, a copper alloy, aluminum, and an aluminum alloy. [Claim 7] Providing at least one terminal (4) means that A first coating layer (5) is provided on the upper surface (41) of the terminal (4) which is configured to face the ultrasonic welding head (6) during ultrasonic welding, and / or a second coating layer (9) is provided on the lower surface (42) which is configured to face the uppermost metal layer (17) of the metal substrate structure (3) during ultrasonic welding. The method according to any one of claims 1 to 4, including the method described in any one of claims 1 to 4. [Claim 8] The method according to claim 7, wherein at least one of the first coating layer (5) of the at least one terminal (4) and the second coating layer (9) of the at least one terminal (4) comprises nickel and / or silver and / or gold. [Claim 9] The method according to any one of claims 1 to 4, wherein the buffer structural element (7) is bonded to the uppermost metal layer (17) by at least one of soldering, sintering, bonding, and dry contact. [Claim 10] A metal substrate structure (3) having an uppermost metal layer (17), a lowermost metal layer (19), and an insulating resin layer (18) bonded between both the uppermost metal layer (17) and the lowermost metal layer (19), At least one terminal (4) and A buffer structural element (7) bonded to the upper surface (171) of the uppermost metal layer (17) forming a projection for the at least one terminal (4), wherein the at least one terminal (4) is bonded to the buffer structural element (7) by ultrasonic welding using an ultrasonic welding head (6) acting with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the at least one terminal (4), the buffer structural element (7), and / or the metal substrate structure (3), such that the buffer structural element (7) is materially bonded to the at least one terminal (4) positioned between the uppermost metal layer (17) and the at least one terminal (4) by a welded joint, Equipped with, The buffer structure element (7) is provided with respect to the adjacent region of the upper surface (171) of the uppermost metal layer (17) in the stacking direction (A) of the metal substrate structure (3) and the at least one terminal (4), with a height (H) of more than 0.4 mm and less than or equal to 2.0 mm. The buffer structure element (7) is provided with a metal block projection that is integrally formed with the upper metal layer (17) and protrudes from the upper surface (171) of the upper metal layer (17), in the semiconductor power module (10). [Claim 11] A metal substrate structure (3) having an uppermost metal layer (17), a lowermost metal layer (19), and an insulating resin layer (18) bonded between both the uppermost metal layer (17) and the lowermost metal layer (19), At least one terminal (4) and A buffer structural element (7) bonded to the upper surface (171) of the uppermost metal layer (17) forming a projection for the at least one terminal (4), wherein the at least one terminal (4) is bonded to the buffer structural element (7) by ultrasonic welding using an ultrasonic welding head (6) acting with at least one of an ultrasonic frequency in the range of 10 to 100 kHz, an amplitude in the range of 10 to 100 μm, and a mechanical pressure in the range of 100 to 1000 N acting on the at least one terminal (4), the buffer structural element (7), and / or the metal substrate structure (3), such that the buffer structural element (7) is materially bonded to the at least one terminal (4) positioned between the uppermost metal layer (17) and the at least one terminal (4) by a welded joint, Equipped with, The buffer structure element (7) is provided with respect to the adjacent region of the upper surface (171) of the uppermost metal layer (17) in the stacking direction (A) of the metal substrate structure (3) and the at least one terminal (4), with a height (H) of more than 0.4 mm and less than or equal to 2.0 mm. The semiconductor power module (10) comprises a buffer structure element (7) having a coating layer (8) on an upper surface (71) configured to face the ultrasonic welding head (6) during ultrasonic welding, and / or a coating layer (11) on a lower surface (42) configured to face the upper surface (171) of the uppermost metal layer (17) of the metal substrate structure (3) during ultrasonic welding. [Claim 12] The semiconductor power module (10) according to claim 11, wherein the buffer structure element (7) comprises metal block elements formed separately from the metal upper layer (17) or metal block protrusions formed integrally with the metal upper layer (17), each protruding from the upper surface (171) of the metal upper layer (17). [Claim 13] A semiconductor power module (10) according to any one of claims 10 to 12, wherein at least one of the at least one terminal (4) and the metal top layer (17) comprises a coating layer (5, 9) on each upper surface (41, 171) configured to face the ultrasonic welding head (6) during ultrasonic welding and / or on each lower surface (42) configured to face the metal top layer (17) of the metal substrate structure (3) during ultrasonic welding.

Images