Joint connector, power module assembly, and method for attaching a first joint partner to a second joint partner.

Abstract

A joint (1) for attaching a first joint partner (2) to a second joint partner (3) is defined, the joint (1) comprising - a joint material (4) and - a metal interphase layer (5), the joint material (4) being positioned between the first joint partner (2) and the second joint partner (3), the metal interphase layer (5) being positioned between the joint material (4) and at least one of the first joint partner (2) and the second joint partner (3), and the metal interphase layer (5) having at least two regions including at least one first region (6) having a first height (8) and at least one second region (7) having a second height (9) having different heights from each other. Furthermore, a power module assembly (11) and a method for attaching the first joint partner (2) to the second joint partner (3) are defined.

Description

Technical Field

[0001] The present disclosure relates to a bonding connection for attaching a first bonding partner to a second bonding partner, a power module assembly, and a method for creating a bonding connection.

[0002] Embodiments of the present disclosure relate particularly to highly reliable bonding connections. Further embodiments of the present disclosure relate to module assemblies having such bonding connections and methods for creating such bonding connections.

Summary of the Invention

Means for Solving the Problems

[0003] This is achieved by the subject matter of the independent claims. Further embodiments are apparent from the dependent claims in the following description.

[0004] A bonding connection for attaching a first bonding partner to a second bonding partner will be described. Exemplarily, the bonding connection is formed within a power semiconductor module having at least one power semiconductor device. The term "power" herein and below refers, for example, to power semiconductor modules, power semiconductor devices and / or power semiconductor chips adapted to handle voltages above 100 V and / or currents above 10 A, for example up to a maximum of 10 kV and a maximum of 5,000 A.

[0005] The first joining partner comprises, for example, a first connecting portion, and / or the second joining partner comprises, for example, a second connecting portion. The first connecting portion and / or the second connecting portion are formed of a particularly conductive material. The first connecting portion and / or the second connecting portion comprises, for example, a metal or a metal alloy. Exemplarily, the first connecting portion and / or the second connecting portion comprises, for example, at least one of copper (Cu), aluminum (Al), and nickel (Ni). In particular, the first connecting portion and / or the second connecting portion comprises, for example, an alloy comprising at least two of the following materials: copper (Cu), aluminum (Al), and nickel (Ni).

[0006] In particular, the first connection portion is the metallization of the first bonding partner, and the second connection portion is the metallization of the second bonding partner. The metallization of the first bonding partner and / or the second bonding partner, i.e., the first connection portion and / or the second connection portion, may be, for example, a thin coating of back surface metallization of the chip, or a substrate metallization of, for example, bulk metal, or the entire back surface of the chip, or a portion of the surface of the substrate metallization. The substrate metallization may have at least locally additional coatings. In some cases, the connection portion may be a terminal leg or a clip bonding portion.

[0007] The first and second joining partners each extend within a principal extension plane, which extends laterally. The first and second joining partners are positioned opposite each other in a vertical direction perpendicular to the lateral direction. In particular, the first connecting portion faces the second connecting portion such that the first connecting portion is positioned opposite the second connecting portion in the vertical direction. Exemplaryly, in a plan view, the first connecting portion completely overlaps the second connecting portion laterally.

[0008] For example, in a plan view, at least one of the first and second connecting portions has a polygonal shape such as a circle, ellipse, or quadrilateral. The joint connecting portion, exemplary, has the same shape as the first and / or second connecting portions in a plan view. For example, in a plan view, the range of the shape of at least one of the first and second connecting portions is greater than or equal to the shape of the joint connecting portion.

[0009] According to one embodiment, the joint includes a joining material. The joining material is formed of a conductive material in particular. The joining material includes, for example, a metal or a metal alloy, or consists of them. The joining material includes, for example, at least one of tin (Sn), lead (Pb), silver (Ag), antimony (Sb), and copper (Cu). In particular, the joining material includes, or consists of, an alloy containing at least two of the following materials: tin (Sn), lead (Pb), silver (Ag), antimony (Sb), and copper (Cu). The joining material may include rare earth materials or further substances such as bismuth or indium to affect material properties such as wetting behavior and / or diffusion rate.

[0010] According to the embodiment, the joint connection portion includes a metal interphase layer. The metal interphase layer includes, for example, at least one of the metals of the joining material and at least one of the metals of one of the first connection portion or the second connection portion.

[0011] Exemplary, during the method steps for creating a joint, the joining material is heated such that it melts and wets each joint, forming a metallurgical bond. For example, atoms from the joining material and the joint diffuse across the interface between the joining material and the joint, forming an intermetallic phase layer. That is, the intermetallic phase layer comprises or consists of a metal alloy of at least one metal of the joining material and at least one metal of one of the first joint or the second joint.

[0012] According to the embodiment of the joint connection, the joining material is placed between the first joining partner and the second joining partner. In particular, the joining material is placed between the first connecting portion and the second connecting portion. That is, the first joining partner, the joining material, and the second joining partner are stacked on top of each other along a stacking direction oriented vertically.

[0013] According to the embodiment of the joint connection, the intermetallic phase layer is disposed between the joining material and at least one of the first joining partner and the second joining partner. In particular, the intermetallic phase layer is the interface region between the joining material and at least one of the first joining partner and the second joining partner. The intermetallic phase layer is, for example, in direct contact with the joining material. For example, the intermetallic phase layer is in direct contact with at least one of the first joining partner and the second joining partner.

[0014] According to the embodiment of the joint connection, the intermetallic phase layer has at least two regions, including at least one first region having a first height and at least one second region having a second height, the regions having different heights from each other. The heights are in the vertical direction of the intermetallic phase layer.

[0015] In particular, such different regions having a first height and a second height should not be compared to the roughness of the interface between the intermetallic phase layer and the bonding material, and the interface between the intermetallic phase layer and at least one of the first bonding partner and the second bonding partner. Such roughness of the corresponding interface is typically due to manufacturing tolerances. That is, the difference between the first height and the second height is greater than the roughness of the corresponding interface of the intermetallic phase layer. The roughness is typically in the range of up to a few microns.

[0016] In particular, the joint connection provides a mechanically stable conductive connection and / or thermally conductive connection between the first joint partner and the second joint partner.

[0017] Typically, soldering is a bonding technique commonly used in the assembly of power semiconductor devices and modules, for example, to bond a first bonding partner, i.e., a power semiconductor chip, to a second bonding partner, i.e., an insulating substrate, or vice versa, or to bond a substrate to a base plate. Generally, conventional reflow soldering remains the most widely used bonding technique. During the conventional soldering process, the conventional intermetallic phase layer is created by the interdiffusion of materials at the interface between the conventional bonding material, i.e., conventional solder, and the bonding partner. Such a conventional intermetallic phase layer has a uniform height, mainly in the vertical direction. "Mainly" means that there may be variations in height due to manufacturing tolerances.

[0018] However, the typical interface area between the substrate and the base plate is relatively large. This can lead to locally varying stress levels, for example, due to thermal cycling during operation. For instance, during thermal cycling, the thermomechanical stress at the corners of a conventional solder joint is significantly greater than that in the central region. The weakest region of a conventional solder joint is likely to be where the highest thermomechanical stress occurs.

[0019] In summary, such a joint connection with a metal interphase layer having first and second heights can offer, among other advantages, the following:

[0020] The height of the intermetallic layer affects the stress resistivity of the joint because, for example, the hardness of the intermetallic layer is improved compared to the bare joint material, and consequently affects reliability, especially during thermal cycling. Therefore, the intermetallic layer has a first region and a second region with different heights. As a result, the reliability of the solder joint against thermomechanical stress is locally enhanced by intentionally and locally varying the height of the intermetallic layer so that it is patterned.

[0021] Such patterned intermetallic layers improve the reliability of the joint connection against thermomechanical stress. In particular, the patterned intermetallic layers increase the local ultimate strength of the joint connection, especially in critical areas where maximum stress occurs, and therefore result in longer cycle times.

[0022] When multiple patterns of the first and second heights exist, a cracking process similar to hooking can occur, which can suppress stress-induced cracking and delamination, thereby improving reliability.

[0023] According to a further embodiment of the joint, the first height and the second height differ from each other by at least 50% in the vertical direction. Exemplarily, the first height is greater than the second height, and in particular at least 1.5 times greater than the second height. Alternatively, the second height is greater than the first height, and in particular at least 1.5 times greater than the first height.

[0024] For example, at least one of the first height and the second height is between 1 μm and 100 μm.

[0025] According to a further embodiment of the joint connection, the first region is located in the central region of the joint connection, and the second region is located in the peripheral region of the joint connection that at least partially surrounds the central region.

[0026] Exemplary, the central region is located at the center of mass of the joint and extends laterally toward at least one edge of the first and second joints. The peripheral region extends laterally along the edge region of the joint that defines the central region. The peripheral region partially or completely encloses the central region laterally.

[0027] The second region is located at least partially or completely within the peripheral region. For example, the second region frames the central region. The term "frame" should be understood as being non-restrictive with respect to the shape of the reinforcing structure.

[0028] According to a further embodiment of the bonding connection portion, the second region is formed from several parts spaced apart from each other in the lateral direction, and each part has a second height. Exemplarily, the parts of the second region each have a second height. The parts of the second region are, for example, spaced apart from each other in the lateral direction.

[0029] When the second height is smaller than the first height, the parts of the second region are laterally spaced apart from each other by the first region. That is, for example, the first region is arranged between the parts of the second region.

[0030] When the second height is greater than the first height, the parts of the second region are laterally spaced apart from each other by the bonding material and / or by at least one of the first connection portion and the second connection portion. That is, for example, the bonding material and / or at least one of the first connection portion and the second connection portion is arranged between the parts of the second region.

[0031] According to a further embodiment of the bonding connection portion, each part is arranged at a corner of the bonding connection portion. When the bonding connection portion, particularly at least one of the first connection portion and the second connection portion, has a polygonal shape in plan view, each part is arranged in the region of one corner of the polygonal shape.

[0032] According to a further embodiment of the bonding connection portion, at least one of the first region and the second region has a width of at least 100 μm in the lateral direction. The width is the minimum extent of each of the first region and the second region in the lateral direction.

[0033] According to a further embodiment of the bonding connection portion, the intermetallic layer includes a plurality of first regions having a first height and a plurality of second regions having a second height. Each of the first regions has the same first height, and each of the second regions has the same second height.

[0034] According to a further embodiment of the joint connection, the first and second regions are arranged laterally on the virtual grid points of the virtual grid. The virtual grid is used solely to clarify the positions of the first and second regions. The virtual grid is, for example, a regular one-dimensional or regular two-dimensional grid. If the virtual grid is a regular two-dimensional grid, the virtual grid is a polygonal grid such as a triangular grid, a quadrilateral grid, in particular a square grid, or a hexagonal grid.

[0035] According to a further embodiment of the joint connection, each first region is formed as a first stripe, and each second region is formed as a second stripe. When the first and second regions are arranged on virtual grid points of a regular one-dimensional grid, each first region is formed as a first stripe, and each second region is formed as a second stripe.

[0036] The stripe has a range of width and length in the transverse direction. The length extends along the main direction of the stripe's extension. The length is greater than the width, and in particular, the length is at least 20% or at least 50% greater than the width.

[0037] According to a further embodiment of the joint connection, the first stripe and the second stripe are arranged alternately with respect to each other in one of the transverse directions. In particular, the first stripe and the second stripe are arranged alternately with respect to each other along an alignment direction perpendicular to the main extending direction of the stripe.

[0038] According to a further embodiment of the joint, the first region is formed as a first quadrilateral, and the second region is formed as a second quadrilateral. Exemplarily, the first quadrilateral and / or the second quadrilateral each have the same extent in the lateral direction. In particular, the first quadrilateral and / or the second quadrilateral are squares each having the same side length.

[0039] According to a further embodiment of the joint, the first and second quadrilaterals are arranged alternately in the lateral direction such that each first quadrilateral has an adjacent side to one of the second quadrilaterals, and vice versa. That is, the first and second quadrilaterals form a checkerboard pattern.

[0040] According to a further embodiment of the joint, the first height continuously increases or decreases up to a second height. In particular, the intermetallic layer gradually increases from the first height to the second height, and the first and second heights are within the maximum and minimum range in the vertical direction.

[0041] According to a further embodiment of the joint, the first height and the second height vary periodically in one of the lateral directions, and the width of one period is at least 200 μm in the lateral direction. That is, if the joint includes several first and second regions arranged alternately along each other, the maximum directly adjacent height of the first region corresponding to the first height, and / or the minimum directly adjacent height of the second region corresponding to the second height, are each spaced at least 200 μm apart from each other in the lateral direction.

[0042] According to a further embodiment of the joint connection, the first height increases or decreases discontinuously to a second height. Exemplarily, the first height increases or decreases to a second height within the interface region between the first region and the second region. The interface region has, for example, a lateral width at least one order of magnitude smaller than the width of at least one of the first region and the second region. Exemplarily, in a side view, the intermetallic layer has a stepped shape in the directly adjacent regions of the first region and the second region.

[0043] In a further embodiment, the joint is at least one of a solder joint, a diffusion solder joint, and a sintered joint.

[0044] According to a further embodiment of a bonding connection for a power module assembly comprising a semiconductor chip, the first bonding partner and the second bonding partner comprise at least one of a substrate and a base plate, a substrate and a terminal, a semiconductor chip and a substrate, and a terminal or clip and a semiconductor chip.

[0045] A base plate, substrate, and / or terminals may be part of a power semiconductor module. The semiconductor chip is, in particular, a power semiconductor chip. Specifically, a first junction partner and a second junction partner are included in the power semiconductor module. In this case, at least one of the first junction partner and the second junction partner is formed on a power semiconductor chip.

[0046] For example, the first bonding partner may be a substrate and the second bonding partner may be a base plate, or the first bonding partner may be a substrate and the second bonding partner may be a terminal, or the first bonding partner may be a semiconductor chip and the second bonding partner may be a substrate, or vice versa.

[0047] Furthermore, this specification describes power module assemblies that may include the joint connections described herein. Thus, features related to joint connections are disclosed in relation to power module assemblies, and vice versa.

[0048] According to one embodiment, the power module assembly comprises a first bonding partner, in particular the first bonding partner described herein.

[0049] According to the embodiment, the power module assembly comprises a second bonding partner, in particular the second bonding partner described herein.

[0050] According to the embodiment, the power module assembly includes a connecting portion, in particular the connecting portion described herein.

[0051] According to an embodiment of the power module assembly, the joint connection includes a joining material and at least one metal interphase layer.

[0052] According to an embodiment of the power module assembly, the bonding material is placed between a first bonding partner and a second bonding partner.

[0053] According to an embodiment of the power module assembly, the intermetallic phase layer is placed between the bonding material and at least one of the first bonding partner and the second bonding partner.

[0054] According to an embodiment of the power module assembly, the intermetallic layer has at least two regions, including at least one first region having a first height and at least one second region having a second height, with heights different from each other.

[0055] According to a further embodiment of the power module assembly, the first bonding partner is a substrate and the second bonding partner is a power semiconductor device, or vice versa. That is, the power module assembly is, in particular, part of a power semiconductor module. The power semiconductor device may comprise a power semiconductor chip.

[0056] Exemplary, power semiconductor devices are electronic components configured to handle high levels of power as described above herein. Exemplary, power semiconductor devices are configured, by corresponding switching operations, to control and convert power, for example, from AC to DC or vice versa, or to change the frequency of voltage and / or current. Power semiconductor devices include, for example, at least one of the following: thyristors, power metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), high-electron-mobility transistors (HEMTs), and power diodes, or comprise them.

[0057] For example, a power semiconductor module comprises one or more power semiconductor devices, along with further components such as a substrate, a base plate, a heat sink, at least one terminal, and a control processing circuit.

[0058] For example, the junction can be located between two of the following entities of the power semiconductor module: the power semiconductor device, the substrate, the base plate, the heat sink, at least one terminal, and the control processing circuit.

[0059] Furthermore, a method for attaching a first joining partner to a second joining partner is described herein, thereby enabling or creating the joining connection described above. Thus, features related to the joining connection are also disclosed in relation to the method, and vice versa.

[0060] According to one embodiment of the method, a first joining partner and a second joining partner are provided.

[0061] According to an embodiment of the method, the bonding material is applied to a first bonding partner. The bonding material is applied, for example, to a first connecting portion.

[0062] According to one embodiment of the method, the second bonding partner is applied to the bonding material. That is, the first bonding partner, the bonding material, and the second bonding partner are stacked on top of each other in the stacking direction and are in direct contact with each other.

[0063] According to one embodiment of the method, an assembly comprising a first bonding partner, a bonding material, and a second bonding partner is heated so that a metallic interphase layer is created. During heating, the bonding material melts and wets, for example, the first bonding portion. During heating, atoms from the bonding material and the bonding portion diffuse across the interface between the bonding material and the first bonding portion.

[0064] In particular, the assembly is heated and then cooled, causing the molten material of the joining material to solidify, and the atoms of the joining material form a metallic interphase layer.

[0065] According to one embodiment of the method, the intermetallic layer is modified to have at least two regions, including at least one first region having a first height and at least one second region having a second height, with heights different from each other.

[0066] In other words, conventional joints prepared by existing standard solder alloys and / or standard soldering processes can also be manipulated to improve reliability. Furthermore, the proposed method can provide additional influence and deformation options to the soldering process through local manipulation of the joint, in addition to a standard reflow process with a defined temperature profile.

[0067] According to a further embodiment of the method, a local magnetic field is applied to one of at least two regions while the assembly is being heated, and the height of the intermetallic phase layer depends on the magnetic flux of the local magnetic field.

[0068] If magnetic flux is applied to a second region during heating and / or cooling of the assembly, the second height will be smaller than the first height. That is, the magnetic flux will reduce the diffusion rate.

[0069] According to a further embodiment of the method, while the assembly is being heated, a local current is applied to one of at least two regions, and the height of the intermetallic phase layer depends on the current density of the local current.

[0070] If a current is applied to a second region during heating and / or cooling of the assembly, the second height will be smaller than the first height. In other words, the current reduces the diffusion rate.

[0071] According to a further embodiment of the method, while the assembly is being heated, additional heat is applied to at least one of two regions, and the height of the metal interphase layer depends on the temperature of the heat. For example, the additional heat is applied by a local heat source or a local heat probe.

[0072] In lieu of, or in addition to, the application of additional heat, additional cooling is applied to at least one of the regions, and the height of the metallic interphase layer depends on the cooling temperature. For example, the additional cooling is applied by a local cooling source or local cooling probe.

[0073] According to a further embodiment of the method, the joining material comprises at least two material systems that are distinct from each other, corresponding to at least two regions to be created. For example, the material system of the joining material located in a first region of the intermetallic layer to be created is different from the material system of the joining material located in a second region of the intermetallic layer to be created. The material systems may differ in the proportion of substances contained in those substances and / or both material systems.

[0074] According to a further embodiment of the method, the bonding material comprises at least two maximum doping concentrations that are different from each other, corresponding to at least two regions to be created. For example, the maximum doping concentration of the bonding material located in a first region of the intermetallic layer to be created is different from the maximum doping concentration of the bonding material located in a second region of the intermetallic layer to be created.

[0075] Illustratively, the bonding material contains doping material up to the maximum doping concentration, which is 2% or less or 1% or less of the bonding material per unit volume. The doping material may be, for example, a rare earth material, or, for example, bismuth (Bi) or indium (In). Illustratively, the wettability and / or diffusion of the bonding material depends on the doping concentration.

[0076] If the maximum doping concentration is greater in the first region than in the second region, the height of the first region is greater than the height of the second intermetallic phase layer that is created, or vice versa.

[0077] Alternatively or additionally, the bonding material includes at least two doping materials that are different from each other, corresponding to at least two regions to be created. For example, the doping material of the bonding material located in a first region of the intermetallic layer to be created is different from the doping material of the bonding material located in a second region of the intermetallic layer to be created.

[0078] According to a further embodiment of the method, the joint surface of a first joining partner and / or the joint surface of a second joining partner include at least two metallization materials that are different from each other, corresponding to at least two regions to be created. For example, the metallization material of a first connecting portion located in a first region of the intermetallic layer to be created is different from the metallization material located in a second region of the intermetallic layer to be created.

[0079] In particular, at least two metallization materials may differ by at least one of the metals of the connecting portion described herein.

[0080] According to a further embodiment of the method, the first bonding surface of the first bonding partner and / or the second bonding surface of the second bonding partner include at least two surface roughnesses that are different from each other, corresponding to at least two areas to be created.

[0081] For example, the first joining surface of the first joining partner is the upper surface of the first connecting portion facing the second joining partner. Exemplaryly, the second joining surface of the second joining partner is the bottom surface of the second connecting portion facing the first joining partner.

[0082] For example, the surface roughness of the first bonding surface in the first region of the intermetallic layer being created is different from the surface roughness of the second region of the intermetallic layer being created. For example, the surface roughness may differ by at least 10% or at least 50%.

[0083] According to a further embodiment of the method, the first bonding surface of the first bonding partner and / or the second bonding surface of the second bonding partner include a diffusion barrier in a region corresponding to at least one of the two regions to be created. The diffusion barrier is applied, exemplary, by a coating process.

[0084] If a diffusion barrier is placed in a second region, when the assembly is heated, the second height will be less than the first height. That is, the diffusion barrier reduces or blocks diffusion in the second region, resulting in a reduction in the second height.

[0085] The attached drawings are included to provide further understanding. In the drawings, elements of the same structure and / or function may be referred to by the same reference numerals. Please understand that the embodiments shown in the drawings are illustrative and not necessarily drawn to a specific scale. [Brief explanation of the drawing]

[0086] [Figure 1] A schematic diagram of a joint connection according to an exemplary embodiment is shown. [Figure 2]A schematic diagram of the method steps for creating a joint according to an exemplary embodiment is shown. [Figure 3] A schematic diagram of the method steps for creating a joint according to an exemplary embodiment is shown. [Figure 4] A characteristic diagram showing the relationship between the height of the intermetallic phase layer in a joint according to an exemplary embodiment is shown. [Figure 5] A characteristic diagram showing the relationship between the height of the intermetallic phase layer in a joint according to an exemplary embodiment is shown. [Modes for carrying out the invention]

[0087] The joint 1 according to the exemplary embodiment in Figure 1 attaches a first joint partner 2 to a second joint partner 3. A jointing material 4 and a metal interphase layer 5 are arranged between the first joint partner 2 and the second joint partner 3. In particular, the metal interphase layer 5 includes or consists of the jointing material 4 and the material of the first joint portion 12. That is, the metal interphase layer 5 is partially located within the jointing material 4 and the first joint portion 12, and the height of the metal interphase layer 5 depends particularly on the wetting behavior and / or the diffusion rate, which will be described in more detail particularly in Figure 2.

[0088] The first joining partner 2 includes a first connecting portion 12, and the second joining partner 3 includes a second connecting portion 13. The first connecting portion 12 and the second connecting portion 13 are metallizations of their respective joining partners.

[0089] The first connecting portion 12, the intermetallic phase layer 5, the joining material 4, and the second connecting portion 13 are stacked on top of each other along the stacking direction, which is the vertical direction. The intermetallic phase layer 5 is located within the interface between the joining material 4 and the first connecting portion 12 and extends across the first region 6 and the second region 7.

[0090] The first region 6 is located in the central region of the joint connection 1, and the second region 7 is located in the peripheral region of the joint connection 1 that extends horizontally perpendicular to the vertical direction and completely encloses the central region. That is, in a plan view, the second region 7 completely encloses the first region 6 horizontally. The plan view corresponds to a diagram along the vertical direction of the joint connection 1.

[0091] The joint connection portion 1 has a first height 8 in the first region 6 and a second height 9 in the second region 7. The first height 8 is greater than the second height 9. The intermetallic phase layer 5 gradually increases in height from the second height 9 to the first height 8. In particular, the intermetallic phase layer 5 has a shape that corresponds to one of the periods shown in Figure 4, extending from one of the minimum values ​​to the directly adjacent minimum value. That is, the first height 8 corresponds to the maximum height of the first region 6, and the second height 9 corresponds to the minimum height of the second region 7.

[0092] The width of the first region 6 is, for example, at least 100 μm in the transverse direction.

[0093] The first joining partner 2 and the second joining partner 3, which are mechanically and stably connected by the joining connection part 1, constitute a power module assembly 11 according to an exemplary embodiment.

[0094] For example, the first bonding partner 2 is a substrate for a power semiconductor device, and the second bonding partner 3 is a power semiconductor device. In other words, the power module assembly 11 in this case is a power semiconductor module.

[0095] Exemplary power semiconductor devices include, or consist of, at least one of the following: thyristors, power metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), high electron mobility transistors (HEMTs), and power diodes.

[0096] According to the exemplary embodiment of Figure 2, an assembly comprising a first connecting portion 12, a joining material 4, and a second connecting portion 13 is heated to create a metallic interphase layer 5. Subsequently, the assembly is cooled. In particular, the joining connection portion 1 with the metallic interphase layer 5 is created by such a process as in the exemplary embodiment of Figure 1.

[0097] During heating and / or cooling of the assembly, a local magnetic field is applied to the second region 7. The magnetic flux of the local magnetic field applied to the second region 7 causes the diffusion rate in the second region 7 to decrease compared to the first region 6. Due to the decrease in the diffusion rate in the second region 7, the resulting second height 9 in the second region 7 is smaller than the resulting first height 8 in the first region 6.

[0098] According to the exemplary embodiment shown in Figure 3, the diffusion barrier 10 is positioned on the first joining surface of the first joining partner 2, the first joining surface of the first joining partner 2 being the upper surface of the first connecting portion 12 facing the second joining partner 3. The diffusion barrier 10 has varying heights, increasing from the edges of the first joining surface toward the central region of the first joining surface.

[0099] During heating and / or cooling of the assembly, the diffusion rate decreases in proportion to the height of the diffusion barrier 10. The diffusion rate is inversely proportional to the height of the diffusion barrier 10. That is, the resulting second height 9 in the intermetallic phase layer 5 of the second region 7 is greater than the resulting first height 8 in the first region 6.

[0100] In Figures 4 and 5, the y-axis indicates the height of the intermetallic phase layer 5, corresponding to the extent of the intermetallic phase layer 5 along one of the horizontal directions shown on the x-axis.

[0101] The intermetallic phase layer 5 shown in Figures 4 and 5 includes a plurality of first regions 6 having a first height 8 and a plurality of second regions 7 having a second height 9. The first regions 6 and the second regions 7 are arranged alternately in the lateral direction.

[0102] In Figure 4, the first height 8 decreases continuously, and particularly gradually, down to the second height 9. That is, in a side view, the intermetallic phase layer 5 has a sinusoidal shape consisting of multiple periods.

[0103] For example, the maximum values ​​of the sinusoidal waveform are spaced at least 200 μm apart laterally. That is, the period has a width of at least 200 μm.

[0104] The first height 8 and the second height 9 have the maximum height difference. The interface between the directly adjacent first region 6 and the second region 7 is at a height of the intermetallic phase layer 5 that corresponds, for example, to half of the maximum height difference.

[0105] In Figure 5, the first height 8 decreases discontinuously to the second height 9. That is, the first height 8 decreases to the second height 9 within the interface region between the first region 6 and the second region 7. In other words, in a side view, the intermetallic phase layer 5 has a stepped shape containing multiple periods.

[0106] For example, the first region 6 is separated laterally by a distance of at least 100 μm. That is, the lateral width of the first region 6 and the second region 7 is at least 100 μm each. [Explanation of Symbols]

[0107] Reference sign 1. Joint connection 2. First bonding partner 3. Second bonding partner 4 Bonding material 5 Intermetallic phase layer 6. First Domain 7. Second Domain 8. First height 9. Second height 10 Diffusion barrier 11 Power Module Assembly 12. First connection section 13. Second connection section

Claims

1. A joining connection part (1) for attaching a first joining partner (2) to a second joining partner (3), - Joining material (4), - comprising a metal interphase layer (5), - The joining material (4) is placed between the first joining partner (2) and the second joining partner (3), - The intermetallic phase layer (5) is disposed between the joining material (4) and at least one of the first joining partner (2) and the second joining partner (3). - The intermetallic phase layer (5) has at least two regions, including at least one first region (6) having a first height (8) and at least one second region (7) having a second height (9), wherein the intermetallic phase layer (5) has a joint connection (1).

2. - The first height (8) and the second height (9) differ from each other by at least 50% in the vertical direction. The joint connection part (1) according to claim 1.

3. - The first region (6) is located in the central region of the joint connection portion (1), and the second region (7) is located in the peripheral region of the joint connection portion (1) that at least partially surrounds the central region. The joining connection part (1) according to claim 1 or 2.

4. - The second region (7) is formed from several spaced portions, each portion having the second height, - Each part is positioned at the corner of the joint connection part (1), The joint (1) according to any one of claims 1 to 3.

5. - At least one of the first region (6) and the second region (7) has a width of at least 100 μm in the transverse direction. The joint connection part (1) according to any one of claims 1 to 4.

6. - The intermetallic phase layer (5) comprises a plurality of first regions (6) having the first height (8) and a plurality of second regions (7) having the second height (9). A connecting portion (1) according to any one of claims 1 to 5.

7. - The first region (6) and the second region (7) are arranged laterally on the virtual grid points of the virtual grid. The joint connection part (1) according to claim 6.

8. - The first region (6) is formed as a first stripe, and the second region (7) is formed as a second stripe. - The first stripe and the second stripe are arranged alternately with respect to one of the lateral directions. The joint connection portion (1) according to claim 6 or 7.

9. - The first region (6) is formed as a first quadrilateral, and the second region (7) is formed as a second quadrilateral. - The first quadrilateral and the second quadrilateral are arranged alternately in the lateral direction such that each first quadrilateral has an adjacent side to one of the second quadrilaterals. The joint connection portion (1) according to claim 6 or 7.

10. - The first height (8) continuously increases or decreases up to the second height (9), or - The first height (8) increases or decreases discontinuously up to the second height (9). A connecting portion (1) according to any one of claims 1 to 9.

11. - The first height (8) of the first region (6) and the second height (9) of the second region (7) change periodically in one of the lateral directions, and the width of one period is at least 200 μm in the lateral direction. The joint connection part (1) according to any one of claims 6 to 10.

12. The aforementioned joint connection portion (1) is - Solder connection part, - Diffusion solder joint, and - Sintered connection part A joint connection (1) according to any one of claims 1 to 11, which is at least one of the following.

13. A bonding connection (1) according to any one of claims 1 to 12 for a power module assembly comprising a semiconductor chip, wherein the first bonding partner (2) and the second bonding partner (3) are - Circuit board and base plate, - Circuit board and terminals, - Substrate and the semiconductor chip, and - Terminal or clip and the semiconductor chip A connecting portion (1) comprising at least one of the following.

14. A power module assembly (11), - The first joining partner (2), - The second joining partner (3), - comprising a connecting part (1), - The joint connection portion (1) includes a joining material (4) and at least one intermetallic phase layer (5), - The joining material (4) is placed between the first joining partner (2) and the second joining partner (3), - The intermetallic phase layer (5) is disposed between the joining material (4) and at least one of the first joining partner (2) and the second joining partner (3). - The power module assembly (11) has at least two regions, the intermetallic phase layer (5) comprising at least one first region (6) having a first height (8) and at least one second region (7) having a second height (9), the intermetallic phase layer (5) having a first height (8) and the intermetallic phase layer (5).

15. - The first bonding partner (2) is a substrate for power semiconductor devices, - The second bonding partner (3) is a power semiconductor device. The power module assembly (11) according to claim 14.

16. A method for attaching a first joining partner (2) to a second joining partner (3), - To provide a first joining partner (2) and a second joining partner (3), - Applying the bonding material (4) to the first bonding partner (2), - Applying the second joining partner (3) to the joining material (4), - Heating the assembly, which includes the first bonding partner (2), the bonding material (4), and the second bonding partner (3), so that a metallic interphase layer (5) is formed. - Modify the intermetallic phase layer (5) to have at least two regions, including at least one first region (6) having a first height (8) and at least one second region (7) having a second height (9), Methods that include...

17. While the aforementioned assembly is being heated, - A local magnetic field is applied to one of the at least two regions, and the height of the intermetallic phase depends on the magnetic flux of the local magnetic field. - A local current is applied to one of the at least two regions, and the height of the intermetallic phase depends on the current density of the local current. The method according to claim 16, wherein additional heat and / or additional cooling is applied to one of the at least two regions, and the height of the intermetallic phase depends on the temperature of the heat, the method according to claim 16.

18. - The joining material (4) includes at least two material systems that are different from each other, corresponding to the at least two regions to be created. - The bonding material (4) includes at least two maximum doping concentrations that are different from each other, corresponding to the at least two regions to be created. The method according to any one of claims 16 or 17, wherein the method is at least one of the following.

19. - The bonding surface of the first bonding partner (2) and / or the bonding surface of the second bonding partner (3) comprises at least two different metallization materials corresponding to the at least two regions to be created. - The first bonding surface of the first bonding partner (2) and / or the second bonding surface of the second bonding partner (3) include at least two surface roughnesses that are different from each other, corresponding to the at least two regions to be created. The method according to any one of claims 16 to 18, wherein at least one of the following is the method according to claim 16 to 18.

20. - The bonding surface of the first bonding partner (2) and / or the bonding surface of the second bonding partner (3) includes a diffusion barrier (10) in the region corresponding to at least one of the two regions to be created. The method according to any one of claims 16 to 19.

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