Method and system for connecting terminal elements to a substrate

Abstract

In one embodiment, a method includes feeding a continuous wire including a plurality of segments into a first end of a channel, and further feeding through the channel formed in a sonotrode of a welding tool until the first end of the continuous wire protrudes from a second end of the channel opposite the first end of the channel, the plurality of sections are arranged in succession to form a continuous wire; welding the first end of the continuous wire to the substrate through an ultrasonic welding electrode; and severing a first section from the continuous wire, the first section comprising a first portion and a second portion, the first portion comprising a first end, the second portion directly adjoining and extending from the first portion, where a hardness of the second portion is greater than a hardness of the first portion at least during the step of soldering the first end of the continuous wire to the substrate.

Description

Technical Field

[0001] The present disclosure relates to methods and systems for connecting terminal elements to a substrate, and in particular to terminal elements for semiconductor modules. Background Art

[0002] A power semiconductor module arrangement typically includes at least one semiconductor substrate disposed within a housing. A semiconductor arrangement comprising a plurality of controllable semiconductor elements (e.g., two IGBTs in a half-bridge configuration) or uncontrollable semiconductor elements (e.g., an arrangement of diodes) is disposed on each of the at least one substrate. Each substrate typically includes a substrate layer (e.g., a ceramic layer), a first metallization layer deposited on a first side of the substrate layer, and a second metallization layer deposited on a second side of the substrate layer. The controllable semiconductor elements are mounted, for example, on the first metallization layer. The second metallization layer may optionally be attached to a base plate.

[0003] The semiconductor substrate and the components mounted thereon are typically electrically coupled to the exterior of the housing via terminal elements. Such terminal elements are mechanically and electrically coupled to the substrate or one or more components mounted thereon via a first end and extend from there through the housing to the exterior of the housing. The terminal elements are typically coupled to the substrate or other components of the power semiconductor module device via brazing, sintering, or welding techniques. The resulting connection should be stable, and the method used to form the connection should be fast, reliable, cost-effective, and implementable in a space-saving manner.

[0004] What is needed is a method and system for connecting terminal elements to a substrate in a quick, reliable, cost-effective, and space-saving manner. Summary of the Invention

[0005] A method includes feeding a continuous wire comprising a plurality of segments into a first end of a channel and further feeding through the channel formed in a sonotrode of a welding tool until a first end of the continuous wire protrudes from a second end of the channel opposite the first end of the channel; welding the first end of the continuous wire to a substrate by the sonotrode; and severing a first segment from the continuous wire, the first segment comprising a first portion and a second portion, the first portion comprising a first end, the second portion directly adjacent to and extending from the first portion, wherein a hardness of the second portion is greater than a hardness of the first portion at least during the step of welding the first end of the continuous wire to the substrate.

[0006] A system includes a sonotrode having a channel formed therethrough and a cutting tool, wherein the system is configured to: feed a continuous wire comprising a plurality of segments into a first end of the channel and further feed through the channel formed in the sonotrode until a first end of the continuous wire protrudes from a second end of the channel opposite the first end of the channel; weld the first end of the continuous wire to a substrate by the sonotrode; and sever a first segment from the continuous wire, the first segment comprising a first portion and a second portion, the first portion comprising a first end and the second portion directly adjacent to and extending from the first portion, wherein a hardness of the second portion is greater than a hardness of the first portion at least during the step of welding the first end of the continuous wire to the substrate.

[0007] The continuous wire includes a plurality of segments arranged successively to form the continuous wire, wherein each of the plurality of segments includes a first portion and a second portion directly adjacent to and extending from the first portion, wherein the second portion of each segment further directly adjacent to the first portion of the directly consecutive segment, for each of the plurality of segments, a hardness of the second portion is greater than a hardness of the first portion, and the first portion of each of the plurality of segments is configured to be attached to a substrate of the semiconductor module.

[0008] The present invention may be better understood with reference to the following drawings and descriptions. The components in the drawings are not necessarily drawn to scale, but emphasis is placed on illustrating the principles of the present invention. In addition, in the drawings, like reference numerals denote corresponding parts throughout the different views. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a cross-sectional view of a power semiconductor module device.

[0010] Figure 2 is a 3D view of a power semiconductor module.

[0011] Figure 3 A method for connecting a terminal element to a substrate is schematically shown.

[0012] Figure 4 A continuous conductive line formed from a plurality of segments is schematically shown.

[0013] Figure 5 A section of a continuous conductive line according to an embodiment of the present disclosure is schematically illustrated.

[0014] Figure 6 A section of a continuous conductive line according to a further embodiment of the present disclosure is schematically shown.

[0015] 7A to 7EA method for connecting a terminal element to a substrate according to an embodiment of the present disclosure is schematically illustrated.

[0016] Figure 8 A section of a continuous conductive line according to a further embodiment of the present disclosure is schematically shown.

[0017] Figure 9 A section of a continuous conductive line according to a further embodiment of the present disclosure is schematically shown.

[0018] Figures 10A to 10E A method for connecting a terminal element to a substrate according to a further embodiment of the present disclosure is schematically illustrated. DETAILED DESCRIPTION

[0019] In the following detailed description, reference is made to the accompanying drawings. The accompanying drawings show specific examples in which the present invention may be implemented. It should be understood that, unless expressly stated otherwise, the features and principles described with respect to the various examples may be combined with each other. In the specification and the claims, the designation of certain elements as "first element", "second element", "third element", etc. should not be understood as enumerative. On the contrary, such designations are only used to distinguish different "elements". That is, for example, the presence of a "third element" does not require the presence of a "first element" and a "second element". The wires or electrical connections described herein may be a single conductive element, or may include at least two separate conductive elements connected in series and / or in parallel. The wires and electrical connections may include metal and / or semiconductor materials and may be permanently conductive (i.e., non-switchable). The semiconductor body described herein may be made of (doped) semiconductor material and may be a semiconductor chip or included in a semiconductor chip. The semiconductor body has electrical connection pads and includes at least one semiconductor element having electrodes.

[0020] refer to Figure 1 , schematically shows a cross-sectional view of a power semiconductor module arrangement 100. The power semiconductor module arrangement 100 includes a housing 7 and a semiconductor substrate 10. The semiconductor substrate 10 includes a dielectric insulating layer 11, a (structured) first metallization layer 111 attached to the dielectric insulating layer 11, and a (structured) second metallization layer 112 attached to the dielectric insulating layer 11. The dielectric insulating layer 11 is disposed between the first metallization layer 111 and the second metallization layer 112.

[0021] Each of the first metallization layer 111 and the second metallization layer 112 can be composed of or include one of the following materials: copper; a copper alloy; aluminum; an aluminum alloy; or any other metal or alloy that remains solid during operation of the power semiconductor module device. The semiconductor substrate 10 can be a ceramic substrate, i.e., a substrate in which the dielectric insulating layer 11 is a ceramic (e.g., a thin ceramic layer). The ceramic can be composed of or include one of the following materials: aluminum oxide; aluminum nitride; zirconium oxide; silicon nitride; boron nitride; or any other dielectric ceramic. For example, the dielectric insulating layer 11 can be composed of or include one of the following materials: Al2O3, AlN, SiC, BeO, or Si3N4. For example, the substrate 10 can be a direct copper bonding (DCB) substrate, a direct aluminum bonding (DAB) substrate, or an active metal brazing (AMB) substrate. Furthermore, the substrate 10 can be an insulated metal substrate (IMS). For example, an insulated metal substrate typically includes a dielectric insulating layer 11 that includes a (filler) material such as epoxy or polyimide. For example, the material of the dielectric insulating layer 11 can be filled with ceramic particles. Such particles can include, for example, SiO2, Al2O3, AlN, or BN, and can have a diameter between about 1 μm and about 50 μm. The substrate 10 can also be a conventional printed circuit board (PCB) having a non-ceramic dielectric insulating layer 11. For example, the non-ceramic dielectric insulating layer 11 can be composed of or include a cured resin. In general, any of a variety of different substrates can be used, as long as they take the form of a structured conductive layer on top of an insulating layer.

[0022] The semiconductor substrate 10 is arranged in the housing 7 or below the housing 7. Figure 1 In the example shown, the semiconductor substrate 10 forms the ground surface of the housing 7, while the housing 7 itself only includes side walls and a cover. However, this is only an example. The housing 7 may also include a base surface, and the semiconductor substrate 10 is arranged on the base surface and inside the housing 7. According to another example, the semiconductor substrate 10 may be mounted on a base plate (not shown). In some power semiconductor module devices 100, more than one semiconductor substrate 10 is arranged on a single base plate. For example, the base plate may form the ground surface of the housing 7. The top of the housing 7 may be a separate cover or lid that can be removed from the side walls, or may be formed integrally with at least the side walls of the housing 7. In the latter case, the top and at least the side walls of the housing 7 may be formed as a single piece, so that the top cannot be removed from the side walls without destroying the housing 7.

[0023] One or more semiconductor bodies 20 may be arranged on the semiconductor substrate 10. Each semiconductor body 20 arranged on the semiconductor substrate 10 may include a diode, an IGBT (insulated gate bipolar transistor), a MOSFET (metal oxide semiconductor field effect transistor), a JFET (junction field effect transistor), a HEMT (high electron mobility transistor), or any other suitable controllable or non-controllable electronic component.

[0024] One or more semiconductor bodies 20 may form a semiconductor device on the semiconductor substrate 10. Figure 1 In FIG. 2 , only two semiconductor bodies 20 are shown by way of example. Figure 1 The second metallization layer 112 of the semiconductor substrate 10 is a continuous layer. Figure 1 In the example shown, the first metallization layer 111 is a structured layer. "Structured layer" means that the first metallization layer 111 is not a continuous layer, but includes grooves between different parts of the layer. Such grooves are Figure 1 . In this example, the first metallization layer 111 includes four different parts. Different semiconductor bodies 20 can be mounted to the same or different parts of the first metallization layer 111. Different sections of the first metallization layer may not have electrical connections or may be electrically connected to one or more other parts using known connection techniques (e.g., bonding wires 3). For example, the electrical connection 3 may also include a connection plate or a conductor track, to name a few. One or more semiconductor bodies 20 can be electrically and mechanically connected to the semiconductor substrate 10 via a conductive connection layer 30. For example, such a conductive connection layer can be a solder layer, a conductive adhesive layer, or a sintered metal powder (e.g., sintered silver powder) layer.

[0025] Figure 1 The power semiconductor module device 100 shown further comprises a terminal element 4. The terminal element 4 is electrically connected to the first metallization layer 111 and provides an electrical connection between the interior and the exterior of the housing 7. The terminal element 4 can be electrically connected to the first metallization layer 111 via a first end 41, while a second end 42 of the terminal element 4 protrudes from the housing 7. The terminal element 4 can be electrically contacted from the outside at its second end 42. For example, the second end 42 of the terminal element 4 can be connected to the printed circuit board 60. Figure 1 In the example shown, the printed circuit board 6 is arranged outside the housing 7, away from or in direct contact with and parallel to the cover or lid of the housing 7 (and parallel to the substrate 10). The printed circuit board 60 includes a plurality of through holes, and each of the plurality of terminal elements 4 protrudes through a different through hole of the plurality of through holes. A plurality of components, such as semiconductor bodies or any kind of active or passive components ( Figure 1The terminal element 4 may be used to electrically couple one or more components arranged on the printed circuit board 60 to one or more components inside the housing 7.

[0026] However, Figure 1 The terminal elements 4 shown are merely examples. The terminal elements 4 can be implemented in any other manner and can be arranged in any other position. For example, one or more terminal elements 4 can be arranged close to the side wall of the housing 7 or adjacent to the side wall of the housing 7. Any other suitable embodiment is possible. For example, the terminal elements 4 can be composed of or include a metal, such as copper, aluminum, gold, silver or any alloy thereof. The terminal elements 4 can be electrically and mechanically connected to the first metallization layer 111 of the semiconductor substrate 10 via a conductive connecting layer (not specifically shown for the terminal elements 4). For example, such a conductive connecting layer can typically be a solder layer, a conductive adhesive layer or a sintered metal powder (e.g., sintered silver powder) layer.

[0027] Conventional power semiconductor module devices 100 typically also include a casting compound 5. For example, the casting compound 5 can consist of or include silicone, or can be a rigid molding compound. The casting compound 5 can at least partially fill the interior of the housing 7, thereby covering the components and electrical connections arranged on the semiconductor substrate 10. The terminal elements 4 can be partially embedded in the casting compound 5. However, at least their second ends 42 are not covered by the casting compound 5 and protrude from the casting compound 5 through the housing 7 to the outside of the housing 7. The casting compound 5 is configured to protect the components and electrical connections inside the power semiconductor module device 100 (in particular the housing 7) from certain environmental conditions and certain mechanical damage.

[0028] Now refer to Figure 2 , schematically shows a three-dimensional view of a semiconductor module. Figure 2 In the example shown, the housing 7 includes a cover that includes a plurality of through holes 722. Each of the plurality of terminal elements 4 of the semiconductor module extends through a different through hole 722 among the plurality of through holes 722. By providing a plurality of through holes 722 in the housing 7, the housing 7 does not have to be customized, but can be flexibly used by different customers and for different designs. However, the terminal elements 4 must be accurately positioned on the substrate 10 so that they can be easily inserted into the corresponding through holes 722 when the semiconductor module is assembled. The terminal elements 4 also need to be precisely aligned with the through holes provided in the external printed circuit board. In addition, in order to be able to assemble the semiconductor module and keep the external printed circuit board 60 in the desired position, the terminal elements 4 need to be sufficiently stable.

[0029] On the other hand, it should be possible to attach the terminal elements 4 to the substrate 10 in a fast, reliable, cost-effective and space-saving manner. Some semiconductor modules are known to include hollow rivets attached to the substrate 10. Each terminal element 4 is inserted into a different rivet in the hollow rivet. In particular, the terminal element 4 is pressed into the corresponding rivet with a certain amount of force in order to form a reliable and stable connection. However, mounting the terminal elements 4 to the substrate 10 by means of hollow rivets (pin / rivet connection) may be cumbersome. In addition, the rivets take up a lot of space on the substrate 10 and increase the overall cost of the semiconductor module.

[0030] The individual terminal elements 4 can be provided by a strap or depot containing a plurality of separate and distinct terminal elements 4. One terminal element 4 can be removed from the strap or depot and connected to the substrate 10, for example, by brazing, sintering, or welding techniques. The strap or depot can then be realigned with the substrate 10 before the next terminal element 4 is removed and further connection processes are performed. This process can be cumbersome and requires a large amount of space.

[0031] refer to Figure 3 and Figure 4 Alternatively, the terminal element 4 can be provided by a continuous wire 88. The continuous wire 88 according to an embodiment of the present disclosure includes a plurality of segments 4 arranged sequentially to form the continuous wire 88, wherein each of the plurality of segments 4 includes a first portion 44 and a second portion 46 directly adjacent to and extending from the first portion 44, wherein the second portion 46 of each segment 4 further directly adjacent to the first portion 44 of the immediately adjacent segment 4. In other words, the plurality of first portions 44 and the plurality of second portions 46 are arranged alternately along the length of the continuous wire 88. The number of first portions 44 can be equal to the number of second portions 46. For each of the plurality of segments 4, the second portion 46 can have a greater hardness than the first portion 44. The first portion 44 of each of the plurality of segments 4 is configured to be attached to the substrate 10 of the semiconductor module. Once attached to the substrate 10, the segments 4 can be separated from the continuous wire 88, for example, by a cutting tool 96, and formed into the terminal element of the semiconductor module. Because the first portion 44 of the segments 4 is relatively soft, it can be attached to the substrate 10 in a quick, reliable, cost-effective, and space-saving manner. When the segment 4 is mounted to the substrate 10 and the substrate 10 is arranged in the housing 7, the second portion 46 extends through the interior of the housing 7 and extends to the exterior of the housing 7. Since the second portion 46 is relatively hard and rigid, it can be easily inserted into the through hole 722 in the housing 7 and is strong enough to be connected to the printed circuit board 60, for example, via its second end 42.

[0032] refer to Figure 5, schematically illustrates in more detail an exemplary segment 4 having its first portion 44 and second portion 46. The first portion 44 can have a uniform thickness d4 along its entire length l44, and the second portion 46 can have a uniform thickness d4 along its entire length l46. However, the continuous wire 88 can also include a plurality of cuts, each of which is arranged between two directly adjacent segments 4. That is, the first portion 44 can have a mostly uniform thickness d4 that decreases toward the end of the first portion 44 facing away from the second portion 46, and the second portion 46 can have a mostly uniform thickness d4 that decreases toward the end of the second portion 46 facing away from the first portion 44. The cuts formed between the different segments 4 of the continuous wire 88 allow for easy severing of the segments 4 once they are connected to the substrate 10. Furthermore, the cuts allow for clear identification of the end of one segment 4 and the beginning of the next.

[0033] The length l46 of the second portion 46 can be at least twice the length l44 of the first portion 44, at least five times the length l44, or at least ten times the length l44. In this way, the main portion of the resulting terminal element 4 is rigid and provides sufficient stability. Only a relatively short first portion 44 is required to form a stable connection between the terminal element 4 and the substrate 10. According to one example, the first portion 44 of the plurality of segments 4 is composed of a material different from the second portion 46. For example, the material forming the first portion 44 can be relatively soft compared to the material forming the second portion 46. According to one example, the second portion 46 is composed of copper, and the first portion 44 is composed of a copper alloy with a reduced hardness compared to pure copper. According to another example, the second portion 46 is composed of aluminum, and the first portion 44 is composed of an aluminum alloy with a reduced hardness compared to pure aluminum. Any other suitable metal or metal alloy can be used alternatively and can be combined in any suitable manner. According to other embodiments, the first portion 44 and the second portion 46 are composed of the same material, but have different hardnesses, as described in further detail below.

[0034] When the segment 4 is arranged on the substrate 10 and has been severed from the continuous wire 88, the second portion 46 of the segment 4 (terminal element) can be mechanically and electrically connected to the printed circuit board 60 in any suitable manner. For example, the segment 4 can be soldered to the printed circuit board 60. Figure 6Alternatively, the second portion 46 of each of the plurality of segments 4 may include a press-fit element 48. Press-fit element 48 is an element that can be compressed to a certain extent (e.g., in a horizontal direction x perpendicular to the length l46 of second portion 46) when inserted into a corresponding counterpart (e.g., a through-hole through printed circuit board 60). When compressed, press-fit element 48 forms a secure connection with its associated counterpart (e.g., a through-hole through printed circuit board 60). In this manner, a highly reliable connection can be formed between segment 4 (terminal element) and printed circuit board 60.

[0035] The segments 4 can be welded to the substrate 10, for example, to form a reliable connection between the segments 4 and the substrate 10. A system for connecting a terminal element to the substrate 10 according to an embodiment of the present disclosure includes a sonotrode 90 having a channel 92 formed therethrough and a cutting tool 96. 7A to 7E and Figures 10A to 10E 7 and 10 show alternative embodiments. The system is generally configured to feed a continuous wire 88 comprising a plurality of segments 4 into a first end of a channel 92 and further feed through the channel 92 formed in a sonotrode 90 until the first end of the continuous wire 88 protrudes from a second end of the channel 92 opposite the first end of the channel 92 (see, e.g., FIG. Figure 7A and 10A ), the plurality of segments 4 are arranged successively to form a continuous wire 88. The system is further configured to weld the first end of the continuous wire 88 to the substrate 10 by means of an ultrasonic welding electrode 90 (see, for example Figure 7C and 10B ), and subsequently severing the first segment 4 from the continuous wire 88, the first segment 4 comprising a first portion 44 including a first end and a second portion 46 directly adjacent to and extending from the first portion 44. The hardness of the second portion 46 is greater than the hardness of the first portion 44, at least during the step of welding the first end of the continuous wire 88 to the substrate 10. In the figure, the channel 92 is shown as extending centrally through the sonotrode 90. However, this is merely an example. The channel 92 may generally extend through the sonotrode 90 at any suitable location; for example, the channel 92 may alternatively extend along the exterior of the sonotrode 90.

[0036] As described above, first portion 44 can be composed of a different material than second portion 46, wherein the material of second portion 46 has a greater hardness than the material of first portion 44. That is, even before continuous wire 88 is fed through passage 92, the hardness of second portion 46 can be greater than the hardness of first portion 44. Alternatively or additionally, first portion 44 can be heated before being soldered to substrate 10 to reduce its hardness. For example, the system can include a heating element configured to heat first portion 44 of first segment 4 while continuous wire 88 is fed through passage 92. In this manner, the hardness of first portion 44 is reduced before being soldered to substrate 10. According to some examples, first portion 44 is composed of the same material as second portion 46, and the hardness of first portion 44 is reduced solely by heating first portion 44 before performing the soldering process. According to other examples, first portion 44 is composed of a different material than second portion 46, and the hardness of first portion 44 is additionally reduced by heating first portion 44 before performing the soldering process. According to yet further examples, the first portion 44 is composed of a different material than the second portion 46 , and no additional steps are performed to reduce the hardness of the first portion 44 prior to performing the welding process.

[0037] The softened first portion 44 can be pressed against the substrate 10 by the sonotrode 90 and can be deformed (e.g., compressed) to a certain extent during the welding process. When the first portion 44 of the segment 4 subsequently cools down again, it can be considered that a permanent connection between the segment 4 and the substrate 10 is formed. The sonotrode 90 can oscillate during the welding process (e.g., ultrasonic welding).

[0038] Cutting tool 96 (e.g., Figure 7D and Figure 10D According to one example, the cutting tool 96 may include a cutting edge 964 and a corresponding counterholder element 962 ( Figure 7D ). In this way, the segments 4 already mounted on the substrate 10 can be easily severed from the continuous wire 88. However, any other suitable embodiments are generally possible. The cutting tool 96 can be configured to sever the first segment 4 at the cut formed in the continuous wire 88 between the first segment 4 and the directly adjacent second segment 4.

[0039] The diameter d4 of the terminal element 4 may be relatively small (e.g., less than 2 mm). When a terminal element 4 having a relatively small diameter d4 is connected to the substrate 10, the resulting connection may be unstable and may be damaged during the life of the semiconductor module. Therefore, according to one example and as Figure 7A and Figure 7B, the system may further comprise a bending tool 94 configured to bend the first portion 44 after feeding the continuous wire 88 through the channel 92 and before soldering the first end of the continuous wire 88 to the substrate 10 so that the first portion 44 extends at least partially perpendicular to the second portion 46. In this manner, the contact area between the segment 4 and the substrate 10 is increased, resulting in a more stable connection. The bending tool 94 may be implemented in any suitable manner. Figure 7A and 7B In the example shown, the bending tool 94 comprises only a simple pressing element that presses against the first portion 44 when the first portion 44 protrudes from the channel 92, thereby bending it into the desired position. Alternatively, the corresponding retainer element 962 of the cutting tool 96 can itself force the first portion 44 to bend, thereby eliminating the need for a separate bending tool 94.

[0040] However, bending the first portion 44 in order to increase the contact area between the segment 4 and the substrate 10 is only an example. Figure 8 and Figure 9 Alternatively, the first portion 44 may comprise a tapered or T-shaped portion. In other words, the end of the first portion 44 facing away from the second portion 46 may have a locally increased diameter. The diameter d4 of the first portion 44 may increase towards its free end before optionally being reduced again to form the cutout. Figure 10B and 10C , when the segment 4 is welded to the substrate 10, the sonotrode 90 generally presses the segment 4 (i.e., the first portion 44) onto the substrate 10. That is, a normal force is introduced into the substrate 10. When pressed onto the substrate 10, the free end of the first portion 44 deforms, similar to Figure 10C That is, even though the diameter of the first portion 44 is reduced again toward the end facing away from the second portion 46 to form the notch, the end of the first portion 44 is deformed and compressed to a certain extent during the welding process so that the resulting contact surface is relatively large. Figure 10A and Figure 10B As schematically shown in FIG, the system may further include a retaining element 98 configured to securely retain segment 4 (i.e., second portion 46) during the welding step. The retaining element 98 may apply pressure (e.g., similar to a pair of pliers) on segment 4 or other segments of the continuous wire 88 to prevent it from moving out of a desired position during the welding step (i.e., when the sonotrode 90 vibrates). When the continuous wire 88 is secured in position by the retaining element 98, a force perpendicular to the substrate 10 may be received by the first portion 44, which may be at least partially disposed within the channel 92 through the sonotrode 90 during the welding process.

[0041] Once a connection has been made and a segment 4 has been severed from the continuous wire 88, the sonotrode 90 can be moved to another position relative to the substrate 10 in order to make a further connection. Instead of or in addition to moving the sonotrode 90, the substrate 10 can also be moved. According to some examples, the sonotrode 90 performs movement only in the vertical direction y, and the substrate 10 is realigned relative to the sonotrode 90 between two subsequent welding processes. Figure 7E and 10E Schematically shown in FIG. 1 is a sonotrode 90 that moves vertically away from the substrate 10 .

[0042] A method according to an embodiment of the present disclosure includes feeding a continuous wire 88 including a plurality of segments 4 into a first end of a channel 92 and further feeding through the channel 92 formed in a sonotrode 90 of a welding tool until the first end of the continuous wire 88 protrudes from a second end of the channel 92 opposite the first end of the channel 92, the plurality of segments 4 being arranged successively to form the continuous wire 88; welding the first end of the continuous wire 88 to a substrate 10 by the sonotrode 90; and severing a first segment 4 from the continuous wire 88, the first segment 4 including a first portion 44 including a first end and a second portion 46 directly adjacent to and extending from the first portion 44, wherein a hardness of the second portion 46 is greater than a hardness of the first portion 44 at least during the step of welding the first end of the continuous wire 88 to the substrate 10.

[0043] The method may further include heating the first portion 44 of the first segment 4 while the continuous wire 88 is fed through the passage 92, thereby reducing the hardness of the first portion 44. Alternatively, the wire may be heated prior to placement into the passage 92 and may even be produced with a hardened portion during manufacture of the continuous wire 88. Additionally or alternatively, the method may further include bending the first portion 44 after feeding the continuous wire 88 through the passage 92 and before soldering the first end of the continuous wire 88 to the substrate 10, such that the first portion 44 extends at least partially perpendicular to the second portion 46. Severing the first segment 4 from the continuous wire 88 may include severing the first segment 4 at a cut formed in the continuous wire 88 between the first segment 4 and a directly adjacent second segment 4. Instead of bending the first portion 44, the first portion 44 of the first segment 4 may also include a tapered or T-shaped portion forming the first end of the continuous wire 88, and wherein soldering the first end of the continuous wire 88 to the substrate 10 may include soldering the tapered or T-shaped portion to the substrate 10.

Claims

1. A method comprising: feeding a continuous wire (88) comprising a plurality of segments (4) into a first end of a channel (92) and further feeding it through the channel (92) formed in a sonotrode (90) of a welding tool until the first end of the continuous wire (88) protrudes from a second end of the channel (92) opposite the first end of the channel (92), the plurality of segments (4) being arranged successively to form the continuous wire (88); welding the first end of the continuous wire (88) to a substrate (10) via the sonotrode (90); and A first segment (4) is severed from the continuous wire (88), the first segment (4) comprising a first portion (44) including the first end and a second portion (46) directly adjacent to and extending from the first portion (44), wherein The second portion (46) has a greater hardness than the first portion (44) at least during the step of welding the first end of the continuous wire (88) to the substrate (10).

2. The method according to claim 1, further comprising: The first portion (44) of the first section (4) is heated while feeding the continuous wire (88) through the passage (92), thereby reducing the stiffness of the first portion (44).

3. The method according to claim 1 or 2, further comprising: After feeding the continuous wire (88) through the passage (92) and before soldering the first end of the continuous wire (88) to the substrate (10), the first portion (44) is bent so that the first portion (44) extends at least partially perpendicular to the second portion (46).

4. The method according to any one of claims 1 to 3, wherein Severing the first segment (4) from the continuous wire (88) includes severing the first segment (4) at a cut formed in the continuous wire (88) between the first segment (4) and an immediately adjacent second segment (4).

5. The method according to claim 1 or 2, wherein: The first portion (44) of the first section (4) further includes a tapered or T-shaped portion forming the first end of the continuous wire (88), and wherein welding the first end of the continuous wire (88) to the substrate (10) includes welding the tapered or T-shaped portion to the substrate (10).

6. A system for connecting a terminal element to a substrate (10), comprising: a sonotrode (90) having a channel (92) formed therethrough; and Cutting tool (96), wherein The system is configured to: feeding a continuous wire (88) comprising a plurality of segments (4) into a first end of the channel (92) and further through the channel (92) formed in the sonotrode (90) until the first end of the continuous wire (88) protrudes from a second end of the channel (92) opposite the first end of the channel (92), the plurality of segments (4) being arranged successively to form the continuous wire (88); welding the first end of the continuous wire (88) to a substrate (10) via the sonotrode (90); and A first segment (4) is severed from the continuous wire (88), the first segment (4) comprising a first portion (44) including the first end and a second portion (46) directly adjacent to and extending from the first portion (44), wherein The second portion (46) has a greater hardness than the first portion (44) at least during the step of welding the first end of the continuous wire (88) to the substrate (10).

7. The system according to claim 6, further comprising: A heating element is configured to heat the first portion (44) of the first section (4) when the continuous wire (88) is fed through the passage (92), thereby reducing the stiffness of the first portion (44).

8. The system according to claim 6 or 7, further comprising: A bending tool (94) is configured to bend the first portion (44) after feeding a continuous wire (88) through the passage (92) and before soldering the first end of the continuous wire (88) to the substrate (10) so that the first portion (44) extends at least partially perpendicular to the second portion (46).

9. The system according to any one of claims 6 to 8, wherein: The cutting tool (96) is configured to sever the first segment (4) at a cut formed in the continuous wire (88) between the first segment (4) and an immediately adjacent second segment (4).

10. A continuous wire (88) comprising a plurality of segments (4) arranged successively to form the continuous wire (88), wherein Each of the plurality of segments (4) includes a first portion (44) and a second portion (46) directly adjacent to and extending from the first portion (44), wherein: The second portion (46) of each segment (4) further directly adjoins the first portion (44) of the directly subsequent segment (4), For each of the plurality of segments (4), the second portion (46) has a harderness greater than the first portion (44), and The first portion (44) of each of the plurality of segments (4) is configured to be attached to a substrate (10) of a semiconductor module.

11. The continuous wire (88) of claim 10, further comprising a plurality of cutouts, each of the plurality of cutouts being arranged between two directly adjacent segments (4).

12. The continuous conductor (88) of claim 10 or 11, wherein the first portion (44) of the plurality of segments (4) is composed of a different material than the second portion (46).

13. The continuous conductor (88) according to any one of claims 10 to 12, wherein the first portion (44) of each of the plurality of segments (4) comprises a tapered or T-shaped portion.

14. The continuous wire (88) according to any one of claims 10 to 13, wherein The second portion (46) of each segment (4) of the plurality of segments (4) includes a press-fit element (48).

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