CONDUCTIVE PINS, POWER MODULES, ULTRASONIC WELDING SYSTEMS AND METHODS OF USE THEREOF

Abstract

A conductive pin for ultrasonic welding is provided. The conductive pin includes a body portion. The conductive pin also includes a pin head at one end of the body portion. The pin head defines a bonding surface configured to be ultrasonically welded to a workpiece. The bonding surface includes at least one of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

Description

REFERENCE TO ASSOCIATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 607,533, filed December 7, 2023, the contents of which are incorporated by reference into this application. FIELD OF EXPERTISE

[0002] The invention relates to ultrasonic welding and, more particularly, to improved systems and methods for performing ultrasonic welding operations, including the welding of conductive pins. BACKGROUND

[0003] Ultrasonic energy is commonly used to create bonds between two or more materials. For example, wire bonding systems (e.g., ball bonders, wedge bonders, ribbon bonders, etc.) are used to bond a wire or ribbon to a bond site. Wire bonding uses relatively small amounts of energy (e.g., bond force, ultrasonic energy, etc.). Exemplary wire bonding systems are marketed by Kulicke and Soffa Industries, Inc., in Fort Washington, Pennsylvania.

[0004] In certain applications, materials other than wire are joined. Welding has been considered for such applications. Ultrasonic welding is also a widely used technology. In ultrasonic welding, an ultrasonic converter (e.g., supporting a horn) can be used to convert electrical energy into mechanical motion / scrubbing (e.g., linear motion / scrubbing, torsional motion / scrubbing, etc.). However, existing ultrasonic welding technology and equipment are limited in their ability to provide solutions that can meet market demand in terms of cost, operational efficiency, flexibility, portability, and related factors.

[0005] U.S. Patent No. 10,882,134 (entitled "Ultrasonic Welding Systems and Methods of Use"), U.S. Patent No. 11,364,565 (entitled "Ultrasonic Welding Systems and Methods of Use"), and U.S. Patent Nos. 11,850,676 and 12,070,814 (entitled "Ultrasonic Welding Systems, Methods of Use, and Associated Workpieces Including Welded Conductive Pins") assigned to Kulicke and Soffa Industries, Inc., relate to improvements in ultrasonic welding technology and are incorporated by reference in their entirety.

[0006] Nevertheless, improvements are needed in ultrasonic welding applications, including ultrasonic welding of pins (where such pins are often soldered and / or press-fitted into power modules). Therefore, it would be desirable to improve ultrasonic welding technology, including ultrasonic welding of pins. SUMMARY

[0007] According to an exemplary embodiment of the invention, a conductive pin for ultrasonic welding is provided. The conductive pin includes a body portion. The conductive pin further includes a pin head at one end of the body portion. The pin head defines a bonding surface configured to be ultrasonically welded to a workpiece. The bonding surface includes at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

[0008] According to other embodiments of the invention, the conductive pin described in the immediately preceding paragraph may have one or more of the following features: the bonding surface comprises the non-planar surface; the non-planar surface is a curved surface; the curved surface has a radius of curvature between 2 mm and 100 mm; the bonding surface comprises the opening defined in the central region of the bonding surface; the opening has a maximum depth between 10 µm and 1000 µm; the opening extends over the entire length of the body portion of the conductive pin; the opening is a conical opening; the opening is a curved opening; the curved opening has a radius of curvature between 2 mm and 100 mm; the opening is a cylindrical opening; the non-planar surface is an angled surface;the angled surface is configured at an angle between 1 degree and 15 degrees with respect to a horizontal plane, the horizontal plane being perpendicular to a longitudinal direction of the fuselage section; and / or the bonding surface is configured to be ultrasonically welded to a workpiece using torsional vibrations.

[0009] According to another exemplary embodiment of the invention, a power module is provided. The power module comprises a semiconductor element. The power module also comprises a support member for supporting the semiconductor element. The power module also comprises at least one conductive pin ultrasonically welded to the support member. The conductive pin comprises a body portion and a pin head at one end of the body portion. The pin head defines a bonding surface that is welded to the support member. The bonding surface of the conductive pin, prior to ultrasonically welding to the support member, comprised at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

[0010] According to other embodiments of the invention, the power module mentioned in the immediately preceding paragraph may have one or more of the following features: the bonding surface included the non-planar surface before being ultrasonically welded to the support member; the non-planar surface was a curved surface; the curved surface had a radius of curvature between 2 mm and 100 mm; the bonding surface included the opening defined in the central region of the bonding surface before being ultrasonically welded to the support member; the opening had a maximum depth between 10 µm and 1000 µm; the opening extended over the entire length of the body portion of the conductive pin; the opening was a conical opening; the opening was a curved opening; the curved opening had a radius of curvature between 2 mm and 100 mm; the opening was a cylindrical opening; the non-planar surface was an angled surface;the angled surface was configured at an angle between 1 degree and 15 degrees with respect to a horizontal plane, the horizontal plane being perpendicular to a longitudinal direction of the fuselage section; and / or the bonding surface was configured to be ultrasonically welded to a workpiece using torsional vibrations.

[0011] According to another exemplary embodiment of the invention, an ultrasonic welding system is provided that is configured to weld a conductive pin to a workpiece. The ultrasonic welding system includes a sonotrode configured to ultrasonically weld the conductive pin to the workpiece during a welding operation. The ultrasonic welding system also includes a control system configured to control the welding operation, wherein the welding operation includes bonding a bonding surface of the conductive pin to the workpiece, the bonding surface including at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

[0012] According to other embodiments of the invention, the ultrasonic welding system described in the immediately preceding paragraph may include one or more of the following features: the control system is configured to apply process parameters based on the bonding surface during the welding process; the bonding surface includes the non-planar surface, the control system is configured to apply process parameters based on the non-planar surface during the welding process; the bonding surface includes the opening defined in the central region, the control system is configured to apply process parameters based on the opening defined in the central region during the welding process;the bonding surface includes the non-planar surface and the opening defined in the central region of the non-planar surface; the control system is configured to apply process parameters during the welding process based on the non-planar surface and the opening defined in the central region of the non-planar surface; the process parameters include at least one of bond force, bond energy, and bond duration; and / or the welding process utilizes torsional vibrations applied by the horn. It should further be understood that one or more of the conductive pin and / or power module features described in the preceding paragraphs of this summary may be used in conjunction with the ultrasonic welding system.

[0013] According to another exemplary embodiment of the invention, a method for ultrasonically welding a conductive pin to a workpiece is provided. The method comprises the following steps: (a) providing a workpiece; and (b) ultrasonically welding the conductive pin to the workpiece, wherein the conductive pin comprises a body portion and a pin head at one end of the body portion, the pin head defining a bonding surface configured to be ultrasonically welded to the workpiece, the bonding surface comprising at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

[0014] According to other embodiments of the invention, the method described in the immediately preceding paragraph may include one or more of the following features: Step (b) comprises applying process parameters using a control system during ultrasonic welding based on the bonding surface; Step (b) comprises applying process parameters using a control system during ultrasonic welding based on the non-planar surface; Step (b) comprises applying process parameters using a control system during ultrasonic welding based on the opening defined in the central region; Step (b) comprises applying process parameters using a control system during ultrasonic welding based on the non-planar surface and the opening defined in the central region of the non-planar surface;Step (b) comprises applying process parameters using a control system during ultrasonic welding, wherein the process parameters include at least one of bond force, bond energy, and bond duration; and / or step (b) comprises applying process parameters using a control system during ultrasonic welding, wherein the ultrasonic welding utilizes torsional vibrations applied by a horn configured to ultrasonically weld the conductive pin to the workpiece. Further, it should be understood that any feature of a conductive pin and / or a power module described in the preceding paragraphs of this summary may be used in conjunction with the ultrasonic welding system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily enlarged or reduced for clarity. Included in the drawings are the following figures: Fig. is a block diagram side view of an ultrasonic welding system according to an exemplary embodiment of the invention; Fig. are cross-sectional side views of conductive pins (or portions thereof) according to various exemplary embodiments of the invention; The Fig. are cross-sectional side views of conductive pins (or portions thereof) according to various exemplary embodiments of the invention; the Fig. are cross-sectional side views of conductive pins (or portions thereof) according to various exemplary embodiments of the invention; Fig. 5 is a block diagram side view of a power module according to an embodiment of the invention; and Fig. 6 is a flowchart of a method for ultrasonically welding a conductive pin to a workpiece according to various embodiments of the invention. DETAILED DESCRIPTION

[0016] Certain exemplary embodiments of the invention relate to ultrasonic welding systems and methods of using them, for example, in connection with conductive pins and / or power modules. Such ultrasonic welding systems can be used to weld conductive pins (and / or copper terminals or other conductive terminals) to a workpiece (e.g., a substrate, a support member, etc.).

[0017] Ultrasonic welding systems typically include an ultrasonic welding converter. Such converters can be designed, for example, for operation in a linear mode / linear motion or in a torsional mode / torsional motion. For example, a linear ultrasonic converter carries a sonotrode, and during operation, a contact portion of the sonotrode vibrates with ultrasound in a substantially linear motion. In contrast, a torsional ultrasonic converter carries a sonotrode, and during operation, the concave portion of the sonotrode vibrates with ultrasound in a substantially rotating / torsional motion.

[0018] Certain ultrasonic welding systems, such as pin welding machines, can be used to weld / bond conductive pins to a workpiece. Conventional bonding surfaces (i.e., the welded side) of conductive pins for ultrasonic welding are almost always essentially flat or planar surfaces with varying degrees of roughness. Conventional conductive pins typically have a bottom surface (the welded side) that has an essentially flat profile. During conventional torsion welding of pins, the center of the bonding surface of the conductive pin (i.e., a point coincident with the axis of rotation of the conductive pin and / or the horn) may not experience sufficient bonding energy. Consequently, the bonded interface between the conductive pin and the workpiece (e.g., a support member) may experience stress concentrations (e.g.,due to uneven or insufficient bonding), delamination, fatigue spots, poor conductivity, or other bonding problems. Certain aspects of the invention address such problems associated with conventional bonding surfaces of conductive pins.

[0019] According to certain aspects of the invention, a pin head of a conductive pin may have a bonding surface that is non-planar. The bonding surface may be considered to have a non-planar profile. Examples of non-planar profiles include, but are not limited to, a sloped profile, an angled profile, and a curved profile, which are described herein and / or within the scope of the invention. The non-planar bonding surface of the pin head may significantly improve the weld connection of the conductive pin.

[0020] According to certain aspects of the invention, a pin head of a conductive pin may have a bonding surface including an opening defined in a central region of the bonding surface.

[0021] With reference to the drawings, Fig. 1 illustrates an ultrasonic welding system 100. The ultrasonic welding system 100 is configured to ultrasonically weld a conductive pin (e.g., a conductive pin 108, 208, 308, 408 of FIGS. 1, 2A-2F, 3A-3F, or 4A-4D) to a workpiece (e.g., workpiece 102a1, 102a2, 102a3, a support member, etc.). The ultrasonic welding system 100 includes a workpiece feeder 102 for providing a workpiece 102a1, wherein the workpiece feeder 102 is configured to transport a plurality of workpieces 102a1 (e.g., the workpiece feeder 102 may be a magazine handling system capable of transporting a plurality of workpieces 102a1, or another feeding structure suitable for the application-specific workpiece, etc.).Example workpieces 102a1 transported by workpiece feeder 102 include semiconductor devices, power modules, support elements, power module components, lead frames, battery modules, etc. The workpieces 102a1 are transported (by any transport device that may be included in a material handling system 104, such as a gripper device) from workpiece feeder 102 to material handling system 104.

[0022] The material handling system 104 moves the workpiece 102a1 (e.g., using a conveyor, a gripper device, etc.) to a support structure 106. The support structure 106 supports the workpiece (now referred to as a clamped workpiece 102a2 when clamped against the support structure 106 with a workpiece clamp) during a welding operation. After the welding operation (described below with respect to a weld head assembly 112), the now-welded workpiece 102a3 is moved (e.g., using a conveyor, a gripper assembly, etc.) from a portion of the material handling system 104 downstream of the support structure 106 to a workpiece output feeder 110. The output workpiece feeder 110 is configured to receive welded workpieces 102a3 after processing by the weld head assembly 112.The output workpiece supply 110 may be a magazine handling system for carrying a plurality of welded workpieces 102a3 or other supply structure suitable for the application-specific workpiece.

[0023] The ultrasonic welding system 100 includes a welding head assembly 112. The welding head assembly 112 includes an ultrasonic transducer 112b carrying a sonotrode 116 and is movable along a plurality of substantially horizontal axes. In the Fig. 1, the welding head assembly 112 is configured to move along the x-axis and y-axis of the ultrasonic welding system 100. In the example shown in Fig. 1, the weld head assembly 112 is also configured to move along the z-axis of the ultrasonic welding system 100 and about a theta axis (Ø axis) of the ultrasonic welding system 100. Not all of these axes of motion are required in every application. Using the axes of motion of the weld head assembly 112, the sonotrode 116 can be moved to the correct welding positions relative to the clamped workpiece 102a2. A camera 114 is also provided (which can optionally be carried by the weld head assembly 112 or another part of the ultrasonic welding system 100) for imaging operations related to the alignment between the sonotrode 116 and the clamped workpiece 102a2, the alignment of the components of the clamped workpiece 102a2 itself, visual inspection of the welds after the welding operation, etc.

[0024] The horn 116 is shown connected to a vacuum 118 (e.g., a vacuum source). The horn 116 may define a vacuum channel (not shown) connected to a vacuum via a conduit 118a for receiving the conductive pin 108 from a conductive pin supply (not shown).

[0025] The sonotrode 116 is shown supporting the conductive pin 108 prior to an ultrasonic welding operation. A body portion 108a of the conductive pin 108 is shown disposed with the sonotrode 116. As will be known to those skilled in the art, the conductive pin 108 (and other conductive pins illustrated and / or described herein) is typically cylindrically symmetrical and / or has a round cross-section along its length. A pin head 108b (at a distal end of the body portion 108a) is shown disposed below the sonotrode 116. Details of the conductive pin 108 and the pin head 108b are described in the Fig. 2A-2F, 3A-3F and 4A-4D shown.

[0026] Ultrasonic welding system 100 is illustrated including a control system 120. Control system 120 is configured to control the welding process (e.g., welding conductive pin 108 to workpiece 102a1 / 102a2 / 102a3). The welding process includes ultrasonically welding a bonding surface of the conductive pin to the workpiece, wherein the bonding surface includes at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. In certain embodiments, control system 120 is configured to apply process parameters based on the bonding surface during the welding process.

[0027] In one example, if the bonding surface includes a non-planar surface, the control system may be configured to apply process parameters based on the non-planar surface during the welding process.

[0028] In another example, if the bonding surface includes an opening defined in the central region of the bonding surface, the control system may be configured to apply process parameters during the welding process based on the opening defined in the central region.

[0029] In another example, if the bonding surface includes the non-planar surface and the opening defined in the central region of the non-planar surface, the control system may be configured to apply process parameters during the welding process based on the non-planar surface and the opening defined in the central region of the non-planar surface.

[0030] The process parameters can include at least a selection of bond force, bond energy, and bond duration. The welding process can utilize torsional vibrations applied by the sonotrode.

[0031] Various types of workpieces can be welded using the ultrasonic welding system 100 (or other systems within the scope of the invention). Example workpieces include a power module, a lead frame, and a battery module.

[0032] It should be understood that the term "power module" (sometimes referred to as a power electronics module), as used herein, refers to a module for accommodating one or more power components (e.g., power semiconductor elements or devices). Examples of power components include MOSFETs, IGBTs, BJTs, thyristors, GTPs, and JFETs. Such a module typically also includes a support element (e.g., a power electronics substrate) for supporting the power components. Compared to discrete power semiconductors, power modules generally offer higher power density. As will be appreciated by those skilled in the art, the power modules shown in the drawings are simplified for clarity.

[0033] According to the invention, various types of ultrasonic motions can be imparted to a conductor (e.g., a conductive pin, a signal connector, a conductive terminal, a power connector, etc.). For example, the sonotrode can be configured to weld a conductor to a workpiece using at least a selection of linear ultrasonic motions and torsional ultrasonic motions.

[0034] Certain of these workpieces are configured to receive a conductive pin. For the purposes of this description, the term "conductive pin" is a conductive structure designed to be welded to a workpiece. The conductive pin may have a free end (after welding to a workpiece), and a body portion of the conductive pin may extend substantially vertically from a "welded" end to the free end. The cross-section of the conductive pin may be round, square, rectangular, or any desired shape. The term "conductive pin" also includes conductive receptacles or sleeves (e.g., tubular in shape like a rivet) in which the conductive receptacle / sleeve is ultrasonically welded to a workpiece and configured to receive another conductive element.According to certain example embodiments, the ultrasonic welding system 100 may include a conductive pin feeder configured to provide a plurality of conductive pins for welding using the sonotrode 116. Example configurations for the conductive pin feeder include: a grid arrangement (including columns and rows of conductive pins aligned in such a manner to facilitate pickup), a tray conveyor, a magazine, a reel, etc. Alternative configurations are conceivable. Such a conductive pin feeder may be configured to operate with a buffer system so that the pins are guided through a staging area where they can be picked up for welding.

[0035] Exemplary embodiments of the conductive pin 108 are shown in the Fig. 2A-2F, 3A-3F and 4A-4D as conductive pin 208, conductive pin 308 and conductive pin 408, respectively.

[0036] With particular reference to Figure 2A, the conductive pin 208 is illustrated. The conductive pin 208 includes a body portion 208a. The conductive pin 208 also includes a pin head 208b at a distal end (i.e., along the Z-axis) of the body portion 208a. The pin head 208b defines a bonding surface 208c configured to be ultrasonically welded to a workpiece. The bonding surface 208c includes at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface 208c. The longitudinal direction LD of the body portion 208a and the horizontal plane HP are illustrated; the horizontal plane HP is perpendicular to the longitudinal direction LD of the body portion 208a. Example ranges for the overall length (or height) of the conductive pin 208 (or any other conductive pin illustrated and / or described herein) are: 1 mm - 100 mm; and 3 mm - 30 mm.Other areas are conceivable.

[0037] The Fig. 2B-2F show various embodiments of the conductive pin 208, including pin heads 208b1, 208b2, 208b3, 208b4, and 208b5, respectively. Fig. 2B-2F, each respective pin head is shown with a width W1 and a curved surface (the bonding surface 208c) with a radius of curvature ρ1. Example ranges for W1 include: 0.5 mm - 10 mm; and 1 mm - 4 mm. Example ranges for the radius of curvature ρ1 are: 1 mm - 1000 mm; and 2 mm - 100 mm. Other ranges are conceivable.

[0038] With particular reference to Figure 2B, the pin head 208b1 is shown including the bonding surface 208c1. The bonding surface 208c1 includes a non-planar surface 208c1a; in particular, the non-planar surface 208c1a is a curved surface. The non-planar surface 208c1a has a radius of curvature of ρ1.

[0039] With reference to Fig. 2C, the pin head 208b2 is shown including the bonding surface 208c2. The bonding surface 208c2 includes a non-planar surface 208c2a; in particular, the non-planar surface 208c2a is a curved surface. The bonding surface 208c2 further includes an opening 208c2b defined in the central region of the bonding surface 208c2. In particular, the opening 208c2b is an angled opening 208c2b. The opening 208c2b is shown as a conical opening with a width W2, an angle of θ1, and a maximum depth of d1. An exemplary range for the width W2 is 0.1 mm - 3 mm. Exemplary ranges for the angle θ1 are: 60 - 170 degrees; and 90 - 120 degrees. Example ranges for d1 are: 10 µm - 1000 µm; and 1 µm - 3000 µm. Other ranges are conceivable.

[0040] With reference to Fig. 2D illustrates the pin head 208b3 including the bonding surface 208c3. The bonding surface 208c3 includes a non-planar surface 208c3a; in particular, the non-planar surface 208c3a is a curved surface. The bonding surface 208c3 further includes an opening 208c3b defined in the central region of the bonding surface 208c3. In particular, the opening 208c3b is a curved opening. The opening 208c3b is illustrated as a spherical cap opening or dome-shaped opening having a width W2, a radius of curvature ρ2, and a maximum depth d2. An example range of the width W2 is 0.1 mm - 3 mm. Example ranges for the radius of curvature ρ2 are: 2 mm - 100 mm; and 1 mm - 1000 mm. Example ranges for the maximum depth d2 are: 10 µm - 1000 µm; and 1 µm - 3000 µm. Other ranges are conceivable.

[0041] With reference to Fig. 2E shows the pin head 208b4 including the bonding surface 208c4. The bonding surface 208c4 includes a non-planar surface 208c4a; in particular, the non-planar surface 208c4a is a curved surface. The bonding surface 208c4 further includes an opening 208c4b defined in the central region of the bonding surface 208c4. In particular, the opening 208c4b is a cylindrical opening. The opening 208c4b is shown with a width W2 and a maximum depth d3. An exemplary range for the width W2 is between 0.1 mm and 3 mm. Exemplary ranges for the maximum depth d3 are: 10 µm - 1000 µm; and 1 µm - 3000 µm. Other ranges are conceivable. It should be understood that the opening 208c4b may be configured as a rectangular opening, oval opening, and other geometrically shaped openings.

[0042] With reference to Fig. 2F illustrates the pin head 208b5 including the bonding surface 208c5. The bonding surface 208c5 includes a non-planar surface 208c5a; in particular, the non-planar surface 208c5a is a curved surface. The bonding surface 208c5 further includes an opening 208c5b defined in the central region of the bonding surface 208c5. In particular, the opening 208c5b is a cylindrical opening. The opening 208c5b is illustrated as having a width W2 and extending a length (e.g., the full length) of the body portion 208a. An exemplary range for the width W2 is between 0.1 mm and 3 mm. Other ranges are conceivable. It is understood that the opening 208c5b may be implemented as a rectangular opening, oval opening, pyramid-shaped opening, and other geometrically shaped openings.

[0043] In relation to Fig. 3A, the conductive pin 308 is illustrated. The conductive pin 308 includes a body portion 308a. The conductive pin 308 also includes a pin head 308b at a distal end (i.e., along the Z-axis) of the body portion 308a. The pin head 308b defines a bonding surface 308c configured to be ultrasonically welded to a workpiece. The bonding surface 308c includes at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface 308c. The longitudinal direction LD of the body portion 308a and the horizontal plane HP are illustrated; the horizontal plane HP is perpendicular to the longitudinal direction LD of the body portion 308a.

[0044] The Fig. 3B-3F show various embodiments of the conductive pin 308, including pin heads 308b1, 308b2, 308b3, 308b4, and 308b5, respectively. Fig. 3B-3F, each respective pin head is shown with a width W1 and an angled bonding surface with an angle θ2. The angled surface is arranged at an angle θ2 to the horizontal plane HP. Example ranges for W1 are: 0.5 mm - 10 mm; and 1 mm - 4 mm. Example ranges for the angle θ2 are: 1-15 degrees; and 1-45 degrees. Other ranges are conceivable.

[0045] With particular reference to Figure 3B, the pin head 308b1 is shown including the bonding surface 308c1. The bonding surface 308c1 includes a non-planar surface 308c1a; in particular, the non-planar surface 308c1a is an angled surface. The non-planar surface 308c1a has an angle of θ2.

[0046] With reference to Fig. 3C illustrates the pin head 308b2 including the bonding surface 308c2. The bonding surface 308c2 includes a non-planar surface 308c2a; in particular, the non-planar surface 308c2a is an angled surface. The bonding surface 308c2 further includes an opening 308c2b defined in the central region of the bonding surface 308c2. In particular, the opening 308c2b is an angled opening. The opening 308c2b is illustrated as a conical opening having an angle of θ1, a width W2, and a maximum depth d1. Example ranges for the angle θ1 are: 60-170 degrees and 90-120 degrees. An example range for the width W2 is 0.1 mm-3 mm. Example ranges for the maximum depth d1 are: 10 µm–1000 µm and 1 µm–3000 µm. Other ranges are conceivable.

[0047] Referring now to Figure 3D, the pin head 308b3 is illustrated including the bonding surface 308c3. The bonding surface 308c3 includes a non-planar surface 308c3a; more specifically, the non-planar surface 308c3a is an angled surface. The bonding surface 308c3 further includes an opening 308c3b defined in the central region of the bonding surface 308c3. More specifically, the opening 308c3b is a curved opening. The opening 308c3b is illustrated as a spherical cap opening or dome-shaped opening having a radius of curvature ρ2, a width W2, and a maximum depth d2. Example ranges for the radius of curvature ρ2 include: 2 mm - 100 mm; and 1 mm - 1000 mm. An example range for the width W2 is 0.1 mm - 3 mm. Example ranges for the maximum depth d2 include: 10 µm - 1000 µm; and 1 µm - 3000 µm. Other ranges are conceivable.

[0048] With reference to Fig. 3E now shows the pin head 308b4 including the bonding surface 308c4. The bonding surface 308c4 includes a non-planar surface 308c4a; in particular, the non-planar surface 308c4a is an angled surface. The bonding surface 308c4 further includes an opening 308c4b defined in the central region of the bonding surface 308c4. In particular, the opening 308c4b is a cylindrical opening. The opening 308c4b is shown with a width W2 and a depth d3. An exemplary range for the width W2 is between 0.1 mm and 3 mm. Exemplary ranges for the depth of d3 are: 10 µm - 1000 µm; and between 1 µm - 3000 µm. Other ranges are conceivable. It should be understood that the opening 308c4b may be configured as a rectangular opening, oval opening, and other geometrically shaped openings.

[0049] With reference to Fig. 3F illustrates the pin head 308b5 including the bonding surface 308c5. The bonding surface 308c5 includes a non-planar surface 308c5a; more specifically, the non-planar surface 308c5a is an angled surface. The bonding surface 308c5 further includes an opening 308c5b defined in the central region of the bonding surface 308c5. More specifically, the opening 308c5b is a cylindrical opening. The opening 308c5b is illustrated as having a width W2 and extending a length (e.g., the full length) of the body portion 308a. An exemplary range for the width W2 is between 0.1 mm and 3 mm. Other ranges are contemplated. It should be understood that the opening 308c5b may be configured as a rectangular opening, an oval opening, a pyramidal opening, and other geometrically shaped openings.

[0050] With reference to Fig. 4A, the conductive pin 408 is shown. The conductive pin 408 includes a body portion 408a. The conductive pin 408 also includes a pin head 408b at a distal end (i.e., along the Z-axis) of the body portion 408a. The pin head 408b defines a bonding surface 408c configured to be ultrasonically welded to a workpiece. The bonding surface 408c includes at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface 408c. The longitudinal direction LD of the body portion 408a and the horizontal plane HP are shown; the horizontal plane HP is perpendicular to the longitudinal direction LD of the body portion 408a.

[0051] The Fig. 4B-4D show various embodiments of the conductive pin 408 including the pin heads 408b1, 408b2, and 408b3, respectively. Fig. 4B-4D, each pin head is shown with a width W1. Example ranges for the width W1 are: 0.5 mm - 10 mm; and 1 mm - 4 mm. Other ranges are conceivable.

[0052] Referring now to Figure 4B, the pin head 408b1 including the bonding pad 408c1 is shown. The bonding pad 408c1 includes an opening 408c1a defined in the central region of the bonding pad 408c1. In particular, the opening 408c1a is a tapered opening. The opening 408c1a is shown as a conical opening having an angle of θ1, a width W2, and a maximum depth d1. Example ranges for the angle θ1 are: 60-170 degrees and 90-120 degrees. An example range for the width W2 is 0.1 mm-3 mm. Example ranges for the maximum depth d1 are: 10 µm-1000 µm and between 1 µm-3000 µm. Other ranges are conceivable.

[0053] Referring now to Figure 4C, the pin head 408b2 is illustrated including the bonding pad 408c2. The bonding pad 408c2 includes an opening 408c2a defined in the central region of the bonding pad 408c2. In particular, the opening 408c2a is a curved opening. The opening 408c2a is illustrated as a spherical opening or dome-shaped opening having a radius of curvature ρ2, a width W2, and a maximum depth d2. Example ranges for the radius of curvature ρ2 are: 2 mm - 100 mm; and 1 mm - 1000 mm. An example range for the width W2 is 0.1 mm - 3 mm. Example ranges for the maximum depth d2 are: 10 µm - 1000 µm; and between 1 µm - 3000 µm. Other areas are conceivable.

[0054] With reference to Fig. 4D illustrates the pin head 408b3 including the bonding pad 408c3. The bonding pad 408c3 includes an opening 408c3a defined in the central region of the bonding pad 408c3. In particular, the opening 408c3a is a cylindrical opening. The opening 408c3a is illustrated with a width W2 and a maximum depth d3. An exemplary range for the width W2 is between 0.1 mm and 3 mm. Exemplary ranges for the maximum depth d3 include: 10 µm - 1000 µm; and 1 µm - 3000 µm. Other ranges are conceivable. It is understood that the opening 408c3a may be embodied as a rectangular opening, pyramid-shaped opening, oval opening, and other geometrically shaped openings.

[0055] In the Fig. 2C-2F, 3C-3F, and 4B-4D, the various openings are illustrated and described throughout as geometric shapes, such as conical openings, dome-shaped openings, cylindrical openings, etc. It should be understood that these descriptions are exemplary in nature and are not intended to limit the scope of the embodiments. For example, the "conical" openings in FIGS. 2C, 3C, and 4B are intended to include similar openings, such as a frustoconical opening, an asymmetric conical opening, and the like. In another example, the "spherical cap / dome-shaped" openings of FIGS. 2D, 3D, and 4C are intended to include similar openings, such as a spheroidal (or spheroidal) opening, an asymmetrical sphere-like opening, and the like.

[0056] It is understood that the conductive pins described herein may be made of a copper material. While conductive pins (and terminals and busbars) made of copper (or a copper alloy) are described herein, it is understood that the invention (and the associated terminals, busbars, and methods) are not limited to copper materials. The conductive pins may be made of other conductive materials, such as aluminum.

[0057] With reference to Fig. 5, a power module 122 (a particular type of workpiece) is illustrated. The power module 122 includes a semiconductor element 102. As used herein, the term "semiconductor element" shall refer to any structure that includes (or is configured to include at a later time) a semiconductor die or chips (e.g., a power semiconductor element). Example semiconductor elements include, but are not limited to, a substrate (e.g., a leadframe, a circuit board, a carrier element, etc.), a substrate supporting one or more semiconductor chips, a bare semiconductor die, a packaged semiconductor device, a flip-chip semiconductor device, a die embedded in a substrate, a stack of semiconductor chips. In addition, the semiconductor element may include an element configured to be bonded or otherwise contained within a semiconductor package (e.g.,a spacer to be bonded in a stacked chip configuration, a substrate, etc.).

[0058] The power module 122 also includes a support member 124 for supporting the semiconductor element 102. The power module 122 also includes at least one conductive pin 108 (e.g., conductive pin 208 of the Fig. 2A-2F, conductive pin 308 of the Fig. 3A-3F and / or conductive pin 408 of the Fig. 4A-4D) ultrasonically welded to the support member 124. The conductive pin 108 includes a body portion 108a and a pin head 108b at one end of the body portion 108a. Prior to ultrasonic welding, the pin head 108b included a bonding surface configured to be ultrasonically welded to a workpiece (e.g., support member 124). The bonding surface of the conductive pin 108, prior to ultrasonic welding to the support member, included at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

[0059] In Fig. 5 shows the conductive pin 108 connected to the support member 124. It is understood that Fig. 5 shows a very simplified form of the power module 122; details are omitted for simplicity.

[0060] Fig. Figure 6 is a flowchart illustrating a method for ultrasonically welding a conductive pin to a workpiece. As will be appreciated by those skilled in the art, certain steps included in the flowchart may be omitted; certain additional steps may be added; and the order of the steps may be changed from the illustrated order—all within the scope of the invention.

[0061] In step 600, a workpiece (e.g. workpiece 102a1 / 102a2 / 102a3 of Fig. 1, support element 124 of Fig. 5) provided.

[0062] In step 602, a conductive pin (e.g., conductive pin 108 of Fig. 1, conductive pin 208 of Fig. 2A-2F, conductive pin 308 from Fig. 3A-3F, conductive pin 408 from Fig. 4A-4D) is ultrasonically welded to the workpiece. The conductive pin includes a body portion and a pin head at one end of the body portion. The pin head defines a bonding surface configured to be ultrasonically welded to a workpiece, the bonding surface including at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface.

[0063] In certain embodiments, step 602 includes applying process parameters using a control system (e.g., control system 120 of Fig. 1) during ultrasonic welding based on the bonding surface.

[0064] In certain embodiments, step 602 includes applying process parameters using a control system (e.g., control system 120 of Fig. 1) during ultrasonic welding based on the non-flat surface.

[0065] In certain embodiments, step 602 includes applying process parameters using a control system (e.g., control system 120 of Fig. 1) during ultrasonic welding based on the opening defined in the central area.

[0066] In certain embodiments, step 602 includes applying process parameters using a control system (e.g., control system 120 of Fig. 1) during ultrasonic welding based on the non-flat surface and the opening defined in the central area of ​​the non-flat surface.

[0067] In certain embodiments, step 602 includes applying process parameters using a control system (e.g., control system 120 of Fig. 1) during ultrasonic welding, wherein the process parameters include at least a selection of bond force, bond energy and bond duration.

[0068] In certain embodiments, step 602 includes applying process parameters using a control system (e.g., control system 120 of Fig. 1) during ultrasonic welding, where ultrasonic welding utilizes torsional vibrations applied by a sonotrode configured to ultrasonically weld the conductive pin to the workpiece during a welding process.

[0069] Although the invention is shown and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various changes in the details may be made within the scope and range of equivalents of the claims without departing from the invention.

[0070] Preferred embodiments of the present invention, in particular as described above, can be realized according to the points listed below, advantageously in combination with one or more of the features described above or according to the claims set out below, as described in the numbered variants and / or embodiments. 1. A conductive pin for ultrasonic welding, the conductive pin comprising: a fuselage section; and a pin head at one end of the body portion, the pin head defining a bonding surface configured to be ultrasonically welded to a workpiece, the bonding surface comprising at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. 2. The conductive pin according to embodiment 1, wherein the bonding surface has the non-planar surface. 3. The conductive pin according to embodiment 2, wherein the non-planar surface is a curved surface. 4. The conductive pin according to embodiment 3, wherein the curved surface has a radius of curvature between 2 mm and 100 mm. 5. The conductive pin according to embodiment 3, wherein the bonding surface further has the opening defined in the central region of the bonding surface. 6. The conductive pin according to embodiment 5, wherein the opening has a maximum depth between 10 µm and 1000 µm. 7. The conductive pin according to embodiment 5, wherein the opening extends over the entire length of the body portion of the conductive pin. 8. The conductive pin according to embodiment 5, wherein the opening is a conical opening. 9. The conductive pin according to embodiment 5, wherein the opening is a curved opening. 10. The conductive pin of embodiment 9, wherein the curved opening has a radius of curvature between 2 mm and 100 mm. 11. The conductive pin according to embodiment 5, wherein the opening is a cylindrical opening. 12. The conductive pin of embodiment 2, wherein the non-planar surface is an angled surface. 13. The conductive pin of embodiment 12, wherein the angled surface is configured at an angle between 1 degree and 15 degrees with respect to a horizontal plane, the horizontal plane being perpendicular to a longitudinal direction of the body portion. 14. The conductive pin of embodiment 12, wherein the bonding surface further has the opening defined in the central region of the bonding surface. 15. The conductive pin of embodiment 14, wherein the opening has a maximum depth between 10 µm and 1000 µm. 16. The conductive pin of embodiment 14, wherein the opening extends the entire length of the body portion of the conductive pin. 17. The conductive pin of embodiment 14, wherein the opening is a conical opening. 18. The conductive pin of embodiment 14, wherein the opening is a curved opening. 19. The conductive pin of embodiment 14, wherein the opening is a cylindrical opening. 20. The conductive pin according to embodiment 1, wherein the bonding surface includes the opening defined in the central region of the bonding surface. 21. The conductive pin of embodiment 20, wherein the opening is a conical opening. 22. The conductive pin of embodiment 20, wherein the opening is a curved opening. 23. The conductive pin of embodiment 22, wherein the curved opening has a radius of curvature between 2 mm and 100 mm. 24. The conductive pin of embodiment 20, wherein the opening is a cylindrical opening. 25. The conductive pin of embodiment 20, wherein the opening has a maximum depth between 10 µm and 1000 µm. 26. The conductive pin of embodiment 1, wherein the bonding surface is configured to be ultrasonically welded to a workpiece using torsional vibrations. 27. A performance module comprising: a semiconductor element; a support member for supporting the semiconductor element; and at least one conductive pin ultrasonically welded to the support member, the conductive pin having a body portion and a pin head at one end of the body portion, the pin head defining a bonding surface welded to the support member, wherein the bonding surface of the conductive pin prior to ultrasonic welding to the support member has at least one of the following features: (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. 28. The power module according to embodiment 27, wherein the bonding surface has the non-planar surface prior to ultrasonic welding to the support element. 29. The power module of embodiment 28, wherein the non-planar surface is a curved surface. 30. The power module of embodiment 29, wherein the curved surface has a radius of curvature between 2 mm and 100 mm. 31. The power module of embodiment 28, wherein the bonding pad further comprises the opening defined in the central region of the bonding pad before being ultrasonically welded to the support member. 32. The power module of embodiment 31, wherein the opening has a maximum depth between 10 µm and 1000 µm. 33. The power module of embodiment 31, wherein the opening extends the entire length of the body portion of the conductive pin. 34. The power module of embodiment 31, wherein the opening is a conical opening. 35. The power module of embodiment 31, wherein the opening is a curved opening. 36. The power module of embodiment 35, wherein the curved opening has a radius of curvature between 2 mm and 100 mm. 37. The power module of embodiment 31, wherein the opening was a cylindrical opening. 38. The power module of embodiment 28, wherein the non-planar surface was an angled surface. 39. The power module of embodiment 38, wherein the angled surface was configured at an angle between 1 degree and 15 degrees with respect to a horizontal plane, the horizontal plane being perpendicular to a longitudinal direction of the fuselage portion. 40. The power module of embodiment 38, wherein the bonding pad further comprises the opening defined in the central region of the bonding pad before being ultrasonically welded to the support member. 41. The power module of embodiment 40, wherein the opening has a maximum depth between 10 µm and 1000 µm. 42. The power module of embodiment 40, wherein the opening extends the entire length of the body portion of the conductive pin. 43. The power module of embodiment 40, wherein the opening is a conical opening. 44. The power module of embodiment 40, wherein the opening is a curved opening. 45. The power module of embodiment 40, wherein the opening is a cylindrical opening. 46. ​​The power module of embodiment 27, wherein the bonding pad includes the opening defined in the central region of the bonding pad before being ultrasonically welded to the support member. 47. The power module of embodiment 46, wherein the opening was a conical opening. 48. The power module of embodiment 46, wherein the opening is a curved opening. 49. The power module of embodiment 48, wherein the curved opening defines a radius of curvature between 2 mm and 100 mm. 50. The power module of embodiment 46, wherein the opening was a cylindrical opening. 51. The power module of embodiment 46, wherein the opening has a maximum depth between 10 µm and 1000 µm. 52. The power module of embodiment 27, wherein the bonding surface was configured to be ultrasonically welded to a workpiece using torsional vibrations. 53. An ultrasonic welding system configured to weld a conductive pin to a workpiece, the ultrasonic welding system comprising: a sonotrode configured to ultrasonically weld the conductive pin to the workpiece during a welding operation; and a control system configured to control the welding process, wherein the welding process includes bonding a bonding surface of the conductive pin to the workpiece, the bonding surface including at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. 54. The ultrasonic welding system of embodiment 53, wherein the control system is configured to apply process parameters based on the bond area during the welding process. 55. The ultrasonic welding system of embodiment 53, wherein the bonding surface includes the non-planar surface, wherein the control system is configured to apply process parameters based on the non-planar surface during the welding process. 56. The ultrasonic welding system of embodiment 53, wherein the bonding surface has the opening defined in the central region, wherein the control system is configured to apply process parameters during the welding process based on the opening defined in the central region. 57. The ultrasonic welding system of embodiment 53, wherein the bonding surface comprises the non-planar surface and the opening defined in the central region of the non-planar surface, wherein the control system is configured to apply process parameters during the welding process based on the non-planar surface and the opening defined in the central region of the non-planar surface. 58. The ultrasonic welding system of embodiment 53, wherein the process parameters include at least one selection of bond force, bond energy, and bond duration. 59. The ultrasonic welding system according to embodiment 53, wherein the welding process utilizes torsional vibrations applied by the sonotrode. 60. A method for ultrasonically welding a conductive pin to a workpiece, the method comprising the following steps: (a) providing a workpiece; and (b) ultrasonically welding the conductive pin to the workpiece, the conductive pin comprising a body portion and a pin head at one end of the body portion, the pin head defining a bonding surface configured to be ultrasonically welded to the workpiece, the bonding surface comprising at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. 61. The method of embodiment 60, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding based on the bond area. 62. The method of embodiment 60, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding based on the non-planar surface. 63. The method of embodiment 60, wherein step (b) includes applying process parameters using a control system during ultrasonic welding based on the opening defined in the central region. 64. The method of embodiment 60, wherein step (b) includes applying process parameters using a control system during ultrasonic welding based on the non-planar surface and the opening defined in the central region of the non-planar surface. 65. The method of embodiment 60, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding, wherein the process parameters comprise at least one of the following parameters: bond force, bond energy, and bond duration. 66. The method of embodiment 60, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding, wherein the ultrasonic welding uses torsional vibrations applied by a sonotrode configured to ultrasonically weld the conductive pin to the workpiece. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 607,533

[0001] US 10,882,134

[0005] US 11,364,565

[0005] US Patent No. 11,850,676

[0005] US 12.070.814

[0005]

Claims

[1] A conductive pin for ultrasonic welding, the conductive pin comprising: a fuselage section; and a pin head at one end of the body portion, the pin head defining a bonding surface configured to be ultrasonically welded to a workpiece, the bonding surface comprising at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. [2] The conductive pin of claim 1, wherein the bonding surface comprises the non-planar surface. [3] The conductive pin of claim 2, wherein the non-planar surface is a curved surface. [4] The conductive pin according to claim 3, wherein the curved surface has a radius of curvature between 2 mm and 100 mm. [5] The conductive pin according to claim 3, wherein the bonding surface further includes the opening defined in the central region of the bonding surface. [6] The conductive pin of claim 5, wherein the opening has a maximum depth between 10 µm and 1000 µm. [7] The conductive pin according to claim 5, wherein the opening extends over an entire length of the body portion of the conductive pin. [8] The conductive pin of claim 5, wherein the opening is a conical opening. [9] The conductive pin of claim 5, wherein the opening is a curved opening. [10] The conductive pin of claim 9, wherein the curved opening has a radius of curvature between 2 mm and 100 mm. [11] The conductive pin according to claim 5, wherein the opening is a cylindrical opening. [12] The conductive pin of claim 2, wherein the non-planar surface is an angled surface. [13] The conductive pin of claim 12, wherein the angled surface is configured at an angle between 1 degree and 15 degrees with respect to a horizontal plane, the horizontal plane being perpendicular to a longitudinal direction of the body portion. [14] The conductive pin of claim 12, wherein the bonding surface further comprises the opening defined in the central region of the bonding surface. [15] The conductive pin of claim 14, wherein the opening has a maximum depth between 10 µm and 1000 µm. [16] The conductive pin of claim 14, wherein the opening extends over an entire length of the body portion of the conductive pin. [17] The conductive pin of claim 14, wherein the opening is a conical opening. [18] The conductive pin of claim 14, wherein the opening is a curved opening. [19] The conductive pin of claim 14, wherein the opening is a cylindrical opening. [20] The conductive pin of claim 1, wherein the bonding surface includes the opening defined in the central region of the bonding surface. [21] The conductive pin of claim 20, wherein the opening is a conical opening. [22] The conductive pin of claim 20, wherein the opening is a curved opening. [23] The conductive pin of claim 22, wherein the curved opening has a radius of curvature between 2 mm and 100 mm. [24] The conductive pin of claim 20, wherein the opening is a cylindrical opening. [25] The conductive pin of claim 20, wherein the opening has a maximum depth between 10 µm and 1000 µm. [26] The conductive pin of claim 1, wherein the bonding surface is configured to be ultrasonically welded to a workpiece using torsional vibrations. [27] A power module comprising: a semiconductor element; a support member for supporting the semiconductor element; and at least one conductive pin ultrasonically welded to the support member, the conductive pin having a body portion and a pin head at one end of the body portion, the pin head defining a bonding surface welded to the support member, wherein the bonding surface of the conductive pin, prior to ultrasonically welding to the support member, comprised at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. [28] An ultrasonic welding system configured to weld a conductive pin to a workpiece, the ultrasonic welding system comprising a sonotrode configured to ultrasonically weld the conductive pin to the workpiece during a welding operation; and a control system configured to control the welding process, wherein the welding process includes bonding a bonding surface of the conductive pin to the workpiece, the bonding surface including at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. [29] The ultrasonic welding system of claim 28, wherein the control system is configured to apply process parameters based on the bond area during the welding process. [30] The ultrasonic welding system of claim 28, wherein the bonding surface comprises the non-planar surface, wherein the control system is configured to apply process parameters based on the non-planar surface during the welding process. [31] The ultrasonic welding system of claim 28, wherein the bonding surface has the opening defined in the central region, wherein the control system is configured to apply process parameters during the welding process based on the opening defined in the central region. [32] The ultrasonic welding system of claim 28, wherein the bonding surface comprises the non-planar surface and the opening defined in the central region of the non-planar surface, wherein the control system is configured to apply process parameters during the welding process based on the non-planar surface and the opening defined in the central region of the non-planar surface. [33] The ultrasonic welding system of claim 28, wherein the process parameters comprise at least one selection of bond force, bond energy, and bond duration. [34] The ultrasonic welding system of claim 28, wherein the welding process utilizes a torsional vibration applied by the sonotrode. [35] A method for ultrasonically welding a conductive pin to a workpiece, the method comprising the following steps: (a) providing a workpiece; and (b) ultrasonically welding the conductive pin to the workpiece, the conductive pin having a body portion and a pin head at one end of the body portion, the pin head defining a bonding surface configured to be ultrasonically welded to the workpiece, the bonding surface comprising at least one selection of (i) a non-planar surface and (ii) an opening defined in a central region of the bonding surface. [36] The method of claim 35, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding based on the bond area. [37] The method of claim 35, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding based on the non-planar surface. [38] The method of claim 35, wherein step (b) includes applying process parameters using a control system during ultrasonic welding based on the opening defined in the central region. [39] The method of claim 35, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding based on the non-planar surface and the opening defined in the central region of the non-planar surface. [40] The method of claim 35, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding, the process parameters comprising at least one selection of bond force, bond energy, and bond duration. [41] The method of claim 35, wherein step (b) comprises applying process parameters using a control system during ultrasonic welding, wherein the ultrasonic welding uses torsional vibrations applied by a horn configured to ultrasonically weld the conductive pin to the workpiece.

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