Ultrasonic welding systems, sonotrodes and conductive pins for such systems, as well as related workpieces

Abstract

Ultrasonic welding system, comprehensive: a welding head assembly with an ultrasonic transducer; and a sonotrode configured to be carried by the welding head assembly, the sonotrode comprising a functional end configured to weld a conductive pin to a workpiece using ultrasound, the functional end defining a conical opening configured to receive the conductive pin.

Description

REFERENCE TO THE APPLICATION TAKEN IN REFERENCE

[0001] This application claims the legal benefit of preliminary US application No. 63 / 460,088, filed on April 18, 2023, the contents of which are hereby incorporated by reference. AREA

[0002] The invention relates to ultrasonic welding, in particular improved systems for carrying out ultrasonic welding processes, including the welding of conductive pins. BACKGROUND

[0003] Ultrasonic welding is a technology used to join conductive components. In ultrasonic welding, an ultrasonic transducer (e.g., with a sonotrode) can be used to convert electrical energy into mechanical motion / friction (e.g., linear motion / friction, torsional motion / friction, etc.). U.S. Patent No. 10,882,134 (titled "Ultrasonic Welding Systems and Methods for Their Use"), granted to Kulicke and Soffa Industries, Inc., relates to improvements in ultrasonic welding technology and is incorporated herein by reference in its entirety.

[0004] One specific application of ultrasonic welding technology involves the ultrasonic welding of pins (such pins are typically soldered and / or pressed into power modules). U.S. Patent No. 11,850,676 (titled "Ultrasonic Welding Systems, Methods of Their Use and Associated Workpieces Including Welded Conductive Pins"), granted to Kulicke and Soffa Industries, Inc., relates to improvements in ultrasonic welding technology with respect to conductive pins and is also incorporated in its entirety by reference.

[0005] Therefore, it would be desirable to improve ultrasonic welding technology, including in the sense that it relates to the ultrasonic welding of pins. SUMMARY

[0006] According to an exemplary embodiment of the invention, an ultrasonic welding system is provided. The ultrasonic welding system comprises a welding head assembly with an ultrasonic transducer. The ultrasonic welding system also comprises a sonotrode configured to be supported by the welding head assembly, the sonotrode comprising a functional end configured to ultrasonically weld a conductive pin to a workpiece, the functional end defining a conical opening configured to receive the conductive pin.

[0007] According to other embodiments of the invention, the ultrasonic welding system described in the immediately preceding paragraph can have one or more of the following features: The conical opening borders a vacuum channel defined by the sonotrode; the conductive pin comprises a solid shaft section extending from a base section; the conductive pin comprises a conical section between the base section and the shaft section, the conical section being configured to make contact with the functional end at the conical opening during an ultrasonic welding process; the conductive pin defines a through-hole extending along its length; the conductive pin is a rivet; the conical opening is arranged at an angle to the horizontal axis of the ultrasonic welding system (e.g.,the angle lies in a range between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees and / or between 30 and 60 degrees; the width W1 of the conical opening lies between 0.1·W2 and 0.9·W2, 0.2·W2 to 0.8·W2 and / or 0.3·W2 to 0.7·W2 (compared to a width W2 of the end section of the sonotrode); a radial contact length L1 of the conical opening is between 0.2 mm and 5 mm, 0.35 mm and 2 mm and / or 0.5 and 1.5 mm; and / or a surface of the functional end that defines the opening has one or more friction features.

[0008] According to another exemplary embodiment of the invention, a sonotrode is provided for ultrasonic welding. The sonotrode comprises a body section, wherein the body section includes a functional end configured for ultrasonic welding of a conductive pin to a workpiece. The functional end defines a conical opening configured to receive the conductive pin.

[0009] According to other embodiments of the invention, the sonotrode described in the immediately preceding paragraph can have one or more of the following features: the conical opening borders a vacuum channel defined by the sonotrode; the conductive pin comprises a solid shaft section extending from a base section; the conductive pin comprises a conical section between the base section and the shaft section, the conical section being configured to make contact with the functional end at the conical opening during an ultrasonic welding process; the conductive pin defines a through-hole extending along its length; the conductive pin is a rivet; the conical opening is arranged at an angle to the horizontal axis of the ultrasonic welding system (e.g.,the angle lies in a range between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees and / or between 30 and 60 degrees; a width W1 of the conical opening lies between 0.1·W2 and 0.9·W2, 0.2·W2 and 0.8·W2 and / or 0.3·W2 and 0.7·W2 (compared to a width W2 of the end section of the sonotrode); a radial contact length L1 of the conical opening is between 0.2 mm and 5 mm, 0.35 mm and 2 mm and / or 0.5 and 1.5 mm; and / or a surface of the functional end that defines the opening has one or more friction features.

[0010] According to another exemplary embodiment of the invention, a conductive pin configured for ultrasonic welding is provided. The conductive pin comprises (a) a base section configured to be ultrasonically welded to the workpiece, (b) a conical section extending from the base section, and (c) a shaft section extending from the conical section.

[0011] According to other embodiments of the invention, the conductive pin described in the immediately preceding paragraph can have one or more of the following features: The shaft section is a solid conductive shaft; the conical section is configured such that, during an ultrasonic welding process, it comes into contact with a functional end of the sonotrode at a conical opening of the sonotrode; the conductive pin defines a through-hole extending along its length; the conductive pin is a rivet; the conical section is configured at an angle to a horizontal axis extending along the base section (e.g.,the angle lies in a range between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees and / or between 30 and 60 degrees; the width W1 of the conical opening lies between 0.1·W2 and 0.9·W2, 0.2·W2 and 0.8·W2 and / or 0.3·W2 and 0.7·W2 (compared to the width W2 of the end section of the sonotrode); and / or a radial contact length L1 of the conical opening is between 0.2 mm and 5 mm, 0.35 mm and 2 mm and / or 0.5 and 1.5 mm.

[0012] According to a further exemplary embodiment of the invention, a workpiece is provided. The workpiece comprises: a substrate; and a conductive pin which is ultrasonically welded to the substrate. The conductive pin comprises (i) a base section configured to be ultrasonically welded to the substrate, (ii) a conical section extending from the base section, and (iii) a shaft section extending from the conical section.

[0013] According to other embodiments of the invention, the workpiece described in the immediately preceding paragraph may have one or more of the following features: the shaft section is a solid conductive shaft; the conductive pin defines a through-hole extending along its length; the conductive pin is a rivet; the conical section is configured at an angle to a horizontal axis extending along the base section (e.g., the angle is in a range between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees, and / or between 30 and 60 degrees); the width W1 of the conical opening is between 0.1·W2 and 0.9·W2, 0.2·W2 and 0.8·W2, and / or 0.3·W2 and 0.7·W2 (compared to the width W2 of the end section of the sonotrode); and / or a radial contact length L1 of the conical opening is between 0.2 mm and 5 mm, 0.35 mm and 2 mm and / or 0.5 and 1.5 mm.

[0014] An unclaimed method for operating an ultrasonic welding system comprises the following steps: (a) holding a workpiece on a support structure of the ultrasonic welding system (see, for example, workpiece 102a2, support structure 106 and / or ultrasonic welding system 100 in Fig. 1A); and (b) welding a conductive pin from a supply of conductive pins of the ultrasonic welding system to the workpiece using a sonotrode of a welding head assembly of the ultrasonic welding system (see, for example, the one in Fig. 3 welding shown). The conductive pin comprises (i) a base section configured to be welded to the substrate by means of ultrasound, (ii) a conical section extending from the base section, and (iii) a shaft section extending from the conical section.

[0015] According to other embodiments of the invention, the unclaimed method described in the immediately preceding paragraph may have one or more of the following features: The sonotrode comprises a functional end configured to ultrasonically weld the conductive pin to the workpiece, the functional end defining a conical opening configured to receive the conductive pin; the conical opening borders a vacuum channel defined by the sonotrode; the conical section is configured to contact the functional end at the conical opening during step (b); the conductive pin comprises a solid shaft section extending from a base section; the conductive pin defines a through-hole extending along its length; the conductive pin is a rivet;The conical opening is arranged at an angle to a horizontal axis of the ultrasonic welding system (e.g., the angle is in a range between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees, and / or between 30 and 60 degrees); a width W1 of the conical opening is between 0.1·W2 and 0.9·W2, 0.2·W2 and 0.8·W2, and / or 0.3·W2 and 0.7·W2 (compared to a width W2 of the end section of the sonotrode); a radial contact length L1 of the conical opening is between 0.2 mm and 5 mm, 0.35 mm and 2 mm, and / or 0.5 and 1.5 mm; and / or a surface of the functional end defining the opening has one or more frictional features. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention is best understood with reference to the following detailed description 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 have been arbitrarily enlarged or reduced for clarity. The drawings include the following illustrations: Fig. Figure 1A is a block diagram side view of an ultrasonic welding system according to an exemplary embodiment of the invention; Fig. Figure 1B is a block diagram side view of a part of a sonotrode according to a further exemplary embodiment of the invention; Fig. Figures 2A-2E are side views of conductive pins according to various exemplary embodiments of the invention; Fig. 2F is a bottom view of a conductive pin according to certain exemplary embodiments of the invention; and Fig. Figure 3 is a side view of part of a sonotrode for ultrasonically welded connection of a conductive pin to a workpiece according to an exemplary embodiment of the invention. DETAILED DESCRIPTION

[0017] In contrast to conventional ultrasonic welding of pins (using flat-head pins), exemplary aspects of the invention relate to the use of "beveled" conductive pins. Such a beveled pin may, for example, have a conical section extending from a base section. Ultrasonic welding of pins offers several potential advantages, such as (i) improved friction between a conductive pin and a sonotrode tip, (ii) reduced and downward-pointing hairs that cannot grow as long as with flat-head pins, and (iii) improved neck strength. The sonotrode can be adapted to the pin shape for both torsion and linear pin welding.

[0018] Fig. Figure 1A shows an ultrasonic welding system 100. The ultrasonic welding system 100 comprises a welding head assembly 112. The welding head assembly 112 includes an ultrasonic transducer 112b, which carries a sonotrode 202, and is movable along a plurality of essentially horizontal axes. In the Fig. In the example shown, 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 Fig. In the example shown, the welding head assembly 112 is also configured to move along the z-axis of the ultrasonic welding system 100 and about a theta-axis (diameter axis) of the ultrasonic welding system 100. Not all of these axes of movement are required in every application. Using the axes of movement of the welding head assembly 112, the sonotrode 202 can be moved into the correct welding positions relative to a clamped workpiece 102a2.

[0019] Fig. Figure 1A shows a variety of workpieces 102a1, which may include power modules, components of power modules, conductor frames, battery modules, etc. The workpieces 102a1 are provided (by any transport device, which may be included in a material handling system 104, such as a gripper device). The material handling system 104 moves the workpiece 102a1 (e.g., using a conveyor, a gripper device, etc.) to a support structure 106 (e.g., of the material handling system 104). The support structure 106 supports the workpiece (now referred to as the clamped workpiece 102a2 when it is clamped to the support structure 106 by a workpiece clamp) during a welding operation. After the welding process (in which one or more conductive pins 200a were ultrasonically welded to the workpiece), the now welded workpiece 102a3 (e.g.(using a conveying device, a gripping device, etc.) away from the support structure 106.

[0020] The ultrasonic welding system 100 also includes a camera 114 (where the camera 114 can optionally be carried by the welding head assembly 112 or by another part of the ultrasonic welding system 100) for imaging operations relating to the alignment between the sonotrode 202 and the clamped workpiece 102a2, the alignment of the components of the clamped workpiece 102a2, the optical inspection of the weld seams after the welding process, etc.

[0021] The ultrasonic welding system 100 (or other systems within the scope of the invention) can be used to weld various types of workpieces. Exemplary workpieces include a power module, a ladder frame, and / or a battery module.

[0022] According to the invention, various types of ultrasonic movements can be applied to a conductor (e.g., a conductive pin). For example, the sonotrode can be configured to weld a conductor to a workpiece using at least one linear ultrasonic movement and / or one torsional ultrasonic movement.

[0023] Certain of these workpieces are configured to accommodate a conductive pin. As used here, the term "conductive pin" is a conductive structure configured and / or intended to be welded to a workpiece. The conductive pin may have a free end (after welding to a workpiece), and a body section 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 other shape. The term "conductive pin" also includes conductive receptacles or sleeves (e.g., in a tubular form) where the conductive receptacle / sleeve is ultrasonically welded to a workpiece and configured to accommodate another conductive element.According to certain exemplary embodiments of the invention, the ultrasonic welding system 100 comprises a supply 200 of conductive pins configured to provide a plurality of conductive pins for welding using a sonotrode 202. Exemplary configurations for the supply of conductive pins include: a grid arrangement (including columns and rows of conductive pins oriented for easy pickup), a tray conveyor, a hopper, a reel, etc. Alternative configurations are conceivable. The supply 200 of conductive pins can be configured to operate with a buffer system such that the pins are guided through a staging area and are ready for pickup for welding.

[0024] Fig. Figure 1B is a detailed view of a functional end 202a of the sonotrode 202. The functional end 202a is configured to ultrasonically weld a conductive pin to a workpiece. The functional end 202a defines a conical opening 202b, which is configured to accommodate a conductive pin. The conical opening 202b is adjacent to a vacuum channel 202c defined by the sonotrode 202. The conical opening 202b is arranged at an angle Ø with respect to a horizontal axis of the ultrasonic welding system. Exemplary ranges for the angle Ø are between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees, and between 30 and 60 degrees. Of course, other ranges for the angle Ø are also conceivable.

[0025] According to certain exemplary aspects of the invention, a width of the conical opening 202b (W1, in Fig. 1B marked) compared to the total width of the functional end 202a of the sonotrode 202 (W2, in Fig. (marked 1B) significant. Exemplary ranges for W1 are: 0.1·W2 to 0.9·W2; 0.2·W2 to 0.8·W2; and 0.3·W2 to 0.7·W2. Other ratios are conceivable.

[0026] Furthermore, according to certain exemplary aspects of the invention, a radial contact length defining the conical opening 202b (L1, in Fig. 1B), is important because it provides a surface that engages with a corresponding conical section of a conductive pin (see, for example, the conical section 202a1b, which engages with surface 202d in Fig. 3 (in contact). Exemplary ranges for the radial contact length L1 are: 0.2 mm to 5 mm; 0.35 mm to 2 mm; and 0.5 to 1.5 mm. Other radial contact lengths are conceivable.

[0027] The Fig. Figures 2A-2F show a variety of conductive pins (e.g., "beveled" conductive pins) according to various exemplary embodiments of the invention. With reference to the Fig. 2A-2D comprises each individual conductive pin 202a1, 202a2, 202a3, and 202a4, comprising a respective base section (i.e., 202a1a, 202a2a, 202a3a, and 202a4a), a respective conical section (i.e., 202a1b, 202a2b, 202a3b, and 202a4b), and a respective shaft section (i.e., 202a1c, 202a2c, 202a3c, and 202a4c). The respective conical sections are configured at angles (Ø1, Ø2, Ø3, and Ø4) with respect to a horizontal axis extending along the respective base section. Exemplary ranges for each of the angles Ø1, Ø2, Ø3 and Ø4 lie between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees and between 30 and 60 degrees.

[0028] Fig. 2E is a side view in cross-section of a conductive pin 202a5 and Fig. Figure 2F is a bottom-side view of a conductive pin 202a5. The conductive pin 202a5 defines a through-hole 202a5d that extends along its length. The conductive pin 202a5 can, for example, be a conductive rivet. The conductive pin 202a5 comprises a base section 202a5a, a conical section 202a5b, and a shank section 202a5c. The conical section 202a5b is configured at an angle Ø5 with respect to a horizontal axis extending along the base section 202a5a. Example ranges for the angle Ø5 are between 5 and 70 degrees, between 10 and 50 degrees, between 20 and 40 degrees, and between 30 and 60 degrees.

[0029] Fig. Figure 3 shows a functional end 202a of the sonotrode 202 (from Fig. 1B), which during a welding process with a conductive pin 202a1 (from Fig. 2A) is engaged to connect the conductive pin 202a1 to the workpiece 102a2 (or another workpiece, such as the workpiece 102a1 and / or the welded workpiece 102a3) Fig. 1A) to join using ultrasonically welded welding. As in Fig. As shown in Figure 3, the conical section 202a1b of the conductive pin 202a1 touches the functional end of the sonotrode 202 at the conical opening (e.g., the conical opening 202b). Fig. 1B) The surface 202d of the functional end 202a, which defines the opening, may (or may not) have one or more friction features. Examples of such friction features may include: protrusions, pointed structures, a roughened surface, a recessed structure, a patterned surface, a surface with a multitude of depressions or grooves, and / or other features to increase the friction between the functional end and the conductive pin. The term “friction features” is intended to be broad and encompass any feature that produces the desired friction between the functional end of the sonotrode and the conductive pin in connection with a welding process (e.g., ultrasonic welding of pins, etc.).

[0030] As in Fig.As shown in 3, the geometry of the sonotrode (and the conductive pin) leads to an increased total force (where the total force Ft, for example, consists of components of a normal force F and a clamping force F). c (includes). Further advantages may include one or more of the following features: increased friction; reduced lateral slippage; reduced hairs (e.g., reduced overall hair length, reduced occurrence of hairs, etc.); reduced tool wear; reduced power requirement; and / or improved weld quality.

[0031] Although the invention has been largely illustrated and described in relation to a sonotrode defining a cone-shaped opening and conductive pins with a corresponding cone-shaped section, the invention is not limited thereto. For example, other shapes can be used, such as a chamfered shape, a pyramidal shape, etc.

[0032] Although the invention is illustrated and described here with reference to certain embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications to the details can be made within the scope and range of the equivalents of the claims without departing from the invention. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] US 63 / 460,088

[0001] US 10,882,134

[0003] US 11,850,676

[0004]

Claims

[1] Ultrasonic welding system, comprising: a welding head assembly with an ultrasonic transducer; and a sonotrode configured to be carried by the welding head assembly, the sonotrode comprising a functional end configured to weld a conductive pin to a workpiece using ultrasound, the functional end defining a conical opening configured to receive the conductive pin. [2] The ultrasonic welding system according to claim 1, wherein the conical opening borders a vacuum channel defined by the sonotrode. [3] The ultrasonic welding system according to claim 1, wherein the conductive pin comprises a solid shaft section extending from a base section. [4] Ultrasonic welding system according to claim 3, wherein the conductive pin comprises a conical section between the base section and the shaft section, wherein the conical section is configured to come into contact with the functional end at the conical opening during an ultrasonic welding process. [5] Ultrasonic welding system according to claim 1, wherein the conductive pin defines a through-hole extending along its length. [6] Ultrasonic welding system according to claim 1, wherein the conductive pin is a rivet. [7] Ultrasonic welding system according to claim 1, wherein the conical opening is arranged at an angle to the horizontal axis of the ultrasonic welding system, the angle being between 20 and 40 degrees. [8] Ultrasonic welding system according to claim 1, wherein a surface of the functional end defining the opening has one or more friction features. [9] Sonotrode configured for ultrasonic welding, the sonotrode comprising: a body section, wherein the body section includes a functional end configured for ultrasonic welding of a conductive pin to a workpiece, the functional end defining a conical opening configured to receive the conductive pin. [10] Sonotrode according to claim 9, wherein the conical opening is adjacent to a vacuum channel defined by the sonotrode. [11] The sonotrode according to claim 9, wherein the conductive pin comprises a solid shaft section extending from a base section. [12] The sonotrode according to claim 11, wherein the conductive pin comprises a conical section between the base section and the shaft section, wherein the conical section is configured to contact the functional end at the conical opening during an ultrasonic welding process. [13] Sonotrode according to claim 9, wherein the conductive pin defines a through-hole extending along its length. [14] Sonotrode according to claim 9, wherein the conductive pin is a rivet. [15] Sonotrode according to claim 9, wherein the conical opening is arranged at an angle to the horizontal axis of the ultrasonic welding system, the angle being between 20 and 40 degrees. [16] Sonotrode according to claim 9, wherein a surface of the functional end defining the opening has one or more friction features. [17] Conductive pin designed to be ultrasonically welded to a workpiece, the conductive pin comprising: a base section designed to be welded to the workpiece using ultrasound; a cone-shaped section extending from the base section; and a shaft section extending from the conical section. [18] The conductive pen according to claim 17, wherein the shaft section is a solid conductive shaft. [19] The conductive pin according to claim 17, wherein the conical section is configured to come into contact with a functional end of a sonotrode at a conical opening of the sonotrode during an ultrasonic welding process. [20] The conductive pin according to claim 17, wherein the conductive pin defines a through-hole extending along its length. [21] The conductive pin according to claim 17, wherein the conductive pin is a rivet. [22] The conductive pin according to claim 17, wherein the conical section is formed at an angle to a horizontal axis extending along the base section, the angle being between 20 and 40 degrees. [23] Workpiece comprising: a substrate; and a conductive pin which is ultrasonically welded to the substrate, the conductive pin comprising: (i) a base section which is designed to be ultrasonically welded to the substrate, (ii) a conical section extending from the base section, and (iii) a shaft section extending from the conical section. [24] The workpiece according to claim 23, wherein the shaft section is a solid conductive shaft. [25] The workpiece according to claim 23, wherein the conductive pin defines a through hole extending along its length. [26] The workpiece according to claim 23, wherein the conductive pin is a rivet. [27] Workpiece according to claim 23, wherein the conical section is formed at an angle to a horizontal axis extending along the base section, the angle being between 20 and 40 degrees.

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