Ultrasonic welding system, ultrasonic horn for use in such system, electrically conductive pin and workpiece

Abstract

An ultrasonic welding system is provided. The ultrasonic welding system includes a horn assembly including an ultrasonic transducer. The ultrasonic welding system also includes an ultrasonic welding tip configured to be carried by the horn assembly, the ultrasonic welding tip including a working end configured to ultrasonically weld a conductive pin to a workpiece, the working end defining a tapered bore configured to receive the conductive pin.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 460,088, filed April 18, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to ultrasonic welding, and more particularly to an improved system and method for performing ultrasonic welding operations including the soldering of conductive leads. Background Technology

[0004] Ultrasonic welding is a technique used to join conductive components. Ultrasonic welding can use an ultrasonic transducer (e.g., a welding electrode) to convert electrical energy into mechanical motion / scrubbing (e.g., linear motion / scrubbing, torsional motion / scrubbing, etc.). U.S. Patent No. 10,882,134, assigned to Kulicke and Soffa Industries, entitled “ULTRASONIC WELDING SYSTEMS AND METHODS OF USING THE SAME”, relates to improvements in ultrasonic welding technology and is incorporated herein by reference in its entirety.

[0005] Specific applications of ultrasonic welding technology involve ultrasonic pin welding (where such pins are typically soldered and / or press-fitted into power modules). U.S. Patent No. 11,850,676, assigned to Kulicke and Soffa Industries (titled "ULTRASONIC WELDING SYSTEMS, METHODS OF USING THE SAME, AND RELATEDWORKPIECES INCLUDING WELDED CONDUCTIVE PINS") relates to improvements in ultrasonic welding technology associated with conductive pins, and is also incorporated herein by reference in its entirety.

[0006] Therefore, it is desirable to provide an ultrasonic welding system that includes improvements related to ultrasonic pin welding. Utility Model Content

[0007] According to an exemplary embodiment of the present invention, an ultrasonic welding system is provided. The ultrasonic welding system includes a welding head assembly, the welding head assembly including an ultrasonic transducer. The ultrasonic welding system also includes an ultrasonic welding electrode configured to be carried by the welding head assembly, the ultrasonic welding electrode including a working end configured to ultrasonically weld conductive leads to a workpiece, the working end defining a tapered orifice configured to receive the conductive leads.

[0008] According to other embodiments of the present invention, the ultrasonic welding system described in the preceding paragraph may have any one or more of the following features: a tapered bore adjacent to a vacuum channel defined by an ultrasonic welding electrode; the conductive pin comprising a solid shaft portion extending from a base portion; the conductive pin comprising a tapered portion between the base portion and the shaft portion, the tapered portion being configured to contact the working end at the tapered bore during ultrasonic welding operation; the conductive pin defining a through hole extending along its length; the conductive pin being a riveting member; the tapered bore being configured at an angle relative to the horizontal axis of the ultrasonic welding system. For example, the angle is in the range of 5-70 degrees, 10-50 degrees, 20-40 degrees and / or 30-60 degrees; the width W1 of the tapered hole is between 0.1*W2 and 0.9*W2, between 0.2*W2 and 0.8*W2 and / or between 0.3*W2 and 0.7*W2 (compared to the width W2 of the end of the ultrasonic welding electrode); the radial contact length L1 of the tapered hole is between 0.2 mm and 5 mm, between 0.35 mm and 2 mm, and / or between 0.5 and 1.5 mm; and / or the surface of the defining hole of the working end includes one or more friction features.

[0009] According to another exemplary embodiment of the present invention, an ultrasonic welding electrode for ultrasonic welding is provided. The ultrasonic welding electrode includes a body portion including a working end configured to ultrasonically weld conductive leads to a workpiece. The working end defines a tapered aperture configured to receive the conductive leads.

[0010] According to other embodiments of the present invention, the ultrasonic welding electrode described in the preceding paragraph may have any one or more of the following features: a tapered bore adjacent to a vacuum channel defined by the ultrasonic welding electrode; the conductive pin including a solid shaft portion extending from the base portion; the conductive pin including a tapered portion between the base portion and the shaft portion, the tapered portion being configured to contact the working end at the tapered bore during ultrasonic welding operation; the conductive pin defining a through hole extending along its length; the conductive pin being a riveted member; the tapered bore being configured at an angle relative to the horizontal axis of the ultrasonic welding system (e.g., ...). For example, the angle is in the range of 5-70 degrees, 10-50 degrees, 20-40 degrees and / or 30-60 degrees; the width W1 of the tapered hole is between 0.1*W2 and 0.9*W2, between 0.2*W2 and 0.8*W2 and / or between 0.3*W2 and 0.7*W2 (compared to the width W2 of the end of the ultrasonic welding electrode); the radial contact length L1 of the tapered hole is between 0.2 mm and 5 mm, between 0.35 mm and 2 mm, and / or between 0.5 and 1.5 mm; and / or the surface of the defining hole of the working end includes one or more friction features.

[0011] According to another exemplary embodiment of the present invention, a conductive pin configured for ultrasonic welding is provided. The conductive pin includes (a) a base portion configured for ultrasonic welding to a workpiece, (b) a tapered portion extending from the base portion, and (c) a axial portion extending from the tapered portion.

[0012] According to other embodiments of the present invention, the conductive pin described in the preceding paragraph may have any one or more of the following features: the shaft portion is a solid conductive shaft; the tapered portion is configured to contact the working end of the ultrasonic welding electrode at the tapered hole of the ultrasonic welding electrode during ultrasonic welding operation; the conductive pin defines a through hole extending along its length; the conductive pin is a riveted member; the tapered portion is configured at an angle relative to a horizontal axis extending along the base portion (e.g., the angle is between 5 and 70 degrees). The taper hole is within the range of 10-50 degrees, 20-40 degrees and / or 30-60 degrees; the width W1 of the taper hole is between 0.1*W2 and 0.9*W2, between 0.2*W2 and 0.8*W2 and / or between 0.3*W2 and 0.7*W2 (compared to the width W2 of the end of the ultrasonic welding electrode); and / or the radial contact length L1 of the taper hole is between 0.2mm and 5mm, between 0.35mm and 2mm, and / or between 0.5mm and 1.5mm.

[0013] According to another exemplary embodiment of the present invention, a workpiece is provided. The workpiece includes: a substrate; and conductive pins ultrasonically welded to the substrate. The conductive pins include: (i) a base portion configured for ultrasonic welding to the substrate; (ii) a tapered portion extending from the base portion; and (iii) a shaft portion extending from the tapered portion.

[0014] According to other embodiments of the present invention, the workpiece described in the preceding paragraph may have any one or more of the following features: the shaft portion is a solid conductive shaft; the conductive pin defines a through hole extending along its length; the conductive pin is a riveting member; the tapered portion is configured at an angle relative to a horizontal axis extending along the base portion (e.g., the angle is in the range of 5-70 degrees, 10-50 degrees, 20-40 degrees, and / or 30-60 degrees); the width W1 of the tapered hole is between 0.1*W2 and 0.9*W2, between 0.2*W2 and 0.8*W2, and / or between 0.3*W2 and 0.7*W2 (compared to the width W2 of the end of the ultrasonic welding electrode); and / or the radial contact length L1 of the tapered hole is between 0.2 mm and 5 mm, between 0.35 mm and 2 mm, and / or between 0.5 mm and 1.5 mm.

[0015] According to another exemplary embodiment of the present invention, a method for operating an ultrasonic welding system is provided. The method includes the following steps: (a) supporting a workpiece on a support structure of the ultrasonic welding system (e.g., see...). Figure 1A (a) the workpiece 102a2, the support structure 106, and / or the ultrasonic welding system 100; and (b) using the ultrasonic welding electrode of the welding head assembly of the ultrasonic welding system to weld conductive pins from the conductive pin supply of the ultrasonic welding system to the workpiece (e.g., see...). Figure 3 (as shown in the welding diagram). The conductive pin includes: (i) a base portion configured for ultrasonic welding to a substrate; (ii) a tapered portion extending from the base portion; and (iii) a shaft portion extending from the tapered portion.

[0016] According to other embodiments of the present invention, the method described in the preceding paragraph may have any one or more of the following features: the ultrasonic welding electrode includes a working end configured to ultrasonically weld a conductive pin to a workpiece; the working end defines a tapered bore configured to receive the conductive pin; the tapered bore is adjacent to a vacuum channel defined by the ultrasonic welding electrode; the tapered portion is configured to contact the working end at the tapered bore during step (b); the conductive pin includes a solid shaft portion extending from a base portion; the conductive pin defines a through hole extending along its length; the conductive pin is a riveting member; the tapered bore is configured at an angle relative to the horizontal axis of the ultrasonic welding system (e.g., the angle is between 5-70 degrees, 10-50 degrees). The width W1 of the tapered hole is between 0.1*W2 and 0.9*W2, between 0.2*W2 and 0.8*W2, and / or between 0.3*W2 and 0.7*W2 (compared to the width W2 of the end of the ultrasonic welding electrode); the radial contact length L1 of the tapered hole is between 0.2mm and 5mm, between 0.35mm and 2mm, and / or between 0.5mm and 1.5mm; and / or the surface of the defining hole of the working end includes one or more friction features. Attached Figure Description

[0017] The present invention can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, the various features in the drawings are not to scale. Instead, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced. The drawings include the following illustrations:

[0018] Figure 1A This is a block diagram side view of an ultrasonic welding system according to an exemplary embodiment of the present invention;

[0019] Figure 1BThis is a block diagram side view of a portion of an ultrasonic welding electrode according to another exemplary embodiment of the present invention;

[0020] Figures 2A to 2E This is a side view of a conductive pin according to various exemplary embodiments of the present invention;

[0021] Figure 2F This is a bottom view of a conductive pin according to a specific exemplary embodiment of the present invention; and

[0022] Figure 3 This is a side view of a portion of an ultrasonic welding electrode for ultrasonically welding conductive pins to a workpiece, according to an exemplary embodiment of the present invention. Detailed Implementation

[0023] Compared to conventional ultrasonic lead soldering (using flat-tipped leads), exemplary aspects of this invention relate to the use of "beveled" conductive leads. For example, such beveled leads may include a tapered portion extending from a base portion. Ultrasonic lead soldering offers several potential benefits, such as (i) improved friction between the conductive lead and the tip of the ultrasonic soldering electrode, (ii) reduced and downward-growing spinel whiskers that would not grow with flat-tipped leads, and (iii) improved neck strength. The ultrasonic soldering electrode can be matched to lead shapes for both torsional and linear lead soldering.

[0024] Figure 1A An ultrasonic welding system 100 is shown. The ultrasonic welding system 100 includes a welding head assembly 112. The welding head assembly 112 includes an ultrasonic transducer 112b carrying an ultrasonic welding electrode 202 and is movable along a plurality of generally horizontal axes. In the example shown in FIG1, 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 FIG1, the welding head assembly 112 is also configured along the z-axis of the ultrasonic welding system 100 and around the θ-axis of the ultrasonic welding system 100. (Axis) movement. Not all of these axes of motion are required in every application. Using the axes of motion of the welding head assembly 112, the ultrasonic welding electrode 202 can be moved relative to the clamped workpiece 102a2 to the appropriate welding position.

[0025] Figure 1AMultiple workpieces 102a1 are shown, which may include power modules, components of power modules, lead frames, battery modules, etc. Workpieces 102a1 are provided (via any desired transport assembly that may be included in the material handling system 104, such as a clamping assembly). The material handling system 104 moves workpieces 102a1 (e.g., using a conveyor assembly, using a clamping assembly, etc.) to a support structure 106 (e.g., a support structure of the material handling system 104). The support structure 106 supports the workpieces during the welding operation (now labeled as clamping workpiece 102a2 when clamped against the support structure 106 using a workpiece clamp). After the welding operation (in which one or more conductive pins 200a have been ultrasonically welded to the workpiece), the now-welded workpiece 102a3 is moved away from the support structure 106 (e.g., using a conveyor assembly, using a clamping assembly, etc.).

[0026] The ultrasonic welding system 100 also includes a camera 114 (which may optionally be carried by the welding head assembly 112 or by another part of the ultrasonic welding system 100) for imaging operations related to alignment between the ultrasonic welding electrode 202 and the clamped workpiece 102a2, alignment of components of the clamped workpiece 102a2, and optical inspection of the welded portion after the welding operation.

[0027] Various types of workpieces can be welded using the ultrasonic welding system 100 (or other systems within the scope of this invention). Exemplary workpieces include power modules, lead frames, and / or battery modules.

[0028] According to this invention, various types of ultrasonic motion can be applied to a conductor (e.g., a conductive pin). For example, an ultrasonic welding electrode can be configured to weld the conductor to a workpiece using at least one of linear ultrasonic motion and torsional ultrasonic motion.

[0029] Specific workpieces among these are configured to receive conductive pins. As used herein, the term "conductive pin" is a conductive structure configured and / or intended to be welded to a workpiece. A conductive pin may have a free end (after welding to the workpiece), and the body portion of the conductive pin may extend substantially vertically from the "welded" end to the free end. The cross-section of a conductive pin may be circular, square, rectangular, or have any desired cross-section. The term conductive pin should also be interpreted as including conductive sockets or sleeves (e.g., tubular shapes) wherein the conductive socket / sleeve is ultrasonically welded to the workpiece and configured to receive another conductive element. According to a specific exemplary embodiment of the present invention, an ultrasonic welding system 100 includes a conductive pin supplier 200 configured to provide a plurality of conductive pins for welding using an ultrasonic welding electrode 202. Exemplary configurations for the conductive pin supplier include: a grid arrangement (including columns and rows of conductive pins oriented in an easily pickable manner), a bowl feeder, a hopper, a spool, etc. Alternative configurations are contemplated. The conductive pin supply 200 can be configured to operate in conjunction with a buffer system, such that pins are fed through a staging area, ready to be picked up for soldering.

[0030] Figure 1B This is a detailed view of the working end 202a of the ultrasonic welding electrode 202. The working end 202a is configured to ultrasonically weld conductive leads to a workpiece. The working end 202a defines a tapered aperture 202b configured to receive the conductive leads. The tapered aperture 202b is adjacent to a vacuum channel 202c defined by the ultrasonic welding electrode 202. The tapered aperture 202b is configured at an angle relative to the horizontal axis of the ultrasonic welding system. angle Exemplary ranges are between 5-70 degrees, 10-50 degrees, 20-40 degrees, and 30-60 degrees. Of course, angles can be imagined. Other ranges.

[0031] According to a specific exemplary aspect of the present invention, the total width (W2) of the working end 202a of the ultrasonic welding electrode 202 is... Figure 1B Compared to the marked area, the width (W1, in the middle) of the tapered hole 202b Figure 1B The middle marker is 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.

[0032] Furthermore, according to a specific exemplary aspect of the present invention, the radial contact length (L1, in) of the tapered hole 202b is defined. Figure 1B The middle mark () is significant because it provides a corresponding tapered portion for the conductive pin (e.g., see with...). Figure 3The surface 202d contacts the tapered portion 202a1b) of the mating surface. Exemplary ranges for the radial contact length L1 are: 0.2 mm to 5 mm; 0.35 mm to 2 mm; and 0.5 mm to 1.5 mm. Other radial contact lengths are conceivable.

[0033] Figures 2A to 2F A plurality of conductive pins (e.g., "beveled" conductive pins) according to various exemplary embodiments of the present invention are shown. Reference Figures 2A to 2D Each of the conductive pins 202a1, 202a2, 202a3, and 202a4 includes a corresponding base portion (i.e., 202a1a, 202a2a, 202a3a, and 202a4a), a corresponding tapered portion (i.e., 202a1b, 202a2b, 202a3b, and 202a4b), and a corresponding shaft portion (i.e., 202a1c, 202a2c, 202a3c, and 202a4c). The corresponding tapered portion is configured at an angle relative to a horizontal axis extending along the corresponding base portion. and ).angle and The exemplary ranges for each angle are between 5-70 degrees, 10-50 degrees, 20-40 degrees, and 30-60 degrees.

[0034] Figure 2E This is a cross-sectional side view of conductive pin 202a5, and Figure 2F This is a bottom view of the conductive pin 202a5. The conductive pin 202a5 defines a through-hole 202a5d extending along its length. The conductive pin 202a5 can be, for example, a conductive rivet. The conductive pin 202a5 includes a base portion 202a5a, a tapered portion 202a5b, and a shaft portion 202a5c. The tapered portion 202a5b is configured at an angle relative to a horizontal axis extending along the base portion 202a5a. angle Exemplary ranges are between 5-70 degrees, between 10-50 degrees, between 20-40 degrees, and between 30-60 degrees.

[0035] Figure 3 The ultrasonic welding electrode 202 (from) is shown. Figure 1B The working end 202a is used for ultrasonically welding conductive pins 202a1 to workpiece 102a2 (or another workpiece, such as from...). Figure 1A During the welding operation of workpiece 102a1 and / or welding workpiece 102a3, the conductive pin 202a1 (from Figure 2A ) Joining. For example Figure 3 As shown, the tapered portion 202a1b of the conductive pin 202a1 is in the tapered hole (e.g., Figure 1BThe working end of the ultrasonic soldering electrode 202 contacts the tapered hole 202b) of the working end 202a. The surface 202d defining the hole of the working end 202a may (or may not) include one or more friction features. Examples of such friction features may include: protrusions; pointed structures; rough surfaces; recessed structures; patterned surfaces; surfaces including multiple recesses or grooves; and / or other features that increase friction between the working end and the conductive pin. The term "friction feature" is intended to be interpreted broadly as any feature that, in conjunction with a soldering operation (e.g., ultrasonic pin soldering, etc.), generates desired friction between the working end of the ultrasonic soldering electrode and the conductive pin.

[0036] like Figure 3 As shown, the geometry of the ultrasonic welding electrode (and conductive pin) results in an increase in total force (e.g., where the total force F...). t Including the normal force F and the clamping force F c (The component). Additional benefits may include one or more of the following: increased friction; reduced lateral slip; reduced whiskers (e.g., reduced total whisker length, reduced whisker formation, etc.); reduced tool wear; reduced power requirements; and / or improved weld quality.

[0037] Although the present invention has been illustrated and described primarily with respect to the ultrasonic welding electrode defining the tapered hole and the conductive pin including the corresponding tapered portion, the present invention is not limited thereto. For example, other shapes, such as chamfered shapes, pyramid shapes, etc., may be utilized.

[0038] Although this invention has been illustrated and described with reference to specific embodiments, it is not intended to be limited to the details shown. Rather, various modifications may be made to the details within the scope and implications of the equivalents of the claims without departing from the invention.

Claims

1. An ultrasonic welding system, characterized in that, include: Welding head assembly, the welding head assembly including an ultrasonic transducer; as well as An ultrasonic welding electrode, configured to be carried by the welding head assembly, the ultrasonic welding electrode including a working end configured to ultrasonically weld conductive pins to a workpiece, the working end defining a tapered aperture configured to receive the conductive pins.

2. The ultrasonic welding system according to claim 1, characterized in that, The tapered hole is adjacent to the vacuum channel defined by the ultrasonic welding electrode.

3. The ultrasonic welding system according to claim 1, characterized in that, The conductive pin includes a solid shaft portion extending from the base portion.

4. The ultrasonic welding system according to claim 3, characterized in that, The conductive pin includes a tapered portion between the base portion and the shaft portion, the tapered portion being configured to contact the working end at the tapered bore during ultrasonic welding operations.

5. The ultrasonic welding system according to claim 1, characterized in that, The conductive pin defines a through-hole extending along its length.

6. The ultrasonic welding system according to claim 1, characterized in that, The conductive pin is a riveted component.

7. The ultrasonic welding system according to claim 1, characterized in that, The tapered hole is configured at an angle relative to the horizontal axis of the ultrasonic welding system, the angle being between 20 and 40 degrees.

8. The ultrasonic welding system according to claim 1, characterized in that, The surface defining the hole at the working end includes one or more friction features.

9. An ultrasonic welding electrode configured for ultrasonic welding, characterized in that, The ultrasonic welding electrode includes: The body portion includes a working end configured to ultrasonically weld conductive pins to a workpiece, the working end defining a tapered hole configured to receive the conductive pins.

10. The ultrasonic welding electrode according to claim 9, characterized in that, The tapered hole is adjacent to the vacuum channel defined by the ultrasonic welding electrode.

11. The ultrasonic welding electrode according to claim 9, characterized in that, The conductive pin includes a solid shaft portion extending from the base portion.

12. The ultrasonic welding electrode according to claim 11, characterized in that, The conductive pin includes a tapered portion between the base portion and the shaft portion, the tapered portion being configured to contact the working end at the tapered bore during ultrasonic welding operations.

13. The ultrasonic welding electrode according to claim 9, characterized in that, The conductive pin defines a through-hole extending along its length.

14. The ultrasonic welding electrode according to claim 9, characterized in that, The conductive pin is a riveted component.

15. The ultrasonic welding electrode according to claim 9, characterized in that, The tapered hole is configured at an angle relative to the horizontal axis of the ultrasonic welding system, the angle being between 20 and 40 degrees.

16. The ultrasonic welding electrode according to claim 9, characterized in that, The surface defining the hole at the working end includes one or more friction features.

17. A conductive pin configured for ultrasonic welding to a workpiece, characterized in that, The conductive pin includes: A base portion, the base portion being configured to be ultrasonically welded to the workpiece; The tapered portion extending from the base portion; and The shaft portion extending from the tapered portion.

18. The conductive pin according to claim 17, characterized in that, The shaft portion is a solid conductive shaft.

19. The conductive pin according to claim 17, characterized in that, The tapered portion is configured to contact the working end of the ultrasonic welding electrode at the tapered orifice of the ultrasonic welding electrode during ultrasonic welding operations.

20. The conductive pin according to claim 17, characterized in that, The conductive pin defines a through-hole extending along its length.

21. The conductive pin according to claim 17, characterized in that, The conductive pin is a riveted component.

22. The conductive pin according to claim 17, characterized in that, The tapered portion is configured at an angle relative to a horizontal axis extending along the base portion, the angle being between 20 and 40 degrees.

23. A workpiece, characterized in that, include: substrate; as well as A conductive pin, which is ultrasonically welded to the substrate, the conductive pin comprising (i) a base portion configured to be ultrasonically welded to the substrate, (ii) a tapered portion extending from the base portion, and (iii) an axial portion extending from the tapered portion.

24. The workpiece according to claim 23, characterized in that, The shaft portion is a solid conductive shaft.

25. The workpiece according to claim 23, characterized in that, The conductive pin defines a through-hole extending along its length.

26. The workpiece according to claim 23, characterized in that, The conductive pin is a riveted component.

27. The workpiece according to claim 23, characterized in that, The tapered portion is configured at an angle relative to a horizontal axis extending along the base portion, the angle being between 20 and 40 degrees.

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