Patent Description:
Ultrasonic energy is widely used in forming interconnections between two or more materials. For examples, wire bonding machines (e.g., ball bonding machines, wedge bonding machines, ribbon bonding machines, etc.) are used to bond a wire or ribbon to a bonding location. However, wire bonding utilizes relatively low levels of energy (e.g., bond force, ultrasonic energy, etc.). Exemplary wire bonding machines are marketed by Kulicke and Soffa Industries, Inc. of Fort Washington, Pennsylvania.

Certain applications involve joining of materials other than wire. Welding has been considered for such applications. Ultrasonic welding is also a widely used technology. Ultrasonic welding may use an ultrasonic converter (e.g., carrying a sonotrode) for converting electrical energy into mechanical movement/scrub (e.g., linear movement/scrub, torsional movement/scrub, etc.). However, existing ultrasonic welding technology and equipment is limited in its ability to provide solutions that can satisfy market demand in terms of cost, operational efficiency, flexibility, portability, and related factors.

Thus, it would be desirable to improve ultrasonic welding technology to overcome existing barriers to potential markets.

According to a first aspect of the present invention, an ultrasonic welding system is defined in claim <NUM>.

The ultrasonic welding system includes a support structure for supporting a workpiece. The ultrasonic welding system also includes a weld head assembly including an ultrasonic converter carrying a sonotrode. The weld head assembly is moveable along a plurality of substantially horizontal axes. The sonotrode is configured to operate during a welding operation at a bond force of between <NUM>-<NUM>, and with a sonotrode tip motion amplitude of between <NUM>-<NUM> microns.

According to a second aspect of the present invention, method of operating an ultrasonic welding system is defined in claim <NUM>.

The method includes the steps of: (a) supporting a workpiece on a support structure of the ultrasonic welding system; and (b) welding a first portion of the workpiece to a second portion of the workpiece using a weld head assembly including an ultrasonic converter carrying a sonotrode, the weld head assembly being moveable along a plurality of substantially horizontal axes, the sonotrode being configured to weld the first portion of the workpiece to the second portion of the workpiece during a welding operation at a bond force of between <NUM>-<NUM>, and with a sonotrode tip motion amplitude of between <NUM>-<NUM> microns.

The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. Included in the drawings are the following figures:.

In accordance with the invention, ultrasonic welding capability is provided in welding systems (and corresponding methods) that may achieve efficient volume production. Aspects of the invention relate to cameras (e.g., for pattern recognition), process diagnostics, material handling and fixturing / clamping systems, cleaning (debris removal) systems, (optical) inspection systems, amongst others.

<FIG> illustrates an ultrasonic welding system <NUM>. Ultrasonic welding system <NUM> includes an input workpiece supply <NUM> for providing a workpiece 102a1, where input workpiece supply <NUM> is configured to carry a plurality of workpieces 102a1 (e.g., supply <NUM> may be a carrier such as a magazine handler for carrying a plurality of workpieces 102a1, or other supply structure suitable for the application specific workpiece, etc.). Exemplary workpieces 102a1 carried by input workpiece supply <NUM> include power modules, components of power modules, lead frames, battery modules, etc. Workpieces 102a1 are provided (by any desired transport assembly which may be included in a material handling system <NUM>, such as a gripper assembly) from input workpiece supply <NUM> to a material handling system <NUM>. Material handling system <NUM> moves the workpiece 102a1 (e.g., using a conveyor assembly, using a gripper assembly, etc.) from the input workpiece supply <NUM> to the support structure <NUM>. Support structure <NUM> supports the workpiece (now labelled as clamped workpiece 102a2, when clamped against support structure <NUM> using workpiece clamp <NUM>) during a welding operation. After the welding operation (described below with respect to weld head assembly <NUM>), the now welded workpiece 102a3 is moved (e.g., using a conveyor assembly, using a gripper assembly, etc.) from a portion of material handling <NUM> downstream of support structure <NUM>, to an output workpiece supply <NUM>. Output workpiece supply <NUM> is configured to receive workpieces 102a3 after processing by weld head assembly <NUM> (where weld head assembly <NUM> includes an ultrasonic converter 112b carrying a sonotrode 112a). Output workpiece supply <NUM> may be a carrier such as a magazine handler for carrying a plurality of welded workpieces 102a3, or other supply structure suitable for the application specific workpiece.

Ultrasonic welding system <NUM> includes a weld head assembly <NUM>. Weld head assembly includes an ultrasonic converter 112b carrying a sonotrode 112a, and is moveable along a plurality of substantially horizontal axes. In the example shown in <FIG>, weld head assembly <NUM> is configured to move along the x-axis and the y-axis of ultrasonic welding system <NUM> (see example x-axis and y-axis on <FIG>). In the example shown in <FIG>, weld head assembly <NUM> is also configured to move along the z-axis of ultrasonic welding system <NUM>, and about a theta axis (Ø-axis) of ultrasonic welding system <NUM>. Using the motion axes of weld head assembly <NUM>, sonotrode 112a is able to be moved into proper welding positions with respect to clamped workpiece 102a2. Camera <NUM> is also provided (where camera may optionally be carried by weld head assembly <NUM>, or may be carried by another part of ultrasonic welding system <NUM>) for imaging operations related to the alignment between sonotrode 112a and clamped workpiece 102a2, the alignment of the components of clamped workpiece 102a2 in itself, optical inspection of the welds after welding operation, etc..

According to certain exemplary embodiments of the invention, during the welding operations, exemplary technical specifications include: (i) the sonotrode being configured to operate at a bond force of between <NUM>-<NUM>, or the sonotrode being configured to operate at a bond force of between <NUM>-<NUM>, or the sonotrode being configured to operate at a bond force of between <NUM>-<NUM>; (ii) the sonotrode tip motion amplitude being between <NUM>-<NUM> microns, or the sonotrode tip motion amplitude being between <NUM>-<NUM> microns, or the sonotrode tip motion amplitude being between <NUM>-<NUM> microns; (iii) the sonotrode being configured to form an ultrasonic weld between a first portion of a workpiece and a second portion of a workpiece having an area in a range between <NUM>-<NUM><NUM>; or the sonotrode being configured to form an ultrasonic weld between a first portion of a workpiece and a second portion of a workpiece having an area in a range between <NUM>-<NUM><NUM>; or the sonotrode being configured to form an ultrasonic weld between a first portion of a workpiece and a second portion of a workpiece having an area in a range between <NUM>-<NUM><NUM>; and (iv) the sonotrode being configured to operate at a frequency in a range between <NUM>-<NUM>, or the sonotrode being configured to operate at a frequency in a range between <NUM>-<NUM>, or the sonotrode being configured to operate at a frequency in a range between <NUM>-<NUM>. Exemplary thicknesses of the conductive contact of the contact element (the part of the workpiece being contacted by the sonotrode) include: between <NUM>-<NUM>; <NUM>-<NUM>, and <NUM>-<NUM>.

<FIG> is an overhead view of the elements of ultrasonic welding system <NUM> shown in <FIG>.

Various types of workpieces may be welded using ultrasonic welding system <NUM> (or other systems with the scope of the invention). Such workpieces may include a first portion of the workpiece configured to be welded to a second portion of the workpiece. <FIG> illustrate an example of such workpieces - where workpiece <NUM> of <FIG> is an example of workpiece 102a1 in <FIG>. In the example of <FIG>, the first portion of the workpiece <NUM> is a contact element <NUM> including a plurality of conductive contacts 304a (and contact element <NUM> also includes external contacts 304b configured for connection to an external circuit), and the second portion of the workpiece is a base structure <NUM> including a plurality of conductive regions 302a. In the example of <FIG>, contact element <NUM> is already provided on base structure <NUM>. Specifically, conductive contacts 304a are aligned with conductive regions 302a, and are ready for welding.

After positioning workpiece <NUM> on a support structure (e.g., support structure <NUM> of ultrasonic welding system <NUM> in <FIG>), a sonotrode is used to form ultrasonic welds. <FIG> illustrates workpiece <NUM> from <FIG>, but with <NUM> examples of different ultrasonic welds having been formed. A first ultrasonic weld 304a1 is formed between a conductive contact 304a and a respective conductive region 302a, where ultrasonic weld 304a1 is formed using ultrasonic torsional motion (thereby forming a substantially round ultrasonic weld 304a1). Of course, other types of ultrasonic motion (other than torsional motion) are contemplated. For example, <FIG> illustrates a second ultrasonic weld 304a2 (formed using linear ultrasonic motion, for example, along an x-axis), and a third ultrasonic weld 304a3 (formed using linear ultrasonic motion, for example, along a y-axis that is substantially perpendicular to the x-axis). Ultrasonic welds 304a2 and 304a3 can also be formed by torsional ultrasonic motion (e.g., torsional ultrasonic motion may, of course, be used to form non-round ultrasonic welds). The fourth ultrasonic weld 304a4, formed using linear or torsional motion, covers the conductive contact area to three of its edges. Besides linear and torsional ultrasonic motion, combinations of both can be used.

Referring again back to <FIG>, input workpiece supply <NUM> includes workpieces 102a1 including each of a first portion and a second portion, already assembled together, and ready for welding. For example, workpieces 102a1 may be workpiece <NUM> from <FIG> including a first portion (contact element <NUM>) assembled together with a second portion (base structure <NUM>), and ready for welding. However, according to certain embodiments of the invention, the first portion of a workpiece (e.g., a contact element) may not be assembled together with the second portion (e.g., a base structure) at the start of processing by the ultrasonic welding system. <FIG> illustrates such a system.

Referring now to <FIG>, ultrasonic welding system <NUM> includes a contact element supply <NUM> (e.g., a magazine or other supply including a plurality of contact elements <NUM>) and a base structure supply <NUM> (e.g., a magazine or other supply including a plurality of base structures <NUM>). Ultrasonic welding system <NUM> also includes a workpiece assembly station <NUM> for assembling contact elements <NUM> with respective base structures <NUM>. More specifically, a base structure removal tool 452a removes a base structure <NUM> from base structure supply <NUM>, and moves the base structure <NUM> to support structure 454a of workpiece assembly station <NUM>. For example, base structure removal tool 452a may be a gripper type tool configured to move along the x-axis, the y-axis, and a z-axis. Likewise, a contact element removal tool 450a removes a contact element <NUM> from contact element supply <NUM>, and moves the contact element <NUM> to support structure 454a (on top of base structure <NUM>). For example, contact element removal tool 450a may be a gripper type tool configured to move along the x-axis, the y-axis, and a z-axis. Once aligned / assembled, assembly clamp 454b is used to keep contact element <NUM> positioned relative to base structure <NUM>. Camera <NUM> is according to the present invention used to help with and ensure proper alignment of contact element <NUM> to base structure <NUM>. Assembly tool <NUM> may provide further assembly functions (e.g., pressing, adhesive distribution, etc.).

After processing (and assembly) at workpiece assembly station <NUM>, the assembled workpiece <NUM> (now labelled as workpiece 300a1 in <FIG>) is provided to material handling system <NUM> (substantially similar to material handling system <NUM> of <FIG>). The workpiece <NUM> is then moved to support structure <NUM> (substantially similar to support structure <NUM> of <FIG>). Workpiece clamp <NUM> (substantially similar to workpiece clamp <NUM> of <FIG>) secures clamped workpiece 300a2 against support structure <NUM>. Sonotrode 412a (substantially similar to sonotrode 112a of <FIG>) is carried by ultrasonic converter 412b (where converter 412b is included in weld head assembly <NUM>), and ultrasonically welds conductive contacts (of contact element <NUM> of workpiece 300a2) to conductive regions (of base structure <NUM> of workpiece 300a2), using camera <NUM> (substantially similar to camera <NUM> of <FIG>) for alignment. After welding, the now welded workpiece 300a3 is moved to output workpiece supply <NUM> (substantially similar to output workpiece supply <NUM> of <FIG>).

The operation of weld head assembly <NUM> of ultrasonic welding system <NUM> may be substantially similar to that described above with respect to weld head assembly <NUM> of ultrasonic welding system <NUM> of <FIG>. Further, the exemplary technical specifications described herein (e.g., the exemplary ranges for each of operational bond force of the sonotrode, sonotrode tip motion amplitude, ultrasonic weld area, and operational frequency of the sonotrode, conductive contact thicknesses, etc.) are equally applicable to the ultrasonic welding systems of <FIG> and <FIG>, as well as any other ultrasonic welding system within the scope of the invention.

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown.

Claim 1:
An ultrasonic welding system (<NUM>, <NUM>) comprising:
a support structure (<NUM>, <NUM>) for supporting a workpiece (102a1, <NUM>, 300a1);
a weld head assembly (<NUM>, <NUM>) including an ultrasonic converter carrying a sonotrode (112a, 412a), the sonotrode being configured to operate during a welding operation at a bond force of between <NUM>-<NUM>, and with a sonotrode tip motion amplitude of between <NUM>-<NUM> microns;
the system (<NUM>, <NUM>) being characterised by:
the weld head assembly being movable along a plurality of substantially horizontal axes;
a camera (<NUM>, <NUM>), said camera preferably being carried by the weld head assembly, for imaging operations related to the alignment between sonotrode and clamped workpiece.