Method of cutting wire on wire bonding system, and related cutting blade and wire bonding system

Abstract

A wire bonding system is provided herein. The wire welding system comprises a welding tool. The wire bonding system also includes a cutter disposed adjacent to the seaming tool. The cutting knife defines a face on one side of the cutting knife adjacent to a tip portion of the cutting knife. The face is configured to contact the wire prior to a cutting operation.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 461,352, filed April 24, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to wire bonding (including strip bonding) operations, and more specifically to cutting / cleaving knives used in connection with such operations. Background Technology

[0004] In the fabrication and packaging of semiconductor devices, wire bonding remains a widely used method for electrically interconnecting two locations within a package (e.g., between the die pads of a semiconductor die and the leads of a leadframe). In connection with the formation of wire loops and / or ribbon loops in specific applications, a cleaver can be used to cut into conductive materials (e.g., circular cross-section wires, ribbon wires, etc.) to assist in cutting the completed wire loop from the wire supply. The use of such a cleaver is disclosed in U.S. Patent Nos. 4,976,392 and 8,141,765 (which relate to wire bonding systems), and the entire contents of these U.S. Patents are incorporated herein by reference.

[0005] It is expected that improved methods for cutting wires on wire bonding systems, as well as improved cutting blades and associated wire bonding systems, will be provided. Summary of the Invention

[0006] According to an exemplary embodiment of the present invention, a wire bonding system is provided. The wire bonding system includes a bonding tool (e.g., a wire bonding tool, a wedge bonding tool also known as a wedge, etc.). The wire bonding system also includes a cutting blade disposed adjacent to the bonding tool. The cutting blade defines a face on one side adjacent to its tip. The face is configured to contact the wire prior to a cutting operation.

[0007] According to other embodiments of the present invention, the wire bonding system described in the previous paragraph can have any one or more of the following features: the cutting knife is configured to contact the bonding tool prior to the cutting operation after the wire bonding operation is completed; the cutting knife is configured to contact the bonding tool during the cutting operation after the wire bonding operation is completed; the face is configured to provide resistance to the cutting knife to prevent over cutting of the wire; the cutting knife defines another side facing the bonding tool, the another side being opposite the first side, the first side defining another face adjacent to the face, the face and the another face meeting at an intersection region, the face and the another face being non-parallel to each other; the cutting knife defines another side facing the bonding tool, the another side being opposite the first side, the first side defining another face adjacent to the face, the face being configured at a first angle with respect to a vertical axis on the wire bonding system, the another face being configured at a second angle with respect to the vertical axis of the wire bonding system, the first angle being different than the second angle; the first angle is greater than the second angle; further comprising a wire guide configured to direct the wire towards a location below the bonding tool, wherein a portion of the wire adjacent to a tip portion of the cutting knife defines a third angle with respect to the vertical axis of the wire bonding system after the wire loop is formed but prior to the cutting operation, the first angle being greater than the third angle; further comprising a monitoring system for monitoring a resistance characteristic of the cutting knife as the cutting knife cuts into the wire on the wire bonding system; further comprising a motion system configured to raise and lower the cutting knife in order to cut the wire on the wire bonding system; the resistance characteristic is related to an electrical characteristic of the motion system; the resistance characteristic is related to at least one of a current of the motion system, a speed of a portion of the motion system, and a position of a portion of the motion system; the motion system is configured to stop lowering the cutting knife when the resistance characteristic reaches a predetermined value; and / or the tip portion comprises a stepped portion configured to limit penetration of the cutting knife into the wire during the cutting operation.

[0008] According to another exemplary embodiment of the present invention, a wire bonding system is provided. The wire bonding system includes a bonding tool. The wire bonding system further includes a cutting knife disposed adjacent to the bonding tool. The cutting knife defines a first side and a second side. The first side faces the bonding tool. The second side is opposite the first side. The second side defines a first flat portion adjacent to a tip portion of the cutting knife and a second flat portion adjacent to the first flat portion. The first flat portion and the second flat portion meet at an intersection region. The first flat portion and the second flat portion are non-parallel to each other. The intersection region is configured to contact a wire prior to a cutting operation.

[0009] According to other embodiments of the present application, the wire bonding system described in the previous paragraph can have any one or more of the following features: the cutting knife is configured to contact the bonding tool prior to the cutting operation after the wire bonding operation is completed; the cutting knife is configured to contact the bonding tool during the cutting operation after the wire bonding operation is completed; the first flat portion is configured to provide resistance to the cutting knife to prevent over cutting of the wire; the first flat portion is configured at a first angle relative to a vertical axis on the wire bonding system and the second flat portion is configured at a second angle relative to the vertical axis of the wire bonding system, the first angle being different than the second angle; the first angle is greater than the second angle; further comprising a wire guide configured to direct the wire toward a location below the bonding tool, wherein, after the wire loop is formed but prior to the cutting operation, a portion of the wire adjacent to the tip portion of the cutting knife defines a third angle relative to the vertical axis of the wire bonding system, the first angle being greater than the third angle; further comprising a monitoring system for monitoring a resistance characteristic of the cutting knife as the cutting knife cuts into the wire on the wire bonding system; further comprising a motion system configured to raise and lower the cutting knife to cut the wire on the wire bonding system; the resistance characteristic is related to an electrical characteristic of the motion system; the resistance characteristic is related to at least one of a current of the motion system, a speed of a portion of the motion system, and a position of a portion of the motion system; the motion system is configured to stop lowering the cutting knife when the resistance characteristic reaches a predetermined value; and / or the tip portion includes a stepped portion configured to limit penetration of the cutting knife into the wire during the cutting operation.

[0010] According to still another exemplary embodiment of the present application, a wire bonding system is provided. The wire bonding system includes a bonding tool. The wire bonding system further includes a cutting knife disposed adjacent to the bonding tool. The cutting knife defines a first side and a second side. The first side faces the bonding tool. The second side is opposite the first side. The second side defines a first flat portion adjacent to a tip portion of the cutting knife and a second flat portion adjacent to the first flat portion. The first flat portion is configured at a first angle relative to a vertical axis on the wire bonding system. The second flat portion is configured at a second angle relative to the vertical axis of the wire bonding system. The first angle is different than the second angle. The first flat portion and the second flat portion meet at an intersection region, wherein the intersection region is configured to contact the wire prior to the cutting operation.

[0011] According to other embodiments of the present application, the wire bonding system described in the previous paragraph can have any one or more of the following features: the cutting knife is configured to contact the bonding tool prior to the cutting operation after the wire bonding operation is completed; the cutting knife is configured to contact the bonding tool during the cutting operation after the wire bonding operation is completed; the first flat portion is configured to provide resistance to the cutting knife to prevent over cutting of the wire; the first angle is greater than the second angle; further comprising a monitoring system for monitoring a resistance characteristic of the cutting knife as the cutting knife cuts into the wire on the wire bonding system; further comprising a motion system configured to raise and lower the cutting knife to cut the wire on the wire bonding system; the resistance characteristic is related to an electrical characteristic of the motion system; the resistance characteristic is related to at least one of a current of the motion system, a speed of a portion of the motion system, and a position of a portion of the motion system; the motion system is configured to stop lowering the cutting knife when the resistance characteristic reaches a predetermined value; the tip portion comprises a stepped portion configured to limit penetration of the cutting knife into the wire during the cutting operation; and / or further comprising a wire guide configured to guide the wire toward a position below the bonding tool, wherein, after the wire loop is formed but prior to the cutting operation, a portion of the wire adjacent to the tip portion of the cutting knife defines a third angle relative to a vertical axis of the wire bonding system, the first angle being greater than the third angle.

[0012] According to still another exemplary embodiment of the present application, a method of cutting a wire in connection with a wire bonding system is provided. The method comprises the steps of: (a) providing a bonding tool; (b) providing a cutting knife adjacent to the bonding tool; (c) moving the cutting knife to contact a portion of the wire; and (d) cutting another portion of the wire away from the portion of the wire.

[0013] According to other embodiments of the present application, the method described in the previous paragraph can have any one or more of the following features: step (c) comprises contacting the bonding tool with the cutting knife prior to step (d); step (c) comprises contacting the bonding tool with the cutting knife during step (d); further comprising step (e) of providing a monitoring system to monitor a resistance characteristic of the cutting knife during step (d); and / or further comprising a step of terminating step (d) when the resistance characteristic reaches a predetermined value.

[0014] According to still another exemplary embodiment of the present application, a cutting knife for a wire bonding system is provided. The cutting knife comprises: a body portion extending to a tip portion, the tip portion comprising a first side and a second side, the first side defining a first face and a second face, the first face and the second face being non-parallel to each other.

[0015] According to other embodiments of the invention, the cutting blade described in the preceding paragraph may have any one or more of the following features: at least one of a first face and a second face is configured to provide resistance to the cutting blade to prevent overcutting of the wire; the first face is adjacent to the tip of the tip portion, the first face being configured to provide resistance to the cutting blade to prevent overcutting of the wire; the first face is adjacent to the tip of the tip portion, wherein the first face is configured at a first angle relative to the vertical axis, the second face is configured at a second angle relative to the vertical axis, the first angle being different from the second angle; the first angle being greater than the second angle; the cutting blade is configured to contact the portion of the wire adjacent to the tip of the cutting blade after the arc is formed but before the cutting operation, the arc defining a third angle relative to the vertical axis, the first angle being greater than the third angle; the tip portion includes a stepped portion, the stepped portion being configured to limit the penetration of the cutting blade into the wire during the cutting operation; and / or the stepped portion defines a step width such that control signals of a monitoring system used in connection with the cutting blade can be monitored.

[0016] According to another exemplary embodiment of the present invention, another cutting blade for a wire bonding system is provided. The cutting blade includes: a body portion extending to a distal portion, the distal portion including a first side and a second side, the first side defining a first face and a second face, the first face and the second face defining an intersection point configured to contact the wire during a cutting operation.

[0017] According to other embodiments of the invention, the cutting blade described in the preceding paragraph may have any one or more of the following features: at least one of a first face and a second face is configured to provide resistance to the cutting blade to prevent overcutting of the wire; the first face is adjacent to the tip of the tip portion, and the first face is configured to provide resistance to the cutting blade to prevent overcutting of the wire; the first face is adjacent to the tip of the tip portion, wherein the first face is configured at a first angle relative to the vertical axis, and the second face is configured at a second angle relative to the vertical axis, the first angle being different from the second angle; the first angle being greater than the second angle; the cutting blade is configured to adjust the portion of the wire adjacent to the tip of the cutting blade after the arc is formed but before the cutting operation, the arc defining a third angle relative to the vertical axis, the first angle being greater than the third angle; the tip portion includes a stepped portion, the stepped portion being configured to limit the penetration of the cutting blade into the wire during the cutting operation; and / or the stepped portion defines a step width such that control signals of a monitoring system used in connection with the cutting blade can be monitored.

[0018] According to still another exemplary embodiment of the present application, there is provided still another cutting knife for a wire bonding system. The cutting knife includes a body portion extending to a tip portion, the tip portion including a first side and a second side, the first side defining a first face and a second face, the first face disposed at a first angle relative to a vertical axis and the second face disposed at a second angle relative to the vertical axis, the second angle being different than the first angle.

[0019] According to other embodiments of the present application, the cutting knife described in the previous paragraph can have any one or more of the following features: at least one of the first face and the second face is configured to provide resistance to the cutting knife to prevent over cutting of the wire; the first face is adjacent to a tip of the tip portion, the first face configured to provide resistance to the cutting knife to prevent over cutting of the wire; the first face is adjacent to a tip of the tip portion, wherein the first angle is greater than the second angle; the cutting knife is configured to adjust a portion of the wire adjacent to the tip of the cutting knife after formation of a wire loop and prior to a cutting operation, the wire loop defining a third angle relative to the vertical axis, the first angle being greater than the third angle; the tip portion includes a stepped portion configured to limit penetration of the cutting knife into the wire during the cutting operation; and / or the stepped portion defines a step width such that a control signal of a monitoring system used in connection with the cutting knife can be monitored.

[0020] According to still another exemplary embodiment of the present application, there is provided still another cutting knife for a wire bonding system. The cutting knife includes a body portion extending to a tip portion, the tip portion including a first side and a second side, the first side defining a first face and a second face, the tip portion further including a stepped portion configured to limit penetration of the cutting knife into the wire during a cutting operation.

[0021] According to other embodiments of the present application, the cutting knife described in the previous paragraph can have any one or more of the following features: at least one of the first face and the second face is configured to provide resistance to the cutting knife to prevent over cutting of the wire; the first face is adjacent to the tip portion of the tip portion of the cutting knife, the first face is configured to provide resistance to the cutting knife to prevent over cutting of the wire; the first face is configured at a first angle relative to a vertical axis, the second face is configured at a second angle relative to the vertical axis, the first angle is different than the second angle; the first face is adjacent to the tip portion of the tip portion of the cutting knife, wherein the first angle is greater than the second angle; the cutting knife is configured to contact a portion of the wire adjacent to the tip portion of the cutting knife after a wire arc is formed but prior to a cutting operation, the wire arc defining a third angle relative to the vertical axis, the first angle being greater than the third angle; the stepped portion defines a stepped width such that a control signal of a monitoring system used in connection with the cutting knife can be monitored; and / or the stepped portion defines a stepped height such that the cutting knife tip portion can cut to a predetermined percentage of a diameter of the wire. BRIEF DESCRIPTION OF DRAWINGS

[0022] The present application will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings. To the extent that any matter incorporated by reference challenges any definition found in this detailed description, the definition found in the detailed description prevails. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following Figures:

[0023] Figure 1 is a block diagram schematic side view of a wire bonding system for bonding wire (e.g., round wire, ribbon wire, etc.) according to an example embodiment of the present application;

[0024] Figures 2A-2D is a cross-sectional side view of elements of the wire bonding system, illustrating a cutting operation according to an example embodiment of the present application;

[0025] Figures 3A-3G is a cross-sectional side view and block diagram schematic view of elements of the wire bonding system, illustrating a cutting operation according to one or more example embodiments of the present application;

[0026] Figures 4A-4D is a cross-sectional side view and block diagram schematic view of elements of another wire bonding system, illustrating a cutting operation according to an example embodiment of the present application;

[0027] Figure 5 is a cross-sectional side view and block diagram schematic view of elements of still another wire bonding system according to an example embodiment of the present application;

[0028] Figure 6 is a cross-sectional side view and block diagram schematic view of elements of still another wire bonding system according to an example embodiment of the present application; and

[0029] Figure 7 is a flowchart illustrating a method of cutting wire material in connection with a wire bonding system, according to an example embodiment of the present application. DETAILED DESCRIPTION

[0030] The terms "wire material," "ribbon," and "conductive material" are used herein to generally describe the material that is bonded by a wire bonding system (e.g., a wedge bonding system). It is understood that the wire bonding system can bond wire material or ribbon material, as desired in a given application. Thus, it is understood that these terms can be used interchangeably without intending to limit one another. For example, as used herein, the term "wire material" is intended to refer to round wire material (i.e., wire material having a circular cross-section), ribbon wire material, and the like.

[0031] Wire bonding is widely used as a reliable and cost-effective interconnection method in semiconductor packaging. In wedge bonding (including ribbon bonding), the wire material is sometimes cut after the last bond is completed, using a cutting knife. There are generally two ways to cut wire material in various wire bonding processes: rear-cut applications and front-cut applications. For front-cut applications, the cutter and wire guide are mounted on different sides of the bonding tool; for rear-cut applications, the cutter and wire guide are on the same side. A predetermined cut depth can be defined before the bonding operation, so that the bonding process can continue with the desired operation. For front-cut applications, the cut depth can be predetermined to be > 100% of the wire material diameter. Rear-cut applications can require a more precise cutting process.

[0032] To have a stable and controlled cutting process, the cutting knife (e.g., cutting knife 112) can be as close as desired (and possibly even touching) the bonding tool when the cutting knife is lowered and cuts into the wire material (e.g., wire material 116) at the desired cut point. Due to process variations, the cutting knife can not always touch the bonding tool. In addition, the cutting knife can sometimes cut into the wire material at an undesirable point, resulting in an unstable cut depth and tail length. When the cut depth is less than a predetermined threshold (e.g., < 65% of the wire material diameter or "shallow limit"), the wire material cannot be terminated and the bonding process stops. When the cut depth is greater than another predetermined threshold (e.g., > 85% of the wire material diameter or "deep limit"), the wire material cannot be fed under the bonding tool and the bonding process also stops. In particular embodiments, a "cutting window" can be defined as the difference between the maximum value of the cut depth adjustment (e.g., a parameter that limits the cut depth of the cutting knife) and the minimum value of the cut depth adjustment. A small cutting window makes the cutting process unstable and challenging. A larger cutting window is generally desired.

[0033] The particular embodiments illustrated and described herein provide a unique tip geometry design to ensure a large cutting window and consistent cutting location. Such embodiments can result in consistent wire tail length and / or consistent cutting depth, such that a stable cutting process can be achieved. The wire exiting the wire guide has an angle (e.g., ~40°, 20° to 60°, etc.) (see, e.g., FIG. 1) relative to the vertical axis of the wire bonding machine. In order to prevent the tip of the cutting knife from cutting into the wire before it reaches the desired cutting point, the face near the tip of the cutting knife can have a larger angle a (e.g., ~60°, 40° to 80°, etc.) (see, e.g., FIG. 1) than the wire angle b. The optimal angle a and width of the "face" ensure that the cutting knife slides along the wire at the face and / or intersection (e.g., "corner") of the cutting knife before the tip reaches the cutting location (e.g., cutting location 136). Despite variations in the process (e.g., setup, vibration, etc.), the cutting knife tip cuts into the wire as desired at the optimal cutting location (e.g., cutting location 136), resulting in consistent cutting depth and tail length. In addition, the design of the face increases the resistance to the cutting knife and prevents overcutting (i.e., cutting beyond the depth limit) as the tip approaches the depth limit, resulting in a larger (e.g., >2x) cutting window. The optimal width of the face can also eliminate undesirable marks at the wire that can show up at the first bond of the next wire in the next bonding operation. Figure 3B ) (see, e.g., FIG. 1). In order to prevent the tip of the cutting knife from cutting into the wire before it reaches the desired cutting point, the face near the tip of the cutting knife can have a larger angle a (e.g., ~60°, 40° to 80°, etc.) (see, e.g., FIG. 1) than the wire angle b. The optimal angle a and width of the "face" ensure that the cutting knife slides along the wire at the face and / or intersection (e.g., "corner") of the cutting knife before the tip reaches the cutting location (e.g., cutting location 136). Despite variations in the process (e.g., setup, vibration, etc.), the cutting knife tip cuts into the wire as desired at the optimal cutting location (e.g., cutting location 136), resulting in consistent cutting depth and tail length. In addition, the design of the face increases the resistance to the cutting knife and prevents overcutting (i.e., cutting beyond the depth limit) as the tip approaches the depth limit, resulting in a larger (e.g., >2x) cutting window. The optimal width of the face can also eliminate undesirable marks at the wire that can show up at the first bond of the next wire in the next bonding operation. Figure 3B ) (see, e.g., FIG. 1). In order to prevent the tip of the cutting knife from cutting into the wire before it reaches the desired cutting point, the face near the tip of the cutting knife can have a larger angle a (e.g., ~60°, 40° to 80°, etc.) (see, e.g., FIG. 1) than the wire angle b. The optimal angle a and width of the "face" ensure that the cutting knife slides along the wire at the face and / or intersection (e.g., "corner") of the cutting knife before the tip reaches the cutting location (e.g., cutting location 136). Despite variations in the process (e.g., setup, vibration, etc.), the cutting knife tip cuts into the wire as desired at the optimal cutting location (e.g., cutting location 136), resulting in consistent cutting depth and tail length. In addition, the design of the face increases the resistance to the cutting knife and prevents overcutting (i.e., cutting beyond the depth limit) as the tip approaches the depth limit, resulting in a larger (e.g., >2x) cutting window. The optimal width of the face can also eliminate undesirable marks at the wire that can show up at the first bond of the next wire in the next bonding operation.

[0034] In particular embodiments, the cutting knife includes a step (e.g., stepped portion), as in U.S. Patent No. 8,141,765. The step height (e.g., step height 140) can be designed as a certain percentage of the wire diameter, such that the cutting knife tip can cut to a predetermined percentage (e.g., 75%) of the wire diameter, or within a desired cutting depth range (e.g., 65% to 85% of the wire diameter). The step width (e.g., step width 142) has multiple functions, including physically preventing the cutting knife from cutting deeper into the wire, and generating a motion control signal to stop the drive of the cutting motion. Before the step width contacts the wire, the tip of the cutting knife can smoothly cut into the wire, and the resistance to further cutting can be detected (e.g., with a monitoring system). When the step contacts the wire, the step width rapidly generates an increased resistance that prevents the tip from cutting deeper. However, for some motion control systems, the drive force that moves the cutting knife downward can be much greater than the resistance generated by the stepped width. Thus, the step width can not be effective in stopping the cutting. For such motion control systems, a control signal can be used as desired to stop the drive force so that the cutting knife will stop moving.

[0035] ​​A variety of types of control signals can be monitored. For example, motor current can be monitored (e.g., current to a motor system that raises and lowers a cutting blade) to monitor resistance characteristics (e.g., resistance characteristics of a cutting blade as it cuts into wire on a wire bonding system). Such control signals can be monitored for a variety of cutting blades within the scope of the present invention (not just cutting blades with steps). If resistance suddenly increases (e.g., due to a step width contacting wire, due to an intersection point contacting wire, due to a face of the cutting blade contacting wire, etc.), the driving force (e.g., lowering of the cutting blade) can be set to zero and the cutting process stopped.

[0036] According to certain aspects of the present invention, step width can be optimized. To generate a strong signal, a large step width is desirable. However, a step width that is too wide pushes the cutting blade tip away from the bonding tool edge, reducing the efficiency of the cutting process. A small step width (e.g., step width 142) allows for an efficient cutting process, but the control signal can be too small to accurately stop the cutting process.

[0037] Referring now to the drawings, and in particular to Figure 1 A wire bonding system 100 is illustrated. The wire bonding system 100 is illustrated as defining a vertical axis 104. The wire bonding system 100 includes a bonding head assembly 102. The bonding head assembly 102 is illustrated as supporting (or including) a bonding tool 110 (e.g., a wire bonding tool, a wedge bonding tool also known as a wedge-lap tool, etc.), a cutting blade 112 (disposed proximate the bonding tool 100), and a wire guide 114. The wire bonding system 100 also includes a support structure 120 for supporting a workpiece (e.g., a substrate, a semiconductor element, a die, a chip, etc.). The wire bonding system 100 also includes a motion system 106 and a monitoring system 108. The motion system 106 is configured to raise and lower the cutting blade 112 to cut wire on the wire bonding system 100. The monitoring system 108 (e.g., including a computer, a processor, etc.) monitors resistance characteristics of the cutting blade 112 (e.g., as the cutting blade 112 cuts into wire on the wire bonding system 100). Examples of such resistance characteristics can be: electrical characteristics of the motion system 106 (e.g., current associated with the motion system 106); velocity of a portion of the motion system (e.g., a portion of the motion system that can include and / or carry the cutting blade 112); position of a portion of the motion system (e.g., a portion of the motion system that can include and / or carry the cutting blade 112); and the like. The monitoring system 108 can be configured to stop lowering of the cutting blade 112 when the resistance characteristics reach a predetermined value.

[0038] In Figures 2A-2D , Figures 3A-3G , Figures 4A-4D , Figure 5 and Figure 6Figures 2A-2D , Figures 3A-3G , Figures 4A-4D , Figure 5 and Figure 6 each of which illustrates details of exemplary elements of a wire bonding system according to exemplary embodiments of the present application. Thus, each of these examples Figure 1 may be part of a more general wire bonding system 100 illustrated in

[0039] Referring now to Figures 2A-2D , a lower portion of each of the bonding tool 110, the cutting knife 112, and the wire guide 114 is illustrated. In Figures 2A-2D , a wire arc is formed, and the cutting operation is completed. With particular reference to Figure 2A , the support structure 120 is illustrated supporting the substrate 118. The bonding tool 110 is illustrated having formed a bond 116a (e.g., a first bond) from the wire 116 at a bond location (e.g., a first bond location). The wire 116 is provided by the wire guide 114 (e.g., before, during, and / or after the bond 116a is formed).

[0040] Referring now to Figure 2B , a wire arc 116b including a second bond 116c is formed from the wire that has extended out a length from the bond 116a. The cutting operation can be completed after the second bond 116c is formed. Referring now to Figure 2C , the cutting knife 112 is illustrated being lowered (e.g., by the motion system 106) in connection with the cutting operation. Prior to the cutting operation, a portion (e.g., a face, an intersection, etc.) of the cutting knife 112 can contact a portion (e.g., a portion that will not be cut) of the wire 116 (see, e.g., Figure 3C and Figure 3D ). Further, prior to the cutting operation, the cutting knife 112 can contact the bonding tool 110 (see, e.g., Figure 3E ). In Figure 2C , the cutting knife 112 is illustrated cutting into (e.g., penetrating the wire, etc.) the wire 116. The cutting knife 112 can continue to cut into the wire 116 until a particular threshold is reached (e.g., when a resistance threshold is reached, when a depth threshold is reached, when 65-85% of the wire diameter is cut, when 75% of the wire diameter is cut, etc.).

[0041] Referring now to Figure 2D , after the cutting operation, the bond head assembly 102 (not illustrated in Figures 2A-2D , but see Figure 1 ) has moved laterally (e.g., right along the x-axis) and vertically (e.g., up along the z-axis) such that the bonding tool 110, the cutting knife 112, and the wire guide 114 are illustrated away from the wire arc 116b. As​Figure 2D As shown, the wire tail 116d is positioned below the welding tool 110 for use in relation to the formation of the next wire arc.

[0042] Now for reference Figures 3A-3G The cutting blade 112 is illustrated in more detail before the cutting operation (i.e., Figures 3A-3B ) and during the cutting operation (i.e. Figures 3C-3G ).although Figures 3A-3G The images are provided as a series of images appearing sequentially in time, but it should be understood that specific images may be included (or excluded) from various exemplary embodiments of the invention.

[0043] The cutting blade 112 is illustrated as including a body portion 113 extending to a distal portion 115 (e.g., terminating at the distal portion). A first side 122 (facing the welding tool 110) and a second side 124 (opposite to the first side 122) are illustrated as being disposed on opposite sides of the body portion 113 and / or the distal portion 115. The second side 124 includes a first flat portion 126 and a second flat portion 128. The first flat portion 126 (or face) may be configured to contact the wire 116 prior to the cutting operation (e.g., see...). Figure 3D The first flat portion 126 (e.g., a surface) and the second flat portion 128 (e.g., a surface) define an intersecting region 130 (e.g., a point, an edge, an intersecting edge, a protruding area, etc.). This intersecting region 130 can be configured to contact the wire prior to the cutting operation (e.g., see...). Figure 3C A first side 122 and a second side 124 (especially the first flat portion 126) define a tip 132 (e.g., a dot, a cut edge, etc.). The tip 132 can be used to cut the wire 116 at a desired cut position 136 adjacent to the edge 134 of the bonding tool 110. The first flat portion 126 is illustrated as being configured at a first angle α relative to the vertical axis 104 (of the wire bonding system 100). The second flat portion 128 is illustrated as being configured at a second angle β relative to the vertical axis 104. As shown, the first angle α is different from the second angle β; specifically, in the illustrated embodiment, the first angle α is greater than the second angle β. The wire 116 is positioned at a third angle relative to the vertical axis 104. (e.g., 20° to 60°, ~40°, etc.) are provided (e.g., see [link]). Figure 3B More specifically, after the arc is formed but before the cutting operation, the portion of the wire adjacent to the tip of the cutting blade defines an angle relative to the vertical axis of the wire bonding system. The angle of the wire It can be less than the first angle α. Furthermore, the second angle β can be less than the third angle.

[0044] Describe in order,Figures 3A-3B FIG. illustrates the cutting knife 112 after the second weld 116c (see Figure 2B ) is formed. Figures 3C-3G FIG. illustrates the lowering of the cutting knife 112 and the cutting operation on the wire 116. Figure 3C FIG. illustrates the intersection region 130 contacting the wire 116 prior to the cutting operation (where the cutting operation is shown in Figures 3F-3G ). As the cutting knife 112 is lowered further as shown in Figure 3D , the first flat portion 126 (e.g., face) contacts the wire 116 prior to the cutting operation (where the cutting operation is shown in Figures 3F-3G ). The first flat portion 126 can provide higher resistance to the cutting knife 112 to prevent over cutting of the wire 116 as the cutting knife 112 approaches a “deep limit” (e.g., > 85% of the wire diameter). As the cutting knife 112 is lowered further as shown in Figure 3E , the cutting knife 112 can contact the bonding tool 110 prior to (and / or during, and / or after) the cutting operation. Figures 3F-3G FIG. illustrates the cutting operation (similar to the cutting operation shown in Figure 2C ).

[0045] As set forth above, the cutting knives according to aspects of the present disclosure can include a “stepped” portion. With particular reference to Figures 4A-4D , the cutting knife 112a is illustrated prior to the cutting operation (i.e., before Figures 4A-4B ) and during the cutting operation (i.e., during Figures 4C-4D ). The cutting knife 112a is similar to the cutting knife 112 (with various of the features described above with respect to Figures 2A-2D and Figures 3A-3G ) except that the cutting knife 112a includes a stepped portion 138. The stepped portion 138 is illustrated as defining a 90 degree angle; however, it should be appreciated that the stepped portion 138 can define any angle between 0 degrees and 180 degrees. Particular exemplary ranges include: 80 degrees to 100 degrees; 70 degrees to 110 degrees; 60 degrees to 120 degrees; and 50 degrees to 130 degrees. It should be appreciated that the angle defined by the stepped portion can include a curved, rounded, and / or chamfered shape, whereby the angle can be understood to be defined by one or more tangents of the curved, rounded, and / or chamfered shape (e.g., at or near the termination point of such curved, rounded, and / or chamfered shape).

[0046] The cutting knife 112a is illustrated as including a body portion 113a that extends to (e.g., terminates at) the tip portion 115a (e.g., see Figure 4C). A first side 122a (facing the bonding tool 110) and a second side 124a (opposite the first side 122a) are illustrated as being disposed on each of the two sides of the body portion 113a and / or the tip portion 115a. The second side 124a includes a first flat portion 126a and a second flat portion 128a. The first flat portion 126a (or face) can be configured to contact the wire 116 prior to a cutting operation. The first flat portion 126a (e.g., face) and the second flat portion 128a (e.g., face) define an intersection region 130a (e.g., edge, intersecting edge, protruding region, etc.). The first side 122a and the second side 124a (and particularly the first flat portion 126a) define a tip portion 132a (e.g., point, cutting edge, etc.). The tip portion 132a can be used to cut into the wire 116 at a desired cutting location 136 proximate an edge 134 of the bonding tool 110. The first flat portion 126a is illustrated as being disposed at a first angle a a configuration. The second flat portion 128a is illustrated as being disposed at a second angle β a configuration. As illustrated, the first angle a a is different than the second angle β a ; specifically, the first angle a a is at a greater angle than the second angle β a . The stepped portion 138 includes a step height 140 and a step width 142. The step height 140 can be designed as a predetermined percentage (e.g., 75%) of the wire diameter, such that the cutting knife 112a can cut up to the predetermined percentage (e.g., 75%) of the wire diameter. The predetermined percentage can be within a desired cutting depth range (e.g., 65% to 85% of the wire diameter). The step width 142 has multiple functions, including physically preventing the cutting knife 112a from cutting deeper into the wire 116, as well as generating a motion control signal to stop the drive (e.g., with a motor) of the cutting motion.

[0047] Figures 2A-2D 、 Figures 3A-3G and Figures 4A-4D illustrate a "back-cut" condition (i.e., where the conductive material is cut on the bonding side proximate the wire guide 114). The present disclosure is not limited to "back-cut" applications as such. Figure 5 and Figure 6 illustrate the cutting knife 112 and the cutting knife 112a, respectively, in a "front-cut" application. Specifically, the cutting knife 112 and the cutting knife 112a are illustrated as being prior to a cutting operation.

[0048] Figure 7is a flowchart according to particular exemplary embodiments of the present application. As will be appreciated by those skilled in the art, particular steps included in the flowchart can be omitted; particular additional steps can be added; and the order of steps can be changed from that shown. Dotted lines can be considered "optional" in particular embodiments.

[0049] Figure 7 is a flowchart illustrating a method of cutting wire in connection with a wire bonding system. At step 700, a bonding tool (e.g., bonding tool 110) is provided. At step 702, a cutting knife (e.g., cutting knife 112, cutting knife 112a, etc.) is provided adjacent to the bonding tool. At step 704, the cutting knife is moved to contact a portion of a wire (e.g., see portion 128 of wire 116 in Figure 3C intersects region 130 of the wire 116, and Figure 3D intersects first flat portion 126 of the wire 116) is cut away from the portion of the wire (e.g., see portion 128 of wire 116 in Figure 3E is cut at a point of the wire 116 that is different than the point of contact in Figure 3C and Figure 3D At optional step 708, a monitoring system is provided to monitor resistance characteristics of the cutting knife during step 706. At optional step 710, cutting (of step 706) is terminated after the resistance characteristics reach a predetermined value (e.g., a current reading of the motor exceeds a predetermined threshold, a signal corresponding to frictional or mechanical resistance of the cutting knife exceeds a predetermined threshold, etc.).

[0050] With various embodiments of the present application, a well-controlled cutting process (e.g., resulting in accurate cut depths and consistent tail lengths) is provided. Particular cutting knives and associated control systems of the present application stabilize and make the cutting process consistent. In addition, the cutting position can be maintained at an optimal position, resulting in consistent tail lengths and cut depths. Control of the cut depth prevents undercuts (e.g., where the wire is not terminated and the bonding process stops) or overcuts (e.g., where no wire is fed to the bonding tool). In addition, particular embodiments of the present application can provide advantages such as a wider cutting window, more accurate cut depths, more consistent tail lengths, higher throughput, and higher yield.

[0051] While the present application has been illustrated and described with reference to specific embodiments thereof, it is not intended that it be limited thereto. Various modifications in detail can be made therein by those skilled in the art without departing from the scope and spirit of the present application.

Claims

1. A wire bonding system, comprising: a bonding tool; and a cutting knife disposed adjacent to the bonding tool, the cutting knife defining a face on one side of the cutting knife adjacent to a tip portion of the cutting knife, the face configured to contact a wire prior to a cutting operation.

2. The wire bonding system of claim 1, wherein, The cutting knife is configured to contact the bonding tool prior to the cutting operation after completion of a wire bonding operation.

3. The wire bonding system of claim 1, wherein, The cutting knife is configured to contact the bonding tool during the cutting operation after completion of a wire bonding operation.

4. The wire bonding system of claim 1, wherein, The face is configured to provide resistance to the cutting knife to prevent overcutting of the wire.

5. The wire bonding system of claim 1, wherein, The cutting knife defines another side facing the bonding tool, the another side opposite the one side, the one side defining another face adjacent to the face, the face and the another face meeting at an intersection region, the face and the another face not parallel to each other.

6. The wire bonding system of claim 1, wherein, The cutting knife defines another side facing the bonding tool, the another side opposite the one side, the one side defining another face adjacent to the face, the face configured at a first angle relative to a vertical axis on the wire bonding system, the another face configured at a second angle relative to the vertical axis of the wire bonding system, the first angle different than the second angle.

7. The wire bonding system of claim 6, wherein, The first angle is greater than the second angle.

8. The wire bonding system of claim 6, further comprising a wire guide configured to guide a wire toward a location below the bonding tool, wherein a portion of the wire adjacent to the tip portion of the cutting knife defines a third angle relative to the vertical axis of the wire bonding system after a wire loop is formed but prior to the cutting operation, the first angle greater than the third angle.

9. The wire bonding system of claim 1, further comprising a monitoring system to monitor a resistance characteristic of the cutting knife as the cutting knife cuts into the wire on the wire bonding system.

10. The wire bonding system of claim 9, further comprising a motion system configured to raise and lower the cutting knife to cut the wire on the wire bonding system.

11. The wire bonding system of claim 10, wherein, The resistance characteristic is related to an electrical characteristic of the motion system.

12. The wire bonding system of claim 10, wherein, The resistance characteristic is related to at least one of a current of the motion system, a speed of a portion of the motion system, and a position of a portion of the motion system.

13. The wire bonding system of claim 10, wherein, The motion system is configured to stop lowering the cutting knife when the resistance characteristic reaches a predetermined value.

14. The wire bonding system of claim 1, wherein, The tip portion includes a stepped portion configured to limit penetration of the cutting knife into the wire during the cutting operation.

15. A wire bonding system, comprising: a bonding tool; and a cutting knife disposed adjacent to the bonding tool, the cutting knife defining a first side and a second side, the first side facing the bonding tool, the second side opposite the first side, the second side defining a first flat portion adjacent to a tip portion of the cutting knife and a second flat portion adjacent to the first flat portion, the first flat portion and the second flat portion meeting at an intersection region, the first flat portion and the second flat portion being non-parallel to each other, wherein the intersection region is configured to contact wire prior to a cutting operation.

16. The wire bonding system of claim 15, wherein, the cutting knife is configured to contact the bonding tool prior to a cutting operation after a wire bonding operation is completed.

17. The wire bonding system of claim 15, wherein, the cutting knife is configured to contact the bonding tool during a cutting operation after a wire bonding operation is completed.

18. The wire bonding system of claim 15, wherein, the first flat portion is configured to provide resistance to the cutting knife to prevent overcutting of the wire.

19. The wire bonding system of claim 15, wherein, the first flat portion is configured at a first angle relative to a vertical axis on the wire bonding system and the second flat portion is configured at a second angle relative to the vertical axis of the wire bonding system, the first angle being different than the second angle.

20. The wire bonding system of claim 19, wherein, the first angle is greater than the second angle.

21. The wire bonding system of claim 19, further comprising a wire guide configured to direct a wire toward a location below the bonding tool, wherein, a portion of the wire adjacent to the tip portion of the cutting knife after a wire loop is formed but prior to a cutting operation defines a third angle relative to the vertical axis of the wire bonding system, the first angle being greater than the third angle.

22. The wire bonding system of claim 15, further comprising a monitoring system for monitoring a resistance characteristic of the cutting knife as the cutting knife cuts into wire on the wire bonding system.

23. The wire bonding system of claim 22, further comprising a motion system configured to raise and lower the cutting knife to cut the wire on the wire bonding system.

24. The wire bonding system of claim 23, wherein, the resistance characteristic is related to an electrical characteristic of the motion system.

25. The wire bonding system of claim 23, wherein, the resistance characteristic is related to at least one of a current of the motion system, a speed of a portion of the motion system, and a position of a portion of the motion system.

26. The wire bonding system of claim 23, wherein, the motion system is configured to stop lowering the cutting knife when the resistance characteristic reaches a predetermined value.

27. The wire bonding system of claim 15, wherein, the tip portion includes a stepped portion configured to limit penetration of the cutting knife into the wire during a cutting operation.

28. A wire bonding system, comprising: a bonding tool; and a cutting knife disposed adjacent to the bonding tool, the cutting knife defining a first side and a second side, the first side facing the bonding tool, the second side opposite the first side, the second side defining a first flat portion adjacent to a tip portion of the cutting knife and a second flat portion adjacent to the first flat portion, the first flat portion being configured at a first angle relative to a vertical axis on the wire bonding system, the second flat portion being configured at a second angle relative to the vertical axis of the wire bonding system, the first angle being different than the second angle, wherein the first flat portion and the second flat portion meet at an intersection region, wherein the intersection region is configured to contact wire prior to a cutting operation.

29. The wire bonding system of claim 28, wherein, The cutting knife is configured to contact the bonding tool prior to a cutting operation after the wire bonding operation is completed.

30. The wire bonding system of claim 28, wherein, The cutting knife is configured to contact the bonding tool during a cutting operation after the wire bonding operation is completed.

31. The wire bonding system of claim 28, wherein, The first flat portion is configured to provide resistance to the cutting knife to prevent overcutting of the wire.

32. The wire bonding system of claim 28, wherein, The first angle is greater than the second angle.

33. The wire bonding system of claim 28, further comprising a monitoring system for monitoring a resistance characteristic of the cutting knife as the cutting knife cuts into the wire on the wire bonding system.

34. The wire bonding system of claim 33, further comprising a motion system configured to raise and lower the cutting knife to cut the wire on the wire bonding system.

35. The wire bonding system of claim 34, wherein, The resistance characteristic is related to an electrical characteristic of the motion system.

36. The wire bonding system of claim 34, wherein, The resistance characteristic is related to at least one of a current of the motion system, a speed of a portion of the motion system, and a position of a portion of the motion system.

37. The wire bonding system of claim 34, wherein, The motion system is configured to stop lowering the cutting knife when the resistance characteristic reaches a predetermined value.

38. The wire bonding system of claim 28, wherein, The tip portion includes a stepped portion configured to limit penetration of the cutting knife into the wire during a cutting operation.

39. The wire bonding system of claim 28, further comprising a wire guide configured to direct a wire toward a location below the bonding tool, wherein, A portion of the wire adjacent to the tip portion of the cutting knife defines a third angle relative to a vertical axis of the wire bonding system after a wire loop is formed but prior to a cutting operation, the first angle being greater than the third angle.

40. A method of cutting a wire in connection with a wire bonding system, comprising the steps of: (a) providing a bonding tool; (b) providing a cutting knife adjacent to the bonding tool; (c) moving the cutting knife to contact a portion of the wire; and (d) cutting another portion of the wire away from the portion of the wire.

41. The method of claim 40, wherein, Step (c) includes contacting the bonding tool with the cutting knife prior to step (d).

42. The method of claim 40, wherein, Step (c) includes contacting the bonding tool with the cutting knife during step (d).

43. The method of claim 40, further comprising the step (e) of providing a monitoring system to monitor a resistance characteristic of the cutting knife during step (d).

44. The method of claim 43, further comprising the step of terminating step (d) when the resistance characteristic reaches a predetermined value.

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