Active wire feeding in the formation of wire bonds

Abstract

The wire bonding apparatus comprises: a supply of bonding wire; a first motor for advancing the bonding wire from the supply; a wedge for performing wire bonding by forming a first bond and a second bond, the second bond being spaced a distance from the first bond; a wire guide adjacent the wedge for guiding the bonding wire toward the wedge; and a second motor for advancing the bonding wire into the wire guide, the second motor configured to feed a length of the bonding wire after forming the first bond and before forming the second bond, the length being longer than the distance between the first and second bonds.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 268,409, filed February 23, 2022, entitled "ACTIVE WIRE FEEDING IN FORMING WIRE BONDS," the disclosure of which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to active wire feeding in the formation of wire bonds. [Background technology]

[0003] In recent years, global transportation has begun to transition away from primarily fossil fuel powered powertrains and toward more sustainable energy sources, particularly electric motors powered by on-board energy storage. Vehicle manufacturers are striving to increase the efficiency and utility of such vehicles, including the performance of energy storage devices such as battery packs. Summary of the Invention

[0004] In a first aspect, a wire bonding apparatus comprises a supply of bonding wire; a first motor for advancing the bonding wire from the supply; a wedge for performing wire bonding by forming a first bond and a second bond, the second bond being spaced a distance from the first bond; a wire guide adjacent the wedge for guiding the bonding wire toward the wedge; and a second motor for advancing the bonding wire into the wire guide, the second motor configured to feed a length of the bonding wire after formation of the first bond and before formation of the second bond, the length being longer than the distance between the first and second bonds.

[0005] Implementations may include any or all of the following features: The wire bonding apparatus further comprises a clamp for the bonding wire. The clamp is positioned adjacent to the wire guide, and the second motor is positioned in front of the clamp in a direction of advancement of the bonding wire from the supply. The second motor is positioned immediately before the clamp in a direction of advancement of the bonding wire from the supply. The supply of bonding wire comprises a spool. The second motor has at least two wheels facing each other across the bonding wire. The wire bonding apparatus further comprises a cutter for cutting the bonding wire.

[0006] In a second aspect, a method includes positioning a bonding wire at a first location on a substrate; using a wire bonding head of a wire bonding machine to form a first wire bond between the bonding wire and the substrate at the first location; after forming the first wire bond, moving the wire bonding head from the first location to a second location on the substrate; while moving the wire bonding head, using a first motor of the wire bonding machine to actively feed a length of the bonding wire through the wire bonding head, the length being greater than a distance between the first and second locations; and using the wire bonding head to form a second wire bond between the bonding wire and the substrate at the second location.

[0007] Implementations may include any or all of the following features: The method further comprises advancing the bonding wire from a supply using a second motor of the wire bonding machine. The method further comprises coordinating operation of the first and second motors. Moving the wire bonding head from the first location to the second location comprises moving the wire bonding head vertically relative to the substrate. The method further comprises severing the bonding wire using a cutter of the wire bonding machine. [Brief description of the drawings]

[0008] [Figure 1] 1 illustrates an example of a wire bonding machine that can be used to form the wire bonds.

[0009] [Diagram 2] 1 shows an example of a wire bonding head.

[0010] [Diagram 3] 1 shows an example of the kinks that can occur in a ribbon with previous methods of wire bonding.

[0011] [Figure 4] 1 illustrates an example of actively feeding wire in wire bonding according to the present disclosure.

[0012] [Diagram 5] 1 illustrates an example of wire bonds where a loop is formed between the wire bonds.

[0013] [Figure 6] An example of the method is shown below.

[0014] Like reference numbers in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] This specification describes examples of systems and techniques that simplify and streamline the installation of bonding wires in battery modules by forming a bonding wire that continues from a cell onto an intermediate busbar and from there onto the next cell. This can be done between a pair of cells that are adjacently positioned on a busbar that has the shape of coplanar interleaved fingers, or between more than two cells. The wire bonding machine may not need to change direction (e.g., reverse or move sideways) as frequently as may be the case with most existing approaches, and therefore may accomplish its task of establishing a conductive bond more efficiently.

[0016] In the examples herein, it is referred to forming a bond between two or more conductive materials. As used herein, a bond can be formed by any technique that joins materials together so that an electric current can flow between them. To name just two examples, ultrasonic wire bonding and / or laser wire bonding can be used. The existence of a bond between materials indicates that the materials are electrically connected to each other, and is referred to herein as being bonded.

[0017] The examples herein refer to electrochemical cells. As used herein, an electrochemical cell is a device that generates electrical energy from a chemical reaction, or uses electrical energy to cause a chemical reaction, or both. An electrochemical cell may include an electrolyte and two electrodes to store energy and deliver it when in use. In some implementations, the electrochemical cell may be a rechargeable battery. For example, the electrochemical cell may be a lithium-ion battery. In some implementations, the electrochemical cell may act as a galvanic cell when discharged and as an electrolytic cell when charged. The electrochemical cell may have at least one terminal for each electrode. The terminal, or at least a portion thereof, may be located at one end of the electrolytic cell. For example, if the electrochemical cell is cylindrical in shape, one of the terminals may be provided at the center of the end of the cell, and the can that forms the cylinder may constitute the other terminal and thus may also be at the end. Other shapes of electrochemical cells may be used, including but not limited to prismatic shapes.

[0018] Examples herein refer to battery modules, which are individual components configured to hold and manage multiple electrochemical cells during charging, storage, and use. A battery module may be intended as the sole power source for one or more loads (e.g., electric motors), or more than one battery module of the same or different type may be used. Two or more battery modules can be implemented in a system separately or as part of a larger energy storage unit. For example, a battery pack can include two or more battery modules of the same or different types. The battery modules can include control circuits for managing the charging, storage, and / or use of electrical energy in the electrochemical cells, or the battery modules may be controlled by external components. For example, the battery management system can be implemented on one or more circuit boards (e.g., printed circuit boards).

[0019] Examples herein refer to bus bars, and a battery module may have at least one bus bar. The bus bar is conductive and is used to conduct electricity to the electrochemical cells during charging or from the cells during discharging. The bus bar is made of a conductive material (e.g., metal) and has suitable dimensions taking into account the properties and intended use of the electrochemical cells. In some implementations, the bus bar includes aluminum (e.g., an aluminum alloy). The bus bar may be planar (e.g., flat) or may have one or more curves, depending on the shape and intended use of the battery module. The bus bar may be configured to place the electrochemical cells in a series arrangement, a parallel arrangement, or a series and parallel arrangement.

[0020] Examples herein refer to a bonding wire (e.g., ribbon bonding wire, or ribbon wire, or other electrical conductor). As used herein, a bonding wire may have any number of different geometric shapes and may include one or more materials with respective electrical conductivity. For example, a bonding wire may be a single-layered bonding wire, or may be a multi-layered bonding wire having multiple layers, each with a respective electrical conductivity. In some implementations, a bonding wire may be a ribbon-like wire having a rectangular cross-section and one or more layers. The one or more layers may include one or more conductive materials, such as one or more metals and / or metal alloys. A bonding wire may include, but is not limited to, copper, aluminum, copper alloys, aluminum alloys, and / or combinations thereof. As used herein, a bonding wire being bonded to a surface (e.g., a conductive surface, an electrical contact surface, etc.) refers to the bonding wire being electrically and / or physically bonded to the surface, unless otherwise indicated.

[0021] Examples herein refer to top or bottom. These and similar expressions identify things or aspects relative to one another based on an explicit or arbitrary notion of perspective. That is, these terms are merely examples used for illustrative purposes and do not necessarily indicate the only possible positions, orientations, or the like.

[0022] FIG. 1 illustrates an example of a wire bonding machine 100 that can be used to form a wire bond. The wire bonding machine 100 can operate using a supply of bonding wire 102. The wire bonding machine 100 and / or the bonding wire 102 can be used with one or more other examples described elsewhere herein. The wire bonding machine 100 includes a wire guide 104. The wire guide 104 is used to guide (e.g., feed) the bonding wire 102 in a bonding operation. The wire guide 104 can be made of one or more materials, including, but not limited to, metal or synthetic materials. A supply 106 of the bonding wire 102 is seen passing through the wire guide 104. In some implementations, the supply 106 of the bonding wire 102 can be provided from a spool 108. For example, the spool 108 may be rotatably suspended relative to the wire bonding machine 100 so that the supply 106 of bonding wire 102 can be obtained continuously or intermittently, and so that the bonding wire 102 has a specific orientation relative to the electrochemical cell being bonded.

[0023] The wire bonding machine 100 may include a wedge 110. The wedge 110 may be used to bond the bonding wire 102 to an electrochemical cell (not shown). For example, the wedge 110 may be made of a metal.

[0024] The wire bonding machine 100 includes a cutter 112. The cutter 112 can be used to cut the bonding wire 102 before, during, or after bonding. For example, the cutter 112 can be made of metal.

[0025] The wire bonding machine 100 can include a motor 114. In some implementations, the motor 114 can be positioned relatively close to the spool 108 to facilitate unwinding the bonding wire 102 from the spool 108. For example, the motor 114 can be the first motorized component of the wire bonding machine 100 that engages the bonding wire 102 as it leaves the spool 108 (e.g., the bonding wire 102 can engage with one or more non-motorized wheels between the motor 114 and the spool 108). The motor 114 can be electrically powered and can include one or more wheels (e.g., two opposing wheels) that engage the bonding wire 102 to advance it in any direction. For example, the motor 114 can include at least two wheels that face each other across the bonding wire 102.

[0026] The wire bonding machine 100 can include a clamp 116. The clamp 116 can be actuated to engage and thereby immobilize or otherwise restrain the bonding wire 102 during some wire bonding operations. For example, the clamp 116 can stop the bonding wire 102 during bonding performed by the wedge 110 and / or during cutting by the cutter 112. The clamp 116 can be electrically actuated and can include one or more jaws (e.g., two opposing jaws) that engage the bonding wire 102 to limit its movement in either direction.

[0027] The wire bonding machine 100 can include a motor 118. In some implementations, the motor 118 can be positioned relatively close to the wire guide 104 to facilitate advancing the bonding wire 102 towards the wedge 110. For example, the motor 118 can be the last motor of the wire bonding machine 100 that advances the bonding wire 102 before the wire guide 104 (e.g., the clamp 116 can be positioned between the motor 118 and the wire guide 104). In some implementations, the clamp 116 is positioned adjacent to the wire guide 104 and the motor 118 is positioned upstream of the clamp 116. For example, the motor 118 can be positioned before the clamp 116 in the direction of advancement of the bonding wire 102 from the spool 108. The motor 118 can be positioned just before the clamp 116 in the direction of advancement of the bonding wire 102 from the spool 108.

[0028] The motor 118 can be electrically powered and can include one or more wheels (e.g., two opposing wheels) that engage and advance the bonding wire 102 in any direction. For example, the motor 118 can include at least two wheels that face each other across the bonding wire 102.

[0029] The wire bonding machine 100 can adjust the operation of the motors 114 and 118. In some implementations, the adjustments can seek to avoid stress or tension in the bonding wire 102. For example, the motor 114 can advance the bonding wire 102 from the spool 108 with some slack, and the motor 118 can then take advantage of this slack to feed the bonding wire 102 through the wire guide 104.

[0030] FIG. 2 illustrates an example of a wire bonding head 200. The wire bonding head 200 can be used with one or more other examples described elsewhere herein. For example, the wire bonding head 200 can be used as part of the wire bonding machine 100 of FIG. 1. The wire bonding head 200 includes a rotation stage 202 capable of controlling the orientation of the bond formation relative to a workpiece (not shown), which may include one or more substrates. The rotation stage 202 may include any mechanism for actuating the rotation of the wire bonding stage 204 relative to the workpiece. The wire bonding head 200 can be used for wire bond formation on substrates of any type of electric or electronic device, including, but not limited to, forming wire bonds between bus bars of a battery module and one or more terminals of individual cells. The mechanism of the rotation stage 202 may be actuated by gears, belt drives, or electromagnetic actuation, just to name a few.

[0031] The wire bonding stage 204 can include a motor 206 capable of driving at least one wheel 208. For example, the motor 206 can include at least two wheels 208 facing each other across a bonding wire 210 used by the wire bonding head 200 in wire bonding. The wheels 208 can engage and advance the bonding wire 210. The figure shows the bonding wire 210 emerging from the motor 206 and entering a wire guide 212 that is part of the wire bonding stage 204. The bonding wire 210 can then emerge from the opposite end of the wire guide 212 and can be acted upon using a wedge 214 that is also part of the wire bonding stage 204. In some implementations, a clamp (not shown) can be used. For example, the clamp is positioned in front of or behind the motor 206 in the advancement direction of the bonding wire 210.

[0032] FIG. 3 illustrates an example of a kink that may occur in a ribbon according to previous techniques for wire bonding, where a substrate 300 is shown generally as including a surface 302. A bonding wire 304 is used for wire bonding, where a wire bond 306 is formed at the end of the bonding wire 304. The bonding wire 304 emerges from a wire guide 308, which may be part of an apparatus (not shown) used in wire bonding. Once the wire bond 306 is formed, the wire guide 308 may be moved to a different location on the substrate 300. In doing so, the wire guide 308 may move perpendicular to the surface 302 of the substrate 300, as generally illustrated by arrow 310. Such movement (e.g., perpendicular movement) may cause a kink 312 to form in the bonding wire 304 adjacent to the wire bond 306. In some implementations, the kink 312 may form where the bonding wire 304 veers away from the surface 302. For example, kinks 312 can be a common failure point in previous approaches to wire bonding.

[0033] FIG. 4 illustrates an example of active wire feeding in wire bonding according to the present disclosure. Here, a substrate 400 is shown generally as including a surface 402. A bonding wire 404 is used for wire bonding. The wire bonding of this example can be performed using one or more of the other examples described elsewhere herein. Here, a wire bond 406 is formed at the end of the bonding wire 404. The bonding wire 404 emerges from a wire guide 408, which may be part of an apparatus (not shown) used in wire bonding. For example, any of the wire bonding heads and / or wire bonding machines described elsewhere herein may be used. Once the wire bond 406 is formed, the wire guide 408 may be moved to a different location on the substrate 400. In doing so, the wire guide 408 may move perpendicular to the surface 402 of the substrate 400, as generally illustrated by arrow 410. During such movement, the bonding wire 404 can be actively fed through the wire guide 408 using at least one motor. For example, active feeding can ensure that slack 412 is created in the bonding wire 404 between the wire guide 408 and the wire bond 406. Such active feeding of the bonding wire 404 can reduce or avoid kinking of the bonding wire 404. For example, failure points in bond formation can thereby be eliminated.

[0034] FIG. 5 illustrates an example of a wire bond where a loop is formed between the wire bonds. The wire bonding of this example can be performed using one or more of the other examples described elsewhere herein. Here, a substrate 500 is shown generally as including a surface 502. A bonding wire 504 is used for the wire bonding. The wire bonding of this example can be performed using one or more of the other examples described elsewhere herein. Here, a wire bond 506 is formed at an end of the bonding wire 504 at a location 508 on the surface 502. Any of the wire bonding heads and / or wire bonding machines described elsewhere herein can be used. After the wire bond 506 was formed, the wire guide was moved to a location 510 on the surface 502. A wire bond 512 was then formed at the location 510. The bonding wire 504 was actively fed during at least a portion of the bond formation process. Bonding wire 504 may be severed from the remainder of the bonding wire supply before, during, or after wire bond 512 is formed.

[0035] Locations 508 and 510 are spaced apart by a distance 514 on surface 502 of substrate 500. Additionally, active feeding of bonding wire 504 causes bonding wire 504 to have a length 516 that is greater than distance 514. Thus, bonding wire 504 has a bend 518 that can be characterized as a slack or loop in bonding wire 504 between wire bonds 506 and 512. That is, due to bend 518, bonding wire 504 does not simply extend in a straight line from wire bond 506 to wire bond 512. Bend 518 can reduce or avoid kinks in bonding wire 504. For example, a failure point in bond formation can be eliminated thereby.

[0036] Examples described herein illustrate that a wire bonding apparatus (e.g., wire bonding machine 100 of FIG. 1 ) can include a supply of bonding wire (e.g., spool 108 and bonding wire 102 of FIG. 1 ); a first motor (e.g., motor 114 of FIG. 1 ) for advancing the bonding wire from the supply; a wedge (e.g., wedge 110 of FIG. 1 ) for performing wire bonding by forming a first bond (e.g., wire bond 506 of FIG. 5 ) and a second bond (e.g., wire bond 512 of FIG. 5 ), the second bond being spaced a distance (e.g., distance 514) from the first bond; a wire guide 212 (e.g., wire guide in FIG. 2 ) adjacent the wedge for guiding the bonding wire toward the wedge; and a second motor (e.g., motor 118 of FIG. 1 or motor 206 of FIG. 2 ) for advancing the bonding wire into the wire guide. The second motor is configured to feed a length of the bonding wire (e.g., length 516 in FIG. 5 ) after formation of the first bond and before formation of the second bond, the length being greater than the distance between the first and second bonds (e.g., length 516 is greater than distance 514).

[0037] 6 illustrates one example of a method 600. Method 600 can be used with one or more other examples described elsewhere herein. More or less operations may be performed than shown. Two or more operations may be performed in a different order unless otherwise indicated.

[0038] At operation 602, the method 600 may include positioning a bond wire at a first location on a substrate. For example, bond wire 504 of FIG.

[0039] At operation 604, the method 600 may include forming a first wire bond between the bonding wire and the substrate at a first location using a wire bond head of a wire bonding machine. For example, wire bond 506 of FIG. 5 may be formed.

[0040] In operation 606, the method 600 may include moving the wire bonding head from the first location to a second location on the substrate after forming the first wire bond. For example, the wire bonding head 200 of FIG. 2 may be moved from location 508 to location 510 of FIG.

[0041] At operation 608, the method 600 can include actively feeding a length of bonding wire through the wire bond head using a first motor of the wire bonding machine while moving the wire bond head, the length being greater than the distance between the first and second locations. For example, bonding wire 504 of FIG. 5 can be fed a length 516.

[0042] At operation 610, the method 600 may include using a wire bonding head to form a second wire bond between the bond wire and the substrate at a second location. For example, wire bond 512 of FIG. 5 may be formed.

[0043] The terms "substantially" and "about" used throughout this specification are used to describe and report small variations, such as those caused by processing variations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Also, as used herein, indefinite articles such as "a" or "an" mean "at least one".

[0044] It should be understood that all combinations of the above concepts, and additional concepts discussed in more detail below (provided that such concepts are not mutually inconsistent), are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein.

[0045] Although multiple implementations have been described, it will be understood that various modifications may be made without departing from the spirit and scope of the specification.

[0046] Additionally, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Additionally, other processes may be provided or processes may be eliminated from the described flows, and other components may be added to or removed from the described systems. Accordingly, other implementations are within the scope of the following claims.

[0047] While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It should therefore be understood that the appended claims are intended to cover all such modifications and changes that fall within the scope of these implementations. It should be understood that they are presented merely as examples and not as limitations, and that various changes in form and details may be made. Any part of the apparatus and / or method described herein may be combined in any combination, except for mutually exclusive combinations. The implementations described herein may include various combinations and / or subcombinations of the functions, components, and / or features of the different implementations described. (Other possible items) (Item 1) Bonding wire supplies; a first motor for advancing the bonding wire from the supply; a wedge for performing wire bonding by forming a first bond and a second bond, the second bond being spaced a distance from the first bond; a wire guide adjacent the wedge for guiding the bonding wire toward the wedge; and a second motor for advancing the bonding wire into the wire guide, the second motor configured to feed a length of the bonding wire after formation of the first bond and before formation of the second bond, the length being greater than the distance between the first bond and the second bond; A wire bonding apparatus comprising: (Item 2) 2. The wire bonding apparatus of claim 1, further comprising a clamp for the bonding wire. (Item 3) 3. The wire bonding apparatus of claim 2, wherein the clamp is positioned adjacent to the wire guide and the second motor is positioned in front of the clamp in a direction in which the bonding wire advances from the supply. (Item 4) 4. The wire bonding apparatus of claim 3, wherein the second motor is positioned immediately before the clamp in a direction in which the bonding wire advances from the supply. (Item 5) 2. The wire bonding apparatus of claim 1, wherein the supply of bonding wire comprises a spool. (Item 6) 6. The wire bonding apparatus according to any one of claims 1 to 5, wherein the second motor has at least two wheels that face each other across the bonding wire. (Item 7) 7. The wire bonding apparatus of any one of claims 1 to 6, further comprising a cutter for cutting the bonding wire. (Item 8) Positioning a bonding wire at a first location on the substrate; forming a first wire bond between the bonding wire and the substrate at the first location using a wire bonding head of a wire bonding machine; moving the wire bonding head from the first location to a second location on the substrate after forming the first wire bond; actively feeding a length of the bonding wire through the wire bond head using a first motor of the wire bonding machine while moving the wire bond head, the length being greater than a distance between the first location and the second location; and forming a second wire bond between the bonding wire and the substrate at the second location using a wire bonding head. A method for providing the above. (Item 9) 9. The method of claim 8, further comprising the step of advancing the bonding wire from a supply using a second motor of the wire bonding machine. (Item 10) 10. The method of claim 9, further comprising coordinating operation of the first motor and the second motor. (Item 11) 11. The method of any one of claims 8 to 10, wherein moving the wire bonding head from the first location to the second location comprises moving the wire bonding head vertically relative to the substrate. (Item 12) 12. The method of any one of claims 8 to 11, further comprising cutting the bonding wire using a cutter of the wire bonding machine.

Claims

1. a supply of bonding wire; a first motor for advancing the bonding wire from the supply; a wedge for performing wire bonding by forming a first bond and a second bond, the second bond being spaced a distance from the first bond; a wire guide adjacent the wedge for guiding the bonding wire toward the wedge; and a second motor for advancing the bonding wire into the wire guide, the second motor configured to feed a length of the bonding wire after formation of the first bond and before formation of the second bond, the length being greater than the distance between the first bond and the second bond; A wire bonding apparatus comprising:

2. The wire bonding apparatus of claim 1 further comprising a clamp for the bonding wire.

3. 3. The wire bonding apparatus of claim 2, wherein the clamp is positioned adjacent to the wire guide and the second motor is positioned in front of the clamp in a direction of advancement of the bonding wire from the supply.

4. 4. The wire bonding apparatus of claim 3, wherein the second motor is positioned immediately before the clamp in a direction of advancement of the bonding wire from the supply.

5. The wire bonding apparatus of claim 1 , wherein the supply of bonding wire comprises a spool.

6. The wire bonding apparatus according to claim 1 , wherein the second motor has at least two wheels that face each other across the bonding wire.

7. The wire bonding apparatus according to claim 1 , further comprising a cutter for cutting the bonding wire.

8. Positioning a bonding wire at a first location on a substrate; forming a first wire bond between the bonding wire and the substrate at the first location using a wire bonding head of a wire bonding machine; moving the wire bonding head from the first location to a second location on the substrate after forming the first wire bond; actively feeding a length of the bonding wire through the wire bond head using a first motor of the wire bonding machine while moving the wire bond head, the length being greater than a distance between the first location and the second location; and forming a second wire bond between the bonding wire and the substrate at the second location using a wire bonding head. A method for providing the above.

9. 9. The method of claim 8, further comprising the step of advancing the bonding wire from a supply using a second motor of the wire bonding machine.

10. The method of claim 9 , further comprising coordinating operation of the first motor and the second motor.

11. 11. The method of claim 8, wherein moving the wire bonding head from the first location to the second location comprises moving the wire bonding head vertically relative to the substrate.

12. 11. The method of claim 8, further comprising severing the bonding wire using a cutter of the wire bonding machine.

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