Methods of operating a wire bonding machine, including methods of monitoring bond force accuracy in a wire bonding machine, and related methods

Abstract

A method of operating a wire bonding apparatus is provided, the method including: (a) operating a wire bonding apparatus during at least one of (1) an automatic wire bonding operation and (2) a dry cycle wire bonding operation, wherein a bonding force is applied during operation of the wire bonding apparatus; and (b) monitoring accuracy of the bonding force of the wire bonding apparatus during the at least one of (1) the automatic wire bonding operation and (2) the dry cycle wire bonding operation.

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 110,012, filed November 5, 2020, the contents of which are incorporated herein by reference.

[0002] The present invention relates to wire bonding operations, and more particularly to a technique for monitoring the accuracy of bonding force in a wire bonding apparatus. [Background technology]

[0003] In the fabrication and packaging of semiconductor devices, wire bonding remains the primary method for providing electrical interconnection between two locations within a package (e.g., between a die pad on a semiconductor die and a lead on a lead frame). Specifically, a wire bonder (also called a wire bonding machine) is used to form a wire loop between the respective locations to be electrically interconnected. The methods for forming the wire loop primarily include ball bonding and wedge bonding. Various types of bonding energy, including, for example, ultrasonic energy, thermosonic energy, thermocompression energy, etc., may be used to form a bond between (a) the end of the wire loop and (b) the bond site (e.g., die pad, lead, etc.). Wire bonding machines (e.g., stud bumping machines) are also used to form conductive bumps from portions of wire.

[0004] Such wire bonding machines typically include a bond head assembly (i.e., bond head) that carries a wire bonding tool (e.g., a capillary tool) that contacts a workpiece during the wire bonding operation. In connection with most wire bonding operations, a bonding force is applied to the wire bonding tool. To form a consistent (acceptable) wire bond, it is important that the bonding force applied during wire bonding is accurate. However, sometimes the applied force differs from the intended (e.g., programmed) bonding force. For example, the bonding force may change over time due to conditions such as environmental factors and machine uptime.

[0005] It would therefore be desirable to provide improved techniques for monitoring and / or controlling the bonding force in a wire bonding apparatus. The prior art documents relevant to the invention of this application are as follows (including documents cited in the international phase after the international filing date and documents cited when the application entered the national phase in other countries). (Prior art document) (Patent document) (Patent Document 1) U.S. Patent No. 4,373,653 (Patent Document 2) U.S. Patent Application Publication No. 2010 / 0108744 (Patent Document 3) U.S. Patent Application Publication No. 2017 / 0125311 (Patent Document 4) JP 2012-074699 A (Patent Document 5) U.S. Patent No. 5,230,458 Summary of the Invention

[0006] According to an exemplary embodiment of the present invention, a method of operating a wire bonding apparatus is provided, the method including: (a) operating a wire bonding apparatus during at least one of (1) an automatic wire bonding operation and (2) a dry cycle wire bonding operation, wherein a bonding force is applied during the operation of the wire bonding apparatus; and (b) monitoring accuracy of the bonding force of the wire bonding apparatus during the at least one of (1) the automatic wire bonding operation and (2) the dry cycle wire bonding operation.

[0007] According to another exemplary embodiment of the present invention, a method of operating a wire bonding apparatus is provided that includes incrementally adjusting a bonding force applied to a bond head assembly while sensing a z-height position of a portion of the bond head assembly, and determining a desired bonding force at which the incremental adjustment does not result in a change in the z-height position of the bond head assembly.

[0008] According to another exemplary embodiment of the present invention, a method of operating a wire bonding apparatus is provided that includes incrementally adjusting a bonding force applied to a bond head assembly while detecting a z-height position of a portion of the bond head assembly, and determining a desired bonding force that results in a peak z-height position of the bond head assembly from the incremental adjustments.

[0009] According to yet another exemplary embodiment of the present invention, there is provided a method of operating a wire bonding apparatus, the method including: gradually decreasing a bonding force applied to a bond head assembly while detecting a z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment; and detecting a bonding force value when the z-height position changes from the initial height by the predetermined height adjustment.

[0010] According to yet another exemplary embodiment of the present invention, there is provided a method of operating a wire bonding apparatus, the method including: gradually increasing a bonding force applied to a bond head assembly while detecting a z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment; and detecting a bonding force value when the z-height position changes from the initial height by the predetermined height adjustment.

[0011] The methods of the present invention may also be embodied as an apparatus (e.g., as part of the intelligence of a wire bonding apparatus) or as computer program instructions on a computer-readable medium (e.g., a computer-readable medium containing a wire bonding program for use in connection with a wire bonding apparatus). [Brief explanation of the drawings]

[0012] The invention will be best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of said drawings are not to scale. On the contrary, the dimensions of the various features have been arbitrarily increased or reduced for clarity. Included in said drawings are the following figures: [Figure 1] 1A-1C are a series of block diagram side views of a wire bonding apparatus illustrating a method of operation of the wire bonding apparatus according to an exemplary embodiment of the present invention. [Figure 2] 2A-2C are another series of block diagram side views of a wire bonding apparatus illustrating a method of operation of the wire bonding apparatus in accordance with an exemplary embodiment of the present invention. [Figure 3] 3A-3F are yet another series of block diagram side views of a wire bonding apparatus illustrating a method of operating a wire bonding apparatus according to an exemplary embodiment of the present invention. [Figure 4]FIG. 4 is a timing diagram illustrating the z-height position of a portion of a bond head assembly and the bonding force applied by the bond head assembly versus time in accordance with an exemplary embodiment of the present invention. [Figure 5-8] 5-8 are flow diagrams illustrating methods of operating a wire bonding apparatus according to various exemplary embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] According to various exemplary embodiments of the present invention, methods are provided for operating a wire bonding apparatus, such as automatically verifying bonding force (sometimes referred to as bond force) and monitoring bonding force in real time in a wire bonding apparatus. In certain embodiments of the present invention, the methods may include an auto-mode bonding force verification process and / or a closed-loop bonding force adjustment process (e.g., including offset adjustment of the bonding force).

[0014] Accordingly, aspects of the present invention relate to monitoring and / or automatically correcting / adjusting the bonding force applied by a wire bonding apparatus to achieve desired wire bonding performance. For example, according to aspects of the present invention, the bonding force (and / or the accuracy of the bonding force) may be monitored in an automatic wire bonding mode (and / or a dry cycle bonding mode), and if the accuracy of the monitored bonding force is not within an acceptable range (e.g., the monitored bonding force shifts for some reason), a response may be provided. For example, the response may be (1) providing an alarm, warning, or error message to an apparatus operator, (2) stopping operation of the wire bonding apparatus, (3) automatically adjusting the bonding force of the wire bonding apparatus (e.g., closed-loop force offset adjustment), etc.

[0015] According to an exemplary embodiment of the present invention, a method for verifying the bonding force of the apparatus in an automatic mode is provided. Such a method may include applying multiple levels of bonding force and monitoring the bond head position response. For example, a starting force (e.g., a pre-verified force Fpv, which may or may not be zero grams of force) may be gradually decreased in small increments until the wire bonding apparatus moves to a set height (e.g., ha), and then increased until the wire bonding apparatus moves back to a starting point (e.g., hinit). This force verification may be performed in both dry cycle and automatic modes. The two force values ​​(and / or additional force values ​​within the scope of the present invention, such as Fb) (e.g., the force value corresponding to the set height ha and the force value corresponding to the return to the starting point hinit) are recorded. If the force values ​​do not meet expectations (e.g., are not within an acceptable range of the expected force values), a response may be provided (e.g., providing an alarm, warning, or error message to an apparatus operator, stopping operation of the wire bonding apparatus, or automatically adjusting the bonding force of the wire bonding apparatus to an acceptable level).

[0016] The present invention offers significant advantages over past practices. Existing methods of bonding force calibration involve an operator performing the calibration offline (not in an automatic mode). Such calibration tends to be time consuming and requires the removal of certain hardware components (e.g., a flow head for a reducing gas) and the installation of calibration weights. Aspects of the present invention provide force verification in an automatic mode with minimal (or no) time penalty and may also be used to provide closed-loop bonding force adjustment.

[0017] Aspects of the present invention relate to monitoring the bonding force accuracy of a wire bonding apparatus during at least one of (1) an automatic wire bonding operation and (2) a dry cycle wire bonding operation. Exemplary techniques for monitoring such bonding force accuracy are disclosed herein. However, other techniques for achieving such monitoring (during at least one of an automatic wire bonding operation and a dry cycle wire bonding operation) are contemplated within the scope of the present invention.

[0018] As used herein, the term “zero gram force” refers to an example of an applied bonding force where incremental adjustments of the force (e.g., increasing or decreasing the bonding force) do not result in a change in the z-height position of the bond head assembly. The term “zero gram force” can also be used to refer to an applied bonding force that results in a peak height (either a high peak height or a low peak height) of a portion of the bond head assembly (e.g., a force Fb that results in a height hb and a force Fb that results in a height hd, both of which are described in connection with FIG. 4). In either case, such a “zero gram force” value may be determined from a single value (e.g., see Fb from FIG. 4, Fd from FIG. 4, etc.). Furthermore, a “zero gram force” or a determined “desired” force within the scope of the present invention can utilize multiple measurements (e.g., see Fb from FIG. 4, Fd from FIG. 4, etc.) to determine a single force value. For example, a single force value may be determined by averaging (or otherwise mathematically manipulating) multiple measurements from a single cycle (such as FIG. 4) or multiple cycles.

[0019] Aspects of the invention relate to detecting the applied bonding force at different height positions of a bond head assembly of a wire bonding apparatus. For example, force values ​​may be detected as the z-height position changes from one height to another (e.g., from an initial height according to the predetermined height adjustment). In other aspects of the invention, the height position of a bond head assembly of a wire bonding apparatus is detected at different values ​​of applied bonding force. Such bonding force and / or height position information may be used to monitor the accuracy of the bonding force.

[0020] The present invention is described largely in connection with, but not limited to, a force control mode of a wire bonding apparatus. For example, a position control mode may also be utilized. In connection with such a position control mode, characteristics of the z-axis drive force (corresponding to the bonding force) may be determined while substantially maintaining a predetermined z-axis position to monitor the accuracy of the bonding force. Such characteristics may be, for example, electrical characteristics of the z-axis motor, the current through the z-axis motor that provides the drive force, etc.

[0021] The same reference numerals refer to the same elements throughout the various drawings provided herein, and therefore, the description of certain elements may be omitted in relation to some drawings.

[0022] Referring now to the drawings, FIGS. 1A-1C illustrate a wire bonding apparatus 100. The wire bonding apparatus 100 includes a support structure 102 (e.g., a heat block, anvil, etc.) for supporting a workpiece 104 (e.g., a semiconductor device such as a lead frame holding one or more semiconductor dies) during a wire bonding operation. In FIG. 1A, the wire bonding apparatus 100 also includes a wire bonding tool 108 (e.g., a capillary wire bonding tool, a wedge bonding tool, etc.) for bonding a wire portion to the workpiece 104. As will be appreciated by those skilled in the art, the wire bonding tool 108 (carried by a bond head assembly 110) is movable along multiple axes of the wire bonding apparatus 100 to perform the wire bonding operation. For example, the wire bonding tool 108 can be moved along an X-axis and a Y-axis through movement of the bond head assembly 110. A linkage 110a is provided as part of the bond head assembly 110. Linkage 110a, together with bond head assembly 110, is configured to move along the z-axis of wire bonding apparatus 100 and is driven along the z-axis by z-axis motor 116 (controlled by computer 114 of wire bonding apparatus 100). A z-axis position detector 112 (e.g., a z-axis encoder) is provided to detect the z-axis position of linkage 110a (and thus the relative z-axis position of wire bonding tool 108) and provide data corresponding to this z-axis position to computer 114 of wire bonding apparatus 100 (e.g., in real time). Thus, computer 114 has information related to the z-axis position of wire bonding tool 108 throughout its movement. In a force control mode, z-axis motor 116 may be used to apply a bonding force in connection with a wire bonding operation.

[0023] With specific reference to FIG. 1A, the free air ball 106 is seated on the working tip 108a (contact portion) of the wire bonding tool 108. In some embodiments, the free air ball 106 is not required within the scope of the present invention (e.g., the present method may be performed without a wire portion on the working tip 108a). The initial height shown in FIG. 1A is h init (see, e.g., the left side of the timing diagram in FIG. 4, discussed below in conjunction with FIG. 3A). While h init is shown with respect to the working tip 108a of the wire bonding tool 108 (adjacent the free air ball 106), this is a relative height and may be illustrated with respect to any portion of the bond head assembly 110 that moves along the z-axis. At this stage, while detecting the z-height position of a portion of the bond head assembly 110 (e.g., via the z-axis motor 116), the bonding force applied to the bond head assembly 110 is gradually decreased until the z-height position changes from h init by a predetermined height adjustment (in FIG. 1B, until it reaches a height ha) (see, e.g., ha in the timing diagram of FIG. 4 described below in conjunction with FIG. 3B). During this decrease in bonding force, the bonding force value is detected when the z-height position changes from h init by the predetermined height adjustment shown in FIG. 1B. Next, while detecting the z-height position of a portion of the bond head assembly 110 (using the z-axis position detector 112), the bonding force applied to the bond head assembly 110 is gradually increased until the z-height position returns to h init as shown in FIG. 1C (see, e.g., h init caused by F in the timing diagram of FIG. 4 described below in conjunction with FIG. 3D). During this increase in bonding force, the bonding force value is detected as the z-height position changes back to h init as shown in FIG. 1C. These detected bonding force values ​​may be used to monitor the accuracy of the bonding force (e.g., including the accuracy of the zero gram force) (e.g., the accuracy of the applied bonding force compared to the intended (e.g., programmed) bonding force). Of course, variations and additional process steps may be included in this exemplary process.

[0024] The process illustrated in FIGS. 1A-1C is just one technique (and / or method of operating a wire bonding apparatus) for monitoring the accuracy of the bonding force. FIGS. 2A-2C show another non-limiting example. With particular reference to FIG. 2A, the initial height shown is h init. While h init is shown with respect to the working tip 108a of the wire bonding tool 108 (adjacent the free air ball 106), it is a relative height and may be illustrated with respect to any portion of the bond head assembly 110 moving along the z-axis. At this stage, while detecting the z-height position of a portion of the bond head assembly 110 (using the z-axis position detector 112), the bonding force applied to the bond head assembly 110 (e.g., via the z-axis motor 116) is gradually increased until the z-height position changes from h init by a predetermined height adjustment (in FIG. 2B, to height ha). During this incremental increase in bonding force, a bonding force value is detected as the z-height position changes from h init due to the predetermined height adjustment shown in FIG. 2B. Then, while detecting the z-height position of the portion of the bond head assembly 110 (using z-axis position detector 112), the bonding force applied to the bond head assembly 110 is incrementally decreased until the z-height position returns to h init, as shown in FIG. 2C. During this incremental decrease in bonding force, the bonding force value is detected as the z-height position changes back to h init, as shown in FIG. 2C. Using these detected bonding force values, the accuracy of the bonding force (e.g., including the accuracy of the zero gram force) may be monitored (e.g., the accuracy of the applied bonding force compared to the intended (e.g., programmed) bonding force).

[0025] Figures 3A-3F illustrate another non-limiting example (and / or method of operating a wire bonding apparatus) for monitoring the accuracy of the bonding force. Figure 4 is a timing diagram illustrating the z-height position of a portion of the bond head assembly and the bonding force applied by the bond head assembly versus time. The timing diagram in Figure 4 is consistent with the process steps shown in Figures 3A-3F, described below.

[0026] With specific reference to FIG. 3A, the wire bonding apparatus 100 is shown with the free air ball 106 at position h init. The applied force at this point can be described as a previously verified zero-gram force (see "Fpv" in FIG. 4). In FIG. 3B, the wire bonding tool 108 moves upward (i.e., in the +Z direction) to position ha as the applied force to the wire bonding tool 108 decreases (this is shown in FIG. 4 as the applied force changes from Fpv to Fa) (see FIG. 4, where force Fa is applied, at which point the applied force begins to increase). In FIG. 3C, the wire bonding tool 108 continues to move upward to position hb (this is shown in FIG. 4 between points ha and hb) despite the increasing force, e.g., due to momentum of the bond head assembly 110. A zero-gram force (e.g., force Fb) may be determined / monitored at this point (i.e., at height hb, where the height is a local maximum). Thus, with reference to FIG. 3C, zero gram force may be determined relative to the applied bonding force that results in the peak height hb (i.e., the force Fb that results in the height hb, as described with reference to FIG. 4).

[0027] In FIG. 3D, the wire bonding tool 108 is returned to an initial position h init when the applied force is at its peak, Fc (this is illustrated in FIG. 4 between points Fb and Fc). In FIG. 3E, the wire bonding tool 108 is moved to a position hd when the applied force is decreasing (this is illustrated in FIG. 4 between points Fc and Fd). Another zero-gram force (e.g., Fd) may be determined / monitored at this point (i.e., hd where the height is at a local minimum). That is, with reference to FIG. 3E, the zero-gram force may be determined relative to the applied bonding force that results in the peak height hd (i.e., the force Fd that results in height hd as described with reference to FIG. 4).

[0028] In FIG. 3F, the wire bonding tool 108 returns to position hinit (which is shown in FIG. 4 between points Fd and Fe) as the applied force continues to decrease.

[0029] While the timing diagram shown in FIG. 4 is for a short period of time (e.g., one cycle), it is understood that this process shown in FIG. 4 (or any portion thereof claimed herein) may be repeated for multiple cycles until a desired result occurs (e.g., a desired bonding force is determined, a stable bonding force value is determined, an accurate zero gram force value is determined, the accuracy of the bonding force is determined, etc.).

[0030] 5-8 are flow diagrams illustrating methods of operating a wire bonding apparatus (and related methods) according to various exemplary embodiments of the present invention. As will be understood by those skilled in the art, certain steps included in the flow diagrams may be omitted, certain additional steps may be added, and the order of the steps may be changed from the order shown.

[0031] 5, a method of operating a wire bonding apparatus is illustrated. At step 500, a wire bonding apparatus is operated during at least one of (1) an automatic wire bonding operation and (2) a dry cycle wire bonding operation, and a bonding force is applied during operation of the wire bonding apparatus. At step 502, accuracy of the bonding force of the wire bonding apparatus is monitored during at least one of (1) the automatic wire bonding operation and (2) the dry cycle wire bonding operation. For example, at step 502, accuracy of the applied bonding force compared to the intended (e.g., programmed) bonding force may be monitored.

[0032] For example, step 502 may occur during a force control mode (or position control mode) of operation of the wire bonding apparatus. During step 502, the force applied to the bond head assembly of the wire bonding apparatus may be incrementally adjusted (e.g., incrementally increase force, incrementally decrease force, both incrementally increase and decrease force, etc.) while detecting the z-height position of a portion of the bond head assembly.

[0033] Additional aspects of the present invention may also occur during step 502. For example, a precise zero gram force may be determined during step 502. For example, in connection with step 502, a desired force may be determined such that incremental adjustments from step 500 do not result in a change in the z-height position of the bond head assembly. Stated differently, a desired force may be determined at an applied force (e.g., force Fb resulting in height hb, force Fd resulting in height hd, both as described in connection with FIG. 4 ) at which incremental adjustments from step 500 result in a peak z-height position of the bond head assembly.

[0034] Additionally, the wire bonding tool may be positioned above and not in contact with a workpiece on the wire bonding apparatus during step 502. Alternatively, the wire bonding tool may be in contact with a workpiece on the wire bonding apparatus during step 502.

[0035] In optional step 504, if the accuracy of the bonding force monitored during step 502 is not within an acceptable range, a response is provided. For example, the response may include at least one of the following steps: (a) providing an alarm to a machine operator, (b) providing a warning to the machine operator, (c) providing an error message to the machine operator, (d) stopping operation of the wire bonding apparatus, or (e) automatically adjusting the bonding force of the wire bonding apparatus.

[0036] Referring now to FIG. 6, another method of operating a wire bonding apparatus is illustrated. In step 600, a bonding force applied to a bond head assembly is incrementally adjusted (e.g., incrementally increasing the bonding force, incrementally decreasing the bonding force, both incrementally increasing and decreasing the bonding force, etc.) while detecting a z-height position of a portion of the bond head assembly. In step 602, a desired bonding force is determined where the incremental adjustment from step 600 does not result in a change in the z-height position of the bond head assembly. For example, the desired bonding force may be 0 grams-force. An alternative to step 602 is to determine the desired force at an applied force where the incremental adjustment from step 600 results in a peak z-height position of the bond head assembly (e.g., a force Fb resulting in a height hb, a force Fb resulting in a height hd, both as described in connection with FIG. 4).

[0037] As will be appreciated by those skilled in the art, steps 600 and 602 may be repeated for multiple cycles until the desired bonding force is determined to a stable value by the wire bonding machine at step 602. Additionally, steps 600 and 602 may occur during a force control mode (or position control mode) of operation of the wire bonding machine.

[0038] Referring now to FIG. 7, yet another method of operating a wire bonding apparatus is illustrated. In step 700, while detecting a z-height position of a portion of the bond head assembly, a bonding force applied to the bond head assembly is gradually decreased until the z-height position changes from an initial height (e.g., h init) by a predetermined height adjustment (e.g., see height adjustment to height ha in FIGS. 1B and 3B). In step 702, a bonding force value (e.g., Fa in FIG. 4 with reference to ha in FIG. 1B or 3B) associated with the change in z-height position from the initial height due to the predetermined height adjustment is detected. In optional step 704, after step 702, while detecting the z-height position of the portion of the bond head assembly, the bonding force applied to the bond head assembly is gradually increased until the z-height position returns to the initial height (e.g., see back to h init in FIGS. 1C and 3D, corresponding to bonding force F from FIG. 4).

[0039] After step 700, the z-height position can continue to change until a peak height position (eg, see height hb from FIG. 3C, which corresponds to bonding force value Fb) is reached.

[0040] Additionally, steps 700 and 702 may occur during a force control mode (or position control mode) of operation of the wire bonding machine.

[0041] Referring now to FIG. 8, yet another method of operating a wire bonding apparatus is illustrated. In step 800, while detecting a z-height position of a portion of the bond head assembly, the bonding force applied to the bond head assembly is gradually increased until the z-height position changes from an initial height (e.g., h init) by a predetermined height adjustment (e.g., see height adjustment to height ha in FIG. 2B). In step 802, a bonding force value (e.g., the bonding force corresponding to height ha in FIG. 2B) is detected in response to the z-height position changing from the initial height by the predetermined height adjustment. In optional step 804, after step 802, while detecting the z-height position of the portion of the bond head assembly, the bonding force applied to the bond head assembly is gradually decreased until the z-height position returns to the initial height (e.g., see return to h init in FIG. 2C). In connection with this step 804, a bonding force value may be detected as the z-height position returns to the initial height.

[0042] 8, after step 800, the z-height position may continue to change until a peak height position is reached, at which the bonding force value may be detected.

[0043] Additionally, steps 800 and 802 may occur during a force control mode (or position control mode) of operation of the wire bonding machine.

[0044] 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. Rather, various changes in details may be made within the scope of the claims and their equivalents without departing from the invention.

Claims

1. 1. A method of operating a wire bonding apparatus, comprising: (a) operating a wire bonding apparatus during at least one of (1) an automatic wire bonding operation and (2) a dry cycle wire bonding operation, wherein a bonding force is applied during said operation of the wire bonding apparatus; (b) monitoring accuracy of the bonding force of the wire bonding apparatus during at least one of (1) the automatic wire bonding operation and (2) the dry cycle wire bonding operation, wherein step (b) includes incrementally adjusting a bonding force applied to the bond head assembly of the wire bonding apparatus while detecting a z-height position of a portion of the bond head assembly; A method comprising:

2. The method of claim 1 further comprising: providing a response if the accuracy of the bonding force monitored during step (b) is not within an acceptable range.

3. 3. The method of claim 2, wherein the response includes at least one of the following steps: (a) providing an alarm to an equipment operator; (b) providing a warning to the equipment operator; (c) providing an error message to the equipment operator; (d) stopping operation of the wire bonding equipment; and (e) automatically adjusting the bonding force of the wire bonding equipment.

4. 2. The method of claim 1, wherein step (b) occurs during a force control mode of operation of the wire bonding machine.

5. 10. The method of claim 1, wherein in connection with step (b), a zero gram force is determined.

6. 2. The method of claim 1, wherein, in connection with step (b), the desired force is determined such that incremental adjustments from step (b) result in no change in the z-height position of the bond head assembly.

7. 2. The method of claim 1, wherein, in connection with step (b), the desired force is determined such that the incremental adjustment from step (b) results in a peak z-height position of the bond head assembly.

8. 2. The method of claim 1, wherein step (b) occurs during a force control mode of operation of the wire bonding machine.

9. 2. The method of claim 1, wherein step (b) includes gradually reducing the bonding force applied to the bond head assembly of the wire bonding apparatus while detecting the z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment.

10. 10. The method of claim 9, wherein in step (b), a force value is detected as the z-height position changes from the initial height by the predetermined height adjustment.

11. 10. The method of claim 9, wherein the step of tapering the force is repeated for a plurality of cycles, each of the plurality of cycles being used in conjunction with the step of monitoring the accuracy of the bonding force.

12. 2. The method of claim 1, wherein step (b) includes gradually increasing the bonding force applied to the bond head assembly of the wire bonding apparatus while detecting the z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment.

13. 13. The method of claim 12, wherein in step (b), a force value is detected as the z-height position changes from the initial height by the predetermined height adjustment.

14. 13. The method of claim 12, wherein the step of gradually increasing the force is repeated for a plurality of cycles, each of the plurality of cycles being used in conjunction with the step of monitoring the accuracy of the bonding force.

15. 2. The method of claim 1, wherein step (b) occurs during a position control mode of the wire bonding machine.

16. 16. The method of claim 15, wherein in connection with step (b), a precise zero gram force is determined.

17. 16. The method of claim 15, wherein a characteristic of the z-axis drive force is determined while substantially maintaining a predetermined z-axis position to monitor accuracy of the bonding force.

18. 20. The method of claim 17, wherein the characteristic is an electrical characteristic of a z-axis motor.

19. 20. The method of claim 18, wherein the characteristic is a current in a z-axis motor that provides the driving force.

20. 10. The method of claim 1, wherein step (b) occurs with a wire bonding tool positioned above a workpiece on the wire bonding apparatus but not in contact with the workpiece.

21. 10. The method of claim 1, wherein step (b) occurs with a wire bonding tool in contact with a workpiece on the wire bonding machine.

22. 1. A method of operating a wire bonding apparatus, comprising: (a) incrementally adjusting a bonding force applied to a bond head assembly while sensing a z-height position of a portion of the bond head assembly; (b) determining a desired bonding force such that incremental adjustments from step (a) do not result in a change in the z-height position of the bond head assembly; A method comprising:

23. 23. The method of claim 22, wherein the desired bonding force is zero gram force.

24. 23. The method of claim 22, wherein step (b) includes at least one of gradually increasing the bonding force and gradually decreasing the bonding force.

25. 23. The method of claim 22, wherein step (a) includes both gradually increasing the bonding force and gradually decreasing the bonding force.

26. 23. The method of claim 22, wherein steps (a) and (b) are repeated multiple cycles until the desired bonding force is determined to a stable value by a wire bonding machine.

27. 23. The method of claim 22, wherein steps (a) and (b) occur during a force control mode of operation of the wire bonding machine.

28. 23. The method of claim 22, wherein the desired bonding force results in a peak z-height position of the bond head assembly.

29. 1. A method of operating a wire bonding apparatus, comprising: (a) incrementally adjusting a bonding force applied to a bond head assembly while sensing a z-height position of a portion of the bond head assembly; (b) determining a desired bonding force where the incremental adjustment from step (a) results in a peak z-height position of said bond head assembly; A method comprising:

30. 30. The method of claim 29, wherein the desired bonding force is zero gram force.

31. 30. The method of claim 29, wherein step (a) includes at least one of gradually increasing the bonding force and gradually decreasing the bonding force.

32. 30. The method of claim 29, wherein step (a) includes both gradually increasing the bonding force and gradually decreasing the bonding force.

33. 30. The method of claim 29, wherein steps (a) and (b) are repeated multiple cycles until the desired bonding force is determined at a stable value by a wire bonding machine.

34. 30. The method of claim 29, wherein steps (a) and (b) occur during a force control mode of operation of the wire bonding machine.

35. 1. A method of operating a wire bonding apparatus, comprising: (a) gradually decreasing a bonding force applied to the bond head assembly while detecting a z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment; (b) detecting a bonding force value when the z-height position changes from the initial height due to the predetermined height adjustment; A method comprising:

36. 36. The method of claim 35, wherein the bonding force value is Fa.

37. 36. The method of claim 35, after step (b), the method further comprises the step of gradually increasing the bonding force applied to the bond head assembly while detecting the z-height position of a portion of the bond head assembly until the z-height position returns to the initial height.

38. 38. The method of claim 37, wherein the bonding force value when the z-height position returns to the initial height is detected as Fc.

39. 36. The method of claim 35, wherein after step (a), the z-height position continues to change until a peak height position is reached.

40. 40. The method of claim 39, wherein the bonding force at the z height position where the peak height position is reached is detected as Fb.

41. 36. The method of claim 35, wherein steps (a) and (b) occur during a force control mode of operation of the wire bonding machine.

42. 1. A method of operating a wire bonding apparatus, comprising: (a) gradually increasing a bonding force applied to the bond head assembly while detecting a z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment; (b) detecting a bonding force value when the z-height position changes from the initial height due to the predetermined height adjustment, wherein after step (b), the method includes gradually decreasing the bonding force applied to the bond head assembly while detecting the z-height position of a portion of the bond head assembly until the z-height position returns to the initial height; A method comprising:

43. 43. The method of claim 42, wherein the bonding force value is detected as the z-height position returns to the initial height.

44. 43. The method of claim 42, wherein after step (a), the z-height position continues to change until a peak height position is reached.

45. 45. The method of claim 44, wherein the bonding force is detected at the z-height position where the peak height position is reached.

46. 43. The method of claim 42, wherein steps (a) and (b) occur during a force control mode of operation of the wire bonding machine.

47. A method of operating a wire bonding apparatus, comprising: (a) operating a wire bonding apparatus during at least one of (1) an automatic wire bonding operation and (2) a dry cycle wire bonding operation, wherein a bonding force is applied during said operation of the wire bonding apparatus; (b) monitoring the bonding force accuracy of the wire bonding machine during at least one of (1) the automatic wire bonding operation and (2) the dry cycle wire bonding operation, wherein step (b) occurs during a position control mode of the wire bonding machine; A method comprising:

48. The method of claim 47, further comprising: providing a response if the accuracy of the bonding force monitored during step (b) is not within an acceptable range.

49. The method of claim 48, wherein the response includes at least one of the following steps: (a) providing an alarm to an equipment operator; (b) providing a warning to the equipment operator; (c) providing an error message to the equipment operator; (d) stopping operation of the wire bonding equipment; and (e) automatically adjusting the bonding force of the wire bonding equipment.

50. The method of claim 47, wherein step (b) occurs during a force control mode of operation of the wire bonding machine.

51. A method as described in claim 47, wherein step (b) includes incrementally adjusting the bonding force applied to the bond head assembly of the wire bonding apparatus while detecting the z-height position of a portion of the bond head assembly.

52. The method of claim 51, wherein zero gram force is determined in connection with step (b).

53. A method as described in claim 51, in which, in relation to step (b), the desired force is determined such that incremental adjustments from step (b) do not result in a change in the z-height position of the bond head assembly.

54. A method as described in claim 51, in connection with step (b), wherein the desired force is determined such that incremental adjustments from step (b) result in a peak z-height position of the bond head assembly.

55. The method of claim 51, wherein step (b) occurs during a force control mode of operation of the wire bonding machine.

56. A method as described in claim 47, wherein step (b) includes a step of gradually reducing the force applied to the bond head assembly of the wire bonding apparatus while detecting the z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment.

57. A method as described in claim 56, in which, in relation to step (b), the force value is detected as the z-height position changes from the initial height due to the predetermined height adjustment.

58. The method of claim 56, wherein the step of gradually reducing the force is repeated for multiple cycles, each of the multiple cycles being used in conjunction with a step of monitoring the accuracy of the bonding force.

59. A method as described in claim 47, wherein step (b) includes a step of gradually increasing the force applied to the bond head assembly of the wire bonding apparatus while detecting the z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment.

60. A method as described in claim 59, in which, in relation to step (b), the force value is detected as the z-height position changes from the initial height due to the predetermined height adjustment.

61. A method as described in claim 59, wherein the step of gradually increasing the force is repeated for multiple cycles, each of the multiple cycles being used in conjunction with a step of monitoring the accuracy of the bonding force.

62. The method of claim 61, occurring during a position control mode of the wire bonding machine.

63. A method as described in claim 61, wherein an accurate zero gram force is determined in connection with step (b).

64. The method of claim 61, wherein the characteristics of the z-axis drive force are determined while substantially maintaining a predetermined z-axis position to monitor the accuracy of the bonding force.

65. The method of claim 64, wherein the characteristic is an electrical characteristic of the z-axis motor.

66. The method of claim 65, wherein the characteristic is the current of a z-axis motor that provides the driving force.

67. The method of claim 45, wherein step (b) occurs with a wire bonding tool positioned above a workpiece on the wire bonding apparatus but not in contact with the workpiece.

68. The method of claim 47, wherein step (b) occurs with a wire bonding tool in contact with a workpiece on the wire bonding apparatus.

69. A method of operating a wire bonding apparatus, comprising: (a) gradually increasing a bonding force applied to the bond head assembly while detecting a z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment; (b) detecting a bonding force value when the z-height position changes from the initial height due to the predetermined height adjustment, wherein after step (a), the z-height position continues to change until a peak height position is reached; A method comprising:

70. The method of claim 69, wherein after step (b), the method includes a step of gradually reducing the bonding force applied to the bond head assembly while detecting the z-height position of a portion of the bond head assembly until the z-height position returns to the initial height.

71. A method as described in claim 70, wherein the bonding force value is detected when the z-height position returns to the initial height.

72. A method as described in claim 69, wherein the bonding force is detected at the z height position where the peak height position is reached.

73. The method of claim 69, wherein steps (a) and (b) occur during a force control mode of operation of the wire bonding machine.

74. A method of operating a wire bonding apparatus, comprising: (a) gradually increasing a bonding force applied to the bond head assembly while detecting a z-height position of a portion of the bond head assembly until the z-height position changes from an initial height by a predetermined height adjustment; (b) detecting a bonding force value when the z-height position changes from the initial height due to the predetermined height adjustment, wherein steps (a) and (b) occur during a force control mode of operation of the wire bonding machine; A method comprising:

75. The method of claim 74, wherein after step (b), the method includes a step of gradually reducing the bonding force applied to the bond head assembly while detecting the z-height position of a portion of the bond head assembly until the z-height position returns to the initial height.

76. The method of claim 75, wherein the bonding force value is detected when the z-height position returns to the initial height.

77. The method of claim 74, wherein after step (a), the z height position continues to change until a peak height position is reached.

78. A method as described in claim 77, wherein the bonding force is detected at the z height position where the peak height position is reached.

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