Optimization method for bonding tangent line depth and bonding structure
In the post-cutting method of aluminum wire bonding, by acquiring and verifying the real-time induced voltage and adjusting the tangent depth, the problem of tangent depth deviation caused by tangent instability is solved, and the stable cutting and welding continuity of the bonded wire is achieved.
Patent Information
- Application Number
- CN202311832003.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-28
- Publication Date
- 2025-07-01
AI Technical Summary
In the post-cutting method of aluminum wire bonding, tangent instability leads to a deviation in the depth of the tangent, which may lead to inconsistent length of the bonded wire or failure of welding, and even lead to collision between the cutting knife and the substrate to damage the substrate.
By obtaining the wire diameter of the bonding line, calculating the depth of the calibration line, and pre-cutting and grouping test cutting by controlling the cutter, obtaining real-time induced voltage, verifying its normal distribution, adjusting the tangent depth to adapt to the test of the bonding line, and ensuring that the tangent depth reaches the calibration value.
The stability of the tangent depth is achieved, the continuity of welding is ensured, and the problems of inconsistent or inability to cut the tail length of the bonded line caused by the small tangent depth are avoided, as well as the problem of the cutting knife and the substrate collision and damage the substrate caused by the large tangent depth are caused.
Smart Images
Figure CN120237006A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of semiconductor bonding, and particularly relates to an optimization method for bonding tangent depth and a bonding structure. Background Art
[0002] With the development of semiconductor processing technology, ultrasonic welding technology has been more and more widely used. Ultrasonic welding uses high-frequency vibration waves to transfer energy to the surfaces of two objects to be welded. Under pressure, the surfaces of the two objects rub against each other to form a fusion between molecular layers. Due to the characteristics of high efficiency and high connection strength of the ultrasonic welding process, it is widely used in the welding process of semiconductor components.
[0003] As a mainstream method in the field of microelectronic packaging, thick aluminum wire bonding has the advantages of large current-carrying capacity and low cost. According to the installation position of the capillary, the wire cutting method of thick aluminum wire can be divided into front cutting and back cutting. The capillary of the front cutting method is installed before the cutter and the bonding wire nozzle, while the capillary of the back cutting method is installed in the middle position. The traditional tangent method usually cuts a part of the wire diameter of the bonding wire. The remaining bonding wire will be broken by the movement of the bonding head under the fixation of the capillary and the bonding wire nozzle.
[0004] In practical applications, the inventor found that the prior art has at least the following problems:
[0005] In the back cutting method of aluminum wire bonding, there is a phenomenon of unstable tangent. Due to the change in height after welding, there is an error in the control of the tangent action. In actual operation, the actual tangent depth usually deviates from the set depth, and the tangent depth often shows a normal distribution within the preset value range. If the tangent depth is less than the set depth, it may lead to inconsistent tail lengths of the bonding wire, or even the aluminum wire cannot be cut off, resulting in welding failure. If the tangent depth is greater than the set depth, it may cause the aluminum wire to be completely cut off before pulling the wire, easily leading to a collision between the cutter and the substrate and damaging the substrate.
[0006] In view of this, it is necessary to improve the defects existing in the prior art to overcome the deficiencies in actual applications. Summary of the Invention
[0007] Based on the above-mentioned drawbacks and deficiencies in the prior art, one of the purposes of the present invention is to at least solve one or more of the above problems existing in the prior art. In other words, one of the purposes of the present invention is to provide an optimization method for bonding tangent depth and a bonding structure that meet one or more of the foregoing requirements.
[0008] To achieve the above invention purpose, the present invention adopts the following technical solutions:
[0009] The present invention provides an optimization method for bonding tangent depth, including the following steps:
[0010] S1. Obtain the wire diameter of the bonding wire and calculate the calibrated tangent depth according to the wire diameter;
[0011] S2. Pre-cut the bonding wire by controlling the cutter and obtain the calibrated induction voltage;
[0012] S3. Group-test cut the bonding wires at different welding positions in sequence by controlling the cutter to obtain the real-time induction voltage during wire pulling, and verify whether the real-time induction voltage of each group conforms to the normal distribution;
[0013] S4. Continuously adjust the real-time tangent depth according to the real-time induction voltage to adapt to the test of the bonding wire, judge whether the real-time tangent depth after each test reaches the calibrated tangent depth, and perform standardized cutting on the bonding wires at different welding positions by controlling the cutter.
[0014] As a preferred solution, the ratio of the calibrated tangent depth to the wire diameter of the bonding wire is 70% - 80%.
[0015] As a preferred solution, the step S2 specifically includes:
[0016] By controlling the cutter to move downward from the initial position to the tangent position, the pre-cut depth of the bonding wire is the calibrated tangent depth H0, and the calibrated tangent depth H0 is input into the system; wherein, the calibrated induction voltage corresponding to the calibrated tangent depth H0 is U0.
[0017] As a preferred solution, the step S3 specifically includes:
[0018] S31. Group-test cut the bonding wires at different welding positions in sequence by controlling the cutter and obtain the real-time induction voltage Uij; wherein, the number of times of test-cutting the bonding wire in each group is not less than four, i represents the test group number, j represents the number of wire pulling times within the corresponding group, and both i and j are positive integers;
[0019] S32. Verify whether the real-time induction voltage Uij conforms to the normal distribution, calculate the average value of the tangent depth of each group, and use the average value of the tangent depth as the benchmark for the next group of test-cutting the bonding wire.
[0020] As a preferred solution, the step S4 includes:
[0021] S41. Compare the mean voltage of the real-time induction voltage Uij of each group with the calibrated induction voltage U0 to obtain the tangent depth during standardized cutting;
[0022] S42. Judge whether the tangent depth reaches the calibrated tangent depth. If the mean voltage is less than the calibrated induction voltage U0, then reduce the unit tangent depth; if the mean voltage If it is greater than the calibrated voltage U0, then increase the unit tangent depth.
[0023] As a preferred solution, step S42 further includes:
[0024] S421. When the sample size has not reached the upper limit value, by judging the mean voltage and the calibrated induced voltage U0, if the mean voltage is less than the calibrated induced voltage U0 when increasing the unit tangent depth by one unit, and at the same time, if the mean voltage is greater than the calibrated induced voltage U0 when decreasing the unit tangent depth by one unit, then increase the sample size of each group of tests and repeat the above judgment steps;
[0025] S422. When the sample size reaches the upper limit value, terminate the adjustment of the tangent depth and use the current tangent depth as the tangent depth during standardized cutting.
[0026] As a preferred solution, the unit tangent depth is 0.5 - 10 μm.
[0027] As a preferred solution, the speed ratio of the pre - cutting to the standardized cutting is 10% - 30%.
[0028] The present invention also provides a bonding structure for bonding tangent depth, which is applied to the method described in any of the above solutions. The bonding structure includes a power seat, a coil, a bonding tool, a cutting tool, and a wire clamp. The power seat drives the cutting tool and the bonding tool to move. The bonding tool is used to weld the bonding wire to the substrate, the cutting tool is used to cut the welded bonding wire, and the wire clamp is used to break the cut bonding wire.
[0029] As a preferred solution, a magnet is installed on the power seat, the magnet is arranged inside the coil, and the power seat moves relative to the coil to generate a real - time induced voltage inside the coil.
[0030] Compared with the prior art, the beneficial effects of the present invention are:
[0031] The present invention provides an optimization method for bonding tangent depth. By continuously optimizing the tangent depth of the bonding wire, the tangent depth is maintained within a stable range, ensuring the continuity of welding. It can avoid the inconsistent tail length of the bonding wire due to too small tangent depth, or even the failure of welding because the aluminum wire cannot be cut off, and also avoid the complete cutting of the aluminum wire before wire pulling due to too large tangent depth, resulting in the collision between the cutting tool and the substrate and damaging the substrate. Description of the Drawings
[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings of other embodiments can be obtained based on these drawings.
[0033] Figure 1 is a flowchart of an optimization method for bonding tangent depth according to an embodiment of the present invention;
[0034] Figure 2 is a normal distribution diagram of the real-time induced voltage obtained by verification according to an embodiment of the present invention;
[0035] Figure 3 is a comparison diagram of the relationship between the induced voltage and the tangent depth according to an embodiment of the present invention;
[0036] Figure 4 is a partially enlarged schematic diagram of the tangent state according to an embodiment of the present invention;
[0037] Figure 5 is a partially enlarged schematic diagram of the wire clamp wire feeding state according to an embodiment of the present invention. Specific Embodiments
[0038] To more clearly illustrate the embodiments of the present invention, the following will describe the specific embodiments of the present invention with reference to the drawings. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings and other embodiments can be obtained based on these drawings.
[0039] In the description of the embodiments of the present invention, the orientation or positional relationships such as "upper", "lower", "front", "rear", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention.
[0040] According to some embodiments of the present application, please refer to Figure 1 as shown, there is provided an optimization method for bonding tangent depth, including the following steps:
[0041] S1. Obtain the wire diameter of the bonding wire and calculate the calibrated tangent depth according to the wire diameter;
[0042] S2. Pre-cut the bonding wire by controlling the cutter and obtain the calibrated induced voltage;
[0043] S3. Sequentially perform grouped test cuts on the bonding wires at different welding positions by controlling the cutting tool to obtain the real-time induced voltage during wire pulling, and verify whether the real-time induced voltage of each group conforms to the normal distribution;
[0044] S4. Continuously adjust the real-time cutting depth according to the real-time induced voltage to adapt to the test of the bonding wire, determine whether the real-time cutting depth after each test reaches the calibrated cutting depth, and perform standardized cutting on the bonding wires at different welding positions by controlling the cutting tool.
[0045] After the bonding wire is welded to the substrate by the splitting tool, the cutting tool is required to cut the bonding wire. After cutting to a certain depth, the remaining uncut part is broken by the cutting tool, and the welding, cutting, and wire pulling of different welding positions are completed in sequence.
[0046] When the ratio of the cutting depth to the wire diameter of the bonding wire is too small, it is easy to fail to break the remaining bonding wire by relying on the movement of the cutting tool. When the ratio of the cutting depth to the wire diameter of the bonding wire is too large, the bonding wire is easily cut off by the cutting tool at one time, and the cutting tool overshoots during cutting and damages the substrate.
[0047] Further, S1. Obtain the wire diameter of the bonding wire and calculate the calibrated cutting depth according to the wire diameter, specifically including:
[0048] Since the wire diameter of the bonding wire required for each batch of welding remains consistent, the wire diameter of the bonding wire is obtained before welding, the calibrated cutting depth is calculated according to the wire diameter, and the calibrated cutting depth is input into the system.
[0049] In order to break the bonding wire by controlling the movement of the cutting tool and avoid the problem that the cutting tool cuts off all the bonding wires at one time or fails to break when the cutting depth does not reach the standard, the ratio of the calibrated cutting depth to the wire diameter of the bonding wire is set to 70% - 80% in the system to meet the requirement of the cutting tool for wire pulling. In practical applications, the ratio of the cutting depth to the wire diameter of the bonding wire can be set to 70%, 75%, 80%, and the preferred setting ratio is 80%.
[0050] Further, S2. Perform a pre-cut on the bonding wire by controlling the cutting tool and obtain the calibrated induced voltage, specifically including:
[0051] Control the cutting tool to move downward from the initial position to the cutting position to perform a pre-cut on the bonding wire with a depth of the calibrated cutting depth H0, and input the calibrated cutting depth H0 into the system; where the calibrated induced voltage corresponding to the calibrated cutting depth H0 is U0.
[0052] By obtaining the calibrated induction voltage U0 corresponding to the calibrated tangent depth H0 during pre-cutting, using the calibrated induction voltage U0 as a reference parameter for subsequent tangent tests, and feeding back the real-time tangent depth through the real-time induction voltage during each test, and then adjusting the tangent depth during the next cut to better control the consistency of the tangent depth.
[0053] Further, in S3, the cutter is controlled to perform grouped test cuts on the bonding wires at different welding positions in sequence to obtain the real-time induction voltage during wire pulling, and verify whether the real-time induction voltage of each group conforms to the normal distribution, specifically including:
[0054] In S31, the cutter is controlled to perform grouped test cuts on the bonding wires at different welding positions in sequence, and the real-time induction voltage Uij is obtained; where the number of times of test cutting the bonding wires in each group is not less than four, i represents the number of test groups, j represents the number of times of wire pulling within the corresponding group, and both i and j are positive integers.
[0055] When pulling the wire by controlling the movement of the cutter, there is a coil on the power seat connecting the cutter, and a magnet is arranged inside the coil. The power seat moves relative to the coil to generate a real-time induction voltage inside the coil. By dividing the welding sample size into i groups for testing, the number of times of wire pulling within each group is at least four, and the real-time induction voltage of each wire pulling is obtained.
[0056] In S32, verify whether the real-time induction voltage Uij conforms to the normal distribution, calculate the average value of the tangent depth of each group, and use the average value of the tangent depth as the reference for the next group of test cuts on the bonding wires.
[0057] By judging whether the real-time induction voltage generated during each group of tests conforms to the normal distribution. If so, calculate the average value of the tangent depth of each group, and use the average value of the tangent depth as the reference for the next group of test cuts on the bonding wires, and repeat this to complete the tests on all sample sizes; if not, check the stability of the system and perform debugging to make the real-time induction voltage of the test meet the normal distribution.
[0058] As Figure 2 shown, the real-time induction voltage obtained by testing multiple groups of data satisfies the normal distribution characteristics.
[0059] Further, in S4, the real-time tangent depth is continuously adjusted according to the real-time induction voltage to adapt to the test of the bonding wire, and it is judged whether the real-time tangent depth after each test reaches the calibrated tangent depth, and the cutter is controlled to perform standardized cuts on the bonding wires at different welding positions, specifically including:
[0060] In S41, according to the mean voltage of the real-time induction voltage Uij of each group, compare it with the calibrated induction voltage U0 to obtain the tangent depth during standardized cutting.
[0061] S42. Determine whether the tangent depth reaches the calibrated tangent depth. If the average voltage is less than the calibrated induction voltage U0, reduce the unit tangent depth; if the average voltage is greater than the calibrated voltage U0, increase the unit tangent depth.
[0062] Furthermore, step S42 further includes:
[0063] S421. When the sample size does not reach the upper limit value, by judging the average voltage and the calibrated induction voltage U0, if increasing a unit tangent depth, the average voltage is less than the calibrated induction voltage U0, and at the same time, if reducing a unit tangent depth, the average voltage is greater than the calibrated induction voltage U0, then increase the sample size of each group of tests and repeat the above judgment steps;
[0064] S422. When the sample size reaches the upper limit value, terminate the adjustment of the tangent depth and use the current tangent depth as the tangent depth during standardized cutting.
[0065] During the process of breaking after tangential cutting, the splitting knife and the bonding wire will be subjected to an upward acting force, causing the spring piece in the power seat to have an upward deformation, the linkage magnet moves relative to the coil, generating a real-time induction voltage. Since the voltage generated during the stable tangential cutting process is constant, if the tangent depth changes, the voltage will fluctuate relatively.
[0066] As Figure 3 shown, by continuously adjusting the tangent depth, the relationship comparison diagram between the corresponding induction voltage and the tangent depth. In order to ensure the adjusted tangent depth during each test, the unit tangent depth is specified as 0.5 - 10 μm, preferably the unit tangent depth is 1 μm, and it can be specifically set according to actual requirements.
[0067] In this embodiment, the speed ratio of pre-cutting to standardized cutting is 10% - 30%.
[0068] In order to accurately obtain the calibrated induction voltage during cutting, it is necessary to control the speed during the pre-cutting of the bonding wire. Generally speaking, the speed ratio of pre-cutting to standardized cutting is 10% - 30%, preferably the ratio is set to 20%, and it can be specifically set according to actual requirements.
[0069] This embodiment also provides a bonding structure for bonding tangent depth, which is applied to the method as described above. The bonding structure includes a power seat, a wire clamp 1, a splitting knife 2, a cutting knife 3, and a coil. The power seat drives the cutting knife 3 and the splitting knife 2 to move. The splitting knife 2 is used to weld the bonding wire to the substrate, the cutting knife 3 is used to cut the welded bonding wire, and the wire clamp 1 is used to break the cut bonding wire.
[0070] Further, a magnet is installed on the power seat. The magnet is disposed within the coil, and the power seat moves relative to the coil to generate a real-time induced voltage within the coil.
[0071] According to some embodiments of the present application, Figure 4 A schematic diagram showing the state when the cutting tool cuts the wire is shown. Figure 5 A schematic diagram showing the state of the wire clamp feeding the wire is shown. The bonding wire 4 is conveyed to the welding position through the wire clamp 1, then the bonding wire 4 is welded to the substrate through the splitting tool 2, then the bonding wire 4 is cut by the cutting tool 3, and finally the bonding wire 4 is broken by the lateral movement of the wire clamp 1, and the bonding wire 4 is conveyed to the next welding position through the power seat. The above process is repeated to continuously weld the bonding wire to the substrate, ensuring the welding continuity and welding stability.
[0072] For those skilled in the art, the above disclosure is merely an example and does not constitute a limitation to the present application. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and corrections to the present application. Such modifications, improvements, and corrections are proposed in the present application, so such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of the present application.
[0073] Although the present application has been described with reference to the current specific embodiments, those of ordinary skill in the art in the technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and variations of the above embodiments are within the scope of the spirit of the present application, they will fall within the scope of the claims of the present application.
Claims
1. An optimization method for bonding tangent depth, characterized in that, It includes the following steps: S1. Obtain the wire diameter of the bonding wire and calculate the calibrated tangent depth according to the wire diameter; S2. Control the cutter to pre-cut the bonding wire and obtain the calibrated induction voltage; S3. Control the cutter to perform grouped test cuts on the bonding wires at different welding positions in sequence to obtain the real-time induction voltage during wire pulling, and verify whether the real-time induction voltage of each group conforms to the normal distribution; S4. Continuously adjust the real-time tangent depth according to the real-time induction voltage to adapt to the test of the bonding wire, judge whether the real-time tangent depth after each test reaches the calibrated tangent depth, and control the cutter to perform standardized cuts on the bonding wires at different welding positions.
2. The optimization method for the bonding and cutting depth according to claim 1, characterized in that, The ratio of the calibrated tangent depth to the wire diameter of the bonding wire is 70% - 80%.
3. The optimization method for bonding and cutting depth according to claim 1, characterized in that The specific content of step S2 includes: Control the cutter to move downward from the initial position to the tangent position to pre-cut the bonding wire to a depth of the calibrated tangent depth H0, and input the calibrated tangent depth H0 into the system; among them, the calibrated induction voltage corresponding to the calibrated tangent depth H0 is U0.
4. An optimization method for the bonding and cutting depth according to claim 1, characterized in that The specific content of step S3 includes: S31. Control the cutter to perform grouped test cuts on the bonding wires at different welding positions in sequence and obtain the real-time induction voltage Uij; among them, the number of times of test cutting the bonding wire in each group is not less than four times, i represents the number of test groups, j represents the number of wire pulling times within the corresponding group, and both i and j are positive integers; S32. Verify whether the real-time induction voltage Uij conforms to the normal distribution, calculate the average value of the tangent depth of each group, and use the average value of the tangent depth as the benchmark for the next group of test cuts on the bonding wire.
5. An optimization method for the bonding and cutting depth according to claim 1, characterized in that The content of step S4 includes: S41. According to the mean voltage of each group of real-time induced voltages Uij compare with the calibrated induced voltage U0 to obtain the tangent depth during standardized cutting; S42. Determine whether the tangent depth reaches the calibrated tangent depth. If the average voltage is less than the calibrated induction voltage U0, reduce the unit tangent depth; if the average voltage is greater than the calibrated voltage U0, increase the unit tangent depth.
6. The optimization method for the bonding and cutting depth according to claim 5, wherein The content of step S42 also includes: S421. When the sample size has not reached the upper limit value, by judging the mean voltage and the calibrated induction voltage U0, if increasing a unit tangent depth, the mean voltage is less than the calibrated induction voltage U0, and at the same time if decreasing a unit tangent depth, the mean voltage is greater than the calibrated induction voltage U0, then increase the sample size of each group of tests and repeat the above judgment steps; S422. When the sample size reaches the upper limit value, terminate the adjustment of the tangent depth and use the current tangent depth as the tangent depth during standardized cutting.
7. An optimization method for bonding and cutting depth according to claim 5, characterized in that The unit tangent depth is 0.5 - 10 μm.
8. The optimization method for the bonding and cutting depth according to claim 1, characterized in that, The ratio of the speed of pre-cutting to the speed of standardized cutting is 10% - 30%.
9. A bonding structure for bonding tangent depth, characterized in that, Applied to the method described in any one of claims 1 - 8, the bonding structure includes a power seat, a coil, a bonding tool, a cutter, and a wire clamp. The power seat drives the cutter and the bonding tool to move. The bonding tool is used to weld the bonding wire to the substrate. The cutter is used to cut the welded bonding wire. The wire clamp is used to break the cut bonding wire.
10. A bonding structure for bonding and cutting depth according to claim 9, characterized in that, A magnet is installed on the power seat. The magnet is arranged inside the coil. The power seat moves relative to the coil to generate a real-time induction voltage inside the coil.