BTO calibration system and method for fully automatic ball wire bonding machine

Abstract

This invention proposes a BTO (Body Tolerance) correction system and method for a fully automated ball wire bonding machine. The fully automated ball wire bonding machine includes a bonding area, a bonding head equipped with a ceramic nozzle and a vision recognition system, and an XY motion platform. The bonding head is located on the XY motion platform and is driven by the XY motion platform. The BTO correction system includes: a bonding facet located outside the bonding area, used for bonding balls with the ceramic nozzle to form a base point, which is then aligned and identified by the vision recognition system; a movement drive mechanism connected to the bonding facet, used to drive the bonding facet to move out of or into the ceramic nozzle's movement range; and a correction storage system used to store the current BTO value and obtain the movement distance required for the bonding head to move from the ceramic nozzle alignment point to the vision recognition system alignment point, thereby updating the current BTO value. This invention can automatically correct BTO, with high correction efficiency and reliability.

Description

Technical Field

[0001] This invention relates to the field of wire bonding machine technology, and in particular to a BTO correction system and method for a fully automatic ball wire bonding machine. Background Technology

[0002] A fully automatic wire bonding machine is a device that uses ultrasound, heat, and pressure to electrically connect metal wires to semiconductor chips and pins. It uses a transducer and a ceramic nozzle to apply ultrasonic vibrations to the bonding points, forming a fusion on the chip or pin in contact with the metal wire, thus achieving a strong electrical connection. The first solder joint is a ball bond, which uses high-voltage electronic arcing to heat the tip of the metal wire into a small ball, increasing the bonding strength. Typically, the first solder joint is bonded to the chip. The second solder joint is usually a wedge bond, where the friction between the ceramic nozzle and the frame, under the action of ultrasonic energy, achieves a reliable connection between the metal wire and the solder joint.

[0003] For each bonding point, the equipment needs to use a machine vision system to identify and calculate its position. Since the ultrasonic transducer and ceramic nozzle obstruct the bonding point, the vision recognition optical path needs to be moved to an unobstructed location to identify the bonding position. After the position is identified, the ceramic nozzle is then moved to that position to perform the bonding.

[0004] The distance between the ceramic tip and the optical path for identification is called the bond tip offset (BTO). Theoretically, once the optical path and the ceramic tip are fixed, the BTO is a constant. However, the reality is not so ideal. First, during device operation, the clamping stage needs to be heated to improve bonding efficiency. This heat is radiated through the air to the bonding head components. Due to differences in distance, structure, and materials, the relative positions of related components change, thus altering the BTO. Although the change caused by heat is a slow process, over time, the BTO deviation increases, ultimately leading to lower bonding accuracy. This necessitates frequent machine shutdowns and manual recalibration of the BTO, reducing equipment productivity. Furthermore, if post-soldering inspection is used, the metal wires on the solder balls can interfere with the visual image, making it difficult to obtain the precise position of the ball's center. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the above-mentioned problems, and proposes a BTO correction system and method for a fully automatic ball wire bonding machine. The device is simple and compact, can automatically and accurately correct the BTO value, does not require manual calibration without stopping the machine, has high correction efficiency and reliability, significantly improves the bonding accuracy of the bonding machine, and does not affect or interfere with the original normal bonding area and the movement of the ceramic nozzle.

[0006] The technical solution of this invention is as follows:

[0007] A BTO (Ball-to-Track) calibration system for a fully automatic ball-to-wire bonding machine, the fully automatic ball-to-wire bonding machine including a bonding area for carrying the ball strip, a bonding head equipped with a ceramic nozzle and a vision recognition system, and an XY motion platform. The bonding head is mounted on the XY motion platform, so that the bonding head is driven by the XY motion platform to have X-axis and Y-axis movement strokes. The BTO calibration system includes:

[0008] The bonding facet, located outside the bonding area, is used to bond the implanted ball with the ceramic nozzle, forming a base point and being aligned and identified by a visual recognition system.

[0009] The moving drive mechanism, connected to the bonding facet, is used to drive the bonding facet to move out of or into the ceramic nozzle's travel range.

[0010] The calibration storage system stores the current BTO value and obtains the movement distance required for the bonding head to move from the ceramic nozzle alignment base point to the vision recognition system alignment base point, thereby replacing and updating the current BTO value.

[0011] Furthermore, in the BTO calibration system of the fully automatic ball wire bonding machine of the present invention, the base point is set as the center of the ball implanted by the ceramic nozzle.

[0012] Furthermore, in the BTO correction system of the fully automatic ball wire bonding machine of the present invention, the moving drive mechanism is a flipping drive mechanism, the output end of which is connected to the bonding facet and used to drive the bonding facet to perform a flipping motion.

[0013] Furthermore, in the BTO correction system of the fully automatic ball wire bonding machine of the present invention, the moving drive mechanism includes a flip motor, a driving pulley, a driven pulley, and a flip arm. The output end of the flip motor is connected to the driving pulley, the driving pulley is connected to the driven pulley via a transmission belt, the driven pulley is coaxially fixed with the flip arm, and the bonding plane is set on the outer end of the flip arm.

[0014] Furthermore, in the BTO correction system of the fully automatic ball wire bonding machine of the present invention, the moving drive mechanism is a linear translation drive mechanism, the output end of which is connected to the bonding facet and used to drive the bonding facet to perform linear translational motion.

[0015] Furthermore, in the BTO correction system of the fully automatic ball wire bonding machine of the present invention, the output end of the moving drive mechanism is set without interference with the bonding area.

[0016] This invention also proposes a calibration method for a BTO calibration system of a fully automated ball wire bonding machine, comprising the following steps:

[0017] Step 1: Drive the moving drive mechanism to move the bonding facet into the motion stroke range of the ceramic nozzle;

[0018] Step 2: Use the XY platform to drive the bonding head to move until the ceramic nozzle is aligned with the bonding plane, and control the ceramic nozzle to bond the implanted ball on the bonding plane to form the base point;

[0019] Step 3: Use the XY platform to drive the bonding head from the ceramic nozzle aligned with the base point to the vision recognition system aligned with the recognition base point;

[0020] Step 4: The calibration storage system obtains the motion distance required for the above-mentioned movement process, and replaces and updates the current BTO value stored in the calibration storage system accordingly;

[0021] Step 5: Drive the moving drive mechanism to move the bonding facet out of the movement range of the ceramic nozzle;

[0022] Step Six: Repeat the above steps at intervals.

[0023] Furthermore, in the calibration method of the BTO calibration system of the fully automatic ball wire bonding machine of the present invention, in step four, the step of the calibration storage system acquiring the motion stroke required for the above-mentioned moving process is as follows:

[0024] The first position coordinates of the bonding head when the ceramic nozzle is aligned with the base point and the second position coordinates when the visual recognition system is aligned with the base point are obtained sequentially; the difference between the first position coordinates and the second position coordinates is calculated.

[0025] The beneficial effects of this invention are:

[0026] 1. This invention designs a movable bonding plane outside the bonding area, which is used to move within the travel range of the ceramic tip at intervals to implant a metal ball. The existing vision recognition system is used to align and identify the movement to obtain the travel amount and update the BTO value. The device is small, simple, and inexpensive. It can realize automated control and correction without stopping the machine for manual calibration. The correction is reliable, accurate and efficient, effectively improving the bonding accuracy of the fully automatic ball wire bonding machine.

[0027] 2. The travel range of the bonding facet of the present invention does not interfere with or affect the original bonding area, and the device is not placed on the bonding chip, lead frame or other workpieces. It can be moved out of the travel range of the ceramic nozzle after each calibration, without interfering with the normal bonding movement of the bonding head. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the fully automatic ball wire bonding machine of the present invention.

[0029] Figure 2 This is a schematic diagram of the BTO correction system of the present invention in the correction state.

[0030] Figure 3This is a schematic diagram of the BTO correction system of the present invention when it is not in a correction state. Detailed Implementation

[0031] The present invention will now be further described with reference to the accompanying drawings:

[0032] Reference Figure 1 This embodiment discloses a BTO correction system for a fully automatic ball wire bonding machine. The fully automatic ball wire bonding machine includes a bonding area 1 for carrying the material strip, a bonding head 2 equipped with a ceramic nozzle 3 and a vision recognition system 4, and an XY motion platform 5. The bonding head 2 is mounted on the XY motion platform 5, so that the bonding head 2 is driven by the XY motion platform 5 and has X-axis and Y-axis movement strokes.

[0033] The BTO correction system includes:

[0034] A bonding facet 6, located outside the bonding region 1, is used to bond the ball to the ceramic nozzle 3, forming a base point and being aligned and identified by the visual recognition system 4; wherein, the base point is set as the center of the ball bonded by the ceramic nozzle 3.

[0035] The moving drive mechanism 7 is connected to the bonding facet 6 and is used to drive the bonding facet 6 to move out of or into the motion range of the ceramic nozzle 3.

[0036] The calibration storage system is used to store the current BTO value and obtain the movement distance required for the bonding head 2 to move from the ceramic nozzle 3 to the base point and the vision recognition system 4 to the recognition base point, thereby replacing and updating the current BTO value.

[0037] The moving drive mechanism 7 is either a flipping drive mechanism or a linear translation drive mechanism, and its output end is connected to the bonding facet 6 to drive the bonding facet 6 to perform flipping or linear translation movements. The output end of the moving drive mechanism 7 is arranged without interference with the bonding region 1. In this embodiment, the bonding region 1, the BTO correction system, and the bonding head 2 are arranged sequentially in the Y direction. The bonding facet of the BTO correction system moves in or out along the X direction, and its movement does not interfere with the bonding region 1.

[0038] Reference Figure 2 and Figure 3Specifically, when using a flip-drive method, the moving drive mechanism 7 includes a flip motor 701, a driving pulley 702, a driven pulley 703, and a flip arm 704. The output end of the flip motor 701 is fitted with the driving pulley 702, which is connected to the driven pulley 703 via a transmission belt. The driven pulley 703 is coaxially fixed with the flip arm 704, and the bonding facet 6 is located on the outer end of the flip arm 704. During calibration, the flip motor 701 drives the driving pulley 702 to rotate, which is transmitted to the driven pulley 703 via the transmission belt. The driven pulley 703 drives the flip arm 704 to flip, allowing the bonding facet 6 to flip and enter below the ceramic nozzle 3. After calibration, the flip motor 701 is controlled to flip the bonding facet 6 away from the travel range of the ceramic nozzle 3 without affecting subsequent normal bonding operations.

[0039] Based on the above structure, this embodiment also proposes a calibration method for the BTO calibration system of a fully automated ball wire bonding machine, including the following steps:

[0040] Step 1: Drive the moving drive mechanism 7 to move the bonding facet 6 into the motion stroke range of the ceramic nozzle 3;

[0041] Step 2: Use the XY platform 5 to drive the bonding head 2 to move the ceramic nozzle 3 to the bonding plane 6, and control the ceramic nozzle 3 to bond the ball on the bonding plane 6, with the center of the ball bonded by the ceramic nozzle 3 forming the base point;

[0042] Step 3: Using the XY platform 5 to drive the bonding head 2 from the ceramic nozzle 3 aligned with the base point to the vision recognition system 4 aligned with the recognition base point;

[0043] Step 4: The calibration storage system obtains the motion distance required for the above-mentioned movement process, and replaces and updates the current BTO value stored in the calibration storage system accordingly;

[0044] Step 5: Drive the moving drive mechanism 7 to move the bonding facet 6 out of the motion range of the ceramic nozzle 3;

[0045] Step Six: Repeat the above steps at intervals.

[0046] In step four, the step of correcting the storage system to obtain the motion distance required for the above-mentioned movement process is as follows:

[0047] The first position coordinates of the bonding head 2 when the ceramic nozzle 3 is aligned with the base point and the second position coordinates of the vision recognition system 4 when the base point is aligned are obtained sequentially; the difference between the first position coordinates and the second position coordinates is calculated.

[0048] This invention enables automatic intelligent correction at intervals, achieving periodic updates of BTO values, effectively avoiding error fluctuations caused by temperature effects on BTO, and boasts high correction efficiency and reliability, requiring no downtime or manual correction and debugging.

[0049] The specific embodiments described herein are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A BTO correction system for a fully automatic ball wire bonding machine, the fully automatic ball wire bonding machine comprising a bonding area for carrying the wire strip, a bonding head equipped with a ceramic nozzle and a vision recognition system, and an XY motion platform, wherein the bonding head is mounted on the XY motion platform, and the bonding head is driven by the XY motion platform to have X-axis and Y-axis movement strokes, characterized in that: The BTO correction system includes: The bonding facet, located outside the bonding area, is used for the cyclic bonding of the ceramic nozzle onto the implanted ball, forming a base point that is aligned and identified by a visual recognition system. The moving drive mechanism, connected to the bonding facet, is used to drive the bonding facet to move out of or into the ceramic nozzle's travel range. The calibration storage system stores the current BTO value and obtains the movement distance required for the bonding head to move from the ceramic nozzle alignment base point to the vision recognition system alignment base point, thereby replacing and updating the current BTO value.

2. The BTO correction system for the fully automatic ball wire bonding machine according to claim 1, characterized in that: The base point is set as the center of the ball implanted by the ceramic nozzle.

3. The BTO correction system for the fully automatic ball wire bonding machine according to claim 1, characterized in that: The moving drive mechanism is a flipping drive mechanism, and its output end is connected to the bonding plane to drive the bonding plane to flip.

4. The BTO correction system of the fully automatic ball wire bonding machine according to claim 3, characterized in that: The moving drive mechanism includes a tilting motor, a driving pulley, a driven pulley, and a tilting arm. The output end of the tilting motor is fitted with the driving pulley, which is connected to the driven pulley via a transmission belt. The driven pulley is coaxially fixed with the tilting arm, and a keying plane is set on the outer end of the tilting arm.

5. The BTO correction system for the fully automatic ball wire bonding machine according to claim 1, characterized in that: The moving drive mechanism is a linear translation drive mechanism, and its output end is connected to the bonding plane to drive the bonding plane to perform linear translational motion.

6. The BTO correction system for a fully automatic ball wire bonding machine according to claim 3 or 5, characterized in that: The output end of the moving drive mechanism is set in a non-interference manner with the bonding area.

7. A calibration method for a BTO calibration system of a fully automatic ball wire bonding machine according to any one of claims 1-5, characterized in that: Includes the following steps: Step 1: Drive the moving drive mechanism to move the bonding facet into the motion stroke range of the ceramic nozzle; Step 2: Use the XY platform to drive the bonding head to move until the ceramic nozzle is aligned with the bonding plane, and control the ceramic nozzle to bond the implanted ball on the bonding plane to form the base point; Step 3: Use the XY platform to drive the bonding head from the ceramic nozzle aligned with the base point to the vision recognition system aligned with the recognition base point; Step 4: The calibration storage system obtains the motion distance required for the above-mentioned movement process, and replaces and updates the current BTO value stored in the calibration storage system accordingly; Step 5: Drive the moving drive mechanism to move the bonding facet out of the movement range of the ceramic nozzle; Step Six: Repeat the above steps at intervals.

8. The calibration method of the BTO calibration system of the fully automatic ball wire bonding machine according to claim 7, characterized in that: In step four, the step of correcting the storage system to obtain the motion distance required for the above-mentioned movement process is as follows: The first position coordinates of the bonding head when the ceramic nozzle is aligned with the base point and the second position coordinates when the visual recognition system is aligned with the base point are obtained sequentially; the difference between the first position coordinates and the second position coordinates is calculated.

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