Vertical line arc forming method and forming device of full-automatic wire welding machine

Abstract

The invention relates to a semiconductor packaging method, in particular to a vertical line arc forming method and a vertical line arc forming device of a full-automatic wire welding machine. The method comprises the following steps: paying off a wire tail to form a wire tail, forming an ablation gap on the wire by using a fixed laser, and taking up to form a ball burning wire tail; burning the balls to form metal solder balls; welding and reballing to enable the metal solder balls to be welded and fixed on the welding spots of the substrate; pulling the vertical arc so as to pull out a vertical arc with a specified height on the substrate; and reserving a new line tail. The wire notch obtained through the method is not generated by pressing the wire through the cleaver ceramic nozzle and the welding position, but the notch is directly ablated in the wire through the high-energy laser beam generated by the laser, and therefore the quality and the use condition of the ceramic nozzle cannot affect forming of the wire notch. The overall vertical degree of the wire rod is high, the bending and inclining phenomenon of the wire arc neck is avoided, and the vertical wire arc quality is good; and secondary welding is not needed, and the arc discharge welding efficiency is high.

Description

Technical Field

[0001] This invention relates to a semiconductor packaging method, and more particularly to a method and apparatus for forming vertical arc lines using a fully automated wire bonding machine. Background Technology

[0002] The gold ball wire bonding machine first completes the pre-processing, loading the wire and calibrating the ceramic nozzle. It then positions the chip substrate using a vision system and sets parameters such as the heating stage temperature and ultrasonic power. The wire end extends from the ceramic nozzle, and the electrodes of the discharge-sinking device generate an electric arc, melting the wire into a metal solder ball. The ceramic nozzle moves downwards, causing the metal solder ball to adhere to the substrate and applying pressure. Under the combined action of heating, ultrasonic waves, and pressure, atomic diffusion occurs between the wire and the solder pad metal, forming a weld point. After the pressure is applied and the weld point is solidified, the wire arc welding is complete. This welding method is commonly used for ordinary wire arc welding.

[0003] However, as packaging technology develops towards stacked packaging, new demands are placed on the shape of the arc. Ordinary arcs can only meet the welding packaging requirements of two-dimensional planes. Therefore, the demand for vertical arcs with a certain height in three-dimensional space for stacked packaging has emerged.

[0004] Currently, one method for welding vertical arc wires is to use a method similar to conventional welding. First, the first solder joint is directly completed on the wafer solder joint, but the second solder joint is not welded. Instead, the ceramic nozzle is used to press the wire into a notch by pressing it against the pad. Then, the vertical arc wire is pulled out by moving upwards and the wire is broken at the notch to form a new wire tail.

[0005] Another method for welding vertical arc wires is to first set an additional pressing position outside the wafer pad, with its height between the wire tail and the set bending height; leave enough wire tail first, then move to the additional pressing position, use the height difference between the wire tail and the pressing position to bend the long wire tail, and use the ceramic nozzle to bend and press at the additional pressing position to press out a notch in the wire at the bending height, then take the wire back, heat the ball to complete one weld, move upward to pull out the vertical arc wire and break the wire at the notch to form a new wire tail.

[0006] Current methods for forming vertical arcs have the following shortcomings: The first welding method uses a similar conventional wire bonding method, which involves arc pulling after the first weld, causing the neck of the arc to bend. When welding vertical arcs using this method, it is easy for the arc to bend and tilt. In addition, because this method involves a second weld, it requires a certain amount of space to perform, which may be limited by the wafer size and may not have a notch pressing position, making it impossible to weld vertical arcs.

[0007] Another welding method avoids the wafer size space constraints of wire bonding gaps and does not involve a second welding operation, which can improve the problem of wire neck bending. However, the wire gap is generated by the bending and pressing of the ceramic nozzle, which requires high-quality ceramic nozzles. If the bending and pressing of the ceramic nozzle on the wire is insufficient, the new wire tail will retract into the ceramic nozzle when the wire tail breaks, shortening the wire tail and making the wire tail length unstable. If the bending and pressing of the ceramic nozzle on the wire is too large, the wire is flattened to a large extent, making the wire size at the gap position larger than the specified deformation degree, resulting in unsmooth wire take-up. If the bending and pressing of the ceramic nozzle on the wire is too large, the wire is flattened to an excessive degree, and the wire size at the gap position may even be larger than the diameter of the ceramic nozzle, clogging the ceramic nozzle and breaking the wire during the take-up process.

[0008] Both of the above methods generate wire gaps by pressing the wire together with the ceramic nozzle and the welding position. Therefore, the quality and usage of the ceramic nozzle will affect the shape of the wire gap, ultimately leading to unstable wire arc height or even a gap that is too shallow. During the wire breakage stage, a solder joint will be peeled off from the solder pad, resulting in failure of vertical wire arc welding. Summary of the Invention

[0009] To address the above problems, this invention provides a method for forming vertical arcs in a fully automatic wire bonding machine, the specific technical solution of which is as follows: A method for forming a vertical wire arc in a fully automatic wire bonding machine includes the following steps: Wire tail extension: Extending a section of wire from the cleaver nozzle to form a wire tail; Fixed laser notching: Activating the laser to irradiate the wire at the focal point, causing the irradiated portion of the wire to melt, ablate, and evaporate, ultimately forming an ablation notch on the wire, reducing the mechanical strength at that location; Wire retraction: Retracting a portion of the wire tail, including the laser-ablated weakened portion, into the cleaver nozzle to form a sintered wire tail; Sintering: Activating the discharge sintering device to generate... A high-temperature electric arc rapidly melts the tail of the solder ball into a metal solder ball; solder ball placement: the wedge-shaped ceramic nozzle carries the metal solder ball and presses it against the substrate, applying pressure. Under the combined action of heating, ultrasound, and pressure, the metal solder ball is welded and fixed to the substrate solder joint; drawing a vertical arc: the wedge-shaped ceramic nozzle moves vertically upward to a certain height, drawing a vertical arc of a specified height on the substrate; leaving a new tail: the clamping device is activated, breaking the arc and leaving a metal solder ball and a vertical arc on the substrate, leaving a new tail at the wedge-shaped ceramic nozzle to prepare for the next solder joint.

[0010] Preferably, when releasing the wire tail, the upper clamping device opens, the lower clamping device clamps the wire and drives the wire through the transducer and the tip of the cleaver nozzle, and the wire extends a certain length out of the cleaver nozzle to form the wire tail.

[0011] Preferably, when fixing the laser notch, the lower clamping device clamps and cooperates with the cleaving ceramic nozzle, driving the wire tail to the focal position of the laser, and then the laser is started to form an ablation notch on the wire through laser ablation.

[0012] Preferably, when retracting the wire, the laser stops working, the upper clamping device clamps the wire, the lower clamping device releases the wire, and the lower clamping device, transducer, and cleaver ceramic nozzle all move downward to the set position. Then the upper clamping device releases the wire, and the lower clamping device clamps the wire and lifts it up, so that the length of the wire tail formed at the tip of the ceramic nozzle is shortened and becomes a burnt ball wire tail, while making the end of the burnt ball wire tail consistent with the height of the discharge burnt ball device.

[0013] Preferably, during the soldering process, the discharge soldering device is activated, causing the air between the discharge soldering device and the wire to be broken down by high voltage, generating a high-temperature electric arc, so that the metal at the end of the soldering wire melts rapidly and cools to form a metal solder ball.

[0014] Preferably, during the soldering process, the upper clamping device, the lower clamping device, the transducer, and the cleaving nozzle move to the top of the substrate. The upper clamping device and the lower clamping device release the wire, and the cleaving nozzle moves the metal solder ball downwards onto the substrate and presses the metal solder ball onto the substrate. Then, the transducer is activated to solder the metal solder ball onto the substrate.

[0015] Preferably, when drawing a vertical arc, the lower clamping device, the cleaving ceramic nozzle, and the transducer all move upward so that the wire leaves a long tail of a set length at the tip of the cleaving ceramic nozzle, and the ablation notch on the long tail forms a vertical arc between it and the metal solder ball.

[0016] Preferably, when leaving a new wire tail, the upper clamping device loosens the wire, the lower clamping device clamps the wire, and the lower clamping device, transducer, and cleaver nozzle all move upward to pull the long wire tail upward. After being stressed, the long wire tail breaks from the ablation notch, so that the metal solder ball and vertical arc stand up and are fixed on the substrate. The broken long wire tail forms a new wire tail.

[0017] A vertical wire arc forming device for a fully automatic wire bonding machine includes, from top to bottom, an upper clamping device, a lower clamping device, a transducer, a cleaving ceramic nozzle, and a substrate, and further includes an electric discharge ball device and a laser located on both sides of the cleaving ceramic nozzle.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The wire arc notch obtained by this method is not produced by pressing the wire with the ceramic nozzle and the welding position, but by using a high-energy laser beam generated by a laser to directly ablate the notch on the wire. Therefore, the quality and usage of the ceramic nozzle will not affect the formation of the wire notch. 2. The wire notch formation process does not involve wire bending, requires little space to form the wire notch, is suitable for wafer pads of various specifications, and the overall verticality of the wire is high, without any bending or tilting of the wire neck, resulting in good vertical wire quality. 3. This method does not require secondary welding and can directly form a vertical arc after one welding, resulting in high arc welding efficiency. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of this application; Figure 2 This is a schematic diagram of the device in this application; Figure 3 This is a diagram showing the end of the line; Figure 4 This is a schematic diagram of the preparation process for laser notching; Figure 5 This is a schematic diagram showing the state of a fixed laser notch being created; Figure 6 This is a schematic diagram illustrating the formation of an ablation notch; Figure 7 This is a diagram illustrating the take-up process; Figure 8 This is a schematic diagram of the formation of the burnt ball tail; Figure 9 This is a diagram of a burnt ball; Figure 10 This is a schematic diagram of welding ball-mounting. Figure 11 This is a schematic diagram of drawing a vertical arc; Figure 12 This is a schematic diagram of leaving a new line tail.

[0020] In the diagram: 1. Wire; 101. Wire tail; 102. Ablation notch; 103. Metal solder ball; 104. Burned ball wire tail; 105. Long wire tail; 106. Vertical wire arc; 2. Upper clamping device; 3. Lower clamping device; 4. Transducer; 5. Discharge burning ball device; 6. Ceramic nozzle; 7. Laser; 8. Substrate. Detailed Implementation

[0021] The present invention will now be further described with reference to the accompanying drawings.

[0022] First, the required length of wire tail for vertical arc welding is left. Then, the cleaver nozzle guides the wire to the laser focal point, and the laser emits a high-energy-density laser beam, irradiating the required vertical arc height in the wire. This causes the surface temperature of the material at the required vertical arc height to rise, resulting in melting, ablation, and evaporation, ultimately forming a notch at the wire tail, weakening the mechanical strength at that height. The wire is then retracted, shortening the wire tail height to the height of the weld ball. The discharge welding device is activated, rapidly melting the weld ball tail into a metal weld ball. The cleaver nozzle, carrying the metal ball, presses it against the substrate and applies pressure. Under the combined action of heating, ultrasonic waves, and pressure, the weld ball is welded and fixed to the substrate weld point, completing one weld. After the cleaver nozzle returns to its position above the substrate, the lead wire is clamped and pulled out, leaving a long wire tail to prepare for the next weld point.

[0023] like Figures 1 to 12 As shown, a method for forming a vertical arc in a fully automatic wire bonding machine includes the following steps: Line tail: Extend a section of wire 1 from the ceramic nozzle 6 to form line tail 101; Fixed laser notch: The laser 7 is activated and irradiates the wire 1 at the focal point, causing the part of the wire 1 irradiated by the laser to melt, ablate, and evaporate, finally forming an ablation notch 102 on the wire 1, reducing the mechanical strength at that location; Take-up: Retract a portion of the wire 1, including the part weakened by laser ablation, into the cleaver nozzle 6 to form a burnt ball wire tail 104. Burning ball: Start the discharge burning ball device 5 to generate a high-temperature electric arc, which quickly melts the burning ball tail 104 into a metal welding ball 103; Welding ball placement: The ceramic nozzle 6 of the wedge blade presses down on the substrate 8 with the metal welding ball 103 and applies pressure. Under the combined action of heating, ultrasonic waves and pressure, the metal welding ball 103 is welded and fixed on the welding point of the substrate 8. Vertical arc 106: The ceramic nozzle 6 moves vertically upward to a certain height, drawing a vertical arc 106 of a specified height on the substrate 8. Leave a new wire tail 101: The clamping device is activated, the wire arc is broken, leaving a metal solder ball and a vertical wire arc 106 on the substrate 8, and a new wire tail 101 is left at the cleaver ceramic nozzle 6 to prepare for the next solder joint.

[0024] like Figure 2As shown, a vertical wire arc forming device for a fully automatic wire bonding machine includes, from top to bottom, an upper clamping device 2, a lower clamping device 3, a transducer 4, and a cleaving ceramic nozzle 6. It also includes an electric discharge ball device 5 located to the left of the cleaving ceramic nozzle 6 and a laser 7 fixedly positioned to the right. The wire 1 passes through the upper clamping device 2, the lower clamping device 3, the transducer 4, and the cleaving ceramic nozzle 6. When both the upper clamping device 2 and the lower clamping device 3 are open, it can move freely up and down. The upper clamping device 2 is fixedly installed at a constant height. The lower clamping device 3, the transducer 4, and the cleaving ceramic nozzle 6 are moved up and down by a clamping device (not shown). The laser 7 is fixed at a distance to the right of the cleaving ceramic nozzle 6.

[0025] Specifically, such as Figure 3 As shown, when releasing the wire tail, the upper clamping device 2 releases the wire 1, and the lower clamping device 3 clamps the wire 1 and moves the wire 1 downward, so that the wire 1 passes through the transducer 4 and the tip of the chopping ceramic nozzle 6. Then the lower clamping device 3 opens and returns to its original height, so that the wire 1 extends out from the end of the chopping ceramic nozzle 6, leaving a wire tail 101 of a set length between the wire 1 and the end of the ceramic nozzle 6.

[0026] The wire tail 101 can be obtained after the previous welding.

[0027] like Figure 4 As shown, when fixing the laser notch, the head of the device moves the wire 1, the upper clamping device 2, the lower clamping device 3, the transducer 4, the discharge ball device 5 and the cleaving ceramic nozzle 6 toward the laser 7, close to the fixedly installed laser 7, so that the wire tail 101 stops at the laser focus position directly in front of the laser 7 in the direction of laser emission. like Figure 5 and Figure 6 As shown, the laser 7 starts working and emits a high-energy laser beam 701 forward. The laser beam 701 irradiates the wire 1 at the focal point, causing the part of the wire 1 irradiated by the laser to melt, ablate, and evaporate, finally forming an ablation notch 102 on the wire 1, reducing the mechanical strength at that location.

[0028] like Figure 7 As shown, when retracting the wire, the laser 7 stops working; the upper clamping device 2 clamps the wire 1, the lower clamping device 3 releases the wire 1, and the clamping head drives the lower clamping device 3, the transducer 4, and the cleaving ceramic nozzle 6 to move downwards, while the wire 1 moves upwards relative to each other inside the transducer 4 and the cleaving ceramic nozzle 6.

[0029] like Figure 8As shown, when the ceramic nozzle 6 descends to the specified height, the upper clamping device 2 releases the wire 1, and the lower clamping device 3 clamps the wire 1 and returns it to its original height, so that the wire 1 between the ceramic nozzle end (tip) of the ceramic nozzle 6 is shortened to form the burnt ball wire tail 104, and the height of the burnt ball wire tail 104 is raised to be consistent with the height of the electrode of the discharge burnt ball device 5.

[0030] like Figure 9 As shown, during the ball-burning process, the discharge ball-burning device 5 is activated. The discharge ball-burning device 5 has a high voltage, which causes the air between the discharge ball-burning device 5 and the wire 1 to be broken down by the high voltage, generating a high-temperature electric arc, which causes the metal at the end of the wire 1 to melt rapidly and cool to form a metal solder ball 103.

[0031] like Figure 10 As shown, during the soldering process, the solder ball moves to the left and above the substrate 8. The lower clamping device 3 releases the wire 1, and the lower clamping device 3, transducer 4, cleaver nozzle 6, and metal solder ball 103 move downward, so that the metal solder ball 103 contacts the upper surface of the substrate 8 and generates pressure. The transducer 4 starts to generate high-frequency mechanical vibration. Under the combined action of the transducer 4 and the cleaver nozzle 6, the metal solder ball 103 is soldered and fixed on the substrate 8.

[0032] like Figure 11 As shown, when the vertical arc is drawn, the upper clamping device 2 releases the wire 1, the lower clamping device 3 releases the wire 1, the lower clamping device 3, the transducer 4, and the chopping ceramic nozzle 6 are all raised upwards, so that a set long wire tail 105 is left between the wire 1 and the end of the ceramic nozzle of the chopping ceramic nozzle 6. The length of the long tail 105 is the length of the vertical arc 106 plus the length of the new tail 101.

[0033] like Figure 12 As shown, when leaving a new wire tail, the upper clamping device 2 releases the wire 1, and the lower clamping device 3 clamps the wire 1. Since the metal solder ball 103 is welded and fixed on the substrate 8, the lower clamping device 3, transducer 4, and cleaver nozzle 6 continue to rise vertically. The wire 1 is subjected to axial tension and breaks at the ablation notch 102. This causes the metal solder ball 103 and the vertical arc 106 to stand up and be fixed on the substrate 8, completing the welding of this weld point. At the same time, after the wire 1 breaks, a set length of wire 1 is left between it and the end of the cleaver nozzle 6 to form a new wire tail 101, preparing for the welding of the next weld point.

[0034] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for forming a vertical arc in a fully automatic wire bonding machine, characterized in that, Includes the following steps: Extend a section of wire (1) from the ceramic nozzle (6) to form a wire tail (101). Fixed laser notch: The laser (7) is turned on and irradiates the wire (1) at the focal point, causing the part of the wire (1) irradiated by the laser to melt, ablate and evaporate, and finally forming an ablation notch (102) on the wire (1) to reduce the mechanical strength at this position; Take-up: Take a portion of the wire (1) including the part weakened by laser ablation (101) back into the ceramic nozzle (6) to form a burnt ball wire tail (104). Burning ball: Start the discharge burning ball device (5) to generate a high temperature electric arc, and quickly melt the burning ball wire tail (104) into a metal welding ball (103). Welding ball: The ceramic nozzle (6) of the wedge presses down on the substrate (8) with the metal welding ball (103) and applies pressure. Under the combined action of heating, ultrasonic waves and pressure, the metal welding ball (103) is welded and fixed on the welding point of the substrate (8). Draw a vertical arc (106): The ceramic nozzle (6) moves vertically upward to a certain height and draws a vertical arc (106) of a specified height on the substrate (8). Leave a new wire tail (101): The clamping device is activated, the wire arc is broken, leaving a metal solder ball and a vertical wire arc (106) on the substrate (8), and a new wire tail (101) is left at the cleaver nozzle (6) to prepare for the next solder joint.

2. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 1, characterized in that, When releasing the wire tail, the upper clamping device (2) opens, the lower clamping device (3) clamps the wire (1) and drives the wire (1) downward through the transducer (4) and the tip of the cleaver ceramic nozzle (6). The wire (1) passes through the cleaver ceramic nozzle (6) for a certain length to form the wire tail (101).

3. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 1, characterized in that, When fixing the laser to make a notch, the lower clamping device (3) clamps and cooperates with the cleaver ceramic nozzle (6), driving the wire tail (101) to move to the focal position of the laser (7), and then the laser (7) is started to form an ablation notch (102) on the wire (1) by laser ablation.

4. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 1, characterized in that, When retracting the wire, the laser (7) stops working, the upper clamping device (2) clamps the wire (1), the lower clamping device (3) releases the wire (1), and the lower clamping device (3), transducer (4) and cleaver ceramic nozzle (6) all move downward to the set position. Then the upper clamping device (2) releases the wire (1), and the lower clamping device (3) clamps the wire (1) and drives the wire (1) to rise, so that the length of the wire tail (101) formed at the tip of the cleaver ceramic nozzle (6) is shortened to become the burnt ball wire tail (104), and at the same time the end of the burnt ball wire tail (104) is aligned with the height of the discharge burnt ball device (5).

5. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 1, characterized in that, During the ball-burning process, the discharge ball-burning device (5) is activated, causing the air between the discharge ball-burning device (5) and the wire (1) to be broken down by high voltage, generating a high-temperature electric arc, so that the metal at the end of the ball-burning wire (104) melts rapidly and cools to form a metal solder ball (103).

6. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 1, characterized in that, When welding the ball, the upper clamping device (2), the lower clamping device (3), the transducer (4) and the cleaver nozzle (6) move to the top of the substrate (8). The upper clamping device (2) and the lower clamping device (3) release the wire (1). The cleaver nozzle (6) drives the metal welding ball (103) to move down to the substrate (8) and presses the metal welding ball (103) onto the substrate (8). Then the transducer (4) starts to weld the metal welding ball (103) onto the substrate (8).

7. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 1, characterized in that, When the vertical arc (106) is drawn, the lower clamping device (3), the cleaver nozzle (6) and the transducer (4) all move upward so that the wire (1) leaves a long tail (105) of a set length at the tip of the cleaver nozzle (6), and the ablation notch (102) on the long tail (105) forms a vertical arc (106) between it and the metal solder ball (103).

8. The method for forming a vertical arc in a fully automatic wire bonding machine according to claim 7, characterized in that, When leaving a new wire tail (101), the upper clamping device (2) loosens the wire (1), and the lower clamping device (3) clamps the wire (1). The lower clamping device (3), the transducer (4), and the cleaver ceramic nozzle (6) all move upward, pulling the long wire tail (105) upward. After being stressed, the long wire tail (105) breaks from the ablation notch (102), so that the metal solder ball (103) and the vertical arc (106) stand up and are fixed on the substrate (8). The broken long wire tail (105) forms a new wire tail (101).

9. A vertical arc forming device for a fully automatic wire bonding machine, used in the vertical arc forming method of a fully automatic wire bonding machine as described in claim 1, characterized in that, The device includes, from top to bottom, a wire (1), an upper clamping device (2), a lower clamping device (3), a transducer (4), a cleaving ceramic nozzle (6), and a substrate (8), as well as a discharge burning ball device (5) located to the left of the cleaving ceramic nozzle (6) and a laser (7) fixed to the right.

Images