A method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine

Abstract

The present invention provides a method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine, comprising the following steps: S1: using tweezers to pull the aluminum wire out of the aluminum wire feeding tube; S2: automatically pressing the welding head down to an appropriate position; S3: controlling the welding head to gradually move downward again until the splitting knife cuts the aluminum wire and stops; S4: the downward amount of the splitting knife at this time is the cutting depth. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine described in the present invention is based on the preset height of the displacement sensor, and then moves downward on this basis, and finally cuts the aluminum wire as the goal, and obtains the cutting depth relative to the downward fixed depth for cutting, which has higher cutting effect and reliability, and avoids the problem of not being able to cut or damaging the wafer.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor packaging and testing, and in particular to a method for accurately calibrating a cutting blade depth of a power semiconductor wire bonding machine. Background Art

[0002] The production process of power semiconductor products is divided into three processes: design, manufacturing, and packaging and testing. In the packaging and testing production link, the main processing techniques are divided into Die Bond (chip welding) and Wire Bond (wire bonding). The main purpose of wire bonding is to use an ultrasonic mechanism to weld thick aluminum wire (100um-500um) to the welding point between the chip and the lead frame under the action of external force. In the wire cutting process, the wire cutting depth is an important process parameter.

[0003] The traditional cutting depth is a fixed value, which is not a calibration value obtained based on the actual cutting of the aluminum wire. If the cutting is too deep, it will cause damage to the wafer surface. If the cutting is too shallow, the aluminum wire will not be cut continuously. In order to solve the above problems, we proposed a method for accurately calibrating the cutting knife depth of the power semiconductor wire bonding machine. Summary of the invention

[0004] The purpose of the present invention is to provide a method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine. The actual cutting of the aluminum wire is taken as the final goal, and the calibrated cutting depth is used for cutting relative to the fixed depth of the downward direction. The cutting effect and reliability are higher, and the problem of not being able to cut or damaging the wafer is avoided.

[0005] The embodiment of the present invention is achieved as follows:

[0006] An embodiment of the present invention provides a method for accurately calibrating a cutting depth of a power semiconductor wire bonding machine, comprising the following steps:

[0007] S1: Use tweezers to pull the aluminum wire out of the aluminum wire feeding tube;

[0008] S2: Automatically press the welding head down to the appropriate position;

[0009] S3: Control the welding head to move downward gradually again until the cutter cuts the aluminum wire and stops;

[0010] S4: The downward movement of the cutter at this time is the cutting depth.

[0011] Optionally, the welding head includes a displacement sensor, a down pressure generator, an ultrasonic transducer, an aluminum wire feeding tube, a chopper, and a cutter, wherein the displacement sensor and the down pressure generator are hard-connected to the driving arm as a whole, and the ultrasonic transducer, the aluminum wire feeding tube, the chopper, and the cutter are soft-connected to the driving arm as a whole, and can move up and down slightly relative to the displacement sensor and the down pressure generator.

[0012] Optionally, in step S1, the length of the aluminum wire pulled out from the aluminum wire feeding tube is three to five millimeters, and the pulled-out aluminum wire passes through the groove of the splitting knife head and remains perpendicular to the splitting knife.

[0013] Optionally, in the process of pressing down the welding head in step S2, a displacement sensor is used to measure distance, and the displacement sensor is set with a calibrated depth and a predetermined downward position, and the displacement sensor stops after reaching the predetermined position.

[0014] Optionally, after the displacement sensor moves to a predetermined position and stops, the chopper presses the aluminum wire onto the welding interface.

[0015] Optionally, the displacement sensor can detect the relative positions of the ultrasonic transducer, the aluminum wire feeding tube, the splitting knife, the cutting knife and the overall relative displacement sensor and the downforce generator.

[0016] Optionally, the cutter is installed close to the splitting knife but not in contact with it, the aluminum wire feeding tube is installed close to the other side of the splitting knife but not in contact with it, and the aluminum wire passes through the aluminum wire feeding tube and is placed directly below the end of the splitting knife.

[0017] Optionally, the ultrasonic transducer and the splitting knife are tightly and fixedly connected, the splitting knife passes through one end of the ultrasonic transducer, and the ultrasonic transducer is equipped with a matching ultrasonic generator.

[0018] Optionally, during the operation of the welding head, the downward pressure generator remains in a disabled state throughout the entire process.

[0019] Optionally, the downward movement of the cutter in step S4 is based on a preset height of the displacement sensor, and the cutter moves downward on this basis, ultimately aiming to cut the aluminum wire and obtain the cutting depth.

[0020] The beneficial effects of the embodiments of the present invention include: the embodiments of the present invention provide a method for accurately calibrating the cutting knife depth of a power semiconductor wire bonding machine, the welding head is automatically pressed down to the calibrated depth set by the displacement sensor and the predetermined downward position, the splitting knife and the displacement sensor stop after running to the predetermined position, the aluminum wire is pressed on the welding interface, and then the welding head is controlled to move downward step by step again until the cutter cuts the aluminum wire and stops, the downward amount of the cutter is based on the preset height of the displacement sensor, and the downward movement is performed on this basis, and finally the cutting depth is obtained with the goal of cutting the aluminum wire, and the calibrated cutting depth is used for cutting relative to the downward fixed depth with the actual cutting of the aluminum wire as the final goal, the cutting effect and reliability are higher, and the problem of not being able to cut or damaging the wafer is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 The present invention is a schematic diagram of a welding head structure of a power semiconductor wire bonding machine in a wire cutting process.

[0023] Icons: 1. Displacement sensor; 2. Downward pressure generator; 3. Ultrasonic transducer; 4. Aluminum wire feeding tube; 5. Chopping knife; 6. Cutter. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] like Figure 1 As shown, an embodiment of the present invention provides a method for accurately calibrating the depth of a cutter 6 of a power semiconductor wire bonding machine, comprising the following steps:

[0029] S1: Use tweezers to pull out the aluminum wire from the aluminum wire feeding tube 4. The length of the aluminum wire pulled out from the aluminum wire feeding tube 4 is three to five millimeters. The pulled-out aluminum wire passes through the groove on the head of the splitting knife 5 and remains perpendicular to the splitting knife 5.

[0030] S2: The welding head is automatically pressed down to an appropriate position. During the pressing process of the welding head, the displacement sensor 1 is used to measure the distance. The displacement sensor 1 is set with a calibrated depth and a predetermined downward position. The displacement sensor 1 stops after running to the predetermined position. After the displacement sensor 1 moves to the predetermined position and stops, the chopper 5 presses the aluminum wire onto the welding interface.

[0031] S3: Control the welding head to move downward gradually again until the cutter 6 cuts the aluminum wire and stops;

[0032] S4: At this time, the downward distance of the cutter is the tangent depth. The downward distance of the cutter is based on the preset height of the displacement sensor 1. On this basis, the cutter moves downward, and finally cuts the aluminum wire to obtain the tangent depth.

[0033] The welding head is automatically pressed down to the calibrated depth and the predetermined downward position set by the displacement sensor 1. The splitter 5 and the displacement sensor 1 stop after running to the predetermined position, pressing the aluminum wire on the welding interface, and then the welding head is controlled to move downward step by step again until the cutter 6 cuts the aluminum wire and stops. The downward amount of the cutter 6 is based on the preset height of the displacement sensor 1, and the downward movement is carried out on this basis. The final goal is to cut the aluminum wire and obtain the tangent depth. The actual cutting of the aluminum wire is the final goal. The calibrated cutting depth is relative to the downward fixed depth for tangent, and the tangent effect and reliability are higher, avoiding the problem of not being able to cut or damaging the wafer.

[0034] As an embodiment of the present invention, the welding head includes a displacement sensor 1, a down pressure generator 2, an ultrasonic transducer 3, an aluminum wire feeding tube 4, a splitting knife 5, and a cutting knife 6, wherein the displacement sensor 1 and the down pressure generator 2 are hard-connected to the driving arm as a whole, and the ultrasonic transducer 3, the aluminum wire feeding tube 4, the splitting knife 5, and the cutting knife 6 are soft-connected to the driving arm as a whole, and can move up and down slightly relative to the displacement sensor 1 and the down pressure generator 2.

[0035] As an embodiment of the present invention, the displacement sensor 1 can detect the relative positions of the ultrasonic transducer 3 , the aluminum wire feeding tube 4 , the splitting knife 5 , and the cutting knife 6 relative to the displacement sensor 1 and the down force generator 2 .

[0036] As an embodiment of the present invention, the cutter 6 is installed close to the splitting knife 5 but not in contact with it, the aluminum wire feeding tube 4 is installed close to the other side of the splitting knife 5 but not in contact with it, and the aluminum wire passes through the aluminum wire feeding tube 4 and is placed directly below the end of the splitting knife 5.

[0037] As an implementation mode of the present invention, the ultrasonic transducer 3 and the splitting knife 5 are tightly and fixedly connected, the splitting knife 5 passes through one end of the ultrasonic transducer 3, and the ultrasonic transducer 3 is adapted with a matching ultrasonic generator.

[0038] As an implementation mode of the present invention, during the operation of the welding head, the downward pressure generator remains in a disabled state throughout the entire process.

[0039] It should be noted that the present invention is a method for accurately calibrating the cutting knife depth of a power semiconductor lead bonding machine. Tweezers are used to pull out the aluminum wire from the aluminum wire feeding tube by three to five millimeters. The pulled-out aluminum wire passes through the groove of the splitting knife head and remains vertical to the splitting knife 5. The welding head is automatically pressed down to the calibrated depth and the predetermined downward position set by the displacement sensor. The splitting knife and the displacement sensor stop after running to the predetermined position, and the aluminum wire is pressed on the welding interface. Then the welding head is controlled to move downward step by step again until the cutter cuts the aluminum wire and stops. During the operation of the welding head, the downward pressure generator remains disabled throughout the whole process. The downward amount of the cutter is based on the preset height of the displacement sensor, and the downward movement is performed on this basis. Finally, the cutting depth is obtained with the goal of cutting the aluminum wire. The actual cutting of the aluminum wire is the final goal. The calibrated cutting depth is relative to the downward fixed depth for cutting. The cutting effect and reliability are higher, avoiding the problem of not being able to cut or damaging the wafer.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine, characterized in that: The following steps are involved: S1: Use tweezers to pull the aluminum wire out of the aluminum wire feeding tube (4); S2: The welding head is automatically pressed down to an appropriate position; the welding head comprises a displacement sensor (1), a downward pressure generator (2), an ultrasonic transducer (3), an aluminum wire feeding tube (4), a splitter (5), and a cutter (6), wherein the displacement sensor (1) and the downward pressure generator (2) are a whole and are hard-connected to the driving arm, and the ultrasonic transducer (3), the aluminum wire feeding tube (4), the splitter (5), and the cutter (6) are a whole and are soft-connected to the driving arm, and can move up and down with a small amplitude relative to the displacement sensor (1) and the downward pressure generator (2). S3: Control the welding head to move downward gradually again until the cutter (6) cuts the aluminum wire and stops; S4: The downward movement of the cutter at this time is the cutting depth.

2. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: In the step S1, the length of the aluminum wire pulled out from the aluminum wire feeding tube (4) is three to five millimeters. The pulled out aluminum wire passes through the groove of the head of the splitting knife (5) and remains perpendicular to the splitting knife (5).

3. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: In the step S2, the distance is measured by a displacement sensor (1) during the downward pressing process of the welding head. The displacement sensor (1) is set with a calibrated depth and a predetermined downward position. The displacement sensor (1) stops after running to the predetermined position.

4. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 3, characterized in that: After the displacement sensor (1) moves to a predetermined position and stops, the chopper (5) presses the aluminum wire onto the welding interface.

5. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: The displacement sensor (1) is capable of detecting the relative positions of the ultrasonic transducer (3), the aluminum wire feeding tube (4), the splitting knife (5), and the cutting knife (6) as a whole relative to the displacement sensor (1) and the downward pressure generator (2).

6. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: The cutting knife (6) is installed close to the splitting knife (5) but not in contact with it, and the aluminum wire feeding tube (4) is installed close to the other side of the splitting knife (5) but not in contact with it. The aluminum wire passes through the aluminum wire feeding tube (4) and is placed just below the end of the splitting knife (5).

7. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: The ultrasonic transducer (3) and the splitting knife (5) are tightly and fixedly connected, the splitting knife (5) passes through one end of the ultrasonic transducer (3), and the ultrasonic transducer (3) is equipped with a matching ultrasonic generator.

8. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: During the operation of the welding head, the downward pressure generator remains in a disabled state throughout the entire process.

9. The method for accurately calibrating the cutting depth of a power semiconductor wire bonding machine according to claim 1, characterized in that: The downward movement of the cutter in step S4 is based on the preset height of the displacement sensor (1), and the downward movement is performed on this basis, with the ultimate goal of cutting the aluminum wire and obtaining the cutting depth.

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