Chip bonding head

Abstract

The invention discloses a chip bonding head, and particularly relates to the technical field of chip manufacturing, the chip bonding head comprises a rotating assembly, an upper force control assembly, a height measurement assembly, a guide assembly and a lower force control assembly, a spring and a second suction nozzle are arranged in the lower force control assembly, the second suction nozzle is compressed and arranged at an upper connecting piece, and the spring is pressed at a step of the upper connecting piece. A middle hole of the lower force control assembly is connected with a first gas circuit of the main shaft, an inner hole of the end cover and a gas pipe of the hollow elastic body inner connector and used for chip adsorption, the gas circuits are independent of other gas circuits and do not affect other gas circuits, the accuracy of chip detection is guaranteed, and the position precision of chip bonding is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chip manufacturing, and specifically to a chip bonding head. Background Art

[0002] In the field of chip manufacturing, the bonding head is particularly important in the chip bonding process. The design of the bonding head directly affects the reliability and accuracy of chip packaging. If the size of the bonding head design is too large, it will require more space for the bonding head to move during operation, thereby increasing the size of the equipment. On the other hand, if the mass of the bonding head is relatively large, it will increase the difficulty of controlling the force control accuracy. In the process of chip packaging, it often involves the bonding of chips of various different sizes. Different sizes of chips require different bonding forces. To ensure the packaging quality, there are requirements for the bonding force that is compatible with large and small forces and high-precision force control for the bonding head. The size of the chip is getting smaller and smaller, and the requirement for the accuracy of chip placement is getting higher and higher. The chip adsorption air path design of the bonding head often causes the chip adsorption vacuum to be affected by other air paths, resulting in the failure of chip pickup detection and the deterioration of the accuracy of chip placement.

[0003] In the prior art, high-precision bonding heads mostly use air bearings as the spindle guide. This type of bearing needs to be supplied with high-pressure gas to ensure its sufficient air film stiffness to guarantee the accuracy during the movement process. In this design, the chip adsorption air path is mostly interconnected with the fixture adsorption air path and the air bearing air supply path, resulting in the chip adsorption vacuum being easily affected by other air paths, directly affecting the chip mounting accuracy. Summary of the Invention

[0004] The purpose of the present invention is to provide a chip bonding head to solve the technical problems such as the chip adsorption vacuum being easily affected by other air paths, the relatively low force control accuracy of the bonding head, and the excessive size of the equipment caused by the size of the bonding head as mentioned in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A chip bonding head includes: a rotating assembly, an upper force control assembly, a height measurement assembly, a guiding assembly, and a lower force control assembly. The upper force control assembly is provided with a hollow elastic body. Inside the hollow elastic body, there is a rotary joint and an air pipe. The hollow elastic body can be a corrugated pipe, with the upper end connected to the motor shaft and the lower end connected to the end cover. The hollow elastic body has the characteristics of high rotational stiffness and low Z-direction stiffness. When generating a compression amount, it can provide a linear pressure. At the same time, high-pressure gas can be introduced into it to generate a certain air pressure to increase the pressure provided by the upper force control assembly. Inside the guiding assembly, there is an air bearing and a main shaft. The air bearing is placed inside the bearing housing and locked to the housing by a nut. The main shaft is placed inside the inner hole of the air bearing, with the upper end connected to the end cover and the lower end connected to the first suction nozzle.

[0007] The main shaft has a first air passage and a second air passage. The first air passage is connected to the first suction nozzle below and the inner hole of the end cap. The second air passage is connected to the third air passage of the air bearing. The third air passage of the air bearing is connected to the fifth air passage of the bearing housing. The fourth air hole of the air bearing is connected to the sixth air passage of the housing. The housing is connected with an air pipe joint, and the air pipe joint is respectively connected to the fifth and sixth air passages.

[0008] A magnet is built in the lower end of the main shaft and can be used for the adsorption of the lower force control component.

[0009] A high-pressure air film is provided between the air bearing and the main shaft to support the high-precision movement of the main shaft. A high-pressure air film is provided between the air bearing and the end cap to support the end cap and ensure that it does not rub against the air bearing, ensuring the high-precision rotation of the main shaft. The lower force control component is provided with a first flat spring and a second flat spring. The suction head is fixed on the first and second flat springs through an intermediate member and an upper connecting member. The suction head, the intermediate member, and the upper connecting member all have intermediate through holes, and the series of through holes are connected to the second suction nozzle for chip adsorption.

[0010] The first and second flat springs have high rotational stiffness and extremely low Z-direction stiffness, ensuring that the suction head has no displacement in other directions during up and down movement and providing extremely low compression force.

[0011] The lower force control component is provided with a spring and a second suction nozzle. The second suction nozzle is compressed and placed at the upper connecting member, and the spring is pressed against the step of the upper connecting member. The middle hole of the lower force control component is connected to the first air passage of the main shaft, the inner hole of the end cap, and the air pipe of the inner joint of the hollow elastic body for chip adsorption. This air passage is independent of other air passages and does not affect each other with other air passages.

[0012] When the suction head contacts the substrate, as the compression amount increases, the end cap continuously moves upward with the main shaft, and the position detected by the height measurement sensor continuously changes. By monitoring this change, the position height of the current substrate can be obtained. By measuring the height of different positions of the substrate, the height of different positions of the substrate can be obtained.

[0013] Preferably, a motor is provided in the rotating assembly. The motor is a frameless torque motor. The stator of the motor is installed in the inner ring of the housing, and the rotor of the motor is installed on the motor shaft. Upper and lower bearings are provided on the motor shaft for positioning the motor shaft. The code disk is bonded to the code disk seat, and the code disk seat is located at the first step of the main shaft. The reading head mounting seat is located above the housing and is used for mounting the reading head. The rotation accuracy is ensured by the high-precision code disk and the reading head. The motor shaft is of a hollow structure, and the low-torque rotary joint is connected at the uppermost part for air passage connection.

[0014] Preferably, the height measurement component includes an end cap and a height measurement sensor. The end cap is connected to the main shaft and can move up and down and rotate with the main shaft. The height measurement sensor can detect the distance of the up-and-down movement of the end cap and its current position in real time. The end cap has upper and lower threads and a through hole in the center.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] The present invention adopts a frameless torque motor and a small high-precision code disk, which can reduce the size of the bonding head and the structural mass, and is beneficial to improving the force control accuracy; adopting the series connection mode of a hollow elastomer and a flat spring can provide a small bonding force and a large bonding force; using a height measurement sensor can measure the heights of different positions of the substrate, so as to construct height measurement compensation and improve the force control accuracy; the structural method of isolating the chip adsorption air path from other air paths can avoid the influence of other positive and negative pressures on the chip adsorption, ensure the accuracy of detecting the presence or absence of the chip, and improve the position accuracy of chip bonding. Description of the Drawings

[0017] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 is a sectional view of the overall structure of the present invention;

[0019] In the figure: 1, suction head; 2, intermediate piece; 3, upper connecting piece; 4, first flat spring; 5, second flat spring; 6, upper limit seat; 7, lower limit seat; 8, second suction nozzle; 9, spring; 10, first suction nozzle; 100, bonding head; 11, first air path; 110, rotating component; 12, second air path; 120, upper force control component; 13, third air path; 130, height measurement component; 14, first air pipe joint; 140, guiding component; 15, fourth air hole; 150, lower force control component; 16, main shaft; 17, air bearing; 18, second air pipe joint; 19, end cap; 20, first rotary joint; 21, housing; 22, hollow elastomer; 23, air pipe; 24, fifth air path; 25, sixth air path; 26, motor shaft; 27, lower bearing; 28, motor stator; 29, motor rotor; 30, upper bearing; 31, code disk seat; 32, code disk; 33, second rotary joint; 34, bearing housing. Detailed Embodiments

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings of the present invention. Obviously, the described embodiments of the present invention are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] Embodiment

[0022] Combined Figure 1 and Figure 2 The present invention will be further described below. A chip bonding head includes a rotating assembly 110, an upper force control assembly 120, a height measuring assembly 130, a guiding assembly 140, and a lower force control assembly 150.

[0023] The rotating assembly 110 is used to drive the hollow elastic body 22 to rotate the main shaft 16 and the lower force control assembly 150. The motor stator 28 is bonded to the inner ring of the housing 21, the motor rotor 29 is bonded to the step of the motor shaft 26, the motor shaft 26 is positioned by the upper bearing 30 and the lower bearing 27, the code disk seat 31 is located at the uppermost step of the motor shaft 26, and the code disk 32 is installed on the code disk seat. The code disk reading head is installed on the top of the housing 21. When the code disk 32 rotates, the reading head can read the current position of the code disk in real time, so as to confirm the rotation angle of the motor shaft 26. The motor shaft 26 has a through central hole for connecting the gas path of the second rotary joint 33 and the lower hollow elastic body 22. The motor used in the rotating assembly 110 is a frameless torque motor, which has the characteristics of small volume and large torque. Combined with the use of a small code disk 32, the structure is more compact and a smaller structural mass is obtained.

[0024] The hollow elastic body 22 has an internal thread structure at both ends and can be connected to the motor shaft 26 and the end cover 19 up and down. The first rotary joint 20 and the air pipe 23 are installed inside it. The hollow elastic body 22 has the characteristics of high rotational stiffness and low Z-direction stiffness. When high-pressure gas is filled into it through the second rotary joint 33, a large compression force can be generated. This compression force is related to the effective cross-sectional area of the hollow elastic body and the magnitude of the inflation pressure. Moreover, the hollow elastic body 22 itself has a certain axial stiffness, and a certain compression force will also be generated when the body is compressed. The internal joints, air pipes and internal chambers of the hollow elastic body 22 are completely isolated, and the gas path in the air pipe is not affected by the high-pressure gas.

[0025] The end cover 19 is used to connect the main shaft 16 and the hollow elastic body 22. The thin-walled circumference below the end cover 19 is placed inside the height measuring sensor of the height measuring assembly 130, and the height measuring sensor can detect the position of the end cover 19 in the Z direction. When the main shaft 16 is pressed by the substrate and moves upward, the end cover 19 moves upward with the main shaft 16 and generates a displacement. At this time, the height measuring sensor will sense the movement of the end cover and monitor its position change in real time. The inner hole of the end cover 19 is connected to the upper first rotary joint 20 and is also connected to the first air path 11 of the main shaft.

[0026] The guiding component 140 is used to ensure the high-precision movement of the main shaft 16. The air bearing 17 is fixed on the bearing housing 34 by a nut. The outer circle of the main shaft 16 is matched with the inner hole of the air bearing 17. The main shaft 16 has a first air passage 11 connected to the first suction nozzle 10, and a second air passage 12 connected to the third air passage 13 of the air bearing 17. The third air passage 13 is communicated with the first air pipe joint 14. The first air pipe joint 14 is connected to a negative pressure. The vacuum comes to the upper part of the lower force control component 150 through the series-connected air passages, and tightly adsorbs the lower force control component 150 on the main shaft 16. The inner hole of the air bearing 17 has multiple rows of fine holes connected to the fourth air hole 15, and the fourth air hole is connected to the sixth air passage 25 of the bearing housing. The second air pipe joint 18 is filled with positive pressure gas, which enters the fitting clearance between the main shaft 16 and the air bearing 17, and the fitting plane between the main shaft 16 and the end cover 19 through the sixth air passage 25 and the fourth air hole 15, so as to reduce the friction between the end cover 19 and the main shaft 16, ensure that the rotation is not affected by large key forces, and ensure that the main shaft has no radial runout during the movement of the bonding head. The main shaft 16 also has magnets and positioning circles, which can be used for the adsorption and positioning of different fixtures.

[0027] The lower force control component 150 is mainly used for the control of small key forces. Among them, the suction head 1 and the intermediate piece 2 are clamped on the first flat spring 4, and the intermediate piece 2 and the upper connecting piece 3 are clamped on the second flat spring 5. The first and second flat springs are respectively fixed on the lower force control component housing by the lower limit seat 7 and the upper limit seat 6. The upper connecting piece 3 has a step located in the step groove of the upper limit seat 6, and the suction head 1 has a step located in the step groove of the lower limit seat 7, and the up and down movement stroke of the suction head in the Z direction is restricted by the two step grooves. The spring 9 presses above the step of the upper connecting piece 3 and has a certain compression force, so that the initial position of the suction head is at the lowest point in the Z direction. The second suction nozzle 8 is installed in the inner hole of the upper connecting piece and is used to connect the air passage. The first and second flat springs are extremely thin in thickness, have a high rotational height and an extremely low Z-direction stiffness, and can provide a very small key force within their Z-direction stroke.

[0028] Further, the rotation of this bonding head: Through the rotation of the frameless torque motor, the motor shaft 26 drives the end lower force control component 150 connected through the hollow elastomer 22, the end cover 19, and the main shaft 16 to rotate. The chip is adsorbed by the suction head 1. The inner hole of the suction head 1 is continuously connected upward to the vacuum pipe 23. The chip adsorption path is completely isolated from other air paths, ensuring that the chip transfer and bonding processes are not affected by other air paths, resulting in chip position deviation. The compression force of the flat spring in the lower force control component 150 has a linear relationship with the compression amount. The compression force of the hollow elastomer in the upper force control component 120 has a linear relationship with the compression amount and is linearly related to the air pressure introduced into it. Based on this linear relationship, through pressure calibration by the pressure sensor, the relationship between the accurate bonding force, the compression amount, and the air supply pressure can be obtained. When performing force control with a small bonding force, a certain air pressure is introduced into the hollow elastomer. At this time, the compression amount is mainly generated by the up and down movement of the flat spring, and the main shaft does not move in the Z direction. The flat spring has an extremely small stiffness and can provide an extremely small bonding force within its stroke. When performing force control with a large bonding force, a high pressure is introduced into the hollow elastomer. When the suction head 1 moves upward and contacts the upper limit seat 6 for positioning, it pushes the main shaft upward, thereby compressing the hollow elastomer to obtain a large bonding force. The above composite structure can be compatible with large and small bonding forces. In addition, since the bonding force is closely related to the compression amount, in order to ensure the accuracy of force control, the height fluctuations on the substrate surface cannot be ignored. The method for this bonding head to measure the height of the substrate bonding position using a height sensor is as follows: When the suction head contacts the substrate, as the compression amount increases, the end cover continuously moves upward with the main shaft, and the position detected by the height sensor continuously changes. By monitoring this change, the current substrate position height can be obtained. By measuring the height at different substrate positions, the heights of different positions on the substrate can be obtained. Based on the obtained height values, the actual compression amount during chip bonding at each position can be corrected to ensure that the actual compression amount is the desired compression amount, thereby ensuring that the bonding force is closer to the desired force and improving the accuracy of the bonding force.

Claims

1. A chip bonding head, characterized in that, Including rotating assembly, upper force control assembly, height measuring assembly, guiding assembly, lower force control assembly, The upper force control component is provided with a hollow elastic body, wherein a swivel joint and an air pipe are arranged in the hollow elastic body, and the hollow elastic body can be a bellows, the upper end of which is connected to the motor shaft, and the lower end is connected to the end cover; The guide assembly is provided with an air bearing and a spindle, the air bearing is placed in a bearing housing and is locked on the housing by a nut, the spindle is placed in an inner hole of the air bearing, the upper end is connected to the end cover, and the lower end is connected to the first suction nozzle; The lower force control component is provided with a first planar spring and a second planar spring, the suction head is fixed on the first and second planar springs through an intermediate piece and an upper connecting piece, the suction head, the intermediate piece and the upper connecting piece all have an intermediate through hole, the through holes in series are connected to the second suction nozzle, the lower force control component is provided with a spring and a second suction nozzle, the second suction nozzle is compressed and placed on the upper connecting piece, the spring is pressed on the step of the upper connecting piece, the middle hole of the lower force control component is connected to the first air path of the main shaft, the inner hole of the end cover, and the air pipe of the hollow elastic body joint.

2. The chip bonding head according to claim 1, characterized in that, The main shaft has a first air path and a second air path, the first air path connects the first suction nozzle below and the inner hole of the end cover, the second air path is connected to the third air path of the air bearing, the third air path of the air bearing is connected to the fifth air path of the bearing housing, the fourth air hole of the air bearing is connected to the sixth air path of the housing, the housing is connected to an air pipe joint, and the air pipe joint is respectively connected to the fifth and sixth air paths.

3. The chip bonding head according to claim 2, wherein, A magnet for adsorbing the lower force control component is built into the lower end of the main shaft, a high-pressure air film for supporting the main shaft is provided between the air bearing and the main shaft, and a high-pressure air film for supporting the end cover is provided between the air bearing and the end cover.

4. A chip bonding head according to claim 1, characterized in that, A motor is provided in the rotating assembly, and the motor is a frameless torque motor. The motor stator is mounted on the inner ring of the outer shell, and the motor rotor is mounted on the motor shaft. The motor shaft is provided with upper bearings and lower bearings. The code disc is bonded to the code disc seat, and the code disc seat is located at the first step of the main shaft. The reading head mounting seat is located above the outer shell.

5. The chip bonding head according to claim 4, characterized in that, The motor shaft is a hollow structure, and a low-torque rotary joint is connected at the top for gas line connection.

6. The chip bonding head according to claim 1, characterized in that, The height measuring component comprises an end cover and a height measuring sensor. The end cover is connected to the main shaft. The end cover has upper and lower threads and a through hole in the center.

Images