Chip surface mounting structure and surface mounting method
By setting up a picking device and a heating device on the mounting frame of the robotic arm's moving end, the chip is rapidly heated using an alternating magnetic field and heat-conducting pillars. Combined with cooling and buffering devices, the problems of chip cracking and low efficiency under the track heating method are solved, achieving efficient and stable chip mounting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-09
- Publication Date
- 2026-04-10
AI Technical Summary
In existing technologies, the track heating method keeps the substrate and the chip under heat during multilayer mounting. The glass transition of the DAF film can easily cause chip cracking, resulting in poor heat conduction efficiency and affecting chip mounting efficiency.
The chip is rapidly heated by using a pick-up device and a heating device on the mounting frame of the robotic arm's moving end. The alternating magnetic field generated by the pulse heating ring and the heat-conducting column convert electrical energy into heat energy, and the chip is rapidly cooled by a cooling device. Combined with cylinder buffering and angle fine adjustment, the chip can be efficiently mounted.
It reduces chip placement time, improves placement efficiency, reduces the risk of chip cracking, and enhances the stability and accuracy of the equipment.
Smart Images
Figure CN121843559A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor chip technology, and in particular to a chip mounting structure and mounting method. Background Technology
[0002] DAF (Digital Embedded Surface Mount) technology is an advanced technology that is crucial in modern semiconductor packaging, especially in 3D packaging and ultra-thin chip applications.
[0003] The relevant DAF heating and mounting process uses a substrate heating method, namely the track heating method. After the chip is picked up from the positioning platform by the pick-up device, it is placed on the substrate. The heating track continuously supplies heat, so that the track support plate heats the substrate, and the heat is conducted from the substrate to the chip from bottom to top.
[0004] In the above-mentioned track heating method, during multilayer mounting, the substrate and the mounted chip are constantly heated throughout the entire process, and the DAF film is also constantly in a glassy state, which can easily lead to chip cracking. At the same time, the heat needs to be conducted upward through the underlying chip that has already been mounted. The more layers stacked, the worse the heat conduction efficiency becomes, which affects the heat absorption efficiency of the DAF of the mounted chip, resulting in low chip mounting efficiency. Summary of the Invention
[0005] To address the issue of track heating in related technologies, where the substrate and mounted chips remain heated throughout the multilayer mounting process, and the DAF film remains in a glassy state, potentially leading to chip cracking, and requiring the heat to be conducted upwards through the already mounted chips, the more layers stacked, the worse the heat conduction efficiency becomes, affecting the heat absorption efficiency of the DAF film on the mounted chips and resulting in low chip mounting efficiency, this application provides a chip mounting structure with the following technical solution: a mounting frame disposed at the moving end of a robotic arm, a connecting frame disposed on the mounting frame, a picking device disposed on the connecting frame for picking up chips, and a heating device disposed on the connecting frame for heating the picking device.
[0006] In one specific implementation scheme, the material handling device includes a material handling plate disposed on a connecting frame, the material handling plate having a plurality of adsorption holes, and an adsorption channel communicating with the plurality of adsorption holes within the material handling plate, the adsorption channel being connected to a vacuum adsorption device.
[0007] In one specific implementation, the heating device includes a magnetic field unit for generating an alternating magnetic field and a heat-conducting unit for outputting the heat generated by the magnetic field. The magnetic field unit includes a pulse heating ring disposed on a connecting frame, and the heat-conducting unit includes a heat-conducting column disposed on the connecting frame. The heat-conducting column is located on the inner edge of the pulse heating ring, and the material taking plate is disposed on the heat-conducting column.
[0008] In one specific implementation, the connecting frame is provided with a cooling device for cooling the material handling device. The cooling device includes a cooling ring disposed on the connecting frame, and a cooling channel for circulating coolant is opened in the cooling ring. The pulse heating ring is located between the cooling ring and the material handling plate. The mounting frame is provided with a circulation unit for driving the coolant to circulate in the cooling channel.
[0009] In one specific implementation, the mounting bracket is provided with a vertically arranged cylinder, the output end of the cylinder is provided with a connecting rod, and the connecting bracket is located at the end of the connecting rod away from the mounting bracket.
[0010] In one specific implementation, the connecting frame is rotatably connected to the mounting frame, the mounting frame is provided with a drive motor, the output end of the drive motor is provided with a first gear, the connecting frame is provided with a connecting sleeve, and the outer edge of the connecting sleeve is fixedly fitted with a second gear that matches the first gear, and the first gear and the second gear mesh with each other.
[0011] In one specific implementation, the tooth width of the first gear is greater than the tooth width of the second gear.
[0012] In one specific implementation, the connecting frame is provided with a heat insulation plate, the connecting sleeve is disposed on the heat insulation plate, and the heat insulation plate is located on the side of the heating device away from the material handling device.
[0013] In one specific implementation scheme, a chip mounting method based on the above-described chip mounting structure is characterized in that the method includes: The robotic arm moves the mounting frame to the position corresponding to the chip on the positioning platform, activates the vacuum adsorption equipment, and adsorbs the chip onto the picking plate through the adsorption holes. The robotic arm then moves the chip toward the substrate. As the chip moves toward the substrate, the pulse heating ring is energized to generate an alternating magnetic field. The heat-conducting pillar converts the magnetic energy into heat energy, which is then transferred from the heat-conducting pillar to the chip on the pick-up board and the DAF film. The robotic arm moves the heated chip to the target mounting position and places the chip on the target mounting position; The cylinder is activated, providing a preset amount of air to the cylinder to apply a preset pressure to the chip; the vacuum adsorption device is turned off to release the adsorption of the chip, and the chip is placed on the target mounting position on the substrate. The robot arm moves the unloaded mounting frame toward the positioning platform to reset. During the process of the mounting frame resetting from the base plate toward the positioning platform, the circulation unit is activated to drive the coolant to circulate in the cooling channel to cool the connecting frame and the material picking plate.
[0014] In one specific implementation scheme, a chip mounting method based on the above-mentioned chip mounting structure is characterized in that the method further includes: when the chip mounting structure is completely shut down, a vacuum is drawn inside the cylinder to drive the connecting rod to extend and retract, so that the connecting rod provides tension to the connecting frame.
[0015] In summary, this application has the following beneficial technical effects: when chip mounting is required, the robotic arm drives the mounting bracket to move to the position corresponding to the chip on the positioning platform, and starts the pick-up device to pick up the chip. During the process of the robotic arm moving the chip toward the substrate, the heating device is started to heat the chip on the pick-up device. The preheating of the DAF film and the glass state transition are completed before the chip reaches the mounting height, which greatly reduces the chip mounting time and improves the chip mounting efficiency. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application.
[0017] Figure 2 This is a schematic diagram illustrating the structure of the cylinder in Embodiment 1 of this application.
[0018] Figure 3 This is a cross-sectional schematic diagram of the heat-conducting column in Embodiment 1 of this application.
[0019] Reference numerals: 1. Mounting bracket; 2. Connecting bracket; 3. Material picking plate; 4. Adsorption hole; 5. Pulse heating ring; 6. Heat guiding column; 7. Cooling ring; 8. Cylinder; 9. Connecting rod; 10. Drive motor; 11. Connecting sleeve; 12. First gear; 13. Second gear; 14. Heat insulation plate. Detailed Implementation
[0020] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.
[0021] Example 1 Embodiment 1 of this application discloses a chip patch structure.
[0022] Reference Figure 1 , Figure 2 and Figure 3 The chip mounting structure includes a mounting frame 1 set at the moving end of the robot arm, a connecting frame 2 mounted on the mounting frame 1, a picking device for picking up chips on the connecting frame 2, and a heating device for heating the picking device on the connecting frame 2.
[0023] Therefore, when chip mounting is required, the robotic arm moves the mounting bracket 1 to the position corresponding to the chip on the positioning platform, and starts the pick-up device to pick up the chip. As the robotic arm moves the chip towards the substrate, the heating device is activated to heat the chip on the pick-up device. This preheating of the DAF film and the glass transition are completed before the chip reaches the mounting height, greatly reducing chip mounting time and improving chip mounting efficiency. Compared to the mounting method in related technologies where the heating track continuously heats the substrate, the traditional track's substrate heating area temperature is 200°C. Long-term operation can cause thermal drift in the track mounting and the precision vision system due to the radiation from the temperature. In this embodiment, the chip on the pick-up device is heated by the heating device, and the substrate only needs to be kept in a low-temperature preheating state (approximately 60°C). This reduces the possibility of chip cracking caused by continuous track heating. The required temperature throughout the mounting process is directly applied to the chip being mounted by the heating device and directly conducted to the DAF film through the chip. This results in higher heat conduction efficiency and improved long-term stability of the equipment.
[0024] Reference Figure 1 , Figure 2 and Figure 3 The picking device includes a picking plate 3 mounted on a connecting frame 2. The picking plate 3 has several adsorption holes 4 and an adsorption channel communicating with the adsorption holes 4. This adsorption channel is connected to a vacuum adsorption device in related technologies. Therefore, when a chip needs to be picked up, the vacuum adsorption device is activated, and the chip is adsorbed onto the picking plate 3 through the adsorption channel and the adsorption holes 4. In this embodiment, the picking plate 3 is made of a material with an ultra-low coefficient of thermal expansion, ensuring a surface flatness of 2µm even when the temperature of the picking plate 3 reaches 200℃, such as Kova alloy or Kova alloy.
[0025] Reference Figure 1 , Figure 2 and Figure 3 The heating device includes a magnetic field unit for generating an alternating magnetic field and a heat-conducting unit for outputting the heat generated by the magnetic field. The magnetic field unit includes a pulse heating ring 5 disposed on a connecting frame 2. In this embodiment, several pulse heating rings 5 are stacked vertically and coaxially arranged. The heat-conducting unit includes a heat-conducting column 6 disposed on the connecting frame 2. The heat-conducting column 6 is located on the inner edge of the pulse heating ring 5 and is made of metal. The pick-up plate 3 is disposed on the heat-conducting column 6. The heating device can realize high-frequency temperature conversion according to the on-site conditions. In this embodiment, the chip picking and chip mounting processes can be set with different temperatures or rates. For example, when mounting the chip, the heating device is controlled to heat up, and the heating rate is set to 200℃ / sec; when picking up the chip, the heating device is controlled to cool down, and the cooling efficiency is set to 120℃ / sec.
[0026] Therefore, when the pulse heating ring 5 is powered on, a high-frequency alternating magnetic field is instantly generated in the space around it. This alternating magnetic field passes through the heat-conducting column 6 located on its inner edge and generates eddy currents. When the eddy currents flow, they encounter resistance, thus directly converting electrical energy into heat energy, causing the heat-conducting column 6 to heat up rapidly. The heat-conducting column 6 transfers heat to the chip on the feeding plate 3, achieving rapid heating of the chip. The heating speed can reach 200℃ / sec.
[0027] Reference Figure 1 , Figure 2 and Figure 3 The connecting frame 2 is provided with a cooling device for cooling the material taking device. The cooling device includes a cooling ring 7 installed on the connecting frame 2. A cooling channel for circulating coolant is opened in the cooling ring 7. A pulse heating ring 5 is located between the cooling ring 7 and the material taking plate 3. The mounting frame 1 is provided with a circulation unit for driving the coolant to circulate in the cooling channel. In this embodiment, the circulation unit can be a circulation pump.
[0028] Therefore, when the mounting bracket 1 needs to be cooled during the process of resetting from the substrate to the positioning platform, the circulating pump drives the coolant to flow out from the external storage tank and into the cooling channel of the cooling ring 7. The coolant absorbs heat through heat exchange during the flow process, thereby reducing the temperature of the connecting bracket 2 and the picking plate 3. High-speed cooling is achieved by controlling the gas-liquid conversion of the coolant and the microchannel, which facilitates the subsequent low-temperature picking of the chip. In this embodiment, the cooling efficiency is 200℃ / sec.
[0029] Reference Figure 1 , Figure 2 and Figure 3 A vertically positioned cylinder 8 is mounted on the mounting bracket 1. A connecting rod 9 is located at the output end of cylinder 8, and a connecting frame 2 is installed at the end of the connecting rod 9 facing away from the mounting bracket 1. When the chip is placed at the target mounting position on the substrate, the reaction force generated at the contact point at the instant the bottom surface of the chip contacts the substrate pushes the connecting rod 9 to slowly contract against the air pressure inside cylinder 8. This process absorbs the downward impact kinetic energy, providing a buffering effect and greatly protecting the chip and the substrate. After the connecting rod 9 contracts and buffers the initial impact, the control system maintains or adjusts the air pressure inside the cylinder 8, providing a preset air volume to provide a preset pressure to the chip, thus achieving precise control of the mounting pressure.
[0030] Furthermore, when the chip mounting structure is completely shut down, the control system evacuates the cylinder 8 to drive the connecting rod 9 to extend or retract, thus providing tension on the connecting frame 2 and reducing the load on the connecting frame 2 when the chip mounting structure is shut down. In related technologies, a rail heating method is used, and the chip pick-up device only has a suction head, resulting in a lightweight overall structure. However, in this embodiment, the chip pick-up device integrates heating and cooling devices, leading to a heavier overall weight. To balance this additional weight, when the chip mounting structure is completely shut down, the control system evacuates the cylinder 8 to provide additional tension on the connecting rod 9, reducing mechanical deformation caused by additional gravity and minimizing the possibility of misalignment affecting accuracy.
[0031] Reference Figure 1 , Figure 2 and Figure 3 A heat insulation plate 14 is provided on the connecting frame 2, and the connecting sleeve 11 is provided on the heat insulation plate 14. The heat insulation plate 14 is located on the side of the heating device away from the material taking device. In this embodiment, the heat insulation plate 14 is located between the second gear 13 and the cooling ring 7. The heat insulation plate 14 plays a role in isolating the heat source, reducing the possibility of heat being continuously transferred to the second gear 13 and thus affecting the precision transmission, and facilitating the stable operation of the transmission components.
[0032] Reference Figure 1 , Figure 2 and Figure 3 The connecting frame 2 is rotatably connected to the mounting frame 1. A drive motor 10 is mounted on the mounting frame 1, and a first gear 12 is mounted on the output end of the drive motor 10. A connecting sleeve 11 is fixedly connected to the connecting frame 2, and a second gear 13, matching the size of the first gear 12, is fixedly fitted onto the outer edge of the connecting sleeve 11. The first gear 12 and the second gear 13 mesh with each other. Therefore, when it is necessary to fine-tune the angle of the chip on the pick-up plate 3, the drive motor 10 is started, causing the first gear 12 at the output end of the drive motor 10 to rotate, which in turn causes the second gear 13 and the connecting sleeve 11 to rotate synchronously. This fine-tunes the angle of the chip on the pick-up plate 3 according to the target mounting position of the substrate, compensating for the angular deviation of the chip during positioning and improving the flexibility of the chip mounting process. In this embodiment, the tooth width of the first gear 12 is greater than the tooth width of the second gear 13. When the second gear 13 is displaced in the vertical direction, the first gear 12 and the second gear 13 remain meshed.
[0033] It should be noted that during the stacked chip mounting process, the DAF film of the already mounted chip is in a low temperature state but far from reaching the glass transition temperature. Therefore, the DAF film has a certain structural rigidity, which improves the retention capability of the underlying chip structure when mounting the next layer of chip, making it easier to improve the positioning accuracy and reduce the probability of breakage.
[0034] The implementation principle of this application embodiment is as follows: When chip mounting is required, the robotic arm drives the mounting bracket 1 to move to the position corresponding to the chip on the positioning platform, and starts the vacuum adsorption equipment. The chip is adsorbed onto the pick-up plate 3 through the adsorption channel and adsorption hole 4. The robotic arm drives the chip to move towards the substrate. During the process of the robotic arm driving the chip towards the substrate, the pulse heating ring 5 is energized and instantly generates a high-frequency alternating magnetic field in the space around it. This alternating magnetic field passes through the heat-conducting column 6 located on its inner edge and generates eddy currents. When the eddy currents flow, they encounter resistance, thereby directly converting electrical energy into heat energy, causing the heat-conducting column 6 to heat up rapidly. The heat-conducting column 6 transfers heat to the chip on the pick-up plate 3 and the DAF film, realizing rapid heating of the chip. The robotic arm drives the heated chip to the target mounting position and places the chip on the target mounting position. At the instant the bottom surface of the chip just contacts the substrate, the reaction force generated at the contact point will push the connecting rod 9 to resist the air pressure inside the cylinder 8 and slowly contract it. This process absorbs the downward impact kinetic energy and plays a buffering role, which greatly protects the chip and the substrate. After the connecting rod 9 contracts and buffers the initial impact, the cylinder 8 is activated, and the control system maintains or adjusts the air pressure in the air chamber of the cylinder 8, providing a preset amount of air to the inside of the cylinder 8 to provide a preset pressure to the chip. The vacuum adsorption equipment is turned off to release the adsorption on the chip, and the chip is placed on the target mounting position on the substrate. The robot arm drives the unloaded mounting bracket 1 to move towards the positioning platform to reset. During the repositioning of the mounting bracket 1 from the substrate toward the positioning platform, the circulation unit drives the coolant to flow from the external storage tank and into the cooling channel of the cooling ring 7. The coolant absorbs heat through heat exchange during its flow, thereby reducing the temperature of the connecting bracket 2 and the pick-up plate 3. High-speed cooling is achieved through the control of the coolant's gas-liquid conversion and microfluidic flow. After cooling, the pick-up plate 3 repeats the above steps to perform subsequent chip placement operations on the positioning platform, achieving low-temperature chip pickup. As the robotic arm moves the chip toward the substrate, a heating device is activated to heat the chip on the pick-up device. This preheating of the DAF film and glass transition are completed before the chip reaches the mounting height, significantly reducing chip placement time and improving chip placement efficiency.
[0035] Example 2 Embodiment 2 of this application discloses a chip mounting method based on the above-described chip mounting structure, including: Step 1: The robotic arm moves the mounting frame 1 to the position corresponding to the chip on the positioning platform; Step 2: Start the vacuum adsorption equipment and adsorb the chip onto the material handling plate 3 through the adsorption hole 4; Step 3: The robotic arm moves the chip toward the substrate. During the movement of the chip toward the substrate, the pulse heating ring 5 is energized to generate an alternating magnetic field. The heat-conducting column 6 converts the magnetic energy into heat energy, so that the heat is transferred from the heat-conducting column 6 to the chip on the picking plate 3 and the DAF film. Step 4: The robotic arm moves the heated chip to the target mounting position and places the chip on the target mounting position. It should be noted that if it is necessary to fine-tune the angle of the chip on the pick-up board 3 according to the actual situation on site, the drive motor 10 is started, which drives the first gear 12 at the output end of the drive motor 10 to rotate, which drives the second gear 13 and the connecting sleeve 11 to rotate synchronously, adjusting the chip on the pick-up board 3 to a posture that matches the target mounting position of the substrate, and then placing the chip on the target mounting position. Step 5: At the instant the bottom surface of the chip just touches the substrate, the reaction force generated at the contact point will push the connecting rod 9 to resist the air pressure inside the cylinder 8, causing it to slowly contract and absorb the impact. Step 6: After the connecting rod 9 retracts and buffers the initial impact, start the cylinder 8, control the system to maintain or adjust the air pressure in the air chamber of the cylinder 8, and provide a preset amount of air to the inside of the cylinder 8 to provide a preset amount of pressure to the chip. Step 7: Turn off the vacuum adsorption equipment to release the adsorption of the chip, and place the chip onto the target mounting position on the substrate; Step 8: The robotic arm moves the unloaded mounting frame 1 toward the positioning platform to reset. During the resetting process of the mounting frame 1 from the substrate toward the positioning platform, the circulation unit drives the coolant to flow out from the external storage tank and into the cooling channel of the cooling ring 7. The coolant absorbs heat through heat exchange during the flow process, cooling the connecting frame 2 and the picking plate 3. After cooling, the picking plate 3 repeats the above steps to perform subsequent chip mounting operations on the positioning platform.
[0036] It should be noted that a chip mounting method based on the above chip mounting structure also includes the following steps: when the chip mounting structure is completely shut down, the cylinder 8 is evacuated to drive the connecting rod 9 to extend and retract, and the control system evacuates the cylinder 8 to provide additional tension to the connecting rod 9 on the connecting frame 2.
[0037] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.
Claims
1. A chip mounting structure, characterized in that: A mounting frame (1) is provided on the moving end of the robot arm. A connecting frame (2) is provided on the mounting frame (1). A picking device for picking up chips is provided on the connecting frame (2). A heating device for heating the picking device is provided on the connecting frame (2).
2. The chip mounting structure according to claim 1, characterized in that: The material handling device includes a material handling plate (3) set on the connecting frame (2), the material handling plate (3) is provided with a plurality of adsorption holes (4), and the material handling plate (3) is provided with an adsorption channel communicating with the plurality of adsorption holes (4), the adsorption channel being connected to a vacuum adsorption device.
3. The chip mounting structure according to claim 2, characterized in that: The heating device includes a magnetic field unit for generating an alternating magnetic field and a heat conduction unit for outputting the heat generated by the magnetic field. The magnetic field unit includes a pulse heating ring (5) disposed on the connecting frame (2). The heat conduction unit includes a heat conduction column (6) disposed on the connecting frame (2). The heat conduction column (6) is located on the inner edge of the pulse heating ring (5). The material taking plate (3) is disposed on the heat conduction column (6).
4. The chip mounting structure according to claim 3, characterized in that: The connecting frame (2) is provided with a cooling device for cooling the material taking device. The cooling device includes a cooling ring (7) set on the connecting frame (2). A cooling channel for circulating coolant is opened in the cooling ring (7). The pulse heating ring (5) is located between the cooling ring (7) and the material taking plate (3). The mounting frame (1) is provided with a circulation unit for driving coolant to circulate in the cooling channel.
5. The chip mounting structure according to claim 4, characterized in that: The mounting bracket (1) is provided with a vertically arranged cylinder (8), and the output end of the cylinder (8) is provided with a connecting rod (9). The connecting bracket (2) is located at the end of the connecting rod (9) away from the mounting bracket (1).
6. The chip mounting structure according to claim 1, characterized in that: The connecting frame (2) is rotatably connected to the mounting frame (1). The mounting frame (1) is provided with a drive motor (10). The output end of the drive motor (10) is provided with a first gear (12). The connecting frame (2) is provided with a connecting sleeve (11). The outer edge of the connecting sleeve (11) is fixedly fitted with a second gear (13) that matches the first gear (12). The first gear (12) and the second gear (13) mesh with each other.
7. The chip mounting structure according to claim 6, characterized in that: The tooth width of the first gear (12) is greater than the tooth width of the second gear (13).
8. The chip mounting structure according to claim 6, characterized in that: The connecting frame (2) is provided with a heat insulation plate (14), and the connecting sleeve (11) is provided on the heat insulation plate (14) and the heat insulation plate (14) is located on the side of the heating device away from the material taking device.
9. A chip mounting method based on the chip mounting structure of claim 5, characterized in that, The method includes: The robotic arm moves the mounting bracket (1) to the position corresponding to the chip on the positioning platform, starts the vacuum adsorption equipment, and adsorbs the chip onto the picking plate (3) through the adsorption hole (4). The robotic arm moves the chip toward the substrate. During the process of the chip moving toward the substrate, the pulse heating ring (5) is energized to generate an alternating magnetic field, and the heat-conducting column (6) converts the magnetic energy into heat energy, so that the heat is transferred from the heat-conducting column (6) to the chip on the pick-up plate (3) and the DAF film. The robotic arm moves the heated chip to the target mounting position and places the chip on the target mounting position; Start the cylinder (8) and provide a preset amount of air into the cylinder (8) to provide a preset pressure to the chip; turn off the vacuum adsorption device to release the adsorption of the chip, place the chip onto the target mounting position on the substrate, and the robot arm drives the unloaded mounting bracket (1) to move toward the positioning platform to reset. During the process of the mounting bracket (1) being reset from the base plate toward the positioning platform, the circulation unit is activated to drive the coolant to circulate in the cooling channel to cool the connecting bracket (2) and the material picking plate (3).
10. A chip mounting method based on the chip mounting structure of claim 9, characterized in that, The method further includes: when the chip patch structure is shut down as a whole, the cylinder (8) is evacuated to drive the connecting rod (9) to extend and retract, so that the connecting rod (9) provides tension to the connecting frame (2).