A fixing structure for SMT circuit board

Abstract

The utility model discloses a kind of SMT's circuit board mounting board fixing structure, more specifically related to circuit board processing technical field, including substrate, rectangular frame fixedly connected on the upper end of substrate, rectangular frame one is symmetrically arranged on the upper side of rectangular frame, two sliding frames are slidably arranged in the outer side of each rectangular frame one, rectangular frame two is movably penetrated and connected on each rectangular frame one, clamping plate is fixedly connected on rectangular frame two, drag plate is fixedly connected on clamping plate, support column is fixedly connected in the middle of the upper end of substrate, supporting tray is fixedly connected on the upper end of support column, two smooth rods are fixedly connected in the inner side of rectangular frame, scale plate is slidably connected in the outer side of two smooth rods.The utility model makes multiple sets of jig adapt irregular circuit board by component independent adjustment, positioning mechanism fixed adjustment position prevents displacement, scale plate auxiliary accurate adjustment, solve traditional clamping adaptation difference, prone to misalignment problem, realize the stable clamping to irregular board, satisfy SMT processing demand.

Description

Technical Field

[0001] This utility model relates to the field of circuit board processing technology, and more specifically, to a circuit board mounting and fixing structure for SMT (Surface Mount Technology). Background Technology

[0002] Surface Mount Technology (SMT) is one of the core processes in the electronics manufacturing industry, widely used in the production of various electronic products such as smartphones, computers, IoT devices, and automotive electronics. In the complete SMT process chain (solder paste printing → component placement → reflow soldering → inspection), the circuit board (such as rigid PCB, flexible FPC, rigid-flex PCB) serves as the carrier for electronic components. The stability and accuracy of its mounting directly determine the processing quality of subsequent processes. If the mounting fails, it can lead to solder paste misalignment and component misplacement, or even worse, poor soldering and component damage, ultimately affecting product yield and reliability. Therefore, the mounting structure is a key functional component in SMT production equipment (such as fully automatic solder paste printers, high-speed pick-and-place machines, and reflow ovens), and its performance must be adapted to the material, thickness, size, and production efficiency requirements of the circuit board.

[0003] Existing circuit board fixing mechanisms mostly adopt edge clamping methods, based on the "synchronous symmetrical advancement" design of a single rectangular board. This means that the clamping components on both sides are advanced synchronously by cylinders to clamp the edge of the circuit board. However, this method has low adaptability to circuit boards and cannot be adapted to irregular circuit boards such as double rectangular staggered splicing. Because these boards do not have a uniform rectangular outline, when the clamping components on both sides are advanced synchronously, either one side fails to make contact, causing the board to tilt and shift, or one side is too tight and damages the edge of the board, which in turn leads to placement misalignment and soldering failure. Customizing and modifying clamping components is costly, time-consuming, and lacks shape adaptability, which has become a key bottleneck in the SMT production of such irregular boards.

[0004] In summary, to meet the SMT production needs of irregular circuit boards such as double-rectangular staggered splicing and to improve the adaptability and stability of the fixing mechanism, it is necessary to solve the problems of low adaptability and lack of shape self-adaptation capability of the existing edge clamping mechanism due to the "synchronous symmetrical advancement" design, as well as the high cost and time-consuming customization and modification. This will enable irregular circuit boards to be stably clamped, avoid placement misalignment and soldering failure, and ensure SMT production yield and efficiency. Utility Model Content

[0005] The present invention provides a circuit board mounting and fixing structure for SMT, which aims to solve the problem that existing edge clamping mechanisms have low adaptability and lack of shape self-adaptation capability due to their "synchronous symmetrical advancement" design, and that customization and modification are costly and time-consuming.

[0006] To achieve the above objectives, this utility model provides the following technical solution: an SMT circuit board mounting and fixing structure, comprising a substrate, a rectangular frame fixedly connected to the upper end of the substrate, rectangular frames symmetrically arranged on both sides above the rectangular frame, two sliding frames slidably arranged on the outer side of each rectangular frame, a rectangular frame 2 movably connected through each rectangular frame, a clamping plate fixedly connected to the rectangular frame 2, a sliding plate fixedly connected to the clamping plate, a support column fixedly connected to the middle of the upper end of the substrate, a support tray fixedly connected to the upper end of the support column, two smooth rods fixedly connected to the inner side of the rectangular frame, a scale plate slidably connected to the outer side of the two smooth rods, a distance adjustment mechanism mounted on the rectangular frame, and positioning mechanism 1 and positioning mechanism 2 mounted on the sliding frames. The output end of the distance adjustment mechanism is connected to the two rectangular frames 1, the distance adjustment mechanism is used to adjust the distance between the two rectangular frames 1, the positioning mechanism 1 is used to position and fix the corresponding rectangular frame 2, and the positioning mechanism 2 is used to position and fix the position of the sliding frame on the rectangular frame 1.

[0007] In a preferred embodiment, the distance adjustment mechanism includes a drive component 1 and a guide component mounted on a rectangular frame. The output end of the drive component 1 is connected to two rectangular frames 1, and the drive component 1 is used to drive the two rectangular frames 1 to move closer or further apart relative to each other.

[0008] In a preferred embodiment, the drive assembly includes a bidirectional screw rotatably connected to the inside of a rectangular frame, two movable plates symmetrically threaded to the outside of both ends of the bidirectional screw, and a motor fixedly connected to the outside of the rectangular frame. The output end of the motor is fixedly connected to the bidirectional screw, and the motor is used to drive the bidirectional screw to rotate. The two movable plates are fixedly connected to the two rectangular frames respectively.

[0009] In a preferred embodiment, the guide assembly includes two fixed rods fixedly connected within a rectangular frame and two movable plates symmetrically and movably connected to the outside of each fixed rod, each movable plate being fixedly connected to a corresponding rectangular frame.

[0010] In a preferred embodiment, the positioning mechanism includes a fastening component and a driving component two mounted on the sliding frame. The output end of the driving component two is connected to the input end of the fastening component, and the driving component positions and fixes the rectangular frame two through the fastening component.

[0011] In a preferred embodiment, the fastening assembly includes an N-shaped frame fixedly connected to the sliding frame and an N-shaped pressure plate movably connected to the inside of the N-shaped frame, wherein the opening length of the N-shaped pressure plate is set to be greater than the width of the rectangular frame.

[0012] In a preferred embodiment, the second drive assembly includes a threaded post rotatably connected between the sliding frame and the N-type frame, and a knob rotatably connected to the upper end of the N-type frame. The N-type pressure plate is threaded to the outside of the threaded post, and the knob is fixedly connected to the threaded post via a shaft.

[0013] In a preferred embodiment, the positioning mechanism 2 includes positioning ear plates fixedly connected to both sides of the sliding frame, a plurality of positioning holes 1 that are equally spaced through the rectangular frame 1, positioning holes 2 that are through the positioning ear plates, and pins inserted into the positioning holes 2 and the corresponding positioning holes 1.

[0014] In a preferred embodiment, the zero mark starting line on the scale is located in the middle, and the scale value extends to both sides.

[0015] The beneficial effects of this utility model are as follows:

[0016] This utility model, through the independent adjustment of the sliding frame and the second rectangular frame, first adapts to the edge clamping position of the irregular circuit board and maintains a consistent distance, and then completes unified clamping with the distance adjustment mechanism. It breaks through the limitations of traditional synchronous propulsion, realizes uniform and stable clamping of irregular boards, improves the clamping adaptability of the fixture, and is applicable to a variety of irregular circuit boards, while also avoiding tilting and crushing.

[0017] This utility model, by setting up positioning mechanism one and positioning mechanism two, fixes the position after adjusting rectangular frame two and sliding frame, effectively avoiding subsequent movement, ensuring accurate and stable clamping position, and reducing the risk of misalignment and welding failure.

[0018] This invention uses a scale plate to visually display the distance between the edge of the circuit board and the clamping plate, providing a clear reference for adjustment, greatly improving the adjustment efficiency and accuracy of irregular boards, and adapting to the needs of multiple product replacements. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall three-dimensional structure of this utility model.

[0020] Figure 2 This is a partial three-dimensional structural diagram of the present invention.

[0021] Figure 3 This is a partially enlarged structural diagram of the rectangular frame of this utility model.

[0022] Figure 4 This is a schematic diagram of the sliding frame connection structure of this utility model.

[0023] Figure 5 For the present utility model Figure 4 Partial disassembly diagram.

[0024] The attached figures are labeled as follows: 1. Base plate; 2. Rectangular frame; 3. Rectangular frame one; 4. Sliding frame; 5. Clamping plate; 6. Slide plate; 701. Bidirectional screw; 702. Moving plate one; 703. Motor; 704. Fixing rod; 705. Moving plate two; 801. N-type frame; 802. N-type pressure plate; 803. Threaded post; 804. Knob; 901. Positioning ear plate; 902. Positioning hole one; 903. Positioning hole two; 904. Pin; 10. Rectangular frame two; 11. Support column; 12. Support plate; 13. Smooth rod; 14. Scale plate. Detailed Implementation

[0025] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0026] Refer to the instruction manual appendix Figures 1 to 5 A SMT circuit board mounting and fixing structure includes a substrate 1, a rectangular frame 2 fixedly connected to the upper end of the substrate 1, rectangular frames 3 symmetrically arranged on both sides above the rectangular frame 2, two sliding frames 4 slidably arranged on the outside of each rectangular frame 3, a rectangular frame 2 10 movably connected through each rectangular frame 3, a clamping plate 5 fixedly connected to the rectangular frame 2 10, a sliding plate 6 fixedly connected to the clamping plate 5, a support column 11 fixedly connected to the middle of the upper end of the substrate 1, a support tray 12 fixedly connected to the upper end of the support column 11, two smooth rods 13 fixedly connected to the inner side of the rectangular frame 2, a scale plate 14 slidably connected to the outside of the two smooth rods 13, a distance adjustment mechanism mounted on the rectangular frame 2, and a positioning mechanism 1 and a positioning mechanism 2 mounted on the sliding frames 4. The output end of the distance adjustment mechanism is connected to the two rectangular frames 3. The distance adjustment mechanism is used to adjust the distance between the two rectangular frames 3. The positioning mechanism 1 is used to position and fix the corresponding rectangular frame 2 10. The positioning mechanism 2 is used to position and fix the sliding frame 4 on the rectangular frame 3.

[0027] It should be noted that the overall structure is designed around the four corners of the irregular circuit board. The base plate 1 serves as the basic support for the rectangular frame 2. The support tray 12 is fixed to the middle of the base plate 1 by the support column 11 to support the bottom of the circuit board and prevent the middle from sagging. Four sets of clamps consisting of clamping plates 5 and sliding plates 6 correspond to the four corners of the circuit board. The position is adjusted by the cooperation of rectangular frame 1 3, sliding frame 4 and rectangular frame 2 10. The scale plate 14 slides along the smooth rod 13 to provide a visual reference for the position calibration of the clamps. All mechanisms work together to complete the clamping process from coarse adjustment to fine adjustment and then to fixation.

[0028] Refer to the instruction manual appendix Figure 2The distance adjustment mechanism includes a drive assembly and a guide assembly mounted on a rectangular frame 2. The output end of the drive assembly is connected to two rectangular frames 3. The drive assembly is used to drive the two rectangular frames 3 to move closer or further apart.

[0029] It should be noted that the distance adjustment mechanism consists of a drive component and a guide component. The core is that the drive component provides power to drive the two rectangular frames 3 to move closer or further apart, while the guide component constrains the movement trajectory. The two work together to ensure that the rectangular frames 3 do not deviate or tilt during the adjustment process, laying the foundation for the precise alignment of the subsequent fixtures and solving the problem that traditional synchronous propulsion cannot adapt to irregular plates.

[0030] Refer to the instruction manual appendix Figure 2 The drive assembly includes a bidirectional screw 701 rotatably connected to the inner side of the rectangular frame 2, movable plates 702 symmetrically threaded to the outer sides of both ends of the bidirectional screw 701, and a motor 703 fixedly connected to the outer side of the rectangular frame 2. The output end of the motor 703 is fixedly connected to the bidirectional screw 701, and the motor 703 is used to drive the bidirectional screw 701 to rotate. The two movable plates 702 are fixedly connected to the two rectangular frames 3 respectively.

[0031] It should be noted that after the motor 703 of the drive component 1 starts, it drives the bidirectional screw 701 inside the rectangular frame 2 to rotate. Since the threads at both ends of the bidirectional screw 701 are opposite, the movable plate 702 connected symmetrically on its outer side will move in the opposite direction in sync, thereby driving the two rectangular frames 3 to achieve spacing adjustment. This design can quickly respond to the overall width requirements of different circuit boards, and the power transmission is direct and stable.

[0032] Another alternative embodiment based on the design of drive component one replaces the original combination of "motor 703 + bidirectional screw 701" in drive component one with a completely new structure of "dual-axis cylinder + displacement sensor + pressure regulating valve". In this embodiment, the piston rod of the dual-axis cylinder is rigidly connected directly to the moving plate 702, allowing independent control of the movement stroke of the two rectangular frames 3. The displacement sensor, installed at the end of the piston rod, can capture real-time position changes of the moving plate 702. If the actual displacement deviates from the target value, it can automatically trigger cylinder adjustment to ensure adjustment accuracy. The pressure regulating valve assists in stabilizing the cylinder output. By increasing the output force and avoiding damage to the circuit board due to force fluctuations during clamping, this optimized structure, compared to the original solution, solves the problems of slow start-up response, limited small-stroke adjustment accuracy, and inability to adjust independently on one side of the original "motor 703 + bidirectional screw 701" design. Not only is the start-up response speed significantly improved, but the extension amount of the cylinder on one side can also be individually set according to the different width requirements of the two sides of irregular circuit boards, such as double-rectangular staggered splicing boards, without relying on the symmetrical motion logic of the screw, significantly enhancing adaptability and flexibility. At the same time, it avoids the risk of motor 703 stalling during operation, reduces mechanical failures, and extends the service life of the overall structure.

[0033] Refer to the instruction manual appendix Figure 2 The guide assembly includes two fixed rods 704 fixedly connected within the rectangular frame 2 and two movable plates 705 symmetrically and movably connected to the outside of each fixed rod 704. Each movable plate 705 is fixedly connected to the corresponding rectangular frame 3.

[0034] It should be noted that the two fixed rods 704 of the guide assembly are fixed in parallel inside the rectangular frame 2. Two movable plates 705 are symmetrically sleeved on the outside of each fixed rod 704. The movable plates 705 are fixedly connected to the rectangular frame 3. When the rectangular frame 3 moves, the movable plates 705 slide along the fixed rods 704 to counteract the torque generated by the rotation of the bidirectional screw 701, prevent the rectangular frame 3 from twisting, and ensure that the fixture always maintains a horizontal posture.

[0035] Refer to the instruction manual appendix Figure 3 and Figure 4 The positioning mechanism includes a fastening component and a driving component 2 mounted on the sliding frame 4. The output end of the driving component 2 is connected to the input end of the fastening component. The driving component positions and fixes the rectangular frame 2 10 through the fastening component.

[0036] It should be noted that the positioning mechanism 1 drives the fastening component through the driving component 2 to achieve the positioning and fixing of the rectangular frame 2 10. During adjustment, the driving component 2 outputs power to the fastening component, and the fastening component switches from the loose state to the locked state to lock the position of the rectangular frame 2 10, ensuring that the distance between the clamping plate 5 and the edge of the circuit board is stable. This is a key step in accurately adapting to the edge of the irregular board.

[0037] Refer to the instruction manual appendix Figure 3 and Figure 4 The fastening assembly includes an N-type frame 801 fixedly connected to the sliding frame 4 and an N-type pressure plate 802 movably connected to the inside of the N-type frame 801. The opening length of the N-type pressure plate 802 is set to be greater than the width of the rectangular frame 3.

[0038] It should be noted that the N-type bracket 801 of the fastening component is fixed on the sliding bracket 4. The opening length of the N-type pressure plate 802 connected on the inner side is greater than the width of the rectangular bracket 3, so that it can be placed across the outside of the rectangular bracket 3 and can act precisely on the rectangular bracket 10. When the N-type pressure plate 802 is pressed, the friction can be enhanced by increasing the contact area, thus preventing the rectangular bracket 10 from loosening.

[0039] Refer to the instruction manual appendix Figure 3 and Figure 4The second drive assembly includes a threaded post 803 rotatably connected between the sliding frame 4 and the N-type frame 801, and a knob 804 rotatably connected to the upper end of the N-type frame 801. The N-type pressure plate 802 is threadedly connected to the outside of the threaded post 803, and the knob 804 is fixedly connected to the threaded post 803 via a shaft.

[0040] It should be noted that the threaded post 803 of the drive assembly 2 is rotatably connected between the sliding frame 4 and the N-type frame 801. The top end is connected to the knob 804 via a shaft. The N-type pressure plate 802 is threaded on the outside of the threaded post 803. When the knob 804 is rotated, the threaded post 803 drives the N-type pressure plate 802 to move up and down. When it moves up, it loosens the rectangular frame 2 10 for adjustment. When it moves down, it presses to fix it. The operation is convenient and the adjustment accuracy is high.

[0041] Refer to the instruction manual appendix Figures 3 to 5 The second positioning mechanism includes positioning ear plates 901 fixedly connected to both sides of the sliding frame 4, multiple positioning holes 902 equally spaced through the rectangular frame 3, positioning holes 903 through the positioning ear plates 901, and pins 904 inserted into the positioning holes 903 and the corresponding positioning holes 902.

[0042] It should be noted that after the sliding bracket 4 slides along the rectangular bracket 3 to the target position, it aligns the positioning hole 903 with the corresponding positioning hole 902, and inserts the pin 904 to lock the position. Multiple sets of positioning holes can adapt to the corner clamping requirements of circuit boards of different lengths.

[0043] Another alternative embodiment based on the second positioning mechanism design replaces the original combination of "pin 904 + positioning hole 1 902 + positioning hole 2 903" in the second positioning mechanism with an automatic positioning structure of "electromagnet + Hall effect positioning plate + magnetic controller". Specifically, the electromagnet is fixed inside the positioning ear plate 901 of the sliding frame 4, the Hall effect positioning plates are arranged at equal intervals along the side wall of the rectangular frame 3, and the magnetic controller is integrated on the sliding frame 4 and is linked to the signal of the Hall effect positioning plates. During operation, after the sliding frame 4 slides along the rectangular frame 3 to the target position, the Hall effect positioning plates automatically identify the position and send a signal to the magnetic controller, which then drives the electromagnet to generate power. The adsorption force firmly locks the sliding frame 4 onto the rectangular frame 3. When readjustment is needed, the controller only needs to be powered off and demagnetized, and the sliding frame 4 can slide directly without manually inserting or removing the pin 904. This optimized solution completely solves the problems of the original "pin 904 + positioning hole 1 902 + positioning hole 2 903" which required manual alignment of the holes, cumbersome insertion and removal operations, low changeover efficiency, and easy loss and wear of the pin 904. It not only eliminates manual operation steps and greatly shortens the time for single positioning, but also significantly improves changeover efficiency. Furthermore, because the Hall positioning plate has no mechanical contact wear and the electromagnet adsorption is stable, it extends the service life of the components and is more suitable for the high-frequency changeover requirements of SMT production lines.

[0044] Refer to the instruction manual appendix Figure 1 and Figure 2 The zero mark starting line on the scale plate 14 is set in the middle position, and the scale value continues to expand to both sides.

[0045] It should be noted that this design allows operators to intuitively read the distance from the two edges of the circuit board to the corresponding clamping plate 5. For irregular boards such as double rectangular staggered splicing, the difference in scale on both sides can be compared to quickly determine whether the clamp adjustment matches the shape of the board, greatly improving positioning efficiency and accuracy.

[0046] Working principle:

[0047] 1. Placement of substrate 1: Place the irregular circuit board on the support tray 12 in the middle of substrate 1, and support it with the support column 11 to prevent it from sagging.

[0048] 2. Coarse adjustment and locking of sliding frame 4: Push sliding frame 4 along rectangular frame 3 according to the length of the circuit board, align the positioning ear plate 901 with the hole of rectangular frame 3, insert pin 904 to lock through positioning mechanism 2, and initially determine the position of the fixture.

[0049] III. Calibration reference of scale plate 14: Push the scale plate 14 to slide along the smooth rod 13, corresponding to the edge of the circuit board and the position of the clamp, and use the scale to intuitively judge the difference in distance from the edge of the board to the clamp plate 5.

[0050] IV. Fine-tuning and fixing of rectangular frame 2 10: Turn knob 804 to loosen N-type pressure plate 802, pull rectangular frame 2 10 to adjust the distance between clamp 5 and the edge of the plate, and after ensuring that the distance is consistent with the scale, tighten the pressure plate in the opposite direction and lock it through positioning mechanism 1.

[0051] V. Drive clamping to complete fixation: Start motor 703 drives bidirectional screw 701 to rotate, so that moving plate 702 drives rectangular frame 3 (with fixed rod 704 for guidance) to move closer to each other. The four sets of clamps simultaneously clamp the four corners of the circuit board to complete fixation.

[0052] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model.

Claims

1. A circuit board mounting and fixing structure for SMT (Surface Mount Technology), characterized in that: Includes a substrate (1), a rectangular frame (2) fixedly connected to the upper end of the substrate (1), rectangular frames (3) symmetrically arranged on both sides above the rectangular frame (2), two sliding frames (4) slidably arranged on the outside of each rectangular frame (3), a rectangular frame (10) movably connected through each rectangular frame (3), a clamping plate (5) fixedly connected to the rectangular frame (10), a sliding plate (6) fixedly connected to the clamping plate (5), a support column (11) fixedly connected to the middle of the upper end of the substrate (1), a support tray (12) fixedly connected to the upper end of the support column (11), and fixed connections. The rectangular frame (2) has two smooth rods (13) inside, a scale plate (14) slidably connected to the outside of the two smooth rods (13), a distance adjustment mechanism installed on the rectangular frame (2), and positioning mechanism one and positioning mechanism two installed on the sliding frame (4). The output end of the distance adjustment mechanism is connected to the two rectangular frames (3). The distance adjustment mechanism is used to adjust the distance between the two rectangular frames (3). Positioning mechanism one is used to position and fix the corresponding rectangular frame (2) (10). Positioning mechanism two is used to position and fix the sliding frame (4) on the rectangular frame (3).

2. The SMT circuit board mounting and fixing structure according to claim 1, characterized in that: The distance adjustment mechanism includes a drive assembly and a guide assembly mounted on a rectangular frame (2). The output end of the drive assembly is connected to two rectangular frames (3). The drive assembly is used to drive the two rectangular frames (3) to move closer or further apart.

3. The SMT circuit board mounting and fixing structure according to claim 2, characterized in that: The drive assembly includes a bidirectional screw (701) rotatably connected to the inside of the rectangular frame (2), a movable plate (702) symmetrically threaded to the outside of both ends of the bidirectional screw (701), and a motor (703) fixedly connected to the outside of the rectangular frame (2). The output end of the motor (703) is fixedly connected to the bidirectional screw (701), and the motor (703) is used to drive the bidirectional screw (701) to rotate. The two movable plates (702) are fixedly connected to the two rectangular frames (3) respectively.

4. The SMT circuit board mounting and fixing structure according to claim 2, characterized in that: The guide assembly includes two fixed rods (704) fixedly connected inside the rectangular frame (2) and two movable plates (705) symmetrically connected to the outside of each fixed rod (704), each movable plate (705) being fixedly connected to the corresponding rectangular frame (3).

5. The SMT circuit board mounting and fixing structure according to claim 1, characterized in that: The positioning mechanism includes a fastening component and a driving component 2 mounted on the sliding frame (4). The output end of the driving component 2 is connected to the input end of the fastening component. The driving component positions and fixes the rectangular frame 2 (10) through the fastening component.

6. The SMT circuit board mounting and fixing structure according to claim 5, characterized in that: The fastening assembly includes an N-type frame (801) fixedly connected to the sliding frame (4) and an N-type pressure plate (802) movably connected to the inside of the N-type frame (801). The opening length of the N-type pressure plate (802) is set to be greater than the width of the rectangular frame (3).

7. The SMT circuit board mounting and fixing structure according to claim 6, characterized in that: The second drive assembly includes a threaded post (803) rotatably connected between the sliding frame (4) and the N-type frame (801) and a knob (804) rotatably connected to the upper end of the N-type frame (801). The N-type pressure plate (802) is threadedly connected to the outside of the threaded post (803), and the knob (804) is fixedly connected to the threaded post (803) via a shaft.

8. The SMT circuit board mounting and fixing structure according to claim 1, characterized in that: The second positioning mechanism includes positioning ear plates (901) fixedly connected to both sides of the sliding frame (4), multiple positioning holes (902) that are equally spaced through the rectangular frame (3), positioning holes (903) that are through the positioning ear plates (901), and pins (904) inserted into the positioning holes (903) and the corresponding positioning holes (902).

9. The SMT circuit board mounting and fixing structure according to claim 1, characterized in that: The zero mark starting line on the scale plate (14) is set in the middle position, and the scale value continues to expand to both sides.

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