227 results about "Surface-mount technology" patented technology

The invention relates to the technical field of surface mounting control, and discloses an SMT surface mounting optimization control method and system based on multi-source data, and the method comprises the steps: collecting current surface mounting information, comparing the current surface mounting information with optimization judgment parameters, and judging whether to carry out surface mounting optimization control or not. When it is judged that optimization is carried out, historical SMT patch image data are collected, and defect feature vectors are obtained; and constructing an electrical attribute vector and a three-dimensional space distribution model of the soldering paste, executing thermal simulation calculation, and obtaining a thermal field distribution diagram of the component mounting area. And taking the defect feature vector, the electrical attribute vector and the thermal field distribution diagram as multi-source input, inputting the multi-source input into a multi-head attention neural network model, and outputting a patch optimization control parameter group. And driving the surface mounting equipment to execute surface mounting operation according to the surface mounting information and the surface mounting optimization control parameter group. According to the invention, the mounting reliability, customization capability and self-adaptability are improved, and precise and high-quality mounting control of complex special-shaped devices and high-temperature-sensitive elements can be realized.

The invention relates to the technical field of electronic manufacturing, in particular to a PCB SMT mounting method and system based on optical recognition, and the method comprises the steps: carrying out the datum point collection of a pre-confirmed circuit board, obtaining an actual datum point image, carrying out the deviation calculation through employing a theoretical datum point image and the actual datum point image, obtaining an offset, obtaining a plurality of qualified mounting elements, and carrying out the recognition of the qualified mounting elements. The method comprises the following steps: carrying out offset analysis on qualified surface-mounted components to obtain a component center coordinate offset value, carrying out movement compensation on surface-mounted coordinates by utilizing the offset and the component center coordinate offset value to obtain target surface-mounted coordinates, and carrying out surface-mounted on a plurality of qualified surface-mounted components corresponding to a plurality of target surface-mounted coordinates based on the plurality of target surface-mounted coordinates. And carrying out continuous tin defect detection on the surface-mounted circuit board, and taking the surface-mounted circuit board of which the defect score is greater than a defect score threshold as a finished product circuit board. According to the invention, the problems of positioning deviation and tin connection welding quality defects during circuit board mounting can be solved.

The invention relates to the technical field of surface mounting, and discloses an SMT (Surface Mount Technology)-based patch vision correction method, which comprises the following steps: S1, a calibration stage: constructing a double-coordinate system mapping model based on a PCB (Printed Circuit Board) plane, and establishing a nonlinear distortion compensation matrix according to the patch thickness; s2, a pickup stage: a CCD shooting camera is arranged at the top of the suction nozzle, a top CCD is triggered to shoot when the suction nozzle picks up an element, and pin coplanarity data is extracted; s3, a positioning stage: setting a reference point at the top of the PCB, scanning the PCB reference point through a CCD, and calculating a deviation between an actual position and a theoretical coordinate by using an algorithm processor; and S4, compensation execution: the motion shaft system dynamically adjusts the mounting path according to the deviation vector. The visual correction method based on SMT pasting has the advantages of accurate pasting and the like, and solves the problems of pasting position offset, low efficiency and unstable precision caused by factors such as vibration of an element feeder, mechanical transmission errors and thermal deformation of a PCB (Printed Circuit Board) due to dependence on manual calibration in the existing SMT pasting process.

The disclosed front end architectures are configured to conglomerate duplexer transmission (TX) contours into a specific or targeted region. This enables the power amplifier (PA) to match a larger number of frequency bands without the help of additional matching networks. The disclosed architectures are advantageous because they reduce the number of components (e.g., surface mount technology components (SMTs)) required for radio-frequency (RF) modules, such as front end modules, power amplifier modules, and the like. The disclosed architectures are also advantageous because they improve performance of the modules across a wider range of frequency bands.

A surface mountable optoelectronic device with side walls including slots filled with a laminated encapsulant material is presented herein. A surface mount technology (SMT) optoelectronic device includes a substrate, a housing, at least one optoelectronic chip, and an encapsulant material. The substrate includes electrical terminals that facilitate attachment and electrical coupling of the SMT optoelectronic device to a printed circuit board. The housing includes an opaque material and a cavity, in which the substrate is positioned at a bottom portion of the cavity, and a top portion of the housing includes a group of slot openings. The at least one optoelectronic chip is electrically connected to the electrical terminals, and is mounted, within the cavity, to the substrate. The encapsulant material is translucent or transparent, and has been included in the cavity and the slot openings.

The invention discloses a field calibration method and system for SMT 3D AOI equipment, and relates to the surface mounting technology, and the method comprises the steps: feeding a calibration board into the SMT 3D AOI equipment according to the same board feeding mode as a common PCB, and carrying out the initialization; multiple groups of horizontal and vertical grating images are acquired; performing phase calculation on the grating image acquired by the camera by using a phase shift method to obtain a plurality of groups of horizontal and vertical phase diagrams; performing image processing on the calibration plate image acquired by the camera, calculating circle center coordinates of all the circular patterns, and calculating corresponding point coordinates of the circle center coordinates on the imaging plane of each projector; calculating coordinate values of all circle centers on the calibration plate in a world coordinate system according to the adopted Z-axis height and the distance between the circular patterns of the calibration plate; repeatedly calculating world coordinates; and determining optimized system parameters according to the projection process of conversion from the coordinate values of the world coordinate system to the camera pixel coordinate system. According to the invention, the internal parameters and the external parameters of the equipment can be quickly optimized, and the precision of the imaging system is recovered to the initial state.

The utility model discloses a suction nozzle for automatic lossless surface mounting of light-emitting diode materials with lenses for SMT (Surface Mount Technology), which is characterized in that a first clamping groove and a second clamping groove are respectively arranged on the upper surface of a connecting disc from left to right, a reflector is arranged on the lower surface of the connecting disc, a suction nozzle head is arranged on the lower surface of the reflector, and a lens is arranged on the suction nozzle head. The upper end of the suction nozzle head is further integrally connected with a connector, a second cavity and an air suction port are formed in the suction nozzle head from top to bottom, a first cavity communicated with the second cavity is formed in the mounting rod, and a sealing protection pad is further arranged at the lower end of the suction nozzle head. The utility model relates to the technical field of SMT surface mounting. According to the suction nozzle for automatic lossless surface mounting of the light emitting diode material with the lens for SMT, the suction nozzle head can effectively avoid important and sensitive working areas on the upper surface of the diode material, so that protection is achieved, and the purpose of efficient sealing and lossless adsorption of the light emitting diode can be achieved through the sealing protection pad.

The invention relates to the technical field of flip chips, and provides a semiconductor level flip chip surface mounting technology production process, which comprises the following steps: obtaining a circuit board and a flip chip; first solder paste is printed on the circuit board, and the flip chip is pasted to the first solder paste of the circuit board; welding the flip chip to the circuit board through a reflow soldering process; filling the bottom of the flip chip; according to the semiconductor-level flip chip surface mounting technology production process provided by the embodiment of the invention, the flip chip is welded to the circuit board, so that the flip chip has higher connection density and better electrical performance, and the bottom of the flip chip is filled, so that the filler can enhance the mechanical bonding force between the flip chip and the circuit board, thereby improving the reliability of the flip chip. The probability that the flip chip falls off from the circuit board or the welding point is loosened due to external force or temperature change can be effectively reduced.

The utility model provides an LED device based on mini LED lamp drive integrated design, which is characterized in that a drive chip and LED chips are arranged on the front surface of a substrate, extraction electrodes are arranged on the back surface of the substrate, and the LED chips comprise mini LED chips; the leading-out electrodes comprise a red light power supply electrode, a blue-green light power supply electrode, a grounding electrode and three communication electrodes, three positive electrodes of the mini LED chip are respectively connected to the driving chip and are respectively and correspondingly connected to the red light power supply electrode and the blue-green light power supply electrode through the driving chip and the conducting holes so as to respectively drive the red light power supply electrode and the blue-green light power supply electrode, and the driving chip is provided with three communication ports. According to the LED device based on the mini LED lamp drive integrated design, the drive chip and the LED chip are both arranged on the front face of the substrate, only one-time surface mounting technology needs to be executed to the production of a backlight plate, and the production cost of downstream manufacturers can be effectively reduced; the red lamp is driven separately, communication channels are multiple, the controllability of the mini LED chip can be improved, and convenience is provided for power consumption regulation and control and light emitting effect regulation and control.

This application relates to an SMT (Surface Mount Technology) material delivery scheduling method and system. It includes: executing a material delivery task; when reading the identification code of a material tray fails, identifying the failure type as optical overexposure, and reporting the failure information to a central scheduling system; the central scheduling system updates the execution history information of the material delivery task based on the failure information; when the central scheduling system needs to allocate an automated guided vehicle (AGV) to the material delivery task, it queries the execution history information of the material delivery task; if the query results indicate that the material delivery task has failed, it identifies the type of AGV that caused the failure in the execution history information, excludes the AGV type that caused the failure from the available AGVs, and selects AGVs with different physical configurations for allocation. This solves the problem of code reading failure caused by optical overexposure of high-gloss material trays in the SMT production environment.

The utility model discloses a cover plate, a braid type feeding assembly adopting the cover plate and an SMT assembly system. The cover plate comprises a cover plate seat body and a hollow containing cavity which is formed in the cover plate seat body and penetrates through the top end and the lower end of the cover plate seat body. Connecting parts which are turned outwards are arranged on the outer side walls of at least one pair of cover plate seat bodies and located on the edges of the bottom ends of the cover plate seat bodies; and an annular positioning part suitable for being adsorbed is arranged at the top end of the cover plate seat body and is positioned on the circumferential side of the hollow accommodating cavity.

Embodiments of the present application provide a method and apparatus for generating optimized parameters. The method is suitable for generating optimized parameters related to solder paste printing in surface mount technology. In the method, a cluster parameter model is used to determine whether at least one input parameter deviates from at least one parameter cluster. A global parameter model is used to determine the printing result of a plurality of target parameters in the input parameter. A heuristic algorithm is used to select at least one candidate parameter from the target parameters. An individual parameter model is used to modify the candidate parameter. As a result, the optimized parameters with high operation cycle and low failure rate can be obtained.

The utility model relates to interphone SMT paster technical field, in particular to an SMT paster dispenser, including bottom plate, two support frame, transmission subassembly and dispensing mechanism, the two support frame with bottom plate fixed connection, transmission subassembly includes drive motor, drive roller, rolling roller, conveyer belt, limit piece and fixed piece, drive motor with drive roller one end fixed connection, and drive roller one end fixed connection, rolling roller one end fixed connection, conveyer belt one end fixed connection. The other end of the driving roller is rotationally connected with the supporting frame, the rolling roller is rotationally connected with the supporting frame, the conveying belt is arranged on the outer side of the driving roller and the outer side of the rolling roller, the limiting piece is fixedly connected with the supporting frame, the fixing piece is fixedly connected with the supporting frame, and the dispensing mechanism is fixedly connected with the bottom plate. The surface of the circuit board is effectively prevented from moving, so that the reject ratio of the circuit board and the labor intensity of operators are reduced.

The utility model relates to the technical field of surface mounting, in particular to an SMT (Surface Mount Technology) material receiving device with an accurate cutting function, which comprises a bottom plate, the upper end surface of the bottom plate is fixedly connected with a first material placing platform, and the upper end surface of the bottom plate is slidably connected with a second material placing platform; the precise cutting assembly comprises a linear guide rail fixedly connected to the upper end face of the bottom plate, a sliding seat is slidably connected to the linear guide rail, a cutter is fixedly installed on the sliding seat and located between the first discharging platform and the second discharging platform, and a cutting driving part is fixedly installed on the upper end face of the bottom plate. According to the material cutting device, materials can be accurately cut, the cutting consistency of the materials and the tidy degree of connectors can be kept, the phenomenon of equipment alarm caused by insufficient material receiving is reduced, material mounting deviation caused by deviation of the material connectors is reduced, the materials can be fully fixed, and accurate cutting operation of the materials is facilitated.

This invention discloses a compact UAV flight control board core component layout and efficient connection method, belonging to the field of UAV flight control design technology. The layout scheme centers on the main control module, achieving a radial and compact arrangement of various functional modules on a flight control board body with an area not exceeding 50cm²: sensor modules surround the main control module with a spacing not exceeding 5mm, power management and communication modules are diagonally distributed at the edges, and interface expansion modules are dispersed in the remaining edge areas. Independent digital and analog ground copper foils are provided, using single-point grounding. The connection method utilizes surface mount technology for direct soldering of core chips. The power link employs a tree topology and array filtering, while the signal link optimizes impedance matching and wiring. Connection detection and thermal adhesive reinforcement ensure reliability. This invention significantly reduces the size and weight of the flight control board, effectively reduces signal interference and transmission loss, improves connection stability and flight control accuracy, and is suitable for the needs of miniaturized UAVs.

The utility model discloses a cooling frame of an SMT (Surface Mount Technology) jig. The cooling frame comprises a cooling frame main body, a supporting plate and a bottom plate, according to the SMT patch heat dissipation device, the mounting groove, the ventilation opening and the fixing sleeve are arranged, the connecting sleeve is movably mounted through the mounting groove, the fixing groove is formed through the connecting sleeve, the filter plate is mounted through the fixing groove, and the filter plate filters air blown to SMT patch heat dissipation at the heat dissipation fan; according to the utility model, the fixing sleeve is arranged on the cooling frame, and the fixing sleeve is installed through the connecting plate, so that the problems that the cooling frame is not provided with a filtering structure at the cooling fan used for SMT mounting, the cooling fan without the filtering structure may suck dust, impurities and other small particles in the air in the operation process, and the particles can be blown to an SMT mounting area subsequently, so that the service life of the cooling frame is prolonged, and the service life of the cooling frame is prolonged are solved. Due to the fact that the working precision of the SMT chip mounter is extremely high, installation of electronic elements can be affected even if extremely small dust exists, and the problems of poor welding, short circuit or element damage are caused.

The utility model relates to the technical field of SMT (Surface Mount Technology) mounting, and discloses a modular SMT mounting jig convenient to replace, which comprises a base and further comprises supporting plates which are symmetrically arranged above the base, moving plates are arranged on opposite sides of the two supporting plates, rotating rods are rotatably connected to opposite sides of the two moving plates, and the rotating rods are connected with the moving plates. And the other ends of the two rotating rods are fixedly connected with fixing plates. According to the utility model, the distance between the two fixing assemblies can be effectively adjusted through the adjusting assembly, so that patch bodies of different specifications can be effectively fixed, the patch bodies can be effectively fixed through the fixing assemblies, and the patch bodies can be overturned through the overturning assembly. By means of the technical scheme, the patch body can be conveniently turned over, workers do not need to manually turn over the patch body and then fix the patch body again, the processing efficiency of the patch body is effectively improved, and the workload of the workers is relieved.

This invention discloses a staged quality inspection method and system for SMT (Surface Mount Technology) semi-finished products, specifically relating to the field of electronic manufacturing quality management technology. The method includes the following steps: quality inspection is performed at each stage of the production line, the inspection results are recorded and a result set is formed, and early signs of production rhythm imbalance are identified using time interval distribution analysis; if imbalance is present, the defect frequency fluctuation index and the production line dynamic disorder index are further calculated to quantify the dynamic fluctuations and systemic problems of non-conforming phenomena; the two indices are input into a pre-trained machine learning model, and the model output distinguishes the quality status of the production line as high quality or low quality; for low-quality production lines, optimization is performed according to a preset adjustment strategy; this method can monitor the quality status of the production line in real time, accurately distinguish between accidental and non-accidental problems, improve quality management efficiency, ensure stable operation of the production line, and reduce the proportion of non-conforming products.

The utility model provides a magnetic core winding antenna structure suitable for SMT (Surface Mount Technology) assembly, which reduces the volume of an antenna module, enables the antenna module to be mounted in an SMT mode, and enables the connection of the antenna module to be rapid and efficient. The plastic seat comprises a mounting cavity and a welding support plate, and the non-welding surface of the welding support plate is provided with a raised mounting cavity; a magnetic core including a winding shaft; a winding coil; a red copper sheet assembly; and a mylar film; the winding coil is wound around the winding shaft, the two ends of the winding coil are arranged in an outward protruding mode to form connecting parts, the bottom of the magnetic core and the bottom of the winding coil are arranged in an installation cavity of the plastic base, and a red copper sheet assembly is arranged in a supporting plate at the bottom of the plastic base in advance. The connecting parts of the red copper sheet and the winding coil are combined to form corresponding welding spots exposed out of the bottom of the welding support plate; the inner surfaces of the two ends of the mylar in the length direction are connected with the upper surface of the integral structure formed by the magnetic core and the winding coil in an attached mode.

The utility model provides a multi-track feeding device for SMT (Surface Mount Technology), and relates to the technical field of SMT feeding. The multi-track feeding device for SMT comprises a base, a plurality of grooves are formed in the middle of the base, stabilizing frames are fixed to the two sides of the base, a loading frame is slidably connected to the outer surfaces of the two stabilizing frames, a plurality of track grooves are formed in the middle of the loading frame, a driving motor is fixed to one side of the base, and a fixing rod is fixed to the driving end of the driving motor. Cams are fixed in the middles of the fixing rods; limiting grooves are formed in the two sides of the loading frame, a connecting structure is arranged at the other end of the fixing rod, and a threaded frame and a sliding frame are arranged on the connecting structure. According to the multi-track feeding device for SMT, the driving motor drives the fixing rod to rotate, the effect of stable loading is achieved, the effect of improving the using effect of the multi-track feeding device is achieved, the effects of equivalent discharging and arrayed feeding are achieved, and the effect of reducing the manufacturing cost and the using cost is achieved.

The utility model relates to the technical field of surface mounting, in particular to a soldering paste printing device for mainboard production, which comprises a support frame, a first electric slide rail is mounted at the upper part of the support frame, a movable frame is mounted on the first electric slide rail in a sliding manner, an air cylinder is fixedly mounted on the movable frame, and a scraper is assembled at the tail end of a movable rod of the air cylinder. By means of the pressing mechanism composed of the push plate, the wedge-shaped block and the pressing plate, it is guaranteed that the main board is tightly attached to the bottom face of the screen template in the printing process, displacement or warping is avoided, printing consistency and accuracy are guaranteed, meanwhile, uniform and accurate smearing of soldering paste is facilitated, printing quality is improved, and the risks of poor printing and through printing are reduced; according to the device, intelligent control devices such as the electric sliding rail and the air cylinder are integrated, full-automatic operation of soldering paste printing is achieved, the printing speed is increased, manual intervention is reduced, the operation difficulty is lowered, and the device is particularly suitable for the large-scale and high-efficiency production environment.

This invention discloses an adaptive optimization method for SMT production line process parameters based on digital twins, belonging to the field of surface mount technology (SMT) data control technology. It includes constructing a digital twin to map SMT production line elements, reconstructing a model to calculate the SMT production line process status, deriving an SMT production line capacity optimization scheme, dynamically correcting process parameters, eliminating model overfitting faults caused by batch variations in incoming materials, and optimizing the joint simulation of equipment status and process parameters. This invention upgrades SMT production line process optimization from traditional reactive optimization to predictive optimization, reducing quality defects at the source and achieving a fundamental upgrade in the optimization model. Through a four-dimensional hierarchical digital twin and reduced-order model virtual sensing technology, it achieves real-time acquisition of key physical quantities that traditional methods cannot measure, such as thermal field distribution, stencil deformation, and dynamic gaps. This eliminates decision-making blind spots in process optimization, improves the accuracy and timeliness of optimization decisions, and thus fills the data dimension gap in process optimization.

The invention provides an electronic device and a circuit board, and relates to the technical field of electronic equipment. According to the electronic device, the situation that the electronic component shifts and inclines relative to the bonding pad when the electronic component is welded through the surface mounting technology can be reduced. The electronic device comprises a circuit board, an electronic component and a welding layer. Wherein the circuit board is provided with a bonding pad; the connecting end of the electronic component is matched with the bonding pad, at least two accommodating spaces are arranged on one side, facing the electronic component, of the bonding pad and / or one side, facing the bonding pad, of the connecting end in the connecting direction of the connecting end and the bonding pad, and the at least two accommodating spaces are arranged at intervals in the circumferential direction of the bonding pad; and the welding layer is positioned between the connecting end and the bonding pad, is filled in the accommodating space, and is used for fixing and electrically connecting the connecting end and the bonding pad.

The utility model discloses a PCB (Printed Circuit Board) chip mounting device matched with an SMT (Surface Mount Technology) chip mounter for use, which relates to the field of PCB chip mounting processing and comprises a bottom plate arranged on the SMT chip mounter; the bearing box is installed on the bottom plate, the top end of the bearing box is arranged in an opening shape, and a concave table used for supporting the PCB is arranged on the side wall of the top end of the bearing box; the ejector pins are arranged in the bearing box and used for conducting auxiliary supporting on the PCB, and moving driving pieces are arranged at the bottoms of the ejector pins; according to the PCB chip mounting device matched with the SMT chip mounter for use, the bearing box and the detachable ejector pin are arranged, so that PCBs of different versions and different models can be effectively supported, various jigs do not need to be used, the manufacturing cost of an enterprise is reduced, turnover and double-sided chip mounting of the PCBs can be realized on the same station through the integrated turnover mechanism, and the production efficiency is improved. The problem that an additional turn-over step is needed in a traditional process is avoided, and the production process is greatly simplified.

A surface mount technology (SMT) panel frame is provided. The SMT panel frame (100) includes a panel (110) and at least one copper material region (130) disposed on the panel (110). The panel (110) is substantially sufficient to securely hold at least one printed circuit board (120), the panel (110) is removably arranged around the printed circuit board (120), and predetermined areas on the printed circuit board (PCB) (120) are designated for placing data matrix codes (DMC), reference points and test points. At least one copper material region (130) is selectively arranged within the panel (110) based on the arrangement of the data matrix code, the reference and the test points such that the copper material region is aligned with the location and arrangement of the panel reference points, DMC and test points, thereby reducing the need of the entire panel (110) for copper.

The invention discloses an SPI and AOI detection online re-judgment method and system, relates to the technical field of electronic manufacturing surface mounting, and discloses the SPI and AOI detection online re-judgment method and system which realize intelligent correlation analysis of solder paste printing defects by performing coordinate alignment and image superposition processing on SPI height data and AOI optical data. The accuracy and the efficiency of re-judging the printing defects of the soldering paste can be improved.

The invention relates to the technical field of computer vision and deep learning, in particular to an RGB-D salient target detection method based on potential perception and hierarchical fusion. Respectively extracting RGB (Red, Green, Blue) and depth features by taking SMT (Surface Mount Technology) and MobileNetV2 as backbone networks; a potential label is generated by using the depth map and the true value map, and a quality factor output by a depth quality estimation module is supervised; inputting the RGB and depth features into a potential perception interaction module; the multi-scale fusion module and the position sensing fusion module are used for differentially fusing different levels of multi-modal features and mining modal complementarity; a differential decoding strategy is adopted for fusion features of a shallow layer and a deep layer through a layered refining decoder, and semantic guidance and feature refinement are combined; and finally, fusing the edge information into a final saliency map. According to the method, the relevance and complementarity among multi-level and multi-modal features are fully mined, the influence of low-quality features is dynamically inhibited, and the accuracy and robustness of salient target detection are improved.

This invention belongs to the field of semiconductor packaging and surface mount technology, and specifically relates to a method for mounting surface-mount LEDs based on machine vision. The method includes: acquiring 3D point cloud data of the SMD LED using a 3D vision acquisition module, calculating the component's bottom surface tilt angle and the height of key bottom points; acquiring 3D topographic data of the PCB pads, including pad surface height differences; spatially fusing the component's posture data and the pad topographic data to plan a dynamic compensation trajectory; during the mounting head's descent, a force sensor collects real-time contact force feedback values, and the controller adjusts the Z-axis descent speed and final stopping position in a closed loop according to a preset pressure target curve to complete the mounting. This invention, by introducing 3D vision perception and pressure closed-loop control, solves the problem of uneven mounting pressure and component damage caused by the inability of existing 2D vision-based surface mount machines to perceive 3D component posture deviations, achieving high-precision, low-stress, and high-reliability mounting of SMD LEDs.

The utility model relates to the technical field of SMT initial workpiece detection, in particular to SMT intelligent initial workpiece testing equipment which comprises a rack, a rotary clamping device, a feeding frame, a discharging frame, an LCR tester, a testing probe and a material moving device, and the rotary clamping device, the feeding frame, the discharging frame and the material moving device are arranged on the rack respectively. And the test probe is arranged on the material moving device and is electrically connected with the LCR tester. According to the SMT intelligent first workpiece testing equipment, manual participation steps are reduced, the working efficiency of SMT first workpiece detection is improved, and meanwhile, the conditions of wrong detection and missing detection are avoided.

The utility model discloses a PCB (Printed Circuit Board) placing rack for SMT (Surface Mount Technology), which relates to the technical field of PCB placing racks and comprises a box body and a top plate, two fixing rods are fixedly connected between one end of the box body and one end of the top plate, a side plate is fixedly connected between the other end of the box body and the other end of the top plate, and the fixing rods are fixedly connected with the side plate. A first supporting plate is fixedly connected between the two fixing rods, a second supporting plate is slidably arranged between the box body and the top plate through a power assembly, a plurality of T-shaped grooves distributed at equal intervals are formed in the faces, close to each other, of the first supporting plate and the second supporting plate, and T-shaped plates are slidably arranged in the T-shaped grooves. A pull ring is fixedly arranged at the end of the T-shaped plate, and a limiting block is fixedly arranged at the end, movably extending out of the T-shaped groove, of the T-shaped plate. According to the utility model, the PCBs with different sizes can be placed in a limited manner, and the problems that the PCBs with different sizes cannot be placed on the existing PCB placement rack for the SMT process, and the application range is relatively limited are solved.