SMT Production Line Analysis SMT production line to achieve * the maximum output, it is necessary to consider the efficiency of the production line. The SMT machine is the key equipment in the SMT production line, so it is very important to improve the production efficiency of the SMT machine. Relevant methods and measures have been summarized and have been implemented to substantially improve production efficiency. The main methods and measures are as follows: (1) PCB design process; (2) production line balance; (3) equipment program optimization; (4) management measures; (5) improve the accuracy of new program preparation; (6) good equipment monitoring and maintenance In addition, understanding the SMT production process is also very important, the following is introduced.   Basic process components include: screen printing (or dispensing), placement (curing), reflow soldering, cleaning, testing, rework    1、Silkscreen printing: its role is the solder paste or patch adhesive leakage printed on the pads of the PCB, in preparation for the welding of components. The equipment used for screen printing machine (screen printer), the printer is located in the front of the SMT production line *.    2, dispensing: it is the glue drops to the PCB's fixed position, its main role is to fix the components to the PCB board. The equipment used is the dispensing machine, located in the front of the SMT production line * or behind the testing equipment.    3、Placement: Its role is to accurately install the surface assembly components to the PCB's fixed position. The equipment used is the mounter, located in the SMT production line behind the screen printing machine.    4、Reflow soldering: its role is to melt the solder paste, so that the surface assembly components and PCB board firmly bonded together. The equipment used is reflow oven, located in the SMT production line behind the mounting machine.    5, cleaning: its role is to assemble the PCB board above the harmful welding residues such as flux removed. The equipment used for cleaning machine, the location can not be fixed, can be online, or not online.    6, testing: its role is to assemble the PCB board for the quality of welding and assembly quality testing. The equipment used are magnifying glass, microscope, online tester (ICT), flying probe tester, automatic optical inspection (AOI), X-RAY inspection system, functional tester, etc. Location according to the needs of detection, can be configured in the production line appropriate place.    7, rework: its role is to detect the failure of the PCB board rework. The tools used are soldering iron, reworking workstation, etc. Configured in any position in the production line. Such as BGA rework table. Translated with www.DeepL.com/Translator (free version)

Evaluation of a placement machine vision system for SMD placement alignment I. Support for multiple types of cameras    Previously the time to process images has always been longer than the time to acquire them, but new developments in CPU technology have accelerated image processing, and image acquisition speed may instead become a limiting factor. In order to improve system processing efficiency, to reduce the time to acquire images to a * low degree, the vision system should be able to support a variety of advanced line scan, high resolution (1024 × 1024 pixels), high-speed digital cameras.   Second, identify non-standard device capability    Machine vision systems should be able to reliably identify the shape of various non-standard devices, regardless of how rare they are. The existing patch alignment software, with built-in geometric pattern finding tools, these tools can "learn" the geometric properties of the device, even if it is oddly shaped, the system can identify the device.   Three, the ability to reliably avoid the nozzle    SMD component placement generally uses either front lighting or backlighting, or both. Backlighting is used to produce a back image of the device, revealing an image similar to a binary image, making it easier for the vision system to identify the device, and this type of lighting is often used when identifying simple devices such as chip resistive capacitors. However, backlighting can also pose a problem for the vision system: the back image of the pickup device's nozzle often protrudes from the back of the device or partially obscures the chip (e.g., Figure 10). While frontal illumination techniques can prevent this phenomenon, the pixel grayscale values of the nozzle itself may prevent the vision system from reliably distinguishing between the nozzle and the device. Choosing a vision system that can recognize the difference in shape between the device and the pick-up device's nozzle, such a system can tolerate partial masking of the nozzle and therefore will improve device alignment accuracy and prevent devices from being misplaced due to visual errors.   IV. Ability to identify closely spaced devices and white ceramic surface devices    In order to **identify various devices such as BGAs, flip-chips or CSPs, and to check for pin deviations, the vision system should reliably identify white ceramic surface devices, whose low-contrast reflective nature would render conventional vision techniques useless. The vision system must also be able to accurately locate each component. These functions should be verified, and the test software should be able to distinguish between individual objects.   V. Ability to automate programming   For very special components, new vision software tools should have the ability to automatically "learn", the user does not have to manually input parameters into the system to create a device description from scratch, they just need to take a picture of the device to the vision camera can be, the system will automatically produce a comprehensive description similar to CAD. This technology can improve the accuracy of device descriptions and reduce many operator errors, speed up the creation of component libraries, especially in the case of frequent introduction of new devices or the use of uniquely shaped devices, thereby improving production efficiency.   Six, the ability to reliably determine the location of the PCB reference mark    Since reliable positioning of PCB reference marks is the **step** to any SMD placement alignment, the vision system must be able to identify different references, even in conditions where the appearance of the reference is not ideal. For example, variations in oxidation, tinning, and wave solder from the manufacturing process can cause specular reflections and surface inconsistencies that can dramatically change the appearance of the marker. Other factors that may affect the appearance of the reference include board distortion, excessive solder buildup, board color changes, and more. A vision system that tolerates these conditions can help users improve alignment success and reduce operator intervention.     Taking these factors into account ensures that you can easily handle new component types and different devices from different manufacturers, and that the system you choose is highly flexible, making the user's job easier.

Common structure of SMD machine The structure of SMD machine can be divided into 4 types of structure: compound type, arch type, turret type and large parallel system. 1、Compound type. Composite machine is developed from the arch type machine, it combines the features of turret type and arch type, there are turntables installed on the movable arm, like Siemens' Siplace 80S25 bonder, there are two rotary heads with 12 nozzles. Since the compound machine can increase the speed by increasing the number of movable arms, it has more flexibility, so its development prospect is favored, such as Siemens introduced the HS60 machine is installed with four rotary head, placement speed of up to 60,000 pieces per hour. universal also introduced the rotary head with 30 nozzles, called " Lightning Head", two such rotary heads mounted on the Genesis placement platform, can achieve a placement speed of 60,000 pieces per hour. In a strict sense, the composite machine still belongs to the moving arm structure.   2、Arch type. Arch-frame (also known as moving arm) machines are *traditional* bonder machines with better flexibility and accuracy for most components, high precision machines are generally of this type, but their speed cannot be compared with compound, turret and mega parallel systems. The arch type machine is divided into single arm type and multi-arm type. The single arm type is the *early developed multifunctional bonder still in use today. The dobby mounter developed on the basis of the single-arm type can increase the work efficiency exponentially, such as the GSM2 mounter of Universal Corporation in the United States has two movable arm mounting heads, which can alternately mount two PCBs (PrintCircuitBoard) at the same time. The majority of bonder manufacturers have introduced high-precision bonder and medium-speed bonder with this structure, such as AC72 from Universal, AQ-1 from Assembleon, TIM-X from Hitachi, QP-341E and XP series from Fuji, BM221 from Panasonic, and BM221 from Samsung. BM221, CP60 series from Samsung of Korea, YV series from Yamaha of Japan, and KE series from Juki of Japan. However, the component arrangement is increasingly concentrated on active parts, such as leaded QFP (Quadflat package, Quadrilateral flat package device) and BGA (Ball gridarray, Ball grid array device), where mounting accuracy plays a vital role in high yield. Composite, turret and large parallel systems are generally not suitable for this type of component mounting.   3. Turret type. Turret type machines are mainly used in the production of large-scale computer boards, cell phones, home appliances and other products, this is because in these products, resistive components are particularly large, high assembly density, very suitable for ** with this model for production. A considerable number of Taiwan-invested, Hong Kong-invested electronic assembly enterprises and domestic electrical manufacturers are using this model to meet the requirements of high-speed assembly. The concept of the turret is to use a set of moving feeders from which the turret picks up components and then places them on top of the circuit board located on a moving table. The turret type machine makes the placement speed increase significantly due to the simultaneous picking up of components and placement action. This kind of structure high speed mount machine in our country's application is also very common, not only the speed is fast, and after more than ten years of development technology has been very mature, such as Fuji company's CP842E machine mount speed can reach 0.068 seconds / piece. But this kind of machine because the mechanical structure is limited, its pasting speed has reached a limit value, not possible to improve greatly again. The shortcoming of this model is only can deal with the strip material.   4、Massive parallel system. Large-scale parallel system (also called module machine) uses a series of small individual placement unit (also called module). Each unit has its own filament position system, mounted with a camera and a mounting head. For example, Assembleon's AX-5 machine can* have up to 20 placement heads, achieving a placement speed of 150,000 pieces per hour, which is considered to be the industry**, but for each placement head, the placement speed is around 7,500 pieces per hour, and there is still a possibility of substantial improvement. This type of machine is also mainly suitable for large-scale production, such as cell phones. The manufacturer who produces the mass parallel system type machine mainly has Assembleon, Fuji also launched the NXT type super high speed mounter which adopts the similar structure, by carrying the mount work head which can be changed, the same machine can be both the high speed machine and the universal machine, almost can carry out the mount of all mount components, thus the initial investment of the equipment and the increase equipment investment is reduced to * Low degree. Each place

Instructions for buying reflow soldering At present, electronic product PCB boards continue to miniaturize, chip components appear, the traditional welding method can not adapt to industry requirements. With SMT the whole technical development is becoming more and more perfect, a variety of chip components (SMC) and mount devices (SMD) appear, as part of the placement technology reflow soldering process technology and equipment has also been developed accordingly Then buy reflow soldering to understand which parameters? Affect the quality of reflow soldering have the following main parameters. 1. temperature control accuracy should be in the soil 0.1 ~ 0.2 ℃; (temperature sensor sensitivity to meet the requirements). 2. The width of the conveyor belt to meet the * large PCB size requirements. 3. The lateral temperature difference of the conveyor belt should be less than 5℃, otherwise it is difficult to ensure the quality of welding. 4. should have a temperature curve test function, if the equipment does not have this configuration, should be purchased outside the temperature curve collector. 5. The longer the length of the heating zone, the more the number of heating zones, the easier it is to adjust and control the temperature curve. General small and medium-sized production selection of 4-5 temperature zones, heating zone length of about 1.8m reflow furnace that can meet the requirements. In addition, the upper and lower heaters should be independent temperature control, in order to adjust and control the temperature curve. 6. Conveyor operation should be smooth, conveyor vibration will cause displacement, suspension bridge, cold welding and other welding defects. 7.* The high heating temperature is generally 300~350℃, if lead-free solder or metal substrate is considered, more than 350℃ should be selected.

Vision Alignment System for Laminating Machine The performance of CCD hardware currently used in chip machine lenses is of a comparable level. In the CCD hardware development earlier developed "Back-Lighting" (Back-Lighting) and "Front-Lighting" (Front-Lighting) technology and programmable lighting control to better cope with different component placement needs. Light" (Front-Lighting) technology, as well as programmable lighting control, to better cope with a variety of different component placement needs. For example, simple components such as resistors and capacitors are illuminated from behind, and the vision system can reliably align them by simply recognizing the body outline. Conversely, dense-pin components such as QFPs* are better illuminated from the front, showing the complete distribution of pins around the package so that the vision system can reliably identify the alignment. Some BGAs have visible alignments on the bottom side of the component that can confuse the vision system, and these components require a side lighting system. It will illuminate the solder balls from the side instead of the alignment on the bottom side, so the vision system can check the solder ball distribution and correctly identify the component.            The highly** optical unit, flexible illumination and high resolution camera integrate the *optimal* image of the circuit and device, so that the feedback needed to correct board, component and feeder changes can be obtained by modern algorithms that are vital. Vision systems play an important role in successful placement equipment. By using advanced vision technology devices, higher levels of placement rates can be achieved. Defects occurring in pick-up are reduced, thus contributing to increased production on the entire production line and increased economic efficiency. Vision systems are generally classified as overhead, elevation, head or laser aligned, depending on the location or type of camera.   (1) elevation camera is used to detect components in a fixed position, generally using CCD technology, before installation, the components must be moved over the camera in order to do visual alignment process. Roughly speaking, it seems to be a bit time-consuming. However, since the mounting head must be moved to the feeder to collect the components, if the camera is mounted between the pick-up position (from the feeder) and the mounting position (on the board), the vision acquisition and processing can be done simultaneously during the movement of the mounting head, thus shortening the mounting time.   (2) The overhead camera is mounted on the mounting head and is used to search for targets (called references) on the board in order to place the board in the correct position prior to placement.   (3) Laser alignment is to generate a moderate beam from a light source and shine it on the component to measure the impact of component projection. This method measures the size and shape of the component as well as the deviation of the center axis of the nozzle. This method is fast, because it does not require walking over the camera. However, its main drawback is that it can not pin and dense-pin components for pin inspection, for sheet components is a good choice. 90's laser alignment technology was introduced only to deal with 7´7mm components, the current ** generation of laser alignment system introduced by Anbion to deal with component size increased to 18´18mm, the laser technology can identify more shapes, the accuracy has also improved significantly.   (4) the head camera is installed directly in the mount head, generally uses the line-sensor technology, in the process of picking up the component to move to the designated position to complete the detection of the component, this technology is also called "the flight alignment technology", it can greatly improve the mount efficiency. The system is composed of two modules: one module is the light source module composed of light source and lens. The light source adopts LED light-emitting diode and scattering lens, and the light source lens forms the light source module. Another module is accepting module, using LineCCD and a set of optical lens to form accepting module. These two modules are installed on both sides of the chip head spindle, with the spindle and other components to form the chip head, the chip machine has several chip head, there will be a corresponding set of several systems.