The SMT (Surface Mount Technology) processing line is the core production line for electronic manufacturing to achieve automated component mounting, soldering, and testing. Its equipment configuration needs to cover the entire process of “substrate preparation – component mounting – soldering curing – testing and repair – finished product sorting”. The following is a detailed description of the essential core equipment and auxiliary equipment for each stage, taking into account both basic production needs and quality control requirements.
1、 Core production equipment (mainline equipment)
The core production equipment is the core framework that constitutes the SMT assembly line, directly determining production efficiency, mounting accuracy, and product qualification rate. It is configured in sequence according to the production process:
1. Substrate cleaning/drying equipment
Function: Remove dust, oil stains, static electricity and other impurities from the surface of PCB (printed circuit board) to avoid affecting the stability of solder paste printing or component mounting; If the PCB is damp, it needs to be removed by drying equipment to prevent problems such as solder beads and virtual soldering during soldering.
Common types: PCB electrostatic precipitator, hot air drying oven. The electrostatic precipitator adopts a combination of ion air electrostatic removal and brush cleaning, which is suitable for mass production; The drying oven needs to have a constant temperature control function, with a temperature range generally adjustable between 60-120 ℃.
2. Solder paste printing equipment
Function: Accurately print solder paste (a mixture of solder powder and flux) onto the solder pads of PCB, providing a “connecting medium” for subsequent component soldering. The printing accuracy directly affects the soldering quality of the mounted components.
Core equipment: Fully automatic screen printing machine (including steel mesh positioning system, PCB positioning platform, scraper system). Key configuration requirements: Visual alignment function (ensuring precise alignment between steel mesh and PCB pads), adjustable scraper pressure/speed (suitable for different thicknesses of PCB and solder paste types), solder paste stirring function (preventing solder paste precipitation). Auxiliary accessories: Steel mesh (customized according to PCB pad patterns), solder paste mixer.
3. Component mounting equipment
Function: Remove SMT components (resistors, capacitors, inductors, chips, etc.) from the tape/tray and accurately mount them onto the printed solder paste PCB pads. This is the core link of the SMT assembly line, determining the mounting efficiency and accuracy.
Common types and applicable scenarios:
High speed surface mount machine: focuses on mounting efficiency and is suitable for mounting small passive components (resistors, capacitors) such as 0402 and 0603. The mounting speed can reach 10000-60000 points/hour and is suitable for large-scale production.
High precision surface mount machine (universal machine): It focuses on mounting accuracy and is suitable for mounting precision components such as QFP, BGA, IC, etc. The mounting accuracy can reach within ± 0.03mm. Some models have dual mounting heads, which can balance efficiency and accuracy.
Multi functional SMT machine: compatible with various packaging types of components (from passive components to precision chips), suitable for small batch and multi variety production needs, with high flexibility.
Key configurations: Visual recognition system (CCD camera, accurately identifying component and PCB pad positions), multiple suction nozzles (adapted to different sizes of components), material rack (storing material strips/trays, divided into different specifications such as 8mm, 12mm, 16mm, etc.).
4. Welding equipment
Function: Melt the solder paste printed on the solder pad through high temperature, and firmly connect the component pins to the PCB solder pad after cooling, achieving electrical conductivity and mechanical fixation. It is the core link to permanently bond the “mounted components” with the PCB.
Mainstream equipment: Reflow soldering furnace (hot air reflow soldering), replacing traditional wave soldering (more suitable for surface mount components). Working principle: The PCB passes through the preheating zone (removing moisture and flux volatiles from the solder paste), the heating zone (gradually heating up the solder paste), the soldering zone (reaching the melting point of the solder paste, generally above 217 ℃, where the solder paste melts and wets the solder pads and component pins), and the cooling zone (solder solidification, completing soldering) along with the conveyor belt.
Key configuration requirements: Multi temperature zone control (generally 6-10 temperature zones, ensuring smooth transition of temperature curve), adjustable temperature curve (suitable for different types of solder paste and heat resistance requirements of components), hot air circulation system (ensuring uniform surface temperature of PCB), adjustable conveyor speed.
5. Testing equipment
Function: To detect whether there are welding defects (such as virtual soldering, solder leakage, solder balls, bridge connections, component misalignment/reverse pasting, etc.) in the PCB after welding, timely screen out defective products, and prevent defective products from flowing into subsequent processes. It is the core equipment of quality control.
Common types and functions:
AOI detection equipment (automatic optical detection): By capturing PCB images with high-definition cameras and comparing them with standard images, it automatically identifies appearance defects (such as solder balls, bridge connections, solder leaks, and component offsets), adapts to batch detection, has fast detection speed, and can set different detection accuracy levels.
X-Ray inspection equipment: For internal defects that cannot be detected by AOI (such as virtual soldering and voids at the bottom of BGA chips), X-rays penetrate PCBs and components to clearly display the welding interface status. It is an essential equipment for detecting the welding quality of precision chips.
Online testing instrument (ICT): By contacting the test points on the PCB with probes, it detects the continuity of the circuit, whether the component parameters (such as resistance and capacitance values) are qualified, and checks for electrical performance defects.
2、 Auxiliary equipment (ensuring smooth operation of the assembly line)
Although auxiliary equipment does not directly participate in the core production process, it can improve production efficiency, ensure production safety and product quality, and is an indispensable supplement to SMT assembly lines
1. Conveyor and positioning equipment
Docking station: Connect various core equipment (such as screen printing machine and surface mount machine, surface mount machine and reflow soldering furnace) to achieve smooth transition and transportation of PCBs. Some docking stations have PCB caching function to avoid pipeline congestion.
Positioning fixture: ensures precise positioning of PCBs in various devices, adapts to PCBs of different sizes, and generally adopts adjustable design.
Conveyor belt speed control system: Unify the conveying speed of each equipment to ensure consistent production rhythm.
2. Electrostatic protection equipment
SMT components (especially chips) are sensitive to static electricity, which may cause damage to the components. Therefore, it is necessary to take full precautions against static electricity throughout the process:
Anti static workbench: Reduce the accumulation of static electricity on the workbench.
Anti static wristband/anti-static clothing: worn by operators to introduce static electricity from the human body into the ground.
Ionic fan: Eliminate static electricity on the surface of PCB and components.
Anti static material box/rack: stores components and PCBs to be processed to avoid static electricity during transportation.
3. Repair equipment
Repair the detected defective products to reduce production costs:
Hot air repair table: By using adjustable temperature hot air, the defective components are precisely heated to melt the solder and then removed. New components are then reattached and soldered, making it suitable for repairing various surface mounted components.
BGA rework station: specifically designed for the rework of BGA chips, with precise temperature control and alignment functions to avoid damage to chips or PCBs during the rework process.
Solder paste dispensing pen: used to replenish solder paste or repair local solder paste defects.
4. Material storage and management equipment
Component rack/cabinet: Classify and store component tapes and trays to avoid confusion. Some cabinets have moisture-proof functions (such as moisture-proof boxes, storing humidity sensitive components).
Solder paste refrigerator: Solder paste needs to be stored at low temperatures (0-10 ℃) to maintain performance. The refrigerator can accurately control the temperature to avoid solder paste deterioration.
Material Management System (optional): Through barcode or RFID technology, realize the management and traceability of electronic components in and out of the warehouse, and adapt to large-scale and multi variety production.
5. Other auxiliary equipment
Air compressor: provides compressed air for equipment such as screen printing machines and surface mount machines, driving pneumatic components to operate.
Dehumidifier/air conditioner: Control the temperature and humidity in the production workshop (generally requiring a temperature of 22-26 ℃ and a humidity of 40% -60%) to avoid abnormal temperature and humidity affecting the performance and mounting accuracy of solder paste.
Waste collection box: Collect strip waste, solder paste residue, etc. generated during the production process to maintain a clean production environment.
3、 Core principles of equipment configuration
1. Matching production scale: Small batch and multi variety production can be configured with 1 multi-functional surface mount machine+basic testing equipment; Large scale production requires a combination of high-speed surface mount machines and high-precision surface mount machines to improve efficiency.
2. Types of compatible components: If precision chips such as BGA and QFP are involved, X-ray testing equipment and BGA rework stations need to be configured; If passive components are the main focus, emphasis can be placed on high-speed surface mount machines and AOI testing.
3. Ensure quality control: At least one AOI testing equipment should be equipped, and X-ray testing should be added to critical processes (such as precision chip mounting) to avoid the outflow of defective products.
4. Consider scalability: Reserve a certain amount of adaptation space when selecting equipment, which can be compatible with larger PCB sizes or more packaging types of components, to meet the changes in future production needs.
We focus on providing the following SMT equipment production solutions for electronic manufacturers:
Printing machine, SPI, SMT machine AOI、 Reflow soldering, X-Ray and other SMT production line equipment;
SMT peripheral equipment such as loading and unloading machines, connecting tables, coating machines, dispensing machines, and material receiving machines;
Feida, suction nozzle, board, air valve, belt, spare parts, consumables and other services and solutions.