1、 Production line process and spatial layout planning
Following the logical sequence of SMT core process flow “solder paste printing → SPI inspection → surface mounting → reflow soldering → AOI inspection”, plan a linear layout to reduce material handling losses. Set up a DEK solder paste printing machine workstation in the front-end, equipped with a constant temperature and humidity storage cabinet to store solder paste, ensuring stable viscosity of solder paste before printing; Adjacent to the printing machine, the Benchuang SPI (solder paste inspection) equipment is installed to achieve real-time monitoring of printing quality and prevent unqualified solder paste from flowing into the next stage. The inspection data is synchronized with the MES system for easy traceability and analysis.
Deploy Siemens SMT machines in the core SMT area of the middle section, and configure 1-2 high-speed SMT machines (such as Siemens X series) and 1 multifunctional SMT machine (such as Siemens F series) according to production capacity requirements, forming a “high-speed+multifunctional” combination that meets the requirements of high-density and irregular component mounting. Reserve a buffer area of 5-8 meters between the SMT machine and the Heller reflow soldering furnace, and equip it with an anti-static conveyor belt to avoid component displacement of the PCB board due to transmission congestion after SMT; The reflow soldering furnace adopts a segmented temperature control design, with 8-10 temperature zone curves pre-set according to different solder joint requirements. A cooling section is set behind the furnace to ensure the stability of the welded components.
The backend inspection process is adjacent to the reflow soldering furnace and equipped with Benchuang AOI (Automatic Optical Inspection) equipment. It adopts a double-sided inspection mode to cover defects such as solder joint voids, component errors/leaks, etc., with a detection accuracy of 0.01mm. Non conforming products are guided into the repair area through a diversion track to avoid mixing and affecting subsequent production. The overall production line reserves a 1.2-meter-wide channel for equipment maintenance and personnel operation, while dividing the raw material area, finished product area, and repair area to achieve material zoning management.
2、 Establishment of Quality Control System
Based on the principle of “prevention first, full process monitoring”, establish a full process quality control mechanism. During the DEK printing machine stage, 3-5 PCBs are sampled and tested per hour using SPI equipment to monitor solder paste thickness (controlled within ± 10% standard value) and area coverage (≥ 95%). An alarm is automatically triggered in case of abnormalities, and the printing machine is linked to adjust scraper pressure and speed parameters; The Siemens surface mount machine is equipped with a visual positioning system, with a component recognition accuracy of 0.005mm. Before mounting, the component packaging library is verified to avoid material errors. At the same time, after the first piece of production in each shift, it needs to undergo AOI full inspection to confirm that the mounting parameters are correct before mass production can be carried out.
During the Heller reflow soldering stage, real-time monitoring of the temperature curve inside the furnace is carried out, and temperature zone data is recorded every 4 hours to ensure that the peak welding temperature (235-250 ℃) and insulation time (60-90s) meet IPC standards; The AOI testing process is equipped with a dual audit mechanism. PCBs judged as unqualified by the machine need to be manually reviewed and repaired before passing the AOI testing again to ensure that the defect rate is controlled below 0.1%. In addition, SPI and AOI equipment are calibrated regularly (once a month), and wear tests are conducted on DEK printing machine scrapers and Siemens surface mount machine nozzles (once every two weeks) to ensure stable quality from the perspective of equipment accuracy.
3、 Efficiency and Cost Optimization Strategies
Improve production efficiency through device linkage and capacity balance. Based on the MES system, data exchange between various devices is achieved, and production is automatically scheduled according to order requirements. For example, when the DEK printing machine completes a batch of PCBs, the system synchronizes instructions to the SPI device to start detection. After passing the detection, it is automatically transmitted to the surface mounting machine to reduce waiting time; For different product types, preset equipment parameter templates (such as printing pressure, mounting speed, reflow soldering curve) are used to shorten the changeover time from traditional 30 minutes to less than 15 minutes.
In terms of cost control, optimize the amount of solder paste used, accurately control the scraper stroke through the DEK printing machine, and reduce solder paste waste (target reduction of 5% loss); Siemens surface mount machine adopts the strategy of “batch mounting+priority mounting of high-value components” to reduce the component scrap rate (controlled below 0.3%); The Heller reflow soldering furnace adopts energy-saving mode, automatically reducing the temperature in the temperature zone during non production periods to reduce energy consumption (expected to save 10% of electricity bills per month). At the same time, establish a preventive maintenance plan for equipment to reduce downtime caused by sudden failures (target monthly downtime rate ≤ 2%) and ensure the continuous and stable operation of the production line.
4、 Personnel and Safety Management
Configure a professional operation and maintenance team, including 1 production line supervisor (responsible for overall coordination), 2 equipment engineers (responsible for the maintenance of surface mount machines and reflow soldering furnaces respectively), and 3 operators (responsible for printing, testing, and repair). All personnel must undergo training and pass the equipment manufacturer before they can take up their posts, and regular skill assessments are conducted (once every quarter). In terms of safety management, anti-static grounding devices are installed in the production line area, and operators wear anti-static wristbands and anti-static clothing; The emergency stop button and warning signs of the equipment are complete. Weekly safety inspections are carried out, with a focus on checking the smoke exhaust system and equipment circuit safety of the reflow soldering furnace to ensure compliance with safety production standards.