Overview
Solder Paste Inspection (SPI) is a pre-placement quality control process in the SMT assembly line, which is the core gate to control the final soldering quality of the assembled board. It uses a high-precision 3D optical imaging system to conduct a full inspection of the solder paste printed on the PCB pads, to verify whether the solder paste printing quality meets the process requirements. As more than 70% of SMT assembly defects are caused by poor solder paste printing, this process intercepts printing defects before component placement, fundamentally improving the soldering yield and ensuring the long-term reliability of solder joints. All SPI operations strictly follow IPC-A-610 international standards.
3D Inspection Execution Standard
A high-precision 3D optical imaging system is used to capture full-dimensional data of the printed solder paste
Inspection is executed for each pad on the PCB, with 100% full coverage of all printed pads
Inspection standards are formulated according to IPC-A-610 international standards and component package specifications
Inspection parameters are adjustable according to the solder paste type, stencil design, and process requirements
2D and 3D dual-mode inspection is supported, to ensure the accuracy of defect identification
Full-Parameter Inspection Scope
Solder paste volume measurement for each pad
Solder paste printing height consistency inspection
Solder paste printing area coverage verification
Solder paste printing alignment accuracy inspection
Solder paste shape and uniformity inspection
Solder paste bridging and continuous printing defect inspection
Missing print and insufficient print defect inspection
Solder paste drawing and slump defect inspection
Pre-Placement Defect Interception Mechanism
SPI inspection is executed immediately after solder paste printing, before component placement
Critical defects such as solder paste bridging and serious missing print will trigger an immediate pause of the production line
Non-conforming panels are automatically transferred to the rework station, and will not enter the placement process
Defect data is synchronized to the printing operator in real time, to adjust printing parameters immediately
Continuous occurrence of similar defects will trigger a full process review and stencil inspection
Real-Time Printing Process Optimization
Printing defect data is statistically analyzed in real time, to identify fluctuations in the printing process
Printing parameters such as scraper speed, pressure, and printing speed are adjusted according to defect feedback
Stencil cleaning frequency and method are optimized based on the residual defect data
Solder paste type and viscosity are verified and adjusted according to the printing effect
The optimized process parameters are recorded and archived, to form a standardized process database for different products
Batch Consistency Monitoring System
Printing quality data of each panel in the batch is recorded and archived
Batch consistency of solder paste printing parameters is monitored in real time, to identify process drift
Process capability index of the printing process is calculated regularly, to evaluate the stability of the process
Long-term statistical analysis of printing defect data is carried out, to continuously optimize the stencil design and printing process
Batch printing quality reports are generated, which can be provided to customers upon request
