SIG OMM (Optical Measurement Machine): Precision Geometric Dimension Measurement Across the Entire PCB Manufacturing Process

In PCB (Printed Circuit Board) manufacturing, dimensional accuracy directly determines electrical performance and assembly reliability. From drilling and circuit etching to soldermask printing and surface mounting, every process step carries specific geometric dimension measurement requirements. SIG OMM (Optical Measurement Machine) delivers non-contact, high-precision optical measurement technology throughout the entire PCB manufacturing workflow, providing accurate dimensional data support for each critical stage.

Drilling Process: Hole Diameter and Positional Accuracy Control

Drilling is the first critical process in PCB manufacturing – positional deviations can directly lead to interlayer short circuits or open circuits. SIG Vision Measuring System precisely measures the diameter of through-holes (PTH) and blind vias (VIA), hole center coordinates, and hole-to-hole spacing. For high-density multilayer boards, the equipment uses coaxial illumination to penetrate translucent soldermask layers, clearly capturing underlying hole contours and ensuring interlayer registration deviation is controlled within acceptable limits. Additionally, the system measures pad (annular ring) integrity, effectively identifying defects such as wall cracks or missing copper rings.

Circuit Etching Process: Line Width, Line Spacing, and Defect Detection

The accuracy of circuit patterns is fundamental to PCB functionality. SIG Vision Measuring Machine performs precision measurement of line width and line spacing after etching, meeting the inspection requirements of fine-pitch PCB products. Equipped with a high-resolution industrial camera and telecentric optical system, combined with intelligent edge-finding algorithms, the system quickly identifies subtle defects such as open circuits (broken traces), short circuits (bridging), notches, and pinholes. At the same time, the equipment measures pad diameter and positional accuracy, ensuring pad dimensions comply with design specifications.

Soldermask and Surface Finishing Process: Soldermask Registration Offset and Surface Quality Assessment

Soldermask printing quality directly affects soldering reliability. SIG Vision Measuring System's high-magnification optical lens and high-definition imaging system enable visual inspection of soldermask registration offset and pad exposure issues. The system also provides indirect evaluation of soldermask thickness to ensure surface quality meets standards. For surface-finished areas such as gold fingers, the equipment precisely measures gold finger width and positional accuracy, safeguarding signal transmission reliability.

Lamination and Final Shaping Process: Board Thickness, Flatness, and Warpage Measurement

In the lamination process, warpage deformation caused by differences in material expansion coefficients is a major quality challenge in PCB manufacturing. SIG Vision Measuring System, optionally equipped with a laser probe or white-light confocal sensor, automatically scans multi-point height data, calculates flatness values, and outputs color deviation maps to precisely analyze overall plane deformation and warpage of large-format PCB boards. The system also measures board thickness uniformity, ensuring finished board thickness complies with specifications. In the final shaping stage, the equipment measures PCB outline length/width, edge clearance, and profile dimensions, guaranteeing dimensional accuracy of individual boards after panel depaneling.

Pre-SMT Process: Pad and Stencil Aperture Inspection

Prior to surface mount technology (SMT), pad solderability and stencil aperture accuracy directly impact solder paste printing quality. SIG Vision Measuring System measures pad dimensions and positional accuracy, ensuring pads are free from misalignment, oxidation, or contamination. For SMT stencils, the system verifies aperture size, shape, and positional accuracy, controlling solder paste printing quality at the source.

Pre-Shipment Final Inspection: Full Dimensional Final Inspection and SPC Statistical Analysis

Before PCB finished goods are shipped, SIG fully automatic Vision Measuring Machine pre-sets measurement paths for unattended batch scanning – one-click start automatically completes dimensional measurement of multiple workpieces. Measurement results are automatically uploaded and SPC statistical analysis reports are generated to monitor production line process capability in real time, providing early warning of potential batch defects. The system supports CAD drawing import and automatic programming – operators can generate measurement programs with one click from design drawings, enabling automated inspection of same-batch products.

Conclusion

From drilling to pre-shipment final inspection, SIG Vision Measuring System (OMM – Optical Measurement Machine) runs through the entire PCB manufacturing process, delivering precise, efficient, non-contact dimensional measurement support for every critical stage. Whether rigid PCB, flexible FPC, or rigid-flex boards, the equipment adapts to workpieces of different materials and sizes, meeting diverse needs from laboratory small-batch inspection to factory high-volume production. As PCB manufacturing continues to evolve toward higher density and finer pitch, SIG – backed by Sinowon's precision measurement expertise – empowers PCB manufacturers to upgrade quality control from "sampling inspection" to "100% full inspection."