LED Module Test Pad Design for Real-Time Defect Detection

The patent applies preliminary action by incorporating test pads and test wiring layers into the substrate before LED mounting. This allows inspection operations to be performed before the LED is mounted, enabling defect detection in the substrate, wiring layers, and test pads themselves. The test structure is prepared in advance, so when inspection is needed, the pathway for testing already exists, eliminating the need for complex post-assembly inspection equipment.

The patent uses test pads and test wiring layers as intermediary elements that facilitate defect detection. These intermediaries provide accessible test points on the substrate surface that connect to internal wiring and components. By measuring electrical properties at these intermediary test points, defects in the underlying structure can be detected without requiring direct access to or complex inspection of the internal wiring and components.

The patent replaces mechanical measurement and physical marking methods with electrical measurement for defining and controlling the active area boundary. Instead of using mechanical tools to measure and mark the active area perimeter, the invention uses electrical signals applied through test pads to detect the boundary where the active area meets the non-active area. This electrical approach provides higher precision and eliminates the complexity of mechanical measurement systems.

The patent changes the measurement parameter from physical/dimensional measurement to electrical property measurement. By measuring electrical properties (such as capacitance or resistance) at the test pads, the active area boundary can be precisely identified based on electrical signal characteristics rather than physical dimensions. This parameter change enables precise control of active area size through electrical means, simplifying the manufacturing process while improving precision.