<title>Advanced pattern inspection using Macroview</title>

Abstract

The new pattern inspection algorithm we developed detects fatal defects on printed wiring boards. The algorithm determines whether patterns identified by an automated pattern inspection (AOl) system are actually defective by considering the electrical malfunction that the defect will cause. A macroscopic model based on the pattern design rules and their tolerances to pattern violations is needed to evaluate defects. The algorithm classifies features around a defective pattern into 50 categories and compares the defect distribution with preset check rules. The automated optical verification system we developed captures pattern images with a CCD camera and uses verification software to evaluate defects. The process takes 10 seconds per image. We tested the system on the factory floor, and it detected all defects with less than 4.8% of false alarms.

Automated verification technology using CAD data

“…Because the brightness of the fluorescence depends on the substrate thickness, the received brightness varies over the substrate. A floating threshold can be used to obtain a binary pattern signal [7]. In our approach, the threshold level changes corresponding to the variation in brightness.…”