Abstract: A system has a projection lens directing on-axis light and low level LEDs directing light to blind microvias. A high resolution camera captures blind microvia images and an image processor recognizes defects according to classifications according to reflected light area and centroid position. The lens is telecentric for particularly effective image capture in blind microvias. The system also has an array of 6000 back lighting LEDs providing illumination for capture of images by a camera. These images are analyzed by the image processor to detect defects such as blocked through microvias.

Abstract: A system (1) has a projection lens (12) directing on-axis light and low level LEDs (18) directing light to blind microvias (5). A high resolution camera (14) captures blind microvia images and an image processor recognizes defects according to classifications (54-59) according to reflected light area and centroid position. The lens (12) is telecentric for particularly effective image capture in blind microvias (5). The system also has an array of 6000 back lighting LEDs (10) providing illumination for capture of images by a camera (15). These images are analyzed by the image processor to detect defects such as blocked through microvias.