Yoshikazu Kakinoki

Advanced pattern inspection using Macroview

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 (AOI) 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 percent of false alarms.

Visual inspection system using multidirectional 3-D imager

This paper describes a visual inspection system for factory automation. The system is based on a multi-directional 3-D imager. Three dimensional object recognition has become increasingly important in factory automation. For example, automatic assembly of printed circuit (PC) boards can use a 3-D visual inspection system to detect incorrectly assembled devices. To be effective, measurement should be done from more than one angle. A visual inspection system has been developed based on a multi-directional 3-D imager and laser cross scanning. It can obtain range and intensity information of objects simultaneously. Range measurement is based on laser triangulation using a position sensitive detector. The system features: (1) Multi-directional 3-D measurement. The quad 3-D imager and X-Y laser scanner enable multi-directional 3-D measuremenL (2) High-speed. Measurement speed is 1 million pixels per second. Each pixel contains data for 256-height-level range and 256-gray-level intensity. One quad flat package with 160 leads can be measured in 4 seconds. (3) High-resolution. The inspection resolution is 25 jim in the X and Y directions and 30 pm in the Z direction. The visual inspection system uses the 32-bit MC68030 and 12 megabytes of image memory. The system was capable of detecting missing, shifting, and floating leads, and solderjoint defects.

Wide-Area, High Dynamic Range 3-D Imager

This paper describes a 3-D laser scanning imager for visual inspection of mounted devices on printed circuit boards (PCB). A 3-D imager for this application must satisfy the following requirements: (1) It must be fast enough to sense a 250 by 330 mm area in 14 seconds; (2) It must have a measurement resolution of at least 125 gm; (3) It must be capable of measuring height and light intensity simultaneously; and (4) It must have an optical dynamic range of at least 10 4. We developed a wide-area telecentric scanning optical system which meets these requirements. It uses retroreflective triangulation optics and digital signal processing hardware. Our system scans a laser beam over a 256 mm length with a resolution of 125 μm, without scanning distortion. The retroreflection triangulation optics collect light reflected from objects on a printed circuit board and focus the image on a position-sensitive detector (PSD). This system measures the profile of objects with a vertical resolution of 30 μm, within a range of 7.6 mm. The digital signal processing hardware has a dynamic range of 10 4 and obtains range data from the output signals of the PSD. Its processing speed is 1M pixels/s. This hardware enables profile measurement of objects having a wide range of light reflectance (about 3000 times), from black devices to glossy metal, with an accuracy of 0.1 mm. This 3-D imager was used in an automated inspection system for PC board-mounted devices. This system detects missing, misplaced, and incorrectly installed devices with an inspection speed of 0.1 s/device.

High-Seed 3-D Vision System Using Range And Intensity Images Covering A Wide Area

The 3-D vision system we developed uses laser scanning, and simultaneously produces range and intensity images covering a wide area. 3-D vision is indispensable in image processing for factory automation. Conventional, practical slit-light techniques using a TV camera have a limited narrow measurement area, take too long to accept input images, and cannot produce range and intensity images simultaneously. We developed a camera we call the 3-D imager and a vision system based on it. The 3-D imager uses a laser diode beam to scan the measured area and obtains range and intensity data at all points on the scan line. Range measurement is based on triangulation. The vision system, which consists of a 32-bit CPU (68020) and 12M-byte image memory, has three main features: (1) 3-D measurement covers 2048-by-3076-pixel image formed in one image input sequence. (2) Measurement is fast: The system takes 12 seconds to produce data for an entire 6-million-pixel area. (3) The system processes range and intensity data simultaneously. The 256-height-level range image is used to determine an objects shape, and the 256-gray-level intensity image to determine the surface texture, markings, and other features. When used to inspect PC boards, the system detected missing, shifted, and floating components. The inspection resolution is 125 pm in along the X and Y axes and 30 lam along the Z axis.

3-D Profile Detection Of Etched Patterns Using A Laser Scanner (3D-SCAN DETECTION) For Automatic Inspection Of Printed Circuit Boards

A new detection method named 3D-SCAN DETECTION has been developed. The method can detect three dimensional profiles of etched pattern on an inner layer of multilayer printed circuit boards (PC boards). In this system, one scanning of a laser beam allows the simultaneous detection of both top and bottom widths of an etched pattern (standard width and thickness: 100 x 35 μm) to within an accuracy of 10 pm. A prototype of 3D-SCAN DETECTION has been experimentally confirmed to have sufficient performance for the detection of such flaws as nicks in a copper pattern and poor spacing between adjacent conductors.