Accession Number : ADP005188

Title :   Laser Inspection Calibration Baseline for Thermal Signature Analysis,

Corporate Author : LITTON SYSTEMS INC GRANTS PASS OR GUIDANCE AND CONTROL SYSTEMS DIV

Personal Author(s) : Ensign,Douglas H.

Report Date : FEB 1987

Pagination or Media Count : 26

Abstract : Thermal signature analysis method for the interpretation of Vanzetti laser inspection sensor data, when applied to solder joint process analysis, will be superior to existing statistical threshold methods. A thorough understanding of the laser inspection process and parameters is required along with accurate system calibration. This paper will provide a general definition of the laser inspection process and its equipment, a brief history of laser inspection and details of the system baseline development program. The system baseline development program was designed to establish a repeatable system baseline for system effects on sensor output from system component fluctuations, ambient temperature fluctuations, and target irregularities. In addition, a system transfer function was produced to derive optimum thermal signature amplitudes. A system signal-to-noise threshold was established. As a result of this program, a calibration method was developed holding signature repeatability to 2%. As a result of this calibration method and subsequent thermal signature analysis, success has been measured in the detection of small subsurface solder voids.

Descriptors :   *PRINTED CIRCUITS, *INSPECTION, *LASER APPLICATIONS, SOLDERED JOINTS, THERMAL RADIATION, INFRARED SIGNATURES, SIGNAL TO NOISE RATIO, TRANSFER FUNCTIONS, NEODYMIUM LASERS

Subject Categories : Mfg & Industrial Eng & Control of Product Sys
      Optical Detection and Detectors
      Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE