Study of the multilayer PCBCTEs by moire interferometry

Microelectronics packaging has been developing rapidly due to the demands for faster, lighter and smaller products. Printed circuit boards (PCBs) provide mechanical support and electrical interconnection for electronic devices. Many types of composite PCBs have been developed to meet various needs. Recent trends in reliability analysis of PCBs have involved development of the structural integrity models for predicting lifetime under thermal environmental exposure; however the theoretical models need verification by the experiment. The objective of the current work is the development of an optical system and testing procedure for evaluation of the thermal deformation of PCBs in the wide temperature range. Due to the special requirements of the specimen and test condition, the existing technologies and setups were updated and modified. The discussions on optical methods, thermal loading chambers, and image data processing are presented. The proposed technique and specially designed test bench were employed successfully to measure the thermal deformations of PCB in the -40degreesC to +160degreesC temperature range. The video-based moire interferometry was used for generating, capturing and analysis of the fringe patterns. The obtained information yields the needed coefficients of thermal expansion (CTE) for tested PCBs. (C) 2004 Elsevier Ltd. All rights reserved.