A Systematic Evaluation of Factors Influencing TAB Inner Lead Reliability

Reliability evaluations for new electronic components and assemblies regularly require extensive test cycles that are both time consuming and costly. Objectives of such test batteries are to identify failure mechanisms and the relationship between these mechanisms and product design or processing features. Optimisation of these critical factors or process steps results in optimised reliability. Statistically designed experiments can facilitate the optimisation process by minimising the amount of testing needed to identify factors affecting reliability, and by providing insight into how these factors can be specified to ensure optimum product design. Designed experimentation was utilised in this study to look at product design and process factors affecting the reliability of inner leads for tape automated bonding (TAB) components. Four factors are considered: outer lead compliancy; chip immobilisation; downset; and tape stiffness and rigidity. Experimental details and results are presented which assess the relative importance of these factors in determining ultimate inner lead reliability, and also provide guidance for final product design considerations.