Authored By:
Brook Sandy-Smith
Indium Corporation
Clinton, NY, USA
Summary
There are many facets to PCB reliability and also a variety of strategies to ensure the most reliable assemblies. Bottom termination components, such as BGAs, CSPs, MLFs, QFNs, and D-Paks, pose additional challenges to some aspects of reliability. Three aspects will be addressed: electro-chemical reliability, assembly defects, and alloy reliability.
For each aspect, unique challenges for BTCs, solutions, and strategies for optimization will be discussed. In order to maintain the highest quality of PCB assembly, all three must be considered and addressed at different phases of design and production.
Conclusions
These components are already being used in various electronics assemblies and can be reliably and repeatably assembled. These proven approaches can be used alone or in combination to achieve continuous improvement. The strategies behind these studies define parameters in which to consider areas of process optimization: board design (pad patterning, via placement), printing process (best practices, aperture design), placement, reflow profiling, cleaning, and reliability. Using materials such as specially designed solder pastes and flux-coated solid solder preforms also solve these challenges.
Research is on-going for several of these approaches. The full results associated with the preliminary examples presented here will be published at IPC ESTC in May, 2013, and SMTA International in October,
Initially Published in the SMTA Proceedings
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