Reliability Improvements by the Creation of Intermetallic Connections
The possibilities to combine small and large passive components, and new devices for active components with an increase in reliability is discussed.
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Authored By:
Jorg Trodler, Dipl.-Ing.
Heraeus Deutschland GmbH&Co.KG
Hanau, Germany
Dr. Ing. Habil Heinz Wohlrabe
Technical University Dresden
Dresden, Germany
Summary
Especially for the SMT new trends like miniaturization 0201, 01005, 0201 (metrics) for passive components, as well as new devices for actives like LGA or QFN, it requires a lot of investigation for researching, developing, questioning about application, product/component mix, and finally about reliability. One major challenge is the combination of small, medium and large components in one production step. For example, large components need more solder paste, based on a thicker stencil than small components.
Several studies have shown, that properties for reliability at a temperature cycle e.g. -40/+125 prolonged its lifetime by increasing an intermetallic phase (IMP) between substrates and component finishes (e.g. Papers Trodler SMTAi 2012-14). This paper will show and discuss the possibilities by application to combine small and large passive components, and new devices for active components with an increase in reliability, especially for automotive/industry requirements by an IMP formation.
Conclusions
Based on the positive results for reliability and the challenge for more complex boards without using different types of paste (powder size) and stencils, more assembly steps, a project has been started for harmonizing and searching the limits with solder paste and one stencil thickness as well as different openings in the stencil. With those results, the process flow can be described and additional reliability test could be follow to proof an increasing for bigger component as well.
Initially Published in the SMTA Proceedings
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