SMTA International Conference Proceedings


Author: Ana L. Campuzano-Contreras
Company: BAE Systems
Date Published: 9/24/2006   Conference: SMTA International

Abstract: The Joint Council on Aging Aircraft (JCAA) and the Joint Group on Pollution Prevention (JG-PP) Lead-Free Solder project began in 2001 to address the need for comprehensive test data on the reliability of lead-free (Pb-free) solders. The objective of the project was to compare relative reliability of Pb-free and baseline tin-lead (SnPb) solder joints under different environmental testing conditions. This paper documents test results of the “Rework” test vehicles. Previous published papers by the project participants have described assembly and test details in more depth than is covered in this paper [1-9].

The “Rework” test vehicles were designed to assess the impact of using Pb-free components and processes to repair circuit card assemblies designed for assembly with eutectic processes. Eight components, two of each of the following; BGA-225, TQFP-144, DIP-20 and TSOP-50 were selected. The Pb-free solders used were either tin-silver-copper (SAC), tin-silver-copper-bismuth (SACB) or tin-copper (SnCu). Combined environments, vibration, mechanical shock, thermal shock, and thermal cycle (-55°C to +125°C) testing were used to assess the reliability of the joints. Electrical reliability better than or equal to SnPb controls was the acceptance criteria. In summary, rework showed mixed results based on component type and test environments. Additional studies, modeling, and qualifications will be required to establish long term reliability confidence.

Key words: Pb-free, aerospace, military, SnPb, RoHS

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