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Gold Contaminated Solder Joint Characterization for Quantifying Risks Associated with Gold Embrittlement

TECHNOLOGY AREA(S): Electronics OBJECTIVE: Develop a risk forecasting tool for quantifying the risks associated with gold-embrittled solder joints in electronic assemblies. Specifically, the model should accurately assess the likelihood of solder joint failure given specific environmental stress conditions (vibrational and thermal shock). DESCRIPTION: Circuit card assemblies (CCAs) are common in military hardware and the reliability of these CCAs is strongly dependent on the solder joints that join components and connectors to the printed circuit boards. Maximizing the reliability of solder joints is essential to maximizing the reliability of the hardware. Assembly standards for electronics, such as J-STD-001, list requirements designed to ensure solder joint reliability, including requirements designed to avoid or mitigate the risks associated with gold embrittled solder joints. The industry rule of thumb is that concentrations below 3 percent gold by weight are acceptable, but this is not a guarantee of risk mitigation as failures have been reported with joints having as low as 1.7 percent.Considerable research (references 1-4) has documented the vulnerability of solder joints to gold embrittlement. As a result, industry standards have been developed to guide CCA manufacturers and mitigate the likelihood of circuit failure. However, under many conditions, CCA?s cannot avoid some level of gold contamination in solder joints. The level of gold contamination can be quantified by non-destructive test.The purpose of this topic is to develop a model that will determine the risk of failure of gold-contaminated solder joints, for a variety of solder joint configurations, due to mechanical and thermal shock The model could be used for both: Specifying the environmental limits for the relevant military hardware; and, quantifying the likelihood of failure of the hardware given its exposure to measured/or expected mechanical and thermal conditions. Project Managers must decide if the assembly will be accepted or rejected, balancing reliability, budgeting, and scheduling impacts. PHASE I: Develop the conceptual framework for failure mode testing to evaluate the variables affecting the reliability of gold contaminated solder joints. This framework should include methods of assessing gold concentration and distribution for a variety of packaging and termination types, favoring non-destructive testing whenever possible. The framework should also consider if data generated is strictly empirical or if the data can be used for mechanistic modeling. Preference is given to mechanistic modeling as it allows for a flexible risk assessment approach. Simple physical tests should be conducted to demonstrate proof of concept. PHASE II: Execute physical testing and integrate any applicable data into mechanistic modeling with statistical analysis. Demonstrate the measurement method for identifying gold concentration and distribution in solder joints and at interfaces. Identify and quantify solder joint and CCA specific risk variables. PHASE III DUAL USE APPLICATIONS: Work with existing contractors and standards organizations to implement risk assessment parameters with preference given to a model that can be used across a wide variety of manufacturers. Measurement methods/protocols should be integrated into applicable industrial standards and best practices. KEYWORDS: Solder Joint reliability, Gold Embrittlement, Au Embrittlement POINT OF CONTACT: Aaron Pedigo, Phone: 812-854-2659, Email: aaron.pedigo@navy.mil

  • Agency: Missile Defense Agency,Department of Defense,Department of Defense
  • Program: STTR
  • Phase: Phase I
  • Release Date: August 27, 2015
  • Open Date: September 28, 2015
  • Close Date: October 28, 2015
  • URL: https://sbir.defensebusiness.org/topics
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