T8 - Lead-free solder performance: Characterization, failure prediction, and industrial application

Rainer Dudek (Fraunhofer IZM, Chemnitz),

Rainer Dudek (Fraunhofer IZM, Chemnitz), Steffen Wiese (TU Dresden), and Sven Rzepka (Qimonda Dresden GmbH & Co OHG)

Reliability issues have become a major concern in the process of lead-free solder materials introduction into industrial practice, particularly in demanding applications. To achieve competitive product developments and manufacturing processes, it is essential to apply effective methods for reliability assessment, e.g. based on Finite Element Analysis (FEA). Successful implementation of these methods also in packaging applications using lead-free solder materials require a profound knowledge in lead-free solder bulk and joint materials characteristics, mechanical properties, and fatigue life prediction as well as dynamic loading evaluation strategies, which are provided in the course. Reference will be made to conventional SnPb, 1st generation and 2nd generation SAC solders.

This Workshop will provide updated knowledge on lead-free solder materials and reliability performance (A Design For Reliability (DFR) methodology employing solder materials testing, modeling, non-linear finite element analysis and fatigue life prediction will be presented along side experimental reliability test results. Finite element analysis (FEA) modeling of board level solder joint reliability assessments for several lead-free and tin-lead materials will be presented. FEA modeling for related reliability issues in packaging will be additionally discussed.

Design, quality and reliability professionals who are responsible for quality and reliability implementing lead-free electronic packaging and electronic assemblies.

Survey – Introduction

• Risk Assessment
  (What are the typical risks for manufacturability and reliability of electronic components and modules?)
• FEA DFR strategies for BGA modules
  (How can FEA help optimizing the design of BGA modules for extended 2nd level lifetime?)
• Evaluation of mechanical tests
  (How comparable are the results of mechanical tests done in industry today?)

Material Models

• Overview on electronic polymeric and metallic materials
• Accuracy of Material Models
  (Difficulties and pitfalls in setting up an appropriate material model)
• Basics of Deformation of Metals
  (Dislocation glide, dislocation climb, flux of vacancies, grain boundary sliding – Why metal physics understanding helps to set up constitutive models for FEM simulation?)
• Scaling Effects
  (Why small structures and bulk material behave differently?
  Experimental ways to characterize small structure behaviour)

Failure

• Life prediction models - Strain-based relations (accumulated creep strain), Energy-based relations (average viscoplastic strain energy dissipated).
• FEA modeling and simulation of Thermal Cycling Tests
• Parametric studies on the effects of design parameters on the fatigue life of FCOB with and without underfills, CSPs and BGAs
• Comparison between simulation results and experimental results.