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Mechanical Reliability - Updated Results from a Spherical Bend Test Program

Presenter: John McMahon
Company: Celestica
Date Published: 5/8/2013

Description: Overview
The increased temperatures associated with Lead free processes have introduced significant new challenges for PWB suppliers. Cost competitive, Lead free process compatible laminates are typically phenolic cured epoxy based composites, filled with ceramic particles or micro-clays. While Tg values are no longer the sole indicator of thermal resistance, high complexity assembly is now almost completely associated with 170-180 C Tg materials. These changes which are aimed at improving the materials resistance to thermal excursions and maintaining electrical integrity through primary attach and rework operations have produced harder resin systems that we now understand to have lower fracture toughness. Celestica has been conducting an ongoing testing program to assess Lead free compatible materials and area array packages against the currently accepted levels of process strain. The latest phases of this work have been designed to extend our understanding of component construction dependencies, to begin investigations into some other package types and to compare more materials. This webinar outlines the theory and practice of the test vehicle design, the assembly and test method used to generate data and then discusses selected test results and failure modes determined by physical failure analysis.

1) Introduction
2) DOE Methods & Design

  • Material processing
  • Test configuration and set up
    3)DOE Results
    4)Translating Results into Risk
    5)Additional Contributing Factors

    Who Should Attend
    Technologists, Engineers and managers who are interested in or responsible for: process control, process yield and product field performance.

    About The Presenter
    John McMahon holds a degree in Metallurgical Engineering with a specialty in mechanical testing and fracture mechanics from the Technical University of Nova Scotia. He joined Celestica in 1996 and has held a variety of engineering positions at Celestica including qualification of all manufacturing facilities for Lead free assembly. He is currently responsible for the "High Complexity Initiative", A group of development and qualification projects targeted directly at the retirement of the ROHS "Lead in Solder" exemption and the conversion of Enterprise Computing and Telecomm products to Lead free assembly. He has been actively involved in research on BGA failure mechanisms, solder joint reliability, deformation of electronic assemblies and strain measurement since 1999 and is the author of several papers on these topics.

  • Key Words: 

    Spherical Bend Test, lead free, materials

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