Title: A robust digital image correlation technique for high-resolution characterisation of microelectronic packaging materials

Authors: Venkatakrishnan Srinivasan, Satish Radhakrishnan, Thanate Ratanawilai, Ganesh Subbarayan, Terry V. Baughn, Luu T. Nguyen

Addresses: School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA. ' Design and Technology Solutions, Intel Corporation, Hillsboro, OR – 97124, USA. ' Department of Industrial Engineering, Prince of Songkla University, Hatyai, Songkhla 90112, Thailand. ' School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA. ' Space and Airborne Systems Divisions, Raytheon Systems Corporation, Dallas, TX 75243, USA. ' Package Technology Group, National Semiconductor Corporation Santa Clara, CA 95052, USA

Abstract: In this study, we demonstrate a robust Digital Image Correlation (DIC) technique and describe the methods implemented in the DIC code for characterising microelectronic packaging materials. We show how sample preparation may be entirely eliminated by using the natural speckle inherent in specular (rough) surfaces with the help of a robust correlation measure implemented in the code. We use DIC to characterise both time-independent and time-dependent material properties at high spatial and displacement resolution. We measure the Coefficient of Thermal Expansion (CTE) of common metals such as copper and aluminium followed by characterisation of 19 Printed Circuit Board (PCB) coupons. We characterise the CTE of microscale Alumina (Al2O3) specimen using its natural speckle. We calculate the strain and therefore the modulus during mechanical testing of copper, epoxies as well as fibre-reinforced composite materials. Finally, we characterise the time dependent behaviour of a microfibre-reinforced composite (RT/Duroid) at high temperature.

Keywords: DIC; digital image correlation; electronics packaging; speckle correlation; materials characterisation; microelectronic packaging materials; coefficient of thermal expansion; CTE; copper; aluminium; printed circuit boards; PCB coupons; fibre reinforced composites.

DOI: 10.1504/IJMPT.2009.022409

International Journal of Materials and Product Technology, 2009 Vol.34 No.1/2, pp.139 - 157

Published online: 04 Jan 2009 *

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