Affiliation:
1. Department of Mechanical Engineering, Chang Gung University , Kweishan, Taoyuan 33302 , Taiwan
Abstract
Abstract
The ball-on-ring test (BoR) is one of the standard tests for biaxial bending, suggested in ASTM F394-78. This test has been applied to determine the biaxial bending strength of silicon dies to avoid the die edge effect of the three-point bending tests. However, from the literature, when the relatively thin silicon dies are tested, this test suffers from a contact-nonlinearity effect, due to a maximum applied stress moving away from the loading pin center before the specimen failure, and thus results in overestimated maximum stress calculated by the theoretical linear solution. This study aims to investigate this mechanical issue experimentally, theoretically and numerically by taking into account the specimen material anisotropy and thickness effects on the maximum stresses and deflections, and then propose new correction factor equations to the theoretical linear solutions, based on the numerical fitting results of the geometric nonlinear finite element solutions. Those correction factor equations proposed in this study are material-property independent, but specimen thickness dependent, which can be estimated by an interpolation function. It has been proved that the BoR test using the conventional theory associated with the proposed correction factor equations can successfully determine the bending strength of the thin silicon dies on untreated surfaces, which mostly fails in the contact-nonlinear region.
Funder
National Science and Technology Council
Publisher
Oxford University Press (OUP)
Subject
Applied Mathematics,Mechanical Engineering,Condensed Matter Physics
Reference28 articles.
1. Ultra-thin Chip Technology and Applications
2. Thin silicon wafer processing and strength characterization;Gambino,2013
3. Ultra-thin chips for high-performance flexible electronics;Gupta;npj Flex Electron,2018
4. Materials and mechanics issues in flip-chip organic packaging;Wu,1996
5. Investigation of thermo-mechanical behaviors of flip chip BGA in IC packaging;Tsai,2004