Macro-micro modelling of moisture induced stresses in an ACF flip chip assembly

Yin, Chunyan, Lu, Hua, Bailey, Christopher and Chan, Y.C. (2006) Macro-micro modelling of moisture induced stresses in an ACF flip chip assembly. Soldering & Surface Mount Technology, 18 (2). pp. 27-32. ISSN 0954-0911

Abstract

Purpose – This paper discusses the use of modelling techniques to predict the reliability of an anisotropic conductive film (ACF) flip chip in a humid environment. The purpose of this modelling work is to understand the role that moisture plays in the failure of ACF flip chips.

Design/methodology/approach – A 3D macro-micro finite element modelling technique was used to determine the moisture diffusion and moisture-induced stresses inside the ACF flip chip.

Findings – The results show that the ACF layer in the flip chip can be expected to be fully saturated with moisture after 3?h at 121°C, 100%RH, 2?atm test conditions. The swelling effect of the adhesive due to this moisture absorption causes predominately tensile stress at the interface between the adhesive and the metallization, which could cause a decrease in the contact area, and therefore an increase in the contact resistance.

Originality/value – This paper introduces a macro-micro modelling technique which enables more detailed 3D modelling analysis of an ACF flip chip than previously.

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