The influence of microscopic roughness on macroscopic adhesion properties of polymer-metal interfaces

O. Sluis, van der, S.P.M. Noijen, P.H.M. Timmermans, J-B Bouquet

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

Abstract

Fracture of polymer-metal interfaces is one of the main failure modes occurring in micro-electronic components. At the macroscopic scale interface adhesion originates from contributions at different length-scales: (1) chemical interactions such as primary bonds and physical interactions such as secondary bonds at the nano-scale; (2) micro-scale phenomena due to surface roughness such as crack kinking into the surrounding bulk material, increase in bonding area and plastic dissipation [1,2]. For polymer-metal interfaces it is known that the main contribution to macroscopic adhesion can be attributed to crack kinking at the micro-scale: the interface crack deflects into the polymer which is driven by the (irregular) geometry of the roughness profile [3]. In order to predict the effect of roughness on adhesion it is therefore imperative to take into account the competition between adhesive and cohesive failure in the analysis of the underlying interfacial microstructure. A semi-analytical approach, based on the pioneering work by He and Hutchinson [4], is developed in which the competition between adhesive and cohesive cracking is analyzed by means of the theoretical relation between interface and kinking stress intensity factors. The parameters that define this relation, the solution coefficients, are quantified by numerical simulations. Accordingly, the crack kinking location and kinking angle into the softer polymer is readily calculated. Next, a numerical approach is applied in which adhesive and cohesive cracking processes are analyzed by transient numerical simulations employing cohesive zone elements. Clearly, the kinking angle and position are direct results of these simulations. To properly deal with the occurrence of limit points during these simulations caused by the brittleness of the interface and bulk materials, a local arc-length solver is employed which is based on the weighted sub-plane method [5]. In this formulation, the damage in the active cohesive zone elements controls the load in the solution procedure. The results from both approaches will be compared. Finally, experimental analysis is used to study the occurring cracking phenomena in selected bi-layer samples and to validate the results of the semi-analytical and transient numerical approaches.
Original languageEnglish
Title of host publicationProceedings of the 2nd International Conference on Computational Modeling of Fracture and Failure of Materials and Structures (CFRAC2011), 6-8 June 2011, Barcelona, Spain
EditorsJ Oliver, M Jirasek, O Allix, N Moës
Place of PublicationBarcelona, Spain
PublisherInternational Center for Numerical Methods in Engineering (CIMNE)
Pages221-
ISBN (Print)978-84-87867-66-8
Publication statusPublished - 2011
Event2nd International Conference on Computational Modeling of Fracture and Failure of Materials and Structures (CFRAC 2011), June 6-8, 2011, Barcelona, Spain - Barcelona, Spain
Duration: 6 Jun 20118 Jun 2011

Conference

Conference2nd International Conference on Computational Modeling of Fracture and Failure of Materials and Structures (CFRAC 2011), June 6-8, 2011, Barcelona, Spain
Abbreviated titleCFRAC 2011
CountrySpain
CityBarcelona
Period6/06/118/06/11
Other

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