Adhesion measurement for electronic packaging applications using double cantilever beam method

Multilayers and interfaces are ubiquitous in microelectronics devices, inte rconnect and packaging structures. As the interface integrity becomes the m ajor concern of performance, yield, and reliability, the need to evaluate t he fracture and delamination behavior of various interfaces increases. This work focused on quantifying interfacial adhesion performance of a typical electronics packaging structure, flip-chip-on-organic-substrate. A series o f experiments and analyzes were conducted to investigate the adhesion and f racture behaviors of the underfill/silicon and underfill/organic substrate interfaces. The experimental techniques for the interfacial fracture experi ments were developed to produce the double-cantilever-beam (DCB) specimens and to establish a reproducible testing protocol. To extract the interfacia l fracture energies, a closed-form solution was developed based on a beam-o n-elastic-foundation model. A two-dimensional elastoplastic finite element analysis (FEA) model was also implemented to examine effects of mode-mixity ; thermal/residual stresses, and underfill plasticity The techniques allow for reproducible determination of underfill/printed circuit board (PCB) and underfill/silicon chip interfacial adhesion strength. The developed techni ques are also readily applicable to evaluate interfacial adhesion performan ce for many other similar electronic packaging systems. This provides capab ilities in optimizing materials selections and process conditions to improv e interfacial adhesion performance. Additionally, the interfacial fracture energy measured with high accuracy can provide a basis for realistic modeli ng of thermo-mechanical reliability of electronic components.