Evaluation of interfacial fracture strength in micro-components with different free-edge shape

Abstract

The strength against interfacial fracture nucleation from the free-edge of micro-scale bimaterial cantilevers consisting of silicon (Si) and copper (Cu) components is evaluated by using specimens with different free-edge shape. The fracture strength of Type A (90°/90° edge) specimens represented by the near-edge stress normal to the interface (σθθ) is significantly scattered. On the other hand, the fracture strength of Type B (135°/135° edge) specimens represented by the stress intensity factor of σθθ shows very good agreement. This indicates that the introduction of a sharp wedge at the free-edge is an effective measure for the evaluation of fracture strength that is unique to the interface. Such characteristics are also found to be unaltered by the plasticity of Cu component. The advantage of Type B specimen is then applied to the evaluation of the effect of gaseous environment on the fracture strength. There is no eminent reduction of strength value in hydrogen (H2)-containing gas, indicating that Si/Cu interface is relatively resistant against hydrogen embrittlement.

Keywords

• micro-components
• silicon
• copper
• interface
• free-edge
• fracture nucleation
• strength
• fracture mechanics
• hydrogen embrittlement