Micro chevron (MC) test (critical energy release rate)
The wafer bond characterization is based on different methods and tests. Wafer bonds are commonly characterized by three important encapsulation parameters: bond strength, hermeticity of encapsulation and bonding induced stress.
The bond strength can be evaluated using double cantilever beam or chevron respectively micro-chevron tests. The chevron test is used to determine the fracture toughness and the surface fracture energy of brittle construction materials. The micro chevron (MC) test is a modification of the chevron test using a specimen of defined and reproducible size and shape. The test allows the determination of the critical energy release rate and the critical fracture toughness . The MC test is applied with special specimen stamp glued onto the non-bonded edge of the processed structures. The specimen is loaded in a tensile tester and the load is applied perpendicular to the bonded area. When the load equals the maximum bearable conditions, a crack is initiated at the tip of the chevron notch. The energy release rate is related to the fracture toughness.
|GIC||The energy release rate (Pa*(m1/2)2)|
|KIC||The fracture toughness (Pa*m1/2)|
|E||Modulus of elasticity ( Young's modulus) (Pa)|
|ν||Poisson's ratio (dimensionless)|