Bond Integrity
Mechanical assessment determines the structural integrity of individual solder bumps against lateral forces applied at a controlled height. The ball shear test measures the maximum load required to detach a solder ball from its bond pad. Operators use a precision tool to apply force at a specific distance above the substrate surface.
This height remains constant to ensure data reproducibility across different samples.
Rupture Classification
Bond quality depends on where the fracture occurs during the application of force. In a successful ball shear test, the solder itself should deform or fracture while the intermetallic layer remains intact. Failures occurring at the pad interface or within the laminate suggest weak adhesion or brittle intermetallic growth.
Brittle fractures at the interface often indicate excessive thermal exposure or contaminated plating chemistry. Ductile failures within the solder bulk confirm that the bond interface is stronger than the alloy itself. Each fracture path provides specific data regarding the assembly process or surface finish quality.
Instrument Velocity
Instrument movement occurs at a speed that influences the recorded peak force and fracture appearance. Low speeds allow for plastic deformation of the solder alloy. High speeds emphasize brittle characteristics within the bond structure.
Standardized settings ensure that results from different laboratories are comparable and reliable for process validation.
