Fail mode evaluation using light microscopes and SEM techniques Description of Technique Wire bond and die attach strengths on ICs and other electronic devices can be evaluated using the Dage Microtester-22. Wire bonds are evaluated using the wire pull method in either destructive or nondestructive mode. In addition to tabular and statistical presentation of the numerical and qualitative results, light microscope and SEM photographs of wire bonds and die fails are available. To enhance the validity of the test results, care should be taken not to chemically or mechanically attack or undermine the bonds to be evaluated.
Facilities are available to evaluate and open intact devices for wire bond and die shear testing.
For new or special packages, test samples must be provided for development of an appropriate decapsulating technique. The fail mode is manually recorded by the operator. The failing force is recorded on paper tape, along with pertinent statistics which summarize the number of bond pulls. If a failure occurs before reaching the preset value, the reading at failure is recorded. Otherwise, the preset value is recorded.