Temperature-dependent adhesion measurements of die attach materials to moulding compounds and lead frame surfaces enabling robust package designs

Stress tests are utilised to accelerate failure mechanisms in semiconductor packages during reliability and robustness assessments. One potential failure mechanism is the loss of adhesion at an interface, leading to the failure mode called delamination. A possible location of such a delamination is between moulding compound and die attach material (bleed-out or fillet). Often an extension of this delamination to the die pad can be observed. A common belief is that the interface opens due to low adhesion of moulding compound to the die attach material. A new, simple test vehicle design was implemented to characterise the adhesion of die attach materials to moulding compounds and substrates. The test vehicle design of the Advanced Button Shear Test was extended to incorporate a layer of die attach material. This new design can be used to conduct Advanced Button Shear Test experiments for a quick selection of promising material combinations. Studying time-dependent effects using creep tests is another option for the characterisation of adhesion, as well as the determination of critical adhesion energies.