The variation in Anand model parameters – How does that affect the bond's response? A comparative study considering sintered Ag bonds

Finite element analysis (FEA) is a widely used technique for simulating the thermally induced mechanical behavior of die bonding materials in electronics. The Anand unified viscoplasticity model is commonly employed to simulate the mechanical responses of such interconnections. This model comprises nine parameters, the individual effects of which are not fully understood in the literature. This paper aims to investigate the impact of each Anand parameter on the mechanical response of sintered silver (Ag) bonds through extensive finite element simulations. Various Anand models for sintered Ag, sourced from literature, are utilized to create a systematic study matrix for each parameter. These material coefficients are then incorporated into thermal and thermomechanical simulations to induce inelastic deformations in the sintered Ag bonds. The bonding layer response is analyzed in terms of stress-strain relationships, inelastic strains, and inelastic strain energy density. The results indicated that certain Anand parameters could cause the bond response to shift towards brittle behavior, while others could result in a more ductile behavior. Using statistical factorial analysis, it is found that the significance of each parameter varied greatly, from negligible to highly significant. The findings of this study are valuable for understanding the behavior of various bonds configurations and their expected thermal fatigue performance based on their Anand creep constants. Additionally, this paper lays the groundwork for understanding the meaning of Anand constants and their influence on the mechanical response of any bond material which is not discussed in literature yet.