On the mechanic reliability of structured glasses as substrates in advanced packaging applications

Glasses are widely considered as substrates for advanced packaging, chiplet integration and heterogeneous integration. Applications range from high performance computing, automotive applications, radar packages to telecommunication in 5G/6G antenna in package concepts. The reason to use glass is manifold: Geometric rigidity, stiffness, smooth surfaces, superior dielectric properties, adjustable thermal expansion and the availability in wafer and large panel formats play an important role to consider glass as a substrate material in packaging. However, glasses are brittle materials and the mechanic stability of a brittle material is dominated by the defect statistics on its surfaces in combination with regions of tensile stresses. Structuring glasses with cut-outs and through glass vias (TGV's) creates a large amount of additional surface [1]. Such comparison between finite element calculations of stress distributions and experimentally derived failure statistics of the same structures. From this design rules can are derived to obtain mechanically stable, structured glass substrates as a core for advanced packaging and heterogeneous integration.