Consideration of inhomogeneous shrinkages for LTCC-applications in panel-level processes

The aim of our study is a knowledge-based consideration of the inhomogeneous lateral shrinkage (shrinkage field) of commercial Low temperature co-fired ceramic (LTCC-) materials under free sintering conditions to improve the geometrical design fidelity and productions yield of system packages and microsystems fabricated in LTCC. Thus the phenomenological investigations of the LTCC material DuPont GT 951 under various lamination and sintering conditions are presented. Deduced from this, feasible approaches for the compensation of the inhomogeneous shrinkages are introduced. The first approach includes the consideration of the lateral inhomogeneous shrinkage already in the design process of LTCC components. This study presents a recommendation for a phenomenological modeling of the shrinkage fields for an optimized shrinkage forecast. In a further approach the sintering process is investigated. Using thermomechanical analysis methods, a chronological separation of the densification and crystallization is provided, with the aim to reduce lateral inhomogeneous shrinkages. Furthermore, sinter experiments with varied kiln furniture are presented to evaluate the effect of the friction between the LTCC panel and the sinter support. The results indicate feasible options to improve the homogeneity of the lateral shrinkage and enable the knowledge-based control of the shrinkage behavior in the design and fabrication process as well as in the material development.