A Novel Inorganic Substrate by Three Dimensionally Stacked Glass Core Technology

2.5D and 2.1D technologies aim at improving wiring density and packaging density. However, both 2.5D and 2.1D technologies present coefficient of thermal expansion (CTE) mismatch issues and an increase in the assembly process. To overcome such limitations, we developed a glass package stacked glass core which uses the conductive paste as interlayer connection vias. We fabricated and then studied a multilayer glass package substrate. The daisy chain of such multilayer glass package substrate passed through a reflow test for five times. During the reflow process, the warpage of the multilayer glass package substrate turns to be lower than that of an organic package substrate. In addition, the CTE of the multilayer glass package substrate is approximately 3 ppm/°C, as in silicon. The bending strain of the multilayer glass package substrate becomes stronger as the number of layers increase and its internal stress is lower than the glass interposer. We believe that the proposed multilayer glass package substrate will guarantee high-density wiring, with high reliability and high packaging density, and that it can be optimally used in practical applications instead of 2.5D and 2.1D technology.