WLCSP Intermediate Structure for Thinner High-Density Packaging

The patent introduces an intermediate structure with redistribution layers (RDLs) and conductive vias as a mediator between the interposer substrate and the final package. This intermediate structure enables thinner solder joints by redistributing electrical connections across multiple layers, allowing the package thickness to be reduced while maintaining integration density through the use of multiple conductive pathways in a compact vertical arrangement.

The patent transitions from a two-dimensional planar interconnection approach to a three-dimensional vertical stacking approach by implementing multiple redistribution layers (RDL1, RDL2, etc.) stacked vertically with conductive vias connecting them. This dimensional change allows electrical connections to be routed through the thickness direction, enabling reduced package thickness while maintaining high integration density through vertical space utilization.

The patent segments the interconnection structure into multiple functional layers including interposer substrate, multiple redistribution layers (RDL1, RDL2, RDL3), conductive vias, and capping layer. Each layer performs a specific function: the interposer provides mechanical support, RDLs provide electrical redistribution, vias provide vertical interconnection, and the capping layer provides protection. This segmentation allows standard manufacturing processes to be applied to each layer independently, reducing overall manufacturing complexity while achieving compact package size.

The intermediate structure with redistribution layers serves multiple functions simultaneously: it provides electrical redistribution to accommodate reduced pitch, acts as a mechanical support structure, enables vertical interconnection through vias, and allows for thermal management. This multi-functionality reduces the need for additional specialized components, thereby controlling manufacturing complexity while achieving miniaturization.