Feb 16 2015

Scanned Mask Imaging Article

Laser embedding conductors within a dielectric offers numerous advantages in fabricating redistribution layers (RDLs) for chip packages when compared to conventional PCB manufacturing technologies. Ablation of features down to 2µm line width and space and vias down to 5µm diameter allows more signal routing per layer and addresses the technology gap between semiconductor and PCB manufacturing technologies. Micro-vias are made in the same process step as the circuitry, facilitating near-padless vias further increasing the routing space available per layer. 

For a given package, this reduces the layer count and conductor path length required, reducing the height profile of the package and improving signal integrity. Embedding the conductor can also improve its adhesion to the substrate and improve the co-planarity of subsequent layers in the build up. It also removes the need for the wet photochemistry required with lithographic techniques.

Two current technologies are appropriate for ablating organic dielectrics for laser embedding conductors: excimer mask projection systems and UV, diode pumped solid state (DPSS) direct write systems. The excimer systems can achieve the required ablation quality, however at a high capital cost and cost of ownership. Previously, DPSS systems had cost advantages over the excimer systems but could not achieve the required resolution and throughput.

This novel UV, DPSS, ablative mask imaging laser system provides a cost effective solution for high volume, 3D structuring of organic dielectrics. The process can achieve a comparable ablation quality to excimer laser systems with the advantage of significant cost saving and ease of maintenance in an industrial environment. 

Scanned Mask Imaging (SMI) article published in Chip Scale Review magazine.

Scanned Mask Imaging Ablative DPSS UV Laser Process for 2µm LS RDLs in high density packaging 
— Dave Myles, Research Engineer, M-Solv Ltd