Structuring redistribution layers down to 2 micron line spacing with laser direct ablation

We show how laser direct ablation can be used to yield μ-vias below 10μm diameter and line spacing feature down to 2μm. The laser direct ablation technique is applicable to photosensitive materials as well as non-photosensitive materials since the underlying principle of the laser ablation is common to all polymers. We show how by controlling the laser fluence (energy per unit area) and number of laser pulses, we can respectively control the wall angle as well as the feature depth. Eliminating costly photolithography chemistry makes laser direct ablation a cost effective approach to structure redistribution layers (RDL).