Leading Edge Processing
Copper Via Filling
Two
lines dedicated to copper filling of blind vias are
available at FIMA: the first one is a standalone line and
the second one is integrated into the plating line for panel
plating. This process is expressly required for HDI boards
where vias-inpad holes are present. The highest depth of the
dimple is guaranteed to be lower than 5 μm.
Vias Filled & Capped
and Resin Filled
The
Filled&Capped process is meant to fill blind vias or PTH
holes with resin and to plate its top and bottom. The
resulting cylinder allows soldering or electrical/mechanical
contact. This process is carried out by a machine, filling
the holes with epoxy resin. The excess resin is removed by a
plane razing machine to achieve a clean and uniform surface.
The dimple depth is in practice absent. The same machine is
also used to fill selectively PTH holes with resin after
etching.
Laser Microvias and SBU Technology
SBU
(Sequential Build Up) technology is used for HDI circuits
requiring several lamination and drilling levels: drill
sizes down to 50 μm, track and gap width down to 25 μm are
their main features. This technology is available at FIMA
and is performed by LDI machines to print inner layers,
outer layer and solder mask whilst laser drilling machine is
used to drill the blind microvias.