One of the main challenges facing the PCB industry is the need to reduce board footprint by creating vias with the minimum diameter and maximum depth (high aspect ratio) that will connect all layers of the printed circuit board. Mechanical drilling is not applicable for this purpose, as small diameter drill bits break easily and cannot penetrate multiple layers. The only way to achieve the desired aspect ratio is to vertically stack laser drills (micro-vias). To ensure that the drills are aligned with each other and are located at the correct depth (Z-Axis), the drills must be filled before the next pressing cycle.
Existing pre-filled epoxy-ceramic & Cu capped filling methods are not suitable for miniaturized PCBs in which the boards’ thickness is very small in size. Manufacturing a PCB with aligned laser drills requires CU fill (electroplated) of the micro-vias to assure, among others, no dimples are created which might result in reduced performance. This process allows optimal electrical conductivity between all stack-up layers.
PCB Technologies recently purchased a new CU fill (electroplated) machine (manufactured by #LSR), which was specially designed to meet this challenge. The machine is equipped with several agitation and spray systems to ensure uniform copper coating of the micro-vias.
This machine allows the filling of laser micro-vias with small diameters and aspect ratios as high as 1.1