Micro Via and Flex Circuit Panels Tech Note
Micro Vias – Generally described as a via or hole through one or more layers of a flexible circuit board made of laminations of alternating insulating and conducting layers of material. These materials are often copper sheet (1/2 oz typically) and an epoxy/fiberglass blend in thin sheets (.001-.002” thick). The laser drilling tool will create a via from the top layer down to a copper catch pad below which will be plated to form an electrical connection between conducting layers.
The drilling, and subsequent plating works best when the diameter of the via is equal to or greater than the depth of the via (a 1:1 ratio is ideal). Accu-Tech regularly generates vias in the range of .003” to .008” (.075-.100mm) with capability to produce smaller and larger sizes.
Our systems can align to pre-etched openings in the top layer and remove the dielectric down to the next layer, or create openings in a solid copper top layer aligned to your lower layer registration fiducials and then remove the dielectric. Supplying pre-etched openings in the top layer may be more cost effective – depending on your etching capabilities. Pre-etched boards can have a quicker turn around time.