03/06/2026
HDI micro-via formation is often implemented as a dual-wavelength process.
Getting either step wrong has direct consequences on via geometry, yield, and wall quality.
High-Density Interconnect (HDI) PCBs pack more functionality into less board space by replacing through-holes with microvias: small, precisely drilled connections between layers, typically under 150 µm in diameter. They're what makes modern compact electronics possible. Getting the drilling process right is what makes them reliable.
The dielectric removal step typically uses a CO₂ laser either at 10,6 µm or preferably in the 9.3 µm range. At this wavelength, epoxy resin and ABF dielectric materials absorb energy efficiently, enabling controlled ablation. Tighter process control, cleaner via walls, better smear profiles ahead of desmear and plating. This is, along with smaller hole diameters possible due to the smaller focal spot size, why 9.3 µm outperforms 10.6 µm for this step: better polymer absorption, less substrate heat input.
Copper is a different problem. It's highly reflective to CO₂ wavelengths, so the conformal mask opening step requires an UV nanosecond laser at 355 nm. Short pulse durations localize thermal energy, ablate the copper foil cleanly, and define the via entrance before the CO₂ laser takes over.
For OEM system builders, source stability underpins everything. Pulse-to-pulse consistency directly affects via diameter repeatability across millions of cycles. Drift in pulse energy means drift in geometry. In HDI production, that tolerance has nowhere to go.
Duralife® CO₂ laser sources are designed for exactly this kind of high-cycle microelectronics work.
Learn more at luxinar.com or contact our team to discuss your integration requirements.
