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APRIL 2025 I PCB007 MAGAZINE 81 Laser Alignment Laser machines follow a similar registration approach when alignment holes are avail- able. However, in cases where no alignment holes exist, a specialized process is required: 1. e laser skives the top copper layer, also removing a small portion of the dielectric. 2. e CCD camera of the laser machine then recognizes inner-layer fiducials for align- ment and proceeds with the main part pro- gram drilling. Process engineers must carefully adjust skiv- ing parameters to ensure the laser does not penetrate deeper than the required reference layer (Figure 6). Outer Layer Exposure Alignment Outer layers are typically aligned using X-ray-drilled holes or holes created during main drilling. However, when PCBs contain both mechanical and laser-drilled holes, an addi- tional approach can be used. Combo targets are a mechanically-drilled fiducial combined with multiple laser-drilled fiducials to create a Figure 5: Two-station drilling machine with independent tables/stations and CCDs at each station. Figure 6: Fiducial on inner layer visible after skiving of the top copper layer by laser.