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• Fixed position of punching tools: The design of advanced post-etch punch machines fea- tures a fixed position for the punching tools. This mechanical rigidity and absence of moving tool parts contribute significantly to the exceptional positional accuracy of the punched holes and consequently the align- ment of inner layers. By eliminating variables associated with tool movement or indexing, the system ensures highly repeatable and reliable hole placement, which is critical for precise layer-to-layer registration (Figure 5). These sophisticated capabilities allow manu- facturers to achieve outstanding results, even on complicated boards, such as those with high layer counts, fine-pitch features, or mixed material stack- ups. The ability to precisely control and compen- sate for minute shifts translates into superior final product quality, as evidenced by cross-sections demonstrating minimal shifts between copper lay- ers (Figure 6). Summary The journey to multilayer PCBs begins with pre- cise inner layer alignment. While each method— pin-lam, mass-lam with two machines, and mass- lam with one automated machine—remains viable, the optimal choice hinges on a careful evaluation of several critical factors: • Accuracy requirements • Capability to measure inner layers before lay-up • Required productivity levels • Pre- and post-processing needs • Panel sizes • Predictability • Maintenance requirements • Compatibility with different materials Ultimately, the best inner layer alignment method is a strategic choice for each manufac- turer, tailored to their production goals, technol- ogy roadmap, and board designs. This stage is a critical control point that directly affects overall factory efficiency, waste reduction, and final prod- uct quality. PCB007 Kurt Palmer is president of Schmoll America. To read past columns, click here. D R I V I N G I N N OVAT I O N 42 PCB007 MAGAZINE I JULY 2025 ▼ F i g u re 6 : C ro s s - s e ct i o n w i t h m e a s u re m e nt ove r l ay, s h ow i n g m i n i m a l s h i f t b et we e n to p a n d b ot to m c o p p e r l aye rs . ( S o u rc e : G o r i l l a C i rc u i t ) ▼ F i g u re 5 : F i xe d to o l i n g .