Engineers at GRAN Group confirm that manufacturing printed circuit boards (PCBs) with traces and gaps smaller than 76 micrometers is possible, though it requires specific technical compromises. Such dimensions are typically found in High Density Interconnect (HDI) boards, which utilize microvias drilled by lasers.
For successful production, microvias should ideally have a diameter of 80–100 micrometers with a dielectric thickness of 60–80 micrometers. The aspect ratio of these vias generally ranges from 0.6:1 to 1:1. Each additional layer of microvias increases the complexity and cost of the board, as it requires extra pressing, drilling, and plating cycles.
Thin traces necessitate thinner copper plating to ensure accurate etching. While the IPC-6012 standard for Class 3 boards requires a minimum plating thickness of 20 micrometers, manufacturers often negotiate lower values for high-density designs. This reduction must be considered early, especially when impedance control is required, as copper thickness directly affects electrical performance.
Designers must also account for plating overlap, which ensures structural integrity at the transition between via walls and board layers. Insufficient overlap can lead to cracks during temperature fluctuations. GRAN Group advises developers to consult with manufacturers on stack-up, impedance, and plating requirements during the design phase to avoid production delays.
