Definition

IPC-4101 is the comprehensive specification for PCB base materials (laminates and prepregs). It contains over 70 detailed specification sheets ('slash sheets') defining thermal, mechanical, and electrical properties of different material grades including FR-4, high-Tg, low-Dk/Df, and lead-free compatible materials. Specifying a slash sheet number (e.g., 'IPC-4101/126' for standard FR-4, '/129' for high-Tg) is the proper way to designate laminate requirements in your fab notes. This removes ambiguity about which material your fabricator should use.