This specification covers the requirements for base materials (laminate and prepreg) for rigid or multilayer printed boards for electrical and electronic circuits. This document contains more than 50 specification sheets and now uses search terms to allow the user to find similar groups of materials from these specification sheets. This standard provides the user with additional information and data on printed circuit board materials that are better able to withstand the newer assembly operations employing higher thermal exposures, including those that use lead free solders. Amendment 1 to Revision B inserts corrected information on Conductive Anodic Filament (CAF) growth into six Specification Sheets and into this document's body. Additionally, Amendment 1 provides corrections for both Permittivity and Loss Tangent in Specification Sheets 126 and 129. Amendment 2 to Revision B provides seven additional changes: a) Corrects the Z-axis CTE for Specification Sheet 129 to 3.5%; b) In section 3.12.1.4, reference to IPC-9691, a CAF guideline is included for clarity; c) In section 3.10.1.6, a statement is added that recognizes that different test methods yield different results and the specific test method shall be stipulated; d) Dielectric loss tangent values corrected for Specification Sheets 31, 32 and 33; e) Specification Sheet 58 has the minimum Peel Strength requirements increased for all three conditions for standard profile foil; f) In section 3.10.1.12, the test specimens are more closely defined and controlled; and g) More clearly defines what is meant by 20-20 visual acuity. Supersedes IPC-4101B with Amendment 1. 110 pages. Released March 2007.