IPC 4101E covers the requirements for base materials that are referred to as laminate or prepreg. These are to be used primarily for rigid and multilayer printed boards for electrical and electronic circuits. This document contains 64 individual specification sheets that can be searched using keywords. These keywords allow the document's user to find materials of a similar nature, but with specific differing properties that fine-tune their laminate and/or prepreg selection needs. The E revision includes six specification sheets which reflect the expanded offerings for current commercially available laminates and prepregs with improved or additional properties that are one or more of the following: low-halogen content, high-thermal performance, high speed/high frequency performance or thermally conductivity.