High density PWB (printed wiring board) with microvia technology is required for implementation of high density and high I/O area array packages (AAP).  COTS (commercial off-the-shelf) AAP packaging technologies in high reliability versions with 1.27 mm pitch are now being considered for use in a number of NASA systems including the Space Shuttle and Mars Rovers.  NASA functional system designs are requiring ever more denser AAP packages and board features, making board microvia technology very attractive for effectively routing a large number of package inputs/outputs.  However, reliability of fine feature microvias, including via in pads, is unknown for Space Applications.  Understanding the process and QA indicators for reliability are important for low risk insertion of these newly available packages and PWBs.  This report documents the body of knowledge (BOK) on microvia board technology based on a literature search of various technologies and their relevance to NASA missions and high reliability applications.