Purpose The purpose of this study/paper is regarding analysis of electrical discontinuity in penultimate layer of a few batches of Multilayer Boards (MLB) fabricated and supplied by a vendor. The ever-increasing demand of miniaturization in launch vehicle and spacecraft electronics systems has led to the usage of multilayer printed circuit boards (PCBs) for realizing high-performance electronics circuitry. Multilayer boards (MLBs) fabricated by qualified agencies based on the customer requirement are being used in the critical launch vehicle/spacecraft systems after evaluating the preliminary test results supplied by the vendor. However, a few batches of MLBs fabricated and supplied by a particular vendor (“A”) showed a discontinuity problem in a few PCB tracks connected by soldering pads. As these MLBs are part of Flight critical systems of both launch vehicle and spacecraft, a malfunction in the board may lead to fatal errors during fight or on-orbit, thereby jeopardizing the mission. Design/methodology/approach A systematic approach was followed to have a thorough understanding of the problem, and major tests such as inspection, continuity measurement, microsection of the plated through hole (PTH) and Scanning Electron Microscopy–Energy Dispersive X-ray Analysis tests were conducted on identified test boards based on Ishikawa model. Emphasis was given for horizontal microsection, as it has got a clear edge in detecting defects at any point of PTH barrel to inner-layer copper interface. Findings Systematic testing and evaluation on specimen revealed the presence of unwanted material at the bonding area of inner-layer copper and PTH copper due to inadequate fabrication process. The un-cleaned epoxy materials present at the bonding area creates a weak bond between barrel and inner-layer copper. Electrical strength of the MLB is the strength of this link. This weaker interconnection leads to electrical discontinuity of inner-layer tracks. Originality/value MLBs are part of Flight critical systems of both Launch Vehicle and Spacecraft; a malfunction in the board may lead to fatal errors during fight or on-orbit, thereby jeopardizing the mission. Case study of an original failure observed in MLBs helped to achieve normal functioning of systems and avoided failures at later stage of mission.