Analyses and solutions to unsafe testing states from boundary scan testing

IEEE 1149.1 standard provides an effective approach to testing circuit boards with physical limited access. Unsafe testing states may be occurred during the duration of boundary scan testing when both design-for-testing on circuit board and testing script are not perfect. Case studies on unsafe testing states occurred in the duration of boundary scan testing is provided based on our testing work performed over the recent years, reasons are analysed and solutions are proposed.