Nondestructive inspection via boundary scan

The increased use of very large scale integrated circuits (VLSI) and surface mount devices (SMD) by the PWB industry is making the job of the manufacturing quality control inspector more difficult. The attempts by the Joint Test Action Group (JTAG) to develop a worldwide standard for a testability bus can mean a bonus for the quality-control inspector. The author discusses some of the benefits this standard holds for test through the use of boundary scan architecture. It is shown that structured design-for-testability using the proposed JTAG/P1149.1 standard has the potential for aiding the inspector in detecting manufacturing defects. By providing a reliable, low-cost method of detecting and isolating these defects, boundary scan test can be a nondestructive inspection tool. The operating principle and architecture of boundary scan are described, and an implementation example is presented