PCB Testing and Failure Analysis: Methods and Techniques
One of the pillars of contemporary electronics is the printed circuit board. Without contemporary high-density circuit board technology, it would be impossible to build even relatively simple consumer electronics with the sheer number of components and interconnects needed to join them. Clearly, this increased level of complexity creates new difficulties for failure analysis; for example, locating an open trace may take hours of arduous work looking over board layouts and innumerable microsurgeries on the board before the faulty node is eventually isolated. Even after the failure has been identified through comprehensive printed circuit board testing, an analyst still faces challenges since they must figure out how to locate the hidden problem.
Thankfully, a variety of tools have been created that can significantly help an analyst get to the heart of a PCB. By allowing an analyst to image the entire board in search of hot areas brought on by leakage rather than cutting and probing individual nodes on the board, tools like thermal imaging can substantially simplify the printed circuit board testing process. Time domain reflectometry is an additional helpful technique for pinpointing open-circuit issues on a printed circuit board and requires little setup.
The analyst’s next challenging task is to identify the flaw that will be photographed when printed circuit board testing and isolation are complete. The general strategy is to mount the board for parallel deprocessing in a manner akin to that of mounting an integrated circuit for delayering. Using this method, an analyst can gradually remove each layer of the board while tracking the winding path traveled by a signal of interest until the flaw is discovered. Conversely, an analyst may decide to cross-section the device and search for flaws that span multiple layers as opposed to those that are restricted to a single plane.
The work of printed circuit board testing becomes more difficult as PCBs are denser (many modern consumer gadgets have boards that compress ten or more conductive layers into a region that is less than one millimeter thick). It takes patience, the right equipment, and experience gained from years of exposure to cutting-edge PCB technology to find flaws in these mazes of copper and epoxy.
Video 01: PCB Failure Analysis | FT-IR Microscopy | Electronics
