For a general introduction to cause mapping, see root-cause-analysis.php.
This cause map deals with a manufacturing problem. Too many integrated circuit
chips were failing. Inspections showed that the metal lines were too narrow. The
problem or primary effect is shown on the left in red. Color is not necessary in
cause mapping, but it is helpful to highlight the main problem. In this
cause map the evidence boxes are shown in purple to distinguish them from the
You read this chart from left to right and add the words "was caused
by" at each line. For example, "Metal was over etched" was caused
by "Temperature of etch incorrect" or "Time in etch
incorrect" or "Etch mixed incorrectly" or some combination of
By checking all the possible causes, it was found that the oven which baked the
photoresist was malfunctioning and that caused the metal lines to be too narrow
and the IC chip to fail.