An excessive ESD transient can damage the downstream circuitry. The pictures shown here illustrate the effect of an ESD pulse. On the left, the ESD pulse has punched a hole down through the layers of the IC, thereby short circuiting the various silicon layers making the performance of the IC ineffective. On the right, the ESD pulse has damaged a trace on the IC. In this case, the trace has not opened, but will cause intermittent operation. Excessive ESD transients can also cause open traces and definite signal failure on data lines.