Its cause of the damage of ignition coil

The ignition coil itself cause of damage of ignition coil have? 1 and ignition coil their own reasons, internal primary enameled wire paint scratches easily breakdown short circuit, or is secondary coil slot insulation breakdown cause a short-circuit. 2, design flaws, internal high and low voltage coil distance less than the breakdown. 3, material defects, coil internal insulation material after high temperature failure of the breakdown. 4, process defect, assembly or potting process have impurities mixed with, or not completely clean, decreased local insulation breakdown.