Experimental Observation of Downward Flame Spread over Printed Circuit Board:

Influence of Gap Distance between Side Surface of Sample and Sample Holder on Flame Spread Rate and Extinction Limit

Abstract

The effect of the sample holding method on the flame spread phenomena of printed circuit boards was investigated. To realize the two-dimensional flame spread front over the printed circuit board, we provided the air gap between the side edge of the sample and sample holder wall. The air gap can reduce the heat loss from the sample to the holder, however edge propagation started to appear when the size of the air gap increased excessively. To find an optimal size of the air gap, flame front shape, flame spread rate, and limiting oxygen concentration were measured by changing the size of the air gap and those results are reported in the presetnation.