Abstract
Temperature distribution and flow pattern of natural convection around IC packages on the vertical circuit board in silicone oil were made visiable with the liquid crystal particle suspension method. Natural convection around IC packages were affected by the array of IC packages on the vertical board. Thermal boundary laye and thermal plume around IC packages were made clearly observation. The difference in temperature of the surface of IC packages and the mean value of oil decreased with increasing the horizontal distance of the upper and under IC packages.
