A heat sink of solid state phase change material for a heat sensitive downhole tool component. The heat sink may be of a polyhydric alcohol based or other suitable material which is capable of undergoing a phase change from one solid form to another. That is, the phase change material need not undergo a phase change into a liquid form in order to absorb well heat and provide substantial protection to the heat sensitive downhole tool component. Thus, cost effectiveness, manufacturability and performance may all be enhanced which may be particularly advantageous where the component is of a single application use variety.