This paper reviews the importance of the control of non-uniform structure of sintered ceramics for its reliability improvements. The effect of coarse particles in raw powder materials on the mechanical strength of ceramics will be explained based on the experimental results, and the procedures for the reliability improvements will be discussed. It is pointed out that the binders added in the slurry also affect the mechanical strength of the final ceramics. Further analysis of the evolution mechanism of fracture origins made through the manufacturing process is crucial for better control of the reliability of mechanical strength of the sintered ceramics.