Novel boron nitride agglomerated powders are provided having controlled density and fracture strength features. In addition methods for producing same are provided. One method calls for providing a feedstock powder including boron nitride agglomerates, and heat treating the feedstock powder to form a heat treated boron nitride agglomerated powder. In one embodiment the feedstock powder has a controlled crystal size. In another, the feedstock powder is derived from a bulk source. Devices, such as microelectronic devices and printed circuit boards, which include boron nitride agglomerates with controlled fracture strength features are also disclosed.