Definition of foreign material

1. 1 : an adherent particle that is not parent material of the component. Adherence means that the particle cannot be removed by an air or nitrogen blast at 20 psi. [SEMI G58-94] 2 : in flat panel display substrates, an opaque or partially melted particle of refractory or batch material embedded in glass. Its size is usually determined by the size of the distorted area. [SEMI D9-94] .