A composition for a bond ply, and a circuit subassembly that comprises such bond ply, are disclosed. The circuit subassembly can have a UL-94 rating of V-0. The composition of the bond ply layer comprises 25 to 45 volume percent of liquid resin; 10 to 40 weight percent of a bromine-containing or phosphorus-containing aromatic compound having a peak melting point of at least about 260° C.; and 5 to 35 volume percent inorganic filler.