chip to the substrate are within the scope of the present disclosure fig2 also shows an underfill 50 which may be filled between chip 30 and first substrate 20 a second set of solder balls 60 may be secured to contact pads not shown on the lower surface of first substrate 20 the combination of the first substrate 20 and the second set of solder balls 60 on the lower surface thereof are commonly known as and referred to as a ball grid array second set of solder balls 60 may also be secured to contact pads not shown on a second substrate 70 which may be a printed wire board also sometimes called a printed circuit board or may be a multilayer module known to those skilled in the art the fcbga package 10 may also include a heat spreader 80 and one or more stiffeners 90 for preventing excess warpage of the fcbga package 10 heat spreader 80 is mounted on top of chip 30 and counter balances the forces exerted by the thermal expansion mismatches between at least the chip 30 and the first substrate 20 the heat spreader 80 and the stiffeners 90 may be formed integrally or employed as discrete elements and may substantially comprise materials having relatively high coefficients of thermal expansion in one embodiment the heat spreader 80 comprises copper tungsten aluminum silicon carbide aluminum stainless steel copper nickel and or nickel plated copper.