Beyond which boundary could lighter, volatile materials condense into solid ice grains necessary for giant planets?

Past the frost line

The development of the gas and ice giants in the outer solar system depended critically on the presence of solid material beyond a certain distance from the Sun. This critical boundary is termed the frost line. Before this line, temperatures were too high, meaning volatiles like water, methane, and ammonia remained gaseous. Past the frost line, temperatures dropped sufficiently (around 150 K) for these substances to condense into solid ice grains. The availability of these much more abundant solid materials allowed cores in the outer nebula to grow massive enough, quickly enough, to gravitationally capture the vast envelopes of remaining hydrogen and helium gas before the solar wind dispersed that gas.