Thermal conductivity of copper is around 400 W/mK - aluminum is 247 W/mK, so copper is about 1.6 times as effective as aluminum would be.@Greg Jones, I’d like to know more about the copper plates and how they aid in defrosting. Is it because they conduct heat/cold well, or is there something else. If it is conduction ability, would aluminum work even better? And, do you have a source for said copper plates? Inquiring minds are interested in knowing more.