==== AlVsFe ====
== Aluminum or Iron Substrates? ==

Version 5 thinsats weigh 2.5 grams per 0.025m², or 0.1kg/m².   So far, we've been considering aluminum substrates.  What about iron?

Assume thinsat substrates are 80% of the weight;  0.08kg/m².  

||    ||  Z || AtW || kg/m³|| Ω-nm || W/m-K || ||  Z/A || th μm || mΩ/□ ||  K/W ||
|| Al || 13 ||  27 || 2700 ||   27 || 237   || ||  6.3 ||    30 ||  0.9 ||  140 ||
|| Fe || 26 ||  56 || 7870 ||   96 ||  80   || || 12.1 ||    10 ||  9.6 || 1250 ||

Iron?  No.  Although the Z²/AtW Rutherford scattering ratio is double, it is 10x more resistive electrically and thermally.