Also Leo, if you design a mine using Mine Warheads 1, a ship with Organic or Cristalline or Scattering Armors could skip your minefields without take damage... For this, most the players go for Mine Warheads 2 very fast.
Erm... I believe that exploit was patched out a while ago. 2-3 patches ago, IIRC. Mine damage now accumulates, and each mine/warhead no longer has to destroy components entirely.