aaEvery module can be upgrade-able except Mk2 & Mk3. Unlock at level 16. Use Chip and Credit to upgrade, use Unit and Chance Multiply to increase success rate to upgrade. Some upgrade stats need higher level module level. which require Overclock Chip and Credit to upgrade module level.
You can upgrade every module to level 5. Inside every module level, it is required to fully upgrade all stat wise upgrade which is called sub-upgrade, then to be able to upgrade the module level. Every module level could unlock different stat to be upgrade-able.
Upgrade success chance will be decrease by each sub upgrade success by:
100% 90% 85% 80% 75% 65% 55% 45% 35% 25% 15% 10% 9% 8%
Energy Consumption -3.75%
Turn Power +1.5%
Mine Disruption Chance
Rocket Disruption Chance
Torpedo Disruption Chance