The following section contains information from a previous version of StarCraft II which is no longer valid.
In early builds the tech lab researched upgrades and special abilities for some units, but these upgrades were transferred to merc compound, armory and fusion core. Currently the tech lab is responsible to research armor and weapon upgrades for the units.
The tech lab was mocked up as a science facility add-on but later repurposed when Blizzard decided that buildings didn't get specific add-ons, they could either get a reactor or tech lab.
In December 2012, the ability to research Seeker Missiles for the Raven was removed; the ability is now an automatic one for the Raven.
The raven deploys a seeker missile that hovers for five seconds before launching at the target. Deals 100 splash damage against both ground and air unit, in a radius of 2. +35 shield damage is dealt when used in Co-op Missions. The splash damage can damage friendly units. The missile moves at a speed of 2.953.
The missile can be avoided if the targeted unit avoids it long enough. The targeted unit is visually indicated by a red aura.
Caduceus Reactor at tech lab, which reduces healing cost. The enhanced healing beam will change color. A fusion core is required for the upgrade. The upgrade was later reverted to the Wings of Liberty version via the January 9, 2013 balance update.
During development of Legacy of the Void, the tech lab was used to research an upgrade for cyclones that allowsed them to gain the ability to attack air units. This upgrade requiresd the presence of the fusion core.