Plasma junction

From Memory Alpha, the free Star Trek reference

A plasma junction was a component on the electro-plasma system on 22nd century Klingon Birds-of-Prey. It was a major flaw in the ship's design, as it was exposed along the nape of the ship's neck and primary hull, vulnerable to enemy fire.

In 2154, a stolen Bird of Prey under the control of renegade augments had its entire power grid disabled by a single phase cannon shot by the Enterprise. (ENT: "The Augments")