Criminal entrepreneur Justin Hammer provided several of his armor-using villain customers with technology that had been stolen from Anthony Stark's top secret designs. When Iron Man discovered so, he started a personal quest to disable these designs. Stark designed the Negator Pack, that destroyed these designs when in contact with any of these armors, and built several units. Having identified the opponents he was to track, Stark donned his own Iron Man armor and went after them.
Iron Man first used the Negator Pack in the Stilt-Man's armor and then in the Controller's armor. Iron Man then fought the three Raiders and disabled their armors, one by one, using three Negators Pack. (Brendon Doyle willingly gave his Mauler armor to Iron Man).
Mistakenly believing that superhero Stingray was using this stolen technology, Iron Man fought Stingray and used a Negator Pack, only to discover that the Pack was not working because Stingray's armor was not a Stark design - an action that caused a public relation problem for Iron Man. Continuing with his plan, Iron Man then used Negator Packs to crash the Beetle's armor, and then he opposed Nick Fury's SHIELD to use Negator Packs in the Mandroid Armors, which were being used by elite SHIELD agents - meaning that they were not criminals, but agents of the law. Iron Man then used Negator Packs on the armors used by the Guardsmen, heroic watchmen of the prison Vault (Maximum Security Installation for the Incarceration of Superhuman Criminals). This action confronted Iron Man with his old friend the Captain (previously Captain America). It also confronted Iron Man to the US government, who branded Iron Man a fugitive. As Iron Man was leaving the Packs attached to armors of his victims, the government took hold of them and, by analyzing the one in Stingray, they developed a way to shield an armor from the Pack's effect. The government built the Firepower Armor with this Negator Pack immunity, specifically to capture Iron Man.
Iron Man then travelled to USSR to confront the Titanium Man and the Crimson Dynamo. Iron Man used his Stealth armor and two Negator Packs for this. Although he managed to disable the Dynamo's armor, the Titanium Man smashed Iron Man's last Negator Pack before it could be used. Iron Man then fought the Titanium Man and apparently killed him.
The government then sent the Firepower armor, to be used by military man Jack Taggert, against Iron Man. During their duel, Iron Man tried to use a Negator Pack in the Firepower armor, but it was useless, and Taggert explained him way.
After this, Stark decided to include a self-destruct chip with codes that only he would know, in all his further top-secret armor designs.
When connected to any armor using Anthony Stark's technology, the Negator Pack fused and melted the circuits related to Stark's designs, rendering them useless. The armor-wearing person's security during the process was not guaranteed.
Each Negator Pack can be used only once: After one use, the item is useless. It won't work if the armor does not include Stark's circuits, or if the armor is specifically protected against it (although the armor's designer needs access to a Negator Pack to protect an armor like this).