Antimatter Warhead

Antimatter Warhead is one of the strongest, most destructive warheads available to Mankind. It's exact production progress is extremely hard to achieve and requires a very advanced technology. It is also immensely costly, making whole salvoes composed of them rather... hard to justify from economical standpoint.
What's more, the Antimatter Warhead is essentially detonated in the factory, during the very end of its construction proccess. Since that moment the explosion is stalled by magnets that keep the particle and antiparticle away from each other. Every malfunction ends up with detonation that is strong enough to annihilate even the strongest ship, especially when it happens without a prior warning and within the ship itself.
Such explosions are, obviously, extremely rare. Despite this, the bad PR the antimatter warheads got because of them sticks, and makes many captains rather nervous when they got them onboard.