Core · Weapon · Rules

This uses the same rules as a Field Weapon, except that the attacking Unit is destroyed, and Units within its Squad can be damaged by it. If a Unit with a Self-Destruct Weapon is destroyed while not Embarked, roll a D6. On a 4+, the Unit must immediately attack with the Weapon before being removed, even if it could not normally attack.

Source: Dropzone Commander Rulebook 3.02 · 3.02 · p. 50 · weapon-special-rules