A seal, fill head, and system are provided. The seal is adapted to cooperate with a fill head that is configured to place conductive bonding material into cavities on a mold. The seal comprises a first outer wall that is configured to abut a first adjacent wall of a support groove in a fill head. A second outer wall is configured to abut a second adjacent wall of a support groove in a fill head. An outer horizontal wall is situated between the first outer wall and the second outer wall. The outer horizontal wall comprises at least a first portion that is configured to abut an upper portion of the support groove. A convex bottom portion extends from the first and second outer walls. The convex bottom portion is configured to cooperate with a top surface of a mold.