Methods and apparatus for an interposer with dams used in packaging dies are disclosed. An interposer may comprise a metal layer above a substrate. A plurality of dams may be formed above the metal layer around each corner of the metal layer. Dams may be formed on both sides of the interposer substrate. A dam surrounds an area where connectors such as solder balls may be located to connect to other packages. A non-conductive dam may be formed above the dam. An underfill may be formed under the package connected to the connector, above the metal layer, and contained within the area surrounded by the dams at the corner, so that the connectors are well protected by the underfill. Such dams may be further formed on a printed circuit board as well.