A method of forming a semiconductor package. Implementations include forming on a die backside an intermediate metal layer having multiple sublayers, each including a metal selected from the group consisting of titanium, nickel, copper, silver, and combinations thereof. A tin layer is deposited onto the intermediate metal layer and is then reflowed with a silver layer of a substrate to form an intermetallic layer having a melting temperature above 260 degrees Celsius and including an intermetallic consisting of silver and tin and/or an intermetallic consisting of copper and tin. Another method of forming a semiconductor package includes forming a bump on each of a plurality of exposed pads of a top side of a die, each exposed pad surrounded by a passivation layer, each bump including an intermediate metal layer as described above and a tin layer coupled to the intermediate metal layer is reflowed to form an intermetallic layer.

The present application relates to an electronic document module comprising a medium having a so-called internal face provided with at least two contact interfaces with an antenna, each of the contact interfaces with the antenna of the internal face of the medium being configured to be in contact with a connection pad of an antenna of an electronic document body, and with a chip comprising at least one I/O port, and one of the two contact interfaces with the antenna of the internal face of the medium being connected to the I/O port of the chip. The application also relates to an electronic document comprising such a module and a method for checking a connection between the module and a corresponding antenna.