Leadless packaging process using a conductive substrate

Abstract

Improved methods of packaging integrated circuits in leadless packages are disclosed. A conductive substrate sheet is initially patterned to form troughs that define a multiplicity of device areas. Each device area includes a plurality of contact landings (and preferably a die attach pad) that are formed in substrate sheet by patterning. The patterning can be done using a variety of conventional techniques including etching. A multiplicity of dice are then attached to the substrate sheet and bond pads on the dice are electrically connected to associated contact landings using conventional techniques such as wire bonding. One or more caps are then molded over the device areas to encapsulate the dice and bonding wires and to fill the troughs. After the caps have been formed, excess portions of the substrate sheet (e.g. portions below the troughs) are removed to electrically isolate the contact landings thereby forming electrically isolated independent contacts in a molded package. In the resulting arrangement, the molding material serves to hold the contacts in place as well as to electrically isolate the independent contacts. The excess substrate material can be removed using a variety of techniques including mechanical grinding and chemical etching and/or a combination of the two. In the described arrangement, the “excess” substrate material serves to prevent the formation of flash below the contacts during the molding operation. The “excess” substrate material also supports the die attach pad and the contacts during both wire bonding and the die attach process.