Abstract: A semiconductor device is provided with copper traces for connecting active elements to an external device, and insulating layers of black oxide (cupric oxide) are formed on the traces. The active elements may be, for example, conductors on the active surface of a semiconductor die. The external device may be, for example, a memory device or an input/output device. The invention eliminates the need for a resist solder mask. The black oxide prevents solder from adhering to the traces except where desired. The black oxide layers preferably do not cover the entire surfaces of the semiconductor device. The oxide layers grow only on the surfaces of the copper traces. Consequently, the dimensions of the finished device may be minimized. Black oxide may also be used to promote adhesion between the die and the substrate.

Abstract: According to the present invention, for a multi-layer plastic package having bonding pads at multiple levels, a plurality of electrically independent side wall conductive layers can be provided by forming side wall conductive layer on the side wall of an opening in each insulating layer. In particular, when the insulating layer forms a multi-layer structure, side wall conductive layers are formed on each of the individual side walls of the multi insulating layers, and a pre-impregnated layer is inserted between each two insulation layers, so that a plurality of electrically independent side wall conductive layers can be provided. Even for an insulating layer having a single layer structure, side wall conductive layers are formed so as to be electrically separated from each other, so that a plurality of side wall conductive layers can be provided.