Semiconductor package having improved adhesion and solderability

A leadframe comprising:

• a base metal structure having first and second surfaces;
• said first surface oxidized to form an oxide layer of said base metal adhesive to polymeric materials;
• and
• said a metal layer covering said second surface having affinity to reflow metals.

A semiconductor device comprising:

• a leadframe of a base metal with a first and second surface, a chip mount pad and a plurality of lead segments, each segment having a first end near said mount pad and a second end remote from said mount pad;
• a first metal layer, adhesive to polymeric materials, adherent to said first surface;
• and said second surface covered by a second metal layer for affinity to reflow metals, said second metal layer having a different composition from said first metal layer;
• a semiconductor chip attached to said mount pad;
• bonding wires interconnecting said chip and said first ends of said lead segments;
• and
• polymeric encapsulation material covering said chip, said bonding wires and said first ends of said lead segments.

A semiconductor device comprising:

• a leadframe of a base metal with a first and second surface, a chip mount pad and a plurality of lead segments, each segment having a first end near said mount pad and a second end remote from said mount pad;
• said first surface oxidized to form an oxide layer of said base metal adhesive to polymeric materials with selective areas covered by a silver layer;
• and said second surface covered by a metal layer for affinity to reflow metals;
• a semiconductor chip attached to said mount pad;
• bonding wires interconnecting said chip and said first ends of said lead segments;
• and
• polymeric encapsulation material covering said chip, said bonding wires and said first ends of said lead segments.

A method for fabricating a leadframe comprising the steps of:

• providing a base metal structure having first and second surfaces;
• preparing said first surface metallurgically so that it becomes adhesive to polymeric materials;
• and
• preparing said second surface metallurgically so that so that it becomes affine to reflow metals.