Circuit substrate and method for forming bumps on the circuit substrate

A circuit substrate for use in manufacturing integrated circuit devices by the strip-support method in connection with semiconductor elements having conductive pads, said circuit substrate comprising:

• base means formed of insulating material;
• circuit means supported on the base means for mechanically and electrically coupling to the conductive pads on a semiconductor element, including a plurality of finger leads with bumps proximate the ends of each finger lead for mechanically and electrically coupling to one of the conductive pads, and
• plating means for increasing the roughness of the connection surface of the bumps to bond the bumps and conductive pads firmly by breaking any oxide film formed on the conductive pads of the IC chip;
• whereby a stronger more reliable connection between the circuit means and semiconductor element conductive pad is achieved.

A method for forming bumps on the conductive layer mounted on base means formed of insulating material of a circuit substrate for attachment of the circuit substrate to conductive pads of a semiconductor element, comprising:

• coating a front and a back surface of the conductive layer with photo-resists;
• patterning the photo-resists on both surfaces of the conductive layer by simultaneous exposure and development;
• half-etching both surfaces of the conductive layer;
• coating one of the surfaces of the conductive layer with a protective resist;
• etching the other surface of the conductive layer;
• and
• removing the photo-resists and the protective resist;
• whereby a bump is formed on the first surface.