STRUCTURE OF CONDUCTIVE BUMP ON WIRING BOARD

摘要

PROBLEM TO BE SOLVED: To narrow a pitch of a wiring pattern and thereby form a high density wiring pattern by forming insulating projections at specified places on an insulating base and forming conductive bumps with these projections and parts of leads which cover the surfaces of the projections. SOLUTION: A wiring board 1 has a wiring pattern formed from leads 3 which are extended, being airtightly adhered to the surface of an insulating base 2. One end each of these leads 3 is gathered in an area where an IC 4 is mounted to form a conductive bump 3a. As for a forming method for these conductive bumps 3a, local areas of the insulating base 2 are allowed to rise from the surface to form insulating projections 6 and the surfaces of these projections 6 are covered by parts of the leads 3, in other words, the leads 3 are so laid as to cover the projections 6 and conductive bumps 3a are formed at the ends of the leads 3. Each of the bumps 3a has such a structure that a cavity 12 formed when part of the lead 3 is shaped into a mountain may be filled with the projection made by allowing a local area of the insulating base 2 to rise from the surface and be backed up by it.