Circuit-board structure

Abstract

Abstract PURPOSE:To enhance bonding strength by a method wherein the surface of a bump at the tip part of a finger lead has a specific surface roughness and an irregularity ratio of the number of maximum protruding parts to the number of minimum protruding parts at the protruding part is set to 1.5 or lower. CONSTITUTION:In a circuit-board structure of a tape-carrier system by a board provided with bumps, surfaces 7 of bumps 6 installed at tip parts of finger leads 4 have uneven parts whose surface roughness is 1 to 5mum; an irregularity ratio of the number of maximum protruding parts to the number of minimum protruding parts at the protruding parts is set to 1.5 or lower. As a result, the number of protruding parts at one bump 6 is several pieces or higher and several hundred pieces or lower; an IC chip 9 and aluminum pads 11 can be bonded stably. Thereby, a bonding strength can be enhanced sufficiently; an irregularity in the bonding strength with reference to any other bump part is reduced; it is possible to reduce irregularity in bonding quality at each finger.

Inventors

• 👤 Hisanori Maruyama
• 👤 久則 丸山

Bibliographic Details