New Low-Cost, High Performance Approach to EMI Shielding at the Circuit Board Level

High speed electronics suffer from an increased vulnerability regarding electromagnetic interference. The problem is even more acerbated by an environment of extreme electromagnetic pollution. Wide band shielding against electromagnetic interference is therefore crucial if reliability of electronic devices is to be maintained. A conventional and very effective solution to this problem is to put a shielding gasket over electronic offenders and victims alike. The shield is easily installed but suffers from being cumbersome and environmentally exposed; a damaged shield basically does not work. An alternative, direct approach is to shield potential electromagnetic emitters and receivers at the circuit board level, thereby reducing space, material, cost., and weight. An additional advantage is the. Increased integrity owing to the environmental seal. Although, shielding on the circuit board level can he provided by some conductive inks, shielding effectiveness is currently limited by their comparatively low conductivity and reliability. If shielding performance is to match that of shielding gaskets, both areas need to be improved considerably. This proposal offers a novel conductive ink approach based on transient-liquid-phase sintering. It addresses in particular the need for electromagnetic shielding on the board level with a highly conductive and stable ink. We anticipate development of a new transient-liquid-phase sintering ink for electromagnetic shielding in electronic packaging. Markets include aerospace, automotive and electronic devices in general. US market size for electromagnetic shielding materials is expected to increase to $270 million in 1997.