High-performance flip-chip BGA based on multi-layer thin-film packaging technology

The greater number of I/O pads and higher chip operational frequencies of recently-developed high-performance ASIC chips have created a strong demandfor high-density and high-performance flip-chip BGAs (Ball Grid Arrays). Our new concept flip-chip BGA, based on MLTF (Multi-Layer Thin-Film) packaging technology, satisfies these demands. The concept of MLTF packaging is to leave only a high-density, high-performance, multi-layer thin-film by mounting an LSI chip on a metal-base multi-layer thin-film substrate and removing the base metal plate. The MLTF packaging has the advantages of 1) good registration accuracy, which makes higher-density and finer-pitch pattering possible, 2) a through-hole-less structure that is highly suitable for high-speed and high-frequency applications, 3) excellent flip-chip mounting reliability, which makes higher-pin-count and finer-pitch area array flip-chip interconnection possible, 4) excellent reliability, supported by use of high Tg (Glass Transition Temperature) resin such as polyimides, and 5) a cost-effective design achieved as a result of fewer layers fabricated with fine-pitch patterning. We successfully developed a high-density flip-chip BGA prototype based on our MLTF packaging technology. The prototype comprises an LSI chip connected to approximately 2,500 bonding pads arranged in 240 ion pitch area array, and 1296 110 pads for BGA. The prototype flip-chip BGA excellent long-term reliability was demonstrated through a series of tests conducted on it.