Toru Ishida’s research while affiliated with Osaka Gas Co., Ltd. and other places

A new chip scale package (CSP) using an organic laminated substrate called μCSP was developed, which was fabricated using ALIVH substrate as a interposer and stud-bump-bonding (SBB) flip-chip technology. The ALIVH substrate is a multilayered organic substrate with inner via holes in any layer. The newly developed CSP-L using ALIVH substrate realized a miniaturization of its package size to the same as a CSP using a ceramic substrate (CSP-C). In order to perform the SBB flip-chip bonding onto the ALIVH substrate, an excellent coplanarity of the substrate surface was required. The required coplanarity was obtained using a fixture during the SBB flip-chip bonding process. The first-level packaging reliability and the second-level packaging reliability onto ALIVH mother board were evaluated. The resulting reliabilities were good enough to apply to practical use

This paper presents ceramic multi-layer substrates for mobile communication using alumina-glass composite ceramics and co-fired copper conductors. Electrical characteristics in GHz frequencies of the substrate, copper conductor, transmission line, via hole and coupling between the striplines were evaluated. The results showed that the ceramic multi-layer substrate had good electrical characteristics enough for GHz-band applications. Using the ceramic multi-layer substrates, one can drastically reduce the size of RF circuit boards for mobile communication equipment.

We applied a flip-chip-bonding technique to GHz-band SAW filters. The SAW filters mounted by the stud-bump-bonding (SBB) technique which is a kind of flip-chip-bonding technique showed almost the same frequency characteristics as those mounted by the conventional wire-bonding technique at 1.5 GHz. The SAW filter configuration, fabrication process using the SBB, and its electrical characteristics are described and discussed. The SBB technique has a lot of potential to reduce the size and weight even above GHz frequencies.

A new process for manufacturing a co-firable copper-multilayered ceramic substrate has been developed. In contrast with the copper paste used in the conventional process for manufacturing copper-multilayered ceramic substrates, this new method uses copper oxide paste as the precursor for the conductive material. After the organic binder is burnt out in the air, the copper oxide paste is reduced and sintered in this process. This fabrication method permits complete removal of the organic binder contained in the dielectric layers, which was difficult to achieve by the conventional method. This process makes it possible to produce copper-multilayered ceramic substrates having excellent insulation characteristics. Furthermore, this fabrication method realizes the co-firing of copper-multilayered ceramic substrates at low temperature, thus contributing to the simplification of the process.