Seiichi Nakatani

Co-fireable copper multilayered ceramic substrates

The authors discuss the manufacture of co-fireable copper multilayered ceramic substrates utilizing green-tape technology. The substrates were manufactured using an oxidation-reduction reaction, employing CuO paste as an inner-layer conductor. Two types of substrate materials were developed, a crystallizable glass that has good flexural strength, and an amorphous glass which has a low dielectric constant. The burnout process is performed in air. The reduction process is carried out in a nitrogen atmosphere containing 10% hydrogen in which copper oxide is reduced into copper, and sintering is performed in the nitrogen. Low impedance, migration resistance, and low cost have resulted from the use of a Cu conductor.<<ETX>>

Development Of Zero X-y Shrinkage Sintered Ceramic Substrate

Studies of multilayered ceramic substrate are made briskly ,which makes it possible to design wiring patterns high densely and to mount bare IC chips. The multilayered cbramic substrate is expected for effectiveness for high functional, downsizing and confidential devices. In order to realize high density ceramic Multi-Chip-Module (MCM), multilayered ceramic substrate is required to satisfy demands for fine patterning, small packaging and low cost, Especially, sintering shrinkage of a substrate should be. controlled for fine patteming. Generally, the ceramic substrate undergoes its shrinkage of 10 to 15% and the shrinkage error is *OS%, so the substrate is not suitable for mounting bare IC chips. On considering of such problem, zero X-Y shrinkage sintered ceramic substrate (ZSS) has been developed by the conventional green sheet method, which arranges substrate green sheets between two no-shrinkage sheets, horizontal shrinkage during sintering is prevented to 0.18, and the shrinkage error i s f 0.05%. In this paper, we will report a material, process for prohibiting the horizontal shrinkage and properties of ZSS. .

A new composite substrate with high thermal conductivity for power modules

Recently, it has become more important to take the thermal dispersion of circuit boards into account. We have developed a new composite substrate with high thermal conductivity (HTC-CS) which is suitable for power modules. The main points of development of the substrate are: (1) newly developed composite materials with high thermal conductivity; (2) use of the lead frame (L/F) as a conductive layer; (3) use of thermally conductive sheets (TCSs) and realization of a simple procedure. Alumina and epoxy resin were mixed to make a slurry and were made into sheets by the doctor blade method. The sheet (TCS) was flexible while the resin was not hardened. The TCS was laid on the L/F and heated under pressure. The TCS moved into the gaps in the L/F patterns and the surface became flat; simultaneously, the resin in the TCS hardened to produce a rigid substrate. The substrate thermal conductivity was above 5 W/mK. The substrate was applied to intelligent power modules (IPM). These IPMs showed good reliability. In addition, it is simple to insert a shield layer in the substrate using the TCS procedure, and the substrate has high noise stability.