New high-density multilayer technology on PCB

Demand has recently increased for very high-density packaging substrates fo r high-pin-count area array chips, Our new high-density multilayer technolo gy on printed circuit board (PCB), named deposited substrate on laminate (D SOL) satisfies this demand, An important feature of the DSOL is dielectric fabrication, which uses a new photosensitive material; an aromatic fluorene unit bonded epoxy acrylate resin, The fluorene based resin has interesting properties such as good electrical properties, low curing temperature (160 degrees C) for a heat-resistant resin (glass transition temperature, T-g = 230 degrees C), low coefficient of the thermal expansion (40 ppm), and exc ellent via hole resolution, Very fine and high-aspect-ratio (>1.0) via hole s mere formed through exactly the same process steps as those used for a co nventional photosensitive epoxy resin; baking, exposure, and development wi th an aqueous alkaline solution. Another important feature is the technolog y, that patterns fine-pitch Cu conductors using a semi-additive process wit h a sputtering method. The DSOL made 40 mu m very fine pitch Cu conductors on large laminates (330 mm x 400 mm) possible, because this process was com posed of flash wet etching of only 0.3 mu m thick sputtered thin-films. We have successfully developed a high-density packaging substrate for high-pin -count (4000 pins) area array application specific integrated circuit (ASIC ) chips.