Motoyo Wajima

Fine line circuit manufacturing technology with electroless copper plating

Two types of additive processes for fine circuit pattern manufacturing technology using electroless copper plating have been developed. The processes offer high dimensional accuracy. Technical aspects of the additive processes, materials for the fabrication of additive circuits, and the performance of these circuits are reported here.<<ETX>>

A New Fully Additive Fabrication Process for Printed Wiring Boards

A new fully additive manufacturing process for printed wiring boards is presented, and the performance of boards fabricated by this technology is evaluated. The attainment of satisfactory performance levels using this additive process is achieved by the development of a substrate and an accompanying metallization process having suitable properties. The new process uses commercially available unclad laminates as base materials and includes the following steps: 1) coating and curing of adhesive on the base laminate, 2) drilling of holes, 3) roughening and catalyzing of the adhesive surface, 4) printing negative circuit patterns by screen printing, and 5) formation of conductive circuits by full-build electroless copper plating. Reliability of the through hole interconnection was examined by thermal shock cycle tests. The peel strength between plated copper foils and substrate was measured before and after various heat treatments by soldering. The fully additive process makes it possible to fabricate reliable high-performance printed wiring boards with fewer processing steps than conventional subtractive processes.

Low dielectric material for multilayer printed wiring boards

A low-dielectric material for high-speed digital multilayer printed wiring boards (MPBs), maleimide-styryl (MS) resin, was developed by reacting styryl prepolymer with ether-type bismaleimide. Since MS resin has good processabilities, prepregs and copper clad laminates can be made under conventional conditions used for epoxy and polyimide laminates. The laminates are characterized by their excellent heat-resistant properties, which are almost the same as those of polyimide laminates, and low moisture absorption, which is the same as that of epoxy laminates. The laminates comprising the MS resin and several reinforcements have low dielectric constants, ranging from 3.3 to 3.7. Using the laminates, a high-density MPB with 62 printed wiring layers was made.<<ETX>>

High density multilayer printed circuit board for HITAC M-800

Investigations were performed on ways to raise signal transmission velocity of printed circuit boards (PCBs). A low dielectric laminate (dielectric constant=3.7) for the PCBs, which has almost the same thermal stability and flame retardancy as a polyimide one, was produced by a maleimide-styryl (MS) resin synthesis based on a molecular design technique in combination with optimum reinforcement. A high aspect ratio fine pattern formation process was established by pattern copper plating. Signal linewidth was 70 mu m and its thickness was 65 mu m. A high aspect ratio fine through-hole formation process was derived by optimization of the drilling conditions. Using all these technologies, a high density, multilayer printed circuit board (MPB) with 46 layers and 730 mm by 534 mm in size was developed. This high-performance MPB was applied to the HITAC M-880, the newest and largest mainframe computer manufactured by Hitachi. >

Characterization of brominated poly(4-hydroxystyrene) derivatives containing unsaturated groups

Abstract Brominated poly(4-hydroxystyrene) (HS) derivatives containing unsaturated groups such as alkenyl or alkenoyl were investigated with infrared and 1H nuclear magnetic resonance spectroscopy. HS derivatives have good thermal properties and their decomposition temperatures were higher than 300°C. Their thermal degradation behaviour is interpreted by the strength of electron withdrawal of substituent groups. The dielectric constants of HS derivatives can be predicted by the Clausius-Mosotti equation. The calculated values are found to agree with the observed values. The dielectric constants of the polymer can be reduced by replacing hydroxy groups with alkenoyl groups, especially methacryloyl units.