John E. Graves

Development of a new, more efficient and environmentally friendly method of producing high density interconnects – the “PRIME” process

In September 1998 six European companies involved in PCB manufacturing and electronic packaging started collaborating in a development project known as “PRIME”. The “Program for Re‐engineering and Innovating (PCB) Manufacturing and Equipment” project lost one of its original members in late 1999, and Coates Circuit Products joined as the dielectric supplier. The project is now approaching the mid‐term assessment (MTA), where alternative production scenarios will be discussed and the most attractive carried forward to fabricate test vehicles and ultimately demonstrator patterns. Some essential features of the project have already been demonstrated and these initial results will be presented.

Horizontal processing for metallizing microvias

The demand for higher operating speeds and increasing densification in electronic packages is driving designers to reduce feature sizes in order to accommodate increases in I/O counts. Consequently, printed circuit board manufacturers are turning to new manufacturing techniques and new materials in order to meet these demands from their customers. Sequential build‐up is one such technique and a plethora of new materials is available to support these innovative routes to high‐density interconnect circuitry. The basic concept involves the addition of extra layers of dielectric and copper on to a multi‐layered board. The additional circuitry is then connected to the underlying board using suitably formed microvias. Focuses on the metallization of microvias using a straight‐through horizontal metallization process. Particular emphasis is placed on the importance of equipment design, the chemistry of the solutions used and optimization of fluid exchange to ensure good coverage of these small features.