Characterization of Electrophoretic Photoresist for Superior Resolution in High Density Packaging

摘要

As the demands of leading edge interconnect technology move the PWB industry toward 1- and 2-mil feature resolution, new manufacturing technologies and strategies are required. In recent years, many PWB fabricators have considered using liquid resists as a way to improve fine line resolution capabilities. An alternative to current liquid technology is that of electrodeposited (ED) photoresists. An electrodepositable photoresist offers many advantages which include: very fine feature capability; excellent 3-dimensional coverage and adhesion to surfaces; very thin, well-controlled film thickness; and the ability to form landless vias. Perhaps the most intriguing advantage of the ED coating process is the ability to conformally coat any conductive surface completely and uniformly. This means that the micro-etched texture on the copper and the holewall surfaces of vias, along with anomalies such as pits and scratches, will be intimately coated, not tented over. It is this conformal coating ability, coupled with the exceptional flexibility of the thin resist film, that results in superior adhesion to the base metal and creates the best possible condition for imaging fine features. And, it is the conformal coating ability that makes landless vias possible.