SELEO CP – New Conductive Polymer Direct Metallization - Sponsored Whitepaper

Due to reduced investment and running costs, their environmental friendliness and the low space requirements, direct metallization (DM) processes have become very popular in the 1990s. The DM sequences itself can be divided into three subgroups, the conductive polymer based, the Carbon based and the Pd colloid based DM processes. While the latter two at some stage require an etch cleaning step, the conductive polymer (CP) sequences are highly selective by nature. With microvia plating and the global penetration of HDI mass production new limitations for some DM processes have been encountered. The CP versions however proved to give excellent, persistent and high yield results.

The Special Requirements for HDI Microvia Production In order to be successful in plating vias smaller than 250 µm in diameter two main criteria have to be fulfilled. Each and every single entity has to be wetted and the deposited metallization layer should be deposited with sufficient throw to keep dwell times in normal ranges. With conductive polymers wetting is excellent partly due to the fact that most of the process electrolytes are run at high temperatures. The conductive layer is very thin, satisfying all throwing power requirements. The disadvantage of several DM methods in particular with blind microvia plating are due to missing wet ability or required excessive etching, both leading to voids of folding.

Figure 1: Overview Process Sequence Conductive Polymer