The process and pastes for the via hole plugging of HDI PCBs

Abstract

Purpose The purpose of this paper is to present the materials and process considerations and solutions that enable the safe use of plugging pastes in high density interconnection (HDI) printed circuit boards (PCBs) designed to operate at higher temperatures. Design/methodology/approach The paper introduces the concept of microvia plugging and the issues that are important in influencing HDI PCB reliability. Plugging pastes and their properties are discussed along with the various plugging processes that can be used. The advantages and disadvantages of each type of process are compared and contrasted. Findings The creation of via holes and the filling of these interconnection holes or buried vias and their subsequent copper plating is one of the key processes in HDI technology. In future, the importance of plugging will increase, particularly on account of the growing demand for copper plating and dimensional stability. Research limitations/implications The paper highlights the importance of making the correct selection of materials and processing methodologies and details the implications of these choices. Originality/value The paper describes the different approaches that can be used for filling microvias and details the issues, advantages and disadvantages of the various approaches. The paper particularly focuses on the special demands on plugging pastes used in higher temperature range applications.