Microfilled via: an enabling technology for high density high performance high volume BGA substrates

Abstract

Microfilled Via (MfVia) is an enabling technology on which a superior and economical BGA substrate manufacturing is based. The main technology feature is a new method of creating a micro via by substituting the traditional costly drilling and plating process with a mass photoimageable via hole creation and stencil hole filling process. Via holes are later covered by copper through a foil lamination process to create a flat surface. Besides a dramatic reduction in the manufacturing cost, the new process also provides the following advantages: (1) True pad on via, (2) Superior Cu to photoimageable dielectric adhesion due to the lamination process, (3) High density outer layer process as the extra Cu plating on the outer layer is eliminated, (4) Low cost blind and buried via due to the sequential layer buildup and photo imaged vias. This high density via technology allows easy implementation of high pin-count substrates, even with the current generation line and spacing rule, such as 0.004"/0.004". This paper discusses the manufacturing, characterization and reliability of a BGA package manufactured using the microfilled via technology.