Via filling applications for IC Substrate and in particular Flip Chip BGA - Sponsored Whitepaper

IC substrate fabrication has been relying now for several years on the formation of Blind Micro Vias (BMV) as connectors between different layers. These BMVs are Cu plated and usually completely filled to improve the reliability of connections between different Cu layers compared to the traditional conformal plating. The complete filling enables direct stacking of BMVs (Fig 1 right), a further approach to miniaturize features on the IC substrate. Especially BGAs could be reduced in spacing by leaving away the extra contact pad which was required.