Thermal compression bonding with non-conductive adhesive of 30μm pitch Cu pillar micro bumps on organic substrate with bare Cu bondpads

Abstract

The assembly capability of 30μm ultra-fine pitch Cu pillar flip chip interconnect on a two-layer FCCSP organic substrate with a chip size of 8mm × 8mm × 0.1mm chip was demonstrated by using thermal compression bonding with non-conductive paste (TCB-NCP) to mitigate the issue of coefficient of thermal expansion (CTE) mismatch between silicon chip and organic substrate. A method, developed to quantify post-bonding misalignment, was used to study the effects of different bonding approaches. This paper reports on details of the bill of materials (BoM); description of method to determine mis-alignment; the effects of different bonding approach; assembly challenges; and reliability assessment involving the solder cap volume effects on flip chip joint fatigue life under temperature cycling tests.