PREVENTING ARTIFACTS DUE TO UNDERFILL IN FLIP CHIP IMAGER ASSEMBLY

摘要

A CMOS imager assembly may include an integrated circuit (IC) having an active-pixel image sensor that is mounted on a printed circuit board (PCB) substrate using flip chip packaging technology. The IC and the PCB may be physically and electrically connected to each other through multiple electrically conductive connectors. An underfill material (which may include an anti-reflective material) may, during assembly, be introduced around the connectors in the space between the IC and the PCB. A chemical or physical discontinuity on the integrated circuit may, during assembly, prevent the underfill material from entering an area framed by the discontinuity, which may include the pixel array of the image sensor. The discontinuity may include a dam-like structure built up on the IC, a trench-like structure created on the IC, or a low surface tension material that has been applied to the surface of the IC.

主权项

1. A computer system, comprising:
a printed circuit board; an integrated circuit device comprising an image sensor pixel array; a plurality of electrically conductive interconnect structures; and a composite underfill material comprising a polymer and one or more fillers; wherein the integrated circuit device is coupled to the printed circuit board by the interconnect structures at respective points on the integrated circuit device and the printed circuit board such that the image sensor pixel array faces the printed circuit board; wherein the composite underfill material envelopes at least a portion of each of the interconnect structures in a space between the integrated circuit device and the printed circuit board; and wherein a chemical or physical discontinuity on the integrated circuit device surrounds the image sensor pixel array and prevents the composite underfill material from extending over the image sensor pixel array.