Application to Flip-Chip Mounting of RF IC by Using Micro Cu-Cored Solder Balls.

概要

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Ball mount technique has not been conventionally applied to flip-chipped ICs, because of its limitation of mechanical handling. However, a method of micro ball mount shown in this paper is so unique that it is possible to operate 130μm diameter balls and to put them at 200μm intervals. Using Cu-cored solder balls whose center portion is made of a Cu ball, it works as a stay against bump melting down while a heating process. Besides, the ball stabilizes a standoff between an IC chip and an IC carrier so that the RF electrical connection between them becomes stable in terms of impedance matching at higher RF bands. This mount technique has achieved the higher standoff with around 110μm, which makes higher than a low profile gold bump bonding. It is also shown that the standoff height is much better for the RF electrical chip connection by a simulation results.
社団法人エレクトロニクス実装学会の論文