Chip Joining Method and Apparatus for Flexible Thin Film Modules
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
A flexible, thin polyimide film decal is metallized and circuitized to serve as a substrate in an electronic packaging scheme. The decal requires attachment to a chip using controlled collapse chip connector (C4) technology. Due to the highly flexible nature of the decal, a wrinkling of the film often occurs during the C4 chip join operation (Image Omitted) which is performed in a nitrogen atmosphere belt furnace. This wrinkling creates a separation between some C4 solder balls on the chip and their respective circuit pads on the decal. This results in an open circuit in the finished module. A tool and technique that positions, holds, and applies the necessary heat to the film during chip join keeps the film planar until the C4 joining is complete. The apparatus and its use is described in the following.