Adhesive film and tacking pads for printed wiring assemblies

摘要

A self supported underfill film adhesively bonds surface mount integrated circuit packages to a printed circuit board. The printed circuit board has conductive traces and exposed conductive pads on the surface. Solder paste is printed on the conductive pads, and one or more additional solder paste deposits are printed in an area outside the conductive pads to serve as tack pads for a film adhesive. The film adhesive is strategically positioned on the printed circuit board over the tack pads and near the conductive pads, and the surface mount integrated circuit package is then placed on the board so that the conductive pads on the package align with the conductive pads on the board. The film adhesive softens when the package is soldered to the board, and the film ultimately serves as an underfill to increase the mechanical integrity of the solder joints.