Photo Defined Lamination for Chip Bonding
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
This article involves the use of photo definable polyimide as a thin film solder dam when bonding integrated circuit chips with solder balls at the output pads to beam tape. A thin film of photo definable polyimide is coated or applied over copper beam tape material on which pads and interconnecting leads have been masked and etched. A further masking and material removal process is then applied to the photo definable polyimide layer, creating via holes for access to the copper inner lead pads. These exposed pads may then be gold plated without further masking steps. In assembly, the photo defined holes provide for easy alignment of the chip to the tape, while during reflow soldering the polyimide coating provides an efficient solder dam.