Laser Etching of a Polyimide Film Chip Carrier to Reduce Wrinkling at Chip Join
Original Publication Date: 1988-Jun-01
Included in the Prior Art Database: 2005-Feb-15
Controlled collapse chip connector (C-4) solder joints are used to attach various chips to polyimide film chip carriers (known as a "PFCC" or "decal"). During the chip attach process, the carrier is subjected to high temperatures in the chip join furnace during which a significant amount of wrinkling occurs in the C-4 area of the carrier. This wrinkling is caused by the different thermal expansion coefficients of polyimide and the metallization. This wrinkling results in non-wetting and crushing of the C-4 pads, making proper attachment of the chip impossible.