Title :
Laser-assisted bump transfer for flip chip assembly
Author :
Wang, C.H. ; Holmes, A.S. ; Gao, S.
Author_Institution :
Dept. of Comput. & Electr. Eng., Heriot-Watt Univ., Edinburgh, UK
Abstract :
This paper describes a novel laser-assisted bumping technique for flip chip assembly. Copper bumps, with gold bonding layers and intermediate nickel barriers, are fabricated by UV lithography and electroplating on quartz wafers with pre-deposited polyimide layers. The bumps are thermosonically bonded to their respective chips and then released from the carrier by laser machining of the polyimide layer, using laser light incident through the carrier. Bump fabrication, parallel bonding, and chip release have been successfully demonstrated for test chips having 28 peripheral I/Os on 127 μm pitch. Visual inspection of bump cross-sections and individual bump shear test measurements have been carried out for chips bumped by the new method
Keywords :
electroplating; flip-chip devices; integrated circuit bonding; integrated circuit interconnections; integrated circuit packaging; laser beam machining; laser materials processing; lead bonding; ultraviolet lithography; 127 micron; Cu-Ni-Au; SiO2; UV lithography; bump cross-sections; bump fabrication; bump shear test measurements; chip release; copper bumps; electroplating; flip chip assembly; gold bonding layers; intermediate nickel barriers; laser light incidence; laser machining; laser-assisted bump transfer; laser-assisted bumping technique; parallel bonding; peripheral I/O pitch; polyimide layer; pre-deposited polyimide layers; quartz wafers; test chips; thermosonically bonded bumps; visual inspection; Assembly; Closed loop systems; Copper; Flip chip; Gold; Lithography; Nickel; Polyimides; Testing; Wafer bonding;
Conference_Titel :
Electronic Materials and Packaging, 2000. (EMAP 2000). International Symposium on
Conference_Location :
Hong Kong
Print_ISBN :
0-7803-6654-9
DOI :
10.1109/EMAP.2000.904137
