Title :
Reflowable Sn-Pb bump formation on Al pad by a solder bumping method
Author :
Ogashiwa, T. ; Arikawa, T. ; Murai, H. ; Inoue, A. ; Masumoto, T.
Author_Institution :
Tanaka Denshi Kogyo Ltd., Mitaka, Japan
Abstract :
A new solder bump material for reflow soldering on an Al pad was developed by using a rapidly solidified 60 Sn-29 Pb-5 Sb-1 Zn-5 Ag(mass%) alloy wire. The balls made from the wire by arc discharge in Ar+10%H2 gas were bonded on an Al-1mass%Si film by thermosonic bonding at 398 K using a wire bonding machine. The bonding to the Al-Si film was made by the interdiffusion of Sn, Sb, Ag and Al through microfissures which occurred on the film surface. The as-bonded bump can be spheroidized by heating at 473 K with an inactivated rosin base flux. The shear strength of the reflowed bump is 79 MPa and decreases with increasing reflow temperature. According to the thermal fatigue life test of the solder bump applied to the flip-chip bonding, the striations formed by the fatigue fracture were observed to generate at very fine intervals of 0.08-0.12 μm. These results are good enough to expect practical application of the direct solder bump formation technique on Al pad
Keywords :
flip-chip devices; integrated circuit interconnections; lead alloys; lead bonding; life testing; reflow soldering; shear strength; thermal stresses; tin alloys; 0.08 to 0.12 micron; 398 K; 473 K; AlSi; SnPbSbZnAg; arc discharge; flip-chip bonding; inactivated rosin base flux; microfissures; reflow soldering; reflow temperature; reflowable bump formation; shear strength; solder bumping method; thermal fatigue life test; thermosonic bonding; wire bonding machine; Aluminum alloys; Arc discharges; Bonding; Fatigue; Heating; Reflow soldering; Surface discharges; Temperature; Tin; Wire;
Conference_Titel :
Electronic Components and Technology Conference, 1995. Proceedings., 45th
Conference_Location :
Las Vegas, NV
Print_ISBN :
0-7803-2736-5
DOI :
10.1109/ECTC.1995.517843
