Process Development and Reliability of Microbumps

The use of flip-chip bonding technology on gold-tin (AuSn) microbumps for flip-chip packaging is becoming increasingly important in the electronics industry. Some of the main advantages of AuSn system over solder flip-chip technology are suitability for very fine pitch interconnection and fluxless b...

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Bibliographic Details
Published in:IEEE transactions on components and packaging technologies 2010-12, Vol.33 (4), p.747-753
Main Authors: Lim, Sharon Pei-Siang, Rao, Vempati Srinivasa, Wai Yin Hnin, Wai Leong Ching, Kripesh, Vaidyanathan, Lee, Charles, Lau, John, Milla, Juan, Fenner, Andy
Format: Article
Language:English
Subjects:
Assembly
AuSn solder
Bonding
Design of experiments
Electronics
Flip chip
Flip chip solder joints
Gold alloys
microbumps
Microorganisms
Modules
Packaging
Pressure distribution
Reliability
Semiconductor device manufacture
Semiconductors
Silicon
solder joint reliability
Solders
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Summary:The use of flip-chip bonding technology on gold-tin (AuSn) microbumps for flip-chip packaging is becoming increasingly important in the electronics industry. Some of the main advantages of AuSn system over solder flip-chip technology are suitability for very fine pitch interconnection and fluxless bonding. Fluxless flip-chip assembly is in demand especially for medical applications and optoelectonics packaging. Here, we report the assembly process development of a silicon stacked module assembled with AuSn microbumps to meet the stringent reliability. The effects of bond pressure distribution, bond temperature and alignment accuracy were found to be critical in this stacked silicon using AuSn microbumps. A three-factor design of experiment was carried out to investigate the effects of assembly parameters such as bonding pressure, temperature and time on contact resistance and AuSn solder wetting on the electroless nickel and gold under bump metallization. Results showed that higher bond force is undesirable and contributes to passivation cracking and deformed AuSn joint with AuSn solder being squeezed out of the joint during bonding. The reliability result of the flip-chip assembly of stacked silicon module using AuSn microbumps was presented.
ISSN:1521-3331
1557-9972
DOI:10.1109/TCAPT.2010.2046487