Title :
Thermal stability of various ball-limited-metal systems under solder bumps
Author :
Mizuishi, Ken´Ichi ; Mori, Takao
Author_Institution :
Hitachi Ltd., Tokyo, Japan
Abstract :
Thermal stability is discussed of ball-limited-metal (BLM) layers formed under controlled-collapse solder (lead-5 wt.% tin) bumps for flip-chip interconnections. All BLM systems used here consist of a triple-layer deposit of Cr or Ti as an adhesive; Ni, Mo, Pd, or Pt as a barrier; and Au as a surface metal. Using test chips with these BLM systems, mechanical pull-strength values of solder-bump joints are obtained. These values are associated with thermal phenomena at the interface between the BLM and solder layers. The chips with Ti adhesive layers show generally superior solder-joint strength to those with Cr layers, independently of the barrier metal used. This is due to the presence of a joint fracture mode closely related to the kind of adhesive metal. Among the BLM systems examined, Ti/Ni/Au is found to provide the most reliable solder joints. This is successfully utilized as a BLM system for GaAs devices
Keywords :
flip-chip devices; integrated circuit technology; packaging; soldering; stability; thermal analysis; Cr; GaAs devices; IC packaging; Mo; Pd; Pt; Sn-Pb; Ti-Ni-Au; adhesive; ball-limited-metal systems; barrier layer; flip-chip interconnections; interface; joint fracture mode; mechanical pull-strength values; solder bumps; solder-joint strength; surface metal; thermal stability; triple-layer deposit; Chromium; Copper; Gallium arsenide; Gold; Lead; Reflow soldering; System testing; Thermal stability; Tin; Wiring;
Conference_Titel :
Thermal Phenomena in the Fabrication and Operation of Electronic Components: I-THERM '88, InterSociety Conference on
Conference_Location :
Los Angeles, CA
DOI :
10.1109/ITHERM.1988.28679
