Micro-ball bump for flip chip interconnections

K. Shimokawa, E. Hashino, Y. Ohzeki, K. Tatsumi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

14 Citations (Scopus)


Micro-ball bump technology has been developed for flip chip (FC) interconnections. This technology is based on (1) a production method of fine metal balls (micro-balls) and (2) a gang-bonding method for forming bumps (micro-ball bumps) on chip electrodes. Solder balls of 60-150 mm and gold balls of 35-100 mm in diameter were prepared with extremely uniform diameters and high sphericity. After holding these micro-balls on through-holes of an arrangement plate by a vacuum suction method, the micro-balls were transferred onto the electrodes of the chips in order to form the micro-ball bumps. An excess ball eliminating system and a ball bouncing system were developed for arranging the ball successfully on the plate. The cycle time of the originally developed mounter was 20 seconds for a chip with 300 bumps. Both bumping on a single chip and on multiple chips in a wafer were possible. The micro-solder bumps were formed onto the electrodes covered with under bump metals (UBMs). The micro-solder-balls of 150 mm in diameter were transferred onto the flux printed electrodes of a chip with 220 mm pitch and 45×45 area array. The micro-solder bumps were uniform in composition, volume, and height because of the use of the micro-solder-balls with precisely controlled diameter and composition. Using the micro-gold-balls of 35 mm in diameter, the bumps with 50 mm pitch were formed on Al pads by means of thermocompression bonding. The proposed micro-ball bump technology could be applied to bumping not only for FC interconnections, but also for TABs.

Original languageEnglish
Title of host publication1998 Proceedings - 48th Electronic Components and Technology Conference, ECTC 1998
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages5
ISBN (Print)0780345266
Publication statusPublished - 1998 Jan 1
Externally publishedYes
Event48th Electronic Components and Technology Conference, ECTC 1998 - Seattle, United States
Duration: 1998 May 251998 May 28

Publication series

NameProceedings - Electronic Components and Technology Conference
VolumePart F133492
ISSN (Print)0569-5503


Conference48th Electronic Components and Technology Conference, ECTC 1998
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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