Investigations of laser soldered TAB inner lead contacts

Author

Zakel, Elke ; Azdasht, Ghassem ; Reichl, Herbert

Author_Institution

Technol. der Mikroperipherik, Tech. Univ., Berlin, Germany

Volume

14

Issue

4

fYear

1991

fDate

12/1/1991 12:00:00 AM

Firstpage

672

Lastpage

679

Abstract

The results of tape automated bonding (TAB) inner lead bonding with a pulsed Nd:YAG laser are presented. Tapes with three metallizations (Sn, Ni-Sn, and Au) were laser soldered to bumps consisting of gold and gold-tin. The pull strength of laser-soldered TAB contacts was optimized by variation of laser power and reliability investigations were performed. An accumulation of eutectic 80/20 Au-Sn solder in the bonded interface results in a strong degradation due to Kirkendall pore formation in the ternary Cu-Sn-Au system. The application of a tape with a diffusion barrier on Ni inhibits this effect. However, during thermal aging these contacts show a strong degradation of pull forces which is attributed to the formation of brittle intermetallic compounds of the elements Ni, Sn, and Au in the contact area. The contacts show optimal pull forces and a minimal degradation after thermal aging

Keywords

ageing; chemical interdiffusion; integrated circuit technology; laser beam machining; metallisation; soldering; tape automated bonding; Kirkendall pore formation; NiSn-Au; Sn-Au; brittle intermetallic compounds; chip microconnection; diffusion barrier; eutectic Au-Sn solder; laser soldered TAB inner lead contacts; metallizations; pull force degradation; pull strength; pulsed Nd:YAG laser; reliability; tape automated bonding; ternary Cu-Sn-Au; thermal aging; Aging; Bonding; Gold; Lead; Metallization; Optical pulses; Power lasers; Thermal degradation; Thermal force; Tin;

fLanguage

English

Journal_Title

Components, Hybrids, and Manufacturing Technology, IEEE Transactions on

Publisher

ieee

ISSN

0148-6411

Type

jour

DOI

10.1109/33.105116

Filename

105116