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GoldTin Solder Bumps for TAB Inner Lead Bonding with Reduced Bonding Pressure

GoldTin Solder Bumps for TAB Inner Lead Bonding with Reduced Bonding Pressure Tape automated bonding TAB is a suitable technology for assembling ICs with a high number of lOs. The gang bonding process usually applied requires increasing thermode forces for chips with high lead counts and narrow tolerances regarding thermode parallelism and planarity. Due to the high bonding pressure, TC bonding of Au bumps to Auplated tapes becomes critical for these applications. In order to avoid damage to the pad structure an inner lead bonding ILB process with reduced pressure is required. A tape metallisation of 0.51.0 m Sn is not sufficient for a significant reduction of thermode pressure. As an alternative, the application of an eutectic AuSn cushion which is deposited on top of the bumps is presented. A modified bumping process was developed for the deposition of the solder bumps. Soldering of the AuSn bumps to a Auplated tape was performed successfully by two techniques thermode gang bonding and laser soldering. Bond parameters and tin layer thickness were optimised. Reliability investigations by thermal ageing were performed. The special metallurgical aspects of the system were investigated with a microprobe. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Soldering & Surface Mount Technology Emerald Publishing

GoldTin Solder Bumps for TAB Inner Lead Bonding with Reduced Bonding Pressure

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0954-0911
DOI
10.1108/eb037800
Publisher site
See Article on Publisher Site

Abstract

Tape automated bonding TAB is a suitable technology for assembling ICs with a high number of lOs. The gang bonding process usually applied requires increasing thermode forces for chips with high lead counts and narrow tolerances regarding thermode parallelism and planarity. Due to the high bonding pressure, TC bonding of Au bumps to Auplated tapes becomes critical for these applications. In order to avoid damage to the pad structure an inner lead bonding ILB process with reduced pressure is required. A tape metallisation of 0.51.0 m Sn is not sufficient for a significant reduction of thermode pressure. As an alternative, the application of an eutectic AuSn cushion which is deposited on top of the bumps is presented. A modified bumping process was developed for the deposition of the solder bumps. Soldering of the AuSn bumps to a Auplated tape was performed successfully by two techniques thermode gang bonding and laser soldering. Bond parameters and tin layer thickness were optimised. Reliability investigations by thermal ageing were performed. The special metallurgical aspects of the system were investigated with a microprobe.

Journal

Soldering & Surface Mount TechnologyEmerald Publishing

Published: Mar 1, 1992

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