Evaluation of Cu-bumps with lead-free solders for flip-chip package applications

Kung Liang Lin; Edward Yi Chang; Lin Chi Shih

doi:10.1016/j.mee.2009.04.027

Evaluation of Cu-bumps with lead-free solders for flip-chip package applications

Kung Liang Lin, Edward Yi Chang^*, Lin Chi Shih

^*Corresponding author for this work

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

15 Scopus citations

Abstract

Low cost electroplated Cu-bump with environmental friendly Sn solder was developed for flip-chip applications. The seed layer used was Ti/WN_x/Ti/Cu where WN_x was used as the Cu diffusion barrier and Ti was used to enhance the adhesion between bump and the chip pad. Thick negative photoresist (THB JSR-151N) with a high aspect ratio of 2.4 was used for electroplating of copper bump and Sn solder. The Sn solder cap was reflowed at 225° for 6 min at N₂ atmosphere. No wetting phenomenon was observed for the Sn solder as evaluated by energy-dispersed spectroscopy (EDS). The Cu-bump with Ti/WN_x/Ti/Cu seed layer not only have higher shear force than the Cu-bump with Ti/Cu seed layer but also has higher resistance to fatigue failure than the Au, SnCu, SnAg bumps.

Original language	English
Pages (from-to)	2392-2395
Number of pages	4
Journal	Microelectronic Engineering
Volume	86
Issue number	12
DOIs	https://doi.org/10.1016/j.mee.2009.04.027
State	Published - 1 Dec 2009

Keywords

Copper bump
Electroplating
Lead-free

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title = "Evaluation of Cu-bumps with lead-free solders for flip-chip package applications",

abstract = "Low cost electroplated Cu-bump with environmental friendly Sn solder was developed for flip-chip applications. The seed layer used was Ti/WNx/Ti/Cu where WNx was used as the Cu diffusion barrier and Ti was used to enhance the adhesion between bump and the chip pad. Thick negative photoresist (THB JSR-151N) with a high aspect ratio of 2.4 was used for electroplating of copper bump and Sn solder. The Sn solder cap was reflowed at 225° for 6 min at N2 atmosphere. No wetting phenomenon was observed for the Sn solder as evaluated by energy-dispersed spectroscopy (EDS). The Cu-bump with Ti/WNx/Ti/Cu seed layer not only have higher shear force than the Cu-bump with Ti/Cu seed layer but also has higher resistance to fatigue failure than the Au, SnCu, SnAg bumps.",

keywords = "Copper bump, Electroplating, Lead-free",

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doi = "10.1016/j.mee.2009.04.027",

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AU - Lin, Kung Liang

AU - Chang, Edward Yi

AU - Shih, Lin Chi

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N2 - Low cost electroplated Cu-bump with environmental friendly Sn solder was developed for flip-chip applications. The seed layer used was Ti/WNx/Ti/Cu where WNx was used as the Cu diffusion barrier and Ti was used to enhance the adhesion between bump and the chip pad. Thick negative photoresist (THB JSR-151N) with a high aspect ratio of 2.4 was used for electroplating of copper bump and Sn solder. The Sn solder cap was reflowed at 225° for 6 min at N2 atmosphere. No wetting phenomenon was observed for the Sn solder as evaluated by energy-dispersed spectroscopy (EDS). The Cu-bump with Ti/WNx/Ti/Cu seed layer not only have higher shear force than the Cu-bump with Ti/Cu seed layer but also has higher resistance to fatigue failure than the Au, SnCu, SnAg bumps.

AB - Low cost electroplated Cu-bump with environmental friendly Sn solder was developed for flip-chip applications. The seed layer used was Ti/WNx/Ti/Cu where WNx was used as the Cu diffusion barrier and Ti was used to enhance the adhesion between bump and the chip pad. Thick negative photoresist (THB JSR-151N) with a high aspect ratio of 2.4 was used for electroplating of copper bump and Sn solder. The Sn solder cap was reflowed at 225° for 6 min at N2 atmosphere. No wetting phenomenon was observed for the Sn solder as evaluated by energy-dispersed spectroscopy (EDS). The Cu-bump with Ti/WNx/Ti/Cu seed layer not only have higher shear force than the Cu-bump with Ti/Cu seed layer but also has higher resistance to fatigue failure than the Au, SnCu, SnAg bumps.

KW - Copper bump

KW - Electroplating

KW - Lead-free

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Evaluation of Cu-bumps with lead-free solders for flip-chip package applications

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Keywords

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