Manufacturing of Cu/electroless nickel/Sn-Pb flip chip solder bumps

Author

Lin, Kwang-Lung ; Liu, Yi-Cheng

Author_Institution

Dept. of Mater. Sci. & Eng., Nat. Cheng Kung Univ., Tainan, Taiwan

Volume

22

Issue

4

fYear

1999

fDate

11/1/1999 12:00:00 AM

Firstpage

575

Lastpage

579

Abstract

A process for manufacturing Cu/electroless Ni/Sn-Pb solder bump is discussed in this paper. An attempt to replace zincation with a Cu film as an active layer for the electroless Ni (EN) deposition on Al electrode on Si wafer is presented. Cu/electroless Ni is applied as under bump metallurgy (UBM) for solder bump. The Cu film required repeated etches with nitric acid along with activation to achieve a satisfactory EN deposit. Fluxes incorporating rosin and succinic acid were investigated for wetting kinetics and reflow effectiveness of the electroplated solder bump. The solder plating current density and the reflow condition for achieving solder bumps with uniform bump height were described. The Cu/EN/Sn-Pb solder system was found to be successfully produced on Al terminal in this study that avoids using zincating process

Keywords

copper; electroless deposition; electroplating; etching; flip-chip devices; lead alloys; nickel; reflow soldering; tin alloys; wetting; Cu-Ni-SnPb; electroless deposition; electroplated solder bump; flip chip solder bumps; plating current density; reflow condition; reflow effectiveness; repeated etches; under bump metallurgy; uniform bump height; wetting kinetics; Chemical processes; Chromium; Electrodes; Flip chip; Manufacturing processes; Nickel; Oxidation; Pulp manufacturing; Semiconductor films; Sputtering;

fLanguage

English

Journal_Title

Advanced Packaging, IEEE Transactions on

Publisher

ieee

ISSN

1521-3323

Type

jour

DOI

10.1109/6040.803448

Filename

803448