Fabrication of Ni-Mn Microprobe Structure with Low Internal Stress and High Hardness by Employing DC Electrodeposition

Kuan-Hui Cheng,Ping-Huan Tsou,Tzu-I Ho,Jung-Tang Huang,Chang-Cheng Lan,Chao-Sung Lin,Fu-Je Chen,Chun-Ying Lee

doi:10.1155/2014/890814

Abstract

Due to its widely tunable mechanical property and incompatibility with most solders, Ni-Mn alloy can become a viable candidate in the fabrication of testing probe for microelectronic devices. In this study, the electrodeposition of Ni-Mn alloy in nickel sulphamate electrolyte with the addition of manganese sulphate was investigated under direct current (DC) power source. The effects of current density and Mn2+concentration in the electrolyte on the coating composition, cathodic efficiency, microstructure and mechanical properties were explored. The results showed that the raise of the Mn2+concentration in the electrolyte alone did not effectively increase the Mn content in the coating but reduce the cathodic efficiency. On the other hand, increasing the current density facilitated the codeposition of the Mn and rendered the crystallite from coarse columnar grain to the refined one. Thus, both hardness and internal stress of the coating increased. The fabrication of testing probes at 1 A/dm2was shown to satisfy the high hardness, low internal stress, reasonable fatigue life, and nonsticking requirements for this microelectronic application.

Highlights

Accompanying the evolution of integrated circuits (ICs) chips toward miniaturization and complicated functionality, the demand on the development of high compaction probe card for quality assurance has posed a difficult engineering challenge
The development of the probe structure with high dimensional accuracy and high strength is crucial for the IC industry [1,2,3]
For the Mn2+ concentration was higher than 10 g/L, the Mn content in Internal stress Deposit manganese content

Summary

Introduction

Accompanying the evolution of integrated circuits (ICs) chips toward miniaturization and complicated functionality, the demand on the development of high compaction probe card for quality assurance has posed a difficult engineering challenge. Ni-Mn alloy has superior mechanical strength and hardness and has been successfully used in preparation of microsystem devices, such as microgear and contact spring [8, 9]. It serves as a potential candidate for the fabrication of microprobe structure. The special requirement for nonsticking property with most solder bumps and connecting pads was not reported It is, the goal of this study to investigate the plausible fabrication process of Ni-Mn microprobe structure with high strength and low internal stress by controlling the electrolyte bath and current density in the electrodeposition

Experiment

Results and Discussion

Conclusion