Preparation of Three-dimensional Micro Structure of Cu-Sn Intermetallic Compound by Micro-electroplating

• Main Authors: Jin-Lun Liu, 劉謹綸
• Other Authors: Jing-Chie Lin
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/5hf25n

碩士 === 國立中央大學 === 材料科學與工程研究所 === 106 === In this study, micro-anode guided electroplating was used to manufacture three dimensional micro-structures of Cu-Sn intermetallic compound. The electroplating system uses a platinum wire with a wire diameter of 125 μm as an anode, and a copper wire with a diameter of 0.643 mm as a cathode, which is electroplated in an electroplating bath containing copper sulfate, stannous sulfate, sodium citrate and ascorbic acid to manufacture three dimensional micro-structure with two metal elements of copper and tin. The goal of this research is to firstly investigate the effect of adding ascorbic acid on the surface morphology, chemical composition, crystal structure and reduction potential of the micro-column in the plating bath, and then seek to find the best electroplating conditions of electroplating micro-columns with two metal elements of copper and tin. Then using these conditions to research the feasibility of making micro-helix, and studying the influence of micro-helix electroplating angle and process parameters on micro-helix size and the variation of wire diameter. The results showed that after adding ascorbic acid to the electroplating bath not only improved the surface morphology of the micro-column, but also promotes the transformation from a grain-like appearance to a flat and smooth surface. When the bias is set at 3.50 V and the gap is controlled at 140 μm, the copper and tin binary metal micro-column obtained by electroplating have the best surface morphology. After analyzing, its chemical composition is Cu: 65.9 ± 3.1 at.% and Sn: 34.1 ± 3.1 at.%. The crystal structure analysis shows that the crystal structure is Cu6Sn5, Cu coexisting. The mechanical properties of the micro-column were measured by a nanoindenter. The hardness was estimated to be 1.51 ± 0.10 GPa and the reduced modulus was 73.31 ± 5.57 Gpa. The corrosion resistance was measured by electrochemical measurement. The corrosion current (Icorr) was 0.04×10-2 mA/cm2, linear polarization resistance (RLP) is 2877 ohm. The results of electroplating micro-helix showed that the larger the changed in electric field strength (△Ed12) between the first coil diameter of the micro-helix and the second coil diameter is, the shorter the electrochemical deposition time is; and the more uniform the micro-helix diameter is, the result shows : electrochemical deposition angle 15 ° and process parameter 2 is the best electroplatimg parameter of copper-tin intermetallic compound helix because the diameter of helix wire d1、d2、d3 are the most close, the d2 / d1 ratio is 107 %, the d3 / d1 ratio is 127 %.