Characterization of Mechanical Properties of Electroplated Nickel Film and Ni3Sn4 Intermetallic Compound

• Main Authors: Li-Jung Tai, 戴禮榮
• Other Authors: Enboa Wu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/02547359579143905506

碩士 === 國立臺灣大學 === 應用力學研究所 === 94 === With the improvement of filpchip technique and chip efficiency, temperature problem is becoming an important issue. When chip is working, the high temperature easily causes the packaging to deform because chip and substrate have different thermal expansion coefficients (CTE), and the high stress resulting from the deformation will make I/O connections fracture. Numerical methods have been widely used to analysis the stress distribution and to predict the reliability of packaging, but only if the material properties of these connections are known can we predict the stress distribution very precisely. Under-bump metallization (UBM) consists of many metal thin films, and these metal films often exhibit different mechanical properties from those of their bulk materials. Furthermore, during reflow process, UBM will react with solder bump to form a hard and brittle material-intermetallic compound (IMC). UBM and IMC are equally important in reliability analysis, but they are so thin that their properties are difficult to be measured. Therefore, the objective of this study is to develop an inverse method to detect the mechanical properties of nickel film and nickel IMC. In this study, specimens having multi-layer structure, such as Ni/Si, Ni3Sn4/Ni/Si, Ni3Sn4/Ni Foil, were produced. By using optical measurement technique and inverse method, which includes finite element method (FEM) and genetic algorithm (GA), the Young’s modulus and CTE of the unknown material can be obtained simultaneously. The inversely calculated results of Ni and Ni3Sn4 were also verified by relevant literatures and material theories. Various growing conditions of electroplated nickel or Ni3SN4 will result in different mechanical properties, and that also causes different effects on packaging. Hence, this study was expected to offer more data about Ni and Ni3Sn4 for the stress analysis of packaging.