As communication information networks expand, the mobile information terminal device market is growing rapidly. greater demands are being placed on the production of low power, low weight and compact packaging technologies for Large Scale Integrated circuits. 3D-Technology promises higher integration density and lower interconnection complexity and delay. As Z-plane technology results in a much lower overall interconnection length, parasitic capacitance and thereby system power consumption can be reduced by as much as 30%. One of the important issues for 3D-packaging is development of bumping technologies which meet ultra fine pitch and low cost.
This study covered the fabrication method of fine pitch Au bump and Cu/Sn bump by electroplating and interconnection of 3D-packaging. Electroplating is one of the most popular and feasible methods for ultra fine pitch Au or Cu/Sn bump. Electroplating is affected by many parameters including Substrate, Current density, Plating solution, Temperature, Speed of stirring and electroplating process in detail.
Convenient and compatible fabrication condition of Au Bump by Electroplating method was introduced. moreover, fabrication condition of Cu/Sn bump was suggested.
Au bump and Cu/Sn bump made by electroplating were compared with in micro bump shear test and pull test conducted as a reliability test. Au bump was more uniformly formed on Ni seed layer than Cu/Ni seed layer and had no crack in the micro bump shear test contrary to Cu/Sn bump. but, Shear strength of Cu/Sn Bump was superior.
The analysis of X-ray diffraction to investigate the cause of porous Au bump was conducted. the preferred orientation was revealed as one of reason.
Au bumps on thick Ni seed layer were bonded on Au plate with changing bonding pressure to inquire into the appropriate condition of bonding. The optimized bonding condition is that bonding pressure and temperature are about 10,000kgf/㎠ and 350℃ respectively. The higher bonding pressure was gotten, the higher tensile strength was recorded until the specific point and then this gradient fell because of deformation of bump.