Fengtian Hu

Superhydrophobic and anti-corrosion Cu microcones/Ni–W alloy coating fabricated by electrochemical approaches

In this work, we present a simple method for fabricating a microstructured Cu/Ni–W alloy coating by combining electroless and electro deposition. Field emission scanning electron microscopy (FESEM) results show that a layer of Ni–W alloy has covered uniformly the conical surface of Cu microcone arrays, forming a multilayer coating. The Tafel curve shows the prominent anti-corrosion property of the as-deposited Ni–W film. Wettability results reveal that the water contact angles can be increased from 106° to 153.2° by adjusting the electrodeposition time of the Ni–W layer. The liquid–solid–air contact mode between the superhydrophobic Ni–W hemisphere decorated Cu microcone array and the water drop is briefly discussed. This work also showed potential for use in a wide range of applications, such as the commercial production of anti-wetting and anti-corrosion devices.

A low-temperature solid-state bonding method using Ag-modified Cu microcones and Ag buffer

A novel low-temperature solid-state bonding method that Cu microcones coated with Ag and Ag buffer has been proposed. Thin Ag layer was used to prevent the oxidation of Cu microcones and Ag layer of several micrometers was used as a buffer layer between Cu microcones and Cu bumps. No brittle IMCs formed in the interfaces.

Research on the interfacial reaction and mechanism of Cu/Sn/Ni copper pillar bump

Copper pillar bump interconnect technology, with its good electrical properties and electromigration resistance, is becoming the next key technology for fine pitch interconnection of chips. The study of the effect of copper pillar bump size on the interfacial diffusion reaction has directive significance to the application of copper pillar bump. This paper focuses on the effect of size on the reliability of copper pillar bump. We use the multi-layer electroplating method to prepare Cu/Sn/Ni copper pillar bump sandwich structure with different diameters of Φ20μm and Φ100μm. We find that the reduction of bump size will promote the growth of interfacial intermetallic compound (IMC). A void growth model in the copper pillar bump is explored by investigating Kirkendall voids and the growth of IMC in Φ20μm Cu/20μmSn/Ni copper pillar bumps.

Effects of Cu orientation on the microstructure of Sn-2Ag-2.5Zn /Cu interface

The effects of Cu orientation on the microstructure and growth of IMCs in Sn-2Ag-2.5Zn /Cu solder joints were studied. After reflowing at 250 °C for 10 s, the continuous scallop-like IMCs Cu6Sn5 in Sn-2Ag-2.5Zn /polycrystalline Cu solder joint were more flat and thinner than that on (110), (111) oriented Cu substrates. The grain size of IMC on single crystal Cu substrates was larger than that of IMC on polycrystalline Cu. While during aging time, the growth rate of IMC on polycrystalline Cu substrates was slower, compared with that on (110), (111) oriented Cu substrates, and the thickness of IMC on (110), (111) oriented Cu substrates showed no visible differences, It was observed that the thickness of IMC was proportional to the square of the time in aging process.