Elsevier

Materials Letters

Volume 65, Issue 4, 28 February 2011, Pages 698-701
Materials Letters

A novel corrosion self-protective copper/liquid microcapsule composite coating

https://doi.org/10.1016/j.matlet.2010.11.024Get rights and content

Abstract

Traditional methods to protect copper coating still exists with some shortages such as environmental pollution and high cost caused by multi-step processes. In this letter, Cu/liquid microcapsule composite coating was prepared by electroplating method. The corrosion resistance of the composite was investigated by means of electrochemical technique. The result of the XPS analysis proved that a thin hydrophobic film could form on the composite surface because of the slow release of microcapsules. This film improved greatly the corrosion resistance of composite coating. Especially, the corrosion inhibition efficiency reached up to 97.6% compared with that of the copper coating when the composite was stored in air for 30 days (d) at 25 °C.

Introduction

Copper (Cu) is a preferred metal in the chemical and microelectronics industries due to its high electrical conductivities and lower cost than gold or silver. One of the major disadvantages in copper applications is that it corrodes easily in the course of transport, storage and using, which leads to inferior device performance and failure. Traditional methods to prevent copper corrosion are surface passivation [1], [2], [3], [4], [5], self-assembly technology [6], [7], [8] and different coatings for protection [9], [10], [11], [12]. Although these methods as subsequent treatments have well solved the problem of copper corrosion, they cause many concerns such as environmental pollution of Cr6+, high cost caused by multi-processes and so on.

In this letter, a simple and convenient method, electrolytic co-deposition was used to prepare the Cu/microcapsules containing liquid core material (BH-102 hydrophobic agent) composite coating. One of the promising advantages of this composite is that the encapsulated liquid core material can be released gradually and forms a protective film on the copper surface. This hydrophobic film as a long-term film can effectively improve the corrosion resistance of coating on account of its exceptional chemical stability in air at room temperature and excellent water-repellent property. Additionally, this composite does not need subsequent treatment, also avoids environmental pollution and saves money.

Section snippets

Experimental

Liquid microcapsule was prepared by using the phase separation method. 1 ml liquid core material (BH-102 hydrophobic agent whose main component is organic siloxane) was added dropwise to a beaker containing 20 ml shell material (methyl cellulose, cP 15–25) aqueous solution under stirring (1000 rpm) at room temperature. Five minutes later, 1–2 drops Span 80 was added into the emulsion. Subsequently adding 5 ml anhydrous alcohol to the mix dropwise, and then decreased the stirring speed gradually.

Results and discussion

Depicted in Fig. 1 are the surface morphologies of the newly prepared composite and the composite stored in air for 30 days (d) at 25 °C. It can be seen that many spherical objects distribute evenly on the composite surface, as observed in Fig. 1a. The EDS analysis of the spherical objects reveals strong C, O and Si signals, which are the main elements of the core material of the microcapsule, indicating the existence of microcapsules. These microcapsules in the composite shrink obviously after

Conclusion

Instead of the traditional methods to improve the corrosion resistance of the copper coating, a Cu/liquid microcapsules composite coating is prepared by electric co-deposition method. It is confirmed that the slowly released core material from the microcapsules does not react with Cu to produce the new phase structure, but a protective oil film forms on the composite surface. This film can effectively prevent corroding from the corrosion medium, which makes the composite exhibit the excellent

Acknowledgement

The authors acknowledge the financial support of the National Natural Science Foundation of China under Grant No. 50771010.

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