Corrosion Protection of Copper by a Self‐Assembled Monolayer of Alkanethiol

Abstract

A self-assembled monolayer of 1-dodecanethiol (DT) was formed on a copper surface pretreated using different methods. The corrosion protection abilities of the monolayer were evaluated in an air-saturated 0.51 M NaC1 solution using various techniques including electrochemical impedance spectroscopy, polarization, coulometry; weight loss, and x-ray photoelectron spectroscopy. It was found that the corrosion resistance of the monolayer was improved markedly by using a nitric acid etching method. A minimum concentration of 10 M DT was needed to form a protective monolayer. The DTmonolayer retarded the reduction of dissolved oxygen and inhibited the growth of copper oxide in the NaC1 solution. In comparison with other inhibitors, such as benzotriazole (BTA) and mercapto-benzothiazole (MBT), the DT-monolayer showed much better corrosion resistance in aqueous solution.

Thermal Stability of Self-Assembled Monolayer Copper Preservatives for Fluxless Soldering

“…The mechanism by which the monolayer preserves solderability is thought to originate from these oxygen barrier properties, preventing the formation of surface oxides that hinder solder wetting. The reduction in surface oxidation rate has been demonstrated in earlier studies [2][3][4]. Furthermore, it has been shown that the barrier properties can be enhanced through the use of longer chain molecules that increase the van der Waals interactions and provide a thicker coating [5].…”

“…This is because SAM coatings are sensitive to temperature: phase changes have been observed, the ordered alkane structure can melt and ultimately at a sufficiently high temperature the SAM molecules will desorb and decompose [6,7]. Indeed, to date it has been shown that temperature does effect barrier properties [2][3][4]. SAM coated copper surfaces stored in a freezer showed good fluxless solder wetting up to a few months after preparation, while at room temperature, solderability was only maintained for 24-48 hours.…”

The Thermal Stability of Alkanethiol Self-Assembled Monolayers on Copper for Fluxless Soldering Applications

“…The ability of SAM coatings to reduce the surface oxidation rate of the substrate metal has been demonstrated in earlier studies [9]- [11] and is attributed to the densely packed pseudocrystalline arrangement of the alkanethiol chains that retards the diffusion of oxygen and other oxidizing species including water vapor, to the underlying copper substrate. It has also been shown that barrier properties improve with increasing alkanethiol chain length due to an increase in the van der Waals interactions and greater coating thickness [12].…”

The polymeric nanofilm of triazinedithiolsilane fabricated by self-assembled technique on copper surface. Part 1: Design route and corrosion resistance

“…Enormous corrosion inhibitors, nanofilms and coatings have been accordingly explored with different fabrication techniques for copper protection. One of the most effective approaches is to prepare selfassembled monolayer (SAM) of organic inhibitors on copper surface [2]. Thus, a series of organic inhibitive compounds have been investigated, such as benzotriazole [3], thiol, dithiol and dithiocarboxylic [4], silane [5], triazinedithiol [6].…”