Study On Preparation Process Of Copper Nanoparticles Used For Inkjet Printing

Inkjet printing can print inductive ink on various substrates directly; it has been frequently used for the fabrication of electronic products. And this green technology has shown great potential to replace the traditional methods of producing PCB conductive pattern. The key point of inkjet printing is to develop a conductive ink of excellent performance. In PCB industry, the silver nanoparticles conductive ink has been commercialized; however, the high cost makes it impossible for large scale application. Because of the low cost, Cu nanoparticles become the research focus, and it is expected to replace silver nanoparticles.However, Cu nanoparticles have a critical limitation that they are readily oxidized once exposed to air. The presence of a surface oxide layer would critically degrade the electrical property, and it will also increase the sintering temperature. But the other materials in electrical production cannot withstand high temperature. In considerations of these factors, we need Cu nanoparticles with good antioxidant activity and low sintering temperature. Cu nanoparticles30-50nm in size is synthesized by modified polyol method. Copper(II)sulfate pentahydtace acts as metal precursor, Sodium phosphinate monohydrate acts as a reducing agent, Poly acts as dispersing agent, and DEG acts as reaction medium. We studied the effect of size on antioxidant property of Cu particles, and determined the sintering temperature of Cu nanoparticles. In addition, we also measured the resistivity of the sintered copper block.In this paper, we modified the polyol method, and synthesized pure Cu nanoparticles of good antioxidant property. According to the FT-IR analysis, the surfaces of Cu nanoparticles are coated with polyvinylpyrrolidone. We studied the effect of reaction parameters on preparation of Cu nanoparticles. According to the experimental phenomenon, we assumed that the polyvinylpyrrolidone had a great influence on the reaction, when its molar weight was bigger, the smaller the particle size. The greater the amount, the better the dispersibility of the Cu nanoparticles; the reducing agent also had a significant effect on the reaction, when the experimental amount increased within a certain range, the particles size would get smaller. At the same time, the Cu nanoparticles were in different morphology when the reaction was shorter than lhour.Ultimately, we determined the optimal synthesis condition of Cu nanoparticles:the reaction time was lhour, the molar mass of polyvinylpyrrolidone was58000gmol-1, the experimental amount was3g the mass ratio of copper sulfate pentahydrate and sodium hypophosphite was5:12.We studied the effect of size on antioxidant property of Cu nanoparticles, as a result, the larger the size, the better the antioxidant property.