Properties investigation on isotropical conductive adhesives filled with silver coated carbon nanotubes

In this study, chemical plating method was used to prepare silver coated carbon nanotubes (SCCNT). Fundamental materials characterizations including X-ray diffraction and transmission electro microscopy (TEM) were conducted on these nanotubes. Two kinds of isotropical conductive adhesives (ICA) were developed by using multi-walled carbon nanotubes (CNT), SCCNT as conductive fillers, respectively. The electrical, mechanical and aging properties of above ICAs were investigated and compared with that of conventional ICA filled with 1 μm average-sized Ag particles. The results indicated that the percolation threshold of bulk resistivity reaches 2.4 × 10−3 Ω cm for ICA filled with 31% CNT and the shear strength reaches the maximum value for ICA filled with 23% CNT. At the same filler volume content of 28%, the ICAs filled with SCCNT shows the lowest conductive resistivity of 2.2 × 10−4 Ω cm and the ICAs filled with both CNT and SCCNT exhibit higher shear strength (19.6 MPa). The testing results of aging properties under conditions of 85 °C, RH85% for 1000 h showed that the shifts of both bulk resistivity and shear strength did not exceed 15% for the ICAs filled with both CNT and SCCNT, while the shifts of conductive resistivity and shear strength were 200% and 35%, respectively, for ICA filled with micro-sized Ag particles.