Fabrication of Novel Ag Flake Composite Films Using a CMC/PEI Cross-Linking Process

The multifunctional properties of cross-liked carboxymethlycellulose (CMC) and polyethyleneimine (PEI) films with varied CMC:PEI ratios and Ag flake sizes were studied. Both the CMC and PEI were cross-linked through a sonication process to achieve dispersive equilibrium. Fourier-transform infrared spectroscopy (FT-IR) was used to identify the functional groups in the sample material, with thermogravimetric analysis and differential scanning calorimetry used to investigate the overall thermal behavior of the CMC–PEI cross-linked films. Thermal diffusivity and thermal conductivity were also analyzed using laser flash analysis. To analyze the effects of Ag flakes as a filler material, the distribution of the Ag flakes within the film was determined using scanning electron microscopy. The thermal conductivity and resistance of the CMC films increased when cross-linked with 20% PEI. The electrical and thermal properties of the films also improved with the addition of Ag flakes. Graphic Abstract The multifunctional properties of cross-liked carboxymethlycellulose and polyethyleneimine films with varied CMC:PEI ratios and Ag flake sizes were studied. The thermal, electrical and mechanical properties of solder joints were investigated by using various kinds of tests.