The principle of methylcellulose crystallinity and its application in copper-based electronic pastes

As a macromolecular substance, cellulose is susceptible to the formation of interaction forces between its chains, which ultimately result in the generation of crystalline regions. In this paper, the reversible dehydrogenation reaction of ascorbic acid is employed, whereby the combination of dehydroascorbic acid and the hydroxyl group on the molecular chain of methylcellulose forms hydrogen bonding with the purpose of occupying the hydroxyl group on the molecular chain and inhibiting the formation of hydrogen bonding between the chains, thus eliminating the crystalline zone of methylcellulose. The alteration of hydrogen bonding and the elimination of the crystalline region were identified through the utilization of Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Concurrently, a copper paste is formulated. The addition of copper results in the intensification of the oxidation of ascorbic acid at temperatures in the range of 200 °C. This leads to the formation of oxalic acid, which subsequently forms copper oxalate with copper at high temperatures. This process then enters the ascorbic acid colloid, forming a conductive channel. In accordance with the principles, a low-temperature sintered copper paste was devised and manufactured, exhibiting a high viscosity recovery rate (75.8%), high adhesion, low resistivity (4.2*10⁻⁶Ω*cm), and objective aspect ratio (0.28) after screen printing.