Surface treatment is a commonly used method to improve the oxidation resistance of copper powder and enhance the performance of conductive paste. One treatment method is to deposit or coat a layer of gold, silver, nickel and other metals with more stable chemical properties on the surface of copper powder. Among them, silver is the most common coating material; another common treatment method is to treat with organic acid Copper powder generates copper carboxylate, which can protect the copper powder.
Lactic acid and DEAPD (3-diethylamino-1, 2-propanediol) were selected to treat the surface of copper powder separately and together. In order to further explore the effect of surface treatment on the performance of copper conductive paste, we mixed copper powder with different surface treatments and ERL 4221-acid anhydride matrix to prepare a conductive paste with a filling volume of 75%. After curing for 1 hour, the volume resistivity results are shown in the figure. Copper lactate can be adsorbed on the surface of copper powder to play a protective role, and the nano-copper produced by thermal decomposition is also conducive to the improvement of conductivity. DEAPD can form coordination with the surface of copper powder, and its dendritic structure can effectively block oxygen and prevent the oxidation of copper powder. When copper lactate and DEAPD exist at the same time, it can play a double protective effect on copper powder.
Anti-aging performance is also one of the important properties of conductive paste, which directly affects the reliability of conductive paste performance in use. We conducted preliminary aging tests on conductive pastes prepared from copper powders with different treatments to explore the performance stability of conductive pastes at higher temperatures. The test conditions are air atmosphere, aging at 85°C for 168h, and measuring the resistivity of the conductive paste every 24h. It can be found that the resistivity of the conductive paste prepared from the copper powder without any treatment increases rapidly with the increase of aging time, and the resistivity of the conductive paste obtained by the treatment method can maintain good stability.
Lactic acid and DEAPD are used to treat the surface of copper powder at the same time, which protects the conductive filler copper powder during the preparation of conductive paste, conductive paste performance, use and storage, and effectively improves the oxidation resistance of conductive filler copper powder And the electrical properties and anti-aging properties of copper conductive paste.