Among metals, the conductivity of copper powder conductive paste is second only to silver, with high bonding strength and low cost, which makes the advantages of copper powder conductive paste particularly prominent. So, what is the performance of copper powder conductive paste in all aspects of application?

1. The conductivity of copper powder conductive paste

Copper powder conductive paste requires low resistivity and good electrical stability during use. It is generally believed that the choice of resin, the particle size, morphology and content of the copper powder, and the choice of additives have a great influence on the conductivity of the copper powder conductive paste. In order to improve the conductivity of copper powder conductive paste, irregular (flaky or fibrous) copper powder should be used. The content of copper powder should be controlled between 54% and 60%. At the same time, a small amount of conductivity promoter should be added to the conductive paste. It also improves the shrinkage of the polymer matrix.

2. Shear strength performance of copper powder conductive paste

The bonding strength of the copper powder conductive paste depends on the internal stress on the resin matrix and the interface. Wang Jihu and others prepared a copper powder conductive paste adhesive with a thermosetting acrylate resin as the matrix and copper powder with a special surface treatment. When copper powder is added to the adhesive, the T-shaped peel strength of the copper powder conductive paste becomes smaller. With the increase of the number of copper powder meshes, the peel strength decreases, but the change is not significant; the shear strength of the copper powder conductive paste is larger than that of the blank, and as the number of copper powder meshes increases, the shear strength also increases.

Third, the aging performance of copper powder conductive paste

Aging performance is an important parameter that affects the performance of copper powder conductive paste. The main reasons for the aging of copper powder conductive paste are: copper powder oxidation and adhesive aging. Accelerated aging experiment is an indispensable important work in the design and production of electronic connection materials. In order to facilitate comparison, it is usually necessary to design a special device to test several connection methods at the same time. Generally speaking, if the connection strength and resistivity before and after the accelerated aging test are less than 20%, the copper powder conductive paste can be considered stable.

Fourth, the connection strength performance of copper powder conductive paste

The connection strength of the copper powder conductive paste includes the connection strength between the adhesive molecules after curing and the connection strength between the adhesive molecules and the surface of the connected object. The copper powder conductive paste is required to have good connection strength and toughness after curing. The connection strength is an important factor affecting the connection reliability of the copper powder conductive paste.

Five. contact resistance stability of copper powder conductive paste

The contact resistance when the copper powder conductive paste is connected to the non-precious metal surface is an important factor affecting the stability of the copper powder conductive paste. The International Manufacturing Science Center (NCMS) has formulated technical standards for commercial surface mount conductive pastes, including volume resistivity not exceeding 1×10–3 Ω·cm, contact resistance at 500 h, 85°C, and RH: 85% change No more than 20%, PLCC (plastic lead chip package) carrier drop impact test can withstand 6 times from a height of 1.524 m.

Sixth, the oxidation resistance of copper powder conductive paste

In the research of copper powder conductive paste, the main reason for its application is that the copper powder conductive paste is easily oxidized during the high temperature curing process, and the conductive paste is used for a long time, especially in a humid environment. The copper powder is slowly oxidized into copper oxide and cuprous oxide, which increases the resistivity of the copper powder conductive paste and reduces the conductivity. At present, domestic and foreign research institutions mainly use reduction, coating, electroless plating and other methods to modify the surface of copper powder, and they have achieved good results.

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