Nanometer silver powder is added in the flake silver powder on the influence of conductive colloid volume resistivity
1. With high density and high integration of the rapid development of the miniaturization of electronic components, miniaturization and the printed circuit board, conductive adhesives because the process is simple, easy operation, high line resolution and less environmental pollution and other advantages become Alternative tin solder, an ideal choice for conductive connection. Conductive paste made of conductive filler, gum base, diluents, tougheners and other additives, wherein the conductive filler of the volume resistivity of the conductive adhesive plays an important role.
2. In practice, a good contact with the conductive filler in order to form a conductive path, in order to achieve this, people try to add a flake, needle or fibrous conductive filler. However, under a transmission electron microscopy revealed: complete conductive gel particles and particle contact and a continuous linear conductive paths there are actually very few particles more than a small gap, this part of the particle is to “tunneling” to obtain a conductive a. Order by “tunneling” to get better conductivity, the distance between the particles must be less than 10 nm, we therefore had to add nano silver in silver flake ideas and research.
3. The results, at a 5% mix of nano silver powder, nanometer silver powder evenly dispersed between silver flake play a very good connection, and improve the conductivity of silver; and the addition of 10% nanometer silver powder mixed powder, many nano-silver reunited increase body resistance between silver.
4. Adding different content of nano-silver powder into flake silver made into conductive adhesive formulated after conducting were studied. Nano silver powder were added at 5% and 10% added to the silver flake, and made of different conductive plastic silver content measured volume resistivity. The results obtained by experimental comparison: 5% nano silver powder mixing ratio of 10% of the mixed powder dubbed nano-silver conductive paste low volume resistivity, good conductivity. The possible reasons are: flow through when approaching a threshold, silver flake still not well connected, adding a small amount of nano powders can help build a conductive network to reduce the volume resistivity; once form a connection, the nano silver particles will increase between the contact resistance.
5. Add different proportions of nano silver in silver flake will change the conductivity thus obtained conductive paste, nanometer silver powder is added generally increases the volume resistivity of the conductive adhesive. However, near the “cross-flow threshold”, the amount of nano-silver is added to form a conductive path; it can reduce the volume resistivity of the conductive adhesive. This study shows that when nano-silver increased amount of 5%, the volume resistivity decreased obviously, silver content of 75% volume resistivity as low as 1.6 × 10-4Ω • cm.
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