Heat conducting silver paste and preparation method thereof

Abstract

The invention discloses a heat conducting silver paste comprising the following components: silver powder, carbon nanotubes, bisphenol F epoxy resin and a curing agent, wherein the silver powder is subjected to heat treatment, so that surface-anchored -SH is obtained; and the carbon nanotubes are treated by a plasma treatment machine, so that a plurality of -COOHs are formed on the surfaces of thecarbon nanotubes. The invention further provides a preparation method of the heat conducting silver paste. A sulfur element in -SH in a compound in the scheme of the invention can form a chemical bond with silver atoms in the silver powder under a certain state, and the residual -NH2 functional groups in the compound can be combined with -COOHs on the carbon nanotubes to form physical bonding insilver paste processing, transportation and curing processes, in other words, a gap among the silver powder is filled with the carbon nanotubes which also interact with the silver powder, so that thedistance among the silver powder is shortened, the overlapping is more perfect, and the heat conducting efficiency is increased.

Description

technical field [0001] The invention relates to the technical field of composition preparation, in particular to a highly thermally conductive silver paste used for connecting high-power LEDs and solar cells. Background technique [0002] The silver paste used for electrical interconnection or circuit formation in the market generally adopts epoxy resin system or oxide system. The epoxy resin system is to add silver powder to epoxy resin and curing agent. The oxide system is oxidized at several low melting points. Nano-scale silver powder is added to the product, the former is solidified at not lower than 100°C to form a product, and the latter needs to be sintered at a high temperature. [0003] The disadvantage of the silver paste of the oxide system is that the sintering temperature is very high, the application area is narrow, and the advantage is also obvious: high conductivity. Patent CN1870310 discloses a method of packaging and connecting high-power LEDs by low-temp...

AI Technical Summary

Problems solved by technology

The method adopts nano-silver solder paste prepared by uniformly mixing nano-silver particles with a particle size of less than 100nm, dispersant fish oil, binder α-terpineol and solvent acetone with the assistance of an ultrasonic water bath, and sintering at low temperature to package and connect high-power light-emitting diodes. , the advantage is that it improves the shortcomings of LED packaging materials in terms of electrical conductivity, thermal conductivity, bonding strength, and high temperature resistance. However, the disadvantages are also obvious. The silver glue of this patent must be heated to 290 ° C to complete the sintering. The sintering temperature On the high side, it cannot be used in situations where lower temperature operation is required

On the other hand, after the silver paste of the epoxy resin system is cured, the silver powder is connected together by the epoxy resin. The advantage is that the operating temperature is low, and the disadvantage is that the thermal conductivity is low and cannot be used in high-power occasions; The lap joint between them is achieved when the silver paste shrinks when it solidifies, and the silver powder is pulled closer by the epoxy molecules. The thermal conduction channel formed by this lap joint alone cannot meet the high-power market demand.