Tin-radical welding flux/copper particle composite welding flux capable of forming high-temperature welding spots rapidly at low temperature

Abstract

The invention provides a tin-radical welding flux / copper particle composite welding flux capable of forming high-temperature welding spots rapidly at a low temperature. The tin-radical welding flux / copper-particle composite welding flux is composed of tin-radical welding flux powder, copper particle powder and welding paste, wherein the weight ratio of the tin-radical welding flux powder and the copper-particle powder lies between 5:2 and 2:3, the weight ratio of the remaining welding paste is 4%-20%, the particle size of the tin-radical welding flux powder is preferentially from 5 micrometers to 60 micrometers, and the particle size of the copper particle powder is from 0.1 micrometer to 10 micrometers. By means of the tin-radical welding flux / copper particle composite welding flux, the characteristics of a low melting point of the tin-radical welding flux and good wetting reaction of tin-copper are utilized, the high-melting intermetallic compound (IMC) interconnection welding spots can be formed within a short moment at the low temperature and without any pressure, and the tin-radical welding flux / copper particle composite welding flux is applicable to leading wire interconnection of electronic devices when a high temperature is caused during the service process or which performs the service at the high temperature. According to the tin-radical welding flux / copper particle composite welding flux capable of forming the high-temperature welding spots rapidly at the low temperature, the technology is simple, the cost is low, the practicability is great, and the problems of high cost, long welding time and high welding temperatures in existing chip packaging materials are solved.

Description

technical field [0001] The invention belongs to the technical field of lead-free solder alloy and electronic packaging and interconnection, in particular to a tin-based solder / copper particle composite solder capable of rapidly forming high-temperature solder joints at low temperature and a preparation method thereof. Background technique [0002] At present, the development of the electronics industry has put forward the requirements of multi-function, high performance and high density for microelectronic systems, and the problem of heat resistance has become increasingly prominent while interconnection solder joints continue to be miniaturized. For some high-power devices (such as high-power LEDs, power SiC chips, automotive electronic devices, etc.), the internal chip-level interconnect solder joints need to withstand high temperatures above 200-300°C when they are working, which exceeds most of the high-power devices. The melting point of lead-free solder (around 210-220...

AI Technical Summary

Problems solved by technology

However, the biggest problem with the current TLP process is that the formation of full IMC solder joints is too slow, and the tin-based solder layer can only be completely transformed into a compound within the normal soldering process range (260-280 ° C, a few minutes) if the size of the tin-based solder layer is below 2 μm.

For the vast majority of chip-level solder joints at present, the height is still in the scale range of tens to hundreds of microns. Li et al. [Acta Materialia 59(2011) 1198–1211] pointed out that for Cu / Sn / The Cu structure needs to be reacted at a temperature of 300°C for 1 hour to completely transform into a high melting point IMC solder joint structure. Such a reaction efficiency is difficult to apply to actual production

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