Gas Preparation Of Ultrafine Tin-based Lead-free Solder Powder

Tin-based lead-free solder is the ideal alternative to lead solder materials, with the rapid development of electronic industry, high-performance tin-based conductive adhesive, solder paste, especially the development of nano-scale electronic packaging has become the major issue of electronic field. Ultrafine powder tin-based lead-free solder paste such as conductive adhesives of raw materials, their quality and yield have become key issues in this area. This study is the use of plasma to prepare Sn-Zn-Bi lead-free solder alloy powder.At the present time, there are many methods of preparation for metal powder. On the purpose of achieving manufacturing from the functional powder, the process of simple and controllable, variety of factors in the process of preparation methods were discussed. Especially, in plasma arc method, the current strength, Ar flow, air traffic and other parameters on the particle size, powder resistance and yield were discussed.Test results and process parameters were optimized and conduct comprehensively.In this study, Sn, Zn, Bi three kinds of pure metal powders were studied, the results summarized from the plasma Ultrafine Metal Powder Process methods and empirical parameters. This parameters maded for the further using to prepare more complex alloy solder powder. At this point, not only to ensure the pre-request, we should also address the key technical about alloy fractionation. Here, this study proposed innovative solution. Using timely and quantitative methods to feed, making sure the gasification of alloy in the context of the minimum heat capacity, guaranteed the gasification with high evaporation rates and evaporation rate, to realize the feeding amount correspond with the gasification capacity, strengthening the gasification efficiency and prevent the alloy fractionation. The experimental sample used X-ray diffraction (XRD), transmission electron microscopy (TEM), DTA - Analysis (DSC) and other modern detection methods to characterize the powder. The results show that:in the Ar flow rate 12L/min, to the feeding 5g/min, pressure is 2100mm and the current intensity of 260A,the powder has good dispersion,particle size distribution, around 100nm, high purity, and segregation is not obvious.In this method, it achieve continuous reaction and preparation in chamber by this special feeding method. Besides, in preparation of the alloy composite powder, the metal fractionation and segregation issues are not produced. Finished solder powder will be able to collect by one Step reaction.It provided a new way for industrial gasification.