Studying On Preparation And Properties Of Halogen-free,Rosin-free,Antibacterial And No-clean Flux For Lead-free Solder

In the electronics industry, the Sn-Pb solder has been gradually replaced by the lead-free solder, and the associated flux needs to be done for further improvement. In this thesis, a kind of the water base halogen-free rosin-free antibacterial and the no-clean flux for Sn-3.0Ag-0.5Cu lead-free solders was developed by the orthogonal test and progressive optimization method, and the performance of the samples was tested by the testing method of industry criterion of SJ/T11273-2002No-clean Liquid Flux and SJ/T11389-2009Lead-free Soldering Flux. The outcome indicated that, this flux has a good physical stability, rosin-free, halogen-free, low solids content. It will not mildew, and which expansion rate reached76.64%, non-corrosive, non-clean, with good performance. It is a green and environment friendly flux which can meet all of the requirements of the lead-free solders.In this experiment, deionized water was chosed as a solvent. When choosing organic acid activator, we need to consider the solubility of the organic acids. The selected several of organic acids can be all dissolved with the help of the ether cosolvent. At the same time, the best acids were selected, which have the strongest wetting power. The good soldering activity showed that the selected succinic acid, adipic acid and hydroxy carboxylic acid compound A mixed as activators, optimized by orthogonal test. The good results of soluting and soldering were showed when alcohol co-solvent were mixed. Specially, glycerol, C alcohol and acetamide perform better than others, so they were chosed. Larger surface tension of the solvent water, the non-ionic surfactants sucrose ester and D ester played the better role of surface tension reduction for fluxes. T-butyl hydroquinone and natural antibacterial agent E were added, which effectively inhibited the growth of bacteria and fungi and extend the shelf life of the flux.A kind of the halogen-free rosin-free antibacterial and no-clean flux was developed in this research, following the requirment of practical industrial applications. A formula was designed and optimized, including activator, latent solvent, surfactant, and so on. By comparing with two kind commercial fluxes, the main properties of the self-made flux were tested and evaluated. It was found that the self-made flux had a spreading rate of76.64%, regular and bright solder joint morphology, less residues. For demanding electronic products can be exempted from cleaning. And the self-made flux had excellent performance on soldering, non-toxic, non-halogen, non-rosin, environmental protection, low cost than the commercial flux.