What are the Characteristics of No-Clean Flux_Shenzhen Fitech



What are the Characteristics of No-Clean Flux_Shenzhen Fitech

In semiconductor soldering, solder paste is commonly used. Solder paste consists of alloy solder powder and flux. For high-reliability packaging, flux selection is critical. Regular rosin solder paste fluxes produce corrosive residues after soldering. Corrosive residues will continuously affect the reliability of solder joints. Therefore, it is usually necessary to clean the PCBs and remove the flux residues after the soldering. However, the cleaning process for large-scale cleaning is cumbersome and time-consuming and is prone to incomplete cleaning. Is there a type of solder paste flux free from cleaning?


The packaging industry is currently concerned about the halogen content in solder paste fluxes. The halogen representatives are chlorine and bromine. The halogen-containing solder flux has good activity and is better in soldering. However, due to the high amount of residual halogen ions, the electrical performance of solder joints is reduced. The development of no-clean fluxes has been accelerated as traditional cleaning agents such as chlorofluorocarbons and ozone-depleting solvents have been banned. 


No-Clean Flux Features

The no-clean solder paste flux has a similar function to the conventional solder flux, which can reduce the tension between the solder powder and the soldering surface by removing the oxide layer of the copper pads. No-clean flux means that the residue after soldering is tiny and harmless, the electrical properties of the solder joint are good, and the solder flux is unnecessary to clean under certain application environments. No-clean flux has less solid content, probably less than 5% of the total solder paste flux.


No-clean flux components are mainly composed of organic solvents, organic acid activators, cosolvents, film-forming agents, etc. No-clean and traditional rosin fluxes differ in the base materials and active agent formulations. No-clean flux can be alcohol-based or water-based, using fatty surfactants or aromatic non-ionic surfactants. Alcohol-based no-clean flux evaporates quickly during soldering, which can reduce spatter. The no-clean solder paste flux starts functioning in the soldering preheating stage and is most active in the reflow stage. The solder flux is mostly consumed eventually. There is only a trace amount of residue left on the PCB after soldering.


No-Clean Flux Concerns

No-clean flux is not suitable for all scenarios. For some components with high precision and high reliability requirements, such as medical equipment and aerospace equipment, more experiments are still needed to verify the feasibility of no-clean flux. Even a slight decrease in reliability can cause huge losses. Before sufficient verification, the PCBs still need to be cleaned.


Fitech can produce high-reliability solder pastes with no-clean formulations, which have good wettability, less residue formation, and outstanding anti-slump performance. Welcome to inquire about more information.


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