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IEI | Laboratory-Scale Fluxless Soldering System | |
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Solder flux is an organic material that is applied to solder joints before reflow. It is used to dissolve surface oxides that prevent the solder from flowing smoothly. All fluxes leave some residue. Fluxless soldering is a pretreatment that allows reliable solder joining without flux. It is a zero residue process. The pretreatment is done prior to reflow and consists of exposing the solder-coated parts to a gas phase process that converts the surface oxides to a form that breaks-up easily during when the solder liquifies. The process has been used for flip chip and ball-grid assembly as well as for assembling micro-optical components. IEI has constructed a number of fluxless tools ranging in size from large continuous belt systems to small discrete cycle systems such as the system shown here.
IEI is licensed to provide two types of fluxless systems. Both types function by fluorinating the interface between the surface oxides and the underlying metal. The fluorination is very effective in reducing the bonding in this region. The first, called Plasma Assisted Dry Soldering (PADS), exposes the parts to the effluent of a low pressure discharge where the fluorinating source is effectively the fluorine atoms produced in the discharge. The second, called Gaseous Soldering Technology (GST), produces the gas phase fluorination source by thermal decomposition of an easily handled solid material Advanced Manufacturing Technologies, LLC. In either case the pretreatment is effective in promoting solderability for a number of months if the treated parts are kept dry (e.g. stored in a container with a desiccant). |
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