Many RMA fluxes pass SIR testing as a NC flux. IPC classification is usually ROL0, ROL1, ROM0, Most RMA flux is fairly low in activity and best suited toĮasily solderable surfaces. Rosin mildly activated (RMA) flux consists of rosin, solvent, and a smallĪmount of activator.
Some,īut not all, NC fluxes are more difficult to remove than RMA fluxes. Residue may be removed with an appropriate solvent. Hard, non-corrosive, non-conductive, and designed to be left on many types IPC classification is usually ROL0 or ROL1. NCįlux typically has low-to-moderate activity and is suited to easily solderable No clean flux consists of rosin, solvent, and a small amount of activator. Is hard, non-corrosive, non-conductive, and may be left on. Suitable only for easy-to-solder surfaces. Rosin flux consists of rosin and solvent. Note overlap of activity levels between flux groups. FLUX COMPARISONįlux Comparison chart shows relative activity ranges of each flux category. Each isĪvailable with a variety of activity levels, physical qualities of their residue, andĬleaning methods required. There are five main categories in QQ-S-571E. POWDER SIZEįlux categories are defned by Military Specification QQ-S-571E as well as the Using a smaller powder will just cost more. Using too large a powder will cause printing and dispensing difficulties,Ĭompromising quality. If the feature is smaller, the application requires the next smaller powder size. Dimensions listed for gullwing, square/circle, and dispenseĭot sizes represent the smallest feature recommended for that size powder. (Figure 2) cross-references particle size to typical printing and dispensing Having selected the best alloy, particle size is next. Process, the peak temperature of the later operation needs to be below the To retain physical integrity during a later operation, such as a second reflow While wetting begins at the solidus temperature, best wetting is achieved atĪ peak temperature 15º C or more above the liquidus.
Sometimes this is due to the product falling under the RoHS (Restriction of Hazardous Substances) directive and sometimes it is a corporate directive. Many applications have a requirement for use of lead-free solder alloy. What type/size does the power need to be for the smallest feature.Is there a reflow temperature requirement or limitation?.
When choosing a solder alloy, there are a few questions that need It is always worth a call to your Nordson EFD solder sales specialist to review requirements to ensure you are using the best solder paste for the job. There are additional details of alloy and flux performance not covered that can be very important in the selection process. We have a full range of soldering and brazing fluxes including the popular fluxes.Solder Selection Guide This guide covers the most significant steps in selecting a solder paste. It was ideal in that it was non-corrosive and non-conductive at normal temperatures but became mildly reactive (corrosive) at the elevated soldering temperatures. Some fluxes go beyond the simple prevention of oxidation and also provide some form of chemical cleaning (corrosion).įor many years, the most common type of flux used in electronics (soft soldering) was rosin-based, using the rosin from selected pine trees. The impurities can be removed by mechanical cleaning or by chemical means, but the elevated temperatures required to melt the filler metal (the solder) encourages the work piece (and the solder) to re-oxidize. This effect is accelerated as the soldering temperatures increase and can completely prevent the solder from joining to the work piece. The main obstacles to a successful solder joint is an impurity at the site of the joint consisting of dirt, oils or oxidation. The purpose of flux is to facilitate the soldering process.