OSPI 3311

alcohol-based soldering flux

replaced by

OSPI 3311 been replaced by .

OSPI 3311 10L angle

Suitable for

  • OSP is an Organic Surface Protection used in PCB manufacturing to preserve the solderability of the PCB board during storage and in between the different soldering processes. It is the most economical surface protection. The main limitation is that a lot of OSPs will degrade after that they have seen a lead-free reflow profile. This can result in reduced through hole wetting of the through hole components in wave and selective soldering.The time between the reflow soldering process and the wave or selective soldering process is important in this matter. Some OSPs show signs of degradiation already 4 hours after  the lead-free reflow soldering process. Low melting point solder pastes need lower temperatures in the reflow soldering process and substiantially reduce the degradation of most OSPs.  A soldering flux that has been specifically designed to improve wetting on OSP surfaces that have seen a lead-free reflow profile, like OSPI 3311M can compensate for the degradation of the OSP coating and provide acceptable soldering results.

  • Wave soldering is a bulk soldering process used in electronics manufacturing to connect electronic components to a PCB board. The process is typically used for through hole components but can also be used for soldering of some SMD (Suface Mount Device) components that are glued with an SMT (Surface Mount Technology) adhesive to the bottom side of the PCB before passing through the wave soldering process. The wave soldering process comprises three main steps : Fluxing, preheating and soldering. A conveyor transports the PCBs through the machine. The PCBs can be mounted in a frame to avoid adjusting the conveyor width for every different PCB.  Fluxing is usually done by means of a spray fluxer but also foam fluxing and jet fluxing are possible. The liquid flux is applied from the bottomside of the PCB on the surface and in the trough holes. The purpose of the flux is to deoxydize the solderable surfaces of the PCB and components and allow the liquid soldering alloy to make an intermetallic connection with those surfaces resulting in a solder joint.   The preheating has three main functions. The solvent of the flux needs to be evaporated as it loses its function once its has been applied and it can lead to soldering defects like briding and solder balling when it contacts the solder wave in a liquid state. Water based fluxes in general need more preheating to evaporate than alcohol based fluxes. The second function of the preheating is to limit the thermal shock when the PCB contacts with the liquid solder of the solder wave. This can be important for some SMD components and PCB materials. The third function of the preheating is to promote through hole wetting of the solder. Because of the temperature difference between the PCB board and the liquid solder, the liquid solder will be cooled down when going up the through hole. Thermally heavy boards and components can draw away so much heat from the liquid solder that it is cooled down to the solidification point where it freezes before it gets to the top. This is a typical problem when using Sn(Ag)Cu alloys. A good preheating limits the temperature difference between PCB board and liquid solder and hence reduces the cool down of the liquid solder when going up the through hole. This gives a better chance that the  liquid solder will reach the top of the through hole.  In a third step the PCB board is passed over a solder wave. A bath filled with a soldering alloy is heated up to soldering temperature. This soldering temperature depends on the used soldering alloy. The liquid alloy is pumped through channels up into a wave former. There are several types of wave formers. A traditional setup is a chip wave combined with a laminar main wave. The chip wave jets solder in the direction of the PCB movement and allows to solder the back side of SMD components that are shielded of wave contact in the laminar wave by the body of the component itself is. The laminar main wave flows to the front but the adjustable back plate is positioned like this that the board will push the wave into a back flow. This will avoid the PCB being dragged through the reaction products of the soldering. A wave former that is gaining popularity is the Wörthmann-wave that combines the function of the chip wave and the main wave in one wave. This wave is more sensitive to the correct setting and bridging. Because of the fact that lead-free soldering alloys need high working temperatures and tend to oxydise quite strongly, a lot of wave soldering processes are done in a nitrogen atmosphere. A new market tendency and the considered by some as the future of soldering is the use of a low melting point alloy like e.g. LMPA-Q. LMPA-Q needs less temperature and reduces oxydation. It also has some cost related benefits like reduced electricity consumption, reduced wear ot of carriers and no need for nitrogen. It also reduces the thermal impact on electronic components and PCB materials.

  • Selective soldering is a soldering technology in electronics manufacturing, typically used for PCB designs with mainly SMD (Surface Mount Device) components for reflow soldering and only a few through hole components that cannot pass through the reflow soldering process. These are usually thermally heavy mass components like e.g. big transfo's or thermally sensitive components like e.g. film capacitors, displays,  connectors with sensitive plastic bodies, relays, etc... The selective soldering process allows to solder these through hole components without protecting or affecting the SMD components on the bottom side of the PCB.  The selective soldering process is very flexible as the parameters can be programmed for each solder joint separately. The main limitation of the process however is the throughput or the production capacity. This can be considerately improved when using a low melting point alloy that allows for faster soldering speeds increasing production capacity up to 100% (double). The process starts with the application of a liquid flux that will deoxydize the surfaces to be soldered. This flux is applied by a micro jet or drop jet fluxer that shoots little drops. The correct calibration and programming of this fluxer is essential to get good soldering results. A common mistake is that flux is applied outside of the contact area of the soldering nozzle. This flux will remain as an unconsumed flux residue. For some fluxes and sensitive electronic circuits this can lead to increased leakage currents and failure in the field. It is advisable to use fluxes that are specifically designed for selective soldering and that are absolutely halogen free. The IPC classification for fluxes allows up to 500ppm of halogens for the lowest activitiona class but also these 500ppm can be critical, so absolutely halogen free is the key word. The next step in the process is preheating. This process step evaporates the solvents of the flux and provides heat to support good through hole wetting of the solder. Soldering is a thermal process and a certain amount of heat is needed to make a solder joint. This heat is needed from the bottom as well as from the top of the through hole component to be soldered. This heat can be provided by the preheating and by the liquid soldering alloy. Some basic machines do not have preheating, they will have to apply all heat through the liquid soldering alloy and in general they use higher temperatures for soldering. A preheating unit is usually a short wave IR (infrared) unit that applies the heat from the bottom side of the PCB. In most cases, the time and power of the preheating can be programmed. For thermally heavy boards and applications, top side preheatings exist. Usually they are hot air (convection) units where the teperature of the air can be programmed. When using this unit, it is important to know if there are any temperature sensitive components on the top side of the board that might be affected by this preheating.  Several systems for soldering exist. The one where the PCB board is standing still and only the soldering nozzle is moving is definitely preferred as all G-forces should be avoided when the solder solidifies. In the soldering step, a liquid soldering alloy is pumped through a soldering nozzle.There are different nozzle sizes and shapes available, wide nozzles, small nozzles, long nozzles and short nozzles.  Depending on the components to be soldered, one is preferred to another. In general wider nozzles and shorter nozzles give better heat transfer and are preferred. Smaller and longer nozzles can be used for situations with limited accessibility. Wettable nozzless are preferred to non wettable nozzles as they give a much more uniform flowing of the solder and more stable soldering results. Nitrogen flooding of the nozzle is advisable to have a stable flowing of the solder. The nitrogen is preferrably preheated because when not, it will cool down the solder and the PCB. The optimisation of the soldering program is essential for optimisation of the throughput/capacity of the selective soldering machine. This will focus on finding the minimal times and maximal speeds that give good through hole wetting in combination with no bridging.

Key advantages

  • For OSP surface finishes