IF 8300

Low residue tacky gel flux

Interflux® IF 8300 is a no-clean, halide-free tacky gel flux suitable for reballing and BGA rework.

IF 8300 11

Suitable for

  • Stencil printing is the most used method to apply solder paste on the pads of a PCB (Printed Circuit Board) in the SMT (Surface Mount Technology) assembly line in electronics manufacturing. After stencil printing, SMD (Surface Mount Device) components are placed with their solderable contacts on the solder paste and the PCB is transported through a reflow oven where the components are soldered to the PCB board. Stencil printing can also be used to apply solder paste in trough holes for the Pin in Paste (PiP, intrusive reflow) technology that is meant to solder through hole components in the reflow soldering process . Stencil printing can also be used to apply SMT adhesive (glue) to the PCB board. SMD components  are placed with their body on the glue that will be cured in a reflow oven. After that, the SMD components that are glued to the PCB board will be soldered in a wave soldering process.  The PCB board is pressed onto a stencil that has apertures where the solder paste needs to be deposited. A volume of solder paste is present on the stencil. A squeegee is lowered onto the stencil with a certain pressure. The squeegee moves over the stencil with a certain printing speed. This will make the solder paste roll into the apertures. The printing speed can be determined by the desired throughput, typical for high volume productions but can be limited by the used solder paste. This speed can vary from 20-150 mm/s. Once the desired speed has been established, a printing pressure will have to be determined for that printing speed. Higher speeds require higher pressures.  The correct printing pressure is the minimum pressure needed to get a clean stencil after printing, meaning all excessive solder paste  has been removed by the squeegee.  The board is moved away vertically from the stencil, the solder paste releases from the stencil and pads of the PCB have solder paste deposits. The goal is to have a well defined printing result where all solder paste has realeased from the stencil and no solderpaste has been pressed between the stencil and the PCB board. The release of the solder paste obviously is more difficult for smaller apertures and thicker stencils. Some design rules say that the ratio of the surface of the aperture to the surface of the sides ('walls') of the aperture  is preferrably not smaller than 0,6.  The quality of the stencil is a major parameter in good paste release. Rough sides are more likely to adhere solder paste. Different types of stencils exist. The most popular is the stainless steel stencil with laser cut apertures that are smoothened afterwards by a chemical process. Sometimes they are treated with a coating for better paste release. The main reasons for solder paste being pressed in between the stencil and the PCB board is bad sealing between board and stencil or too high printing pressure for the used printing speed. This can lead to solder balling or bridging after reflow.  Some printing machines have an automated under stencil cleaning unit that can be programmed to clean the stencil after so many prints. This will facilitate a stable printing result. It is advisable not to use IPA based or water based cleaning liquids in these units as they may affect the solder paste stability. The use of products that have been specifically designed for that purpose is advisable. The stability of the solder paste on the stencil, meaning how well that the solder paste keeps its printing properties over time, is also a parameter for a stable printing process. Some printing machine have integrated AOI (Automated Optical Inspection) that will check the printing result and give an alarm if it deviates from the programmed desired values. This will help to avoid electronic units being produced with solder joints that are not according good standard.

  • Dispensing is a technology used in electronics manufacturing to apply solder paste (or an adhesive) from a syringe to a PCB (Printed Circuit Board). Dispensing is a more flexible way to apply solder paste than standard stencil printing because it allows to selectively apply solder paste with the presence of pre-assembled components on the surface. However dispensing is a much slower process than stencil printing and not suitable for high volume productions. That's why it is mostly used to add extra solder paste in an SMT (Surface Mount Technology) assembly line but also for rework and repair and in prototyping. Dispensing can be done manually or automatically.  In rework and repair this is usually done manually with a system that applies pressurised air to the plunger of the syringe and the solder paste is pushed out through a needle. But it can also be done by hand with a manual plunger.  In automated processes like in a stand alone dispenser in a SMT assembly line or a in a dispenser built in a stencil printer there are two main systems to push the solder paste out of the syringe: Air pressure and the Archimes screw. Air pressure systems are usually cheaper but the volumetric stability of the solder paste deposits is a bit more difficult to control, especially when the syringe is almost empty and there is a bigger volume of compressed air in combination of less material in the syringe that needs to be moved by this air pressure. Systems with the Archimedes screw are usually more stable and faster. However depending on the solder paste quality, they can be sensitive to some very fine particles of the solder paste that are squashed between the Archimedes screw and the side walls which can block the needle where the solder paste comes out. The smaller and longer the needle, the higher the risk on needle blocking. The needle size is chosen according to the size of the desired solder deposit. The grain size of the solder paste is chosen according to this needle size. In general a type 3 solder paste can be used for needles with an inner diameter bigger than 0,5mm, a type 4 for needles with an inner diameter down to 0,25mm, a type5 for needles with an inner diameter down to 0,15mm.  The dispensing performance of a solder paste can vary from one type to another in terms of volumetric stability and sensitivity to needle blocking. If a syringe of solder paste has been stored too long, too warm or too cold, this can also affect the dispensing performance. How much time and temperature  will affect the dispensing performance may also vary from one solder paste to another. Solder paste for dispensing can be available in different types of syringes required by the machine where its intended use is for. They can also be available with different types of plungers required by the viscosity of the solder paste to be dispensed. Standard sizes for syringes are 5CC, 10CC and 30CC.

  • Reflow soldering is the most used soldering process in electronics assembly. Mainly SMD (Surface Mount Device) components but also some through hole components are soldered in a reflow oven to a PCB (Printed Circuit Board) by means of a solder paste. The reflow oven is usually a forced convection oven but also vapor phase and IR ovens are possible. The first step of the process is to apply solder paste to the pads of the PCB or in case of through hole components in the through hole. This latter is called Pin in Paste (PiP) or intrusive reflow technology. The main application method is stencil printing but also dispensing and solder paste jetting are possible. Depending on the application method the solder paste will have a different consistency and comes in a different packaging. Solder paste is a mixture of a solder powder and a gel flux. The type of gel flux and the type of powder and in what ratios they are mixed, will determine the consistency of the paste. The solder powder is made of a certain soldering alloy and has a certain grain size (distribution). Finer grains size are used for smaller pitch components and smaller stencil apertures. Dispensing and even more jetting also require finer grain sizes. The gel flux contains substances to deoxydize the surfaces to be soldered. It also contains substances that will determine the consistency and the behavior of the solder paste in the process to a great extent. When stencil printing solder paste, an important parameter is that the solder paste keeps its printing properties during the time it will be on the stencil. This is often referred to as the stability of the solder paste. Solder paste stability is hard to quantify but can be estimated from the stencil life indication in the technical datasheet. After solder paste application SMD components  are placed on the solder paste with their solderable connections. In most cases, this is done with a Pick and Place machine. The solder paste needs to have enough adhesion force to keep the components in their place until soldering. A conveyor will transport the PCB through a reflow oven where the PCB board is submitted to a reflow soldering profile. This profile is created by the temperature settings of the different convection zones. They are usually situated as well from the top as from the bottom side.  Beside the temperature settings, in some cases also the convection rate of the zones can be programmed to get better or lower heat transfer, or when some high components experience too much force from the convection. It is the goal to get all components to soldering temperatures, which is determined by the used soldering alloy, without damaging or overheating temperature sensitive components. This can be a challenge for units with a large diversity of big and small components or an uneven Cu-distribution in the PCB board. In that perspective a low melting point soldering alloy substantially limits the risk of damaging or predamaging components and PCB boards. The speed of the conveyor will determine the time of the profile and the throughput of the oven. In most cases however the Pick and Place process is limiting the throughput.  Not all electronic components are suitable for reflow soldering. Some because of their thermal mass like e.g. big transfos or others because of their thermal sensitivity like e.g. some displays, connectors, relays, fuses,... These components are usually available as a through hole components and soldered in other processes like selective soldering, wave soldering, hand soldering, robot soldering, laser soldering,...

  • Dip soldering is a technology used to solder surfaces by dipping/immersing them in liquid solder. It is mainly used for wires and cables and also for the leads of some electronic and mechanical components. Dip soldering applies a layer of solder on the surface that will provide a good solderability for the following soldering processes. The solderability of this layer is maintained very well during storage. Dip soldering can also be used in rework and repair of a PCB (Printed Circuit Board) to e.g. remove or resolder a through hole connector. The dipping process can be done manually or by an automated process. Before soldering the lead or wire is dipped in a soldering flux. To avoid flux residues after soldering, the dipping depth in the flux is usually lower or just as deep as the dipping depth in the solder. Depending on the solderability of the surfaces to be pre-tinned, different fluxes can be used. For surfaces that are hard to solder, like Ni, Zn, brass, heavily oxidized Cu,...usually water soluble fluxes are being used. They provide excellent solderability but can be and must be cleaned in a water based washing process afterwards, as the residues of these fluxes might create problems (like e.g. corrosion). For surfaces with normal solderability IF 2005C or PacIFic 2009M can be used. The soldering alloy in most cases is Sn(Ag)Cu based. The temperature of the soldering alloy is usually higher than for wave and selective soldering because this speeds up the process and the risk on damaging components is very limited. It is also possible that the dipping process needs to remove/burn off the coating of the Cu-wire to be tinned, this also requires higher temperatures. In general soldering temperatures vary from 300-450°C. These temperatures will oxydise the surface of the solder bath quite strongly. The use of Anti-Oxydant pellets can compensate for this oxydation. Some solder baths mechanically remove the top layer of the solder bath with a scraper just before the component is dipped into the solder. Dipping times very much depend on the thermal mass of the component to be soldered and usually are from 0,5s to 3s.

  • Rework and repair on an electronic unit can be performed on defective electronic units that return from the field but can also be necessary in an electronic production environment to correct defects in the assembly and soldering processes. Typical rework and repair actions involve the removal of solder bridging, adding of solder to poor through hole filled components or adding missing solder, replacing wrong components, replacing components that are placed in the wrong direction, replacing components that have defects related to the high soldering temperatures in the processes, adding components that were left out of the process due to e.g. availability or temperature sensitivity. The identification of these defects can be done by visual inspection, by AOI (Automated Optical Inspection), by ICT (In Circuit Testing, electrical testing) or by CAT (Computer Aided Testing, functional testing). A lot of repair operations can be done with a hand soldering station that has a (de)soldering iron with temperature setting. Solder is added by means of a solder wire that is available in several alloys and diameters and contains a flux inside. In some cases a liquid repair flux and/or a gel flux are used to make the hand soldering process easier. For bigger componnets, like BGAs (Ball Grid Array), LGA's (Land Grid Array) QFNs (Quad Flat No Leads), QFPs (Quad Flat Package), PLCCs( Plastic Leaded Chip Carrier),...a repair unit can be used that simulates a reflow profile. These repair units are available in different sizes and with different options. In most cases they contan a preheating from the bottom side that is usually IR (Infrared). This preheating can be controlled by a thermocouple that is placed on the PCB. Some units have a pick and place unit that facilitates the correct positioning of the component on the PCB. The heating unit is usually hot air or IR or a combination of these two. With the aid of thermocouples on the PCB, the heater is controlled to create the desired soldering profile. In some cases the challenge is to bring the component to soldering temperatures without remelting adjacent components. This can be difficult when the component to be repaired is big and has small components near to it. For BGAs with balls made of a soldering alloy, a gel flux can be used or a liquid flux with higher solid content. In this case the solder for the solder joint is provided by the balls. But also the use of a solder paste is possible. The solder paste can be printed on the leads of the component or on the PCB. This requires a different stencil for each different component. The BGA can also be dipped in a special dipping solder paste that first is printed in a layer with a stencil with one large aperture and a certain thickness. For QFNs, LGAs QFNs, QFPs, PLCCs,...solder needs to be added to make a solder joint. In some cases QFPs can be hand soldered but the technique requires experience so the use of a rework unit is preferred. QFPs and PLCCs have leads and can be used with a dipping solder paste. QFNs, LGA's QFNs who do not have leads but flat contacts cannot be used with a dipping solder paste dipped because their bodies would contact the solder paste. In this case the solder paste needs to be printed on the contacts or on teh PCB. In general it is easier to print solder paste on the component than on the PCB, especially when a so-called 3D stencil is used that has a cavity where the position of the component is fixed. Replacing through hole components can be done with a hand (de)soldering station. This is usually done by placing a hollow desoldering tip over the bottomside of the component lead that can suck away solder from the hole. The desoldering tip will have to heat all the solder in the through hole until it is fully liquid. For thermally heavy boards this can be very difficult. In this case, also the top side of the solder joint can be heated with a soldering iron.  Alternatively the board can be preheated over a preheating before the desoldering operation. Soldering the through hole component is usually done with a solder wire that contains more flux or alternatively extra rework flux is added to the through hole and/or on the component lead. For larger through hole connectors, a dip soldering bath can be used to remove the connector. If accessibilty on the PCB is limited a nozzle with its size adapted to the connector can be used. The use of flux in this operation is recommended.

Key advantages

  • A large process window in time and temperature is usually needed when soldering components and PCBs (Printed Circuit Boards) with heavy thermal mass. These boards and components require a lot of heat to get them to soldering temperatures. This takes time and in some soldering process also requires elevated temperatures. The soldering chemistry will have to withstand/survive these increased times and elevated temperaures.  The biggest challenge is soldering heavy thermal mass through hole components on a heavy thermal mass PCB. On a through hole the required heat for soldering is needed on both sides of the board. This heat is usually applied only from one side and will have to pass through the board to the other side. If the PCB board has many Cu-layers, thick Cu-layers, and layers that are fully connected to the through hole barrel, a lot of heat will be deviated to the side and more heat will have to be applied to the board to get enough heat on the other side. In some processes the heat is applied from both sides of the board in a preheating. This will facilitate trough hole soldering on these thermally heavy electronic units.  However if there are temperature sensitive components present on the side where the preheating is applied, care must be taken not to overheat and (pre)damage those components

  • Low transparent residue

  • Suitable for reballing and BGA rework

  • Ball Grid Arrays (BGAs), J-lead and Gull wing ICs are components that are, because of their physical lay-out) difficult to rework with a normal (de)soldering station. In most cases rework and repair is done with a rework station that can simulate a reflow profile. The use of soldering chemistry that is specifically designed for this process is mandatory to get a good final result. Depending on the component that is being reworked and the process step, different types of soldering chemistry can have the preference. A flux gel is often used because of its large process window. Different viscosities of the flux gel will support different application methods, like dispensing, application by brush, stencil printing, pin transfer, dipping,... Liquid repair fluxes on the other hand allow very precise application with a flux pen with glass fibre tip and will give lower residue formation than gel fluxes. Low residue is sometimes required because of esthetic reasons but also when a conformal coating needs to be applied or for applications that can be sensitive to residues like e.g. high frequency electronics. Low residue will also facilitate the use of an Ersascope that is used to look underneath a BGA after soldering. The process window of liquid fluxes however is smaller than that of gel fluxes. Solder pastes can also be used for rework and repair of Ball Grid Arrays (BGAs) but certainly for J-lead and Gull wing ICs that need the extra solder for the solder joint. For stencil printing the same solder paste as for the SMT process can be used. For dipping, which can be used for components that have a stand-off between the body of the component and solderable leads, a special dipping solder paste is used which will give a repeatable quantity of solder on the leads that are dipped into the dipping paste. 

  • The ERSA Dip&Print Station is part of a rework station for electronic components that are hard to repair with a standard (de)soldering station. For example Bottom Terminated Components (BTCs), like Ball Grid Arrays (BGAs), QFNs, DFNs, LGAs,...but also some J-lead and Gull wing ICs like QFPs and PLCCs are components that need a special rework station. The ERSA Dip&Print Station is designed to apply solder paste or flux gel to those components by means of stencil printing or dipping. The use of soldering chemistry that is specifically designed for this process is mandatory to get a good final result. For dipping, which can be used for components that have a stand-off between the body of the component and solderable leads, a special dipping solder paste is used which will give a repeatable quantity of solder on the leads that are dipped into the dipping paste. For stencil printing the same solder paste as for the SMT process can be used. A flux gel can be used for both stencil printing and dipping. A flux gel can only be used when enough solder is present to make a solder joint as is the case for e.g. BGAs.

  • Colophony, also called rosin, is a substance derived from trees that is typically used in soldering fluxes. It can be used in liquid fluxes as well as in gel fluxes. Colophony containing fluxes can be identified by the denomination 'RO' in the IPC classification. Colophony in general provides a good process window in time and temperature but has a number of disadvantages depending on the application that the colophony containing flux is used in. In liquid fluxes for wave and selective soldering, the colophony will give an increased risk on blocking the nozzle of spray and micro jet flux application systems, resulting in more maintenance and higher risk on bad soldering results. The residues of a rosin (=colophony) based flux in the soldering machine and on tools and carriers are quite hard to remove and a solvent based cleaner is usually needed. When the flux with colophony accidentally ends up on the contacts of a connector or contact comb structures like for a remote control or in electro mechanical contactors / relays / switches, it is known to give contact problems and malfunctioning of the electronic unit in the field.  Furthermore the residues of the flux that remain on the board can give contact problems with electrical pin testing ( ICT= In Circuit Testing) which can result in delays in production because of false errors. This usually requires cleaning of the PCB and/or the test pins. These expensive test pins are rather fragile and sensitive to be damaged by cleaning.  Furthermore the residues of a rosin flux are known not to be compatible with conformal coatings in time. The rosin residue forms a separation layer between the PCB and conformal coating that in time can cause detaching of the conformal coating and also cracking, especially when the electonic unit experiences a lot of temperature cycles (warming up and cooling down).  For those reasons fluxes without colophony and more specifically fluxes from the 'OR' classification are generally used for wave and selective soldering. Colophony can also be used in solder wires. Although the colophony provides a good process window in time and temperature, it is very sensitive to discoloration when heated. The discoloration will depend on the type of colophony and the temperature it has seen. As soldering tip temperatures are usually quite high, the colophony in the solder wire will give quite heavy visual residue formation around the solder joints. This will distinguish them from the other solder joints made in reflow, wave and selective soldering. When this is not desirable a cleaning operation needs to be performed. Furthermore the fumes of a colophony containing solder wire are considered hazardous. A fume extraction is mandatory but anyway advisable for any hand soldering operation. Colophony containg wires are still being used quite a lot but colophony free solder wires and more specifically solder wires from the 'RE' classification are gaining importance. Colophony is also used in solder pastes. Beside giving a good process window in time and temperature, it also provides a good stability of the solder paste on the stencil. This will facilitate a stable printing process and hence stable soldering results and defect rates. The discoloration of the rosin in reflow soldering is not so prominent as it is with a solder wire because the temperatures in reflow soldering are lower than in hand soldering. Still the rosin residue has poor compatibility with conformal coating and in time after thermal cycles it might show cracks or detatching of the conformal coating. Although most manufacturers will apply the conformal coating over the solder paste residues, for optimal results it is advisable to clean off the solder paste residues. Giving the benefits of colophony described above, most solder pastes contain colophony.

  • Absolutely halogen free soldering chemistry contains no intentionally added halogens nor halides. The IPC classification allows up to 500ppm of halogens for the lowest 'L0' classification. Soldering fluxes, solder pastes and solder wires from this class are often referred to as 'halogen free'. Absolutely halogen free soldering chemistry goes one step further and does not contain this 'allowed' level of halogens. Specifically in combination with lead-free soldering alloys and on sensitive electronic applications, these low levels of halogens have been reported to cause reliability problems like e.g. too high leakage currents.  Halogens are elements from the periodic table like Cl, Br, F and I. They have the physical property that they like to react. This is very interesting from the point of view of soldering chemistry because it is intended to clean off oxides from the surfaces to be soldered. And indeed halogens perform that job very well, even hard to clean surfaces like brass, Zn, Ni,...or heavily oxidized surfaces or degraded I-Sn and OSP (Organic Surface Protection) can be soldered with the aid of halogenated fluxes. Halogens provide a great process window in solderability. The problem however is that the residues and reaction products of halogenated fluxes can be problematic for electronic circuits. They usually have high hygroscopicity and high water solubility and give an increased risk on electro migration and high leakage currents. This means a high risk on malfunctioning of the electronic circuit. Specifically with lead-free soldering alloys there are more reports that even the smallest levels of halogens can be problematic for sensitive electronic applications. Sensitive electronic applications are typically high resistance circuits, measuring circuits, high frequency circuits, sensors,...That's why the tendency is to move away from halogens in soldering chemistry in electronics manufacturing. In general when the solderability of the surfaces to be soldered from component and PCB (Printed Circuit Board) are normal, there is no need for these halogens. Smartly designed absolutely halogen free soldering products will provide a large enough process window to clean the surfaces and get a good soldering result and this in combination with high reliability residues. 

  • When a soldering product is labelled No-clean, this means that  soldering product has passed reliability testing like a Surface Insulation Resistance(SIR) test or an electro(chemical) migration test. These tests are designed to test the hygroscopic properties of the residues of the soldering product under elevated temperature and high relative moisture conditions. No-clean is an indication that the residues can remain on the electronic unit after the soldering process without being cleaned. This will apply for by far most of the electronic applications. For very sensitive electronic applications, which are typically high resistance electronic circuits, high frequency electronic circuits, etc... it is possible that cleaning of the electronic unit is necessary. It is always the responsibility of the electronic manufacturer to judge wether cleaning is necessary or not.

  • RoHS stands for Restriction of Hazard Substances. It is a European directive: Directive 2002/95/EC. It restricts the use of some substances that are considered Substances of Very High Concern (SHVC) in electrical and electronic equipment for the territory of the European Union. A listing of these substances can be found below: Please note that this info is subject to change. Always check the website of the European Union for most recent information: https://ec.europa.eu/environment/topics/waste-and-recycling/rohs-directive_nl https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011L0065 1. Cadmium and cadmium compounds  2. Lead and lead compounds  3. Mercury and mercury compounds(Hg)  4. Hexavalent chromium compounds(Cr)  5. Polychlorinated biphenyls (PCB)  6. Polychlorinated naphthalenes (PCN)  7. Chlorinated paraffins (CP)  8. Other chlorinated organic compounds  9. Polybrominated biphenyls (PBB)  10. Polybrominated diphenylethers (PBDE) 11. Other brominated organic compounds  12. Organic tin compounds (Tributyl tin compounds, Triphenyl tin compounds)  13. Asbestos  14. Azo compounds  15. Formaldehyde  16. Polyvinyl chloride (PVC) and PVC blends  17. Decabrominated diphenyl ester (from 1/7/08)  18. PFOS : EU directive 76/769/EEC (not allowed in a concentration equal to or higher than 0.0005% by mass) 19. Bis(2-ethylhexyl) phthalate (DEHP)  20. Butyl benzyl phthalate (BBP)  21. Dibutyl phthalate (DBP)  22. Diisobutyl phthalate 23. Deca brominated diphenyl ester (in electrical and electronic equipment) Other countries outside of the European Union have introduced their own RoHS legislation, which is to a great extent very similar to the European RoHS. 

Physical & chemical properties

RE L0 to EN and IPC standards
Halide content
Available viscosities
210 kcps, 70 kcps, 25 kcps