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WHICH FLUX/BINDER SYSTEM IS RIGHT FOR ME?
| Brazing Paste Flux/Binders | ||
| Industry Class | Flux System | Description |
|---|---|---|
| Chemistry and properties similar to AWS FB3-A, AMS 3410, and EN 1045 FH10 | STL | Very active, free-flowing flux, for use on both ferrous and non-ferrous base metals. Strong oxide removal capability enables use on many “hard- to-braze materials” like cadmium-oxide and nickel-chrome. Unique blend of flux constituents enable wide temperature activation window and long flux life. |
| BHL | Lower flux content with oxide removal similar to STL. Binder has good adhesion to part, improved slump properties, and increased restrictiveness. Formulation permits higher alloy loading which makes it ideal for a wide range of applications ranging from tube to fitting, to electrical contact applications where alloy coverage and large fllets are preferred. | |
| LHK | Fluxing properties similar to STL. LHK is formulated to have a more restrictive flow than STL in molten state, while maintaining excellent joint penetration and capillary pull through. Ideal for pairing with a wide variety of BAg and BCuP alloys. | |
| Chemistry and properties similar to AWS FB3-C, AMS 3411, and EN 1045 FH20 | STN | Very active, free-flowing flux, provides excellent wetting and alloy spread similar in nature to its FB3-A sister, STL. The STN binder formulation is optimized for higher process temperatures and longer heat cycles typically required for “hard- to-braze materials” as well as many carbide applications. |
| STK | STK is a more restrictive silver brazing flux for use in prolonged heating cycles and when maximum activity at higher process temperatures are required. It is an excellent choice for stainless steels and carbides and is often chosen for use with suitable silver fller metals when brazing and heat-treating operations are combined. | |
| WSK | WSK is specially formulated for long term stability when packaged in cartridges and can handle higher loading levels of most alloys without impacting paste stability. WSK has minimal hot and cold slump characteristics with good capillary flow. The restrictive nature of the binder, along with possible higher alloy loading levels, help minimize post braze footprint which makes it a good selection for plating parts after brazing. | |
| Chemistry and properties similar to AWS FB3-D, AMS 3417, and EN 1045 FH21 | BMW | Very high temperature borate flux with good capillary fow and wetting characteristics. BMW has good adhesive properties to minimize cold and hot slump. Often paired with brass filler metals for use on steel, brass, and copper base metals when the joint requires a smooth filler and good capillary flow (e.g. fishhooks and musical instruments). It can be used with some of the lower temperature nickel filler metals provided optimum process conditions (i.e. fast heat cycle like induction). |
| BMO |
More restrictive version of BMW with good adhesive properties and minimal cold and hot slump. BMO is often used with brass and bronze filler metals for carbide and steel applications (i.e. circular saw teeth) however, it can work with some higher temperature, longer melting range silver alloys. |
|
| BMA | Most restrictive system, with excellent part adhesion, makes BMA a good choice for vertical joints where gravity assist is not favourable. The post braze residue is tougher and more resistant to thermal shock than the BMW or BMO systems. | |
| JAN | Similar to BMW in activation temperatures and physical properties, JAN is a higher fluxed system which enables even longer activation life. Ideal for more prolonged heating cycles when paired with more sluggish alloys. | |
| Brazing Paste Fluxless Binders | ||
| Binder System | Description | |
|---|---|---|
| CAP | CAP and CKG stay in place through heating cycle and are considered quick drying. CAP pastes tend to be less viscous and have higher dispensing flow rates than its thicker sister, CKG. CKG is extremely quick drying, often making it more ideal for vacuum applications. Both stay in place once applied. | |
| CNG | CNG and CNT have similarities to CAP and CKG above. They are quick drying and tend to stay in place through heating cycle. CNG pastes tend to be less viscous and have higher dispensing flow rates, whereas CNT is typically faster drying and often used more commonly in vacuum applications. | |
| BAZ |
This binder family has a wide range of viscosities and dispensing properties. CCR tends to have the most flow and is easily dispensed through squeeze bottles. GAL has the least flow, most body, and is most viscous. Unlike typical aqueous systems, EXO is specifcally formulated for improved performance in Exothermic and Endothermic applications. It has little to no residue under those conditions, however, it is not recommended in High Hydrogen or Vacuum applications. This fast drying product is easily dispensed through both squeeze bottles and air applicators. |
|
| CBC |
Non-drying, neutral binder systems with great versatility. Very sticky and adhesive in nature, these materials are ideal for vertical joints requiring minimal flow and slump properties. They have versatility in a variety of atmospheric environments, and are less reliant on dew points than some other binders. Adhesive nature often results in an oily off-gas, so they are more heating profile dependent to minimize residue build-up on equipment. Formulated to have excellent chain scission during decomposition, PNP and PLA have extremely low residue in a variety of lower temperature furnace applications. They have the ability for high alloy loading and are an excellent choice for vacuum applications, however, their unique formulation leads to pronounced slump, so their use is not recommended for vertical or complex joint designs. |
|
| CP CFW |
CP and CFW are optimized for lower temperature silver and phos-copper alloys. Like PNP and PLA, they have a good residue profles in lower temperature furnace applications. CP can offer extremely high alloy loadings (i.e. 87-90%), however, it does have more pronounced slump, similar to PNP and PLA. Not recommended for vertical or complex joint designs. CFW is formulated to provide improved adhesion over CP. This limits CFW’s loading closer to 80% alloy. Not as adhesive in nature as the CBL or CBC family of products. | |
| CDW | CDW is a hybrid system with excellent versatility in all environmental atmospheres ranging from vacuum furnace to higher dew point exothermic atmospheres. Semi-drying on the part with excellent part adhesion similar to the CBL/CBC family with improved hot and cold slump throughout the staging and brazing cycle times. Has superior snap off / break similar to an aqueous system (i.e. less stringy than CBL/CBC family). | |
| CTT | CTT is formulated to have minimal residue in all environmental atmospheres, ranging from vacuum furnace to higher dew point exothermic atmospheres. CTT is non-drying and an excellent choice for roll coat or stencil applications. Excellent part adhesion with little to no hot and cold slump throughout the staging and brazing cycle times. Unique chemistry typically permits higher alloy loading. Pastes have superior snap off / break similar to an aqueous system (i.e. less stringy than CBL/CBC family). | |
| Aluminum Flux/Binders | |||
| Flux System | Description | AWS A 5.31M | AMS |
|---|---|---|---|
| GNC | Low activation temperature aluminium flux for use with Zinc Aluminium solder fller metals (Fusion 720, 845, and 892). Popular for use in torch or furnace rework applications. Also recommended for small, thin walled aluminium assemblies, heat exchangers, and condenser “piccolo” joints when low temperature, fast activating soldering is required. It produces a hard, white residue which is non-corrosive under most service environments. | — | — |
| Fast activation, general purpose aluminium brazing flux, suitable for a wide range of brazing filler metals. Due to the lower activation temperatures, KNC is often paired with lower temperature aluminium brazing filler metals such as 1022 and 1040. It removes tenacious aluminium oxides, making it ideal for a variety of aluminium base metals including 6061, 6262, 6063, and 3003. Can be used in both torch and furnace applications. | FB1-B3 | — | |
| Strong general purpose aluminium brazing flux with a wide temperature activation range. GNC has potent flux removal power, making it ideal for a wide range of aluminium base metals, including some 5000 series and other magnesium-containing alloys1. Activates at slightly higher temperatures than KNC which makes it ideal for both furnace and torch applications using Fusion’s 1070 and 1080 alloys. | FB1-B3 | — | |
| NDA is a lower activating temperature general purpose flux with a wide activity range. Often paired with the lower temperature aluminium brazing alloys (Fusion 1022 and 1040) however, it can be used with the 1070 alloy provided the process is optimized. Typically used for torch brazing and produces a water washable residue, which much be removed. | FB1-A2 | 34124 | |
| NPA | Strong general purpose aluminium brazing flux with a wide temperature activation range. NPA has potent flux removal power, ideal for most aluminium base metals including some 5000 series and other magnesium-containing alloys1. Activates at slightly higher temperatures than NDA which makes it ideal for pairing with Fusion 1070 and 1080 alloys. NPA is typically used in torch brazing and produces a water washable residue which much be removed. | FB1-A2 | 34124 |
Brazing Aluminium with the Fusion Process
Aluminium is a popular base metal because it is light weight, strong, and relatively chemically inert. For these reasons, Aluminium is used in everything from automobiles to airplanes and each year millions of aluminium parts are joined by brazing and soldering. Common filler metals for aluminium metal joining are primarily based on aluminium and often close to the base metal melting temperatures, so control of heat is a critical process parameter. The table on page 25 outlines popular Fusion aluminium filler metals.
Aluminium joining processes include traditional methods, from flame heating to furnace application. All aluminium joining methods (except vacuum furnace) utilize a flux to remove the tenacious aluminium oxides on the base metals. Fusion has developed a series of proprietary fluxed binder systems which efficiently remove the oxide layers of most aluminium base metals and facilitate a strong joint interface. There are two primary fluxed systems for joining aluminium. First is a non-corrosive system which contains a chloride-free flux. This system leaves an inert post braze residue which does not have any detrimental effect under normal service conditions and does not require removal. The second family is known as a water washable system. Fusion’s water washable system results in a highly soluble post braze residue, however, this residue must be removed after brazing. In general, 90% or more of the residue is often removed by immersing the hot part in water. For a more thorough cleaning, Fusion recommends immersing the finished part in a 15% nitric acid/85% water solution under agitation for 30 seconds at room temperature followed by (2) hot water rinses and a final cold water rinse. The table below describes Fusion’s aluminium flux/binder systems in more detail.
Solder Paste Flux
Solder paste flux is a vital component in the soldering process that facilitates the formation of reliable joints. It serves multiple purposes, including removing oxides from metal surfaces and enhancing the wetting and bonding between the solder and the base metal. Various types of flux can be formulated, each offering unique characteristics and suitability for specific applications.
These binders are specifically formulated to ensure optimum characteristics regardless of the application method or brazing process. Our binder systems fall into two main groups: ‘fluxless’ and ‘fluxed’ binder carrier systems.
Non-Corrosive Fluxes
Non-corrosive fluxes are considered safe for joint integrity when their post-solder residue remains under normal conditions. Typically, these fluxes are rosin-based and may contain mild organic acids or special additives to enhance fluxing action and oxide removal. The active constituents of these fluxes decompose at soldering temperatures, leaving behind an inert residue that does not require removal. Non-corrosive fluxes are particularly suitable for electrical applications, as their non-conductive and non-corrosive residue can be left on assemblies without causing harm. Common non-corrosive solder flux systems include:
GPR: General-purpose electronics flux with average restrictive action, leaving behind a hard, slightly opaque, sticky, and non-conductive residue.
MBC: Activated rosin system with good capillary flow, resulting in a softer, slightly sticky, non-conductive residue.
LPS: A highly restrictive, activated rosin system binder ideal for applications requiring localised alloy deposits, producing a slightly sticky, non-conductive residue.
Intermediate Fluxes
Intermediate fluxes typically consist of mild organic salts with stronger activation properties compared to non-corrosive additives. These fluxes activate at soldering temperatures and have a relatively short activity period. While the residues left after soldering are not harmful to the joint, they should be removed whenever possible to prevent potential corrosion triggered by moisture in the atmosphere. Common intermediate solder flux systems include:
PA, PAN, PAD Family: Low activation temperature fluxes often paired with fusible alloys. PA is the most restrictive system with good slump characteristics, while PAN and PAD offer easier residue removal.
WC: A mild organic halide flux with good oxide removal power, leaving a mildly water-soluble residue.
PMS & PWC Family: Mild organic halide fluxes with excellent fluxing action, ideal for copper and brass applications. Residues in this family are oilier and require hot water or detergent for removal
SUN: An extremely mild organic acid flux that behaves like a non-corrosive system with higher alloy loading capability.
Corrosive Fluxes
Corrosive fluxes are derived from inorganic acids and salts. They possess high activity and long flux life even at elevated temperatures, making them effective for removing stubborn oxides, particularly on stainless steel base metals. Residues from these fluxes form inorganic, metallic-oxide salt complexes that remain chemically active and must be removed to prevent corrosion and maintain joint integrity. Common corrosive flux systems include:
SFC, FCC, 2JN, SMH Family: Strong, inorganic fluxes with varying levels of restrictive action. They are suitable for oven applications and longer heat cycle processes.
PPP, SSX, SSE Family: Extremely strong inorganic fluxes ideal for combating tenacious oxides. They have moderate restrictive action and excellent capillary flow but require optimized processes to prevent jumping or popping.
WCC, WCE, WCS Family: Very active inorganic halide flux systems suitable for steel, stainless steel, and plated surfaces. These fluxes offer good capillary flow and varying levels of restrictive action, often used in fast heating cycles.
By understanding the different types of solder paste flux and their specific characteristics, you can make informed choices for your soldering applications. Selecting the appropriate flux ensures optimal oxide removal, wetting properties, and joint integrity, ultimately leading to reliable and high-quality soldered connections.
Choose the solder or brazing paste flux that best suits your requirements and consult with our experts to optimise your process.