Aluminum soldering is used in making small area electrical and/or thermal connections or seals to other metal or ceramics, while aluminum bonding is used to join large areas either for thermal and/or structural purposes. Aluminum soldering finds applications in sensors, electronics, and electrical power where aluminum contact and/or wire leads are being utilized. Aluminum soldering has also been used as a means to seal and/or repair aluminum heat exchangers.
We have been contacted many times for assistance in solving the problem of small contact to aluminum without the use of aggressive chemical flux or cases where the chemical flux for aluminum was not compatible with the metals of the opposing side of the joint. Additionally, in many electronic packages the use of corrosive aluminum soldering fluxed are limiting When faced with these choices, active fluxless solders such as S-Bond become a good solution. Read more about Applications For Aluminum Soldering →
Bond assembly can be done via 1) mechanical attachment, 2) adhesive bonding of which epoxy bonding is one form of adhesive, 3) soldering bonding using lower melting filler metals (< 450˚C), 4) brazing using filler metals melting above 450˚C, and 5) welding such as resistance welding bonding, ultrasonic welding and friction weld bonding that uses locally melted parent metal.
Bonding is done for a variety of technical reasons a) mechanical attachment, b) thermal contact, c) electrical contact d) gas or liquid seal, or e) any or all combinations thereof. The choice of bonding method will then depend on the intrinsic properties of the bonding filler materials ( i.e. hermetic, electrical conductance, thermal conductance, thermal coefficient of expansion, adhesive bond strength related to the intrinsic fillers’ mechanical properties, and their adhesive and cohesive strengths). Read more about Epoxy Bond vs. Solder Bond Applications →
Metal to metal bonding is used in many applications for fabricating components where the metallic parts are too large or too complex to make from one piece of metal or the assembly contains dissimilar metals for various functions, such as: 1) physical properties such as electrical or thermal conductivity, 2) differences in thermal coefficient of expansion, 3) differences in corrosion, 4) differences in strength and/or modulus. For designers to utilize the optimum combination of metal properties, it is useful to have metal to metal bonding properties that optimally combine metals in an assembly.
Bonding technologies include: 1)Mechanical fastening, 2) Epoxy bond, 3) other Metal Adhesives, 4) Diffusion Bonding, 5) Explosive Bonding, 6) Weld & Weld Cladding, 7) Ultrasonic Welding, 8) Brazing and Soldering and 9) specialized active solder bonding. For strength mechanical fastening and welding are favored… for low cost, epoxy and other adhesive metal bonding are best but have limitations with regard to sealing, thermal conductivity, and stability over time. Diffusion and explosive bonding perhaps provides the best strength and interfaces between metals. However; for the best combination of bond properties and the least effect on base metal properties; ultrasonic welding, brazing, or soldering are the processes of choice. The choice of bonding process also entails the area of bond required, the joints’ physical properties and the effect the bonding process has on the base metal properties… all these are considerations when selecting bonding process. Read more about Metal to Metal Bonding →
Think of the smartphone you hold in your hand, or of your tablet or laptop. The amount of processing power they contain dwarfs offerings from just a few years ago. Theoretically, the parts should be much hotter from doing so many more operations. They are not and one of the biggest reasons why is aluminum soldering and aluminum bonding applications.
Basics of Thermal Management in Manufacturing
Many of the advancements for electronics manufacturing, and other industries that benefit from aluminum soldering, revolve around miniaturization. Parts are smaller, which in some cases mean they are more fragile. In the case of solid-state lighting and LEDs, the advancement in efficiency comes at a price as well: the area of the product where the light is created can hit high temperatures of up to 150 degrees Celsius at the absolute maximum, according to Cree LED data sheets. Read more about Aluminum Bonding and Heat Management in Manufacturing →
Active solder, S-Bond® alloys have been developed to bond to a range of metals, ceramics and composite materials without the need for fluxes of preplating. In particular, such active solder alloys have an affinity for joining aluminum to itself and other metals and ceramics. Aluminum soldering has gotten simpler with the emergence of such S-Bond® solders. Just melt the S-Bond filler metals, mechanically spread them on the surface via brushing, rubbing, or via ultrasonically activated spreaders and the alloys will wet, adhere and provide a base for bonding. In a subsequent step, when two molten pre-tinned S-Bond layers are pressed or slid together the S-Bond layers will activate a strong solder bond. Read more about Aluminum Bonding with Active Solders →
Mechanical vs Chemical Fluxing During Solder Bonding
Flux is derived from Latin word fluxus meaning “flow.” In solder joining (also aluminum soldering, graphite bonding, ceramic to metal brazing, etc.), a flux facilitates wetting by molten metals disrupting oxides on metal surfaces which interrupt the reaction/interaction of the molten solder metals with the underlying metal. Additionally, flux allows solder to flow easily on the working piece rather than forming beads as it would otherwise. Read more about Mechanical Activation of Active Solders →
The Issue of Coefficient of Thermal Expansion (CTE) Mismatch
Yes, S-Bond can join a wide variety of materials, including aluminum, copper, stainless steel, refractory metals and ceramic to metal brazing with aluminum oxide, aluminum nitride, silicon carbide and other oxide, nitrides and carbides… however, with this wide variety of materials joining capability, we have a lot of inquiries about aluminum soldering to stainless steel or aluminum oxide, graphite bonding to aluminum, titanium to silicon carbide, etc. Read more about Joining Dissimilar Materials →