Cold Plate and Heat Sink Soldering

Bonding Solutions

S-Bond active solder alloys are excellent bonding materials for a wide range of materials used in heat sink soldering for electronics, medical imaging devices and industrial equipment. These are traditionally assembled using flux and conventional solders, while also preplating the aluminum with nickel. Plating can be costly and difficult to schedule with the reduced number of platers and the cost of handling plating wastes. Also, when bonding large flat areas using fluxes, the entrapment of flux and flux residue in the large ( over 1” x 1”) interface areas lead to a reduced bond area and residual flux leach out. An aluminum finned to copper heat sink is shown to the left.

S-Bond joining of heat sinks lowers the number of steps required for joining. S-Bond® materials join well to copper, aluminum and even composite materials of the same base such as Al:SiC and Cu-G. Frequently, S-Bond offers a lower total end-cost product compared to a conventional joining process since plating and flux clean-up are not required. Depending on the application, this can offer a lower cost-in-use and reduced waste generation compared to conventional processes by eliminating plating baths, flux application, flux fume removal and flux cleaning.

A typical water cooled cold plate may have copper tubes bonded into an aluminum structure as seen to the left. Actively cooled cold plates utilize copper or aluminum tubes. They are typically bonded into aluminum plates to reduce weight and optimize thermal conductivity thus minimizing hot spots on the electronics that may be mounted onto the plates. Alternatively, cold plates may have machined passages that need to be covered and sealed to contain the cooling fluid. S-Bond joining is an effective means to join Al-Al, Cu-Cu and Al-Cu cold plates in any combination of materials or design.

S-Bond joining is fluxless, therefore the incompatibly of copper and aluminum fluxes is not a problem and the entrapment of flux in channels does not occur. This eliminates the need for post-joining cleaning and the potential corrosion from residually entrapped flux.

Contact Us to see how S-Bond can make your cold plate and heat sink soldering more efficient.  Also see our Technical Resources section to find related white papers and technical bulletins.

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